Policy

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...

SimUAM: A Comprehensive Microsimulation Toolchain to Evaluate the Impact of Urban Air Mobility in Metropolitan Areas

Yedavalli, Pavan
Burak Onat, Emin
Peng, Xin
Raja Sengupta
Waddell, Paul
Bulusu, Vishwanath
Xue, Min
2021

Over the past several years, Urban Air Mobility (UAM) has galvanized enthusiasm from investors and researchers, marrying expertise in aircraft design, transportation, logistics, artificial intelligence, battery chemistry, and broader policymaking. However, two significant questions remain unexplored: (1) What is the value of UAM in a region’s transportation network?, and (2) How can UAM be effectively deployed to realize and maximize this value to all stakeholders, including riders and local economies? To adequately understand the value proposition of UAM for metropolitan areas, we develop...

Evaluating eVTOL Network Performance and Fleet Dynamics through Simulation-Based Analysis

Onat, Emin Burak
Bulusu, Vishwanath
Chakrabarty, Anjan
Mark Hansen
Raja Sengupta
Sridhar, Banavar
2024

Urban Air Mobility (UAM) represents a promising solution for future transportation. In this study, we introduce VertiSim, an advanced event-driven simulator developed to evaluate e-VTOL transportation networks. Uniquely, VertiSim simultaneously models passenger, aircraft, and energy flows, reflecting the interrelated complexities of UAM systems. We utilized VertiSim to assess 19 operational scenarios serving a daily demand for 2,834 passengers with varying fleet sizes and vertiport distances. The study aims to support stakeholders in making informed decisions about fleet size, network...

A Simulation-Optimization Framework for Developing Wind-Resilient AAM Networks

Onat, Emin Burak
Cao, Shangqing
Rizwan, Raiyan
Jiang, Xuan
Mark Hansen
Raja Sengupta
Chakrabarty, Anjan
2024

Environmental factors pose a significant challenge to the operational efficiency and safety of advanced air mobility (AAM) networks. This paper presents a simulation-optimization framework that dynamically integrates wind variability into AAM operations. We employ a nonlinear charging model within a multi-vertiport environment to optimize fleet size and scheduling. Our framework assesses the impact of wind on operational parameters, providing strategies to enhance the resilience of AAM ecosystems. The results demonstrate that wind conditions exert significant influence on fleet size even...