Minimum error rate beamforming transceivers

Iterative multiuser receivers constitute an effective solution for transmission over Multiple Access Interference (MAI) infested channels, when invoking a com- bined Multiuser Detector (MUD) and channel decoder. Most reduced-complexity methods in this area use the Minimum Mean Squared Error (MMSE) MUD. Since the desired output of Binary Phase Shift Keying (BPSK) modulated sys- tems is real-valued, minimising the Mean Squared Error, (MSE) between the beamformer's desired output and the real part of the beamformer output has the potential of significantly improving the attainable Bit Error Rate (BER) per- formance. We refer to this MMSE design as the Real-valued Minimum Mean Squared Error (RMMSE) receiver. In this thesis, we explore a new Soft-Input Soft-Output (SISO) Interference Cancellation (IC) aided multiuser detection al- gorithm based on the novel Minimum Bit Error Rate (MBER) criterion. We demonstrate that the MBER turbo receiver outperforms both the MMSE and the RMMSE algorithms, particularly in so-called rank-deficient beamforming sys- tems, where the number of receiver antennas is-lower than the number of users supported. A novel iterative Soft Interference Cancellation (SIC) aided beam- forming receiver is also developed for high-throughput Quadrature Amplitude Modulation (QAM) assisted systems. The proposed SIC based Minimum Symbol Error Rate (MSER) multiuser detection scheme guarantees the direct and explicit minimisation of the Symbol Error Rate (SER) at the output of the detector. This thesis also studies the Mutual Information (MI) transfer characteristics of the proposed iterative SIC aided beamforming receiver communicating over both Additive White Gaussian Noise (AWGN) and slow-fading channels. Based on the Extrinsic Information Transfer (EXIT) chart technique, we investigate