Autonomous retransmission control with neighbour terminals for ad hoc networks

In ad hoc networks, radio interference and terminal´ mobility can cause frame losses. When the frame losses occur continuously, general datalink layer protocols regard it as a link failure and then notify it to network layer protocols. In conventional routing protocols, a source terminal initiates route discovery process to recover from the link failures on receiving the notifications even if the source terminal still has a valid route to a destination terminal. However, the route discovery requires a route request flooding and the flooding may consume limited network resources of ad hoc networks and that also degrades transmission efficiency. For solving the problems, several retransmission and relay control methods have been proposed. In these methods, neighbour terminals of a transmission route overhear transmitted frames and retransmit lost frames autonomously by using the overheard frames. However, the conventional retransmission methods have a disadvantage that they degrade the transmission efficiency under bursty frame loss interval. Moreover, conventional relay control methods suffer from a processing overhead and a slow adaptation problem under a sparse frame loss. In this paper, we propose an efficient and lightweight method that neighbour terminals adaptively retransmit lost frames considering a frequency of the losses. Computer simulations clarify the performances and the effectiveness of the proposed method.