Cochannel interference cancellation within the current GSM standard

The performance of Maximum Likelihood Sequence Estimation (MLSE) is bounded (and often approximated well) by the Matched Filter Bound (MFB). In this paper, we first show how the GMSK modulation of GSM can be linearized and reformulated to have a real symbol constellation, leading to a two-channel aspect due to the in-phase and in-quadrature components of the received signal. More channels can be added by oversampling and/or the use of multiple antennas. We present the MFB for this model in the presence of colored noise (interferers) for MLSE that employs noise correlation information that in general may differ from the true one. Simulation results show that significant interference cancellation is possible, even with one antenna, if the correlation structure of the interference is taken into account properly in the MLSE.