Beamforming design for max‐min SINR in RIS‐based hybrid relaying

Abstract

Reconfigurable intelligent surface (RIS) technology is regarded as one of the important technologies for future 6G mobile communication networks. However, RIS can only passively reflect signals, rather than actively process received signals like the traditional relay. Therefore, a hybrid decode‐and‐forward (DF) relay and RIS‐assisted multiple‐input single‐output (MISO) multiuser downlink communication system is considered to combine the advantages of both. Then the beamforming at the base station (BS), the DF relay, and the phase vector of the RIS elements is jointly designed, aiming at achieving max‐min signal‐to‐interference‐plus‐noise ratio (SINR). Due to the non‐convexity caused by coupling between the beamforming vectors, the optimization problem is split into three semidefinite relaxation (SDR) sub‐problems, and then the alternate optimization method is adopted to solve the non‐convex problem. The numerical results verify the effectiveness and superiority of the proposed optimization algorithm in improving system performance compared with other benchmark schemes.

Hybrid RIS-assisted interference mitigation for heterogeneous networks

“…We use the fractional programming techniques suggested in [30] to convert the problem (22) into quadratic form in order to handle the non-convex logarithms and fractions. This leads to the following: by introducing auxiliary variables 22) is then transformed as (23).…”

A joint resource optimization allocation algorithm for NOMA‐D2D communication

“…Traditional optimization solutions have achieved satisfactory performance in terms of Quality of Service (QoS). However, future communication systems are seeking more favourable solutions to maximize throughput and support a larger number of D2D users allowed to access the system, in order to meet increasingly stringent QoS requirements [16][17][18]. In [19], a Deep Neural Network (DNN) framework to obtain joint power allocation solutions for the source and relay nodes is proposed.…”