Policy

Safety and Capacity Analysis of Automated and Manual Highway Systems

Carbaugh, Jason
Godbole, Datta N.
Raja Sengupta
1999

This paper compares safety of automated and manual highway systems with respect to result- ing rear-end collision frequency and severity. The results show that automated driving is safer than the most alert manual drivers, at similar speeds and capacities. We also present a detailed safety-capacity tradeo study for four di erent Automated Highway System concepts that di er in their information structure and separation policy.

WTRP - Wireless Token Ring Protocol

Ergen, M.
Lee, Duke
Raja Sengupta
Varaiya, P.
2004

The wireless token ring protocol (WTRP) is a novel medium access control (MAC) protocol for wireless local area networks (WLANs). In contrast with IEEE 802.11 networks, WTRP guarantees quality of service (QoS) in terms of bounded latency and reserved bandwidth, which are critical in many real-time applications. Compared to 802.11, WTRP improves efficiency by reducing the number of retransmissions due to collisions, and it is more fair as all stations use the channel for the same amount of time. Stations take turns transmitting and give up the right to transmit after a specified amount of...

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

Xu, Qing
Raja Sengupta
2005

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...

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.

Stability Bounds on Entropy Rate for Real-Time Tracking an Unstable LTI Process Over a Multi-Access Network

Huang, Ching-Ling
Raja Sengupta
2009

We assume the separation of source/channel coding and propose a framework for real-time tracking an unstable, scalar, linear time-invariant (LTI) process via a G/G/1- queueing network. We derive a stability bound on the entropy rate of an unstable LTI process such that tracking error can stay bounded for specified moment. This bound is a function of the moment to be stabilized, encoder efficiency, quantization accuracy, and network parameters. This bound is sufficient under all load conditions and tight when the network is heavily utilized. Proposed framework covers a broad class of...

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...

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...

Stability of Dynamic Traveling Repairman Problem Under Polling-Sequencing Policies

Huang, Jiangchuan
Raja Sengupta
2013

We establish a necessary and sufficient condition for stability in the dynamic traveling repairman problem (DTRP) [3] under the class of polling-sequencing (P-S) policies satisfying unlimited-polling and economy of scale. The P-S class includes some of the policies proven to be optimal for the expectation of system time under light and heavy loads in the DTRP literature. The number of tasks inside each polling partition is shown to be a Markov chain. Policies such as first come first serve, traveling salesman policy, nearest neighbor and Daganzo's algorithm are shown to have economy of...

System Time Distribution of Dynamic Traveling Repairman Problem Under the PART-n-TSP Policy

Huang, Jiangchuan
Raja Sengupta
2015

We propose the PART-n-TSP policy for the Dynamic Traveling Repairman Problem [1]. We compute a good approximation for the distribution of the system time, defined as the elapsed time between the arrival and the completion of each task. PART-n-TSP stabilizes the system for every load in [0; 1). PART-n-TSP has lower system time variance than PARTTSP [14] and Nearest Neighbor [1] when the load is neither too small or too large. We show that PART-n-TSP is also optimal for system time expectation under light and heavy loads.

Quantified Traveler: Travel Feedback Meets the Cloud to Change Behavior

Raja Sengupta
Joan Walker
2015

Halting climate change will require a concerted effort to reduce emissions from on-road vehicles. While significant progress has been made to improve vehicle efficiency and reduce CO 2 emissions, surface transportation accounted for half the increase in US green-house gas (GHG) emissions over the past two decades. Today, surface transportation accounts for 24 percent of all US emissions. Automobile improvements alone will not be sufficient to meet federal and state emissions targets; policy makers also need to identify solutions that reduce the demand for car travel. Information technology...