Efficient Delay Tolerant Routing Protocols for Group Mobility

Since network disconnection will happen more frequently in mobile ad hoc network with group mobility model, the routing strategy proposed in delay-tolerant network could be applied for it. However, most of the current delay-tolerant routing protocols are designed based on the entity mobility model, not on the group mobility model. Motivated by this, we have proposed THREE routing schemes on the basis of one proposed delay-tolerant routing protocol called epidemic routing (ER) to make it perform more effectively for group mobility model.
The first one is called group-epidemic routing (G-ER). Through making use of the uniqueness of the group mobility models, one significant improvement measure has been proposed in which a group of nodes will be behaved as a single node. We treat each group as one individual unit during routing execution to substantially reduce the routing overhead and the resource requirement. To make better use of the rare contact opportunities in DTN, we propose the group based packet exchange, in which the contact of any two nodes from two groups will trigger the packet exchange between the two groups. The second one is named as the leader based group routing (LBGR) by making full use of group structure in group mobility. we consider the resource allocation in each group and propose the leader-dominating routing in LBGR to reduce the impact of the group dynamics on network performance. The third one is called purpose-movement assisted routing (PMAR) aiming for a more realistic mobility model, group mobility, which has been paid attention in many realistic scenarios. Different from the traditional store-carry-forward DTN routing strategy, in which nodes wait for the connectivity passively, PMAR employs nodes to actively create new connection by altering the node movement, and thus the packet could be delivered in an expedited manner. More importantly, the proposed PMAR could be taken as a component to be integrated into different DTN routings for group mobility to make them more aggressive in delivering packets. In this paper, we integrate PMAR into a previously proposed routing, group-epidemic routing (G-ER). PMAR could be triggered whenever some packets need to be delivered to the destinations in a faster way, but without any connection to their destinations. By extensive simulation we show that all three schemes outperform two traditional routing protocols, epidemic routing and DSR, in various network conditions.