Safety

Medium Access Control Protocol Design for Vehicle-Vehicle Safety Messages

Xu, Qing
Mak, Tony
Ko, Jeff
Raja Sengupta
2005

We propose a Medium Access Control (MAC) protocol design for a vehicle to send safety messages to other vehicles. We develop a QoS model for safety messages consistent with the active safety systems literature. Each message has a range and useful lifetime. The QoS target is to have each message be received with high probability within its specified lifetime by each vehicle within its specified range. The protocol design is based on rapidly re-broadcasting each message multiple times within its lifetime in combination with the 802.11 DCF. This makes the design compatible with the emerging...

Multi-Channel Medium Access Control for Dedicated Short Range Communications

Mak, Tony K.
Laberteaux, Kenneth P.
Raja Sengupta
Ergen, Mustafa
2006

This paper describes a medium access control (MAC) protocol to enable multi-channel operation for dedicated short range communication (DSRC). In particular, we focus on the challenge of supporting potentially high-bandwidth commercial or info-tainment communications between vehicle and roadside in hotspots over several service channels, while concurrently enabling time-critical vehicle-vehicle communication for safety in a separate channel. In our architecture, within hotspots, communication is aided by one of the access points in the hotspot. This access point is designated the...

Cooperative Collision Warning Systems: Concept Definition and Experimental Implementation

Raja Sengupta
Rezaei, Shahram
Shladover, Steven E.
Cody, Delphine
Dickey, Susan
Krishnan, Hariharan
2006

The concept of cooperative collision warning (CCW) systems is introduced and explained, followed by presentation of experimental results showing the performance of a first prototype CCW system. The CCW concept provides warnings or situation awareness displays to drivers based on information about the motions of neighboring vehicles obtained by wireless communications from those vehicles, without use of any ranging sensors. This has the advantages of a potentially inexpensive complement of onboard vehicle equipment (compared to ranging sensors that could provide 360 degree coverage), as...

Lower and Upper Bounds for a Multiple Depot UAV Routing Problem

Rathinam, Sivakumar
Raja Sengupta
2006

This paper extends the well known Held-Karp's lower bound available for a single travelling salesman problem to the following multiple depot UAV routing problem (MDURP): Given a collection of UAVs that start at different depots, a set of terminals and destinations, the problem is to choose paths for each of the UAVs so that (1) each UAV starts at its respective depot, visits atleast one destination and reaches any one of the terminals not visited by other UAVs; (2) each destination is visited by exactly one UAV; and (3) the cost of the paths is a minimum among all possible paths for the...

Medium Access Control Protocol Design for Vehicle–Vehicle Safety Messages

Xu, Qing
Mak, Tony
Ko, Jeff
Raja Sengupta
2007

We propose a medium access control protocol design for a vehicle to send safety messages to other vehicles. We develop a Quality-of-Service (QoS) model for safety messages that are consistent with the active vehicle safety systems literature. Each message has a range and useful lifetime. The QoS target has each message received with high probability within its specified lifetime by each vehicle within its specified range. The protocol design is based on rapidly rebroadcasting each message multiple times within its lifetime in combination with the 802.11 Distributed Coordination Function....

A Feedback-Based Power Control Algorithm Design for VANET

Guan, Xu
Raja Sengupta
Krishnan, Hariharan
Bai, Fan
2007

We consider the problem of adjusting transmission power for vehicle-to-vehicle broadcast safety communication in vehicular ad hoc networks. Given a target communication range designated by a vehicle safety application, the power control algorithm is designed to select a transmission power no greater than necessary for the targeted range. The power control algorithm results in higher communication reliability since collisions are minimized for safety communications. Our main idea is to add a power tuning feedback beacon during each safety message exchange. Our simulation results show that...

3/2-Approximation Algorithm for a Generalized, Multiple Depot, Hamiltonian Path Problem

Rathinam, Sivakumar
Raja Sengupta
2007

We consider a Generalized, Multiple Depot Hamiltonian Path Problem (GMDHPP) and show that it has an algorithm with an approximation ratio of 3/2 if the costs are symmetric and satisfy the triangle inequality. This improves on the 2-approximation algorithm already available for the same.

Adaptive Communication Scheme for Cooperative Active Safety System

Rezaei, Shahram
Raja Sengupta
Krishnan, Hariharan
Guan, Xu
2008

This paper presents an adaptive communication scheme for Cooperative Active Safety System (CASS). CASS uses information communicated from neighboring vehicles via wireless communication in order to actively evaluate driving situations and provide warnings or other forms of assistance to drivers. In CASS, vehicles are equipped with a GPS receiver, a Dedicated Short Range Communications (DSRC) transceiver, and in-vehicle sensors. The information exchanges between vehicles include position, speed, heading, and other vehicle kinematic and dynamic information, and the information is broadcast...

Middleware: Leveraging Mobile Communications for Road Safety and Congestion Relief

Manasseh, Christian
Raja Sengupta
2008

Middleware has emerged as an important architectural component in supporting distributed applications. The role of middleware is to present a unified programming model to application writers and to mask out problems of heterogeneity and distribution. This paper is motivated by the convergence of the embedded sensor and mobile communication revolutions in the automobile. The national vehicle fleet is morphing into a vast mobile sensor fleet. In this paper, we provide a middleware architecture and implementation that addresses the needs of a distributed system of mobile sensors comprised of...

Decentralized Error-Dependent Transmission Control for Model-Based Estimation Over a Multi-Access Network

Huang, Ching-Ling
Raja Sengupta
2008

This paper is motivated by the estimation problem and active safety design for ITS. We investigate the performance of model-based estimation over a multi-access network and emphasizes on asymptotic time-averaged MSE while using error-dependent transmission control. The performance of this decentralized policy is analyzed and an improved policy is also proposed to achieve robustness in a shared channel. Our results suggest that, while designing communication logic for vehicular safety applications, dynamics of the system and channel congestion should be considered at the same time.