Energy Efficient Reconfigurable Intelligent Surface Enabled Mobile Edge Computing Networks With NOMA

Abstract

Reconfigurable intelligent surface (RIS) has emerged as a promising technology for achieving high spectrum and energy efficiency in future wireless communication networks. In this paper, we investigate an RIS-aided single-cell multi-user mobile edge computing (MEC) system where an RIS is deployed to support the communication between a base station (BS) equipped with MEC servers and multiple single-antenna users. To utilize the scarce frequency resource efficiently, we assume that users communicate with BS based on a non-orthogonal multiple access (NOMA) protocol. Each user has a computation task which can be computed locally or partially/fully offloaded to the BS. We aim to minimize the sum energy consumption of all users by jointly optimizing the passive phase shifters, the size of transmission data, transmission rate, power control, transmission time and the decoding order. Since the resulting problem is non-convex, we use the block coordinate descent method to alternately optimize two separated subproblems. More specifically, we use the dual method to tackle a subproblem with given phase shift and obtain the closed-form solution; and then we utilize penalty method to solve another subproblem for given power control. Moreover, in order to demonstrate the effectiveness of our proposed algorithm, we propose three benchmark schemes: the time-division multiple access (TDMA)-MEC scheme, the full local computing scheme and the full offloading scheme. We use an alternating 1-D search method and the dual method that can solve the TDMA-based transmission problem well. Numerical results demonstrate that the proposed scheme can increase the energy efficiency and achieve significant performance gains over the three benchmark schemes.

Two-Stage Multiarmed Bandit for Reconfigurable Intelligent Surface Aided Millimeter Wave Communications

“…Lately, RIS has drawn much consideration as an up-and-coming technology that can suit future wireless systems demands [ 18 ], i.e., 6G and beyond. Hence, RIS has promoted wireless applications such as RIS-aided wireless power transfer [ 19 ], RIS-aided mobile edge computing [ 20 ], RIS-aided physical layer security [ 21 , 22 ], RIS-aided UAV communications [ 23 , 24 ], and mobility and handover management for RIS-aided wireless communications in high-speed trains [ 25 ].…”

Energy-Efficient Hybrid Offloading for Backscatter-Assisted Wirelessly Powered MEC with Reconfigurable Intelligent Surfaces

“…RIS-aided edge caching can minimize the network cost by optimizing the beamformers of the base station (BS), RIS phase shifts, and content placement at cache units [15]. In [16], the integration of BS and MEC with the aid of RIS is studied in which each WD can compute its task locally or partially/fully offload it to the BS. To support multiple WDs, the non-orthogonal multiple access (NOMA) protocol is considered.…”

Energy-Efficient Design of IRS-NOMA Networks

“…However, neither [13] nor [14] considered the EE performance of IRS-assisted MEC networks with NOMA, which is very important for system design to obtain the optimal tradeoff between achievable rate and consumed power. Motivated by the above-mentioned observations, in this paper, the EE maximization problem is studied in an IRS-assisted MEC network with NOMA.…”

“…Furthermore, recently application of IRS into NOMA-based MEC networks has been studied. In [13], the authors investigated an IRS-aided MEC system with NOMA. By jointly optimizing the passive phase shifters, the size of transmission data, transmission rate, power, and time, as well as the decoding order, they aimed to minimize the sum energy consumption.…”