SEP of a scaled selection combining scheme with decode and forward relaying for MPSK signaling

Abstract

The performance analysis of a cooperative diversity system with decode and forward relaying has drawn considerable attention recently. The use of conventional maximal-ratio combiners does not suit well for a cooperative diversity scenario and the assumption of no detection errors at the relay is also practically hard to achieve. Hence, we propose a scaled selection combining scheme, where we scale the relay-todestination links by a deterministic positive scale factor to incorporate the effect of the source-torelay links. At the destination, we choose a link which has maximum scaled instantaneous signalto-noise ratio (SNR), from a set which consists of instantaneous SNR of the source-to-destination link and the scaled instantaneous SNRs of the relay-to-destination links. For a flat Rayleigh fading environment with statistically independent links, the end-to-end symbol error probability (SEP) of this scheme for M -ary phase-shift keying is derived in closed form. We also give a method of obtaining the optimum scale factor that minimizes the end-to-end SEP. The analysis is validated through extensive simulations.Keywords -Decode and forward (DF) protocol, Mary phase-shift keying (MPSK), Rayleigh fading, scaled selection combining, symbol error probability (SEP). I. IntroductionCooperative diversity is an effective technique to combat fading; hence the performance analysis of cooperative diversity systems is essential. The concept of cooperative diversity with decode and forward (DF) relaying has been introduced and studied in [1], [2]. DF relaying has drawn much attention recently because of its signal regenerating characteristics. Previous works [3], [4] on MRC based cooperative diversity systems assume that the relay forwards the source symbol only if it correctly detects that symbol; otherwise it does not forward. A serious drawback of this scheme is that the system will not see any diversity if the channel condition of the source-to-relay link is poor and also it misses a case that successive error occurs at the source-to-relay link and relay-to-destination link gives a

Relay selection in amplify and forward protocol utilizing low bandwidth

“…Seunghoon Nam [13] proposed a method to select a set of cooperating relays in order to reduce the total transmission time of an amount of data. M. D. Selvaraj [14] proved that the use of conventional maximal-ratio combining technique is not suitable for a cooperative diversity network. Hence, proposed a scaled selection combining scheme, where the relay-to-destination links is scaled by a fixed positive scale factor.…”