Lifeng Sang

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A substantial percentage of links in wireless networks, especially low-power ones, is asymmetric. For the low-quality direction of asymmetric links, we observe based on testbed experiments that the reliability of synchronous acknowledgments is considerably higher than that of asynchronous messages. Thus the norm of estimating link quality in both directions(More)
Link asymmetry is one of the unique challenges that wireless sensor networks pose in the design of network protocols. We observe, based on testbed experiments, that a substantial percentage of links are asymmetric, many are even unidirectional. We also find that the reliability of synchronous acknowledgments is considerably higher than that of asynchronous(More)
The wireless network community has become increasingly aware of the benefits of data-driven link estimation and routing as compared with beacon-based approaches, but the issue of <i>Biased Link Sampling</i> (BLS) estimation has not been well studied even though it affects routing convergence in the presence of network and environment dynamics. Focusing on(More)
Network security devices are becoming more sophisticated and so are the testing processes. Traditional network testbeds face challenges in terms of fidelity, scalability and complexity of security features. In this paper we propose a new methodology of testing security devices using network virtualization techniques, and present an integrated solution,(More)
—Link estimation is a basic element of routing in low-power wireless networks, and data-driven link estimation using unicast MAC feedback has been shown to outperform broadcast-beacon based link estimation. Nonetheless, little is known about the impact that different data-driven link estimation methods have on routing behaviors. To address this issue, we(More)
We answer the following questions for routing in wireless sensor networks: 1) should broadcast beacon or data serve as the basis of link estimation? 2) how to use MAC feedback in data-driven link estimation and rout-ing? 3) how to address the issue of biased link sampling in data-driven link estimation and routing. Keywords: wireless sensor networks,(More)
The wireless network community has become increasingly aware of the benefits of data-driven link estimation and routing as compared with beacon-based approaches, but the issue of biased link sampling (BLS) has not been well studied even though it affects routing convergence in the presence of network and environment dynamics. Focusing on traffic-induced(More)