On the BER Analysis of RIS-aided DF cooperation

Abstract To address the issue of insufficient modeling of bit error rate (BER) in RIS-assisted decoding and forwarding (DF) relay communication systems under complex fading environments, this paper proposes a RIS-assisted DF relay system model and conducts system reliability analysis under generalized-K fading channels. By utilizing the Meijer-G function, we derive a closed-form expression for the moment-generating function (MGF) of the end-to-end signal-to-noise ratio (SNR), overcoming the modeling bottleneck in composite fading channels. Based on this, we further derive a closed-form solution for the system BER. The MGF and BER closed-form solutions derived in this study provide a theoretical basis for evaluating the performance of communication systems under generalized-K distribution fading channels. Simulation analysis results indicate that modeling under generalized-K fading channels is more aligned with real-world complex environments and demonstrates better BER performance compared to traditional Rayleigh fading models. The proposed RIS-assisted DF relaying scheme significantly outperforms schemes with only relays or only RIS assistance in terms of BER performance. Increasing the number of RIS reflectors (N) or deploying multiple RIS units can significantly reduce system BER and enhance reliability. Simulation results validate the correctness of the theoretical analysis and the effectiveness of the proposed scheme in complex fading environments.