A robust adaptive MIMO eigenmode transmission system with ZF beamspace interference canceller

In this paper, we propose an adaptive MIMO EMTS with a beamspace zero forcing (ZF) interference canceller in Rx and a single channel encoder for all eigenmodes. Generalized BER equations for various constellations applicable for all quality of CSI at Tx are also derived. Each eigenmode is modeled as an AWGN channel, to a Nakagami-Rice fading channel and lastly to a Rayleigh fading channel as the CSI at Tx degrades from perfect to partial and to no CSI. Thus our proposed system provides a smooth transition between the different qualities of CSI and encompasses the perfect, partial and no CSI paradigms with the generalized BER equations. With this smooth transition, it is possible to trade feedback frequency (or overhead) with throughput performance according to the system design and channel conditions. Our proposed system is therefore a robust and practical scheme that has the potential for implementation.