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On the Sum Capacity Achieving Precoders and Their CSI Requirements for MIMO-BC
Journal
IEEE Communications Letters
ISSN
10897798
Date Issued
2022-07-01
Author(s)
Kumar, Anil
Appaiah, Kumar
Pillai, Sibi Raj
Abstract
Dirty paper coding (DPC) precoders achieve the sum capacity of Gaussian MIMO broadcast channels. However, most systems employ zero-forcing (ZF) and MMSE precoders that are near-optimal at high SNR if the base station (BS) has a large number of antennas, but achievable sum rates with ZF and MMSE precoders are significantly below sum capacity otherwise. We show that capacity achieving DPC precoding requires CSI that scales only as O(M2) for M-antenna user (not full CSI as is generally assumed) irrespective of the number of BS antennas. Moreover, easily computable generalized decision feedback equalizers significantly outperform MMSE and ZF precoders.
Subjects