Waveform Decreasing Multi-copy Based Routing in Low Node Density DTNs

Delay Tolerant Networks (DTN) is one of the mobile wireless networks that topology logic may change frequently. Variable topology logic characteristics lead to several low efficiency routing problems, and in which how to increase the routing efficiency in low node density is an important issue that must be solved. The mainstream DTN routing strategy is multi-copy based routing and in order to solve the problem of flooding scale, the routing strategy always makes the messages flooding scale change under specific conditions called Waveform Decreasing Multi-copy (WDM) routing strategy: the flooding scale could increase or decrease. In this paper, we propose an improved routing strategy named WDM routing strategy aimed to improve the routing efficiency under low node density in DTN environment. Using several special mechanisms, the improved WDM routing strategy can obtain good performance in the case of low node density: transfer new messages first, special message transfer list, and the way of flooding scale changed. The simulation results show the WDM routing significantly improve the performance than the two mainstream routing: the Spray and Wait routing and the MaxProp routing.