Constant Envelope Precoding in Multi-Cell Massive MIMO Systems: A High-Throughput Pilot Contamination Aware Scheme

Abstract

In this paper, we study the downlink transmission of a massive multiple input multiple output (M-MIMO) system in which constant envelop precoding (CEP) is utilized. We consider the realistic case of a multi-cell M-MIMO using full cooperation in the system, and aim to increase the system throughput by presenting a partially cooperative structure. We focus on a scenario where the channel state information (CSI) is imperfect due to pilot contamination, and seek to compensate for this effect using a pilot contamination aware CEP (PCA-CEP) algorithm. Finally, we attempt to reduce the system complexity by presenting a relaxed form of the proposed PCA-CEP algorithm. Numerical results demonstrate that for a large decrease in the system overhead in the partially cooperative structure compared to the fully cooperative one, the performance faces merely an insignificant degradation. Moreover, the effect of pilot contamination on the system performance is depicted and it is shown how the PCA-CEP algorithm can compensate for these effects. Also, this algorithm is compared with its relaxed form based on the comparison benchmarks of complexity and average data rate, and it is illustrated that in the relaxed PCA-CEP, in spite of a slight drop in performance, the complexity is reduced immensely.