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

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, inspi...

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Bibliographic Details
Published in:IEEE transactions on signal processing 2021, Vol.69, p.4085-4101
Main Authors: Zhang, Zijian, Dai, Linglong
Format: Article
Language:English
Subjects:
Broadband
Cell-free network
Convexity
Energy efficiency
joint precoding
Low cost
Mathematical programming
Measurement
Optimization
Power consumption
Power demand
Precoding
Programming
Radio equipment
reconfigurable intelligent surface (RIS)
Reconfigurable intelligent surfaces
Simulation
wideband
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Summary: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.
ISSN:1053-587X
1941-0476
DOI:10.1109/TSP.2021.3088755