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Browsing by Author "Lu, Guor-Huar"

Now showing 1 - 2 of 2
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    Enhancing location service scalability with HIGH-GRADE
    (2004-01-12) Yu, Yinzhe; Lu, Guor-Huar; Zhang, Zhi-Li
    Location-based routing significantly reduces routing overheads in ad hoc networks by utilizing position information of mobile nodes in making forwarding decisions. Location service is therefore critical to location-based routing, the scalability of which hinges largely on the location query and update overheads of such service. Although several location service schemes have been proposed, most of them focus only on one or two aspects of the scalability in their performance evaluation, and a comprehensive comparative study is missing. In this paper, we first explore the design space of location service for location-based ad hoc routing and discuss the tradeoffs involved in various design choices. We then propose HIGH-GRADE, a new location service scheme that employs a multilevel hierarchical location server structure and a multi-grained location information organization. We develop a uniform theoretical framework to analyze HIGH-GRADE and four other existing schemes in terms of three metrics: location maintenance cost, location query cost, and storage requirement cost. With both theoretical analysis and simulation experiments, we show that HIGH-GRADE demonstrates superior scalability, especially when a localized data traffic pattern is assumed, in which case all the three scalability metrics are bound byO(v log N).
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    Vault: A Secure Binding Service
    (2006-11-10) Lu, Guor-Huar; Choi, Changho; Zhang, Zhi-Li
    Binding services are crucial building blocks in networks and networked applications. A binding service (e.g., the Domain Name System (DNS)) maps certain information, namely, binding keys (e.g., host names), to other information, i.e., binding values (e.g., IP addresses), and answers queries for such key-value bindings. In a sense, a binding service is a specialized look-up service where each binding has an owner (the user who registers the binding), and only the owner can update or delete the binding. Clearly, building secure binding services that ensure the integrity and authenticity of bindings are vital to the correct operations of many networks and networked applications. In this paper we present a novel approach for building generic secure binding services that allow arbitrary key-value bindings as (trusted) infrastructure services to support a variety of networks and networked applications. We combine the Identity-Based Encryption (IBE) crypto-mechanisms with distributed hash table (DHT) techniques to develop an innovative architecture for building scalable, robust and secure binding services. Using this architecture, we implement a prototype system called Vault and evaluate its performance both in a local testbed and on the PlanetLab.