Chit-Kwan Lin

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We consider the problem of localizing wireless nodes in an outdoor, open-space environment, using ad-hoc radio ranging measurements, e.g., 802.11. We cast these ranging measurements as a set of distance constraints, thus forming an over-determined system of equations suitable for non-linear least squares optimization. However, ranging measurements are often(More)
We are interested in estimating the angle of arrival of an RF signal by using commercial-off-the-shelf (COTS) software-defined radios (SDRs). The proposed COTS-based approach has the advantages of flexibility, low cost and ease of deployment, but—unlike traditional phased antenna arrays in which elements are already phase-aligned—we face the challenge of(More)
We consider the problem of multi-hop content distribution over a wireless ad-hoc network. Such mechanisms are relevant to a broad spectrum of applications, but are particularly important to data broadcast in wireless distributed computing where speedy I/O is critical to overall performance. In this paper, we present Rainbow, a content distribution protocol(More)
We consider the problem of mitigating a highly varying wireless channel between a transmitting ground node and receivers on a small, low-altitude unmanned aerial vehicle (UAV) in a 802.11 wireless mesh network. One approach is to use multiple transmitter and receiver nodes that exploit the channel’s spatial/temporal diversity and that cooperate to improve(More)
The recent growth in wavelength division multiplexing has increased the demand for easy-to-integrate wavelengthsensitive photodetectors and wavelength monitors. Various devices have been proposed for wavelength-sensitive photodetectors, including Fabry–Perot resonator devices, tunable filters integrated with a photodetector, and Mach–Zehnder designs for(More)
Continuous fine-grain status monitoring of a cloud data center enables rapid response to anomalies, but handling the resulting torrent of data poses a significant challenge. As a solution, we propose CloudSense, a new switch design that performs in-network compression of status streams via compressive sensing. Using MapReduce straggler detection as an(More)
Mobile device hardware can limit the sophistication of mobile applications. One strategy for side-stepping these constraints is to opportunistically offload computations to the cloud, where more capable hardware can do the heavy lifting. We propose a platform that accomplishes this via compressive offloading, a novel application of compressive sensing in a(More)
Wireless data transfer under high mobility, as found in unmanned aerial vehicle (UAV) applications, is a challenge due to varying channel quality and extended link outages. We present FlowCode, an easily deployable link-layer solution utilizing multiple transmitters and receivers for the purpose of supporting existing transport protocols such as TCP in(More)
MapReduce job execution typically occurs in sequential phases of parallel steps. These phases can experience unpredictable delays when available computing and network capacities fluctuate or when there are large disparities in inter-node communication delays, as can occur on shared compute clouds. We propose a pipeline-based scheduling strategy, called(More)
In this paper, we use a finite-state model to predict the performance of the Transmission Control Protocol (TCP) over a varying wireless channel between an unmanned aerial vehicle (UAV) and ground nodes. As a UAV traverses its flight path, the wireless channel may experience periods of significant packet loss, successful packet delivery, and intermittent(More)