Road-based routing in vehicular ad hoc networks

Vehicular ad hoc networks (VANETs) can provide scalable and cost-effective solutions for applications such as traffic safety, dynamic route planning, and context-aware advertisement using short-range wireless communication. To function properly, these applications require efficient routing protocols. However, existing mobile ad hoc network routing and forwarding approaches have limited performance in VANETs. This dissertation shows that routing protocols which account for VANET-specific characteristics in their designs, such as high density and constrained mobility, can provide good performance for a large spectrum of applications. This work proposes a novel class of routing protocols as well as three forwarding optimizations for VANETs. The Road-Based using Vehicular Traffic (RBVT) routing is a novel class of routing protocols for VANETs. RBVT protocols leverage real-time vehicular traffic information to create stable road-based paths consisting of successions of road intersections that have, with high probability, network connectivity among them. Evaluations of RBVT protocols working in conjunction with geographical forwarding show delivery rate increases as much as 40% and delay decreases as much as 85% when compared with existing protocols. Three optimizations are proposed to increase forwarding performance. First, one- hop geographical forwarding is improved using a distributed receiver-based election of next hops, which leads to as much as 3 times higher delivery rates in highly congested networks. Second, theoretical analysis and simulation results demonstrate that the delay in highly congested networks can be reduced by half by switching from traditional FIFO with Taildrop queuing to LIFO with Frontdrop queuing. Third, nodes can determine suitable times to transmit data across RBVT paths or proactively replace routes before they break using analytical models that accurately predict the expected road-based path durations in VANETs

Cooperative & cost-effective network selection: a novel approach to support location-dependent & context-aware service migration in VANETs

Vehicular networking has gained considerable interest within the research community and industry. This class of mobile ad hoc network expects to play a vital role in the design and deployment of intelligent transportation systems. The research community expects to launch several innovative applications over Vehicular Ad hoc Networks (VANETs). The automotive industry is supporting the notion of pervasive connectivity by agreeing to equip vehicles with devices required for vehicular ad hoc networking. Equipped with these devices, mobile nodes in VANETs are capable of hosting many types of applications as services for other nodes in the network. These applications or services are classified as safety-critical (failure or unavailability of which may lead to a life threat) and non-safety-critical (failure of which do not lead to a life threat). Safety-critical and non-safety-critical applications need to be supported concurrently within VANETs. This research covers non-safety-critical applications since the research community has overlooked this class of applications. More specifically, this research focuses on VANETs services that are location-dependent. Due to high speed mobility, VANETs are prone to intermittent network connectivity. It is therefore envisioned that location-dependence and intermittent network connectivity are the two major challenges for VANETs to host and operate non-safety-critical VANETs services. The challenges are further exacerbated when the area where the services are to be deployed is unplanned i.e. lacks communication infrastructure and planning. Unplanned areas show irregular vehicular traffic on the road. Either network traffic flows produced by irregular vehicular traffic may lead to VANETs communication channel congestion, or it may leave the communication channel under-utilized. In both cases, this leads to communication bottlenecks within VANETs. This dissertation investigates the shortcomings of location-dependence, intermittent network connectivity and irregular network traffic flows and addresses them by exploiting location-dependent service migration over an integrated network in an efficient and cost-effective manner