Two-Level Community-Based Routing in Delay Tolerant Networks

Delay tolerant networks can not maintain end-to-end connectivity. Thus the routing is one of the critical issues. As we known, the two-level community model including the small community and the big community is proposed for the first time. In the same small community, any two member nodes are friends with each other. And in the same big community which is constructed of some small communities, any two communities have some pairs of friend nodes between them. Based on this model, a two-level community-based routing (TLCR) algorithm is presented in delay tolerant networks. In TLCR, according to the location of packet holder including inside the small community of destination node, inside of the big community and outside of the small community of destination node, and outside of the big community of destination node, the different packet forwarding strategies are investigated. The number of relay nodes selected by a packet holder is decreasing with the holder's location from inside of the small community of destination node to outside of the big community of destination node. The probability of the source node successfully delivers the packet to the destination node and the copies number corresponding with the above three locations are analyzed, respectively. The simulation results show that TLCR not only improves the delivery ratio but also greatly reduces the resource cost.