Enhancing Cooperative Communications via Reconfigurable Intelligent Surface-Assisted Strategies and the Integration of Low-Density Parity-Check Codes

Reconfigurable Intelligent Surfaces (RIS), also known as Intelligent Reconfigurable Surfaces (IRS), stand as one of the most promising technologies in wireless communications. Their remarkable attributes, including energy efficiency, low latency, and enhanced spectral efficiency, have drawn significant attention. This paper presents a novel approach to harnessing RIS for cooperative communications, seeking to replace traditional relay systems such as Decode and Forward (DF), Amplify and Forward (AF), and Coded Cooperation (CC). In this study, the RIS serves as a passive element within the communication system. The information originates from the sources and is transmitted to the RIS and destination in a single timeslot. RIS plays its role by reflecting the messages and redirecting them toward their intended destination. Additionally, this paper proposes an innovative combination of the RIS system with Low-Density Parity Check (LDPC) codes to enhance the overall system performance. Encoding of messages takes place at the source, while decoding occurs at the destination, facilitating the retrieval of the original information bits. Furthermore, the paper incorporates the Maximal Ratio Combining (MRC) technique to effectively combine signals for joint iterative decoding at the destination. The entire simulation was conducted using MATLAB software, with a focus on assessing key performance parameters (KPIs), namely the Bit Error Rate (BER) and Signal-to-Noise Ratio (SNR). Our proposed system was subjected to comparative analysis against various benchmarks, including a system without RIS, a system featuring coded cooperation relay, and several RIS-based systems with varying numbers of RIS surfaces. The objective was to not only demonstrate the enhanced BER performance brought about by our proposed system but also to determine the optimal conditions under which it operates most effectively. This research showcases the potential of RIS in transforming cooperative communications and paving the way for more efficient and reliable wireless networks.