AN APPROACH FOR DYNAMIC REPLICA ALLOCATION FOR SPARSE (URBAN/SUB-URBAN) AND DENSE REGIONS (CITY SIDE) IN VANET

It is important to determine the place for erecting communication devices such as access points and wireless routers alongside the road to offer communication services to vehicles moving on the road. The vehicle density varies largely in the city areas, urban and sub urban areas. VANET (Vehicular Ad hoc Network) consists of vehicles moving with a high velocity on either direction of road, making them to communicate with each other to exchange safety messages and share other information, useful for the safety of passenger and driver. Vehicle also exchanges data that belongs to infotainment applications such as video streaming. High mobility of vehicles causes frequent path disconnections between them, due to which the data being accessed becomes unavailable. Replication is one of the popular techniques to increase data availability among nodes in any network by making them available at many nodes other than the originating node. While replication increases the data availability, it also adds to the cost of replication which may deteriorate the performance of the system. Since VANET has varying density of vehicles in city and highway locations we decide the number of replicas for dense and sparse region dynamically based on the density of vehicles in both. It is necessary to keep less number of replicas in city region as there is going to be less path disconnection with large numbers of vehicle, whereas highway situation may require more number of replica nodes since it may encounter frequent path disconnections. We propose an algorithm to allocate replica dynamically in this way and prove the benefits obtained in terms of replication cost.