A Buffer Management Strategy on Spray and Wait Routing Protocol in DTNs

Due to unpredictable node mobility and the easily-interrupted connections, routing protocols in DTNs commonly utilize multiple message copies to improve the delivery ratio. A store-carry-and-forward paradigm is also designed to assist routing messages. However, excessive message copies lead to rapid consumption of the limited storage and bandwidth. The spray and Wait routing protocol has been proposed to reduce the network overload caused by the storage and transmission of unrestricted message copies. However, there still exist congestion problems when a node's buffer is quite constrained. In this paper, we propose a message Scheduling and Drop Strategy on spray and wait Routing Protocol (SDSRP). To improve the delivery ratio, first of all, SDSRP calculates the priority of each message by evaluating the impact of both replicating and dropping a message copy on delivery ratio. Subsequently, scheduling and drop decisions are made according to the priority. Finally, we conduct extensive simulations based on synthetic and real traces in ONE. The results show that, compared with other buffer management strategies, SDSRP achieves higher delivery ratio, similar average hop counts, and lower overhead ratio.