A Joint Precoding Framework for Wideband Reconfigurable Intelligent Surface-Aided Cell-Free Network

By Zijian Zhang, Linglong Dai. IEEE Transactions on Signal Processing, 2020

356 citations recorded by the source corpus.

Thanks to the strong ability against the inter-cell interference, cell-free network is considered as a promising technique to improve network capacity. However, further capacity improvement requires to deploy more base stations (BSs) with high cost and power consumption. To address this issue, inspired by the recently developed reconfigurable intelligent surface (RIS) technique, we propose the concept of RIS-aided cell-free network to improve the capacity with low cost and power consumption. The key idea is to replace some of the required BSs by low-cost and energy-efficient RISs. Then, in a wideband RIS-aided cell-free network, we formulate the problem of joint precoding design at BSs and RISs to maximize the network capacity. Due to the non-convexity and high complexity of the formulated problem, we develop an alternating optimization framework to solve this challenging problem. In particular, we decouple this problem via fractional programming, and solve the subproblems alternatively. Note that most of the scenarios considered in existing works are special cases of the general scenario studied in this paper, and the proposed joint precoding framework can serve as a general solution to maximize the capacity in most existing RIS-aided scenarios. Finally, simulation results demonstrate that, compared with the conventional cell-free network, the network capacity under the proposed scheme can be improved significantly.

Subfields: Aerospace Engineering, Electrical and Electronic Engineering

View Paper: https://www.semanticscholar.org/paper/4f8e5505286899f38e4e02c33f5ee1709541152c

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Citations in the corpus

Smart Radio Environments Empowered by Reconfigurable Intelligent Surfaces: How It Works, State of Research, and The Road Ahead (2020, background): “In [172], the authors introduce the concept of RIS-aided cell-free network, which is aimed at improving the network”
Smart Radio Environments Empowered by Reconfigurable Intelligent Surfaces: How it Works, State of Research, and Road Ahead (2020, background): “In [171], the authors introduce the concept of RIS-aided”
Two-Timescale Channel Estimation for Reconfigurable Intelligent Surface Aided Wireless Communications (2019, background): “The precoding problem for multi-user MIMO is proven to be non-convex and NP-hard [9], hence researchers tried to find the near-optimal joint-beamforming solutions for RIS-aided communications [10], [11].”
Physics-Based Modeling and Scalable Optimization of Large Intelligent Reflecting Surfaces (2020, background): “In fact, most works assume the ideal case and set ḡuc = 1 [8], [17], [24], [38].”