In this paper, we focus on single-selection oppor- tunistic relaying with the decode-and-forward protocol over Rayleigh fading channels. The end-to-end average signal-to-noise ratios (SNR) and ergodic capacities of both proactive and reactive opportunistic relaying are analyzed as a closed form in a high source-to-relay SNR regime where all link qualities satisfy the required SNR. The derived results are then used to prove that the end-to-end average SNR for the proactive scheme is greater than or equal to that of the reactive scheme. In addition, it is proven that the SNR and ergodic capacity differences of these schemes are broaden as the number of relays increases. The end-to-end ergodic capacities of the two methods are investigated both with and without the threshold using simulations. In this paper, we analyze the end-to-end average signal-to- noise ratios (SNR) and the ergodic capacities of two oppor- tunistic DF relaying schemes over dual-hop Rayleigh fading channels based on the assumption of a high source-to-relay SNR regime such that all link qualities attain the required SNR threshold. In addition, we use the results to verify that the end- to-end average SNR of the proactive scheme is greater than or equal to that of the reactive scheme. Moreover, it is derived how much the proactive scheme is better than the reactive one for given environment. In company with the SNR analysis, the end-to-end ergodic capacities of the two methods are also analyzed, and their performances are examined via simulations when a threshold is present. This paper is organized as follows: Section II presents the characteristics of the two opportunistic DF relaying schemes. Section III derives the end-to-end average SNRs of the two methods and proves the average SNR of P-DF outperforms that of R-DF. In addition, the SNR difference between two schemes are inspected according to the number of relays and link qualities of source-to-relay and relay-to-destination. Section IV analyzes the end-to-end ergodic capacities of the two types, and Section V provides the simulation results and discussion. Finally, our conclusions are presented in Section VI.
['Sungeun Lee', 'Myeongsu Han', 'Daesik Hong']
Average SNR and Ergodic Capacity Analysis for Proactive and Reactive DF Relaying over Rayleigh Fading Channels