RIS improves multi-way user communication with smart interference control
RIS Aided Multi-Way Communication Systems based on SIC Decoding Techniques
Information Theory
Summary
When multiple people send messages through the same system, their signals can interfere and cause mistakes. The authors study a new system that uses a special reflective surface called an RIS to help users share information more smoothly. They test three ways to reduce these signal mix-ups, finding that which method works best depends on the size of the reflective surface. Their results show practical ways to improve wireless communication by carefully ordering how signals are treated and optimizing the reflection.
What this means in practice
- •For wireless network engineers: Enhance multi-user wireless communication by implementing optimized interference cancellation and RIS phase control to reduce errors in dense user environments.
- •For satellite communication operators: Improve full-duplex satellite links by using RIS-based SIC techniques to manage interference among multiple ground terminals.
Authors
Lingya Wang, Harry Leib
Abstract
This work considers reconfigurable intelligent surface (RIS) aided multi-way communication systems employing QPSK. The objectives of such system is to allow multiple users to exchange information, exploiting the full-duplex capabilities of RIS. The system under consideration comprises $K$ user terminals and an RIS with $N$ reflective elements. Each user terminal is equipped with one transmit and $M$ receive antennas. To mitigate inter-user interference caused by the full-duplex operation of the RIS, three successive interference cancellation (SIC) techniques are considered. We investigate three SIC ordering methods: $1)$ descending channel variances, $2)$ increasing mean square error, $3)$ optimization approach which maximizes the combined channel gain within the system. The bit error rate (BER) performance of these three SIC methods are evaluated using extensive Monte-Carlo simulations for different numbers of RIS elements, ranging from 4 to 64, and a varying number of transmitting users, ranging from 1 to 5. Additionally, an RIS phase shift optimization method for RIS with reflection elements of varying amplitudes is considered. In this case the previous SIC optimization technique is adapted to address phase-dependent amplitudes in RIS reflection elements. Simulation results indicate that in both ideal and varying amplitude scenarios, when the number of RIS elements is small, SIC with ordering based on increasing mean square error achieves the best BER performance. However, as the number of RIS elements increases, SIC ordering based on the optimization method achieves the best BER performance.