Conventional Relay Selection Scheme Research Articles

Interference-Aware Relay Selection Scheme for Two-Hop Relay Networks With Multiple Source–Destination Pairs

An interference-aware relay selection scheme is proposed for two-hop relay networks with multiple source–destination (S–D) pairs, each of which is assisted by a relay selected from the candidates. We address the interference from relays to their nonintended destinations, and the interference level at any destination is jointly affected by relay selections of all S–D pairs. Upper and lower bounds of the two-hop transmission rate are derived, and the joint impact of the interference from multiple relays is decoupled to each S–D pair. Based on these bounds, an interference-aware relay selection metric for each S–D pair is proposed, which reflects both the relay-assisted two-hop rate and the induced interference to other destinations. The decoupled metric enables us to formulate the relay selection as a weighted bipartite matching problem, with the S–D pairs and the candidate relays as the two sides. Both the centralized scheme based on the Hungarian algorithm and the distributed scheme based on matching games are presented. Simulation results show that the distributed scheme performs nearly the same as the centralized scheme, and both schemes substantially outperform the conventional min–max relay selection scheme in terms of network sum rate.

Opportunistic Decode-and-Forward Relaying with Interferences at Relays

In this paper, a decode-and-forward cooperative interference-limited multiple relay network is considered. An efficient relay selection strategy and its performance analysis are proposed, where only the relay nodes are affected by multiple interferences. In the proposed relay selection scheme, the selected relay is not always used, depending on the power of interferences and the channel state information of all links, while the direct path between source and destination is always used. For analytical tractability the distribution of interference-limited channel is approximated as an exponential distribution with high accuracy. Analysis of cooperative networks with interference-limited relays can be performed using the approximate exponential distribution by the same methods which have been used without interferences. We derive the bit error probability and outage probability of the proposed opportunistic max-min relay selection (OMRS) scheme in independent non-identically distributed Rayleigh fading channels. Numerical results present the superiority of OMRS over the conventional relay selection scheme which always uses the selected relay path. The exactness of the approximate analysis for interference-limited relays is also shown in numerical results.

Symbol Error Rate Analysis and Power Allocation for Adaptive Relay Selection Schemes

In this paper, we analyse the symbol error rate (SER) performance of adaptive relay selection schemes (ARS) in a general dual-hop multiple-relay network. Specifically, we provide a closed-form SER expression for ARS which is tight over the whole signal-to-noise ratio (SNR) region. In addition, the derived SER can be readily extended to conventional relay selection schemes, i.e. amplify-and-forward relay selection (AF-RS), perfect decode-and-forward relay selection (PDF-RS), adaptive decode-and-forward relay selection (ADF-RS), and cooperative-maximum-ratio-combining decode-and-forward relay selection (CDF-RS). Transmit power allocation based on the simplified SER is presented to improve the system performance. The analytical results are verified by computer simulations.