Massive MIMO Asymptotics for Ray-Based Propagation Channels

• Published in: IEEE transactions on wireless communications Vol. 19; no. 6; pp. 3977 - 3991
• Main Authors: Li, Shuang, Smith, Peter J., Dmochowski, Pawel A., Tataria, Harsh, Matthaiou, Michail, Yin, Jingwei
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.06.2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Antenna arrays; Antenna measurements; Antennas; Asymptotic methods; Asymptotic properties; Cellular structure; Channel hardening; Channel models; Channels; Communication Systems; Electrical Engineering, Electronic Engineering, Information Engineering; Elektroteknik och elektronik; Engineering and Technology; favorable propagation; Hardening; Interference; Kommunikationssystem; Linear antenna arrays; Linear arrays; Massive MIMO; MIMO (control systems); Propagation; ray-based; Teknik; ULA; UPA; Wireless communication
• ISSN: 1536-1276; 1558-2248
• DOI: 10.1109/TWC.2020.2979146

Favorable propagation (FP) and channel hardening (CH) are desired properties in massive multiple-input multiple-output (MIMO) systems. To date, these properties have primarily been analyzed for classical statistical channel models, or ray-based models with very specific angular parameters and distributions. This paper presents a thorough mathematical analysis of the asymptotic system behavior for ray-based channels with arbitrary ray distributions, and considers two types of antenna array structures at the cellular base station: a uniform linear array (ULA) and a uniform planar array (UPA). In addition to FP and channel hardening, we analyze the large system potential (LSP) which measures the asymptotic ratio of the expected power in the desired channel to the expected total interference power when both the antenna and user numbers grow. LSP is said to hold when this ratio converges to a positive constant. The results demonstrate that while FP is guaranteed in ray-based channels, CH may or may not occur depending on the nature of the model. Furthermore, we demonstrate that LSP will not normally hold as the expected interference power grows logarithmically for both ULAs and UPAs relative to the power in the desired channel as the system size increases. Nevertheless, we identify some fundamental and attractive properties of massive MIMO in this limiting regime.