Performance Analysis of Soft Information Relay Models

Traditional cooperative wireless networks suffer from error propagation to the destination in poor channel conditions. The incorrect decoding at the relay and low signalto-noise ratio (SNR) on the source-relay link causes significant degradation of the system. Thus, Soft Information Relaying (SIR) is presented as a robust technique to overcome this issue. This work studies the various decoder design techniques and associated soft noise distribution of the main SIR schemes and then introduces a noise amplification factor to reduce the effect of the relay link. It helps to model the distribution of log-likelihood ratio (LLR) distribution at the destination approximately Gaussian in parallel relay schemes. Further, the Bit Error Rate (BER) performance of each wireless relay scheme under single and multiple systems is evaluated. Also, the mutual information-based forwarding (MIF) SIR scheme outperforms all other traditional SIR schemes.