Maximum likelihood detection of co-channel communication signals exploiting the spatio-temporal diversity

With an antenna array, we can exploit the spatio-temporal diversity of digital wireless communications to increase the channel capacity. Signal (waveform) estimation in most array processing algorithms is based on the so-called signal copy concept. The basic idea behind signal copy is to estimate each signal waveform by simply nulling out other co-channel signals based on their spatio-temporal diversity. Then detection of each signal is done independently based on each waveform estimate. Clearly, this method is suboptimal, since it solves the optimization problem in two stages instead of solving the problem jointly. In this paper we present a maximum-likelihood signal detection (MLSD) algorithm that detects multiple co-channel signals jointly in the presence of multipath fading. The MLSD is implemented using the Viterbi algorithm (VA). While the MLSD need a little more computation complexity than the signal copy methods, its performance gain is very significant.