Joint Resource Allocation and Configuration Design for STAR-RIS-Enhanced Wireless-Powered MEC

Abstract

In this paper, a novel concept called simultaneously transmitting and reflecting RIS (STAR-RIS) is introduced into the wireless-powered mobile edge computing (MEC) systems to improve the efficiency of energy transfer and task offloading. Compared with traditional reflecting-only RIS, STAR-RIS extends the half-space coverage to full-space coverage by simultaneously transmitting and reflecting incident signals, and also provides new degrees-of-freedom (DoFs) for manipulating signal propagation. We aim to maximize the total computation rate of all users, where the energy transfer time, transmit power and CPU frequencies of users, and the configuration design of STAR-RIS are jointly optimized. Considering the characteristics of STAR-RIS, three operating protocols, namely energy splitting (ES), mode switching (MS), and time splitting (TS) are studied, respectively. For the ES protocol, based on the penalty method, successive convex approximation (SCA), and the linear search method, an iterative algorithm is proposed to solve the formulated non-convex problem. Then, the proposed algorithm for ES protocol is extended to solve the MS and TS problems. Simulation results illustrate that the STAR-RIS outperforms traditional reflecting/transmitting-only RIS. More importantly, the TS protocol can achieve the largest computation rate among the three operating protocols of STAR-RIS.

Performance Analysis and Resource Allocation of STAR-RIS Aided Wireless-Powered NOMA System

“…From ( 23), (24), and ( 25), the time-allocation parameters are α t , α r , and α AP , and the powerallocation parameters are β t,T EP for U t and β r,T EP for U r . From (35), the average AoI for the TEP scheme is…”

“…Moreover, STAR-RIS provides a new degree-of-freedom for manipulating signal propagation, which increases the flexibility for network design [23]. To exploit the benefits of both WPC and STAR-RIS, a STAR-RIS-enhanced wireless-powered mobile edge computing system was proposed in [24], which was shown to improve the efficiency of energy transfer and task offloading by maximizing the total computation rate of all users. Furthermore, three practical protocols, including energy-splitting, mode-switching, and time-switching, were presented in [22].…”

Design and Performance Analysis of RIS-Aided DCSK-WPC System With Energy Buffer

“…In [33], a STAR-RIS assisted downlink MIMO-NOMA network was considered to investigate the energy-efficient resource allocation. To study the potential benefits of deploying STAR-RIS in wireless-powered transmission, there have been some initial works on STAR-RIS aided wireless-powered systems [34]- [37]. In [34], a STAR-RIS aided wireless-powered mobile edge computing system was investigated.…”

“…To study the potential benefits of deploying STAR-RIS in wireless-powered transmission, there have been some initial works on STAR-RIS aided wireless-powered systems [34]- [37]. In [34], a STAR-RIS aided wireless-powered mobile edge computing system was investigated. In [35], a STAR-RIS assisted wireless-powered IoT network was proposed, which adopts the time division multiple access (TDMA) scheme.…”

“…In [37], a STAR-RIS aided SWIPT system was proposed, where STAR-RIS employs the time-switching protocol. However, in [34]- [37], only single-antenna access points (APs) with the HU architecture were considered.…”