Impact of Hardware Impairments on IRS-Assisted MISO-SCMA Communication Systems

Abstract

This work investigates an intelligent reflecting surfaces (IRS)-assisted multiple inputs and single output (MISO)sparse code multiple access (SCMA) system under the influence of hardware impairments (HIs) and nonlinear power amplifiers (NPAs) by considering phase-shift design. To address the IRS phase-shift design, we introduce a non-iterative maximum energy antenna index selection (MAIS) strategy. The proposed MAIS method significantly lowers computational burden as compared to iterative methods while maintaining strong performance. We evaluate the system’s average bit error rate (BER), and achievable sum-rate both with and without the presence of HIs and NPAs. The findings confirm that these impairments severely deteriorate SCMA performance (2-4 dB). In addition, the influence of critical system parameters, including the IRS size, number of transmit antennas, and different IRS phase-shift selection techniques, is comprehensively examined. Index Terms-Intelligent reflecting surfaces (IRS), nonlinear power amplifier, IQ imbalance, BER and sum-rate performance, sparse code multiple access (SCMA).