Centralized Adaptive Routing in Multihop Cellular D2D Communications

In cellular communication system, a user can com-municate with another user only by using the services of base station (BS) as a relay for forwarding the data. D2D communication is a new paradigm in cellular communication system that enables users to directly exchange data with each other without passing data to the BS. However in D2D communication, when two users which are not in vicinity of each other want to communicate, a multihop D2D route is required. In this work, we take advantage of the presence of BS for establishing such D2D route. We propose a novel route discovery mechanism in which the route decision is the responsibility of BS for a given cell. The route is updated periodically or on-demand depending upon network node density, traffic load and average node mobility. The centralized routing strategy in comparison to distributed routing reduces the routing overhead by avoiding the flooding of route requests. Our novel adaptive mechanism takes benefit from the reactive and proactive schemes and switches the routing strategy between the two, in order to further reduce the routing overhead. Energy awareness, load awareness, special route request packets and earlier stop messages have been seamlessly integrated into our proposed scheme in order to reduce the routing overhead to a dramatic level.