Wenchao Xu

An Efficient PMIPv6-Based Handoff Scheme for Urban Vehicular Networks

In urban vehicular networks, traveling users can enjoy Internet multimedia services through various mobile devices, such as smart phones and laptops. To maintain seamless and ubiquitous Internet connectivity, an efficient handoff scheme has to be employed when mobile users travel across different access networks. However, in the urban vehicular environment, the high velocity of vehicles and the random mobility of users impose great challenges to the design of an effective handoff scheme. In this paper, we propose an Efficient Proxy Mobile IPv6 (E-PMIPv6)-based handoff scheme that guarantees session continuity for urban mobile users. In the registration process, E-PMIPv6 enables mobile users to obtain seamless Internet connectivity either from fixed roadside units or mobile routers and improves cache utilization at the local mobility anchor by merging the binding cache entries of the mobile users. In the handoff process, E-PMIPv6 comprehensively considers various handoff scenarios in the urban vehicular environment and provides transparent network-based mobility support to individual mobile users or a group of users in the same mobile network without disrupting ongoing sessions. In addition, E-PMIPv6 eliminates packet loss by either packet buffering or packet tunneling to improve handoff performance in each handoff scenario. Finally, a detailed analytical model is developed to study the performance of E-PMIPv6 in terms of handoff latency, signaling overhead, buffering cost, and tunneling cost. Analysis and simulation results demonstrate that the proposed E-PMIPv6 successfully extends the scalability of user mobility and greatly improves handoff efficiency in urban vehicular networks.

Service-Oriented Dynamic Connection Management for Software-Defined Internet of Vehicles

Internet of vehicles (IoV) is an emerging paradigm for accommodating the requirements of future intelligent transportation systems (ITSs) with the overwhelming trend of equipping vehicles with versatile sensors and communications modules, and facilitating drivers and passengers with a variety of innovative ITS applications. However, the implementation of IoV still faces many challenges, such as flexible and efficient connections, quality of service guarantee, and multiple concurrent support requests. To this end, in this paper we introduce the software-defined IoV (SD-IoV), which is able to tackle the above-mentioned issues by adopting the software-defined networking framework. We first present the architecture of SD-IoV and develop a centralized vehicular connection management approach. Then, we aim to allocate dedicated communications resources and underlying vehicular nodes to satisfy each service. We formulate the dynamic vehicular connection as an overlay vehicular network creation (OVNC) problem. A comprehensive utility function is also designed to serve as the optimization objective of OVNC. Finally, we solve the OVNC problem by developing a graph-based genetic algorithm and a heuristic algorithm, respectively. Extensive simulation results are provided to demonstrate the effectiveness of our proposed solution of dynamic vehicular connection management.

Internet of vehicles in big data era

As the rapid development of automotive telematics, modern vehicles are expected to be connected through heterogeneous radio access technologies and are able to exchange massive information with their surrounding environment. By significantly expanding the network scale and conducting both real time and long term information processing, the traditional Vehicular Ad- Hoc Networks U+0028 VANETs U+0029 are evolving to the Internet of Vehicles U+0028 IoV U+0029, which promises efficient and intelligent prospect for the future transportation system. On the other hand, vehicles are not only consuming but also generating a huge amount and enormous types of data, which are referred to as Big Data. In this article, we first investigate the relationship between IoV and big data in vehicular environment, mainly on how IoV supports the transmission, storage, computing of the big data, and in return how IoV benefits from big data in terms of IoV characterization, performance evaluation and big data assisted communication protocol design. We then investigate the application of IoV big data for autonomous vehicles. Finally the emerging issues of the big data enabled IoV are discussed.

SS-MAC: A Novel Time Slot-Sharing MAC for Safety Messages Broadcasting in VANETs

Efficient and scalable media access control (MAC) protocol design is crucial to guarantee the reliable broadcast of safety messages in vehicular ad hoc networks. To devise a MAC for safety message broadcasting with reliability and minimum delay, in this paper, we propose a novel time slot-sharing MAC, referred to as SS-MAC, which can support diverse periodical broadcasting rates. In specific, we first introduce a circular recording queue to online perceive time slot occupying status. We then design a distributed time slot sharing (DTSS) algorithm and random index first fit (RIFF) algorithm, to efficiently share the time slot and make the online vehicle-slot matching, respectively. We prove theoretically the efficacy of DTSS algorithm, and evaluate the efficiency of RIFF algorithm by using MATLAB simulations. Finally, we conduct extensive simulations considering various driving scenarios and resource conditions to demonstrate the SS-MAC performance.

Drone Assisted Vehicular Networks: Architecture, Challenges and Opportunities

This article introduces the DAVN, which provides ubiquitous connections for vehicles by efficiently integrating the communication and networking technologies of drones and connected vehicles. Specifically, we first propose a comprehensive architecture of the DAVN and outline its potential services. By cooperating with vehicles and infrastructures, drones can improve vehicle-to-vehicle connectivity, infrastructure coverage, network information collection ability, and network interworking efficiency. We then present the challenges and research opportunities of DAVNs. In addition, a case study is provided to demonstrate the effectiveness of DAVNs by leveraging our designed simulation platform. Simulation results demonstrate that the performance of vehicular networks can be significantly enhanced with the proposed DAVN architecture.

Ti-Fi: Terminal-to-terminal communication incorporated Wi-Fi offloading

Wi-Fi is a cost-effective way to offload the increasing data traffic from cellular networks. However, users can only associate to one access point (AP) at a time, which limits the offloading performance in multiple hotspots scenario. In order to enhance the offloading performance and improve the utilization of Wi-Fi capacity as well, we propose a terminal-to-terminal (T2T) communication incorporated Wi-Fi offloading (Ti-Fi), where two neighboring users can assist each other to offload data via T2T communication and their Wi-Fi connections. We analyze the proposed Ti-Fi scheme by employing the M/G/1/K queueing model and evaluate the offloading performance. We show that the T2T communication can improve the Wi-Fi offloading efficiency by up to 21% and reduce the cellular traffic by up to 80% with very short extra delay. The results in this paper provide important guidelines on efficiently deploying Wi-Fi networks and choosing T2T pairs to improve the offloading performance.