Low-feedback adaptive-rate mimo spatial multiplexing with zero forcing detection

Abstract

In this paper, a rate-adaptive spatial multiplexing system with zero-forcing (ZF) detection is proposed for spatiallywhite MIMO Rayleigh fading channels, feeding back only constellation selection information, which has the advantage of low feedback compared to classical approaches. We evaluate the spectral efficiency achieved by rate adaptation according to the received SNR and we compare the achieved rates with that of the non-adaptive case and with the Shannon capacity. It is shown that the proposed rate-adaptive spatial multiplexing MIMO system achieves a significant gain in spectral efficiency compared to its non-adaptive counterpart in the SNR region of practical interest. An evaluation of the effect of feedback delay on the performance is also undertaken. It is observed that since an increasing diversity order mitigates the effect of fading and makes the channel behave more similarly to an AWGN channel, it also mitigates the effect of delay.