Comparison of linear and MLSE spatio-temporal interference rejection combining with an antenna array in a GSM system

By using multiple receiving antennas and spatial or spatio-temporal processing techniques cochannel interference (CCI) may be suppressed. The maximum likelihood (ML) estimator requires a spatio-temporal model of the CCI. The model may be inaccurate because of estimation errors or difficulties in the parametrization of the generally asynchronous CCI. In this case linear spatio-temporal filtering based on training or semi-blind algorithms can be competitive compared to the ML-based algorithms. This paper compares the performance of ML and linear spatio-temporal techniques in synchronous and asynchronous interference-limited GSM urban scenarios. The best results for the asynchronous CCI and/or propagation channels with fading are obtained with a linear spatio-temporal semi-blind filtering technique based on minimization of the dual least squares constant modulus criterion.