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Mobile Computing, IEEE Transactions on

Issue 1 • Date Jan. 2008

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Displaying Results 1 - 16 of 16
  • [Front cover]

    Page(s): c1
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  • [Inside front cover]

    Page(s): c2
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  • Protecting Location Privacy with Personalized k-Anonymity: Architecture and Algorithms

    Page(s): 1 - 18
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2472 KB) |  | HTML iconHTML  

    Continued advances in mobile networks and positioning technologies have created a strong market push for location-based applications. Examples include location-aware emergency response, location-based advertisement, and location-based entertainment. An important challenge in the wide deployment of location-based services (LBSs) is the privacy-aware management of location information, providing safeguards for location privacy of mobile clients against vulnerabilities for abuse. This paper describes a scalable architecture for protecting the location privacy from various privacy threats resulting from uncontrolled usage of LBSs. This architecture includes the development of a personalized location anonymization model and a suite of location perturbation algorithms. A unique characteristic of our location privacy architecture is the use of a flexible privacy personalization framework to support location k-anonymity for a wide range of mobile clients with context-sensitive privacy requirements. This framework enables each mobile client to specify the minimum level of anonymity that it desires and the maximum temporal and spatial tolerances that it is willing to accept when requesting k-anonymity-preserving LBSs. We devise an efficient message perturbation engine to implement the proposed location privacy framework. The prototype that we develop is designed to be run by the anonymity server on a trusted platform and performs location anonymization on LBS request messages of mobile clients such as identity removal and spatio-temporal cloaking of the location information. We study the effectiveness of our location cloaking algorithms under various conditions by using realistic location data that is synthetically generated from real road maps and traffic volume data. Our experiments show that the personalized location k-anonymity model, together with our location perturbation engine, can achieve high resilience to location privacy threats without introducing any significant- - performance penalty. View full abstract»

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  • The COMMIT Protocol for Truthful and Cost-Efficient Routing in Ad Hoc Networks with Selfish Nodes

    Page(s): 19 - 33
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (532 KB) |  | HTML iconHTML  

    We consider the problem of establishing a route and sending packets between a source/destination pair in ad hoc networks composed of rational selfish nodes whose purpose is to maximize their own utility. In order to motivate nodes to follow the protocol specification, we use side payments that are made to the forwarding nodes. Our goal is to design a fully distributed algorithm such that (1) a node is always better off participating in the protocol execution (individual rationality), (2) a node is always better off behaving according to the protocol specification (truthfulness), (3) messages are routed along the most energy-efficient (least cost) path, and (4) the message complexity is reasonably low. We introduce the COMMIT protocol for individually rational, truthful, and energy-efficient routing in ad hoc networks. To the best of our knowledge, this is the first ad hoc routing protocol with these features. COMMIT is based on the VCG payment scheme in conjunction with a novel game-theoretic technique to achieve truthfulness for the sender node. By means of simulation, we show that the inevitable economic inefficiency is small. As an aside, our work demonstrates the advantage of using a cross-layer approach to solving problems: Leveraging the existence of an underlying topology control protocol, we are able to simplify the design and analysis of our routing protocol and reduce its message complexity. On the other hand, our investigation of the routing problem in the presence of selfish nodes disclosed a new metric under which topology control protocols can be evaluated: the cost of cooperation. View full abstract»

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  • Improving Throughput and Fairness by Reducing Exposed and Hidden Nodes in 802.11 Networks

    Page(s): 34 - 49
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    Two well-known problems that can cause performance degradations in IEEE 802.11 wireless networks are the exposed-node (EN) and hidden-node (HN) problems. Although there have been isolated and incidental studies of EN and HN, a comprehensive treatment has not been attempted. The contributions of this paper are threefold: First, we provide rigorous mathematical definitions for EN and HN in wireless networks (including wireless local area networks (WLANs) with multiple access points (APs) and ad hoc networks). Second, we relate EN to the nonscalability of network throughput and HN to unfair throughput distributions. Third, we provide schemes to eliminate EN and HN, respectively. We show that the standard 802.11 technology is not scalable because, due to EN, more APs do not yield higher total throughput. By removing EN, our schemes make it possible to achieve scalable throughput commensurate with the seminal theoretical results in [1] and [2]. In addition, by removing HN, our schemes solve the performance problems triggered by HN, including throughput unfairness/starvation and rerouting instability. View full abstract»

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  • Comparison of Multichannel MAC Protocols

    Page(s): 50 - 65
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    This paper compares, through analysis and simulation, a number of multichannel MAC protocols. We first classify these protocols into four categories based on their principles of operation: dedicated control channel, common hopping, split phase, and parallel rendezvous protocols. We then examine the effects of the number of channels and devices, channel switching times, and traffic patterns on the throughput and delay of the protocols. Here are some of the conclusions of our study: (1) parallel rendezvous protocols generally perform better than single rendezvous protocols, (2) the dedicated control channel protocol can be a good approach with its simplicity when the number of channels is high and the packets are long, and (3) the split phase protocol is very sensitive to the durations of the control and data phases. Our study focuses on a single collision domain. View full abstract»

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  • On Localized Application-Driven Topology Control for Energy-Efficient Wireless Peer-to-Peer File Sharing

    Page(s): 66 - 80
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    Wireless peer-to-peer (P2P) file sharing is widely envisioned as one of the major applications of ad hoc networks in the near future. This trend is largely motivated by the recent advances in high-speed wireless communication technologies and high traffic demand for P2P file sharing applications. To achieve the ambitious goal of realizing a practical wireless P2P network, we need a scalable topology control protocol to solve the neighbor discovery problem and network organization problem. Indeed, we believe that the topology control mechanism should be application driven in that we should try to achieve an efficient connectivity among mobile devices in order to better serve the file sharing application. We propose a new protocol, which consists of two components, namely, adjacency set construction (ASC) and community-based asynchronous wakeup (CAW). Our proposed protocol is shown to be able to enhance the fairness and provide an incentive mechanism in wireless P2P file sharing applications. It is also capable of increasing the energy efficiency. View full abstract»

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  • Sequence-Based Localization in Wireless Sensor Networks

    Page(s): 81 - 94
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    We introduce a novel sequence-based localization technique for wireless sensor networks. We show that the localization space can be divided into distinct regions that can each be uniquely identified by sequences that represent the ranking of distances from the reference nodes to that region. For n reference nodes in the localization space, combinatorially, O(n") sequences are possible, but we show that, due to geometric constraints, the actual number of feasible location sequences is much lower: only O(n 4). Using these location sequences, we develop a localization technique that is robust to random errors due to the multipath and shadowing effects of wireless channels. Through extensive systematic simulations and a representative set of real mote experiments, we show that our lightweight localization technique provides comparable or better accuracy than other state-of-the-art radio signal strength-based localization techniques over a range of wireless channel and node deployment conditions. View full abstract»

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  • A New Call Admission Control Mechanism for Multimedia Traffic over Next-Generation Wireless Cellular Networks

    Page(s): 95 - 112
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    The subject of Call Admission Control (CAC) for wireless networks has been studied extensively in the literature. Another subject on which many researchers have focused their attention is that of video traffic modeling. However, user mobility, combined with the rapidly growing number of "greedy" multimedia applications, in terms of bandwidth and Quality of Service (QoS) requirements, form a challenging and yet unresolved problem for third and fourth-generation wireless networks. In recent work, we have built a Discrete Autoregressive (DAR (1)) model to capture the behavior of multiplexed H.263 videoconference movies from variable bit rate (VBR) coders. Based on this model, we propose in this work a new efficient CAC scheme for wireless cellular networks, which differs from the existing proposals in the literature in that it uses precomputed traffic scenarios combined with online simulation for its decision making. Our scheme is shown, via an extensive simulation study comparison and a conceptual comparison with well-known existing approaches, to clearly excel in terms of QoS provisioning to users receiving videoconference videoconference and Web traffic. To the best of our knowledge, this is the first work in the relevant literature where such an approach has been proposed. View full abstract»

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  • Study of Beaconing in Multihop Wireless PAN with Distributed Control

    Page(s): 113 - 126
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    Distributed media access control (MAC) architecture has many merits to make it a favorable candidate for high-data-rate wireless personal area networks (WPANs) with physical layer (PHY) based on ultrawideband (UWB) technology. This paper focuses on the WiMedia MAC, which is the first distributed MAC for WPANs, approved as a standard. In such a MAC, all devices transmit their beacons to provide timing reference and to broadcast control and reservation information, that is, to maintain device synchronization. We investigate problems related to beacon collisions, which occur when multiple devices join a piconet almost at the same time. To join a piconet or to resolve a collision, a device chooses a slot for its beacon randomly within some window. We show that an improper slot choice scheme leads to repeated collisions, increasing the time overhead to achieve device synchronization. It also leads devices into trouble in joining and collision resolution, even into deadlocks, when devices have no chance to escape repeated collisions. We develop an analytical model to evaluate the performance of various slot choice schemes for multihop WPANs. The model is employed to compare the efficiency of these choice schemes and to optimize their parameters to achieve the best performance. View full abstract»

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  • Boundary Mapping and Boundary-State Routing (BSR) in Ad Hoc Networks

    Page(s): 127 - 139
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2280 KB) |  | HTML iconHTML  

    This paper presents a geographic routing protocol, boundary state routing (BSR), which consists of two components. The first is an improved forwarding strategy, greedy-bounded compass, which can forward packets around concave boundaries, where the packet moves away from the destination without looping. The second component is a boundary mapping protocol (BMP), which is used to maintain link state information for boundaries containing concave vertices. The proposed forwarding strategy greedy-bounded compass is shown to produce a higher rate of path completion than Greedy forwarding and significantly improves the performance of greedy perimeter state routing (GPSR) in sparse networks when used in place of greedy forwarding. The proposed geographic routing protocol BSR is shown to produce significant improvements in performance in comparison to GPSR in sparse networks due to informed decisions regarding the direction of boundary traversal at local minima. View full abstract»

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  • 2007 Reviewers List

    Page(s): 140 - 143
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    Freely Available from IEEE
  • Join the IEEE Computer Society [advertisement]

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    Freely Available from IEEE
  • 2007 Annual Index

    Page(s): not in print
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    Freely Available from IEEE
  • TMC Information for authors

    Page(s): c3
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    Freely Available from IEEE
  • [Back cover]

    Page(s): c4
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Aims & Scope

Mobile Computing, as proposed in this Transactions, focuses on the key technical issues related to (a) architectures, (b) support services, (c) algorithm/protocol design and analysis, (d) mobile environments, (e) mobile communication systems, (f) applications, and (g) emerging technologies.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Prasant Mohapatra
Interim Vice-Provost and CIO
Professor, Dept. Computer Science
University of California, Davis, USA
pmohapatra@ucdavis.edu