Research Of DTN Routing Protocol And Its Application In Congestion Control Mechanism

DTN(Delay Tolerant Network)is characterized by intermittent connectivity,varied and unpredictably long delay,asymmetric data rate and high error rate.Most of the time,a complete and reliable end-to-end path does not exist in DTN,which indicates that traditional routing protocol and congestion control policy can not work well in it.It has always been a hot theme to find suitable and well-behaved routing protocols and congestion control strategies.Epidemic and PROPHET(Probabilistic routing protocol using history of encounters and transitivity)are basic routing protocols introduced by researchers.Epidemic floods messages to each node it encounters,which can spread messages into DTN at a high speed.However,it uses significant resources.PROPHET selects a next hop using delivery predictability based on node encounters and transitivity,which saves resources.But it also causes a slow start issue in spreading messages.What’s more,it doesn’t consider the fact that node buffer occupancy should be involved in forwarding decisions.In order to address the above issue,this paper proposes a new routing protocol called PROPHETSE(PROPHET with Source Epidemic)on the basis of Epidemic and PROPHET.The proposed routing protocol not only can spread messages rapidlly into the DTN network,but also takes into account the influence of node buffer occupancy to forwarding.The simulation results denote that PROPHET-SE can forward more messages successfully at a low cost of overhead and delay.Furthermore,this paper carries out a futher research about the congestion control of PROPHET-SE routing potocol and advises a message drop policy based on normalized hybrid parameter.According to our simulation results,the given message drop policy can deal with network congestion well so that it provides a better balance level in delivery probability,overhead and average delay.