A Geographic-Based Approach to Relay Selection for Wireless Ad Hoc Relay Networks

Abstract

In this paper, we propose a novel relay selection scheme based on geographical information, aiming to minimize the symbol error probability (SEP) for wireless ad hoc relay networks. The proposed scheme utilizes only the source-relay and relay-destination distances as selection criteria to choose the best relay. In particular, such geographical information is often available during network initialization. Thus, the proposed scheme does not need extra procedures to examine which relay has the best channel quality and, hence, reduces significantly the computational complexity. By contrast, most existing relay selection schemes rely on strict channel state information (CSI) and coherent time intervals, drastically increasing the difficulty in practical realizations, especially for large relay networks in which the fading channels are sufficiently fast-varying. In our scheme, the accuracy of the distance information is the main factor resulting in non-best relay selection. An ideal scheme (in which the distances between nodes are exact) and a practical scheme (in which there exists distance estimation errors) will be discussed respectively. Simulation results demonstrate the proposed relay selection method can efficiently improve the SEP performance and outperform the random relay selection scheme.Keywords-Cooperative diversity; wireless ad hoc relay networks; relay selection; decode-and-forward (DF); symbol error probability (SEP)

Error Performance Analysis Using Cooperative Contention-Based Routing in Wireless Adhoc Networks

“…Disaster management operations and battalion of soldiers are the example of applications of such cooperative ad-hoc wireless networks. This paper propose a protocol CoopGeo [1] [4], based on position location of nodes obtained using GPS technology [7].…”

“…In traditional geographic routing protocols, each node exchanges periodic one-hop "Beacons" to determine the position of its neighbours [2] [4]. Since these beacons can create severe problems in real deployments due to the highly dynamic and error-prone nature of wireless links, it uses Beacon-less geographic routing protocol (BLGR) [3].…”

“…A geographic relay selection scheme [4] based on the knowledge of location information of nodes. By jointly combining the source-relay and relay-destination distances, the optimal relay offering the best cooperative link can be efficiently determined.…”

“…The Selection metric [1] [3] [4] [5] is the distance parameters that depends on source-relay and relay-destination distances that indicates the SER performance [1] at the destination. The relay selection process takes place after the forwarder selection whenever the demand for cooperation is announced by a forwarder.…”

“…In this case, a new contention period will be allocated for relay selection. The relay selection process, in this paper, is based on the following selection criterion [4], Here m i is treated as our relay selection metric, which indicates the SER performance at the forwarder-the smaller the metrics is, the better the resulting SER performance [4] will be. Therefore, the best relay can be determined according to the following criteria *Smaller the metrics, better the resulting SER performance.…”