Pilot Power Optimization for AF Relaying Using Maximum Likelihood Channel Estimation

Bit error rates (BERs) for amplify-and-forward (AF) relaying systems with two different pilot-symbol- aided channel estimation methods, disintegrated channel estimation (DCE) and cascaded channel estimation (CCE), are derived in Rayleigh fading channels. Based on these BERs, the pilot powers at the source and at the relay are optimized when their total transmitting powers are fixed. Numerical results show that the optimized system has a better performance than other conventional nonoptimized allocation systems. They also show that the optimal pilot power in variable gain is nearly the same as that in fixed gain for similar system settings.