Klara Nahrstedt

Prof. Klara Nahrstedt

University of Illinois at Urbana Champaign

Research Focus & Metrics

Academic Career Length

25Years (2002-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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16 August 2018 in IEEE/ACM Transactions on Networking
Verified
Journal Article
Closed access
HJHaiming Jin
Haiming Jin
LSLu Su
Lu Su
HXHouping Xiao
Houping Xiao
Klara NahrstedtKlara Nahrstedt
Klara Nahrstedt
The recent proliferation of human-carried mobile devices has given rise to mobile crowd sensing (MCS) systems that outsource the collection of sensory data to the public crowd equipped with various mobile devices. A fundamental issue in such systems is to effectively incentivize worker participation. However, instead of being an isolated module, the incentive mechanism usually interacts with other components which may affect its performance, such as data aggregation component that aggregates workers’ data and data perturbation component that protects workers’ privacy. Therefore, different from the past literature, we capture such interactive effect and propose INCEPTION, a novel MCS system framework that integrates an incentive, a data aggregation, and a data perturbation mechanism. Specifically, its incentive mechanism selects workers who are more likely to provide reliable data and compensates their costs for both sensing and privacy leakage. Its data aggregation mechanism also incorporates workers’ reliability to generate highly accurate aggregated results, and its data perturbation mechanism ensures satisfactory protection for workers’ privacy and desirable accuracy for the final perturbed results. We validate the desirable properties of INCEPTION through theoretical analysis as well as extensive simulations.

31 August 2018 in IEEE Transactions on Mobile Computing
Verified
Journal Article
Closed access
HJHaiming Jin
Haiming Jin
LSLu Su
Lu Su
DCDanyang Chen
Danyang Chen
HGHongpeng Guo
Hongpeng Guo
Klara NahrstedtKlara Nahrstedt
Klara Nahrstedt
JXJinhui Xu
Jinhui Xu
Recent years have witnessed the emergence of mobile crowd sensing (MCS) systems, which leverage the public crowd equipped with various mobile devices for large scale sensing tasks. In this paper, we study a critical problem in MCS systems, namely, incentivizing worker participation. Different from existing work, we propose an incentive framework for MCS systems, named Thanos, that incorporates a crucial metric, called workers' quality of information (QoI). Due to various factors (e.g., sensor quality, environment noise), the quality of the sensory data contributed by individual workers varies significantly. Obtaining high quality data with little expense is always the ideal of MCS platforms. Technically, our design of Thanos is based on reverse combinatorial auctions. We investigate both the single- and multi-minded combinatorial auction models. For the former, we design a truthful, individual rational and computationally efficient mechanism that ensures a close-to-optimal social welfare. For the latter, we design an iterative descending mechanism that satisfies individual rationality and computational efficiency, and approximately maximizes the social welfare with a guaranteed approximation ratio. Through extensive simulations, we validate our theoretical analysis on the various desirable properties guaranteed by Thanos.

1 November 2018 in Computer
Verified
Journal Article
Closed access
TATarek Abdelzaher
Tarek Abdelzaher
NANora Ayanian
Nora Ayanian
TBTamer Başar
Tamer Başar
SDSuhas Diggavi
Suhas Diggavi
JDJana Diesner
Jana Diesner
VVVenu Veeravalli
Venu Veeravalli
The Internet of Battlefield Things (IoBT) might be one of the most expensive cyber-physical systems of the next decade, yet much research remains to develop its fundamental enablers. A challenge that distinguishes the IoBT from its civilian counterparts is resilience to a much larger spectrum of threats.

15 July 2021
Verified
Conference Paper
Open access
HGHongpeng Guo
Hongpeng Guo
SYShuochao Yao
Shuochao Yao
ZYZhe Yang
Zhe Yang
QZQian Zhou
Qian Zhou
Klara NahrstedtKlara Nahrstedt
Klara Nahrstedt
Video cameras are pervasively deployed in city scale for public good or community safety (i.e. traffic monitoring or suspected person tracking). However, analyzing large scale video feeds in real time is data intensive and poses severe challenges to today's network and computation systems. We present CrossRoI, a resource-efficient system that enables real time video analytics at scale via harnessing the videos content associations and redundancy across a fleet of cameras. CrossRoI exploits the intrinsic physical correlations of cross-camera viewing fields to drastically reduce the communication and computation costs. CrossRoI removes the repentant appearances of same objects in multiple cameras without harming comprehensive coverage of the scene. CrossRoI operates in two phases - an offline phase to establish cross-camera correlations, and an efficient online phase for real time video inference. Experiments on real-world video feeds show that CrossRoI achieves 42% ~ 65% reduction for network overhead and 25% ~ 34% reduction for response delay in real time video analytics applications with more than 99% query accuracy, when compared to baseline methods. If integrated with SotA frame filtering systems, the performance gains of CrossRoI reaches 50% ~ 80% (network overhead) and 33% ~ 61% (end-to-end delay).

5 January 2006
Verified
Conference Paper
Closed access
ZYZhenyu Yang
Zhenyu Yang
Klara NahrstedtKlara Nahrstedt
Klara Nahrstedt
YCYi Cui
Yi Cui
BYBin Yu
Bin Yu
LJLiang Jin
Liang Jin
RBR. Bajscy
R. Bajscy
Tele-immersive 3D multi-camera room environments are starting to emerge and with them new challenging research questions. One important question is how to organize the large amount of visual data, being captured, processed, transmitted and displayed, and their corresponding resources, over current COTS computing and networking infrastructures so that "everybody" would be able to install and use tele-immersive environments for conferencing and other activities. In this paper, we propose a novel cross-layer control and streaming framework over general purpose delivery infrastructure, called TEEVE (tele-immersive environments for everybody). TEEVE aims for effective and adaptive coordination, synchronization, and soft QoS-enabled delivery of tele-immersive visual streams to remote room(s). The TEEVE experiments between two tele-immersive rooms residing in different institutions more than 2000 miles apart show that we can sustain communication of up to 12 3D video streams with 4/spl sim/5 3D frames per second for each stream, yielding 4/spl sim/5 tele-immersive video rate.

8 November 2019 in IEEE/ACM Transactions on Networking
Verified
Journal Article
Closed access
HJHaiming Jin
Haiming Jin
BHBaoxiang He
Baoxiang He
LSLu Su
Lu Su
Klara NahrstedtKlara Nahrstedt
Klara Nahrstedt
XWXinbing Wang
Xinbing Wang
The recent proliferation of human-carried mobile devices has given rise to mobile crowd sensing (MCS) systems that outsource sensory data collection to the public crowd. In order to identify truthful values from (crowd) workers' noisy or even conflicting sensory data, truth discovery algorithms, which jointly estimate workers' data quality and the underlying truths through quality-aware data aggregation, have drawn significant attention. However, the power of these algorithms could not be fully unleashed in MCS systems, unless workers' strategic reduction of their sensing effort is properly tackled. To address this issue, in this paper, we propose a payment mechanism, named Theseus, that deals with workers' such strategic behavior, and incentivizes high-effort sensing from workers. We ensure that, at the Bayesian Nash Equilibrium of the non-cooperative game induced by Theseus, all participating workers will spend their maximum possible effort on sensing, which improves their data quality. As a result, the aggregated results calculated subsequently by truth discovery algorithms based on workers' data will be highly accurate. Additionally, Theseus bears other desirable properties, including individual rationality and budget feasibility. We validate the desirable properties of Theseus through theoretical analysis, as well as extensive simulations.