###### Abstract  
Vehicular ad hoc networks (VANETs) have emerged as a new powerful technology for data transmission between vehicles. Efficient data transmission accompanied with low data delay plays an important role in selecting the ideal data forwarding path in VANETs. This paper proposes a new opportunity routing protocol for data forwarding based on vehicle mobility association (OVMA). With assistance from the vehicle mobility association, data can be forwarded without passing through many extra intermediate nodes. Besides, each vehicle carries the only replica information to record its associated vehicle information, so the routing decision can adapt to the vehicle densities. Simulation results show that the OVMA protocol can extend the network lifetime, improve the performance of data delivery ratio, and reduce the data delay and routing overhead when compared to the other well-known routing protocols. VANETs; opportunistic routing; vehicle association; data forwarding +
Footnote †: journal: Information  
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-vehicular environment (WAVE) inside the vehicle. On the other hand, cellular system communication technologies such as General Packet Radio Service (GPRS), Enhanced Data Rate for GSM Evolution (EDGE), 3G, and Long Term Evolution (LTE) [2]. Alerting drivers about traffic and road conditions, and other related aspects are essential to safety [3]. To accomplish this, timely and accurate information delivery is crucial. The typical problems of VANETs are shown in Figure 1. Emergencies can be prevented by exploiting the instruments supplied by VANETs technologies--in other words, all information related to vehicle mobility, such as speed, the direction of vehicles' travel, vehicle density, etc., which are gathered by using Vehicle-to-Vehicle (V2V), Vehicle-to-Infrastructure (V2I) [4], and other communication technologies. That information helps to organize road traffic and prevent accidents. The three the most common vehicle communication technologies are V2V, V2I [4], and dedicated short range communications (DSRC). For Vehicle-to-Vehicle (V2V),a number of wireless transmission technologies can be realized in the physical layer. Examples include IEEE802.11 [5], 3G, WiMax [6], etc. IEEE802.11 is an appropriate technology to provide the wireless connection in VANETs due to its deployment cost, delivery data rate, and service fees [7]. However, due to the high mobility and the limited transmission range from the antenna, handoff is frequent in VANETs. The main challenge of these kinds of vehicles for applications is in finding a way to maintain a persistent connection with the vehicle in order to deliver data from source to destination via wireless transmission or storage-carry-forward techniques. The design of effective data forward methods is crucial in the development of this technology. Accordingly, some research work has recently been conducted on this topic. Among the existing methods, some studies are concerned with selecting a candidate intersection to forward data regarding the density of vehicles off the road, using a method such as vehicle-assisted data delivery (VADD) [8]. However, not only the vehicle density but also the association degree of vehicles can affect the vehicles' connectivity. This paper focuses on how to achieve fast data forwarding and transmission in the case of low latency and low routing overhead. In this study, the proposed algorithm: An Opportunistic Routing for Data Forwarding Based on Vehicle Mobility Association (OVMA) using the vehicle mobility association can find an optimal path to deliver data from the source vehicle to the destination vehicle, without having to pass through many unwanted intermediate vehicleswith a low degree of association. Figure 1: Generalized architecture in vehicular ad hoc networks (VANETs). OVMA calculates the probability of data transmission between nodes by comparing the association between nodes and chooses the path with the highest probability of data transmission as the optimal data propagation path.