Space-time processing techniques for detection and copy of co-channel signals

In this paper we apply jointly optimized space-time processing techniques to detect and copy signals in the presence of co-channel interferers. In particular, we treat the "overloaded" case where the number of interferers equals or exceeds the number of antennas. The detection technique combines beamsteering (spatial) with multirate subband processing (temporal) to construct the power-frequency-angle datagram (PFAgram). The copy technique is based on a jointly optimized MMSE analysis. The results are shown to include the spatial-only and temporal-only solutions as special cases. The jointly optimized approach affords a multiplicative enhancement in performance due to the exploitation of cross terms in the joint covariance matrix. One feature of this approach is that the PFAgram constructed for detection contains the necessary information to calculate the copy solution. Examples are presented that show successful detection and copy under overloaded conditions.