Abstract
In this paper we evaluate the outage probability in cooperative networks using the channel conditions in order to select the best four relays from a set of N relays and then the chosen relays are used for cooperation between the source and the destination. Expressions for outage probability are derived for a frequency flat Rayleigh-fading environment by using theoretic analysis of the probability function (PDF) and the cumulative density function (CDF) of the received signal-to-noise ratio (SNR). Simulation studies show the outage probability for different numbers of available relays N and the impact on system performance for different numbers of available relays N and the resultant diversity of the proposed modified quasi-orthogonal scheme. © 2012 University of Split.