Performance of Dual-Hop Transmissions with Fixed Gain Relays over Generalized-K Fading Channels

We present the end-to-end performance of dual-hop wireless communication systems with non-regenerative fixed gain relays operating over independent not necessarily identically generalized-K (K_G) fading channels. New closed-form expressions are derived for the moments of the end-to-end signal-to-noise ratio (SNR), while the corresponding moment- generating function (MGF) is accurately approximated with the aid of Pade approximants theory. Useful performance criteria are studied; the average end-to-end SNR and the amount of fading, which are expressed in closed form, the average bit-error probability for several coherent, noncoherent, and multilevel modulation schemes, and the outage probability, which are both accurately approximated using the well-known MGF approach. Furthermore, novel closed-form expression is obtained for the gain of semi-blind relays over K_G fading channels. The proposed mathematical analysis is complemented by various performance evaluation results, which demonstrate the accuracy of the theoretical approach.