Subarray Based Low Computational Design of Multiuser MIMO System Adopting Massive Transmit Array Antenna


IEICE TRANSACTIONS on Communications   Vol.E100-B    No.8    pp.1205-1214
Publication Date: 2017/08/01
Publicized: 2017/02/08
Online ISSN: 1745-1345
DOI: 10.1587/transcom.2016FGP0009
Type of Manuscript: Special Section PAPER (Special Section on Radio Access Technologies for 5G Mobile Communications System)
Category: Wireless Communication Technologies
massive MIMO,  multiuser,  block diagonalization,  subarray,  5G,  

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Massive multiple input multiple output (MIMO) communication system offers high rate transmission and/or support of a large number of users by invoking the power of a large array antenna, but one of its problem is the heavy computational burden required for the design and signal processing. Assuming the utilization of a large array in the transmitter side and much fewer users than the maximum possible value, this paper first presents a subarray based design approach of MIMO system with a low computational load taking into account efficient subarray grouping for the realization of higher performance; a large transmit array is first divided into subarrays based on channel gain or channel correlation, then block diagonalization is applied to each of them, and finally a large array weight is reconstructed by maximal ratio combining (MRC). In addition, the extension of the proposed method to two-stage design is studied in order to support a larger number of users; in the process of reconstruction to a large array, subarrays are again divided into groups, and block diagonalization is applied to those subarray groups. Through computer simulations, it is shown that the both channel gain and correlation based grouping strategies are effective under certain conditions, and that the number of supported users can be increased by two-stage design if certain level of performance degradation is acceptable.