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Full-Text Articles in Physical Sciences and Mathematics
Modeling Users' Mobility Among Wifi Access Points, Minkyong Kim, David Kotz
Modeling Users' Mobility Among Wifi Access Points, Minkyong Kim, David Kotz
Dartmouth Scholarship
Modeling movements of users is important for simulating wireless networks, but current models often do not reflect real movements. Using real mobility traces, we can build a mobility model that reflects reality. In building a mobility model, it is important to note that while the number of handheld wireless devices is constantly increasing, laptops are still the majority in most cases. As a laptop is often disconnected from the network while a user is moving, it is not feasible to extract the exact path of the user from network messages. Thus, instead of modeling individual user's movements, we model movements …
Analysis Of A Wi-Fi Hotspot Network, David P. Blinn, Tristan Henderson, David Kotz
Analysis Of A Wi-Fi Hotspot Network, David P. Blinn, Tristan Henderson, David Kotz
Dartmouth Scholarship
Wireless hotspot networks have become increasingly popular in recent years as a means of providing Internet access in public areas such as restaurants and airports. In this paper we present the first study of such a hotspot network. We examine five weeks of SNMP traces from the Verizon Wi-Fi HotSpot network in Manhattan. We find that far more cards associated to the network than logged into it. Most clients used the network infrequently and visited few APs. AP utilization was uneven and the network displayed some unusual patterns in traffic load. Some characteristics were similar to those previously observed in …
Classifying The Mobility Of Users And The Popularity Of Access Points, Minkyong Kim, David Kotz
Classifying The Mobility Of Users And The Popularity Of Access Points, Minkyong Kim, David Kotz
Dartmouth Scholarship
There is increasing interest in location-aware systems and applications. It is important for any designer of such systems and applications to understand the nature of user and device mobility. Furthermore, an understanding of the effect of user mobility on access points (APs) is also important for designing, deploying, and managing wireless networks. Although various studies of wireless networks have provided insights into different network environments and user groups, it is often hard to apply these findings to other situations, or to derive useful abstract models. \par In this paper, we present a general methodology for extracting mobility information from wireless …
Measuring Wireless Network Usage With The Experience Sampling Method, Tristan Henderson, Denise Anthony, David Kotz
Measuring Wireless Network Usage With The Experience Sampling Method, Tristan Henderson, Denise Anthony, David Kotz
Dartmouth Scholarship
Measuring wireless local area networks has proven useful for characterizing, modeling and provisioning these networks. These measurements are typically taken passively from a vantage point on the network itself. Client devices, or users, are never actively queried. These measurements can indicate \em what is happening on the network, but it can be difficult to infer \em why a particular behavior is occurring. In this paper we use the Experience Sampling Method (ESM) to study wireless network users. We monitored 29 users remotely for one week, and signaled them to fill out a questionnaire whenever interesting wireless behavior was observed. We …
Secure Context-Sensitive Authorization, Kazuhiro Minami, David Kotz
Secure Context-Sensitive Authorization, Kazuhiro Minami, David Kotz
Dartmouth Scholarship
There is a recent trend toward rule-based authorization systems to achieve flexible security policies. Also, new sensing technologies in pervasive computing make it possible to define context-sensitive rules, such as “allow database access only to staff who are currently located in the main office.” However, these rules, or the facts that are needed to verify authority, often involve sensitive context information. This paper presents a secure context-sensitive authorization system that protects confidential information in facts or rules. Furthermore, our system allows multiple hosts in a distributed environment to perform the evaluation of an authorization query in a collaborative way; we …
Policy-Driven Data Dissemination For Context-Aware Applications, Guanling Chen, David Kotz
Policy-Driven Data Dissemination For Context-Aware Applications, Guanling Chen, David Kotz
Dartmouth Scholarship
Context-aware pervasive-computing applications require continuous monitoring of their physical and computational environment to make appropriate adaptation decisions in time. The data streams produced by sensors, however, may overflow the queues on the dissemination path. Traditional flow-control and congestion-control policies either drop data or force the sender to pause. When the data sender is sensing the physical environment, however, a pause is equivalent to dropping data. Instead of arbitrarily dropping data that may contain important events, we present a policy-driven data dissemination service named PACK, based on an overlay-based infrastructure for efficient multicast delivery. PACK enforces application-specified policies that define how …