Capacity Analysis of a Hybrid Beamforming System with the Characteristics of Channel Clustering

초록

Hybrid beamforming (HBF) for space division multiple access is a promising technique to improve the capacity of the downlink multiuser multiple-input multiple-output system by exploiting the advantages of smart antenna technologies. This paper considers an M (the number of transceivers) by N (the number of antennas per transceiver) HBF structure, where the total M·N antennas are implemented as a uniform circular array antenna. A user selection algorithm in the HBF system is important to achieve spatial and multiuser diversity. To achieve spatial and multiuser diversity, a base station in the HBF system selects multiple users who have high channel gain, taking the channel clustering nature into consideration. Users report the channel state information that was calculated taking the angle-of-departure (AOD) into consideration and the base station selects multiple users to be served on the basis of the received channel state information from users. This paper mathematically derives the capacity of the HBF system and evaluates the performance of the HBF system in terms of the number of AOD representation bits, the number of transceivers, and the number of antennas per transceiver.

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