Ticket-based Multiple Packet Broadcasting in Delay Tolerant Networks

In delay tolerant networks (DTNs), broadcasting is an important routing function that supports the distribution of data to all users in the network. Efficient broadcasting in DTNs is a challenging problem due to the lack of continuous network connectivity. In this paper, we consider the limited bandwidth scenario for DTN broadcasting. Our scheme aims to provide a ticket-based multiple packet broadcasting protocol for a DTN that follows the human mobility patterns – Levy walks and communitybased mobility. Our proposed protocol has two steps: packet selection and relay node selection. Packet selection takes place when two nodes come into contact with each other. It is based on a packet priority ranking scheme, which considers the number of tickets associated with each packet. Relay node selection will consider two parameters: global active level and local active level. Global active level is used for determining when the ticket partition is needed, and local active level is used to decide how the tickets should be partitioned. Each local active level corresponds to the activity level in a grid of 2-D broadcast space. Compared with epidemic, time-based, and hop-count-based schemes, our ticket-based packet priority ranking scheme, which considers the mobility patterns and the node active levels, has the best performance in our simulation. The simulation results show the good performance of our proposed scheme in DTN broadcasting, both in synthetic and real mobility traces.