Gavin D. Holland

Cooperative collision warning using dedicated short range wireless communications

The emergence of the 802.11a-based Dedicated Short Range Communications (DSRC) standard and advances in mobile ad hoc networking create ample opportunity for supporting delay-critical vehicular safety applications in a secure, resource-efficient, and reliable manner. In this paper, we focus on the suitability of DSRC for a class of vehicular safety applications called Cooperative Collision Warning (CCW), where vehicles periodically broadcast short messages for the purposes of driver situational awareness and warning. First, we present latency and success probability results of Forward Collision Warning (FCW) applications over DSRC. Second, we explore two design issues that are highly relevant to CCW applications, namely performance trends with distance and potential avenues for broadcast enhancements. Simulation results reveal interesting insights and trade-offs related to application-perceived latency and packet success probability performance. For instance, we conjecture the existence of an optimal broadcast rate that minimizes our novel latency measure for safety applications, and we characterize it for plausible scenarios.

Towards characterising and classifying communication-based automotive applications from a wireless networking perspective

Together, the Dedicated Short Range Communication (DSRC) and Vehicular Ad Hoc Network (VANET) technologies provide a unique opportunity to develop and introduce various types of communication- based automotive technologies to the marketplace. To date, many applications have been identified by the automotive community. Given the large number and diverse nature of these applications, it is advantageous to develop a systematic classification methodology to facilitate future DSRC and VANET research. Toward this objective, in this paper, we present a study that goes through two major steps: characterisation and classification. First, we focus on a set of representative applications and characterise them with respect to plausible application- and networking-related attributes. The characterisation process not only strengthens our understanding of the applications but also sets the stage for the classification step since it reveals numerous application commonalities. Thus, we have categorised the given applications into seven generic classes, with the consideration of balancing the trade-off between exploiting as many application similarities as possible while preserving their salient differences. This is of paramount importance to facilitate performance analysis of newly designed protocols. Finally, we have identified key performance metrics for each class of applications, which, we hope, could bridge the gap between the automotive and wireless networking communities. Accordingly, the proposed classes are envisioned to play a dual-role: facilitate application simulation and performance evaluation and guide DSRC and VANET protocol research and development.

DSRC Channel Fading Analysis from Empirical Measurement

Vehicle-to-vehicle communication research has gained tremendous interest in recent years due to its importance in facilitating future active safety and telematics applications. However, with limited literature available, there is lack of understanding for modeling mobile-to-mobile channels in vehicular environments. In this paper, we conduct preliminary channel fading statistical analysis of empirical measurement data from devices compatible with the emerging dedicated short range communications (DSRC) standard. In particular, we use the Nakagami distribution to analyze the received signal strength (i.e., RSSI) from empirical measurement, and characterize the fading statistics as a function of distance for vehicular operating environment. Our analysis reveals that fading can be approximated by Rician distribution within 100 m while it seems to follow Rayleigh distribution beyond 100 m. The outcome of the study could be used for vehicular network simulation.

Secure and privacy-preserving querying of content in MANETs

Ensuring security and privacy of content in a mobile ad-hoc network (MANET) is a challenging problem, especially when that content is distributed over the network using some form of peer-to-peer dissemination scheme. Since cooperation among nodes is vital in MANETs, the capture or compromise of a single node not only exposes locally cached content, but also allows an adversary to interrogate the network with the authority of an insider, acquiring important information such as content access patterns, popularity and location. Previous work in MANETs has predominantly focused on providing solutions for security and anonymity of routing protocols, confidentiality, and key management. In this paper, we present protocols that provide the ability to securely and privately locate content for two common peer-to-peer dissemination operations: publish/subscribe (content PUSH), and direct query (content PULL).