Genetically enhanced TTCM assisted MMSE multi-user detection for SDMA-OFDM

Abstract

In this contribution a GA-aided MMSE MUD is proposed for employment in a TTCM-assisted SDMA-OFDM system, which is capable of achieving a similar performance to that attained by its MLD-aided counterpart at a significantly lower complexity, especially at high user loads.

Multiuser MIMO-OFDM for Next-Generation Wireless Systems

“…This will catastrophically degrade the performance of numerous known detection approaches, such as for example the Vertical Bell Labs Layered SpaceTime architecture (V-BLAST) [10], [120], [278] detector of [146], the LS/MMSE algorithms of [1], [268] and the QR Decomposition combined with the M-algorithm (QRD-M) algorithm of [184]. However, with the aid of the recently proposed GA-aided MUDs [279]- [284], this problem can be efficiently solved. We will further discuss this issue in Section IV.…”

“…Its employment in Rayleigh fading channels was considered by Yen et al in [25], [316], and [317] in diverse scenarios, both with and without the aid of diversity techniques, respectively. However, apart from the transceiver research conducted in the context of CDMA systems [25], [318]- [321], GAs have not been exploited to their full potential in wireless communication systems until recently, when they were also applied to STBC-aided MUD scenarios [322], beamforming MIMO detection problems [323] and SDMA-based MIMO OFDM systems [56], [279]- [284], [324]. These promising GA-aided applications are summarized at a glance in Table 10.…”

“…Since there is a total of P number of receiver antennas, the combined OF can be formulated as [279], [280] ð sÞ…”

“…The GAs can be combined with the MMSE MUD for the sake of contriving a more powerful concatenated MMSE-GA MUD [279], [280], which is capable of achieving a similar performance to that attained by the optimum ML MUD at a significantly lower computational complexity, especially at high user loads. The schematic of a concatenated MMSE-GA MUD aided multiuser SDMA-OFDM system is given in Fig.…”

“…In the concatenated MMSE-GA MUD [279], [280], the GA's optimization process exploits the symbol estimates generated by the MMSE MUD as initial information. More specifically, the MMSE-based estimated signal vectorŝ MMSE 2 C LÂ1 is obtained by linearly combining the signals received by the P different receiver antenna elements with the aid of the MMSE array weight matrix, as follows [1] …”