Unified Performance Analysis of C–MRC and LAR Decode–and–Forward Schemes

In this paper, we study the performance of two important types of decode–and–forward (DF) relaying schemes proposed for cooperative diversity (CD) systems, namely, cooperative maximum–ratio combining (C–MRC) and link adaptive regeneration (LAR). In particular, we provide a unified framework for the error rate performance analysis of C–MRC, LAR–αinst, and LAR–α DF schemes for multi–branch CD systems consisting of a source, a destination, and multiple relays. Based on this framework, we provide accurate expressions for the performance of the considered CD systems for high signal–to–noise ratios and Rayleigh fading. The developed asymptotic performance results facilitate a performance comparison with other relaying schemes and reveal that while full diversity is achieved by C–MRC and LAR–αinst, LAR–α is, in general, unable to collect full diversity.