Iterative Multi-User Detection for OFDM Using Biased Mutation Assisted Genetic Algorithms

Space Division Multiple Access (SDMA) aided Oralso been employed in OFDM systems [7, 8] for achieving a nearthogonal Frequency Division Multiplexing (OFDM) systems assisted optimum performance. Against this background, the novel contriby efficient Multi-User Detection (MUD) techniques have recently bution of this paper is that we propose a MMSE-assisted Iteraattracted intensive research interests. As expected, Maximum Liketive GA (IGA) MUD invoking a technique referred to here as the lihood (ML) detection was found to attain the best performance, Biased Q-function Based Mutation (BQM) designed for improvalthough this was achieved at the cost of a high computational coming the performance of a TTCM-aided multi-user SDMA-OFDM plexity. Forward Error Correction (FEC) schemes such as Turbo system. Our simulation results show that the proposed MMSETrellis Coded Modulation (TTCM) can be efficiently amalgamated IGA assisted TTCM-SDMA-OFDM system is capable of achievwith SDMA-OFDM systems for the sake of improving the achieving an Eb/No gain of about 6dB in comparison to the TTCMable performance without bandwidth expansion. In this contriassisted MMSE-SDMA-OFDM benchmarker system both in lowbution, a MMSE-aided Iterative GA (IGA) MUD is proposed for and high-throughput modem scenarios, such as 4QAM and 16QAM, employment in a TTCM-assisted SDMA-OFDM system, which is respectively, while maintaining a substantially lower complexity capable of achieving a similar performance to that attained by its than that imposed by the optimum ML MUD. optimum ML-aided counterpart at a significantly lower complexThe structure of this paper is as follows. The SDMA MIMO chanity, especially at high user loads. Moreover, when the proposed nel model is described in Section 2.1, while the overview of the pronovel Biased Q-function Based Mutation (BQM) scheme is emposed TTCM-aided SDMA-OFDM system using the MMSE-IGAMUD ployed, the IGA-aided system's performance can be further imis given in Section 2.2, followed by the introduction of the novel BQM proved by achieving an Eb/No gain of about 6dB in comparison scheme of Section 3. Our simulation results are provided in Section 4, to the TTCM-aided MMSE-SDMA-OFDM benchmarker system while Section 5 concludes our findings. both in lowand high-throughput modem scenarios, respectively, while still maintaining a modest complexity. 2. SYSTEM MODEL