Extended orthogonal space-time block coded transmission with quantised differential feedback

Extended orthogonal space-time coding can use feedback of channel state information to increase the diversity gain of the transmission. This paper calculates the maximum attainable gain, and shows the effect that quantisation in the feedback channel has on the system performance. We demonstrate that for slow-fading channels, differential coding with a single feedback bit can achieve near-optimum performance and exceed the performance of non-differential feedback with higher word length. We also comment on combining differential encoding with channel estimation. Simulation results compare this approach to state-of-the-art systems with standard quantised and unquantised feedback.