A Cooperative Relay Scheme for Tactical Multi-hop Wireless Networks

In this paper, we propose and analyze a cooperative relay scheme for a time division multiple access (TDMA) protocol based tactical multi-hop wireless networks. In the proposed scheme, a neighbor of a relay node can relay a packet on behalf of the relay node in order to improve the throughput, without delay performance degradation. The neighbor node, that is, the cooperative node, may not have its own packet to transmit, whereas it can have a packet of the relay owing to the broadcast nature of the wireless networks, even though it is not the intended receiver. As the cooperative node takes the responsibility for relaying the packet, the relay node that is scheduled to relay the packet can transmit another packet. Cooperative nodes for the relay are selected by a simple distributed mechanism during the period of exchange of the control packets in each frame. Furthermore, an unnecessary packet relay by multiple node selection in multi-hop networks is prevented by the acknowledgement from the receiver. We formulate an analytical model on the basis of a Markov chain for the proposed scheme, which can be implemented over Rayleigh fading channels. The model is validated through various computer simulations. The analysis and simulation results show that the proposed scheme can effectively improve the throughput of a relay node, while maintaining the delay performance.