Differential spatial multiplexing

In this paper, we present a novel differential space-time (DST) architecture which is well suited for high data-rate applications but requires only a linear decoding complexity. Multiple transmit antennas are divided into groups and DST encoding is applied individually to each group. Instead of using the optimum joint-group decoding approach, the proposed receiver combines group interference suppression (GIS) and decision-feedback differential detection (DF-DD) to reduce the decoding complexity. By taking advantage of the differential encoding at the transmitter, the GIS filters can be calculated without explicit knowledge of channel state information. Since the optimization of the GIS filters requires a generalized eigendecomposition of two correlation matrices, we also devise efficient adaptive algorithms for recursive filter optimization. It is shown that both the GIS filter computation and the detection scheme are robust against carrier phase variations