An Improved Buffer Scheme in Delay Tolerant Networks

Delay Tolerant Networks (DTNs) are a class of emerging networks where disconnections may occur frequently due to propagation phenomena, node mobility, and power outages. Delay is inevitable in DTNs, thus, making better use of buffer space to maximize the packet delivery rate is more important than concentrating on how to decrease the delay. In this paper, we improve the buffer scheme of Epidemic Routing, which is a well-known routing protocol in DTNs. Epidemic Routing utilizes the FIFO buffer management scheme to manage the queuing. However, Epidemic Routing is still very sensitive to the buffer size. Epidemic Routing, furthermore, can only achieve good performance with respect to infinite buffer size due to that a node may have enough space to store lots of messages in its buffer and carry them along for long periods of times until appropriate forwarding opportunities arise. Once there is not enough buffer size, then the performance of Epidemic Routing will fall down hastily. We propose a new buffer scheme in Epidemic Routing, named Location and Direction Aware Drop Scheme (LDDS). LDDS utilizes the location and moving direction information of nodes to determine the drop sequence. A node can get the location and moving direction information of other nodes by receiving beacon packets periodically from anchor nodes and referring to received signal strength indicator (RSSI) for the beacon. In particular, LDDS is able to guarantee the high packet delivery ratio under small buffer size.