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Differential space-time ultra-wideband communications

In this paper, we present two space-time schemes for exploiting diversity in multi-antenna impulse radio ultra wide-band (IR-UWB) systems when neither the transmitter nor the receiver has access to channel state information. The first scheme encodes the pulses of the same data symbol by a combination of differential phase shift keying and permutation codes and can be associated with any number of transmit and receive antennas. The second scheme encodes different symbols with two transmit antennas. These schemes are associated with Rake receivers and achieve full spatial and multi-path diversity with no data rate loss for constant-modulus multi-dimensional constellations. Adaptive versions of these schemes are also presented and shown to approach the performance of coherent receivers in stationary indoor channels.