BER Analysis and Optimization for Continuous RIS-Enabled NOMA

TL;DR

This paper presents a comprehensive analysis and optimization of BER performance in a novel uplink CRIS-assisted NOMA system, demonstrating significant improvements over traditional schemes through joint power and RIS partitioning optimization.

Contribution

It introduces a new BER analysis for CRIS-assisted NOMA and proposes an optimization framework that enhances uplink performance by joint power allocation and RIS partitioning.

Findings

Optimized scheme eliminates BER floors in UL NOMA.

CRIS-assisted NOMA outperforms conventional OMA.

Analytical BER expressions validated by simulations.

Abstract

This letter investigates a novel uplink (UL) system that integrates power-domain non-orthogonal multiple access (PD-NOMA) with a continuous reconfigurable intelligent surface (CRIS). We analyze the effective CRIS-assisted channels under spatially correlated fading to accurately approximate the characteristic function of the cascaded channel. This allows the derivation of an expression for the bit error rate (BER), a key performance metric for UL PD-NOMA. We further utilize the derived BER expressions to introduce a joint optimization framework that minimizes the average BER via UL power allocation and dynamic RIS partitioning among the users. The analytical results are validated by simulations, and show that the proposed optimization scheme eliminates the BER floors that are associated with UL NOMA. The results also confirm the superiority of the optimized CRIS-NOMA scheme over conventional orthogonal multiple access (OMA) and non-optimized UL NOMA schemes.