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Can Dynamic TDD Enabled Half-Duplex Cell-Free Massive MIMO Outperform Full-Duplex Cellular Massive MIMO?

Chowdhury, A and Chopra, R and Murthy, CR (2022) Can Dynamic TDD Enabled Half-Duplex Cell-Free Massive MIMO Outperform Full-Duplex Cellular Massive MIMO? In: IEEE Transactions on Communications, 70 (7). pp. 4867-4883.

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Official URL: https://doi.org/10.1109/TCOMM.2022.3174162


We consider a dynamic time division duplex (DTDD) enabled cell-free massive multiple-input multiple-output (CF-mMIMO) system, where each half-duplex (HD) access point (AP) is scheduled to operate in the uplink (UL) or downlink (DL) mode based on the data demands of the user equipments (UEs), with the goal of maximizing the sum UL-DL spectral efficiency (SE). We develop a new, low complexity, greedy algorithm for the combinatorial AP scheduling problem, with an optimality guarantee theoretically established via showing that a lower bound of the sum UL-DL SE is sub-modular. We also consider pilot sequence reuse among the UEs to limit the channel estimation overhead. In CF systems, all the APs estimate the channel from every UE, making pilot allocation problem different from the cellular case. We develop a novel algorithm that iteratively minimizes the maximum pilot contamination across the UEs. We compare the performance of our solutions, both theoretically and via simulations, against a full duplex (FD) multi-cell mMIMO system. Our results show that, due to the joint processing of the signals at the central processing unit, CF-mMIMO with dynamic HD AP-scheduling significantly outperforms cellular FD-mMIMO in terms of the sum SE and 90 likely SE. Thus, DTDD enabled HD CF-mMIMO is a promising alternative to cellular FD-mMIMO, without the cost of hardware for self-interference suppression. © 1972-2012 IEEE.

Item Type: Journal Article
Publication: IEEE Transactions on Communications
Publisher: Institute of Electrical and Electronics Engineers Inc.
Additional Information: The copyright for this article belongs to the authors.
Keywords: Cells; Channel estimation; Computational complexity; Cytology; Finite difference method; Iterative methods; MIMO systems; Scheduling; Time division multiplexing, Cell-free; Cell-free massive MIMO; Dynamic TDD; Greedy algorithms; Hardware; Interference; Massive MIMO; Modular optimizations; Pilot contaminations; Resource management; Sub-modular optimization, Program processors
Department/Centre: Division of Electrical Sciences > Electrical Communication Engineering
Date Deposited: 07 Sep 2022 04:39
Last Modified: 07 Sep 2022 04:39
URI: https://eprints.iisc.ac.in/id/eprint/76534

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