Energy-Efficient Resource Allocation for Massive MIMO Amplify-and-Forward Relay Systems

Energy-efficient resource allocation is investigated for multi-pair massive MIMO amplify-and-forward relay systems, where a dedicated relay assists pairwise information exchange among many pieces of single-antenna user equipment (UE). The system energy efficiency (EE) is theoretically analyzed by employing large system analysis and random matrix theory. This analytical result provides excellent approximation for the system with a moderate number of antennas, and it also enables several efficient algorithms, working with a different knowledge of channel state information (CSI), to maximize the system EE by scheduling the optimal numbers of relay antennas and UE pairs as well as the corresponding relay transmission power. In contrast to the conventional resource allocation schemes, the proposed algorithms avoid complicated matrix calculations and the instantaneous CSI of small-scale fading; therefore, they are computationally efficient with low CSI overhead. The proposed optimization framework sheds light on the optimized system configurations, and it also offers an efficient way to achieve EE-oriented resource allocation for the multi-pair massive MIMO relay systems.