By Topic

Mobile Computing, IEEE Transactions on

Issue 6 • Date June 2009

Filter Results

Displaying Results 1 - 15 of 15
  • [Front cover]

    Publication Year: 2009 , Page(s): c1
    Save to Project icon | Request Permissions | PDF file iconPDF (306 KB)  
    Freely Available from IEEE
  • [Inside front cover]

    Publication Year: 2009 , Page(s): c2
    Save to Project icon | Request Permissions | PDF file iconPDF (122 KB)  
    Freely Available from IEEE
  • Fair Class-Based Downlink Scheduling with Revenue Considerations in Next Generation Broadband Wireless Access Systems

    Publication Year: 2009 , Page(s): 721 - 734
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3356 KB) |  | HTML iconHTML  

    The success of emerging Broadband Wireless Access Systems (BWASs) will depend, among other factors, on their ability to manage their shared wireless resources in the most efficient way. This is a complex task due to the heterogeneous nature, and hence, diverse Quality of Service (QoS) requirements of different applications that these systems support. Therefore, QoS provisioning is crucial for the success of such wireless access systems. In this paper, we propose a novel downlink packet scheduling scheme for QoS provisioning in BWASs. The proposed scheme employs practical economic models through the use of novel utility and opportunity cost functions to simultaneously satisfy the diverse QoS requirements of mobile users and maximize the revenues of network operators. Unlike existing schemes, the proposed scheme is general and can support multiple QoS classes with users having different QoS and traffic demands. To demonstrate its generality, we show how the utility function can be used to support three different types of traffic, namely best-effort traffic, traffic with minimum data rate requirements, and traffic with maximum packet delay requirements. Extensive performance analysis is carried out to show the effectiveness and strengths of the proposed packet scheduling scheme. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Cell Breathing Techniques for Load Balancing in Wireless LANs

    Publication Year: 2009 , Page(s): 735 - 749
    Cited by:  Papers (32)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2721 KB) |  | HTML iconHTML  

    Maximizing network throughput while providing fairness is one of the key challenges in wireless LANs (WLANs). This goal is typically achieved when the load of access points (APs) is balanced. Recent studies on operational WLANs, however, have shown that AP load is often substantially uneven. To alleviate such imbalance of load, several load balancing schemes have been proposed. These schemes commonly require proprietary software or hardware at the user side for controlling the user-AP association. In this paper we present a new load balancing technique by controlling the size of WLAN cells (i.e., AP's coverage range), which is conceptually similar to cell breathing in cellular networks. The proposed scheme does not require any modification to the users neither the IEEE 802.11 standard. It only requires the ability of dynamically changing the transmission power of the AP beacon messages. We develop a set of polynomial time algorithms that find the optimal beacon power settings which minimize the load of the most congested AP. We also consider the problem of network-wide min-max load balancing. Simulation results show that the performance of the proposed method is comparable with or superior to the best existing association-based methods. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Mobility-Prediction-Based Relay Deployment Framework for Conserving Power in MANETs

    Publication Year: 2009 , Page(s): 750 - 765
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3588 KB) |  | HTML iconHTML  

    There has been a growing interest in designing mobile systems consisting of special relay nodes whose mobility can be controlled by the underlying network. In this paper, we consider the design of a heterogeneous mobile ad hoc network (MANET) consisting of two kinds of mobile nodes-traditional nodes with limited energy and a few controllable mobile relay nodes with relatively abundant energy resources. We propose a novel relay deployment framework that utilizes mobility prediction and works in tandem with the underlying MANET routing protocol to optimally define the movement of the relay nodes. We present two instances of the relay deployment problem, together with the solutions, to achieve different goals. Instance 1, termed Min-Total, aims to minimize the total energy consumed across all the traditional nodes during data transmission, while instance 2, termed Min-Max, aims to minimize the maximum energy consumed by a traditional node during data transmission. Our solutions also enable the prioritization of individual nodes in the network based on residual energy profiles and contextual significance. We perform an extensive simulation study to understand the trade-offs involved in deploying an increasing fraction of such relay nodes in the network. We also investigate the performance of the proposed framework under different mobility prediction schemes. Results indicate that even when the relay nodes constitute a small fraction of the total nodes in the network, the proposed framework results in significant energy savings. Further, we observed that while both the schemes have their potential advantages, the differences between the two optimization schemes are clearly highlighted in a sparse network. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Opportunistic Scheduling with Reliability Guarantees in Cognitive Radio Networks

    Publication Year: 2009 , Page(s): 766 - 777
    Cited by:  Papers (62)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (650 KB) |  | HTML iconHTML  

    We develop opportunistic scheduling policies for cognitive radio networks that maximize the throughput utility of the secondary (unlicensed) users subject to maximum collision constraints with the primary (licensed) users. We consider a cognitive network with static primary users and potentially mobile secondary users. We use the technique of Lyapunov optimization to design an online flow control, scheduling, and resource allocation algorithm that meets the desired objectives and provides explicit performance guarantees. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Energy Maps for Mobile Wireless Networks: Coherence Time versus Spreading Period

    Publication Year: 2009 , Page(s): 778 - 791
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2934 KB) |  | HTML iconHTML  

    We show that even though mobile networks are highly unpredictable when viewed at the individual node scale, the end-to-end quality-of-service (QoS) metrics can be stationary when the mobile network is viewed in the aggregate. We define the coherence time as the maximum duration for which the end-to-end QoS metric remains roughly constant, and the spreading period as the minimum duration required to spread QoS information to all the nodes. We show that if the coherence time is greater than the spreading period, the end-to-end QoS metric can be tracked. We focus on the energy consumption as the end-to-end QoS metric, and describe a novel method by which an energy map can be constructed and refined in the joint memory of the mobile nodes. Finally, we show how energy maps can be utilized by an application that aims to minimize a node's total energy consumption over its near-future trajectory. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Shake Well Before Use: Intuitive and Secure Pairing of Mobile Devices

    Publication Year: 2009 , Page(s): 792 - 806
    Cited by:  Papers (12)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2053 KB) |  | HTML iconHTML  

    A challenge in facilitating spontaneous mobile interactions is to provide pairing methods that are both intuitive and secure. Simultaneous shaking is proposed as a novel and easy-to-use mechanism for pairing of small mobile devices. The underlying principle is to use common movement as a secret that the involved devices share for mutual authentication. We present two concrete methods, ShaVe and ShaCK, in which sensing and analysis of shaking movement is combined with cryptographic protocols for secure authentication. ShaVe is based on initial key exchange followed by exchange and comparison of sensor data for verification of key authenticity. ShaCK, in contrast, is based on matching features extracted from the sensor data to construct a cryptographic key. The classification algorithms used in our approach are shown to robustly separate simultaneous shaking of two devices from other concurrent movement of a pair of devices, with a false negative rate of under 12 percent. A user study confirms that the method is intuitive and easy to use, as users can shake devices in an arbitrary pattern. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Maximum-Rate Node Selection for Power-Limited Multiantenna Relay Backbones

    Publication Year: 2009 , Page(s): 807 - 820
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1383 KB) |  | HTML iconHTML  

    Wireless mesh networks (WMNs) are envisioned for extending the coverage of WLANs by interconnecting the underlying access points (APs) via high-capacity wireless backbones. Since the ultimate goal of a WMN is to provide Internet connectivity to residential clients, WMN traffic is mainly routed over the backbone either toward the Internet gateways (IGWs) or from the IGWs to the APs. In principle, the transport capacity of a WMN can further be upgraded by equipping the underlying backbone routers with multiantenna (MA) radio modules. Motivated by the above consideration, in this paper, we focus on the optimized node selection (e.g., path-routing) over MA mesh backbones when the target is to maximize the end-to-end routed information rate subject to a constraint on the total power available for the relays. Under the assumption of Rayleigh-distributed block fading, we assume that point-to-point capacity-achieving space-time codes (STCs) are used for the single-hop link. At first, we tackle the routing problem when neither interference mitigation (IM) nor transmit beamforming (TB) is performed at the relay nodes, and then, we extend the analysis to the cases when IM and/or TB are also carried out. The effects of channel-state-information (CSI) possibly available at the relay nodes are also investigated. So doing, we are able to gain insight about the combined effect of spatial multiplexing and IM capabilities of the overall MA architecture on both end-to-end capacity and access medium performance of the considered WMN. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Large Connectivity for Dynamic Random Geometric Graphs

    Publication Year: 2009 , Page(s): 821 - 835
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (969 KB) |  | HTML iconHTML  

    We provide the first rigorous analytical results for the connectivity of dynamic random geometric graphs - a model for mobile wireless networks in which vertices move in random directions in the unit torus. The model presented here follows the one described. We provide precise asymptotic results for the expected length of the connectivity and disconnectivity periods of the network. We believe that the formal tools developed in this work could be extended to be used in more concrete settings and in more realistic models, in the same manner as the development of the connectivity threshold for static random geometric graphs has affected a lot of research done on ad hoc networks. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Connectivity-Guaranteed and Obstacle-Adaptive Deployment Schemes for Mobile Sensor Networks

    Publication Year: 2009 , Page(s): 836 - 848
    Cited by:  Papers (20)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2396 KB) |  | HTML iconHTML  

    Mobile sensors can relocate and self-deploy into a network. While focusing on the problems of coverage, existing deployment schemes largely oversimplify the conditions for network connectivity: they either assume that the communication range is large enough for sensors in geometric neighborhoods to obtain location information through local communication, or they assume a dense network that remains connected. In addition, an obstacle-free field or full knowledge of the field layout is often assumed. We present new schemes that are not governed by these assumptions, and thus adapt to a wider range of application scenarios. The schemes are designed to maximize sensing coverage and also guarantee connectivity for a network with arbitrary sensor communication/sensing ranges or node densities, at the cost of a small moving distance. The schemes do not need any knowledge of the field layout, which can be irregular and have obstacles/holes of arbitrary shape. Our first scheme is an enhanced form of the traditional virtual-force-based method, which we term the connectivity-preserved virtual force (CPVF) scheme. We show that the localized communication, which is the very reason for its simplicity, results in poor coverage in certain cases. We then describe a floor-based scheme which overcomes the difficulties of CPVF and, as a result, significantly outperforms it and other state-of-the-art approaches. Throughout the paper our conclusions are corroborated by the results from extensive simulations. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • TMSP: Terminal Mobility Support Protocol

    Publication Year: 2009 , Page(s): 849 - 863
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2486 KB) |  | HTML iconHTML  

    Mobile IP enables IP mobility support for mobile node (MN), but it suffers from triangular routing, packet redirecting, increase in IP header size, and the need for new infrastructure support. This paper details an alternative to enable terminal mobility support for MN. This scheme does not suffer from triangular routing effect and does not require dedicated infrastructure support such as home agent. It also does not increase the size of the IP header and does not require redirection of packets. These benefits are enabled with a tradeoff, which requires modifications on MN and its correspondent node. It uses an innovative IP-to-IP address mapping method to provide IP address transparency for applications and taps on the pervasiveness of SIP as a location service. From our analysis, we show that TMSP is much more efficient than mobile IP in terms of the number of hops as well as overhead. Our prototype implementation also shows that TMSP provides seamless communication for both TCP and UDP connections and the computational overhead for TMSP has minimal impact on packet transmission. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • IEEE Computer Society Career Center

    Publication Year: 2009 , Page(s): 864
    Save to Project icon | Request Permissions | PDF file iconPDF (308 KB)  
    Freely Available from IEEE
  • TMC Information for authors

    Publication Year: 2009 , Page(s): c3
    Save to Project icon | Request Permissions | PDF file iconPDF (122 KB)  
    Freely Available from IEEE
  • [Back cover]

    Publication Year: 2009 , Page(s): c4
    Save to Project icon | Request Permissions | PDF file iconPDF (306 KB)  
    Freely Available from IEEE

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