Enabling traffic control and data dissemination applications with VGrid - a vehicular ad hoc distributed computing framework.

摘要

The recent introduction and allocation of the 5.85-5.92 GHz portion of spectrum for inter-vehicle communication (IVC) and vehicle-to-roadside communications (VRC), also referred to as Dedicated Short Range Communications (DSRC)/Wireless Access to Vehicular Environments (WAVE), has generated significant interest in research and development in the field of Vehicular Adhoc Networks (VANETs). There are significant opportunities for research advancements in the fields as well as development and deployment of real VANET applications. The later includes driver-vehicle safety applications, information and entertainment (infotainment) applications, and delivery of Internet services for passengers in vehicles. Although VANET falls under the broader category of Mobile Ad Hoc Networks (MANETs), the VANET environment embodies significant differences from that of traditional MANETs. Unlike many MANETs, a VANET is not constrained by power and computing limitations, as is the case with most wireless hand-held and sensor devices. Vehicles can be equipped computing capabilities and have unconstrained battery power supply. On the other hand, the high velocity of vehicles in a VANET results in highly dynamic channel conditions and unstable network topologies.;As part of this work, we have explored four general research directions in the area of VANET. We begin by introducing and discussing the concept of Vehicular Grid Networks (VGrid) in which wireless networking enabled vehicles equipped with processing and storage capabilities can form an ad hoc distributed computing platform to support novel distributed vehicular applications. In order to conduct VGrid research, we have developed the VGrid simulation tool that accurately simulates the VANET environment and the VGrid framework. Based on the simulation tool we have explored new VGrid applications. These applications can be categorized as (1) vehicular traffic control and safety applications, and (2) infotainment applications, specifically a peer-2-peer (P2P) distributed file sharing applications and the associated resource management issue. Finally, we discuss the performance of the Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP) in a VANET and explore how tuning transmission power affects the performance of these transport protocols.;One of the key application of VGrid is in vehicular safety and control applications. In this research, we investigate the benefits of the ad hoc distributed computing platform of VGrid to enhance the performance of some of these applications. In particular, we investigate the effects of a distributed traffic control system on traffic throughput in a highway scenario. We leverage VGrid and demonstrate how a distributed Variable Speed Limit (VSL) and an accident alert application can smooth traffic flow and increase vehicle throughput in such a system. We also explore a distributed Automated Incident Detection (AID) application which is capable of detecting lane obstruction on a highway. We study how the VGrid framework can be leveraged to build traffic flow patterns which can be analyzed in a distributed manner for anomaly detection to detect lane obstructions. Through detailed simulation analysis using the simulation tool we show that this distributed algorithm performs better then current AID systems.;Besides distributed traffic safety and control applications, is an extremely useful and important direction of research, we also investigate infotainment application in a VANET environment. In particular, we investigate a purely distributed P2P file sharing application. A key aspect in such a system is the resource sharing scheme from each peer which guarantees a certain level of resource availability in both a centralized and distributed P2P system. We present a simple contract scheme in which each peer agrees to share some amount of local resource for the services (files) provided by the P2P system. We show how this contract can be determined both in a centralized and distributed control P2P network. This work provides a framework for developing P2P applications in VGrid.;Due to the inherent dynamic nature of the topology and the link quality in a VANET, the performance of the communication protocols, in particular the transport protocols, is a key factor. Therefore, we also study the performance of both UDP and TCP protocols in the VANET environment. We analyze the performance of TCP and UDP in a multi-lane highway environment where vehicles are configured as clients or routers trying to reach a fixed access point along the highway. In particular, we investigate the effect of tuning transmission power in dense and sparse road scenarios on the TCP and UDP throughput and latency.;While VANET has been studied quite extensively, the proposed ad hoc distributed computing framework in VGrid is a novel paradigm for new class of VANET applications. In this research, we have demonstrated the capability of VGrid in implementing distributed vehicular traffic control and safety applications. VGrid can complement and supplement exiting centralized control system by significantly improving their performance in a cost-effective manner.