Document Type : Research Paper
K.N. Toosi Universityan of Technology- Seyed Khandan- Tehran- Iran
K.N.Toosi University of Technology
Due to the increasing use of wireless communications, infrastructure-less networks such as Delay Tolerant Networks (DTNs) should be highly considered. DTN is most suitable where there is an intermittent connection between communicating nodes such as wireless mobile ad hoc network nodes. In general, a message sending node in DTN copies the message and transmits it to nodes which it encounters. A receiving node, if it is not the destination of the message, stores the message and transmits a copy of the message to nodes it meets. This process continues until the message reaches its destination or its lifetime expires.
Various DTN routing protocols have been proposed to reduce the number of copies and improve the message delivery probability. However, very few of them consider the energy constraint of mobile nodes in routing protocols. Mobile nodes especially smartphones and tablets are powered by batteries with limited energy. It is essential to consider energy constraint while designing routing protocols for DTNs. Moreover, most studies focus on homogeneous networks having nodes with equal transmission radii. At this paper, a probabilistic epidemic (p-epidemic) forwarding scheme is suggested which aims to improve both the energy consumption and the message delivery probability within the heterogeneous sets of nodes. The nodes have two different amounts of available energies and two different transmission radii. Based on this proposed p-epidemic method, the transmission radius and the transmission probability of each node are chosen according to its current energy. The performance of the method is evaluated through many simulations.