A novel multicarrier CDMA transmission scheme for cognitive radios with sidelobe suppression

SUMMARY Noncontiguous multicarrier code division multiple access (MC-CDMA) is an effective multiple access method for cognitive radio systems that can deploy the noncontiguous vacant parts of a certain spectrum shared with the users of a primary system. However, the large spectral sidelobes of the Fourier transform based implementation of the MC-CDMA interfere with the adjacent primary transmission. In this paper, a novel complex signature sequence set is proposed for synchronous downlink MC-CDMA based cognitive radio networks to suppress the sidelobes. To do so, the minimization of the sidelobes power is developed as an eigen-optimization problem that is optimally solved by using the eigenvalue decomposition method. The optimal complex signature sequences are chosen as the eigenvectors attained by the eigenvalue decomposition of a symmetric matrix that is dependent of the spectral characteristics of the primary users. Simulation results show that by a slight decrease in the maximum number of active users compared with full load, the sidelobes can be considerably suppressed. The effect of cyclic prefix length, the bandwidth of the primary system and the number of active users on the sidelobe suppression performance is analyzed through numerical simulations. Copyright © 2012 John Wiley & Sons, Ltd.

[1]  Said Esmail El-Khamy,et al.  Performance evaluation of OFDM and single-carrier systems using frequency domain equalization and phase modulation , 2011, Int. J. Commun. Syst..

[2]  B. Parlett.  The Symmetric Eigenvalue Problem , 1981 .

[3]  Hüseyin Arslan,et al.  OFDM for cognitive radio: merits and challenges , 2009, IEEE Wireless Communications.

[4]  Athanasios V. Vasilakos,et al.  Novel overlay/underlay cognitive radio waveforms using SD-SMSE framework to enhance spectrum efficiency- part i: theoretical framework and analysis in AWGN channel , 2009, IEEE Transactions on Communications.

[5]  Zhou Yuan,et al.  On Sidelobe Suppression for Multicarrier-Based Transmission in Dynamic Spectrum Access Networks , 2010, IEEE Transactions on Vehicular Technology.

[6]  F.K. Jondral,et al.  Mutual interference in OFDM-based spectrum pooling systems , 2004, 2004 IEEE 59th Vehicular Technology Conference. VTC 2004-Spring (IEEE Cat. No.04CH37514).

[7]  Yong-Hwan Lee,et al.  Cooperative spectrum sensing with imperfect feedback channel in the cognitive radio systems , 2010, Int. J. Commun. Syst..

[8]  Char-Dir Chung,et al.  Asymptotic spectral behavior of spectrally precoded OFDM signal with arbitrary input statistics , 2009, IEEE Communications Letters.

[9]  See-May Phoong,et al.  OFDM transmitters: analog representation and DFT-based implementation , 2003, IEEE Trans. Signal Process..

[10]  Richard A. Johnson,et al.  Applied Multivariate Statistical Analysis , 1983 .

[11]  Behrouz Farhang-Boroujeny,et al.  Multicarrier communication techniques for spectrum sensing and communication in cognitive radios , 2008, IEEE Communications Magazine.

[12]  E-L. Kuan,et al.  Overview of Multicarrier CDMA , 2004 .

[13]  Ming Chen,et al.  A precoding scheme for DFT-based OFDM to suppress sidelobes , 2009, IEEE Communications Letters.

[14]  Jaap van de Beek.  Sculpting the multicarrier spectrum: a novel projection precoder , 2009, IEEE Communications Letters.

[15]  Robert H. Halstead,et al.  Matrix Computations , 2011, Encyclopedia of Parallel Computing.

[16]  Neal Patwari,et al.  Filterbank Multicarrier and Multicarrier CDMA for Cognitive Radio Systems , 2007, 2007 2nd International Conference on Cognitive Radio Oriented Wireless Networks and Communications.

[17]  Kyunbyoung Ko,et al.  Effects of carrier frequency offset on the average effective SNR and the average BER for asynchronous MC-CDMA uplink systems with a guard period , 2011, Int. J. Commun. Syst..

[18]  Vincent K. N. Lau,et al.  Joint Cross-Layer Scheduling and Spectrum Sensing for OFDMA Cognitive Radio Systems , 2009, 2009 IEEE Wireless Communications and Networking Conference.

[19]  Shih-Gu Huang,et al.  Improvement of active interference cancellation: avoidance technique for OFDM cognitive radio , 2009, IEEE Transactions on Wireless Communications.

[20]  Hüseyin Arslan,et al.  Sidelobe suppression in OFDM-based spectrum sharing systems using adaptive symbol transition , 2008, IEEE Communications Letters.

[21]  Michele Luglio.  Guest Editor's Introduction: Mobile Multimedia Satellite Communications , 1999, IEEE Multim..

[22]  Friedrich Jondral,et al.  Spectrum pooling: an innovative strategy for the enhancement of spectrum efficiency , 2004, IEEE Communications Magazine.

[23]  Joseph Mitola.  Cognitive Radio for Flexible Mobile Multimedia Communications , 2001, Mob. Networks Appl..

[24]  Michael Schnell,et al.  Reduction of out-of-band radiation in OFDM systems by insertion of cancellation carriers , 2006, IEEE Communications Letters.

[25]  Morteza Rajabzadeh,et al.  Receiver design for downlink MIMO MC-CDMA in cognitive radio systems , 2010, 21st Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications.

[26]  Michael Schnell,et al.  Subcarrier weighting: a method for sidelobe suppression in OFDM systems , 2006, IEEE Communications Letters.

[27]  Tao Jiang,et al.  Extended Active Interference Cancellation for Sidelobe Suppression in Cognitive Radio OFDM Systems With Cyclic Prefix , 2010, IEEE Transactions on Vehicular Technology.

[28]  Lang Hong,et al.  Performance Evaluation of Adaptive Non-contiguous MC-CDMA and Non-contiguous CI/MC-CDMA for Dynamic Spectrum Access , 2008, 2008 3rd International Conference on Cognitive Radio Oriented Wireless Networks and Communications (CrownCom 2008).

[29]  Ha H. Nguyen,et al.  Resource Allocation for OFDMA-Based Cognitive Radio Multicast Networks With Primary User Activity Consideration , 2010, IEEE Transactions on Vehicular Technology.

[30]  Hamid Aghvami,et al.  Cognitive Radio Transmission Based on Direct Sequence MC-CDMA , 2008, IEEE Transactions on Wireless Communications.

[31]  Linda Doyle,et al.  Exploring the Reconfigurability Options of Multi-Carrier CDMA in Cognitive Radio Systems , 2007, 2007 IEEE 18th International Symposium on Personal, Indoor and Mobile Radio Communications.

[32]  H. Arslan,et al.  Spectrum shaping of OFDM-based cognitive radio signals , 2008, 2008 IEEE Radio and Wireless Symposium.