Abstract
Energy efficiency is a key requirement for future network design, and user-centric (UC) cell-free (CF) massive multi-input multi-output (MIMO) networks can achieve over ten times the energy efficiency. Based on this, this paper studies a CF MIMO simultaneous wireless information and power transmission system and proposes a UC access point (AP) selection method and a trade-off performance optimization scheme for spectral efficiency and energy efficiency. In this system, users have both energy recovery and information transmission functions. According to the difference between the interference in the energy harvesting and information transmission process, a flexible AP selection scheme is designed. Blindly pursuing high spectral efficiency will result in waste of resources. This paper proposes an evaluation index that takes into account both energy efficiency and spectral efficiency, analyses the trade-off between energy efficiency and spectral efficiency, and jointly optimizes the AP selection scheme and the uplink (UL) and downlink (DL) time switching ratio to maximize the trade-off performance. Then, the non-convex problem is converted to a geometric planning problem to solve. The simulation results show that by implementing a suitable AP selection scheme and UL and DL time allocation, the information processing scheme on the AP side has a slight loss in spectral efficiency, but the energy efficiency is close to the performance of global processing on the central processing unit.
Highlights
The SEBy equipping base stations with massive multiple-input multiple-output (MIMO)networks, the spectral efficiency (SE) can be increased by at least 10 times compared with traditional cellular networks [1,2,3]
In the CF massive MIMO architecture, all access point (AP) are connected to a central processing unit (CPU) through a backhaul link, and the CPU is responsible for coordinating various resource allocations
1.2 Contributions In order to fill the above gaps, we studied the trade-off between EE and SE of the CF massive MIMO Simultaneous wireless information and power transmission (SWIPT) system, and proposed an evaluation index that takes both SE and EE into consideration
Summary
The SEBy equipping base stations with massive multiple-input multiple-output (MIMO). networks, the spectral efficiency (SE) can be increased by at least 10 times compared with traditional cellular networks [1,2,3]. Reference [37] researches the performance of a CF massive MIMO SWIPT system in which information and power are simultaneously transmitted to single-antenna information or energy users through a large number of spatially distributed single-antenna APs. the closed-form expressions of the recovered energy and DL/UL achievable rate are deduced. The simulation results show that CF massive MIMO can improve the performance of SWIPT by taking advantage of distributed transmission and reception with a large number of APs. Reference [38] considers a spatial stochastic network in which the Poisson point process is used to model APs randomly and the time switch protocol is used for SWIPT operation at the user.
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