Scheduling schemes for N-node cooperative networks

In this paper, we consider an amplify-and-forward cooperative network composed of N nodes. Here we focus on the scheduling problem which consists in assigning the roles {source, relay} to the N nodes. Our target is to investigate and develop relay selection policies that can be used in amplify-and-forward cooperative systems. For fairness and simplicity issues, we assume that a node is chosen as a source in a Round Robin fashion. On the other hand, two relay selection schemes are proposed. In the first scheme, the relay selection problem is addressed under the knowledge of nodes positions and the relay is chosen to be the nearest neighbor of the source. This relay selection method combined with the RR source selection method will be called Network Topology based scheduling (NT-based scheduling). In the second scheme, the relay selection algorithm is based on the instantaneous channels qualities and the relay is the node with the best direct link in term of instantaneous signal-to-noise ratio (SNR). Since this second method requires much signaling which degrades the scheme performance, a channel feedback reduction method is proposed with the use of a threshold T. The relay selection method which use the proposed feedback reduction technique combined with the RR source selection method will be called semi Channels Qualities based scheduling (semi CQ-based scheduling). Simulation results will be provided in order to compare the performance of these scheduling schemes and to show the high performance provided by our proposed algorithms.