Research On Routing Protocol In Vehicular Ad Hoc Networks

As one of the key research techniques in network structure, routing protocol has been received widely attention by the researchers from universities, research organizations. Vehicular ad hoc networks (VANETs) are an important component of the intelligent transportation system, which are also widely concerned. The performance of routing protocol directly decides the utility of VANETs. Many unique characteristics of Vehicular ad hoc networks (i.e. dynamic network topology and frequent network fracture) bring great challenges to the data dissemination and routing. In fact, rapid changing topology and frequent network fracture make it difficult to design an efficient routing algorithm for vehicular networks. Routing protocol of traditional wireless sensor network and mobile ad-hoc network cannot be applied in the VANETs. Therefore, it is very important to take consideration in network characteristics for routing protocol research. This paper focuses on the routing protocol in VANETs and analyzes the deficiency of the existing algorithms. After that, it designs a new routing algorithm which makes full use of some inherent characteristics in VANETs.The efficiency and stability of the route are usually taken into consideration separately. As a consequence, overall performance of routing protocol is not comparatively high. This paper proposes a Moderate Routing Protocol (MRP), which is capable of finding efficient and stable routes within urban environments. The main principle of MRP is the novel metric presented to tradeoff the hop counts and link stability within the multihop paths. This algorithm firstly divides the real traffic network into intersection areas and sections between two junctions, then establish connection and distance model (CDM). When a source node needs to send information to a destination, MRP protocol finds a routing path hop-by-hop. Since we know the connectivity and distance model for each road segment and intersection, the next hop of a certain node can be selected through a new approach, whose CDP value is the greatest among the candidate neighboring nodes. The next hop of a node whose position is in segment can be directly selected among its neighbors. When the routing path disconnect, routing recovery mode is launched. If the forwarding node has no one-hop neighbor, it will carry the packet until another node within its transmission range is better to transfer the packet. The MRP protocol fully takes advantage of the unique characteristics of vehicular moving environment, like distance between the vehicles, street layout and transmission range, which makes the vehicle and its neighbors traveling in the line, in obtaining stability and efficient routing path through making routing and forwarding decisions.Since the MRP protocol needs to know neighbors’information when it calculates the value of CDP function. Whenever the number of neighbor nodes is different, using the same strategy to exchange information wastes more time. Combined with the number of neighbor nodes, MRP protocol and802.11DCF, it puts forward an advanced algorithm of MRP. Our solution is an adaptive next-hop election scheme. It means that when a node whose number of neighbors is great will choose a distributed next-hop election method, and when a node whose number of neighbors is low will choose a centralized next-hop election method. The improved scheme optimizes the overall performance of routing protocol.Finally, to evaluate the performance of our proposed approach MPR, we simulate the algorithm on a variety of density and data rate. Numerical simulations show that the proposed moderate routing protocol performs significant better than the existing routing protocols in VANETs.