Effect of low-resolution ADCs and loop interference on multi-user full-duplex massive MIMO amplify-and-forward relaying systems

This paper focuses on a multi-user full-duplex massive multiple-input multiple-output amplify-and-forward relaying system with low-resolution analogue-to-digital convertors (ADCs). By modelling the loop-interference and quantisation noise as additive noise, we perform the analyses of the achievable spectral efficiency (SE) by considering the two canonical processing schemes, maximum ratio combining/maximal ratio transmission (MRC/MRT) and zero-forcing receive/zero-forcing transmission (ZFR/ZFT), respectively. Specially, we first obtain the tractable closed-form expressions of the achievable SE. Then, we present the asymptotic analyses under three different power-scaling scenarios. Comparison analysis shows that the low-resolution quantisers impose more performance loss on ZFR/ZFT schemes than MRC/MRT ones. At the same time, it is found that with different power-scaling schemes, the systems have different capabilities to restrict the effect of loop interference and low-resolution ADCs. Specially, the impact of both the loop-interference and quantisers on achievable SE can be restricted effectively only under the power-scaling scenario where the relay's transmission power is scaled down with the number of transmit antennas and the sources' transmission power is fixed. For the power-scaling case where the transmission powers of both relay and sources are scaled down simultaneously with the number of antennas, only the effect of the loop interference can be restricted, but the one of low-resolution quantisers remains.