Detection of multiuser TCM MC-CDMA with TORC over downlink Rayleigh fading channels

In this letter, a combination of 16-state 8-QAM trellis codes with multi-carrier code division multiple access (MC-CDMA) and threshold orthogonality restoring combining (TORC) is introduced over downlink Rayleigh fading channels. In literature, minimum mean square error (MMSE) when applied with MC-CDMA is considered to be the optimum single user detection (SUD) technique. We show that the proposed system, in both full and single user load, outperforms an equivalent system that uses MMSE at BER of 10-5 by almost 1.35 and 1.27 dB, respectively. Moreover, as number of active users increase, error performance of proposed system surpasses that with MMSE which suggests its superior robustness to multiple access interference (MAI).