The effect of cooperation level in cooperative systems

The performance of a cooperative coded system in terms of cooperation level for various values of inter-user channel quality, average SNR, and the type of detection for a (7,4) Hamming code is presented. As concluded from simulations, for each inter-user channel quality, the optimum cooperation level is different. When the time varying part of the inter-user channel is negligible, which depends on the existing LoS component in it, the optimum cooperation level is 50% where the user and its partner have the same cooperation share and maximum diversity gain is achieved. When a soft decoder is used, for high inter-user channel quality and high SNR, the optimum cooperation level is also 50%. In low inter-user channel quality, or when hard decoding is used, the optimum cooperation level is lower than 50% and, depending on the above parameters, it can even be zero, i.e., cooperation in low values of the parameters degrades the performance