A joint precoding framework for wideband reconfigurable intelligent surface-aided cell-free network
Zijian Zhang, Linglong Dai
备注：
Published in IEEE TSP. This joint precoding framework considers the general case of multiple BSs, multiple RISs, multiple users, multiple antennas at both BSs and users, and multiple carriers, so it can be also used for other special cases in which some of these parameters are single. The simulation codes are provided at: http://oa.ee.tsinghua.edu.cn/dailinglong/publications/publications.html
发表信息：
IEEE Trans. Signal Process., vol. 69, pp. 4085-4101, Jun. 2021
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.
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