Performance Analysis and Power allocation for Multi Relay Wireless Cooperative NOMA Networks with Diversity Combining strategies

This paper presents, multiple relay selection strategy and comparison of different diversity combining techniques at the receiver in Non Orthogonal Multiple Access (NOMA) based wireless cooperative networks .Three different diversity combining strategies Selection Combining(SC) ,Equal Gain Combining (EGC) and Maximal Ratio Combining(MRC) were examined under Rayleigh fading channel conditions and Amplify and Forward relaying strategy. Analytical results were developed to demonstrate Symbol Error Rate (SER) performance. The simulation results revealed the benefit of selecting the MRC scheme instead of SC and EGC which were applied to combine the multiple received signals from selected relays .The effective Signal to Noise Ratio (SNR) for all the wireless channel links are calculated and multiple relay selection is done by choosing relays having maximum effective SNR. Performance analysis on MRC scheme was carried out for Fixed Power Allocation and Optimal power allocation using Lagrangian method and the results affirmed better performance for optimal power allocation technique.