On-Demand Decode and Forward Cooperative MAC for VoIP in Wireless Mesh Networks

The employment of wireless mesh networking in real- life scenarios has attracted substantial research interest in recent years and in this context VoIP has become a ubiquitous application. However, it has been demonstrated that VoIP transmissions over a multihop network may still remain inadequate in terms of their high packet-loss ratio and network- induced delays. To alleviate these limitations, we propose a novel distributed MAC-layer cooperation protocol, which is based on the decode-and-forward regime, whilst relying on the lowest possible control packet overhead. Furthermore, we employ several improvements across the protocol stack, including an improved PHY-layer, based on three- stage turbo-style differential detection, packet aggregation in the MAC-layer, as well as on adjusting the retransmission limit of each packet in order to reduce the delay imposed when employing cooperation. We characterize our improved system in a Wireless Mesh Network (WMN) scenario using the OMNeT++ network simulator and compare it to an 802.11g-based benchmarker. As a benefit of these techniques, we have observed up to 10-fold reduction in the energy consumption per bit, despite increasing the number of simultaneous calls supported by up to 9, when the number of hops between the sources and destination is 6.