Double differential space-time block coding for time-selective fading channels

Most existing space-time coding schemes assume time-invariant fading channe ls and offer antenna diversity gains relying on accurate channel estimates at the receiver. Recent single differential space-time block coding schemes forego channel estimation but are less effective in rapidly fading environ ments. Based on a diagonal unitary matrix group, a novel double differentia l space-time block coding approach is derived in this paper for time-select ive fading channels. Without estimating the channels at the receiver, infor mation symbols are recovered with antenna diversity gains regardless of fre quency offsets. The resulting transceiver has very low complexity and is ap plicable to an arbitrary number of transmit and receive antennas. Approxima tely optimal space-time codes are also designed to minimize bit error rate. System performance is evaluated both analytically and with simulations.