Hybrid Beamforming Structure for Massive MIMO System: Full-connection v.s. Partial-connection

TL;DR

This paper compares full-connection and partial-connection hybrid beamforming structures in massive MIMO systems, analyzing their performance differences and identifying regimes where each structure is preferable, supported by theoretical analysis and simulations.

Contribution

It provides an explicit upper bound for channel gain and reveals the conditions under which each hybrid beamforming structure performs better.

Findings

Full-connection is not always superior to partial-connection.

Regimes suitable for each structure are identified.

Simulation results validate the theoretical analysis.

Abstract

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.