New power allocation schemes for AF cooperative communication over Nakagami-m fading channels

Three new power allocation schemes for a typical amplify-and-forward (AF) cooperative system over independent non-identical Nakagami-m fading channels are proposed in this paper. By analyzing the upper bound of the instantaneous SNR (signal-to-noise-ratio) at the destination using the inequity expression between arithmetic mean and geometric mean, we derive the average SNR and SER (symbol-error-rate) for M-ary phase-shift-keying (M-PSK) modulation scheme. Moreover, we seek to find optimal power allocation strategies that maximize the upper bound of average SNR or minimize the upper bound of average SER at the receiver side with total and single-link power constraints. Through carefully observing the expression structure of instantaneous SNR, an equivalent circuit form is abstracted. Meanwhile, a new power allocation scheme based on the equivalent circuit form is investigated. Monte Carlo simulation results are included to verify the effectiveness and superiority of these proposed new power allocation strategies.