Achievable sum-rate analysis for massive MIMO systems with different array configurations

In this paper, we investigate the achievable ergodic sum-rate for multiuser massive multiple-input multiple-output systems, where different array configurations such as uniform linear arrays (ULAs), uniform planar arrays (UPAs) and uniform circular arrays (UCAs), are deployed at the base station (BS). The investigation is carried out based on a three dimensional spatial propagation channel model by taking into account both the azimuth and elevation angular domains. We first investigate the value of the inner product of two channel vectors, for which closed-form expressions are derived with different array configurations in line-of-sight channel. After that, the effects of the BS antenna number, the angles of departure of users, and the inter-antenna spacing on the inner product, further, on the achievable ergodic rate, are investigated. Finally, theoretical results are verified via numerical simulations, which is shown that deploying ULAs outperforms the other array configurations (UPAs and UCAs) in terms of improving the achievable ergodic rate and the larger inter-antenna spacing can contributes substantially to the achievable sum-rate.