Analytical modeling of delay-tolerant data dissemination in vehicular networks

Vehicular networking is an emerging technology to support applications involving communications between vehicles, between vehicles and fixed access points, and between vehicles and the Internet cloud. The goal is to enable vehicles to exchange information for improved safety through situational awareness, enhanced convenience, and achieve increased levels of efficiency in time and energy consumption; all significant societal objectives. Safety messaging, real-time traffic and route updates, traffic monitoring, remote diagnostics, general purpose Internet access and in-car entertainment are examples of applications that are targeted by this technology.;This dissertation considers communication and networking among vehicles that are commonly constrained to navigable roadways. We propose a novel routing technique that incorporates attributed, or labeled, messaging; geographic routing; and delay tolerant networking techniques in a solution that operates in a network characterized by rapid mobility and time-varying partitioning (fragmentation). An analytical model is developed to demonstrate the performance of opportunistic data exchange in a delay tolerant network setting.;Contributions of the work include revelation of phase transition behavior due to vehicle density and transmission range. We are able to identify regimes of density where gains are achieved by exploiting the opportunistic contacts between vehicles traveling in opposing directions in a network characterized by time-varying partitioning. The results, supported by simulation, imply that delay tolerant networking architectures are most useful at traffic densities of 20 vehicles/km and higher. Also significant is the observation that increased mobility of nodes from 0 m/s to 10 m/s yields an order of magnitude increase in the performance of messaging from 0 m/s to 200 m/s. The proposed architecture is compared with existing mobile ad hoc networking schemes and performance gains achieved are provided in detail. It is demonstrated that large access point separations are possible in a hybrid environment with intermittently placed access points supported by multihop networking. The performance is dominated by vehicular traffic density. Under delay tolerant networking assumption, minimum delay and maximum propagation rates are achieved for low vehicular traffic densities of 20 vehicles/km, for given parameters. A path based messaging scheme would achieve similar performance at 40 vehicles/km.