Title: Performance of 16-state TCM MC-CDMA with various SUD techniques over downlink wireless channels

Authors: Osama M. Hussain; Imran A. Tasadduq

Addresses: Communication & Information Research Center (CIRC), Sultan Qaboos University (SQU), Al-Khoudh, PC-123, P.O. Box 50, Muscat, Oman ' Department of Computer Engineering, College of Computer & Information Systems, Umm Al-Qura University, P.O. Box 715, Makkah 21955, Saudi Arabia

Abstract: We present a novel combination of 16-state 8-phase shift keying/8-quadrature amplitude modulation (8-QAM) trellis coding schemes with multicarrier code division multiple access (MC-CDMA) and various single user detection (SUD) techniques. In literature, it is well established that minimum mean square error (MMSE) is the optimum SUD technique when used with fully loaded uncoded MC-CDMA systems. We show that for fully loaded systems, 8-QAM trellis-coded MC-CDMA equalised with threshold orthogonality restoring combining (TORC) outperforms equivalent systems that use MMSE by almost 1.4 dB at a bit error rate of 10^-5. Conversely, it is known that single user loaded uncoded MC-CDMA equalised with maximum ratio combining provides best performance among all SUD methods. We report that among all possible combinations of the underlying trellis-coded modulation, MC-CDMA and SUD techniques, TORC equalised 8-QAM trellis-coded MC-CDMA systems provide the best performance as they do for fully loaded systems. Hence, this combination appears to be a promising candidate for both downlink and uplink channels.

Keywords: MC-CDMA; multicarrier CDMA; code division multiple access; MAI; multiple access interference; Rayleigh fading channels; SUD; single user detection; TORC; threshold orthogonality restoring combining; TCM; trellis-coded modulation.

DOI: 10.1504/IJAACS.2013.052894

International Journal of Autonomous and Adaptive Communications Systems, 2013 Vol.6 No.2, pp.149 - 166

Accepted: 24 May 2011
Published online: 13 Sep 2014 *

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