Robust adaptive detection in linearly precoded MIMO-OFDM systems with hard/soft decoding

Maximum likelihood detection (MLD) has been shown to offer large performance gains within the context of linearly precoded MIMO-OFDM systems with multiple-stream transmission when compared to an all-linear setup (i.e., linear transmitter/receiver), although at the cost of a higher computational complexity. To overcome this handicap, this paper proposes a method to selectively choose the detection strategy (ML or linear) as a function of the instantaneous channel conditions and the accuracy of the channel state information at the transmitter (CSIT). The proposed technique is suitable for both hard- and soft-decoded setups. Numerical results show that a cautious and selective use of ML detection substantially reduces complexity while still reaping most of the performance advantage.