Relaying for massive MIMO

Multi-user massive MIMO relaying is a cost-effective, pragmatic solution to one of the fundamental bottlenecks of the wireless physical layer, namely, the low-area spectral efficiency. Specifically, a combination of massive MIMO and wireless relaying techniques can potentially be exploited for improving the trade-off between spectral efficiency and coverage, thereby substantially improving the achievable area spectral efficiency. To this end, in this chapter, system configurations, transmission frame structures, CSI acquisition techniques and signal processing aspects for multi-user massive MIMO relay networks have been presented. Moreover, the corresponding channel models and favourable propagation conditions have been reviewed, and thereby, a generalized end-to-end signal model has been developed. First, the performance analysis techniques and the underlying mathematical tools have been presented, and then, they have been used for deriving basic performance metrics including asymptotic SINR and achievable sum rate expressions. Finally, important insights have been drawn by using these performance metrics, and thereby, the validity and viability of the proposed system, channel and signal models can be ascertained.