Adaptive TORC detection for MC-CDMA wireless systems

Multi carrier code-division multiple access (MC-CDMA) is considered for beyond third generation wireless systems for its effectiveness in the presence of both multipath fading and interference. This paper analyzes MC-CDMA systems adopting an adaptive detection technique based on threshold orthogonality restoring combining (TORC). The mathematical framework here developed allows the evaluation of both the bit error probability and the bit error outage in downlink with perfect and imperfect channel state information and the derivation of the TORC threshold that optimizes the performance. The optimal threshold is analytically derived as a function of the number of subcarriers, the number of active users, and the mean signal-to-noise ratio. This enables an adaptive variation of the threshold following slow processes fluctuations. Numerical results show very good performance of TORC with optimal threshold comparing with others combining techniques with perfect and imperfect channel estimation. Results are shown both in uncorrelated Rayleigh fading as well as in time and frequency correlated fading channels.

[1]  Jean-Paul M. G. Linnartz,et al.  Controlled equalization of multi-carrier CDMA in an indoor Rician fading channel , 1994, Proceedings of IEEE Vehicular Technology Conference (VTC).

[2]  Moe Z. Win,et al.  Bit error outage for diversity reception in shadowing environment , 2003, IEEE Communications Letters.

[3]  Moe Z. Win,et al.  MRC performance for M-ary modulation in arbitrarily correlated Nakagami fading channels , 2000, IEEE Communications Letters.

[4]  Ramjee Prasad,et al.  An overview of multi-carrier CDMA , 1996, Proceedings of ISSSTA'95 International Symposium on Spread Spectrum Techniques and Applications.

[5]  Moe Z. Win,et al.  Virtual branch analysis of symbol error probability for hybrid selection/maximal-ratio combining in Rayleigh fading , 2001, IEEE Trans. Commun..

[6]  Moe Z. Win,et al.  Antenna subset diversity with non-ideal channel estimation , 2008, IEEE Transactions on Wireless Communications.

[7]  Khaled Fazel,et al.  Multi-Carrier and Spread Spectrum Systems , 2003 .

[8]  Moe Z. Win,et al.  On the inverse symbol-error probability for diversity reception , 2003, IEEE Trans. Commun..

[9]  Jean-Paul M. G. Linnartz,et al.  Multi-Carrier Cdma In Indoor Wireless Radio Networks , 1994 .

[10]  John G. Proakis,et al.  Performance of the multi-stage detector for a MC-CDMA system in a Rayleigh fading channel , 1996, Proceedings of GLOBECOM'96. 1996 IEEE Global Telecommunications Conference.

[11]  Mohamed-Slim Alouini,et al.  Digital Communication over Fading Channels: Simon/Digital Communications 2e , 2004 .

[12]  H. Rohling,et al.  Comparison of different detection algorithms for OFDM-CDMA in broadband Rayleigh fading , 1995, 1995 IEEE 45th Vehicular Technology Conference. Countdown to the Wireless Twenty-First Century.

[13]  Milica Stojanovic,et al.  Performance of adaptive MC-CDMA detectors in rapidly fading Rayleigh channels , 2003, IEEE Trans. Wirel. Commun..

[14]  K. V. S. Hari,et al.  IEEE 802.16 Broadband Wireless Access Working Group Title Channel Models for Fixed Wireless Applications (final IEEE 802.16 TG3 ad hoc version) Date Submitted , 2001 .

[15]  N. Yee,et al.  BER of multi-carrier CDMA in an indoor Rician fading channel , 1993, Proceedings of 27th Asilomar Conference on Signals, Systems and Computers.

[16]  S. Kaiser.  On the performance of different detection techniques for OFDM-CDMA in fading channels , 1995, Proceedings of GLOBECOM '95.

[17]  Michael Schnell,et al.  Combined equalization for uplink MC-CDMA in Rayleigh fading channels , 2005, IEEE Transactions on Communications.

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

[19]  Andrea Conti,et al.  How Equalization Techniques Affect the TCP Performance of MC-CDMA Systems in Correlated Fading Channels , 2008, EURASIP J. Wirel. Commun. Netw..

[20]  Luca Sanguinetti,et al.  Channel estimation for MC-CDMA uplink transmissions with combined equalization , 2006, IEEE Journal on Selected Areas in Communications.

[21]  Moe Z. Win,et al.  Slow Adaptive $M$ -QAM With Diversity in Fast Fading and Shadowing , 2007, IEEE Transactions on Communications.

[22]  Andrea Conti,et al.  On the down-link performance of multi-carrier CDMA systems with partial equalization , 2007, IEEE Transactions on Wireless Communications.

[23]  Roberto Verdone,et al.  Millimeter waves for short-range multimedia communication systems , 1998, Proc. IEEE.

[24]  Ramjee Prasad,et al.  Overview of multicarrier CDMA , 1997, IEEE Commun. Mag..

[25]  K. Fazel,et al.  Multi-Carrier and Spread Spectrum Systems: Fazel/Spread Spectrum , 2004 .

[26]  S. Ben Slimane.  Partial equalization of multi-carrier CDMA in frequency selective fading channels , 2000, 2000 IEEE International Conference on Communications. ICC 2000. Global Convergence Through Communications. Conference Record.

[27]  Stefan Kaiser,et al.  A Unified Analysis of Diversity Exploitation in Multicarrier CDMA , 2007, IEEE Transactions on Vehicular Technology.

[28]  Vinko Erceg,et al.  Channel Models for Fixed Wireless Applications , 2001 .

[29]  L.J. Greenstein,et al.  An empirically-based path loss model for wireless channels in suburban environments , 1998, IEEE GLOBECOM 1998 (Cat. NO. 98CH36250).