A decision-feedback equalizer with selective time-reversal operation for high-rate indoor radio communication

The author discusses the use of a receiver with a time-reversal structure for improving the performance of a low-complexity decision-feedback equalizer (DFE) in slowly fading dispersive indoor radio environments. Time-reversal operation is done by storing each block of received signal samples in a buffer and reversing the sequential order of the signal samples in time prior to equalization. As a result, the equivalent channel impulse response as seen by the DFE becomes a time reverse of the actual channel impulse response. The author describes useful performance bounds for such a receiver and studies important topics, including optimum symbol and burst timing recovery, and the combined use of equalization and diversity reception. Simulation results for a proposed receiver implementation that incorporates the time-reversal concept are presented. It is shown that a DFE with a very short forward filter can be effectively used to eliminate the effects of multipath time dispersion up to several symbols in duration