Relaying networks with Nth Best-Relay Selection over Nakagami fading channel

The coverage and spatial diversity enhancement in the wireless technology needs cooperative relaying strategy. Among a set of N relay elements, the Nth Best-Relay Selection scheme is proposed. The selection algorithm shows improvement in the bandwidth penalty and also increases the spatial diversity by employing a sub-optimal allocation considering the relay relative distance between the source and destination in a multi-hop cooperative systems. A single branch dual-hop network with adaptive Decode-and-forward (DF) and Amplify-and-forward(AF) cooperative diversity systems is considered. The analytical model of the proposed Nth Best-Relay selection scheme over single branch dual-hop system was developed and a closed-form expression was obtained. The BER (Bit error rate) and Outage probability using binary and quadrature phase shift keying modulation schemes (BPSK & QPSK) employing decode-and-forward (DF) and amplify-and-forward(AF) cooperative diversity systems over Nagakami fading channel was estimated. Results show that in the Nth best relay the diversity order is equal to (M - N + 2) where M is the number of relays.