A MIMO-OFDM maximum likelihood reception scheme in cochannel interference environments

The paper proposes a new multiple-input multiple-output (MIMO)-OFDM receiver that is based on maximum likelihood (ML) estimation under rich cochannel interference conditions. The proposed receiver consists of several branch metric generators and an ML detector using metrics that the generators output. In the branch metric generator, a whitening matched filter suppresses interference by combining received signals linearly. An FFT transforms the filter's outputs into subcarrier signals. Subtracting replica signals from the subcarrier signals and squaring the result yield the metrics. Coefficients of the whitening matched filters and channel impulse responses, that are necessary for generating the replica signals, are simultaneously estimated by the eigenvalue-decomposition of an autocorrelation matrix of the received signals and known preambles. To reduce the computational complexity, a simplified version that possesses only one branch metric generator and that estimates its parameters by the RLS algorithm is also proposed. Computer simulations under the interference-limited condition demonstrate that the proposed receivers are much superior to the conventional ML-based one in BER performance.