Location-demanded Data Delivery over Vehicular Ad hoc Networks Pham Van Tien School of Electronics and Telecommunications Hanoi University of Science and Technology No.1 Dai Co Viet Street, Hanoi, Vietnam Email: tienpv-fet@mail.hut.edu.vn Nguyen Tien Dzung School of Electronics and Telecommunications Hanoi University of Science and Technology No.1 Dai Co Viet Street, Hanoi, Vietnam dungnt-set@mail.hut.edu.vn Bui Duc Viet Vietel R&D, Viettel Group Lac Long Quan str. 380, Haonoi, Vietnam vietbd2@viettel.com.vn Tran Huu Cuong School of Electronics and Telecommunications Hanoi University of Science and Technology No.1 Dai Co Viet Street, Hanoi, Vietnam lightgroup.cuong@gmail.com Abstract—Vehicular ad hoc networks (VANET) have great potentials in modernizing transportation infrastructure. Deployment of data communications over such systems however is challenging due to node mobility. Unlike traditional networking scenarios, a user initiating a session for seeking traffic data (called receiver) is assumed to not know the identity associated with the counterpart. In reality, he or she instead likely issues data request with location description, rather than with identity description. In this sense, our study introduces a new notion of location-demanded session control and data delivery in a tenet of cross-layer design. We also let nodes communicate link quality to figure out the best route for a particular driver to look for an appropriate car who is able to return the traffic data that the receiver wishes. At the same time, we also implemented a route monitoring mechanism to assure an acceptable reliability of data delivery. Both simulations and experimental results demonstrate the feasibility and the soundness of the proposed strategy. Keywords-VANET, location-demanded, session control, and routing. I. INTRODUCTION (HEADING 1) In the recent years, vehicular ad hoc network (VANET) is considered as an efficient way to provide communication means over the road. Being formed of embedded devices associated with moving vehicle, VANET is an extremely dynamic system, challenging deployment of any distributed application. Interactive communication between users (drivers) is hindered by the following network characteristics: • There are many vehicles over the road whose drivers are essentially anonymous to each other. They do not know nor care about identity of one another, making conventional session control protocols inapplicable. • Vehicles normally move fast, making node presence at a road section is almost transient, being no longer than a few minutes, if not seconds. Traditional IP-based multimedia applications like Yahoo Messenger, Skype, etc essentially rely on mapping between user name and IP address to setup voice calls. Users need to know identity of each other before setting up a session. Centralized SIP servers such as registrar, proxy, and redirect ones allow a user to find out the counterpart easily through his or her identity (nickname, email, etc). This fashion apparently does not work in vehicular networks due to the above facts. In VANETs, IP address may be changed as the car moves from one road to another [1]. Secondly, even the network address is statically allocated, the SIP-based mechanism is not appropriate, given that no place would store identity of the whole driver community. Furthermore, no node in the network is able to and willing to act as SIP servers. Investigating literature, we have learnt that there are very few studies addressing the issue of session control in VANETs. All of them follow the identity-oriented model to set up communication sessions. Specifically, distributed SIP variants are proposed in [3][4][6][7]. These protocols basically aim at setting up session by translating between callee’s network address and user identity. Namely, before initiating a session, the caller must know the identity of the callee, for example, its email, nickname, plate number, etc. This fashion is obviously unrealistic in VANETs since drivers basically do not know each other, being unwilling to reveal their own identity. Furthermore, those studies basically only rely on simulations to evaluate their proposed design. Differently, this study initiates a new notion of data fetching data in VANETs. Instead of user identity-oriented session control, we define a location-demanded strategy. In reality, communicated data that drivers wish are usually short messages, voice, scene images and videos [3][7], which are always associated with location of vehicles. The driver on road usually care about the position where data are captured, rather than who creates the data. To be plain, the driver explicitly tells the network system: “please give me the data from a place one kilometer ahead”, rather than “please give me photos captured