Travel Behavior

Implementation andEevaluation of Scalable Vehicle-to-Vehicle Transmission Control Protocol

Huang, Ching-Ling
Krishnan, Hariharan
Raja Sengupta
Fallah, Yaser P.
2010

Vehicle-to-Vehicle (V2V) communications play a critical role in enabling important cooperative safety applications. V2V safety communications rely on broadcast of self-state information (e.g., position, speed, and heading) by each vehicle, which allows a vehicle to track its neighboring vehicles in real-time. One of the most pressing challenges in this research is to maintain an acceptable tracking accuracy of neighboring vehicles while avoiding congestion in the shared communication channel. In this paper we describe the evaluation of a transmission control protocol that adapts the...

Congestion Control Based on Channel Occupancy in Vehicular Broadcast Networks

Fallah, Yaser P.
Huang, ChingLing
Raja Sengupta
Krishnan, Hariharan
2010

Cooperative vehicle safety (CVS) systems rely on vehicular ad-hoc networks operating in broadcast mode to deliver vehicle tracking and safety information to neighboring cars. This information is used to enable collision avoidance and warning systems. One of the main challenges of the eventual large scale deployment of such systems is network congestion, which could critically degrade the quality of a CVS system. In this paper, we present a method for congestion monitoring and control based on limited feedback from the network. We study the relationship between channel occupancy, as a...

VII California: Development and Deployment Proof of Concept and Group-Enabled Mobility and Safety (GEMS)

Misener, Jim
Raja Sengupta
Ahern, Katherine
Gupta, Somak Datta
Dickey, Susan
Kuhn, Tom
Lian, Thang
Manasseh, Christian
Nelson, David
Rezai, Shahram
Sharafsaleh, Ashkan
Shladover, Steven
VanderWerf, Joel
2010

This PATH Research Report covers the (Vehicle-Infrastructure Integration) VII California Development and Deployment (Task Order6217) efforts beginning in 2008 and concluding June 30, 2009. This is a successor to the report for TO 5217and reports theapplications-oriented research subsequent to that work.The report is organized by a synopsis of the background and reasons for the VII California project, then it summarizes some of the antecedent (TO 5217) work: the "Innovative Mobility Showcase" (2005), which established the architecture and, importantly the applications (curve overspeed...

Analysis of Information Dissemination in Vehicular Ad-Hoc Networks With Application to Cooperative Vehicle Safety Systems

Fallah, Yaser P.
Huang, Ching-Ling
Raja Sengupta
Krishnan, Hariharan
2011

Cooperative vehicle safety systems (CVSSs) rely on vehicular ad-hoc networks (VANETs) for the delivery of critical vehicle tracking information. The wireless channel in such systems is shared by vehicles within the transmission range of each other. Due to the near-linear spatial distribution of vehicles in a highway scenario, the vehicular broadcast network is heavily affected by the hidden node interference phenomenon, which considerably limits its capacity. The performance of vehicle tracking application that is the basis for CVSS is therefore significantly affected by the performance of...

SafeTrip 21 Initiative: Networked Traveler Foresighted Driving Field Experiment Final Report

Nowakowski, Christopher
Gupta, Somak Datta
Raja Sengupta
Mannassehm, Christian
Spring, John
VanderWerf, Joel
Sharafsaleh, Ashkan
Vizzini, Daniel
2011

This report describes the SafeTrip-21, Networked Traveler Foresighted Driving Field Experiment conducted as part of the US DOT’s SafeTrip-21 initiative. This experiment developed and evaluated an Advanced Driver Assistance System providing soft-safety or situational awareness alerts regarding “Slow Traffic Ahead” when driving on a freeway. The Networked Traveler system detects slow traffic or queues at several thousand locations in the Bay area, monitors the locations and speeds of its test subjects as they drive, and determines if the driver is approaching the slow traffic fast enough to...

The Quantified Traveler: Using Personal Travel Data to Promote Sustainable Transport Behavior

Jariyasunant, Jerald
Carrel, Andre
Ekambaram, Venkatesan
Gaker, D. J.
Kote, Thejovardhana
Raja Sengupta
Joan Walker
2011

With the advent of ubiquitous mobile sensing and self-tracking groups, travel demand researchers have a unique opportunity to combine these two developments to improve the state of the art of travel diary collection. While the use of mobile phones and the inference of travel diaries from GPS and sensor data allows for lower-cost, longer surveys, we show how the self-tracking movement can be leveraged to interest people in participating over a longer period of time. By compiling personalized feedback and statistics on participants’ travel habits during the survey, we can provide the...

Real-time Estimation of a Markov Process Over a Noisy Digital Communication Channel

Xu, Qing
Raja Sengupta
2011

We study the real-time estimation of a Markov process over a memoryless noisy digital communication channel. The goal of system design is to minimize the mean squared estimation error. We first show the optimal encoder and decoder can be memoryless in terms of the source symbols. We then prove the optimal encoder separates the real space with hyperplanes. In the case of the binary symmetric channel and scalar source, the optimal encoder can be a threshold. A recursive algorithm is given to jointly find a locally optimal encoder and decoder for the binary symmetric channel. For a memoryless...

Intervehicle Transmission Rate Control for Cooperative Active Safety System

Huang, Ching-Ling
Fallah, Yaser Pourmohammadi
Raja Sengupta
Krishnan, Hariharan
2011

We propose an intervehicle communication framework for the cooperative active safety system (CASS) whose operation is based on the dissemination of each vehicle's state information through a wireless network. Such a CASS requires each subject vehicle to be aware of its surroundings, particularly of the motion and position of other vehicles in its proximity. In this paper, we assume that all vehicles are equipped with onboard communication devices. In such situations, the wireless channel is simultaneously shared by a large number of vehicles, and one of the most difficult challenges in...

Real-Time Tracking of Linear Processes Over an AWGN Channel Without Feedback: The MMSE Optimality of the Innovation Encoder

Huang, Ching-Ling
Raja Sengupta
Huang, Jiangchuan
2011

We first present a formulation for the real-time tracking of a scalar continuous-time linear process over an Additive White Gaussian Noise (AWGN) channel without channel feedback and prove several results for minimum mean-squared error (MMSE) tracking. For the one-to-one channel case, we give an optimal encoder-decoder pair along with the optimal tracking performance. With the Gaussian distributed source innovation, one optimal form of the encoder is shown to be a linear innovation encoder, which scales the source innovation to match with the power constraint of the channel input. We then...

Scaling Laws for Cooperative Node Localization in Non-Line-of-Sight Wireless Networks

Ekambaram, Venkatesan
Ramchandran, Kannan
Raja Sengupta
2011

We study the problem of cooperative node localization in non-line- of-sight (NLOS) wireless networks and address design questions such as, "How many anchors and what fraction of line-of-sight (LOS) measurements are needed to achieve a specified target accuracy?". We analytically characterize the performance improvement in localization accuracy as a function of the number of nodes in the network and the fraction of LOS measurements. In particular, we show that the Cramer- Rao Lower Bound (CRLB) can be expressed as a product of two factors - a scalar function that depends only on the...