# December 2010, Volume 19, Number 4

**R. Marsalek, M. Nekovee**
[full-text]

Guest Editorial: Cognitive Radio Communications and Software Defined Radio

**G. Baudoin, M. Villegas, M. Suarez, A. Diet, F. Robert**
[references] [full-text]

Performance Analysis of Multiradio Transmitter with Polar or Cartesian Architectures Associated with High Efficiency Switched-Mode Power Amplifiers (invited paper)

This paper deals with wireless multi-radio transmitter architectures operating in the frequency band of 800 MHz – 6 GHz. As a consequence of the constant evolution in the communication systems, mobile transmitters must be able to operate at different frequency bands and modes according to existing standards specifications. The concept of a unique multiradio architecture is an evolution of the multistandard transceiver characterized by a parallelization of circuits for each standard. Multi-radio concept optimizes surface and power consumption.

Transmitter architectures using sampling techniques and baseband ΣΔ or PWM coding of signals before their amplification appear as good candidates for multiradio transmitters for several reasons. They allow using high efficiency power amplifiers such as switched-mode PAs. They are highly flexible and easy to integrate because of their digital nature. But when the transmitter efficiency is considered, many elements have to be taken into account: signal coding efficiency, PA efficiency, RF filter. This paper investigates the interest of these architectures for a multiradio transmitter able to support existing wireless communications standards between 800 MHz and 6 GHz. It evaluates and compares the different possible architectures for WiMAX and LTE standards in terms of signal quality and transmitter power efficiency.

- KAHN, L. R. Single sideband transmission by envelope elimination and restoration. Proc. IRE, July 1952, vol. 40, no. 7, p. 803-806.
- RAAB, F., et al. RF and microwave power amplifier and transmitter technologies. High Frequency Electronics, May- November 2003, p 22-49.
- STAUDINGER, J. et al. High efficiency CDMA RF power amplifier using dynamic envelope tracking technique. In Int. Microwave Symp. Digest. Boston (MA), June 13-15, 2000, vol. 2, p. 873-876.
- LIE, D.Y.C., YAN LI, LOPEZ, J., STANLEY WU, TZU-YIN YANG Design of highly-efficient wideband RF polar transmitters using Envelope-Tracking (ET) for mobile WiMAX/Wibro applications. In Proc. 8th International Conference on ASIC, 2009. ASICON '09. IEEE, Changsha, Hunan, Oct. 2009, p. 347-350.
- COX, D. Linear amplification with nonlinear components. IEEE Transactions on Communications, Dec 1974, vol. 22, no. 12, p. 1942 – 1945.
- COX, D. A high-efficiency RF transmitter using VCO-derived synthesis: CALLUM. In Proc. of IEEE Radio and Wireless Conference, RAWCON. USA, 1998, p. 137-140.
- COX, D. Linear amplification by sampling techniques: A new application for delta coders. IEEE Transactions on Communications, Aug 1975, vol. 23, no. 8, p. 793 – 798.
- DIET, A., VILLEGAS, M., BAUDOIN, G. EER-LINC RF transmitter architecture for high PAPR signals using switched power amplifiers. Physical Communication, ELSEVIER, Dec. 2008, p. 248-254.
- WAGH, P., MIDYA, P. High-efficiency switched mode RF power amplifier. In 42nd Midwest Symposium on Circuits and Systems, 1999, p. 1044-1047.
- JAYARAMAN, A., CHEN, P. F., HANINGTON, G. et al. Linear high-efficiency microwave power amplifiers using bandpass delta- sigma modulators. IEEE Microwave and Guided Wave Letters, 1998, vol. 8, no. 3, p. 121-123.
- BERLAND, C., HIBON, I., BERCHER, J.-F., VILLEGAS, M., BELOT, D., PACHE, D., LE GOASCOZ, V. A transmitter architecture for Nonconstant Envelope Modulation. IEEE Trans. Circuits and Systems II: Express Briefs, 2006, vol. 53, no. 1, p. 13- 17.
- JEONG, J., WANG, Y. E. A Polar Delta-Sigma Modulation (PSDM) scheme for high efficiency wireless transmitters. In IEEE MTT-S Int. Microwave Symp. Dig. June 2007.
- BAUDOIN, G., BERLAND, C., VILLEGAS, M., DIET, A. Influence of time and processing mismatches between phase and envelope signals in linearization systems using Envelope Elimination and Restoration, application to hiperlan 2. In Proc. Conf. IEEE - MTT'2003 Microwave Theory and Technique. Philadelphia (USA), June 2003.
- GUTIERREZ, J., ARIAUDO, M., PACHE, D. GAUTIER, J.-L., BERLAND, C. BiCMOS Implementation of a full-digital linearized system for complex modulation transmitter. In Proc. of EuMW 2010, Paris.
- SUAREZ PENALOZA, M. L., BAUDOIN, G., VILLEGAS, M. A Cartesian Sigma-Delta transmitter architecture. In Proc. of IEEE Radio and Wireless Symposium. USA, Jan. 2009.
- Air Interface for Fixed and Mobile Broadband Wireless Access Systems Amendment 2: Physical and Medium Access Control Layers for Combined Fixed and Mobile Operation in Licensed. IEEE Std. 802.16e, 2005.
- 3GPP TS 36.101 V8.3.0 (2008-09). Technical Specification 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); User Equipment (UE) radio transmission and reception (Release 8), 2009.
- SUAREZ PENALOZA, M. L., VILLEGAS, M., BAUDOIN, G. Front-end filtering requirements on a mobile cognitive multi-radio transmitter. In Proc. 2008 International Symposium on Wireless Personal Multimedia Communications, Finland.
- SCHREIER, R., TEMES, G. C. Understanding Delta-Sigma Data Converters. Wiley-IEEE Press, 2004.
- NIELSEN, M., LARSEN, T. Transmitter architecture based on ΔΣ modulation and switched power amplification. IEEE Trans. on Circuits and Syst. II, 2007, vol. 54, no. 8, p. 735-739.
- ROBERT, F., SUAREZ PENALOZA, M. L., DIET, A., VILLEGAS, M., BAUDOIN, G. Study of a polar sigma-delta transmitter associated to a high efficiency switched mode amplifier for mobile WiMAX. In 10th annual IEEE Wireless and Microwave Technology Conference, WAMICON, 2009, USA.

Keywords: Multiradio transmitter, high-efficiency RF transmitter, polar transmitter architectures, Cartesian transmitter architectures, class E power amplifier, Sigma-Delta coding, PWM coding, WiMaX, LTE

**Y. Cui, Z. Zhao, H. Zhang**
[references] [full-text]

An Efficient Filter Banks Based Multicarrier System in Cognitive Radio Networks (invited paper)

In cognitive radio techniques, OFDM is usually regarded as the physical layer candidate. However, the weaknesses of the OFDM technique, i.e., using plain FFT for spectral analysis , decreased bandwidth efficiency due to CP (cyclic prefix), high out-of-band emission, have been pointed out and the introduction of filter banks based multicarrier (FBMC) system has been advocated by a number of authors. In this paper, we propose an efficient FBMC system for cognitive radio network. At the transmitter, we propose a decimation transform decomposition method to eliminate the unnecessary zero operations. At the receiver, we utilize the analysis filter banks to sense the spectrum bands. In order to conquer the shortages of the traditional filter banks, we propose a multistage analysis filter banks, which can reduce the computational complexity while improve the detection precision when used to sense the spectrum bands. And with an adaptive threshold scheme in the power estimator, the threshold can be kept very close to the noise power, which can increase the detection probability especially in the condition of low SNR.

- MITOLA, J., MAGUIRE, G. Q. Cognitive radios: making software radios more personal. IEEE Personal Communications, Aug. 1999, vol. 6, no. 4, p. 13-18.
- HAYKIN, S. Cognitive radio: brain-empowered wireless communications. IEEE Journal of Selected Areas in Communications, Feb. 2005, vol. 23, no. 2, p.201-220.
- ZHANG, Q., KOKKELER, A. B. J, SMIT, G. J.M. An oversampled filter bank multicarrier system for Cognitive Radio. In IEEE Personal, Indoor and Mobile Radio Communications (PIMRC). Cannes (France), 2008, p. 1-5.
- WALDHAUSER, D. S., BALTAR, L. G., NOSSEK, J. A. Comparison of filter bank based multicarrier systems with OFDM. In IEEE Asia Pacific Conference on Circuits and Systems (APCCAS). Singapore, 2006, p. 976-979.
- BEHROUZ, F. B. Filter bank spectrum sensing for cognitive radios. IEEE Transactions on Signal Processing, May 2008, vol. 56, p. 1801-1811.
- SHEIKH. F., BING, B. Cognitive spectrum sensing and detection using polyphase DFT filter banks. In Proceedings of IEEE Consumer Communications and Networking Conference (CCNC 08). Las Vegas (USA), Jan. 2008, p. 973-977.
- MARKEL, J. FFT pruning. IEEE Transactions on Audio and Electroacoustics, 1971, vol. 19, p. 305-311.
- SKINNER, D. Pruning the decimation in time FFT algorithm. IEEE Transactions on Acoustics, Speech and Signal Processing, 1976, vol. 24, p. 193-194.
- ALVES, R. G., OSORIO, P. L., SWAMY, M. N. S. General FFT pruning algorithm. In Proceedings of the 43rd IEEE Midwest Symposium on Circuits and Systems. Lansing (MI, USA), 2000, vol. 3, p. 1192-1195.
- SORENSEN, H. V., BURRUS, C. S. Efficient computation of the DFT with only a subset of input or output points. IEEE Transactions on Signal Processing, 1993, vol. 41, p. 1184-1200.
- COOLEY, J. W., TUKEY, J. W. An algorithm for machine computation of complex Fourier series. Math. Comput., Apr. 1965, vol. 19, p. 297-301.
- SHOUSHENG HE, TORKELSON, M. Computing partial DFT for comb spectrum evaluation. IEEE Signal Processing Letters, June 1996.
- ZHANG, Q., KOKKELER, A. B. J, SMIT, G. J.M. An efficient FFT for OFDM based cognitive radio on a reconfigurable architecture. In IEEE International Conference on Communication. Glasgow (UK), June 2007.
- GOERTZEL, G. An algorithm for the evaluation of finite trigonometric series. Jan. 1958, Amer. Math. Monthly, vol. 65, p. 34-35.
- MINJIAN ZHAO, Study on multi-band, multi-rate, multi-mode software radio receivers. Ph.D Thesis, Zhejiang University, 2003.

Keywords: Cognitive radio, FBMC, transform decomposition, multistage filter banks, adaptive threshold

**K. Ruttik, K. Koufos, R. Jantti**
[references] [full-text]

Modeling of the Secondary System's Generated Interference and Studying of its Impact on the Secondary System Design

In this paper we study how much capacity a cellular secondary system can achieve if the interference to the TV system is kept under control. The interference is modeled and controlled in a slow fading environment. The secondary system's capacity is computed for the adjacent and for the co-channel (with respect to the TV channel). We study the behavior of the system capacity while changing the size of the no transmission area surrounding the TV coverage area. It turns out that for most of the secondary cell sizes the network with adjacent channel is in interference limited mode and the network with co-channel is in noise limited mode. Since in the co-channel we can not use very high power it is recommended to use in bigger cells only adjacent channel.

- HOVEN, N., SAHAI, A. Power scaling for cognitive radio. In 2005 International conference of Wireless Networks, Communications and Mobile Computing. Maui (HI, USA), 2005, vol. 1, p. 250 – 255.
- GHASEMI, A., SOUSA, E. S. Interference aggregation in spectrum- sensing cognitive wireless networks. IEEE Journal on Selected Top- ics in Signal Processing, 2008, vol. 2, no. 1, p. 41 – 56.
- HONG, X., WANG, C. X., TOMPSON, J. Interference modeling of cognitive radio networks. In IEEE 67th Vehicular Technology Con- ference: VTC2008-spring. Marina Bay (Singapore), 2008, p. 1851 – 1855.
- ALJUAID, M., YANIKOMEROGLU, H. A cumulant based charac- terization of the aggregated interference power in wireless networks. In IEEE 71st Vehicular Technology Conference: VTC2010-spring. Taipei (Taiwan), 2010, p. 1 – 5.
- WU, M., DEVROYE, N., TAROKH, V. On the primary exclusive region of cognitive networks. IEEE Transactions on Wireless Com- munications, 2009, vol. 8, no. 7, p. 3380 – 3385.
- HARRISSON, K., MISHRA, S. A., SAHAI, A. How much white space capacity is there. In IEEE Symposium on New Frontiers in Dy- namic Spectrum: DySPAN. Singapore, 2010, p. 1 – 10.
- WEI, Y., CIOFFI, J. M. On constant power water-ﬁlling. In IEEE International Conference on Communications: ICC. Helsinki (Fin- land), 2001, p. 1665 – 1669.

Keywords: Secondary spectrum usage, interference, capacity.

**N. Milosevic, Z. Nikolic, B. Dimitrijevic, B. Nikolic**
[references] [full-text]

The Effects of Interference Suppression by a Reconfigurable Structure at DSSS-DPSK Receiver

In this paper we show the performances of DSSS-DPSK receiver where the interference rejection circuit is reconfigurable and is using ξ-structure. The results will be shown for the case of packet, as well as for the continuous QPSK interference. The results show that the proposed reconfiguration circuit, in case of packet QPSK interference, significantly decreases the error probability, compared to the system using only ξ-structure. Also, in case of continuous interference, the reconfigurable structure has equally good performance, regardless of interference power and its bitrate.

- NIKOLIC, Z., DIMITRIJEVIC, B., MILOSEVIC N. Rejection of PSK interference in DS-SS/QPSK system using complex adaptive filter and nonlinear correlation receiver. Electronics Letters, 1997, vol. 33, no. 4, p. 268-270.
- HASAN, M. A., LEE, J. C., BHARGAVA, V. K. A narrowband interference canceller with adjustable centre weight. IEEE Trans. on Communications, 1994, vol. 42, no. 2/3/4, p. 877-880.
- GLISIC, S., NIKOLIC, Z., DIMITRIJEVIC, B. Adaptive self reconfigurable interference suppression schemes for CDMA wireless networks. IEEE Transactions on Communications, 1999, vol. 47, no. 4, p. 598-607.
- CHEN, K. C., PRASAD, R. Cognitive Radio Networks, London: John Wiley & Sons, 2009.
- HIGUCHI, K., FUJIWARA, A., SAWAHASHI, M. Multipath interference canceller for high-speed packet transmission with adaptive modulation and coding scheme in W-CDMA forward link. IEEE Journal on Selected Areas in Communications, 2002, vol. 20, no. 2, p. 419-432.

Keywords: Interference suppression, spread spectrum system, reconfiguration, error probability

**R. Pust, K. Burda**
[references] [full-text]

A New Technique of Frequency Hopping with Collision Avoidance

This article proposes a new technique of frequency hopping with collision avoidance (FH/CA). Currently there are well-known systems of frequency hopping which adapt their behavior based on previously measured data (such as PER) for individual channels. The FH/CA system adjusts its behavior based on the current occupancy of several test channels. Using a mathematical model, the performance of the newly proposed FH/CA technique is compared with the currently used techniques FH and AFH. Comparison criteria are the probability of a collision between an FH/CA communication system and a static or dynamic jammer (i.e. other FH or AFH systems).

- PUST, R., BURDA, K. Comparing performance of FH and AFH systems. International Journal of Computer Science and Network Security, 2010, vol. 10, no. 2, p. 82-85. ISSN: 1738- 7906.
- LAN/MAN Standards Committee of the IEEE Society, IEEE Std 802.15.1-2005, Part 15.1: Wireless MAC and PHY specifications for WPANs. [Online] Cited 2010-09-01. URL: http://standards .ieee.org /getieee802/download/802.15.1-2005.pdf.
- POPOVSKI, P., YOMO, H., PRASAD, R. Dynamic adaptive frequency hopping for mutually interfering wireless personal area network. Mobile Computing, IEEE Transactions, vol.5, no.8, p. 991-1003, Aug. 2006 doi: 10.1109/TMC.2006.114 URL: http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=164474 5&isnumber=34469.
- HSU, A.C.-C., WEI, D.S.L., KUO, C.-C.J., SHIRATORI, N., CHUNG-JU CHANG. Enhanced adaptive frequency hopping for wireless personal area networks in a coexistence environment. Global Telecommunications Conference GLOBECOM '07. 26-30 Nov. 2007, pp. 668-672. IEEE, doi: 10.1109/GLOCOM .2007.130 URL: http://ieeexplore.ieee.org/-stamp/stamp.jsp ?tp=&arnumber =4411040&isnumber=4410910.
- STABELLINI, L., SHI, L., AL RIFAI, A., ESPINO, J., MAGOULA, V. A new probabilistic approach for adaptive frequency hopping. IEEE 20th International Symposium on Personal, Indoor and Mobile Radio Communications, 13-16 Sept. 2009, p. 2147-2151, doi: 10.1109/PIMRC.2009.5450211 URL: http://ieeexplore.ieee.org/-stamp/stamp.jsp?tp=&arnumber= 5450211 &isnumber=5449713.
- PARK, K.-J, PARK, T. R., SCHMITZ, C. D., SHA, L. Design of robust adaptive frequency hopping for wireless medical telemetry systems. Communications, IET, January 22, 2010, vol.4, no.2, p. 178-191, doi: 10.1049/iet-com.2008.0693 URL: http://ieeexplore .ieee.org/stamp/stamp.jsp?tp=&arnumber=5383645&isnumber=53 83639.

Keywords: Frequency hopping, collision avoidance, static jammer, dynamic jammer.

**J. Blumenstein, Z. Fedra, V. Sebesta**
[references] [full-text]

Performance of Pilot Aided Channel Estimation Technique in 2D Spreading Based Systems

It has recently been observed that the combination of the OFDM (Orthogonal Frequency Division Multiplex) and the CDMA (Code Division Multiple Access) can achieve notably lower BER (Bit Error Rate) performance in comparison with OFDM itself. The paper reports on the actual topic of the efficient channel estimation in 2D spreading based systems e.q. VSF-OFCDM (Variable Spreading Factor - Orthogonal Frequency Multiple Acces). The different methods for acquisition of channel state information from pilot carriers are used. The simulations are made for different ETSI channel models.

- HARADA, H., PRASAD, R. Simulation and software radio for mo- bile communications. Boston: Artech House, 2002.
- FAZEL, K., KAISER, S. Multi-Carrier and Spread Spectrum Sys- tems. Chicester (UK), Wiley, 2003.
- HANZO, L., MUNSTER, M., CHOI, B. J., KELLER, T. OFDM and MC-CDMA for Boardband Multi-User Communications, WLANs and Broadcasting. Chichester (UK): Wiley, 2004.
- ZHENG, K., ZENG, G., WANG, W. Performance analysis for OFDM-CDMA with joint frequency-time spreading. IEEE Transac- tions on Broadcasting, 2005, vol. 51, no. 1, p. 144 – 148.
- HOEHER, P., KAISER, S., ROBERTSON, P. Two-dimensional pilot-symbol-aided channel estimation by Wiener ﬁltering. In Pro- ceedings of 1997 IEEE Int. Conf. Acoustics, Speech, and Signal Pro- cessing. Munich (Germany), 1997, p. 1845 – 1848.
- MAEDA, N., KISHIYAMA, Y., ATARASHI, H., SAWAHASHI, M. Variable spreading factor-OFCDM with two dimensional spreading that priorizes time domain spreading for forward link broadband wireless access. IEICE Transactions on Communications, 2005, vol. E88-B, no. 2.
- SESIA, S., TOUFIK, I., BAKER, M. (Eds.) LTE The UMTS Long Term Evolution: From Theory To Practice. Chichester (UK): Wiley, 2009.
- BLUMENSTEIN, J., FEDRA, Z. The characteristics of the 2D spreading based communication systems. In Proceedings of the 19th International Conference Radioelektronika 2009. Bratislava (Slo- vakia), 2009, p. 277 – 279.
- BLUMENSTEIN, J., FEDRA, Z. The PAPR and simple PAPR re- duction of the 2D spreading based communication systems. Radio- engineering, 2010, vol. 19, no. 1, p. 27 – 31.

Keywords: VSF-OFCDM, Two-dimensional spreading, Channel estimation, Channel state information, Pilot subcarriers, ETSI channel model, OFDM, CDMA

**Zs. Kollar, P. Horvath**
[references] [full-text]

Modulation Schemes for Cognitive Radio in White Spaces

In this paper we give an overview and a comparison of the possible waveforms for white space applications. Four physical layer schemes for cognitive radio are selected for study: Orthogonal Frequency Division Multiplexing (OFDM), DFT-Spread OFDM (DFTS-OFDM), Constant Envelope OFDM (CE-OFDM) and Filter Bank Multicarrier (FBMC). The comparison is mainly based on the side effects of various non-ideal analog components (power amplifier, local oscillator) and residual synchronization errors such as frequency offset. As we will show, each technique has different sensitivity to the various impairments. The comparisons will be performed via spectral density functions and bit error rates (BER).

- MITOLA, J., MAGUIREM, G. Q. Cognitive radio: Making software radios more personal. IEEE Personal Communications, 1999, vol. 6, no. 4. , p. 13 – 18.
- SHELLHAMMER, S. J., SADEK, A. K., WENYI ZHANG. Techni- cal challenges for cognitive radio in the TV white space spectrum. In Information Theory and Applications Workshop. San Diego (USA), 2009, p. 323 – 333.
- BORTH, D., EKL, R., OBERLIES, B., OVERBY, S. Considerations for successful cognitive radio systems in US TV white space, 3rd IEEE Symposium on Dynamic Spectrum Access Networks DySPAN 2008. Chicago (USA), 2008, p. 1 – 5.
- IEEE 802.22 Working Group on Wireless Regional Area Networks. [Online]. Available at: http://www.ieee802.org/22/
- CORDEIRO, C., CHALLAPALI, K., BIRRU, D., SHANKAR, S. IEEE 802.22: The ﬁrst worldwide wireless standard based on cogni- tive radios. In IEEE International Symposium on Dynamic Spectrum Access Networks DySPAN. Baltimore (USA), 2005, p. 328 – 337.
- Federal Communications Commission. Second Memorandum Opin- ion and Order: In the Matter of Unlicensed Opeartion in the TV Broadcast Band and Additional Spectrum for Unlicensed Devices Below 900 MHz in the 3 GHz Band. [Online]. 2010. Available at:http://www.fcc.gov/Daily Releases/Daily Business/2010/db0924/ FCC-10-174A1.pdf.
- VAN NEE, R., PRASAD R. OFDM for Wireless Multimedia Com- munications. Boston (USA): Artech House, 2000.
- THOMPSON, S. C., AHMED, A. U., PROAKIS, J. G., ZEIDLER, J. R., GEILE M. J. Constant-envelope OFDM. IEEE Transactions on Communication, 2008, vol. 56, no. 8., p. 1300 – 1312.
- HYUNG, G. M., JUNSUNG, L., GOODMAN, D. J. Single carrier FDMA for uplink wireless transmission. IEEE Vehicular Technology Magazine, 2006, vol. 1, no. 3, p. 30 – 38.
- VAIDYANATHAN, P. P. Multirate Systems and Filter Banks. Upper Saddle River (USA): Prentice-Hall, 1993.
- PAYARO, M., PASCUAL-ISERTE, A., NAJAR, M. Performance comparison between FBMC and OFDM in MIMO systems under channel uncertainty. In Proc. IEEE European Wireless EW 2010. Lucca (Italy), 2010.
- SALEH, A. Frequency-independent and frequency-dependent non- linear models of TWT ampliﬁers. IEEE Transactions on Communi- cation, 1981, vol. 29, p. 1715 – 1720.
- ALI, S., MARKARIAN, G., AL-AKAIDI, M. Frequency domain it- erative compensation of high power ampliﬁer non-linearity. In Mid- dle Eastern Multiconference on Simulation and Modelling MESM 2008. Amman (Jordan), 2008.
- HELD, I., KLEIN, O., CHEN, A., MA, V. Low complexity digi- tal IQ imbalance correction in OFDM WLAN receivers. In Vehic- ular Technology Conference VTC 2004-Spring. Milan (Italy), 2004, vol. 2, p. 1172 – 1176.
- POLLET, T., VAN BLADEL, M., MOENECLAEY, M. BER sensi- tivity of OFDM systems to carrier frequency offset and wiener phase noise. IEEE Transactions on Communiication, 1995, vol. 43, p. 191 – 193.

Keywords: Cognitive radio, physical layer, Orthogonal Frequency Division Multiplexing, DFT-spread OFDM, Constant Envelope OFDM, Filter Bank Multicarrier, synchronization error, white space.

**Z. Jing, B. Bai, X. Ma**
[references] [full-text]

Compensation-based Game for Spectrum Sharing in the Gaussian Interference Channel

This paper considers an optimization problem of sum-rate in the Gaussian frequency-selective channel. We construct a competitive game with an asymptotically optimal compensation to approximate the optimization problem of sum-rate. Once the game achieves the Nash equilibrium, all users in the game will operate at the optimal sum-rate boundary. The contributions of this paper are twofold. On the one hand, a distributed power allocation algorithm called iterative multiple waterlevels water-filling algorithm is proposed to efficiently achieve the Nash equilibrium of the game. On the other hand, we derive some sufficient conditions on the convergence of iterative multiple waterlevels water-filling algorithm in this paper. Through simulation, the proposed algorithm has a significant improvement of the performance over iterative water filling algorithm and achieves the close-to-optimal performance.

- HAN, T. S., KOBAYASHI, K. A new achievable rate region for the interference channel. IEEE Trans. on Information Theory, 1981, vol. 27, no. 1, p. 49–60.
- LESHEM, A., ZEHAVI, E. Cooperative game theory and the Gaussian interference channel. IEEE Journal on Selected Areas in Communications, 2008, vol. 26, no. 7, p. 1078-1088.
- LESHEM, A., ZEHAVI, E. Distributed coordination of spectrum and the prisoner’s dilemma. In Proceedings of the First IEEE International Symposium on New Frontiers in Dynamic Spectrum Access Networks, 2005, p. 94-100.
- LAUFER, A., LESHEM, A., MESSER, H. Game theoretic aspects of distributed spectral coordination with application to DSL networks. [Online] Cited 2006. Available at: arXiv:cs/0602014v1.
- SURIS, J. E., DASILVA, L. A. Cooperative game theory for distributed spectrum sharing. In Proceedings of the IEEE International Conference on Communications, 2007, p. 5282-8287.
- YU, W., GINIS, G., CIOFFI, J. M. Distributed multiuser power control for digital subscriber lines. IEEE Journal on Selected Areas in Communications, 2002, vol. 20, no. 5, p. 1105–1115.
- CENDRILLON, R., MOONEN, M., VERLIDEN, J. Optimal multi-user spectrum management for digital subscriber lines. In Proceedings of the IEEE International Conference on Communications, 2004, p. 1–5.
- CENDRILLON, R., YU, W, MARC, M. Optimal multiuser spectrum balancing for digital subscriber lines. IEEE Trans. on Communications, 2006, vol. 54, no. 5, p. 922-933.
- CENDRILLON, R., MOONEN, M. Iterative spectrum balancing for digital subscriber lines. In Proceedings of the IEEE International Conference on Communications, 2005, p. 1937– 1941.
- CENDRILLON, R., HUANG, J., MUNG, C. Autonomous spectrum balancing for digital subscriber lines. IEEE Trans. on Signal Processing, 2007, vol. 55, no. 8, p. 4241-4257.
- HUANG, J., CENDRILLON, R., MUNG, C. Autonomous spectrum balancing (ASB) for frequency selective interference channels. In Proceedings of the IEEE International Symposium on Information Theory, 2006, p. 610–614.
- TSIAFLAKIS, P., DIEHL, M., MOONEN, M. Distributed spectrum management algorithms for multiuser DSL networks. IEEE Trans. on Signal Processing, 2008, vol. 56, no. 10, p. 4825- 4843.
- HUANG, J., BERRY, R. A., HONIG, M. L. Distributed interference compensation for wireless networks. IEEE Journal on Selected Areas in Communications, 2006, vol. 24, no. 5, p. 1078- 1088.
- CHUNG, S. T. Transmission schemes for frequency selective Gaussian interference channel. Ph.D. dissertation, Stanford University, Nov. 2003.
- DEBREU, G. A social equilibrium existence theorem. National Academy of Sciences, 1952, vol. 38, p. 886–893.
- FAN, K. Fixed points and minimax theorems in locally convex topological linear spaces. National Academy of Sciences, 1952, vol. 38, p. 121–126.
- GLICKSBERG, I. L. A further generalization of the Kakutani fixed point theorem with application to Nash equilibrium points. National Academy of Sciences, 1952, vol. 38, p. 170–174.
- FUDENBERG, D., TIROLE, J. Game Theory. Cambridge: MA: MIT Press, 1991.
- PALOMAR, D. P., FONOLLOSA, J. R. Practical algorithms for a family of waterfilling solutions. IEEE Trans. on Signal Processing, 2005, vol. 53, no. 2, p. 686-695.
- SHUM, K. W., LEUNG, K. K., SUNG, C. W. Convergence of iterative waterfilling algorithm for Gaussian interference channels. IEEE Journal on Selected Areas in Communications, 2007, vol. 25, no. 6, p. 1091–1100.
- HORN, R. A., JOHNSON, C. R. Matrix Analysis. China Machine Press, 2005.

Keywords: Interference channel, Iterative water filling algorithm (IWFA), Power allocation, Game theory

**B. Hu, X. Yu, L. He, W. Lim, K. Yeo**
[references] [full-text]

Analysis and Design of Wideband Low Noise Amplifier with Digital Control

The design issues in designing low noise amplifier (LNA) for Software-Defined-Radio (SDR) are reviewed. An inductor-less wideband low noise amplifier aiming at low frequency band (0.2-2GHz) for Software-Defined-Radio is presented. Shunt-shunt LNA with active feedback is used as the first stage which is carefully optimized for low noise and wide band applications. A digitally controlled second stage is employed to provide an additional 12dB gain control. A novel method is proposed to bypass the first stage without degrading input matching. This LNA is fabricated in a standard 0.18 um CMOS technology. The measurement result shows the proposed LNA has a gain range of 6dB-18dB at high gain mode and -12dB-0dB at low gain mode, as well as a –3dB bandwidth of 2GHz. The noise figure (NF) is 3.5-4.5dB in the high gain setting mode. It consumes 20mW from a 1.8V supply.

- GIANNINI, V. et al. A 2-mm2 0.1-5GHz software-defined-radio receiver in 45nm digital CMOS. IEEE Journal of Solid State Circuits, 2009, vol. 44, no. 12, p. 3486 - 3498.
- BAGHERY, R. et al. A 800MHz-6GHz software-defined wireless receiver in 90nm CMOS. IEEE Journal of Solid State Circuits, 2009, vol. 41, no. 12, p. 2860 - 2876.
- B.STASZEWSKI, R. et al. All digital TX frequency synthesizer and discrete time receiver for bluetooth radio in 130nm CMOS. IEEE Journal of Solid State Circuits, 2004, vol. 39, no. 12, p. 2278 to 2291.
- CAFARO, G. et al. A 100MHz-2.5GHz direct conversion CMOS transceiver for SDR applications. In Proceedings of the 2007 Radio Frequency Integrated Circuits Symposium. Honululu, Hawaii, (U.S.A), 2007, p. 189 - 192.
- LIU, B., WANG, C., MA, M., GUO, S. An ultra low voltage and ultra low power 2.4GHz LNA design. Radioengineering, 2009, vol. 18, no. 4, p. 527 – 531.
- GODARA, B., FABRE, A. A new application of current conveyors: the design of wideband controllable low noise amplifiers Radioengineering, 2008, vol. 17, no. 4, p. 91 – 100.
- BEVILACQUA, A., NIKNEJAD, A. M. An ultra wideband CMOS low noise amplifier for 3.1-10.6GHz wireless receivers. IEEE Journal of Solid State Circuits, 2004, vol. 39, no. 12, p. 2259 – 2268.
- LI, X., SHEKEHAR, S., ALLSTOT, D. J. Gm-boosted common gate LNA and differential Colpitts VCO/QVCO in 0.18um CMOS. IEEE Journal of Solid State Circuits, 2005, vol. 40, no. 12, p. 2609 – 2619.
- SHEKEHAR, S., WALLING, J. S., ALLSTOT, D.J. Bandwidth extension techniques for CMOS amplifiers. IEEE Journal of Solid State Circuits, 2006, vol. 41, no. 11, p. 2424 – 2439.
- BRUCOLLERY, F., KLUMPRINK, E. A. M., NAUTA, B. Wideband CMOS low noise amplifier exploring thermal noise cancelling. IEEE Journal of Solid State Circuits, 2004, vol. 39, no. 2, p. 275 – 282.
- LIAO, C. F., LIU, S. I. A broadband noise cancelling LNA for 3.1- 10.6GHz UWB receiver. IEEE Journal of Solid State Circuits, 2007, vol. 42, no. 2, p. 329 – 339.
- BORRENMANS, J., WAMBACQ, P., SOENS, C., ROLAIN, Y., KUIJK, M. Low-area active feedback low noise amplifier design in scaled digital CMOS. IEEE Journal of Solid State Circuits, 2007, vol. 43, no. 11, p. 2422 – 2433.
- GRAY, P. R., HURST, P. J., LEWIS, S. H., MEYER, R. G. Analysis and Design of Analog Integrated circuits. 4th ed. John Wiley & Sons, Inc, 2001.
- AGGARWAL, S., KHOSROWBEYGI, A., DAANEN, A. A single-stage variable-gain amplifier with 70dB dynamic range for CDMA2000 transmit applications. IEEE Journal of Solid State Circuits, 2003, vol. 38, no. 6, p. 911 – 917.
- CARRARA, F., PALMISANO, G. High-dynamic-range VGA with temperature compensation and linear-in-dB gain control. IEEE Journal of Solid State Circuits, 2005, vol. 40, no. 10, p. 2019 – 2024.
- FU, C. T., LUONG, H. A CMOS linear-in-dB high linearity variable-gain amplifier for UWB receivers. In Proceedings of the 2007 IEEE Asia Solid State Circuits Conference. Jeju, (Korea), 2007, p. 103 - 106.
- XIAO, J., MEHR, I., MARTINEZ, J.S. A high dynamic range CMOS variable gain amplifier for mobile DTV tuner. IEEE Journal of Solid State Circuits, 2005, vol. 42, no. 2, p. 292 – 301.

Keywords: Low Noise Amplifier, Inductor-less, Software-Defined-Radio, Digital Gain Control

**O. Jakubov, P. Kovar, P. Kacmarik, F. Vejrazka**
[references] [full-text]

The Witch Navigator - A Low Cost GNSS Software Receiver for Advanced Processing Techniques

The developement of advanced GNSS signal processing algorithms such as multi-constellation, multi-frequency and multi-antenna navigation requires an easily reprogrammable software defined radio solution. Various receiver architectures for this purpose have been introduced. RF front-end with FPGA universal correlators on ExpressCard connected directly to PC was selected and manufactured. Such a~unique hardware combination provides the GNSS researchers and engineers with a~great convenience of writing the signal processing algorithms including tracking, acquisition and positioning in the Linux application programming interface and enables them to reconfigure the RF front-end easily by the PC program. With more of these ExpressCards connected to the PC, the number of the RF channels, correlators or antennas can be increased to further boost the computational power. This paper reveals the implementation aspects of the receiver, named the Witch Navigator, and~gives the key test results.

- KOVAR, P., KACMARIK P., VEJRAZKA, F. Low complex inter- operable GNSS signal processor and its performance. In Proceedings of IEEE/ION PLANS 2010 Position Location and Navigation Sym- posium [CD-ROM]. Palm Springs (CA, USA), 2010, p. 947 – 951.
- KOVAR, P., KACMARIK P., VEJRAZKA, F. Universal front end for software GNSS receiver. In Proceedings of 13th IAIN World Congress [CD-ROM]. Bergen (Norway), 2009, p. 1 – 6.
- KOVAR, P., VEJRAZKA, F., SEIDL, L., KACMARIK, P. Exper- imental software receiver of signals of satellite navigation systems. In 11th IAIN World Congress on Smart Navigation, Systems and Ser- vices. Berlin (Germany), 2003, p.391 – 394.
- HEIN, G. GNSS interoperability: Achieving a global system of systems or “Does everything have to be the same?”. [On- line]. Inside GNSS, 2006, vol. Jan/Feb, p. 57 – 60. Available at: http://www.insidegnss.com/auto/0106 Working Papers IGM.pdf .
- NORMARK, P. L., STAHLBERG, C. Hybrid GPS/Galileo real time software receiver. In Proceedings of ION GNSS 2005. Long Beach (CA, USA), 2005, p. 1906 – 1913.
- PANY, T., FORSTER, F., EISSFELLER, B. Real-time processing and multipath mitigation of high-bandwidth L1/L2 GPS signals with a PC-based software receiver. In Proceedings of ION GNSS 2004. Long Beach (CA, USA), 2004, p. 971 – 985.
- LEDVINA, B., PSIAKI, M., SHEINFELD, D., CERRUTI, A., POW- ELL, S., KINTER, P. Real-time software receiver tracking of GPS L2 civilian signals using a hardware simulator. In Proceedings of ION GNSS 2005. Long Beach (CA, USA), 2005, p. 1598 – 1610.
- SPACEK, J., PURICER, P. Front-end module for GNSS software receiver. In Proceedings of ELMAR 2006. Zadar (Croatia), 2006, p. 211 – 214.
- KOVAR, P., KACMARIK P., VEJRAZKA, F. High performance Galileo E5 correlator design. In Proceedings of 13th IAIN World Congress. Bergen (Norway), 2009, p. 1 – 8.
- Conﬁg preempt RT Patch (web page). [Online]. Cited 2010-10-09. Available at: https://rt.wiki.kernel.org/index.php/CONFIG PREEMPT RT Patch
- BORRE, K., AKOS, D. M., BERTELSEN, N., RINDER, P., JENSEN, S. H. A Software-Deﬁned GPS and Galileo Receiver. 1st ed. Boston: Birkhauser, 2007.
- KELLEY, C., CHENG, J., BARNES, J. Open source software for learning about GPS. In Proceedings of 15th Int. Tech. Meet- ing of the Satellite Division of the U.S. Inst. of Navigation [Online]. Portland (USA), 2002, p. 2524 – 2533. Available at: www.gmat.unsw.edu.au/snap/publications/opensourcegps.pdf
- MINDSHARE, INC., BUDRUK, R., ANDERSON, D., SHAN- LEY, T. PCI Express System Architecture. 4th ed. Boston (USA): Addison-Wesley, 2004.
- Galileo OS SIS ICD/D.0. Galileo Open Service - Signal in Space In- terface Control Document (OS SIS ICD) [Online]. 1st issue. Cited 2010-10-02. Available at: http://ec.europa.eu/enterprise/policies/ space/ﬁles/galileo/galileo os sis icd revised 2 en.pdf .
- ICD-GPS-200D. Navstar GPS Space Segment/Navigation User In- terfaces [Online]. Revision D. Cited 2010-02-11. Available at: http://www.gps.gov/technical/icwg/IS-GPS-200D.pdf .

Keywords: GNSS, Universal Correlator, GPS, Galileo, GLONASS, Compass, SDR

**Qihui Wu, Han Han, Jinlong Wang, Zhitao Zhao, Ze Zhang**
[references] [full-text]

Sensing Task Allocation for Heterogeneous Channels in Cooperative Spectrum Sensing

In the traditional centralized cooperative spectrum sensing, all secondary users sense the same channel. But, for a given channel, there exists detection performance diversity among all the users, due to the different signal-fading process. Involving the user with poor performance in cooperative sensing will not only deteriorate the detection correctness but also waste the sensing time. In the heterogeneous channels, the problem is even severe. A novel idea is to allocate the secondary users to sense different channels. We analyze the allocation problem before formulate it to be an optimization problem, which is a NP-hard problem. Then we propose the declined complexity algorithm in equal secondary user case and the two-hierarchy approach algorithm in unequal case. With the simulation, we verify the near optimality of the proposed algorithms and the advantage of the task allocation.

- HAYKIN, S. Cognitive radio: brain-empowered wireless communications. IEEE Journal on Selected Areas in Communication, 2005, vol. 23, no. 2, p. 201-220.
- DUAN, D., YANG, L., PRINCIPLE, J. C. Cooperative diversity of spectrum sensing for cognitive radio systems. IEEE Transactions on Signal Processing, 2010, vol. 58, no. 6.
- FAN, R., JIANG, H. Optimal multi-channel cooperative sensing in cognitive radio networks. IEEE Transactions on Wireless Communications, vol. 9, no. 3, 2010.
- SULA, A., ZHOU, C. A cooperative scheme for spectrum sensing in cognitive radio systems. Journal of Communications, vol. 4, no. 10, 2009.
- QUAN, Z., CUI, S., SAYED, A. H. Optimal linear cooperation for spectrum sensing in cognitive radio networks. IEEE J. Sel. Topics Signal Process, 2008, vol. 2, no. 1, p. 28–40.
- SU, H., ZHANG, X. Cross-layer based opportunistic MAC protocols for QoS provisioning over cognitive radio wireless networks. IEEE J. Sel. Area in Comm., 2008, vol. 26, no. 1, p. 118- 129.
- ALSHAMRANI, A., SHEN, X., et.al. A cooperative MAC with efficient spectrum sensing algorithm for distributed opportunistic spectrum networks. Journal of Communications, 2009, vol. 4, no. 10.
- SAU-HSUAN WU, CHAO-YUAN YANG, TINA HUANG, D.-H. Cooperative sensing of wideband cognitive radio--a multiple- hypothesis-testing approach. IEEE Transactions on Vehicular Technology, 2010, vol. 59, no. 4.
- LI, M., XU, Y., HU, J. A Q-learning based sensing task selection scheme for cognitive radio networks. In Proc. of the 1st International Conference on Wireless Communications & Signal Processing, 2009.
- STEVENSON, C. R., LEI, Z., HU, W., SHELLHAMMER, S. J., CALDWELL, W. IEEE 802.22: the first cognitive radio wireless regional area network standard. IEEE Communications Magazine, 2009.
- BOYD, S., VANDENBERGHE, L. Convex Optimization. Cam- bridge, UK: Cambridge University Press, 2004.
- CABRIC, D., TKACHENKO, A., BRODERSEN, R. W. Experimental study of spectrum sensing based on energy detection and network cooperation. In The 2nd Annual International Wireless Internet Conference (WICON), TAPAS Workshop, 2006.

Keywords: Cognitive radio, spectrum sensing, sensing task allocation

**H. Zhang, X. Wang, G. S. Kuo, T. M. Bohnert**
[references] [full-text]

Optimum Detection Location-Based Cooperative Spectrum Sensing in Cognitive Radio

Cognitive radio arises as a hot research issue in wireless communications recently, attributed to its capability of enhancing spectral efficiency and catering for the growing demand for bandwidth. As a good embodiment of cognitive radio’s unique feature, i.e. making use of every bit spectral resource, spectrum sensing plays a vital role in the implementation of cognitive radio. To alleviate negative effect on cooperative spectrum sensing brought by bit errors, we introduce a novel concept, i.e. Optimum Detection Location (ODL) and present two algorithms of different computational complexity for locating ODL, together with an ODL-Based cooperative spectrum sensing scheme, with the motivation to exploit the gain derived from geographic advantages and multiuser diversity. Numerical and simulation results both demonstrate that our proposed spectrum sensing scheme can significantly improve the sensing performance in the case of reporting channel with bit errors.

- FCC, Spectrum Policy Task Force Report. ET Docket No. 02-155, Nov. 2002.
- CORDEIRO, C., CHALLAPALI, K., BIRRU, D. IEEE 802.22: the first worldwide wireless standard based on cognitive radio. In Proc. of 1st IEEE Symp. New Frontiers in Dynamic Spectrum Access Networks, Baltimore, Maryland, Nov. 2005, p. 328-337.
- MISHRA, S. M., SAHAI, A., BRODERSEN, R. W. Cooperative sensing among cognitive radios. In Proc. of IEEE Int. Conf. on Communications. Istanbul (Turkey), 2006, vol. 4, p. 1658-1663.
- THOMOPOULOS, S. C. A., VISWANATHAN, R., BOUGOU- LIAS, D. C. Optimal decision fusion in multiple sensor systems. IEEE Trans. Aerosp. Electron. Syst., 1987, vol. 23, p. 644-653.
- VISWANATHAN, R., AALO, V. On counting rules in distributed detection. IEEE Trans. on Signal Processing, 1989, vol. 37, p. 772-775.
- CHEN, B., JIANG, R., KASETKASEM, T., et al. Channel aware decision fusion in wireless sensor networks. IEEE Trans. on Signal Processing, 2004, vol. 52, p. 3454-3458.
- CABRIC, D., MISHRA, S. M., BRODERSEN, R. W. Implementa- tion issues in spectrum sensing for cognitive radios. In Proceedings of Asilomar Conf. on Signals, Systems, and Computers. Pacific Grove (CA), 2004, vol. 1, p. 772-776.

Keywords: Cognitive radio, spectrum sensing, Wireless Region Area Network (WRAN), Optimum Detection Location (ODL).

**S. Tascioglu, O. Ureten, Z. Telatar**
[references] [full-text]

Impact of Noise Power Uncertainty on the Performance of Wideband Spectrum Segmentation

The objective of this work is to investigate the impact of noise uncertainty on the performance of a wideband spectrum segmentation technique. We define metrics to quantify the degradation due to noise uncertainty and evaluate the performance using simulations. Our simulation results show that the noise uncertainty has detrimental effects especially for low SNR users.

- HUR, Y., PARK, J., WOO, W., LIM, K., LEE, C.-H., KIM, H. S., LASKAR, J. A wideband analog multi-resolution spectrum sensing (MRSS) technique for cognitive radio (CR) systems. In IEEE Int. Symp. on Circuits and Syst., May 2006, p. 4090–4093.
- QUAN, Z., CUI, S., SAYED, A. H., POOR, H. V. Wideband spectrum sensing in cognitive radio networks. In IEEE Int. Conf. on Commun., May 2008, p. 901–906.
- TIAN, Z., GIANNAKIS, G. B. A wavelet approach to wideband spectrum sensing for cognitive radios. In 1st Int. Conf. on Cognitive Radio Oriented Wireless Networks and Commun., June 2006, p. 1–5.
- ESLAMI, M., SADOUGH, S. M.-S. Wideband spectrum sensing for cognitive radio via phase-field segmentation. In 6th Conference on Wireless Advanced (WiAD), 27-29 June 2010, p.1-5.
- TASCIOGLU, S., URETEN, O. Bayesian wideband spectrum segmentation for cognitive radios. In Proceedings of 18th International Conference on Computer Communications and Networks, ICCCN 2009, 3-6 Aug. 2009, p.1-6.
- SONNENSCHEIN, A., FISHMAN, P. M. Radiometric detection of spread-spectrum signals in noise of uncertain power. IEEE Transactions on Aerospace and Electronic Systems, 1992, vol. 28, no. 3, p. 654–660.
- TANDRA, R., SAHAI, A. SNR walls for signal detection. IEEE J. Sel. Topics Signal Process., Feb. 2008, vol. 2, no. 1, p. 4–17.
- CABRIC, D., TKACHENKO, A., BRODERSEN, R. W. Spectrum sensing measurements of pilot, energy, and collaborative detection. In Military Communications Conference, MILCOM 2006. Washington (DC, USA), 2006, p. 1–7.
- TAHERPOUR, A., NASIRI-KENARI, M., GAZOR, S. Invariant wideband spectrum sensing under unknown variances. IEEE Transactions on Wireless Communications, May 2009, vol.8, no. 5, p.2182-2186.
- LOPEZ-VALCARCE, R., VAZQUEZ-VILAR, G. Wideband spectrum sensing in cognitive radio: Joint estimation of noise variance and multiple signal levels. In IEEE 10th Workshop on Signal Processing Advances in Wireless Communications, SPAWC '09, 21-24 June 2009, p.96-100.
- TAHERPOUR, A., NASIRI-KENARI, M., GAZOR, S. Multiple antenna spectrum sensing in cognitive radios. IEEE Transactions on Wireless Communications, 2010, vol. 9, no. 2, p. 814-823.
- LOPEZ-VALCARCE, R., VAZQUEZ-VILAR, G., SALA, J. Multiantenna spectrum sensing for cognitive radio: overcoming noise uncertainty. In The 2nd International Workshop on Cognitive Information Processing CIP 2010, June 2010, p. 310-315.
- PRIESTLEY, M. B. Spectral analysis and time series. Academic Press Limited, London, 1994.
- GREEN, P. J. Reversible jump Markov chain Monte Carlo computation and Bayesian model determination. Biometrika, 1995, vol. 82, no. 4, p. 711–732.

Keywords: Cognitive radio, spectrum sensing, wideband RF spectrum monitoring, noise uncertainty, Markov chain Monte Carlo

**S. M. Kamruzzaman, Md. Abdul Hamid, M. Abdullah-Al-Wadud**
[references] [full-text]

An Energy Efficient MAC Protocol for QoS Provisioning in Cognitive Radio Ad Hoc Networks

The explosive growth in the use of real-time applications on mobile devices has resulted in new challenges to the design of medium access control (MAC) protocols for ad hoc networks. In this paper, we propose an energy efficient cognitive radio (CR) MAC protocol for QoS provisioning called ECRQ-MAC, which integrate the spectrum sensing at physical (PHY) layer and the channel-timeslots allocation at MAC layer. We consider the problem of providing QoS guarantee to CR users as well as to maintain the most efficient use of scarce bandwidth resources. The ECRQ-MAC protocol exploits the advantage of both multiple channels and TDMA, and achieves aggressive power savings by allowing CR users that are not involved in communication to go into sleep mode. The proposed ECRQ-MAC protocol allows CR users to identify and use the unused frequency spectrum of licensed band in a way that constrains the level of interference to the primary users (PUs). Our scheme improves network throughput significantly, especially when the network is highly congested. The simulation results show that our proposed protocol successfully exploits multiple channels and significantly improves network performance by using the licensed spectrum opportunistically and protects QoS provisioning over cognitive radio ad hoc networks.

- MITOLA, J. III. Cognitive radio: An integrated agent architecture for software defined radio. Ph.D. Thesis, KTH Royal Inst. of Technology, May, 2000.
- AKYILDIZ, I. F., LEE, W. Y., VURAN, M., MOHANTY, S. Next generation/dynamic spectrum access/cognitive radio wireless networks: A survey. Comput. Netw., Sep. 2006, vol. 50, no. 13, pp. 2127-2159.
- THOMAS, R. W., DASILVA, L. A., MACKENZIE, A. B. Cogni- tive networks. In Proc. IEEE DySPAN, Nov. 2005, pp. 352-360.
- LIU, Y., GUO, L., MA, H., JIANG, T. Energy efficient on-demand multipath routing protocol for multi-hop ad hoc networks. In Proc. IEEE ISSSTA, pp. 572-576, Aug. 2008.
- RANIWALA, A., CHIUEH, T. Architecture and algorithms for an IEEE 802.11-based multi-channel wireless mesh network. In Proc. IEEE Infocom, Aug. 2005, vol. 3 pp. 2223-2234.
- RANIWALA, A., GOPALAN, K., CHIUEH, T. Centralized channel assignment and routing algorithms for multi-channel wireless mesh networks. ACM Mob. Comp. and Commu. Review (MC2R), vol. 8, no. 2, pp. 50–65, Apr. 2004.
- HAYKIN, S. Cognitive radio: Brain-empowered wireless communications. IEEE J. Sel. Areas Commun., Feb. 2005, vol. 23, no. 2, pp. 201-220.
- DEVROYE, M., MITRAN, P., TAROHK, V. Limits on commu- nications in a cognitive radio channel. IEEE Commun. Mag., Jun. 2006, pp. 44-49.
- CABRIC, D., MISHRA, S., BRODERSEN, R. Implementation issues in spectrum sensing for cognitive radios. In Proc. ACSSC, Nov. 2004.
- CHOI, N., PATEL, M., VENKATESAN, S. A full duplex multi- channel MAC protocol for multi-hop cognitive radio networks. In Proc. CrownCom, 2006, pp. 1–5.
- IEEE 802.11 Working Group, Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications. IEEE 802.11 Standard, 1997.
- IEEE 802.22 Working Group on Wireless Regional Area Networks. http://www.ieee802.org/22/, 2009.
- SHU, T., CUI, S., KRUNZ, M. Medium access control for multi- channel parallel transmission in cognitive radio networks. In Proc. IEEE Globecom, Nov. 2006.
- BANY SALAMEH, H., KRUNZ, M., YOUNIS, O. Distance and traffic-aware channel assignment in cognitive radio networks. In Proc. IEEE SECON, Jun. 2008.
- SANKARANARAYANAN, S., PAPADIMITRATOS, P., MISHRA, A., HERSHEY, S. A bandwidth sharing approach to improve licensed spectrum utilization. In Proc. IEEE DySPAN, Nov. 2005, pp. 279-288.
- SABHARWAL, A., KHOSHNEVIS, A., KNIGHTLY, E. Oppor- tunistic spectral usage: bounds and a multi-band CSMA/CA proto- col. IEEE/ACM Trans. Netw., 2007, vol. 15, no. 3, p. 533-545.
- MA, L., HAN, X., SHEN, C.-C. Dynamic open spectrum sharing MAC protocol for wireless ad hoc networks. In Proc. IEEE DySPAN, Nov. 2005, pp. 203-213.
- YUAN, Y., BAHL, P., CHANDRA, R., CHOU, P., FERRELL, J., MOSCIBRODA, T., NARLANKA, S., WU, Y. Knows: Kognitive networking over white spaces. In Proc. IEEE DySPAN, Apr. 2007, pp. 416-427.
- CORDEIRO, C., CHALLAPALI, K. C-MAC: A cognitive MAC protocol for multichannel wireless networks. In Proc. IEEE DySPAN, Apr. 2007, pp. 147-157.
- SU, H., ZHANG, X. Cognitive radio based multichannel MAC protocols for wireless ad hoc networks. In Proc. IEEE Globecom, Nov. 2007, pp. 4857-4861.
- SU, H., ZHANG, X. CREAM-MAC: An efficient Cognitive Radio-EnAbled Multi-channel MAC Protocol for wireless networks. In Proc. WOWMOM, Jun. 2008, pp. 1-8.
- SU, H., ZHANG, X Cross-layer based opportunistic MAC protocols for QoS provisionings over cognitive radio wireless networks. IEEE J. Sel. Areas Commun., 2008, vol. 26, no. 1, pp. 118-129.
- SILVIUS, M. D., MACKENZIE, A. B., BOSTIAN, C. W. Rendezvous MAC protocols for use in cognitive radio networks. In Proc. IEEE MILCOM, Oct. 2009, pp. 1-7.
- BANY SALAMEH, H. A., KRUNZ, M. M., YOUNIS, O. MAC protocol for opportunistic cognitive radio networks with soft guarantees. IEEE Trans. Mob. Comp., Oct. 2009, vol. 8, no. 10, pp. 1339-1352.
- TIMMERS, M., POLLIN, S., DEJONGHE, A., VAN DER PERRE, L., CATTHOOR, F. A distributed multichannel MAC protocol for multihop cognitive radio networks. IEEE Trans. Veh. Tech., 2010, vol. 59, no. 1, pp. 446-459.
- ZHAO, Q., TONG, L., SWAMI, A. Decentralized cognitive MAC for dynamic spectrum access. In Proc. IEEE DySPAN, Nov. 2005, pp. 224- 232.
- HSU, A. C.-C., WEI, D. S. L., KUO, C.-C. J. A cognitive radio MAC protocol using statistical channel allocation for wireless ad hoc networks. In Proc. IEEE WCNC, Mar. 2007, pp. 105-110.
- KONDAREDDY, Y. R., AGRAWAL, P. Synchronized MAC protocol for multi-hop cognitive radio networks. In Proc. IEEE ICC, May 2008, pp. 3198-3202.
- KAMRUZZAMAN, S. M. An energy efficient multichannel MAC protocol for cognitive radio ad hoc networks. Int. J. Commun. Netw. Info. Sec. (IJCNIS), Aug. 2010, vol. 2, no. 2, pp. 112-119.
- KAMRUZZAMAN, S. M. CR-MAC: A multichannel MAC protocol for cognitive radio ad hoc networks. Int. J. Comp. Netw. Commun. (IJCNC), Sep. 2010, vol. 2, no. 5, pp. 1-14.
- LE, L., HOSSAIN, E. OSA-MAC: A MAC protocol for opportunistic spectrum access in cognitive radio networks. In Proc. IEEE WCNC, Mar. 2008, pp. 1426-1430.
- RANIWALA, A., CHIUEH, T. Architecture and algorithms for an IEEE 802.11-based multi-channel wireless mesh network. In Proc. IEEE Infocom, Mar. 2005, pp. 2223–2234.
- GUPTA, P., KUMAR, P. R. The capacity of wireless networks. IEEE Trans. Information Theory, Mar 2000, vol. 46, no. 2, pp. 388-404.
- THOPPIAN, M., VENKATESAN, S., PRAKASH, R., CHANDRASEKARAN, R. MAC-layer scheduling in cognitive radio based multi-hop wireless networks. In Proc. WoWMoM, Jul. 2006, pp. 191-202.
- ZHANG, J., ZHOU, G., HUANG, C., SON, S. H., STANKOVIC, J. A. TMMAC: An energy efficient multi-channel MAC protocol for ad hoc networks. In Proc. IEEE ICC, Jun. 2007, pp. 3554- 3561.
- CHEE HOCK NG. Queuing Modeling Fundamentals. New York: John Wiley & Sons Ltd, 1996.
- BIANCHI, G. Performance analysis of the IEEE 802.11 distributed coordinated function. IEEE J. Sel. Areas Commun., Mar. 2000, vol. 18, no. 3, pp. 353-547.
- CANO, J.-C., MANZONI, P. A performance comparison of energy consumption for mobile ad hoc network routing protocols. In Proc. MASCOTS, 2000, pp. 57-63.

Keywords: Cognitive radio, multichannel MAC, energy efficiency, QoS, ad hoc networks, frequency spectrum, TDMA, channel sensing.

**J. Trdlicka, Z. Hanzalek**
[references] [full-text]

Distributed Multi-Commodity Network Flow Algorithm for Energy Optimal Routing in Wireless Sensor Networks.

This work proposes a distributed algorithm for energy optimal routing in a wireless sensor network. The routing problem is described as a mathematical problem by the minimum-cost multi-commodity network flow problem. Due to the separability of the problem, we use the duality theorem to derive the distributed algorithm. The algorithm computes the energy optimal routing in the network without any central node or knowledge of the whole network structure. Each node only needs to know the flow which is supposed to send or receive and the costs and capacities of the neighboring links. An evaluation of the presented algorithm on benchmarks for the energy optimal data flow routing in sensor networks with up to 100 nodes is presented.

- XIAO, L., JOHANSSON, M., BOYD, S. Simultaneous routing and resource allocation via dual decomposition. IEEE Transactions on Communications, 2004, vol. 52, no. 7, p. 1136–1144.
- TRDLICKA, J., JOHANSSON, M., HANZALEK, Z. Optimal ﬂow routing in multi-hop sensor networks with real-time constraints through linear programming. In 12th IEEE International Conference on Emerging Technologies and Factory Automation ETFA07. Patras (Greece), 2007, p. 924 – 931.
- BERTSEKAS, D. P., GALLAGER, R. Data Networks. Upper Saddle River (USA): Prentice Hall, 2004.
- CHIANG, M. Geometric programming for Communication Systems - Foundations and Trends in Communications and Information The- ory. Hanover (USA): now Publishers Inc., 2005.
- PIORO, M., MEDHI, D. Routing, Flow, and Capacity Design in Communication and Computer Networks. San Francisco (USA): Morgan Kaufmann, 2004.
- BERTSEKAS, D. P. Network Optimization: Continuous and Dis- crete Models. Nashua (USA): Athena Scientiﬁc, 1998.
- OUOROU, A., MAHEY, P., VIAL, P. A survey of algorithms for convex multicommodity ﬂow problems. Management Science, 2000, vol. 46, no. 1, p. 126 – 147.
- BOYD, S., VANDENBERGHE, L. Convex Optimization. Cam- bridge (United Kingdom): Cambridge University Press, 2004.
- JOHANSSON, M., XIAO, L. Cross-layer optimization of wireless networks using nonlinear column generation. IEEE Transactions on Wireless Communications, 2006, vol. 5, no. 2, p. 435 – 445.
- PALOMAR, D., CHIANG, M. A tutorial on decomposition methods for network utility maximization. IEEE Journal on Selected Areas in Communications, 2006, vol. 24, no. 8, p. 1439 – 1451.
- PALOMAR, D., CHIANG, M. Alternative decompositions for dis- tributed maximization of network utility: Framework and applica- tions. In 25th IEEE International Conference on Computer Commu- nications INFOCOM 2006. Barcelona (Spain), 2006, p. 1 – 13.
- CHIANG, M., LOW, S., CALDERBANK, A., DOYLE, J. Layering as optimization decomposition: A mathematical theory of network architectures. Proceedings of the IEEE, 2007, vol. 95, no. 1, p. 255 – 312.
- JOHANSSON, B., SOLDATI, P., JOHANSSON, M. Mathematical decomposition techniques for distributed cross-layer optimization of data networks. IEEE Journal on Selected Areas in Communications, 2006, vol. 24, no. 8, p. 1535 – 1547.
- JOHANSSON, B., JOHANSSON, M. Primal and dual approaches to distributed cross-layer optimization. In 16th IFAC World Congress. Prague (Czech Republic), 2005.
- NAMA, H., CHIANG, M., MANDAYAM, N. Utility-lifetime trade- off in self-regulating wireless sensor networks: a cross-layer de- sign approach. In IEEE International Conference on Communica- tions ICC 2006. Istanbul (Turkey), 2006, p. 3511 – 3516.
- TSITSIKLIS, J., BERTSEKAS, D. Distributed asynchronous opti- mal routing in data networks. IEEE Transactions on Automatic Con- trol, 1986, vol. 31, no. 4, p. 325 – 332.
- LOW, S., LAPSLEY, D. Optimization ﬂow control. I. basic algo- rithm and convergence. IEEE/ACM Transactions on Networking, 1999, vol. 7, no. 6, p. 861 – 874.
- RESENDE, M. G. C., PARDALOS, P. M. Handbook of Optimization in Telecommunications. Berlin: Springer, 2006.

Keywords: Routing, In-network distributed algorithms, Multi-commodity network flow, Dual decomposition

**H. Henniger, A. Ludwig, J. Horwath**
[references] [full-text]

Performance Bounds of DPSK and OOK for Low Elevation Optical LEO Downlinks

Optical wireless LEO downlinks are seen as an emerging solution to increase available bandwidth to multigigabits per second. One of the biggest challenges is the impact of the atmosphere on the optical signal. The atmosphere causes time-varying link degradation due to index of refraction turbulence, especially at low elevation angles. Since the influence of the turbulence for low elevation downlinks is hardly investigated we perform numerical propagation simulations in order to achieve reliable received signal statistics. These results are further utilized to evaluate performance bounds of optical wireless systems from an information theory perspective. We focus on the two most common optical wireless systems, i.e. NRZ-DPSK and NRZ-OOK. This work shows that under low elevation angles acceptable quality of service can only be reached with high code rates.

- PERLOT, N., KNAPEK, M., GIGGENBACH, D., HORWATH, J., BRECHTELSBAUER, M., TAKAYAMA, Y., JONO, T. Results of the optical downlink experiment KIODO from OICETS satellite to optical ground station oberpfaffenhofen (OGS-OP). In Free-Space Laser Communication Technologies XIX. San Jose (USA), 2007.
- ANDREWS, L. C., PHILLIPS, R. L., HOPEN, C. Y. Laser Beam Scintillation with Applications. SPIE Optical Engineering Press, 2001.
- ANDREWS, L. C., PHILLIPS, R. L. Laser Beam Propagation through Random Media, Second Edition. SPIE Press Monograph Vol. PM152, 2005.
- YURA, H. T., MCKINLEY, W. G. Optical scintillation statistics for IR ground-to-space laser communication systems. Applied Optics, 1983, vol. 22, no. 21, p. 3353 – 3358.
- GIGGENBACH, D., HENNIGER, H. Fading-loss assessment in at- mospheric free-space optical communication links with on-off key- ing. Optical Engineering, 2008, vol. 47.
- VETELINO, F. S., YOUNG, C., ANDREWS, L. Fade statistics and aperture averaging for gaussian beam waves in moderate-to-strong turbulence. Applied Optics, 2007, vol. 46, no. 18, p. 3780 – 3789.
- HENNIGER, H., EPPLE, B., HAAN, H. Maritime mobile optical- propagation channel measurements. In Proceedings of IEEE Inter- national Conference on Communications 2010. Cape Town (South Africa), 2010.
- AL-HABASH, M., ANDREWS, L., PHILLIPS, R. Mathematical model for the irradiance probability density function of a laser beam propagating through turbulent media. Optical Engineering, 2001, vol. 40, p. 1554 – 1562.
- ANDREWS, L. C., PHILLIPS, R. L., HOPEN, C. Y., AL-HABASH, M. A. Theory of optical scintillation. Journal of the Optical Society of America A, 1999, vol. 16, no. 6, p. 1417 – 1429.
- GIGGENBACH, D., HORWATH, J., EPPLE, B. Optical satellite downlinks to optical ground stations and high-altitude platforms. In 16th Mobile and Wireless Communication Summit. Budapest (Hun- gary), 2007, p. 1 – 4.
- NISTAZAKIS, H., KARAGIANNI, E., TSIGOPOULOS, A., FAFALIOS, M., TOMBRAS, G. Average capacity of optical wire- less communication systems over atmospheric turbulence channels. Journal of Lightwave Technology, 2009, vol. 27, no. 8, p. 974 – 979.
- SANDALIDIS, H., TSIFTSIS, T. Outage probability and ergodic ca- pacity of free-space optical links over strong turbulence. Electronics Letters, 2008, vol. 44, no. 1, p. 46 – 47.
- FARID, A., HRANILOVIC, S. Channel capacity and non-uniform signalling for free-space optical intensity channels. IEEE Journal on Selected Areas in Communications, 2009, vol. 27, no. 9, p. 1553 – 1563.
- FARID, A. A., HRANILOVIC, S. Outage capacity optimization for free-space optical links with pointing errors. Journal of Lightwave Technology, 2007, vol. 25, no. 7, p. 1702 – 1710.
- ANGUITA, J., DJORDJEVIC, I., NEIFELD, M., VASIC, B. Shan- non capacities and error-correction codes for optical atmospheric tur- bulent channels. Journal of Optical Networking, 2005, vol. 4, no. 9, p. 586 – 601.
- KLYATSKIN, V. I., TATARSKI, V. I. The parabolic equation approx- imation for propagation of waves in a medium with random inhomo- geneities. Sov. Phys. JETP31, 1970, p. 335 – 339.
- BAKER, G. J. Gaussian beam weak scintillation: low-order turbu- lence effects and applicability of the Rytov method. Journal of the Optical Society of America A, 2006, vol. 23, no. 2, p. 395 – 417.
- HORWATH, J., PERLOT, N. Determination of statistical ﬁeld pa- rameters using numerical simulations of beam propagation through optical turbulence. Proc. of SPIE, 2004, vol. 5338.
- FLECK, J. F. M. Time-dependent propagation of high energy laser beams through the atmosphere. Applied Physics, 1976, vol. 10, no. 2, p. 129 – 160.
- ANDREWS, L. C., PHILLIPS, R. L. Laser Beam Propagation through Random Media. SPIE Press, 1998.
- AGRAWAL, G. P. Fiber-Optic Communication Systems. Wiley, 2002.
- GNAUCK, W. Optical phase-shift-keyed transmission. Journal of Lightwave Technology, 2005, vol. 23, no. 1, p. 115 – 130.
- GNAUCK, A. H., RAYBON, G., BERNASCONI, P. G., LEUTHOLD, J., DOERR, C. R., STULZ, L. W. 1-Tb/s (6x170.6Gb/s) transmission over 2000-km NZDF using OTDM and RZ-DPSK format. IEEE Photonics Technology Letters, 2003, vol. 15, no. 11, p. 1618 – 1620.
- SINSKY, J. H., ADAMIECKI, A., GNAUCK, A., BURRUS, C., LEUTHOLD, J., WOHLGEMUTH, O., UMBACH, A. 42.7 Gb/s in- tegrated balanced optical front end with record sensitivity. In Optical Fiber Communications Conference. Atlanta (USA), 2003.
- SHANNON, C. E. A mathematical theory of communications. Bell Syst. Tech. J., 1948, vol. 27, p. 379 – 423.

Keywords: Free-space optical communications, channel capacity, index of refraction turbulence, fading, LEO downlink, system performance

**F. Nadeem, T. Javornik, E. Leitgeb, V. Kvicera, G. Kandus**
[references] [full-text]

Continental Fog Attenuation Empirical Relationship from Measured Visibility Data

Free Space Optics (FSO) has the great potential for future communication applications. However, weather influenced reduced availability had been the main cause for its restricted growth. Among different weather influences fog plays the major role. A new model generalized for all FSO wavelengths, has been proposed for the prediction of continental fog attenuation using visibility data. The performance of the proposed model has been compared with well known models for measured attenuation data of Continental fog. The comparison has been performed in terms of Root Mean Square Error (RMSE).

- ACAMPORA, A. Last mile by laser. Scientific American, July 2002.
- FLECKER, B., GEBHART, M., LEITGEB, E., SHEIKH MUHAMMAD, S., CHLESTIL, C. Results of attenuation- measurements for Optical Wireless Channel under dense fog conditions regarding different wavelengths. In Proc. SPIE, 2006, vol. 6303.
- NADEEM, F., LEITGEB, E. Dense maritime fog attenuation prediction from measured visibility data. Radioengineering, 2010, vol. 19, no. 2, p. 223-227.
- GEBHART, M., LEITGEB, E., AL NABOULSI, M., SIZUN, H. Measurements of light attenuation at different wavelengths in dense fog conditions for FSO applications. COST 270 Short Term Scientific Mission 7 Report , 2004.
- KRUSE, P. W. et al. Elements of Infrared Technology: Generation, Transmission and Detection. New York: J. Wiley and Sons, 1962.
- KIM, I., MCARTHUR, B., KOREVAAR, E. Comparison of laser beam propagation at 785 and 1550 nm in fog and haze for opt. wireless communications. In Proc. SPIE, 2001, vol. 4214, p. 26 to 37.
- AL NABOULSI, M., SIZUN, H., DE FORNEL, F. Fog attenuation prediction for optical and infrared waves. Optical Engineering, 2004, vol. 43, no. 2, p. 319-329.
- BOUCHET, O., MARQUIS, T., CHABANE, M., AL NABOULSI, M., SIZUN, H. FSO and quality of service software prediction. In Proc. SPIE, 2005, vol. 5892, p. 01-12.
- MCCLAVE, J. T., DIETRICH, F. H., SINCICH, T. Statistics. 7th ed. Prentice Hall, 1997.

Keywords: FSO, attenuation, simulation, fog, model comparison.

**X. Zhao, S. Huang**
[references] [full-text]

Influence of Sea Surface Roughness on the Electromagnetic Wave Propagation in the Duct Environment

This paper deals with a study of the influence of sea surface roughness on the electromagnetic wave propagation in the duct environment. The problem of electromagnetic wave propagation is modeled by using the parabolic equation method. The roughness of the sea surface is computed by modifying the smooth surface Fresnel reflection coefficient to account for the reduction in the specular reflection due to the roughness resulting from sea wind speed. The propagation model is solved by the mixed Fourier split-step algorithm. Numerical experiments indicate that wind-driven roughened sea surface has an impact on the electromagnetic wave propagation in the duct environment, and the strength is intensified along with the increment of sea wind speeds and/or the operating frequencies. In a fixed duct environment, however, proper disposition of the transmitter could reduce these impacts.

- YAN, H. J., FU, Y., HONG, Z. J. Introduction to Modern Atmospheric Refraction. Shanghai: Science and Educational Press, 2006.
- HE, G. Y., LU, C. C., HONG, J. C., DENG, H. Computation and Measurement of Electromagnetic Scattering. Peking: National Defence Industry Press, 2006.
- VALTR, P., PECHAC, P. Tropospheric refraction modeling using ray-tracing and parabolic equation. Radioengineering, 2005, vol. 14, no. 4, p. 98-104.
- KUTTLER, J. R., DOCKERY, G. D. Theoretical description of the parabolic approximation/ Fourier split-step method of representing electromagnetic propagation in the troposphere. Radio Science, 1991, vol. 26, no. 2, p. 381-393.
- HITNEY, H. V. Hybrid ray optics and parabolic equation methods for radar propagation modelling. In Proc. IEE Int. Conf. Radar. Brighton (U.K.), 1992, p. 58-61.
- BARRIOS, A. E. Parabolic equation modelling in horizontally inhomogeneous environments. IEEE Transactions on Antennas and Propagation, 1992, vol. 40, no. 7, p. 791-797.
- BARRIOS, A. E. A terrain parabolic equation model for propagation in the troposphere. IEEE Transactions on Antennas and Propagation, 1994, vol. 42, no. 1, p. 90-98.
- GRABNER, M, KVICERA, V. Clear-air propagation modelling using parabolic equation method. Radioengineering, 2003, vol. 12, no. 4, p. 50-54.
- OZGUN, O. Recursive two-way parabolic equation approach for modelling terrain effects in tropospheric propagation. IEEE Transactions on Antennas and Propagation, 2009, vol. 57, no. 9, p. 2706-2714.
- VALTR, P., PECHAC, P., KVICERA, V., GRABNER, M. A terrestrial multiple-receiver radio link experiment at 10.7 GHz – comparisons of results with parabolic equation calculations. Radioengineering, 2010, vol. 19, no. 1, p. 117-121.
- GUILLET, N., FABBRO, V., BOURLIER, C., COMBES, P. F. Low grazing angle propagation above rough surface by the parabolic wave equation. In Geoscience and Remote Sensing Symposium, 2003.
- DOCKERY, G. D., KUTTLER, J. R. An improved impedance-boundary algorithm for Fourier split-step solution of the parabolic wave equation. IEEE Transactions on Antennas and Propagation, 1996, vol. 44, no. 12. p. 1592-1599.
- YANG, X. Q., ZHAO, J. S., WANG, Y. Electromagnetic Field and Electromagnetic Wave. Peking: National Defence Industry Press, 2002.
- AMENT, W. S. Toward a theory of reflection by a rough surface. In Proc. IRE. 1953, vol. 41, p. 142-146.
- MILLER, A. R., BROWN, R. M., VEGH, E. New derivation for rough surface reflection coefficient and for the distribution of seawave elevations. In IEE Proc, 1984, vol. 131, no. 2, p. 114-116.
- HITNEY, H. V., VIETH, R. Statistical assessment of evaporation duct propagation. IEEE Transactions on Antennas and Propagation, 1990, vol. 38, no. 6, p. 794-799.

Keywords: Electromagnetic wave propagation, parabolic equation, sea wind speed, evaporation duct.

**V. Prajzler, O. Lyutakov, I. Huttel, J. Spirkova, V. Jerabek**
[references] [full-text]

Design of Polymer Wavelength Splitter 1310 nm/1550 nm Based on Multimode Interferences

We report about design of 1x2 1310/1550 nm optical wavelength division multiplexer based on polymer waveguides. The polymer splitter was designed by using RSoft software based on beam propagation method. Epoxy novolak resin polymer was used as core waveguides layer, silicon substrate with silica layer was used as buffer layer and polymethylmethacrylate was used as protection cover layer. The simulation shows that the output energy for the fundamental mode is 67.1 % for 1310 nm and 67.8 % for 1550 nm wavelength.

- PAIAM, M. R., MacDONALD, R. I. Compact planar 980/1550 nm wavelength multi/demultiplexer based on multimode interference. IEEE Photonics Technology Letters, 1995, vol. 7, no. 10, p. 1180- 1182.
- LIN, K. C., LEE, W. Y. Guided wave 1.3/1.55 μm wavelength divison multiplexer based on multimode interference. Electronics Letters, 1996, vol. 32, no. 14, p. 1259-1261.
- IBRAHIM, M. H., KASSIM, N. H., MOHAMMAD, A. B., SHUH-YING, L., MEE-KOY, C. A novel 1 x 2 multimode interference optical wavelength filter based on photodefinable benzocyclobutene (BCB 4024-40) polymer. Micro. and Opt. Technology Letters, 2007, vol. 49, no. 5, p. 1024-1028.
- TRIKI, S., NAJJAR, M., REZIG, H., CATHERINE, L. Simulation and modelization of multimode interference demultiplexer by using BPM method. In Int. Conf. on Information and Communication, 2008, vol. 1-5, p. 1873-1877.
- SOLDANO, L. B., PENNNINGS, E. C. M. Optical multi-mode interference devices based on self-imaging - principles and applications. Journal of Lightwave Technology, 1995, vol. 13, no. 4, p. 615–627.
- SAM, Y. L., WON, Y. H.: A compact and low-loss 1 x 2 wavelength MUX/DEMUX based on a multimode-interference coupler using quasi state. Microwave and Optical Technology Letters, 2004, vol. 41, no. 2, p. 615–627.

Keywords: Multimode Interference couplers, polymer optical waveguides, Epoxy Novolak Resin, beam propagation method

**L. Subrt, D. Grace, P. Pechac**
[references] [full-text]

Controlling the Short-Range Propagation Environment Using Active Frequency Selective Surfaces

This paper deals with a new approach to the control of the propagation environment in indoor scenarios using intelligent walls. The intelligent wall is a conventional wall situated inside a building, but equipped with an active frequency selective surface and sensors. The intelligent wall can be designed as a self-configuring and self-optimizing autonomous part of a collaborative infrastructure working within a high-capacity mobile radio system. The paper shows how such surfaces can be used to adjust the electromagnetic characteristics of the wall in response to changes in traffic demand, monitored using a network of sensors, thereby controlling the propagation environment inside the building. Some of the potential problems (mainly controlling coverage and interference) relating to an increased usage of wireless systems both inside and outside buildings are discussed and possible solutions using intelligent walls with the active FSS are suggested. The positive influence of intelligent walls on system performance is shown and results obtained from the simulations are shown and discussed.

- GOLDSMITH, A. Wireless Communications. Cambridge University Press, 2005. New York:
- PATRICK, D., MORROW, R. Wireless Network Coexistence. McGraw-Hill Professional, 2004.
- SAUNDERS, S., ARAGON, A. Antennas and Propagation for Wireless Communication Systems. Wiley & Sons, 2007.
- MITOLA, J. Cognitive Radio Architecture. New York: Wiley & Sons, 2006.
- MUNK, B. A. Frequency Selective Surfaces: Theory and Design. Wiley & Sons, 2000.
- CHANG, K., SANG, K., JOONG, Y. Y. Equivalent circuit modeling of active frequency selective surfaces. In Radio and Wireless Symposium, 2008, p. 663-666.
- KIANI, G. I., ESSELLE, K. P., WEILY, A. R., FORD, K. L. Active frequency selective surface using PIN diodes. In Antennas and Propagation Society Int. Symposium. 2007, p. 4525-4528.
- SUNG, G. H. H., SOWERBY, K. W., NEVE, M. J., WILLIAMSON, A. G. A frequency-selective wall for interference reduction in wireless indoor environments. IEEE Antennas and Propagation Magazine, 2006, vol. 48, p. 29-37.
- TEO, P. T., LUO, X. F., LEE, C. K. Transmission of convoluted periodic loop element with selective reflection. Applied Physics Letters, 2004, vol. 85, p. 1454-1456.
- PECHAC, P., KLEPAL, M. Effective indoor propagation predictions. In Vehicular Technology Conference. 2001, p. 1247- 1250.
- SUBRT, L., PECHAC, P. Semi-deterministic propagation model for subterranean galleries and tunnels. IEEE Transactions on Antennas and Propagation, Accepted May, 2010.
- RYAN, W. T., DANIEL, H. F., LUIZ, A. D., ALLEN, B. M. Cognitive networks: adaptation and learning to achieve end-to-end performance objectives. IEEE Communications Magazine, 2006, vol. 44, p. 51-57.
- THOMAS, R. W., DASILVA, L. A., MACKENZIE, A. B. Cognitive networks. In First IEEE International Symposium on New Frontiers in Dynamic Spectrum Access Networks DySPAN 2005. 2005, p. 352-360.
- HUINING, H., YANIKOMEROGLU, H., FALCONER, D. D., PERIYALWAR, S. Range extension without capacity penalty in cellular networks with digital fixed relays. In IEEE Global Telecommunications Conf. GLOBECOM '04. 2004, p. 3053-3057.

Keywords: Frequency Selective Surfaces, cognitive networks, intelligent infrastructure, indoor propagation modeling

**O. Baran, M. Kasal**
[references] [full-text]

Modeling of the Simultaneous Influence of the Thermal Noise and the Phase Noise in Space Communication Systems

Our work deals with studies of a noise behavior in space communication systems. Two most important noise types the additive thermal noise and the multiplicative phase noise, respectively, are included. A simple model of the narrowband communication system is created and simulated in the Ansoft Designer system simulator. The additive thermal noise is modeled as AWGN in a communication channel. The phase noise is produced in transmitter and receiver oscillators. The main intention is to investigate the receiver filter bandwidth decrease effect on powers of both noise types. Results proposed in this paper show that for defined system conditions and for a certain filter bandwidth value, the power of the multiplicative phase noise equals to the additive thermal noise power. Another decrease of the filter bandwidth causes the phase noise power exceeding. To demonstrate the noise behavior transparently, input system parameters are properly selected. All simulation results are documented by theoretical calculations. Simulation outcomes express a good coincidence with presumptions and calculations.

- SPACEK, J., KASAL, M. The low rate telemetry transmission simulator. Radioegineering, 2007, vol. 16, no. 4, p. 24-31.
- PROAKIS, J. G. Digital Communications (4th Edition). New York: McGraw-Hill, 2001. p. 1024.
- LEE, T. H., HAJIMIRI, A. Oscillator phase noise: A tutorial. IEEE Journal of Solid-State Circuits, 2000, vol. 35, no. 3, p. 326 – 336.
- MEYR, H., MOENECLAEY, M., FECHTEL, S. A. Digital Communication Receivers: Synchronization, Channel Estimation and Signal Processing. New Jersey: John Willey & Sons, 1998.
- KASAL, M. Radio Relay and Satellite Communication. Lecture notes. Brno: MJ Servis, 2003. ISBN 80-214-2288-2. (In Czech.)
- BARAN, O., KASAL, M. Modeling of the phase noise in space communication systems. Radioengineering, 2010, vol. 19, no. 1, p. 141-148.
- VASILESCU, G. Electronic Noise and Interfering Signals: Principals and Applications. Berlin: Springer, 2005. 728 pages.
- ROBINS, W. P. Phase Noise in Signal Sources. London: Peter Peregrinus Ltd, 2007. ISBN: 987-0-86341-026-0.
- RILEY, J. Handbook of Frequency Stability Analysis. Beaufort: Hamilton Technical Services, 2007. [Online] Cited 2010-10-06. Available at: http://www.stable32.com/Handbook.pdf.
- CHANG, K. Encyclopedia of RF and Microwave Engineering. New Jersey: John Willey & Sons, 2005.

Keywords: Ansoft Designer, thermal noise, AWGN, phase noise, FIR filter, noise bandwidth.

**P. Tosovsky, D. Valuch**
[references] [full-text]

Improvement of RF Vector Modulator Performance by Feed-forward Based Calibration

RF Vector Modulator enables independent control of a narrowband RF signal amplitude and phase. Unfortunately practical realization of an analog vector modulator suffers from misbalances and imperfections in the I and Q signal paths. Use of a feed-forward based calibration can compensate for them and significantly improve RF performance and control accuracy of a real vector modulator. Achieved improvements and results on a small series of vector modulator based phase shifters using feed-forward calibration are presented.

- BOUSSARD, D., BOHL, T., LINNECAR, T., WEHRLE, U. Non integer harmonic number acceleration of lead ions in the CERN SPS. In Proceedings of 16th Particle Accelerator Conference, 1995, p.1506-1508. [Online] Cited 2010-05-13. Available at: http://epaper.kek.jp/p95/ARTICLES/FAE/FAE10.PDF
- CASTANEDA, L. G., USTARIZ, J. C., KNAPP, E. Phase shifter system using vector modulation for phased array radar applications. In Proceedings of 49th IEEE International Midwest Symposium on Circuits and Systems MWSCAS '06, 2006, vol. 2, p. 688-692. ISBN: 1-4244-0172-0.
- CHUA, M., MARTIN, K. W. 1 GHz programmable analog phase shifter for adaptive antennas. In Proceedings of the IEEE Custom Integrated Circuits Conference’98, 1998, p. 71-74. ISBN: 0-7803- 4292-5.
- BERNSTEIN, R. W., HEIDE, C. F. Optimisation of signal phase split in vector modulator phase shifters. In IEEE Proceedings - Circuits, Devices and Systems, 1994, vol. 141, no. 3, p. 207-209. ISSN: 1350-2409.
- XINPING HUANG, CARON, M. A novel type-based vector modulator self-calibration technique. In Proceedings of IEEE International Symposium on Circuits and Systems ISCAS ’09, 2009, p. 924-927. ISBN: 978-1-4244-3827-3.
- BOUMAIZA, S., JING LI, GHANNOUCHI, F. M. Implementa- tion of an adaptive digital/RF predistorter using direct LUT synthesis. IEEE MTT-S International Microwave Symposium Digest, 2004, vol. 2, p. 681-684. ISSN: 0149-645X.
- Analog Devices, Norwood (USA), ADL5390 RF/IF Vector Multiplier Rev.0 (datasheet). 24 pages. [Online] Cited 2010-04-13. Available at: http://www.analog.com/static/imported- files/Data_Sheets/ADL5390.pdf.
- CERN, Switzerland, SPS Phase Shifter documentation (interactive documentation). [Online] Cited 2010-04-13. Available at: https://edms.cern.ch/nav/EDA-01934/EDA-01934-V2-0

Keywords: Phase shifter, vector modulator, calibration, feed-forward, phase error, set point

**P. Vsetula, Z. Raida**
[references] [full-text]

Sierpinski-Based Conical Monopole Antenna

Planar Sierpinski monopole exhibits a multi-band behavior, but its parameters in operation frequency bands are not optimal. By mapping the Sierpinski monopole on a conical surface, a symmetrical three-dimensional (3-D) structure is obtained. In this way, a larger bandwidth and a better radiation pattern is achieved. The symmetrical 3D Sierpinski-based monopole is an original contribution of this paper. In the paper, different versions of the conical Sierpinski-based monopole are designed, and results of simulations performed in CST Microwave Studio are mutually compared. Then, the simulated versions of the conical monopole are optimized according to specified criteria. The optimized conical Sierpinski-based monopole is manufactured and its properties are experimentally verified. Results of measuring the Sierpinski-based conical monopole antenna are published here for the first time.

- MANDELBROT, B. B. The Fractal Geometry of Nature. New York: W.H. Freeman and Company, 1982.
- PUENTE, C., ROMEU, J., POUS, R., CARDAMA, A. On the behavior of the Sierpinski multiband fractal antenna. IEEE Transactions on Antennas and Propagation, 1998, vol. 46, no. 4, p. 517 - 524.
- BEST, S. R. A multiband conical monopole antenna derived from a modified Sierpinski gasket. IEEE Antennas and Wireless Propagation Letters, 2003, vol. 2, p. 205 - 207.
- VSETULA, P., RAIDA, Z. Sierpinski conical monopole antennas. In Proceedings of the 15th Conference on Microwave Techniques COMITE. Brno (Czech Republic), 2010, p. 55 – 57.
- PROKOPEC, J., HANUS, S. Mobile Communication Systems. Textbook, Brno: University of Technology, 2008, p. 10 - 11.

Keywords: Sierpinski monopole, multi-band antenna, conformal antenna, fractals, conical monopole.

**V. Schejbal, J. Pidanic**
[references] [full-text]

Broadband Approximations for Doubly Curved Reflector Antenna

The broadband approximations for shaped-beam doubly curved reflector antennas with primary feed (rectangular horn) producing uniform amplitude and phase aperture distribution are derived and analyzed. They are very valuable for electromagnetic compatibility analyses both from electromagnetic interference and susceptibility point of view, because specialized more accurate methods such as physical optics are only used by antenna designers. To allow quick EMC analyses, typical values, beamwidth changes, sidelobe levels and aperture efficiencies are given for frequency changes approximately up to four times operating frequency. A comparison of approximated and measured patterns of doubly curved reflector antennas shows that the given approximation could be reliably used for analyses of pattern changes due to very broad frequency changes.

- SILVER, S. Microwave Antenna Theory and Design. New York: McGraw-Hill, 1949, Sec. 6.4, 10.10 and 13.8.
- MILLIGAN, T. A. Modern Antenna Design. Hoboken: John Wiley & Sons, 2005, Sec. 7-1, 7-5, 8-20.3, p. 52, 56, 214.
- VOLAKIS, J. L. Antenna Engineering Handbook. New York: McGraw-Hill, 2007, Sec. 15.5.
- PIDANIC, J., CERMAK, D., SCHEJBAL, V. Gain estimation of doubly curved reflector antenna. Radioengieering, 2008, vol. 17, no. 3, p. 38 – 41.
- KUPCAK, D. Microwave antenna calculation using National Elliott 803 B computer. In Radar Technology in Transport. Pardubice (Czech Republic), 1965, p. 20 – 34.
- KUPCAK, D., SCHEJBAL, V. Calculating the radiation pattern of doubly curved reflector antenna (in Czech). Slaboproudy obzor, 1975, vol. 36, no. 12, p. 567 – 571.
- SCHEJBAL, V., KUPCAK, D. A Survey of programs for calculating microwave antennas with the aid of a computer (in Czech). Slaboproudy obzor, 1976, vol. 37, no. 3, p. 117 – 122.
- CARBERRY, T. F. Analysis theory for the shaped beam doubly curved reflector antenna. IEEE Transactions on Antennas and Propagation, 1969, vol. 17, no. 2, p. 131 – 138.
- SCHEJBAL, V. Czech radar technology. IEEE Transactions on Aerospace & Electronics Systems, 1994, vol. 30, no. 1, p. 2– 17.
- BEZOUSEK, P., SCHEJBAL, V. Radar technology in the Czech Republic. IEEE Aerospace and Electronic Systems Magazine, 2004, vol. 19, no. 8, p. 27 – 34.
- KUPCAK, D. Formulating the radiation characteristics of the primary radiator in a microwave antenna for computer calculation (in Czech). Slaboproudy obzor, 1974, vol. 35, no. 3, p. 111 – 117.
- KUPCAK, D. Evaluation of antenna radiation patterns by the generalized trapezoidal method. Tesla Electronics, 1974, vol. 7, no. 2, p. 43 – 50.
- ABRAMOWITZ, M., STEGUN, I. A. (eds.) Handbook of Mathematical Functions. New York: Dover Publications, 1965, p. 231, 887.
- SCHEJBAL, V. Integration point number estimation for Gaussian method of Fourier transform integration (in Czech). Slaboproudy obzor, 1980, vol. 41, no. 1, p. 51.
- SCHEJBAL, V. Calculating the radiation characteristics of a double-curved mirror antenna - an estimate of point number of the Gaussian integration method (in Czech). Slaboproudy obzor, 1981, vol. 42, no. 8, p. 391 – 396.
- SCHEJBAL, V., BEZOUSEK, P., HAJEK, M. Accuracy of Gauss method for antenna pattern calculations. In Proceedings on the World Congress "Aviation in the XXI-st Century". Kiev (Ukraine), 2003, p. 5.53 – 5.56.
- RUAN, Y. Z., ZHOU, H. J., LIN, J. Radiation analysis of reflector antennas by Gaussian beam method. In Proceedings of the International Symposium on Antennas and Propagation Society. 1995, vol. 2, p. 909 – 911.
- KRIZ, J., KRCMAR, V., PIDANIC, J., SCHEJBAL, V. Antenna beamwidth control. IEEE Antennas and Propagation Magazine, 2010, vol. 52, no. 1, p. 163 – 170.
- SCHEJBAL V. Directivity of planar antennas, IEEE Antennas and Propagation Magazine, 1999, vol. 41, no. 2, p. 60 - 62.
- DOLECEK, R., SCHEJBAL, V. Estimation of antenna gain. IEEE Antennas and Propagation Magazine, 2009, vol. 51, no. 1, p. 124 – 125.
- DRINOVSKY, J., SVACINA, J., RAIDA, Z. Simple models of EMI filters for low frequency range. Radioengineering, 2008, vol. 17, no. 3, p. 8 – 14.

Keywords: Broadband approximation, radiation patterns, shaped-beam reflector antennas, doubly curved reflector, electromagnetic compatibility

**E. Demircioglu, M. H. Sazli**
[references] [full-text]

Behavioral Modeling of a C-Band Ring Hybrid Coupler Using Artificial Neural Networks

Artificial Neural Networks (ANNs) gained importance on the RF microwave (MW) design area and behavioral modeling of MW components in the past few decades. This paper presents a cost effective neural network (NN) approach to overcome design, modeling and optimization problems of an 180deg ring hybrid coupler operating in C-Band. The proposed NN model is trained by data sets obtained from electromagnetic (EM) simulators and neural test results are compared with simulator findings to determine the network accuracy. Moreover, necessary trade-offs are applied to improve the networks’ performance. Finally correlation factors, which are defined as comparison criteria between EM-simulator and proposed neural models, are calculated for each trade-off case.

- WANG, F., ZHANG, Q. J. Knowledge based neural models for microwave design. IEEE Transactions on Microwave Theory and Techniques, 1997, vol. 45, no. 12, p. 2333 – 2343.
- CREECH, G. L., PAUL, B. J., LESNIAK, C. D., JENKINS, T. J., CALCATERA, M. C. Artificial neural networks for accurate microwave CAD applications. IEEE International Microwave Symposium Digest, San Francisco, CA, 1996, p. 733 - 736.
- WATSON, P. M., GUPTA, K. C. Design and optimization of CPW circuits using EM-ANN models for CPW components. IEEE Transactions on Microwave Theory and Techniques, 1997, vol. 45, no. 12, p. 2515 - 2523.
- ZAABAB, A. H., ZHANG, Q. J., NAKHLA, M. S. Neural network modeling approach to circuit optimization and statistical design. IEEE Transactions on Microwave Theory and Techniques, 1995, vol. 43, no. 6, p. 1349 – 1358.
- WATSON, P. M., GUPTA, K. C., MAHAJAN, R. L. Development of knowledge based artificial neural network models for microwave components. IEEE International Microwave Symposium Digest, Baltimore, MD, 1998, p. 9 - 12.
- KOTHAPALLI, G. Artificial neural networks as aids in circuit design. Microelectronics Journal, 1995, vol. 26, p. 569 - 578.
- HARKOUSS, Y., ROUSSET, J., CHEHADE, H., BARATAUD, D., TEYSSIER, J. P. Modeling microwave devices and circuits for telecommunications system design. In Proceedings of IEEE International Conference on Neural Networks. Anchorage (USA, AK), 1998, p. 128 - 133.
- VELUSWAMI, A., NAKHLA, M. S., ZHANG, Q. J. The application of neural networks to EM based simulation and optimization of interconnects in high speed VLSI circuits. IEEE Transactions on Microwave Theory and Techniques, 1997, vol. 45, no. 5, p. 712 - 723.
- HORNG, T., WANG, C., ALEXOPOULOS, N. G. Microstrip circuit design using neural networks. IEEE International Microwave Symposium Digest, Atlanta, GA, 1993, p. 413 - 416.
- BURRASCANO, P., DIONIGI, M., FANCELLI, C., MONGIARDO, M. A neural network model for CAD and optimization of microwave filters. IEEE International Microwave Symposium Digest, Baltimore, MD, 1998, p. 13 - 16.
- RIZZI, P. A. Microwave Engineering Passive Circuits. Prentice Hall, 1988.
- BAHL, B., GUPTA G. Microstrip Lines and Slotlines. Artech House, 1996
- SVACINA, J. New method for analysis of microstrip with finite- width ground plane. Microwave and Optical Technology Letters, vol. 48, no. 2, 2006, p. 396-399.
- WHEELER, H. A. Transmission-Line Properties of Parallel Strips Separated by a Dielectric Sheet. IEEE Transactions on Microwave Theory and Techniques, 1965, vol. 13, no. 2, p. 172-185.
- SCHNEIDER, M. V. Microstrip lines for microwave integrated circuits, The Bell System Technical Journal, 1969, vol. 48, p. 1421-1444.
- HAMMERSTAD, E., JENSEN, Ø. Accurate models for microstrip computer-aided design. Symposium on Microwave Theory and Techniques, 1980, p. 407-409.
- SELVAN, P. T., RAGHAVAN, S. Multilayer perceptron neural analysis of edge coupled and conductor-backed edge coupled coplanar waveguides. Progress in Electromagnetics Research B, 2009, vol. 17, p. 169-185.
- KAYA, S., TURKMEN, M., GUNEY, K., YILDIZ C. Neural models for the elliptic- and circular-shaped microshield lines. Progress in Electromagnetics Research B, 2008, vol. 6, p. 169- 181.
- TURKMEN, M., YILDIZ C. Quasi-static models based on artificial neural networks for calculating the characteristic parameters of multilayer cylindrical coplanar waveguide and strip line. Progress in Electromagnetics Research B, 2008, vol. 3, p. 1- 22.
- WANG, F., DEVABHAKTUNI, V. K., XI, C., ZHANG, Q. J. Neural network structures and training algorithms for RF and microwave applications. International Journal of Microwave and Millimeter-Wave Computer-Aided Engineering, 1999, vol. 9, no. 3, p. 216 – 240.
- LEVENBERG, K. A method for the solution of certain nonlinear problems in least squares. Quarterly of Applied Mathematics, 1963, vol. 11, p. 431- 441.
- POLAK, E., RIBIERE, G. Note sur la convergence de methods de directions conjuguees. Reveu Francaise d’Informatique et de Recherche Operationnelle, 1969, p. 16-35.
- HAYKIN, S. Neural Networks – A Comprehensive Foundation. Prentice Hall, 1999.
- FLETCHER, R., REEVES, C. M., Function minimization by con- jugate gradients. The Computer Journal, 1964, vol. 7, p. 149-154.
- MOLLER, M. F. A scaled conjugate gradient algorithm for fast supervised learning. Neural Networks, 1993, vol. 6, p. 525-533.
- REIDMILLER, M., BRAUN, H., A direct adaptive method for faster backpropagation learning: The Rprop algorithm. In Proceedings of the IEEE International Conference on Neural Networks. San Francisco (USA), 1993, p. 586-591.

Keywords: Artificial Neural Networks (ANN), Ring Hybrid Coupler (RHC), C-band, optimization, behavioral modeling

**J. W. Horng**
[references] [full-text]

DVCCs Based High Input Impedance Voltage-Mode First-Order Filters Employing Grounded Capacitor and Resistor

A voltage-mode high input impedance first-order highpass, lowpass and allpass filters using two differential voltage current conveyors (DVCCs), one grounded capacitor and one grounded resistor is presented. The highpass, lowpass and allpass signals can be obtained simultaneously from the circuit configuration. The suggested filter uses a canonical number of passive components without requiring any component matching condition. The simulation results confirm the theoretical analysis.

- HORNG, J. W., HOU, C. L., CHANG, C. M., CHOU, H. P., LIN, C. T. High input impedance voltage-mode universal biquadratic filter with one input and five outputs using current conveyors. Circuits, Systems and Signal Processing, 2006, vol. 25, pp. 767 to 777.
- MINAEI, S., YUCE E. All-grounded passive elements voltage- mode DVCC-based universal filters. Circuits, Systems and Signal Processing, 2010, vol. 29, pp. 295-309.
- BHUSHAN, M., NEWCOMB, R. W. Grounding of capacitors in integrated circuits. Electronic Letters, 1967, vol. 3, pp.148-149.
- GUPTA, S. S., SENANI, R. Realisation of current-mode SRCOs using all grounded passive elements. Frequenz, 2003, vol. 57, pp. 26-37.
- PAL, K. Realization of current conveyor all-pass networks. International Journal of Electronics, 1981, vol. 50, pp. 165-168.
- HORNG, J. W. Current conveyors based allpass filters and quadrature oscillators employing grounded capacitors and resistors. Computers and Electrical Engineering, 2005, vol. 31, pp. 81-92.
- SOLIMAN, A. M. Inductorless realization of an all-pass transfer function using the current conveyor. IEEE Transactions on Circuit Theory, 1973, vol. CT-20, pp. 80-81.
- HIGASHIMURA, M. Realization of all-pass networks using a current conveyor. International Journal of Electronics, 1988, vol. 65, pp. 249-250.
- KHAN, I. A., MAHESHWARI, S. Simple first order all-pass section using a single CCII. International Journal of Electronics, 2000, vol. 87, pp. 303-306.
- KUMAR, P., KESKIN, A. U., PAL, K. Wide-band resistorless all- pass sections with single element tuning. International Journal of Electronics, 2007, vol. 94, pp. 597-604.
- SALAWU, R. I. Realization of an allpass transfer function using the second generation current conveyor. Proceedings of the IEEE, 1980, vol. 68, pp. 183-184.
- CICEKOGLU, O., KUNTMAN, H., BERK, S. All-pass filters using a single current conveyor. International Journal of Electronics, 1999, vol. 86, pp. 947-955.
- IBRAHIM, M. A., KUNTMAN, H., CICEKOGLU, O. First-order all-pass filter canonical in the number of resistors and capacitors employing a single DDCC. Circuits, Systems, and Signal Processing, 2003, vol. 22, pp. 525-536.
- HORNG, J. W., HOU, C. L., CHANG, C. M., LIN, Y. T., SHIU, I. C., CHIU, W. Y. First-order allpass filter and sinusoidal oscillators using DDCCs. International Journal of Electronics, 2006, vol. 93, pp. 457-466.
- IBRAHIM, M. A., KUNTMAN, H., OZCAN, S., SUVAK, O., CICEKOGLU, O. New first-order inverting-type all-pass sections including canonical forms. Electrical Engineering, 2004, vol. 86, pp. 299-301.
- CHEN, H. P., WU, K. H. Grounded-capacitor first-order filter using minimum components. IEICE Transactions on Fundamentals, 2006, vol. E89-A, pp. 3730-3731.
- KESKIN, A. U., PAL, K., HANCIOGLU, E. Resistorless first order all-pass filter with electronic tuning. AEU International Journal of Electronics and Communications, 2008, vol. 62, pp. 304-306.
- BIOLEK, D., BIOLKOVA, V. First-order voltage-mode all-pass filter employing one active element and one grounded capacitor. Analog Integrated Circuits and Signal Processing, in press.
- TANAPHATSIRI, C., JAIKLA, W., SIRIPRUCHYANUN, M. An electronically controllable voltage-mode first-order all-pass filter using only single CCCDTA. In Proceedings of the 2008 International Symposium on Communications and Information Technologies ISCIT. (Lao), 2008, pp. 305–309.
- METIN, B., CICEKOGLU, O., PAL, K. Voltage mode allpass filter with a single current differencing buffered amplifier. In Proceedings of the 51st Midwest Symposium on Circuits and Systems MWSCAS. Knoxville, TN (USA), 2008, pp. 734-737.
- MAHESHWARI, S. Voltage-mode all-pass filters including minimum component count circuits. Active and Passive Electronic Components, 2007, Article ID 79159, pp. 1-5.
- PAL, K. Modified current conveyors and their applications. Microelectronics Journal, 1989, vol. 20, pp. 37-40.
- KUMAR, P., KESKIN, A. U., PAL, K. DVCC-based single element controlled oscillators using all-grounded components and simultaneous current-voltage mode outputs. Frequenz, 2007, vol. 61, pp. 141-144.
- MAHESHWARI, S. High input impedance VM-APSs with grounded passive elements. IET Circuits, Devices and Systems, 2007, vol. 1, pp. 72-78.
- MAHESHWARI, S. High input impedance voltage-mode first- order all-pass sections. International Journal of Circuits Theory and Applications, 2008, vol. 36, pp. 511-522.
- MINAEI, S., YUCE, E. Novel voltage-mode all-pass filter based on using DVCCs. Circuits, Systems and Signal Processing, 2010, vol. 29, pp. 391-402.
- ELWAN, H. O., SOLIMAN, A. M. Novel CMOS differential voltage current conveyor and its applications. IEE Proceedings- Circuits Devices and Systems, 1997, vol. 144, pp. 195-200.
- HORNG, J. W., HOU, C. L., CHANG, C. M., CHOU, H. P., LIN, C. T., WEN, Y. H. Quadrature oscillators with grounded capacitors and resistors using FDCCIIs. ETRI Journal, 2006, vol. 28, pp. 486-494.

Keywords: Current conveyors, first-order, allpass filter, analog circuit design

**S. Minaei, E. Yuce**
[references] [full-text]

New Squarer Circuits and a Current-Mode Full-Wave Rectifier Topology Suitable for Integration

In this paper, three squarer configurations and a current-mode (CM) full-wave rectifier circuit are suggested. The first and second squarer configurations respectively use two PMOS and two NMOS transistors while the third one employs three PMOS and one NMOS transistors. A CM full-wave rectifier with high output impedance current is developed. All of the proposed circuits provide several advantages such as low number of components and less power consumption. The proposed circuits are simulated using SPICE program to demonstrate their performance and workability.

- FIKOS, G., SISKOS, S. Analogue CMOS vector normalisation circuit. Electronics Letters, 1999, vol. 35, no. 25, p. 2197-2198.
- LOPEZ-MARTIN, A. J., RAMIREZ-ANGULO, J., CHINTHAM, R., CARVAJAL, R. G. Class AB CMOS analogue squarer circuit. Electronics Letters, 2007, vol. 43, no. 20, p. 336-338.
- WILSON, B. Recent developments in current conveyors and current-mode circuits. IEE Proceedings Circuits, Devices and Systems, 1990, vol. 137, no. 2, p. 63-77.
- TOUMAZOU, C., LIDGEY, F. J., HAIGH, D. G. Analog IC Design: The Current-Mode Approach. London: Peter Peregrinus, 1990.
- ROBERTS, G. W., SEDRA, A. S. All current-mode frequency selective circuits. Electronics Letters, 1989, vol. 25, no. 12, p. 759- 761.
- BIOLEK, D., HANCIOGLU, E., KESKIN, A. U. High- performance current differencing transconductance amplifier and its application in precision current-mode rectification. AEU- International Journal of Electronics and Communications, 2008, vol. 62, no. 2, p. 92-96.
- WANG, Z. Novel pseudo RMS current converter for sinusoidal signals using a CMOS precision current rectifier. IEEE Transactions on Instrumentation and Measurement, 1990, vol. 39, no. 4, p. 670-671.
- RAMIREZ-ANGULO, J., CARVAJAL, R. G., TOMBS, J., TORRALBA, A. Very low-voltage class AB CMOS and bipolar precision current rectifiers. Electronics Letters, 1999, vol. 35, no. 22, p. 1904-1905.
- CHANG, C.-C., LIU, S.-I. Current-mode full-wave rectifier and vector summation circuit. Electronics Letters, 2000, vol. 36, no. 19, p. 1599-1600.
- WILSON, B., MANNAMA, V. Current-mode rectifier with improved precision. Electronics Letters, 1995, vol. 31, no. 4, pp. 247-248.
- SEDRA, A. S., SMITH, K. C. Microelectronic Circuits. Fifth edition. New York: Oxford University Press, 2004.
- MALOBERTI, F. Analog Design for CMOS VLSI Systems. Boston: Kluwer Academic Publishers, 2001, p. 197-198.
- MANARESI, N., FRANCHI, E., GNUDI, A., BACCARANI, G. MOSFET threshold extraction circuit. Electronics Letters, 1995, vol. 31, no. 17, p. 1434-1435.
- CILINGIROGLU, U., HOON, S. K. An accurate self-bias threshold voltage extractor using differential difference feedback amplifier. In IEEE International Symposium on Circuits and Systems. Geneva (Switzerland), 2000, vol. 5, p. 209-212.

Keywords: CMOS, squarer circuit, rectifier, current-mode

**G. Koukiou , C. Psychalinos**
[references] [full-text]

Modular Filter Structures Using Current Feedback Operational Amplifiers

The concept of the wave filtering is followed in the derivation of high-order filter topologies by employing Current Feedback Operational Amplifiers as active blocks. For this purpose, the wave equivalent of an appropriate passive element chosen to be the elementary building block is introduced. As the wave equivalents of the other passive elements are derived by performing appropriate manipulations in the configuration of the wave equivalent of the elementary building block, an attractive characteristic offered by the derived filter topologies is the modularity of their structures. The validity of the proposed method is verified through experimental results in the case of a 3rd-order lowpass filter.

- PAYNE, A., TOUMAZOU, C. Analog amplifiers: classification and generalization. IEEE Transactions on Circuits and Systems-I: Fundamental Theory and Applications, 1996, vol. 43, no. 1, p. 43- 50.
- SOLIMAN, A. Applications of the current feedback amplifiers. Analog Integrated Circuits and Signal Processing, 1996, vol. 11, no. 3, p. 265-302.
- ISMAIL, A., SOLIMAN A. Novel CMOS current feedback op- amp realization suitable for high frequency applications. IEEE Transactions on Circuits and Systems-I: Fundamental Theory and Applications, 2000, vol. 47, no. 6, p. 918-921.
- HORNG, J. Voltage-mode multifunction filter using one current feedback amplifier and one follower. International Journal of Electronics, 2001, vol. 88, no. 2, p.153-157.
- PALUMBO, G., PENNISI S. Current feedback amplifier versus voltage operational amplifiers. IEEE Transactions on Circuits and Systems-I: Fundamental Theory and Applications, 2001, vol. 48, no. 5, p. 617-623.
- TAMMAM, A., KAYATLEH, K., LIDGEY, F. High CMRR current-feedback operational amplifier. International Journal of Electronics, 2003, vol. 90, no. 2. p. 87-97.
- SHARMA, R., SENANI, R. Multifunction CM/VM biquads realized with a single CFOA and grounded capacitors. International Journal of Electronics and Communications (AEU), 2003, vol. 57, no. 5, p. 301-308.
- SHARMA, R., SENANI, R. Universal current-mode biquad using a single CFOA. International Journal of Electronics, 2004, vol. 91, no. 3, p. 175-183.
- MAHMOUD, S., AWAD, I. Fully differential CMOS current feedback operational amplifier. Analog Integrated Circuits and Signal Processing, 2005, vol. 43, no. 1, p. 61-69.
- MITA, R., PALUMBO G., PENNISI, S. Low-voltage high-drive CMOS current feedback op-amp. IEEE Transactions on Circuits and Systems-II, 2005, vol. 52, no. 6, p. 317-321.
- SHAH, N., IQBAL, S., RATHER, M. Versatile voltage-mode CFA-based universal filter. International Journal of Electronics and Communications (AEU), 2005, vol. 59, no. 3, p.192-194.
- MAUNDY, B., SAKAR, A., GIFT, S. A new design topology for low-voltage CMOS current feedback amplifiers. IEEE Transactions on Circuits and Systems-II: Express Briefs, 2006, vol. 53, no. 1, p. 34-38.
- SINGH, V., SINGH, A., BHASKAR, D., SENANI, R. New universal biquads employing CFOAs. IEEE Transactions on Circuits and Systems- II, 2006, vol. 53, no. 11, p. 1299–1303.
- YUCE, E., MINAEI, S. A modified CFOA and its applications to simulated inductors, capacitance multipliers and analog filters. IEEE Transactions on Circuits and Systems-I, 2008, vol. 55, no. 1, p. 254-263.
- BIOLEK, D., SENANI, R., BIOLKOVA, V., KOLKA, Z. Active elements for analog signal processing: Classification, review, and new proposals. Radioengineering, 2008, vol. 17, no. 4, p. 15-32.
- RAIKOS, G., PSYCHALINOS, C. Low-voltage current feedback operational amplifiers. Circuits Systems and Signal Processing, 2009, vol. 28, no. 3, p. 377-388.
- TANGSRIRAT, W., SURAKAMPONTORN, W. Single- resistance-controlled quadrature oscillator and universal biquad filter using CFOAs. International Journal of Electronics and Communications (AEU), 2009, vol. 63, no. 12, p. 1080-1086.
- FABRE, A. Gyrator implementation from commercially available transimpedance operational amplifiers. Electronics Letters, 1992, vol. 28, no. 3, p. 263-264.
- WUPPER H., MEERKOTTER, K. New active filter synthesis based on scattering parameters. IEEE Transactions on Circuits and Systems, 1975, vol. 22, no. 7, p. 594-602.
- HARITANTIS, I., CONSTANTINIDES, A., DELIYANNIS, T. Wave active filters. IEE Proceedings, 1976, vol. 123, no. 7, p. 676-682.

Keywords: Current feedback operational amplifiers, continuous-time filters, wave active filters, analog signal processing.

**Y. Li**
[references] [full-text]

Electronically Tunable Current-Mode Quadrature Oscillator Using Single MCDTA

This paper presents a modified current differencing transconductance amlpifier (MCDTA) and the MCDTA based quadrature oscillator. The oscillator is current-mode and provides current output from high output impedance terminals. The circuit uses only one MCDTA and two grounded capacitors, and is easy to be integrated. Its oscillation frequency can be tuned electronically by tuning bias currents of MCDTA. Finally, frequency error is analyzed. The results of circuit simulations are in agreement with theory.

- BIOLEK, D., SENANI, R., BIOLKOVA, V., KOLKA, Z. Active elements for analog signal processing: classification, review, and new proposals. Radioengineeing, 2008, vol. 17, no. 4, p. 15 – 32.
- KESKIN, A. U., BIOLEK, D., HANCIOGLU, E., BIOLKOVA, V. Current-mode KHN filter employing current differencing trans- conductance amplifier. AEU – International Journal of Electronics and Communications, 2006, vol. 60, no. 6, p. 443 – 446.
- LI, Y. Forth order current mode band pass filter with coupled tuned by current using CCCDTAs. Journal of Electron Devices, 2010, vol. 7, p. 210 – 213.
- LAHIRI, A., CHOWDHURY, A. A novel first-order current-mode all-pass filter using CDTA. Radioengineeing, 2009, vol. 18, no. 3, p. 300 – 305.
- JAIKLA, W., SIRIPRUCHYANUN, M., BAJER, J., BIOLEK, D. A simple current-mode quadrature oscillator using single CDTA. Radioengineering, 2008, vol. 17, no. 4, p. 33 – 40.
- KESKIN, A. U., BIOLEK, D. Current mode quadrature oscillator using current differencing transconductance amplifiers (CDTA). IEE Proc.-Circuits Devices System, 2006, vol. 153, no. 3, p. 214 – 218.
- LAHIRI, A. Explicit-current-output quadrature oscillator using sec-ond-generation current conveyor transconductance amplifier. Radioengineeing, 2009, vol. 18, no. 4, p. 522 – 526.
- LAHIRI, A. Novel voltage/current-mode quadrature oscillator using current differencing transconductance amplifier. Analog Integrated Circuits and Signal Processing, 2009, Doi: 10.1007/s10470-009- 9291-0.
- LAHIRI, A. Resistor-less mixed-mode quadrature sinusoidal oscil- lator. International Journal of Computer and Electrical En- gineering, 2010, vol. 2, no. 1, p.63 – 66.
- LAHIRI, A. New current-mode quadrature oscillators using CDTA. IEICE Electronics Express, 2009, vol. 6, no. 3, p. 135 – 140.
- TANGSRIRAT, W., TANJAROEN, W. Current-mode sinusoidal quadrature oscillator with independent control of oscillation frequency and condition using CDTAs. Indian Journal of Pure & Applied Physics, 2010, vol. 48, no. 5, p. 363 – 366.
- SIRIPRUCHYANUN, M, JAIKLA, W., CMOS current-controlled current differencing transconductance amplifier and applications to analog signal processing. AEU-International Journal of Electronics and Communications, 2008, vol. 62, no. 4, p. 277 – 287.
- PRASAD, D., BHASKAR, D, R., SINGH, A, K. Realisation of Single-Resistance-Controlled Sinusoidal Oscillator: A new ap- plication of the CDTA. WSEAS Transactions on Electronics, 2008, vol. 5, no. 6, p. 257 – 259.
- TANGSRIRAT, W. Current differencing transconductance amplifier-based current-mode four-phase quadrature oscillator. Indian Journal of Engineering and Materials Sciences, 2007, vol. 14, no. 7, p. 289 – 294.
- TANGSRIRAT, W., TANJAROEN, W. Current-mode multiphase sinusoidal oscillator using current differencing transconductance amplifiers. Circuits, Systems and Signal Process, 2008, vol. 27, no. 1, p. 81 – 93.
- BIOLEK, D., HANCIOGLU, E., KESKIN, A, U. High- performance current differencing transconductance amplifier and its application in precision current-mode rectification AEU- International Journal of Electronics and Communication, 2008,vol 62, no. 2, p. 92 – 96.
- DUANGMALAI D, MANGKALAKEEREE S, SIRIPRU- CHYANUN M. High output-impedance current-mode quadrature oscillator using single MO-CCCDTA. In The seventh PSU Engineering Conference. Songkla (Thailand), 2009, p. 287 – 290.

Keywords: quadrature sinusoidal oscillator; current-mode circuit; Low-component-count ; MCDTA

**P. Kejik, S. Hanus, J. Blumenstein**
[references] [full-text]

Advanced Fuzzy Logic Based Admission Control for UMTS System

The capacity of CDMA (Code Division Multiple Access) systems is interference limited. Therefore radio resources management (RRM) functions are used. They are responsible for supplying optimum coverage, ensuring efficient use of physical resources, and providing the maximum planned capacity. This paper deals with admission control techniques for UMTS (Universal Mobile Telecommunication System). A UMTS system model and four fuzzy logic based admission control algorithms are presented in this paper. Two new versions of fuzzy logic based admission control algorithms are presented there. All algorithms are mutually compared via simulations. Simulations show that the novel advanced fuzzy algorithm outperforms the other simulated algorithms (in terms of blocking probability, dropping probability and the number of active UEs in cell).

- ROMERO, J., SALLENT, O., AGUSTI, R., DIAZ-GUERRA, M. Radio Resources Management Strategies in UMTS. New York: Wiley, 2005.
- AGUSTI, R., SALLENT, O., PEREZ, J., GORIA, P., MANGANI, N., VAILLANT, A. First Report on the Evaluation of RRM Algorithms by Simulation. [Online] 2002, Cited 2008-11-24. Available at: http://www.arrows-ist.upc.es/ .
- ELAYOUBI, S., CHAHED, T. Admission control in the downlink of WCDMA/UMTS. Wireless Systems and Mobility in Next Generation Internet. Lecture Notes in Computer Science, 2005, vol. 3427/2005, p. 136 – 151.
- LEVINE, D., AKYILDIZ, I., NAGHSHINEH, M. A resource estimation and call admission algorithm for wireless multimedia networks using the shadow cluster concept. In IEEE/ACM Transactions on Networking, 1997, vol. 5, no. 1.
- CAPONE, A., REDANA, S. I3E: A novel call admission control scheme for W-CDMA systems. Wireless Personal Communication, 2006, vol. 39, no. 1, p. 81 – 97.
- LIU, D., ZHANG, Y., HU, S. Call admission policies based on calculated power control setpoints in SIR-based power-controlled DS-CDMA cellular networks. Wireless Networks, July 2004, vol. 10, no. 4, p. 473 – 483.
- MALARKKAN, S., RAVICHANDRAN, V. Performance analysis of call admission control in WCDMA systems with adaptive multi class traffic based on fuzzy logic. In IJCSNS International Journal of Computer Science and Network Security, 2006, vol. 6, no. 11.
- CHANG, C.-J., KUO, L., CHEN, Y., SCHEN, S. Neural fuzzy call admission and rate controller for WCDMA cellular systems providing multirate services. In Proceedings of the 2006 International Conference on Wireless Communications and Mobile Computing. Vancouver (Canada), 2006, p. 383 – 388.
- KEJIK, P., HANUS, S. Fuzzy logic based call admission control in UMTS system. In CD: Proceedings of the 2009 1st International Conference on Wireless Communication, Vehicular Technology, Information Theory and Aerospace & Electronic System Technology. Aalborg (Denmark), 2009. p. 375 - 378.
- KEJIK, P., HANUS, S. Comparison of fuzzy logic and genetic algorithm based admission control strategies for UMTS system. Radioengineering, 2010, vol. 19, no. 1, p. 6 – 10.
- KEJIK, P., HANUS, S. Fuzzy logic based call admission control with user movement prediction for UMTS system. In Proceedings of the 20th International Conference Radioelektronika 2010. Brno (Czech Republic), 2010, p. 67 – 70.
- LO, J., BRITO, A., CORREIA, L., CORREIA, A. Simulation of call admission control, load control, handover and power control algorithms for enhanced UMTS. SEACORN Project [Online], Cited 2009-11-19. Available at http://seacorn.cs.ucy.ac.cy/- eumtssim/.
- KHOJA, J., AL-SHALASH, M., PRABHU, V. Dynamic system simulator for the modelling of CDMA systems. In Proceedings of the International Mobility and Wireless Access Workshop. Fort Worth (USA), 2002, p. 50 – 58.
- SOLDANI, D. QoS Management in UMTS Terrestrial Radio Access FDD Networks. Dissertation for the degree of Doctor of Science in Technology, Helsinki University of Technology, 2005.

Keywords: UMTS, CDMA, admission control, fuzzy logic

**Md. Masud Rana, J. Kim, W.-K. Cho**
[references] [full-text]

LMS Based Adaptive Channel Estimation for LTE Uplink

In this paper, a variable step size based least mean squares (LMS) channel estimation (CE) algorithm is presented for a single carrier frequency division multiple access(SC-FDMA) system under the umbrella of the long term evolution (LTE). This unbiased CE method can automatically adapts the weighting coefficients on the channel condition. Therefore, it does not require knowledge of channel,and noise statistics. Furthermore, it uses a phase weighting scheme to eliminate the signal fluctuations due to noise and decision errors. Such approaches can guarantee the convergence towards the true channel coefficient. The mean and mean square behaviors of the proposed CE algorithm are also analyzed. With the help of theoretical analysis and simulation results, we prove that the proposed algorithm outperforms the existing algorithms in terms of mean square error (MSE) and bit error rate (BER) by more than around 2.5dB.

- KARAKAYA, B., ARSLAN, H., CURPAN, H. A. An adaptive chan- nel interpolator based on Kalman ﬁlter for LTE uplink in high Doppler spread environments. EURASIP Journal on Wireless Com- mun. and Networking, 2009, Article ID 893751.
- BERKMANN, J., CARBONELLI, C., DIETRICH, F., DREWES, C., XU, W. On 3G LTE terminal implementation-standard, algo- rithms, complexities and challenges. In Proc. Wireless Communica- tions and Mobile Computing Conference. Crete (Greece), 2008, p. 970 – 975.
- ZHOU, M., JIANG, B., LI, T., ZHONG, W., GAO, X. DCT-based channel estimation techniques for LTE uplink. In Proc. Personal, In- door and Mobile Radio Communications. Tokyo (Japan), 2009.
- ANCORA, A., MEILI, C. B., SLOCK, D. T. Down-sampled impulse response least-squares channel estimation for LTE OFDMA. In Proc. International Conference on Acoustics, Speech, and Signal Process- ing. Honolulu (USA), 2007, p. III–293–III–296.
- MYUNG, H. G., LIM, J., GOODMAN, D. J. Peak to average power ratio for single carrier FDMA signals. In Proc. Personal, Indoor and Mobile Radio Communications. Helsinki (Finland), 2006, p. 1 – 5.
- SOHLAND, A., KLEIN, A. Block-IFDMA- iterative channel esti- mation versus estimation with interpolation ﬁlters. In Proc. Multi- Carrier Systems and Solutions. Herrsching (Germany), 2009, vol. 41, p. 123 – 132.
- PARK, S. Y., KIM, Y. G., KANG, C. G. Iterative receiver for joint detection and channel estimation in OFDM systems under mobile radio channels. IEEE Trans. on Vehicular Technology, 2004, vol. 53, no. 2, p. 450 – 460.
- HSIEH, M. H., WE, C. H. Channel estimation for OFDM systems based on comb-type pilot arrangement in frequency selective fading channels. IEEE Trans. on Consumer Electronics, 2004, vol. 44, no. 1, p. 217 – 225.
- DOUKOPOULOS, X. G., MOUSTAKIDES, G. V. Blind adaptive channel estimation in OFDM systems. IEEE Trans. on Wireless Com- munication, 2006, vol. 5, no. 7, pp. 1716 – 1725.
- ADIREDDY, S., TONG, L., VISWANATHAN, H. Optimal place- ment of training for frequency selective block fading channels. IEEE Trans. on Information Theory, 2002, vol. 48, no. 8, p. 2338 – 2353.
- KARAKAYA, B., ARSLAN, H., CURPAN, H. A. Channel estima- tion for LTE uplink in high Doppler spread. In Proc. Wireless Com- munications and Networking Conference. Las Vegas (USA), 2008, pp. 1126 – 1130.
- TEMINO, L. A. M. R. D., MANCHON, C. N. I., ROM, C., SøRENSEN, T. B., MOGENSEN, P. Iterative channel estimation with robust Wiener ﬁltering in LTE downlink. In Proc. Vehicular Technology Conference, Sept. 2008, p. 1 – 5.
- JIAN, W., YU, C., WANG, J., YU, J., WANG, L. OFDM adaptive digital predistortion method combines RLS and LMS algorithm. In Proc. Industrial Electronics and Applications. 2009, p. 3900 – 3903.
- YAPICI, Y., YILMAZ, A. O. Joint channel estimation and decoding with low-complexity iterative structures in time-varying fading chan- nels. In Proc. Personal, Indoor and Mobile Radio Communications, Tokyo (Japan), 2009, p. 1 – 5.
- CHO, H., LEE, C. W., KIM, S. W. Derivation of a new normalized least mean squares algorithm with modiﬁed minimization criterion. Signal Processing, 2009, vol. 89, no. 2, p. 692 – 695.
- COSTA, M. R. H., BERMUDEZ, J. C. M. A noise resilient variable step size LMS algorithm. Signal Processing, 2008, vol. 88, no. 3, p. 733 – 748.
- EVANS, J. B., XUE, P., LIU, B. Analysis and implementation of variable step size adaptive algorithms. IEEE Trans. on Signal Pro- cessing, 1993, vol. 41, p. 2517–2535.
- ZHAO, S., MAN, Z., KHOO, S., WU, H. R. Variable step size LMS algorithm with a quotient form. Signal Processing, 2009, vol. 89, no. 1, p. 67 – 76.
- MAYYAS, K., ABOULNASR, T. A robust variable step size LMS- type algorithm: analysis and simulations. In Proc. Acoustics, Speech, and Signal Processing. Detroit (USA), 1995, vol. 2, p. 1408 – 1411.
- KUN, Z., XIUBING, Z. A new modiﬁed robust variable step size LMS algorithm. In Proc. Industrial Electronics and Applications. 2009, p. 2699 – 2703.
- KWONG, R. H., JOHNSTON, E. W. A variable step size LMS al- gorithm. IEEE Trans. on Signal Processing, 1992, vol. 40, no. 7, p. 1633 – 1642.
- ABOULNASR, T., MAYYAS, K. A robust variable step size LMS- type algorithm: analysis and simulations. IEEE Trans. on Signal Pro- cessing, 1997, vol. 45, no. 3, p. 631 – 639.
- AKINO, T. K. Optimum-weighted RLS channel estimation for rapid fading MIMO channels. IEEE Trans. on Wireless Communication, 2008, vol. 7, no. 11, p. 4248 – 4260.
- ADACHI, F., TOMEBA, H., TAKEDA, K. Frequency-domain equal- ization for broadband single-carrier multiple access. IEICE Trans. Commun., 2009, vol. E92-B, no. 5, p. 1441 – 1456.
- YAMEOGO, S., PALICOT, J., CARIOU, L. Blind time domain equalization of SCFDMA signal. In Proc. Vehicular Technology Conference, Sept. 2009, p. 1 – 4.
- BEEK, J.-J. V. D., EDFORS, O., SANDELL, M. On channel estima- tion in OFDM systems. In Proc. Vehicular Technology Conference, Sept. 1995, vol. 2, p. 815 – 819.
- JAKES, W. C., Ed. Microwave Mobile Communications. New York: Wiley, 1994.
- KALAYCIOGLE, A., ILK, H. G. A robust threshold for itera- tive channel estimation in OFDM systems. Radioengineering, 2010, vol. 19, no. 1, p. 32 – 38.
- HAYKIN, S., Ed. Adaptive Filter Theory. 4th Ed. New Jersey: Pren- tice Hall, 1998.
- ZHANG, A., GONG, N. A novel variable step size LMS algorithm based on neural network. In Proc. International Conference on Intel- ligent Systems and Knowledge Engineering. 2007.
- BILGEKUL, H., DEREBOYLU, Z. Adaptive channel estimation of OFDM systems using the cyclic preﬁx with an RLS based algorithm in mobile channels. In Proc. of the IEEE 12th Signal Processing and Communication Applications Conference. Kusadasi (Turkey), 2004, p. 72 - 75.
- KARAMI, E., SHIVA, M. Decision-directed recursive least squares MIMO channels tracking. EURASIP Journal on Wireless Communi- cation and Networking, 2006, Article ID 43275.
- WAUTELET, X., HERZET, C., DEJONGHE, A., LOUVEAUX, J., VANDENDORPE, L. Comparison of EM-based algorithms for MIMO channel estimation. IEEE Transactions on Communication, 2007, vol. 55, no. 1, p. 216 – 226.
- SAYED, A. H. (Ed.) Fundamentals of Adaptive Filtering. New Jer- sey: John Wiley and Sons, 2003.

Keywords: SF-FDMA, PAPR, LMS, NLMS,VSS-LMS, RLS, LTE

**K. B. Baltzis**
[references] [full-text]

On the Effect of Channel Impairments on VANETs Performance

The primary means of studying the performance of vehicular ad hoc networks (VANETs) are computer simulations. Nowadays, the development of analytical models and the use of hybrid simulations that combine analytical modeling with discrete-event simulation are of great interest due to the significant reduction in computational cost. In this paper, we extend previous work in the area by suggesting an analytical model that includes distance-dependent losses, shadowing and small-scale fading. Closed-form expressions for the packet reception probability and the packet forwarding distance in the absence of simultaneous transmissions are presented. Numerical simulations validate the proposed formulation. The impact of path loss and fading on network throughput is explored. Interesting results that shows the efficacy of the approach are provided. The derived formulation is a useful tool for the modeling and analysis of vehicular communication systems.

- OLARIU, S., WEIGLE, M. C. Vehicular Networks: From Theory to Practice. Boca Raton: CRC Press, 2009.
- WIESER, V., PSENAK, V. Performance of advanced hybrid link adaptation algorithms in mobile radio channel. Radioengineering, 2008, vol. 17, no. 3, p. 81-86.
- KILLAT, M., SCHMIDT-EISENLOHR, F., HARTENSTEIN, H., ROSSEL, C., VORTISCH, P., ASSENMACHER, S., BUSCH, F. Enabling efficient and accurate large-scale simulations of VANETs for vehicular traffic management. In Proceedings of the 4th ACM International Workshop on Vehicular Ad Hoc Networks. Montreal (Canada), 2007, p. 29-38.
- CUOMO, F., MARTELLO, C., BAIOCCHI, A., CAPRIOTTI, F. Radio resource sharing for ad hoc networking with UWB. IEEE Journal on Selected Areas in Communications, 2002, vol. 20, no. 9, p. 1722-1732.
- KITANI, T., SHINKAWA, T., SHIBATA, N., YASUMOTO, K., ITO, M., HIGASHINO, T. Efficient VANET-based traffic information sharing system using buses on regular routes. In Proceedings of the 67th IEEE Vehicular Technology Conference. Singapore (Singapore), 2008, p. 3031-3036.
- KILLAT, M., HARTENSTEIN, H. An empirical model for probability of packet reception in vehicular ad hoc networks. EURASIP Journal on Wireless Communications and Networking, 2009, vol. 2009, article ID 721301, 12 pages. DOI:10.1155/2009/721301.
- RUBIO, L., REIG, J., CARDONA, N. Evaluation of Nakagami fading behaviour based on measurements in urban scenarios. AEU International Journal of Electronics and Communications, 2007, vol. 61, no. 2, p. 135–138.
- TALIWAL, V., JIANG, D., MANGOLD, H., CHEN, C., SENGUPTA, R. Empirical determination of channel characteristics for DSRC vehicle-to-vehicle communication. In Proceedings of the 1st ACM International Workshop on Vehicular Ad Hoc Networks. Philadelphia (USA), 2004, p. 88.
- SEYBOLD, J. S. Introduction to RF Propagation. Hoboken: Wiley, 2005.
- NEKOVEE, M. Modelling the spread of computer worms in vehicular ad hoc networks. In Proceedings of the 1st European Conference on Computer Network Defence. Glamorgan (UK), 2005, p. 115–124.
- SETIWAN, G., ISKANDER, S., CHEN, Q. J., KANHERE, S. S., LAN, K. C. The effect of radio models on vehicle network simulators. In Proceedings of the 14th World Congress on Intelligent Transport Systems. Beijing (China), 2007, p. 1-10.
- WOLNY, G. Modified DMAC clustering algorithm for VANETs. In Proceedings of the 3rd International Conference on Systems and Networks Communications. Sliema (Malta), 2008, p. 268-273.
- OKADA, H., TAKANO, A., MASE, K. A proposal of link metric for next-hop forwarding methods in vehicular ad hoc networks. In Proceedings of the 6th IEEE Consumer Communications and Networking Conference. Fredericton (Canada), 2009, p. 1-5.
- STOJMENOVIC, I., NAYAK, A., KURUVILA, J., OVALLE- MARTINEZ, F., VILLANUEVA-PENA, E. Physical layer impact on the design and performance of routing and broadcasting protocols in ad hoc and sensor networks. Computer Communications, 2005, vol. 28, no. 10, p. 1138–1151.
- XU, H., GARCIA-LUNA-ACEVES, J. J. Efficient broadcast for wireless ad hoc networks with a realistic physical layer. Ad Hoc Networks, 2010, vol. 8, no 2, p. 165-180.
- KUMAR, D., VENKATESH, R., KUMAR, A., ALTMAN E. Capacity optimizing hop distance in a mobile ad hoc network with power control. In Proceedings of the 4th International Symposium on Modeling and Optimization in Mobile, Ad Hoc and Wireless Networks. Boston (USA), 2006, p. 207-212.
- TORRENT-MORENO, M., SCHMIDT-EISENLOHR, F., FUBLER, H., HARTENSTEIN, H. Effects of realistic channel model on packet forwarding in vehicular ad hoc networks. In Proceedings of the 2006 IEEE Wireless Communications and Networking Conference. Las Vegas (USA), 2006, p. 385-391.
- BALTZIS, K. B. Closed-form description of microwave signal attenuation in cellular systems. Radioengineering, 2010, vol 19, no. 1, p. 11-16.
- BALTZIS, K. B. Analytical and closed-form expressions for the distribution of path loss in hexagonal cellular networks. Wireless Personal Communications, 2010, 12 pages. DOI: 10.1007/s11277- 010-9962-2.
- DOUSE, O., THIRAN, P. Connectivity vs capacity in dense ad hoc networks. In Proceedings of the 23rd Annual Joint Conference of the IEEE Computer and Communication Societies. Hong Kong (China), 2004, p. 476-486.
- SIMON, M. K., ALOUINI, M.-S. Digital Communication over Fading Channels. 2nd ed. Hoboken: John Wiley & Sons, Inc., 2005.
- ALOUINI, M.-S., GOLDSMITH, A. J. Area spectral efficiency of cellular mobile radio systems. IEEE Transactions on Vehicular Technology, 1999, vol. 48, no. 4, p. 1047–1066.
- GRADSHTEYN, I. S., RYZHIK, I. M. Table of Integrals, Series, and Products. 5th ed. London: Academic Press, 1994.
- JIANG, T., CHEN, H.-H., WU, H.-C., YI, Y. Channel modeling and inter-carrier interference analysis for V2V communication systems in frequency-dispersive channels. Mobile Networks and Applications, 2010, vol. 15, no. 1, p. 4-12.
- DENG, L.-Y., XU, H. A system of high-dimensional, efficient, long-cycle and portable uniform random generators. ACM Transactions on Modeling and Computer Simulation, 2003, vol. 13, no. 4, p. 299-309.
- RAESIDE, D. E. Monte Carlo principles and applications. Physics in Medicine and Biology, 1976, vol 21, no. 2, p. 181-197.
- ZHU, J., HUNG, K.-L., BENSAOU, B., NAIT-ABDESSELAM, F. Real-time tradeoff for reliable communication in wireless sensor networks. Computer Networks, 2008, vol. 52, no. 1, p. 25-43.
- KURUVILA, J., NAYAK, A., STOJMENOVIC, I. Hop count optimal position-based packet routing algorithms for ad hoc wireless networks with a realistic physical layer. IEEE Journal on Selected Areas in Communications, 2005, vol. 23, no. 6, p. 1267- 1275.

Keywords: VANET, packet reception, hop count, packet forwarding distance, composite fading channel, path loss.

**S. Mota, M. Outeiral Garcia, A. Rocha, F. Perez-Fontan**
[references] [full-text]

Estimation of the Radio Channel Parameters using the SAGE Algorithm

This paper presents the problem of estimating the parameters of a given number of superimposed signals, as is the case of the received signal in wireless communications. Based on the description of the received signal in the frequency domain, one version of the SAGE (Space-Alternating Generalized Expectation-Maximization) algorithm is presented, allowing the estimation, for each impinging ray, the delay, azimuth, elevation and complex amplitude. Ray retrieval results are presented in synthetic channels, using data generated with the extended Saleh Valenzuela (ESV) model, and also in real channels.

- SPENCER, Q. H., JEFFS, B. D., JENSEN, M. A., SWINDLEHURST, A. L. Modeling the statistical time and angle of arrival characteristics of an indoor multipath channel. IEEE Journal on Selected Areas in Communications, 2000, vol. 18, no. 3, p. 347 – 360.
- STEINBAUER, M., MOLISCH, A. F., BONEK, E. The double- directional radio channel. IEEE Antennas and Propagation Magazine, 2001, vol. 43, no. 4, p. 51 – 63.
- CHONG, C. C. et al. A new statistical wideband spatio- temporal channel model for 5-GHz band WLAN systems. IEEE Journal on Selected Areas in Communications, 2003, vol. 21, no. 2, p. 139 – 150.
- FESSLER, J. A., HERO, A. O. Space-alternating generalized expectation-maximization algorithm. IEEE Transactions on Signal Processing, 1994, vol. 42, no. 10, p. 2664 – 2677.
- FEDER, M., WEINSTEIN, E. Parameter-estimation of super- imposed signals using the EM algorithm. IEEE Transactions on Acoustics Speech and Signal Processing, 1988, vol. 36, no. 4, p. 477 – 489.
- FESSLER, J. A., HERO, A. O. Penalized maximum-likelihood image-reconstruction using space-alternating generalized EM algorithms. IEEE Transactions on Image Processing, 1995, vol. 4, no. 10, p. 1417 – 1429.
- CHUNG, P. J., BOHME, J. F. Comparative convergence analysis of EM and SAGE algorithms in DOA estimation. IEEE Transactions on Signal Processing, 2001, vol. 49, no. 12, p. 2940 – 2949.
- CHUNG, P. J., BOHME, J. F. Experimental study of the EM and SAGE algorithms with application to sonar data. In Sensor Array and Multichannel Signal Processing Workshop Proceedings. Rosslyn (USA), 2002, p. 77 – 81.
- FLEURY, B. H., TSCHUDIN, M., HEDDERGOTT, R., DAHLHAUS, D., PEDERSEN, K. I. Channel parameter estimation in mobile radio environments using the SAGE algorithm. IEEE Journal on Selected Areas in Communications, 1999, vol. 17, no. 3, p. 434 – 450.
- CHONG, C. C. et al. Joint detection-estimation of directional channel parameters using the 2-D frequency domain SAGE algorithm with serial interference cancellation. In ICC 2002, IEEE International Conference on Communications, vol. 2. New York (USA), 2002, p. 906 – 910.
- TSCHUDIN, M., HEDDERGOTT, R., TRUFFER, P. Vali- dation of a high resolution measurement technique for estimating the parameters of impinging waves in indoor environments. In Ninth IEEE International Symposium on Personal, Indoor and Mobile Radio Communications. Boston (USA), 1998, p. 1411 – 1416.
- MOTA, S., ROCHA, A. Parameter estimation of synthetic and real radio channels using the SAGE algorithm. In 13th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications Proceedings - Sailing the Waves of the Wireless Oceans. Lisboa (Portugal), 2002, p. 634 – 638.
- WALLACE, J. W., JENSEN, M. A. Modeling the indoor MIMO wireless channel. IEEE Transactions on Antennas and Propagation, 2002, vol. 50, no. 5, p. 591 – 599.
- WAX, M., KAILATH, T. Detection of signals by information theoretic criteria. IEEE Transactions on Acoustics Speech and Signal Processing, 1985, vol. 33, no. 2, p. 387 – 392.
- ZHANG, Q. T., WONG, K. M., YIP, P. C., REILLY, J. P. Statistical analysis of the performance of information theoretic criteria in the detection of the number of signals in array processing. IEEE Transactions on Acoustics, Speech and Signal Processing, 1989, vol. 37, no. 10, p. 1557 – 1567.
- FISHLER, E., GROSMANN, M., MESSER, H. Detection of signals by information theoretic criteria: general asymptotic performance analysis. IEEE Transactions on Signal Processing, 2002, vol. 50, no. 5, p. 1027 – 1036.
- NADLER, B. Nonparametric detection of signals by information theoretic criteria: performance analysis and an improved estimator. IEEE Transactions on Signal Processing, 2010, vol. 58, no. 5, p. 2746 – 2756.

Keywords: Parameter estimation, SAGE algorithm, radio channel measurements, multipath components

**L. Polak, T. Kratochvil**
[references] [full-text]

Simulation and Measurement of the Transmission Distortions of the Digital Television DVB-T/H Part 3: Transmission in Fading Channels

The paper deals with the third (and last) part of results of the Czech Science Foundation research project that was aimed into the simulation and measurement of the transmission distortions of the digital terrestrial television according to DVB-T/H standards. In this part the transmission of the digital television according to DVB-T/H standard over the fading channels and their models and profiles for fixed, portable and mobile reception is analyzed. Impact of the fading channels and their models on Modulation Error Rate from I/Q constellations and Bit Error Rates before and after Viterbi decoding in DVB-T/H signal decoding is presented.

- STUKAVEC, R., KRATOCHVIL, T. Simulation and measurement of the transmission distortions of the digital television DVB-T/H Part 1: Modulator for digital terrestrial television. Radioengineer- ing, 2010, vol. 19, no. 2, p. 338-346. ISSN: 1210-2512.
- STUKAVEC, R., KRATOCHVIL, T. Simulation and measurement of the transmission distortions of the digital television DVBT/H Part 2: Hierarchical modulation performance. Radioengineering, 2010, vol. 19, no. 3, p. 429-436. ISSN: 1210-2512.
- ETSI EN 300 744 V1.6.1 (2009-01). Digital Video Broadcasting (DVB), Framing Structure, Channel Coding and Modulation for Digital Terrestrial Television. European Standard ETSI, 2009.
- ETSI TR 101 290 V1.2.1 (2001-05). Technical report. Digital Video Broadcasting (DVB), Measurement Guidelines for DVB Systems. Technical Report ETSI, 2001.
- ETSI EN 302 304 V1.1.1 (2004-11). Digital Video Broadcasting (DVB), Transmission System for Handheld Terminals. European Standard ETSI, 2004.
- ETSI TR 102 377 V1.4.1 (2009-06). Digital Video Broadcasting (DVB), Implementation Guidelines for DVB Handheld Services. ETSI, 2009.
- FISHER, W. Digital Video and Audio Broadcasting. A Practical Engineering Guide. 2nd ed. Springer, 2008. ISBN 978-3-540- 76357-4.
- REIMERS, U. Digital Video Broadcasting, The Family of Interna- tional Standards for Digital Television. 2nd ed. Springer, 2004. ISBN 3-540-43545-X.
- KRATOCHVIL, T. DVB-T/H Laboratory transmission using fading channel profiles. In Proceedings of the 15th International Conference on Systems, Signals and Image Processing IWSSIP 2008. Bratislava: Slovak University of Technology, 2008, p. 343- 346. ISBN: 978-80-227-2856-0.
- KRATOCHVIL, T. DVB-T/H Portable and mobile TV performance in the new channel profiles modes. In Mehmood, R.; Cerqueira, E.; Piesiewicz, R.; Chlamtac, I. (Eds.): Communications Infrastructure, Systems and Applications., LNICST 160161, 2009. Lecture Notes of the Institute for Computer Sciences, Social- Informatics and Telecommunications Engineering (LNICST). London, UK: Springer, Institute for Computer Science, Social- Informatics and Telecommunications Engineering, 2009, p. 164- 173. ISBN: 978-3-642-11283-6.
- POLAK, L., KRATOCHVIL, T. Simulation of the DVB-H channel coding and transmission in MATLAB. In Proceedings of the 20th International Conference Radioelektronika 2010. Brno: Brno University of Technology, 2010, p. 57-60. ISBN: 978-1- 4244-6319-0.
- POLAK, L., KRATOCHVIL, T. Simulation of DVB- H transmission in Gaussian and fading channels. In Proceedings ELMAR-2010. Zadar (Croatia): ITG, Zagreb, 2010, p. 231-234. ISBN: 978-953-7044-11-4.

Keywords: Digital television, fading channel, fixed reception, portable reception, mobile reception, DVB-T/H

**M. R. Dincic, Z. H. Peric**
[references] [full-text]

Log-Polar Quantizer with the Embedded G.711 Codec

In this paper a new two-dimensional vector quantizer for memoryless Gaussian source, realized in polar coordinates, is proposed. The G.711 codec is embedded in our vector quantizer, and therefore our vector quantizer is compatible with the G.711 codec. It is simple for realization and it has much better performances, compared to the G.711 codec, such as much higher SQNR (signal-to-quantization noise ratio) for the same bit-rate, or bit-rate decrease for the same SQNR. The G.711 codec is widely used in many systems, especially in PSTN (public switched telephone network). Due to compatibility with the G.711 standard, our vector quantizer can be realized with simple software modification of the existing the G.711 codec, and therefore it can be very easily implemented in PSTN and other systems. So, small investments are needed for wide implementation of our model, but significant improvement of performances can be obtained.

- JAYANT, N. S., NOLL, P. Digital Coding of Waveforms. Prentice-Hall, 1984.
- ITU-T Recommendation G.711. Pulse code modulation (PCM) of voice frequencies, 1972.
- LYON, A. D. The μ-law CODEC. Journal of Object Technology, 2008, vol. 7, no. 8, p. 17-31.
- ITU-T Recommendation G.711.1. Wideband embedded extension for G.711 pulse code modulation, 2008.
- SASAKI, S., MORI, T., HIWASAKI, Y., OHMURO, H. Global standard for wideband speech coding: ITU-T G.711.1 (G.711 wideband extension). NTT Technical Review, vol. 6, no. 8, 2008.
- HIWASAKI, Y., MORI, T., SASAKI, S., OHMURO, H., KATAOKA, A. A wideband speech and audio coding candidate for ITU-T G.711 WBE standardization. In Proceeding of ICASSP2008. Las Vegas (Nevada, USA), 2008, p. 4017-4020.
- KOVESI, B., RAGOT, S., GUYADER, A. A 64-80-96 kbits/s scalable wideband speech coding candidate for ITU-T G.711-WB standardization. In Proceeding of ICASSP2008. Las Vegas (Nevada, USA), 2008, p. 4801-4804.
- HIWASAKI, Y., OHMURO, H., MORI, T., KURIHARA, S., KATAOKA, A. A G.711 embedded wideband speech coding for VoIP conferences. IEICE Trans. Inf. & Syst, 2006, vol. 89, no. 9, p. 2542-2552.
- PERIC, Z., DINCIC, M., DENIC, D., JOCIC, A. Forward adaptive logarithmic quantizer with new lossless coding method for Laplacian source. Wireless Personal Communications, 2010, published online, DOI: 10.1007/s11277-010-9929-3.
- PERIC, Z., STEFANOVIC, M. Asymptotic analysis of optimal uniform polar quantization. AEU - International Journal of Electronics and Communications, 2002, vol. 56, no. 5, p. 345-347.
- PERIC, Z., DINCIC, M., JOVANOVIC, A. Optimal log-polar image sampling. Journal of Communications Technology and Electronics, 2009, vol. 54, no. 12, p. 1397–1402.
- PERIC, Z., BOGOSAVLJEVIC, S. Asymptotic analysis of optimal piecewise uniform polar quantization. Radioengineering, vol. 13, no. 2, p. 26-30.
- ITU-T Recommendation G.712. Transmission performance characteristics of Pulse Code Modulation (PCM), 1992.
- MATSCHKAL, B., HUBER, J. B. Spherical logarithmic quantization. IEEE Transaction on Audio, Speech and Language Processing, 2010, vol. 18, no. 1, p. 126-140.
- RAVELLI, E., DAUDET, L. Embedded polar quantization. IEEE Signal Processing Letters, 2007, vol. 14, no. 10, p. 657-660.

Keywords: The G.711 standard, two-dimensional quantizer, polar coordinates, compatibility

**D.Brodic, Z. Milivojevic**
[references] [full-text]

Optimization of the Gaussian Kernel Extended by Binary Morphology for Text Line Segmentation

In this paper, an approach for text line segmentation by algorithm with the implementation of the Gaussian kernel is presented. As a result of algorithm, the growing area around text is exploited for text line segmentation. To improve text line segmentation process, isotropic Gaussian kernel is extended by dilatation. Furthermore, algorithms with isotropic and extended Gaussian kernels are examined and evaluated under different text samples. Results are given and comparative analysis is made for these algorithms. From the obtained results, optimization of the parameters defining extended Gaussian kernel dimension is proposed. The presented algorithm with the extended Gaussian kernel showed robustness for different types of text samples.

- AMIN, A., WU, S. Robust skew detection in mixed text/graphics documents. In Proceedings of the 8th ICDAR ’05. Seoul (Korea), 2005, p. 247 - 251.
- BASU, S., CHAUDHURI, C., KUNDU, M., NASIPURI, M., BASU, D. K. Text line extraction from multi-skewed handwritten document. Pattern Recognition, 2006, vol.40, p. 1825-1839.
- LIKFORMAN-SULEM, L., ZAHOUR, A., TACONET, B. Text line segmentation of historical documents: A Survey. International Journal on Document Analysis and Recognition, 2007, vol. 9, no. 2-4, p. 123-138.
- SILVA, L. F., CONCI, A., SANCHEZ, A. Automatic discrimination between printed and handwritten text in documents. In Proceedings of 22nd BSCGIP. Rio de Janeiro (Brazil), 2009, p. 261-267.
- BALLARD, D. H. Generalizing the Hough transform to detect arbitrary shapes. Pattern Recognition, 1981, vol. 13, no. 2, p. 111- 122.
- AMIN, A., FISCHER, A. A. Document skew detection method using the Hough transform. Pattern Analysis & Applications, 2000, vol. 3, no. 3, p. 243-253.
- SHI, Z., GOVINDARAJU, V. Line separation for complex document images using fuzzy runlength. In Proceedings of the IWDIAL ’04. Palo Alto (USA), 2004, p. 306-312.
- LIKFORMAN-SULEM, L., FAURE, C. Extracting lines on handwritten documents by perceptual grouping. In Advances in Handwriting and Drawing: a Multidisciplinary Approach, C. Faure, P. Keuss, G. Lorette, A. Winter (Eds), p. 21-38. Paris: Europia, 1994.
- ZAHOUR, A., TACONET, B., MERCY, P., RAMDANE, S. Arabic handwritten text-line extraction. In Proceedings of the 6th ICDAR ’01. Seattle (USA), 2001, p. 281-285.
- KOSHINAKA T., KEN'ICHI I., AKITOSHI O. An HMM-based Text Segmentation Method using Variational Bayes Approach. IEIC Technical Report 2004, pp.19-24, Vol.104, No.87, pp.19-24.
- LI, Y., ZHENG, Y., DOERMANN, D., JAEGER, S. A new algorithm for detecting text line in handwritten documents. In Proceedings of the 18th ICPR ’06. Hong Kong (China), 2006, vol. 2, p. 1030-1033.
- OTSU, N. A threshold selection method from gray-level histograms. IEEE Transactions on Systems, Man, and Cybernetics, 1979, vol. 9, no. 1, p. 62-66.
- GONZALES, R. C., WOODS, R. E. Digital Signal Processing, 2nd Ed. Upper Saddle River: Prentice-Hall, 2002, p. 116-118.
- BRODIC, D., MILIVOJEVIC, D. R., MILIVOJEVIC, Z. Basic test framework for the evaluation of text line segmentation and text parameter extraction. Sensors, 2010, vol. 10, no. 5, p. 5263-5279.
- BOLSTAD, W. M. Introduction to Bayesian Statistics. New York: John Wiley & Sons, 2004, p. 42-44.
- BRODIC, D., DOKIC, B. Initial skew rate detection using rectangular hull gravity center. In 14th International Conference on Electronics - E’2010. Vilnius (Lithuania), 2010, Sect.3.24, p. 1-6.

Keywords: OCR, document image processing, text line segmentation, Gaussian kernel, morphological operation.

**S. A. Chatzichristofis, A. Arampatzis, Y. S. Boutalis**
[references] [full-text]

Investigating the Behavior of Compact Composite Descriptors in Early Fusion, Late Fusion and Distributed Image Retrieval

In Content-Based Image Retrieval (CBIR) systems, the visual content of the images is mapped into a new space named the feature space. The features that are chosen must be discriminative and sufficient for the description of the objects. The key to attaining a successful retrieval system is to choose the right features that represent the images as unique as possible. A feature is a set of characteristics of the image, such as color, texture, and shape. In addition, a feature can be enriched with information about the spatial distribution of the characteristic that it describes. Evaluation of the performance of low-level features is usually done on homogenous benchmarking databases with a limited number of images. In real-world image retrieval systems, databases have a much larger scale and may be heterogeneous. This paper investigates the behavior of Compact Composite Descriptors (CCDs) on heterogeneous databases of a larger scale. Early and late fusion techniques are tested and their performance in distributed image retrieval is calculated. This study demonstrates that, even if it is not possible to overcome the semantic gap in image retrieval by feature similarity, it is still possible to increase the retrieval effectiveness.

- ARAMPATZIS, A., KAMPS, J. A signal-to-noise approach to score normalization. In Proceeding of the 18th ACM Conference on In- formation and Knowledge Management. Hong Kong (China), 2009, p. 797 – 806.
- ARAMPATZIS, A., ROBERTSON, S., KAMPS, J. Score distribu- tions in information retrieval. In Proceedings of the 2nd International Conference on Theory of Information Retrieval: Advances in Infor- mation Retrieval Theory. Cambridge (UK), 2009, p. 139 – 151.
- BERRETTI, S., DEL BIMBO, A., PALA, P. Merging results for distributed content based image retrieval. Multimedia Tools and Ap- plications, 2004, vol. 24, no. 3, p. 215 – 232.
- CHATZICHRISTOFIS, S., BOUTALIS, Y. FCTH: Fuzzy color and texture histogram-a low level feature for accurate image retrieval. In Proceedings of the 2008 Ninth International Workshop on Image Analysis for Multimedia Interactive Services WIAMIS’08. Klagenfurt (Austria), 2008, p. 191 – 196.
- CHATZICHRISTOFIS, S., BOUTALIS, Y. Content based radiology image retrieval using a fuzzy rule based scalable composite descrip- tor. Multimedia Tools and Applications, 2010, vol.46, no. 2-3, p. 493 – 519.
- CHATZICHRISTOFIS, S., BOUTALIS, Y., LUX, M. SPCD - spa- tial color distribution descriptor. a fuzzy rule based compact com- posite descriptor appropriate for hand drawn color sketches retrieval. In 2nd International Conference on Agents and Artiﬁcial Intelligence ICAART. Valencia (Spain), 2010, p. 58 – 63.
- CHATZICHRISTOFIS, S. A., BOUTALIS, Y. S., LUX, M. Selec- tion of the proper compact composite descriptor for improving con- tent based image retrieval. In Signal Processing, Pattern Recognition and Applications SPPRA 2009. Innsbruck (Austria), 2009, p. 134 – 140.
- CHATZICHRISTOFIS, S. A., BOUTALIS, Y. S., LUX, M. Img(rummager): An interactive content based image retrieval sys- tem. In Second International Workshop on Similarity Search and Applications SISAP 2009. Prague (Czech Republic), 2009, p. 151 – 153.
- CHATZICHRISTOFIS, S. A., ZAGORIS, K., BOUTALIS, Y. S., PAPAMARKOS, N. Accurate image retrieval based on compact composite descriptors and relevance feedback information. Inter- national Journal of Pattern Recognition and Artiﬁcial Intelligence (IJPRAI), 2010, vol. 24, no. 2, p. 207 – 244.
- CHATZICHRISTOFIS, S. A., BOUTALIS, Y. S. CEDD: Color and edge directivity descriptor: A compact descriptor for image indexing and retrieval. In6th International Conference on Computer Vision Systems ICVS 2008. Santorini (Greece), 2008.
- DATTA, R., JOSHI, D., LI, J., WANG, J. Image retrieval: Ideas, in- ﬂuences, and trends of the new age. ACM Computing Surveys, 2008, vol. 40, no. 2, p. 1 – 60.
- DESELAERS, T., KEYSERS, D., NEY, H. Features for image re- trieval: An experimental comparison. Information Retrieval, 2008, vol. 11, no. 2, p. 77 – 107.
- FRANK HSU, D., TAKSA, I. Comparing rank and score combina- tion methods for data fusion in information retrieval. Information Retrieval, 2005, vol. 8, no. 3, p. 449 – 480.
- FU, X., LI, Y., HARRISON, R., BELKASIM, S. Content-based im- age retrieval using gabor-zernike features. In 18th International Con- ference on Pattern Recognition. Hong Kong (China), 2006, vol. 2.
- GUSTAFSON, D., KESSEL, W. Fuzzy clustering with a fuzzy co- variance matrix. In 1978 IEEE Conference on Decision and Control including the 17th Symposium on Adaptive Processes. 1978, vol. 17., p. 761 – 766.
- HAWKING, D., ROBERTSON, S. On collection size and retrieval effectiveness. Information Retrieval, 2003, vol. 6, no. 1, p. 99 – 105.
- JARRAH, K., GUAN, L. Content-based image retrieval via dis- tributed databases. InInternational conference on Content-based im- age and video retrieval. Niagara Falls (Canada), 2008, p. 389 – 394.
- JOVIC, M., HATAKEYAMA, Y., DONG, F., HIROTA, K. Image re- trieval based on similarity score fusion from feature similarity rank- ing lists. Lecture Notes in Computer Science, 2006, vol. 4223, p. 461 – 470.
- KAMPS, J., DE RIJKE, M., SIGURBJORNSSON, B. Combination methods for crosslingual web retrieval. Lecture Notes in Computer Science, 2006, vol. 4022, p. 856 – 864.
- LEE, I., GUAN, L. Semi-automated relevance feedback for dis- tributed content based image retrieval. In International Conference on Multimedia and Expo ICME 2004. Taipei (Taiwan), 2004, vol. 3., p. 1871 – 1874.
- LUX, M., CHATZICHRISTOFIS, S. Lire: lucene image retrieval: an extensible java cbir library. In Proceedings of the 16th International Conference on Multimedia. Vancouver (Canada), 2008.
- M. BLESCHKE , R. MADONSKI, R. RUDNICKI. Image retrieval system based on combined mpeg-7 texture and colour descriptors. In 16th International Conference Mixed Design of Integrated Circuits and Systems MIXDES 2009. Lodz (Poland), 2009, p. 635 – 639.
- MANJUNATH, B., OHM, J., VASUDEVAN, V., YAMADA, A. Color and texture descriptors. IEEE Transactions on Circuits and Systems for Video Technology, 2001, vol. 11, no. 6, p. 703 – 715. 1
- MANJUNATH, B., SALEMBIER, P., SIKORA, T. Introduction to MPEG-7: Multimedia Content Description Interface. New York: Wiley, 2002.
- MPEG-7. Subjective Evaluation of the MPEG-7 Retrieval Accuracy Measure (ANMRR). ISO/WG11, Doc. M6029, 2000.
- NG, C., SIA, K., CHANG, C. Advanced peer clustering and ﬁrework query model in the peer-to-peer network. In 12th International World Wide Web Conference (WWW). Budapest (Hungary), 2003.
- NISTER, D., STEWENIUS, H. Scalable recognition with a vocabu- lary tree. In 2006 IEEE Computer Society Conference on Computer Vision and Pattern Recognition. 2006, vol. 5, p. 2161 – 2168.
- SCHAEFER, G., STICH, M. Ucid-an uncompressed colour image database. Storage and Retrieval Methods and Applications for Mul- timedia, 2004, vol. 5307, p. 472 – 480.
- SMEULDERS, A., WORRING, M., SANTINI, S., GUPTA, A., JAIN, R. Content-based image retrieval at the end of the early years. IEEE Transactions on Pattern Analysis and Machine Intelligence, 2000, vol. 22, no. 12, p. 1349 – 1380.
- SPYROU, E., LE BORGNE, H., MAILIS, T., COOKE, E., AVRITHIS, Y., O CONNOR, N. Fusing mpeg-7 visual descriptors for image classiﬁcation. Lecture Notes in Computer Science, 2005, vol. 3697, p. 847 – 852.
- TAMURA, H., MORI, S., YAMAWAKI, T. Textural features corre- sponding to visual perception. IEEE Transactions on Systems, Man and Cybernetics, 1978, vol. 8, no. 6, p. 460 – 473.
- WANG, J., LI, J., WIEDERHOLD, G. Simplicity: Semantics- sensitive integrated matching for picture libraries. IEEE Transac- tions on Pattern Analysis and Machine Intelligence, 2001, vol. 23, no. 9, p. 947–963.
- WON, C., PARK, D., PARK, S. Efﬁcient use of mpeg-7 edge his- togram descriptor. Etri Journal, 2002, vol. 24, no. 1, p. 23 – 30.
- WONG, K., CHEUNG, K., PO, L. Mirror: an interactive content based image retrieval system. In IEEE International Symposium on Circuits and Systems ISCAS 2005. Kobe (Japan), 2005, vol. 2, p. 1541 – 1544.

Keywords: CBIR, Compact Composite Descriptors, Early Fusion, Late Fusion, Distributed Image Retrieval.

**F. A. Mianji, Y. Zhang, A. Babakhani**
[references] [full-text]

Key Information Retrieval in Hyperspectral Imagery through Spatial-Spectral Data Fusion

Hyperspectral (HS) imaging is measuring the radiance of materials within each pixel area at a large number of contiguous spectral wavelength bands. The key spatial information such as small targets and border lines are hard to be precisely detected from HS data due to the technological constraints. Therefore, the need for image processing techniques is an important field of research in HS remote sensing. A novel semisupervised spatial-spectral data fusion method for resolution enhancement of HS images through maximizing the spatial correlation of the endmembers (signature of pure or purest materials in the scene) using a superresolution mapping (SRM) technique is proposed in this paper. The method adopts a linear mixture model and a fully constrained least squares spectral unmixing algorithm to obtain the endmember abundances (fractional images) of HS images. Then, the extracted endmember distribution maps are fused with the spatial information using a spatial-spectral correlation maximizing model and a learning-based SRM technique to exploit the subpixel level data. The obtained results validate the reliability of the technique for key information retrieval. The proposed method is very efficient and is low in terms of computational cost which makes it favorable for real-time applications.

- MANOLAKIS, D., MARDEN, D., SHAW, D. A. Hyperspectral image processing for automatic target detection applications. Lincoln Laboratory Journal, 2003, vol. 14, no.1, p. 79-116.
- BUTTINGSRUD, B., ALSBERG, B. K. Superresolution of hyperspectral images. Chemometrics and Intelligent Laboratory Systems, 2006.
- MIANJI, F. A., ZHANG, Y., SULEHRIA, H. K., BABAKHANI, A., KARDAN, M. R. Superresolution challenges in hyperspectral imagery. Information Technology Journal, 2008, vol. 7, no. 7, p. 1030-1036.
- MIANJI, F. A., ZHANG, Y., BABAKHANI, A. Optimum method selection for resolution enhancement of hyperspectral imagery. Information Technology Journal, 2009, vol. 8, no. 3, p. 263-274.
- JANE, O., ILK, G. A quantitative study on optimum parameters selection in adaptive unsharp masking technique for infrared images. Radioengineering, 2009, vol. 18, no. 4, p. 611-617.
- AKGUN, T., ALTUNBASAK, Y., MERSEREAU, R. M. Super- resolution reconstruction of hyperspectral images. IEEE Trans. Image Process., 2005, vol. 14, no. 11, p. 1860-1875.
- MARIA, M. T., NUNEZ, J. Super-resolution of remotely sensed images with variable-pixel linear reconstruction. IEEE Trans. Geosci. Remote Sens., 2007, vol. 45, no. 5, p. 1446–1457.
- HARDIE, R. C., EISMANN, M. T. MAP estimation for hyper- spectral image resolution enhancement using an auxiliary sensor. IEEE Trans. Image. Process., 2004, vol. 13, no. 9, p. 1174–1184.
- ROBINSON, G. D., GROSS, H. N., SCHOTT, J. R. Evaluation of two applications of spectral mixing models to image fusion. Remote Sensing of Environment, 2000, vol. 71, no. 3, p. 272–281.
- EISMANN, M. T., HARDIE, R. C. Hyperspectral resolution enhancement using high-resolution multispectral imagery with arbitrary response functions. IEEE Trans. Geosci. Remote. Sens., 2005, vol. 43, no. 3, p. 455–465.
- GROSS, H. N., SCHOTT, J. R. Application of spectral mixture analysis and image fusion techniques for image sharpening. Remote Sensing of Environment, 1998, vol. 63, no. 2, p. 85–94.
- EISMANN, M. T., HARDIE, R. C. Application of the stochastic mixing model to hyperspectral resolution enhancement. IEEE Trans. Geosci. Remote. Sens., 2004, vol. 42, no.9, p. 1924–1933.
- ATKINSON, P. M., CULTER, M. E. J., LEWIS, H. Mapping sub- pixel proportional land cover with AVHRR imagery, Int. J. Remote Sens., 1997, vol. 18, no. 4, p. 917–935.
- WINTER, M. E., WINTER, E. M. Physics-based resolution enhancement of hyperspectral data. In Proceedings of SPIE, 2002, no. 4725, p. 580–587.
- CHEN, F., Using spectral-shape parameters to improve linear spectral mixture analysis. Int. J. Remote Sens., 2009, vol. 30, no. 22, p. 6061-6067.
- BROWN, M., GUNN, S. R., LEWIS, H. G. Support vector machines for optimal classification and spectral unmixing. Ecol. Model., 1999, vol. 120, no. 2, p. 167–179.
- FORERO, S. V., MANIAN, V. Improving hyperspectral image classification using spatial preprocessing. IEEE Geosci. Remote Sens. Lett., 2009, vol. 6, no. 2, p. 297-301.
- TARABALKA, Y., BENEDIKTSSON, J. A., CHANUSSOT, J. Spectral-spatial classification of hyperspectral imagery based on partitional clustering techniques. IEEE Trans. Geosci. Remote Sens., 2009, vol. 47, no. 8, p. 2973-2987.
- FOODY, G. M. Sharpening fuzzy classification output to refine the representation of sub-pixel land cover distribution. Int. J. Remote Sens., 1998, vol. 19, no. 13, p. 2593–2599.
- DOBIGEON, N., TOURNERET, J. Y., CHANG, C. I. Semi- supervised linear spectral unmixing using a hierarchical Bayesian model for hyperspectral imagery. IEEE Trans. Remote Sens. Geosci., Jul. 2008, vol. 56, no. 7, p. 2684-2695.
- NGUYEN, M. Q., ATKINSON, P. M., LEWIS, H. G. Superresolution mapping using a Hopfield neural network with fused images. IEEE Trans. Geosci. Remote Sens., 2006, vol. 44, no. 3, p. 736–749.
- TATEM, A. J., LEWIS, H. G., ATKINSON, P. M., NIXON, M. S. Superresolution target identification from remotely sensed images using a Hopfield neural network. IEEE Trans. Geosci. Remote Sens., 2001, vol. 39, no. 4, p. 781–796.
- MERTENS, K. C., VERBEKE, L. P. C., WESTRA, T., DE WULF, R. R. Subpixel mapping and subpixel sharpening using neural network predicted wavelet coefficients. Remote Sens. Environ., 2004, vol. 91, no. 2, p. 225–236.
- GU, Y., ZHANG, Y., ZHANG, J. Integration of spatial-spectral information for resolution enhancement in hyperspectral images. IEEE Trans. Geosci. Remote Sens., 2008, vol. 46, no. 5, p. 1347- 1358.
- GE, Y., LI, S., LAKHAN, V. C. Development and testing of a subpixel mapping algorithm. IEEE Trans. Signal Process. 2009, vol. 47, no. 7, p. 2155-2164.
- WINTER, M. E. N-Finder: An algorithm for fast autonomous spectral end-member determination in hyperspectral data. In Proceedings of SPIE, 1999, vol. 3753, p. 266–275.
- BOARDMAN, J. W., KRUSE, F. A., GREEN, R. O. Mapping target signatures via partial unmixing of AVIRIS data. In Summaries of the VI JPL Airborne Earth Science Workshop. Pasadena (CA), 1995.
- BATESON, C. A., CURTISS, B. A method for manual endmember selection and spectral unmixing. Remote Sens. Environ., 1996, vol. 55, p. 229–243.
- IFARRAGUERRI, A., CHANG, C.-I. Multispectral and hyperspectral image analysis with convex cones. IEEE Trans. Geosci. Remote Sens., 1999, vol. 37, p. 756–770.
- NEVILLE, R. A., STAENZ, K., SZEREDI, T., LEFEBVRE, J., HAUFF, P. Automatic endmember extraction from hyperspectral data for mineral exploration. In Proceedings of the 21st Can. Symp. Remote Sensing, Ottawa, ON, Canada, 1999.
- BOWELS, J., PALMADESSO, P. J., ANTONIADES, J. A., BAUMBACK, M. M., RICKARD, L. J. Use of filter vectors in hyperspectral data analysis. In Proceedings SPIE, 1995, vol. 2553, p. 148–157.
- BATESON, C. A., ASNER, G. P., WESSMAN, C. A. Endmember bundles: A new approach to incorporating endmember variability into spectral mixture analysis. IEEE Trans. Geosci. Remote Sens., 2000, vol. 38, p. 1083–1094.
- PLAZA, A., MARTINEZ, P., PEREZ, R., PLAZA, J. Spatial/spectral endmember extraction by multidimensional morphological operations. IEEE Trans. Geosci. Remote Sens., 2002, vol. 40, no. 9, p. 2025–2041.
- PLAZA, A., MARTINEZ, P., PEREZ, R., PLAZA, J. A Quantitative and comparative analysis of endmember extraction algorithms from hyperspectral data. IEEE Trans. Geosci. Remote Sens., 2004, vol. 42, no. 3, p. 650-663.
- WANG, J., CHANG, C.-I. Applications of independent component analysis in endmember extraction and abundance quantification for hyperspectral imagery. IEEE Trans. Geosci. Remote Sens., 2006, vol. 44, no. 9, p. 2601–2616.
- GOORDIN, D. G., GAO, J., HENERBRY, G. M. The effect of solar illumination angle and sensor view angle on observed patterns of spatial structure in tall grass prairie. IEEE Trans. Geosci. Remote Sens., 2004, vol. 42, no. 1, p. 154-165.
- SANDMEIER, S. R., MIDDLETON, E. M., DEERING, D. W., QIN, W. The potential of hyperspectral bidirectional reflectance distribution function data for grass canopy characterization. Journal of Geophysical Research, 1999, vol. 104, no. D8, p. 9547– 9560.
- BOLTON, J., GADER, P. Random set framework for context- based classification with hyperspectral imagery. IEEE Trans. Geosci. Remote Sens., Nov. 2009, vol. 47, no. 11, pp. 3810–3821.
- DAS, S. K., SINGH, R. Performance of kriging-based soft classification on wiFS-IRS-1D image using ground hyperspectral signatures. IEEE Geosci. Remote Sens. Lett., Jul. 2009, vol. 6, no. 3, pp. 453–457.
- PENN, B. S. Using simulated annealing to obtain optimal linear end-member mixtures of hyperspectral data. Computers & Geosciences, 2002, vol. 28, p. 809–817.
- BACHMANN, C. M., AINSWORTH, T. L., FUSIANA, R. A. Exploiting manifold geometry in hyperspectral imagery. IEEE Trans. Geosci. Remote Sens., 2005, vol. 43, no. 3, p. 441-454.
- ADAMS, J. B., SMITH, M. O. Spectral mixture modeling: A new analysis of rock and soil types at the Viking Lander 1 suite. Journal of Geophysical Research, 1986, vol. 91, p. 8098-8112.
- BOARDMAN, J. W. Inversion of imaging spectrometry data using singular value decomposition. In Proceedings of IEEE Symposium of Geoscience and Remote Sensing (IGARSS), 1989, p. 2069-2072.
- HEINZ, D., CHANG, C.-I. Fully constrained least squares linear spectral mixture analysis method for material quantification in hyperspectral imagery. IEEE Trans. Geosci. Remote Sens., 2001, vol. 39, no. 3, p. 529–545.
- BROADWATER, J., CHELLAPPA, R. Hybrid detectors for subpixel targets. IEEE Trans. on Pattern Analysis and Machine Intelligence, 2007, vol. 29, no. 11, p. 1891–1903.
- RICHARDS, J. A., JIA, X. Using suitable neighbors to augment the training set in hyperspectral maximum likelihood classification. IEEE Geosci. Remote Sens. Lett., Oct. 2008, vol. 5, no. 4, p. 774– 777.
- RUMELHART, D. E., McCLELLAND, J. L. Parallel Distributed Processing. Cambridge, MA: MIT Press, Jul. 1987.
- HORNIK, K., STINCHCOMBE, M., WHITE, H. Multilayer feedforward networks are universal approximators. Neural Networks, 1989, vol. 2, no. 5, p. 359–366.
- IRIE, B., MIYAKE, S. Capabilities of three-layered perceptrons. In Proceedings of the Int. Joint Conf. Neural Netw., 1988, vol. 3, p. 1641–1648.
- GREEN, R.O., EASTWOOD, M. L., SARTURE, C. M., CHRIEN, T. G., ARONSSON, M., CHIPPENDALE, B. J., FAUST, J. A., PAVRI, B. E., CHOVIT, C. J., SOLIS, M., OLAH, M. R., WILLIAMS, O. Imaging spectroscopy and the airborne visible/infrared imaging spectrometer (AVIRIS). Remote Sens. Environ., 1998, vol. 65, pp. 227–248.

Keywords: Key information retrieval, hyperspectral imagery, material radiance, spectral unmixing, superresolution