Subspace method for separating cochannel TDMA signals

In this paper, we describe an adaptive algorithm that uses a subspace method for separating cochannel time-division multiple-access (TDMA) signals impinging on an antenna array. A frame synchronization algorithm is initially employed to identify the cochannel scenario. The adaptive algorithm uses a subspace decomposition of the array signals to constrain the beamformer weights for the signal of interest to be in a specific subspace. This subspace corresponds to the orthogonal complement of the subspace spanned by the direction vectors of the interferers. A follow-on linear equalizer removes the intersymbol interference (ISI) introduced by the transmit filter.