مدیریت تحرک برای تحویل داده در شبکه های زیرساخت برای خودرو

Efficient and reliable communication between base stations and vehicles is becoming increasingly important for meeting the demands of many intelligent transportation applications. The key challenge here is to deal with constant topological changes in the underlying communication network resulting from vehicular mobility. In this paper, we propose a mobility management scheme MMDD that helps base stations track the location of vehicles registered to their services. Registered vehicles send their location updates to corresponding base stations by following either a distance-based or a time-based mechanism. The location information is subsequently leveraged in transmitting data packets in an efficient and reliable manner. We also propose a paging mechanism through which base stations can obtain the latest location information of any registered vehicle. Through a detailed simulation study, we demonstrate that our location management scheme outperforms a state-of-the-art approach RLSMP, both in terms of average packet delay and success percentage. We also show that the impact of control packets from location update and paging mechanisms on the overall performance is minimal.

Recent research on Intelligent Transportation Systems (ITSs) in Vehicular Networks (VANETs) has focused on providing reliable internet access to vehicles via roadside infrastructure known as base stations. There exist a wide range of applications that require vehicles to access internet services, which include emergency warnings, traffic monitoring, multimedia applications etc. To support ITS applications in VANETs, mobility management techniques that help base stations aware of up-to-date vehicle location information are critical. In this article, we consider the node mobility related issues in Infrastructure-to-Vehicle (I2V) communication where base stations send packets to vehicles. Vehicles make use of control packets to communicate their location information to base stations so that the packets can be sent to vehicles in a reliable and efficient manner. The main challenge is to strike a good balance between vehicle location accuracy and communication overhead due to control packets. Strategies for mobility management in vehicular networks can be classified into three main categories: location management; handoff management; and topology management [1]. Location management techniques allow base stations to maintain last known vehicle locations in a database. Base stations make use of vehicle information to track the current position of vehicles, and leverage them for effective packet delivery. Handoff management is concerned with issues related to maintenance of active connections with base stations as the vehicles change their location. Finally, techniques related to topology management aim to provide effective routing mechanisms in the presence of constant topological changes in the underlying communication network. The topology management and data delivery process are useful for designing routing and MAC protocols. There exist several position-based protocols [2], [3] and [4] that allow vehicles to make adaptive routing decisions as the vehicles move around in the network. These sophisticated methods work well for communication from vehicles to base stations. They, however, are not applicable for communication from base stations to vehicles since the vehicle location information maintained at different base stations is only approximate. In this paper, we propose a Mobility Management scheme for effective Data Delivery (MMDD) in vehicular networks. It is a location management technique that improves the data transmission between base stations and vehicles in I2V systems through multi-hop communication. While such techniques have been developed in the context of cellular networks [5] and [6], they are not readily applicable for VANETs because the structure and organization of communication is quite different from that in cellular systems. Communication in cellular networks is strictly between nodes and base stations. Point-to-point communication among vehicles without involving base stations is not feasible. Therefore, the service area in cellular networks is typically divided into regular shaped cells where each cell is served by a different base station. The communication between vehicles and base stations in MMDD consists of four main processes: service advertisement; registration; location update; and data delivery. Service advertisement allows base stations to broadcast their information within their service area. Unlike in cellular networks, a base station can serve vehicles that are located outside its immediate service area by leveraging the multi-hop communication among vehicles. Therefore, vehicles can simultaneously have access to multiple base stations, and they determine the best available station to obtain internet services via registration process. Vehicles update the registered base station with their position information during the process of location update. We study two schemes for vehicle location update – time-based and distance-based. The location information available at base stations is finally leveraged for effective data packet delivery. Through a detailed simulation analysis, we show that MMDD provides efficiency and reliability in delivering data packets from base stations to vehicles. Remainder of this article is organized as follows. We first discuss the related works in Section 2. We then present an overview of the proposed system MMDD in Section 3. Section 4 describes the details of different processes in MMDD. We finally present the simulation analysis in Section 5, and conclude in Section 6.

We proposed a mobility management scheme called MMDD that aims to provide efficient and reliable I2V communication between base stations and vehicles. By registering to the best available base station, vehicles constantly send their location updates to base stations. The location information is subsequently used by the base stations in effectively transmitting the data packets. We studied two different mechanisms in which location updates can be sent: time-based and distance-base approaches. We also proposed a paging mechanism that is employed prior to sending data packets, and is used to find the latest location of the destination vehicle. Through a detailed simulation study, we showed that our MMDD approach is light-weight in terms of control packet overhead and it outperforms state-of-the-art approach RLSMP, both in terms of delay performance and success rate. In the future, we plan to evaluate our approach by considering a more realistic traffic mobility model and road network topology.