In this article we compare the performance of two typical hyrbid beamforming structures for multiuser massive MIMO systems, i.e., the full- and partial-connection structures. Under the assumption of small angular spread for mmWave channels, given the analog precoder formed towards users and the zero-forcing digital precoder, we develop an explicit upper bound for the analog-and-digital-precoded channel gain of users, based on which the relationship between the two structures is investigated. The analysis results show that the full-connection structure is not always better than the partial-connection structure, and the regimes suitable for each structure are revealed. Simulations are conducted to validate the analysis results.
@article{arxiv.2006.10044,
title = {Hybrid Beamforming Structure for Massive MIMO System: Full-connection v.s. Partial-connection},
author = {Zheda Li and Shengqian Han and Andreas F. Molisch},
journal= {arXiv preprint arXiv:2006.10044},
year = {2020}
}