Max-min Analog Beamforming for High Altitude Platforms Communication Systems

Abstract

This paper considers a Multi-User Multiple Input Multiple Output (MU-MIMO) communication scenario, which is based on high altitude platforms (HAPs) equipped with a large scale antenna array. Traditional digital beamformers require plenty of RF chains so that large power consumption is inevitable. Moreover, sophisticated amplitude-phase design of digital beamforming in baseband will lead to high computational complexity. Therefore, we propose a max-min analog beamforming algorithm named as Epigraph-Relax-Bisection-Decomposition (ERBD) for HAP-based MU-MIMO communication systems, which achieves less power consumption compared to digital ones. The scheme uses a semi-definite relaxation (SDR) approach to approximate the quadratically constraint quadratic programming (QCQP) beamforming problem. Simulation results show that the proposed ERBD algorithm outperforms the traditional analog beamforming algorithms. ERBD is suitable for power consumption limited HAP-based communication systems.