Abstract
In this paper, we study a joint spatial division multiplexing (JSDM) beamforming scheme, which enables large-scale spatial multiplexing gains for massive multi-input multi-output downlink systems. In contrast to the conventional JSDM, which employs a block diagonalization method as a pre-beamformer, we aim to maximize sum-rate by applying minimum-mean-squared error (MMSE) approaches when designing a pre-beamformer and a multi-user precoder sequentially. First, to suppress inter-group interference, we design the pre-beamformer, which minimizes an upper bound of the sum mean-squared-error in the large-scale array regime. Then, to mitigate same-group interference, we present the multi-user precoder based on the weighted MMSE (WMMSE) optimization method, which requires the same channel state information overhead as the conventional JSDM. Also, in order to reduce the computational complexity, we compute deterministic equivalents of the WMMSE beamforming parameters to generate the beamformers by employing asymptotic results of large system analysis. Through simulation results, we confirm that the proposed two-step beamforming methods bring substantial performance gains in terms of sum-rate over the conventional JSDM schemes especially in a low and medium signal-to-noise ratio regime with comparable complexity.
Original language | English |
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Article number | 7880687 |
Pages (from-to) | 3029-3041 |
Number of pages | 13 |
Journal | IEEE Transactions on Wireless Communications |
Volume | 16 |
Issue number | 5 |
DOIs | |
Publication status | Published - 2017 May |
Bibliographical note
Funding Information:Manuscript received November 3, 2015; revised April 12, 2016, October 4, 2016, and January 10, 2017; accepted February 8, 2017. Date of publication March 17, 2017; date of current version May 8, 2017. This work was supported by the National Research Foundation of Korea funded by the Korea Government under Grant 2014R1A2A1A10049769 and Grant 2015R1C1A1A02036927. This paper was presented at the IEEE PIMRC, Valencia, Spain, 2016. The associate editor coordinating the review of this paper and approving it for publication was M. Kountouris.
Publisher Copyright:
© 2002-2012 IEEE.
Keywords
- Massive MIMO systems
- two-stage beamforming
- weighted MMSE
ASJC Scopus subject areas
- Computer Science Applications
- Electrical and Electronic Engineering
- Applied Mathematics