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Mobile Computing, IEEE Transactions on

Issue 4 • Date Oct.-Dec. 2004

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Displaying Results 1 - 17 of 17
  • [Front cover]

    Publication Year: 2004 , Page(s): c1
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  • [Inside front cover]

    Publication Year: 2004 , Page(s): c2
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  • Guest Editorial

    Publication Year: 2004 , Page(s): 305 - 306
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  • Multiple access protocol for power-controlled wireless access nets

    Publication Year: 2004 , Page(s): 307 - 316
    Cited by:  Papers (32)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (632 KB) |  | HTML iconHTML  

    We consider ad hoc wireless networks that are configured as Mobile Backbone Networks. A hierarchical network architecture is synthesized, consisting of Access Nets (ANets) and Backbone Nets (BNets). Each ANet is managed by a (dynamically elected) Backbone Node (BN) that is equipped with higher capability (transmission and processing) modules. The BNs are chosen from currently active mobile backbone-capable nodes or are represented by (ground and/or airborne) unmanned vehicles (UVs) that are guided into selected positions. We develop and investigate a new joint power controlled medium access control (MAC) algorithm for wireless access nets (ANets). Under our new protocol, the net backbone node instructs the ANet nodes to make power control adjustments while simultaneously allocating to them slots for the requested transmissions of their packets. This algorithm, in contrast to other employed conventional graph-based scheduling algorithms, satisfies the requirement that a minimum signal-to-interference and noise ratio (SINR) is met at all intended receivers. We show our algorithm to lead to a significant increase in the net throughput level by attaining high spatial reuse. View full abstract»

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  • Methods for scalable self-assembly of ad hoc wireless sensor networks

    Publication Year: 2004 , Page(s): 317 - 331
    Cited by:  Papers (12)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1504 KB) |  | HTML iconHTML  

    In distributed wireless sensing applications such as unattended ground sensor systems, remote planetary exploration, and condition-based maintenance, where the deployment site is remote and/or the scale of the network is large, individual emplacement and configuration of the sensor nodes is difficult. Hence, network self-assembly and continuous network self-organization during the lifetime of the network in a reliable, efficient, and scalable manner are crucial for successful deployment and operation of such networks. This paper provides an overview of the concept of network self-assembly for ad hoc wireless sensor networks at the link layer, with descriptions of results from implementation of a novel network formation mechanism for wireless unattended ground sensor applications using a multicluster hierarchical topology and a novel dual-radio architecture. View full abstract»

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  • Guest Editorial

    Publication Year: 2004 , Page(s): 332 - 333
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  • Rate performance objectives of multihop wireless networks

    Publication Year: 2004 , Page(s): 334 - 349
    Cited by:  Papers (57)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (608 KB) |  | HTML iconHTML  

    We consider the question of what performance metric to maximize when designing ad hoc wireless network protocols such as routing or MAC. We focus on maximizing rates under battery-lifetime and power constraints. Commonly used metrics are total capacity (in the case of cellular networks) and transport capacity (in the case of ad hoc networks). However, it is known in traditional wired networking that maximizing total capacity conflicts with fairness, and this is why fairness-oriented rate allocations, such as max-min fairness, are often used. We review this issue for wireless ad hoc networks. Indeed, the mathematical model for wireless networks has a specificity that makes some of the findings different. It has been reported in the literature on ultra wide band that gross unfairness occurs when maximizing total capacity or transport capacity, and we confirm by a theoretical analysis that this is a fundamental shortcoming of these metrics in wireless ad hoc networks, as it is for wired networks. The story is different for max-min fairness. Although it is perfectly viable for a wired network, it is much less so in our setting. We show that, in the limit of long battery lifetimes, the max-min allocation of rates always leads to strictly equal rates, regardless of the MAC layer, network topology, channel variations, or choice of routes and power constraints. This is due to the "solidarity" property of the set of feasible rates. This results in all flows receiving the rate of the worst flow, and leads to severe inefficiency. We show numerically that the problem persists when battery-lifetime constraints are finite. This generalizes the observation reported in the literature that, in heterogeneous settings, 802.11 allocates the worst rate to all stations, and shows that this is inherent to any protocol that implements max-min fairness. Utility fairness is an alternative to max-min fairness, which approximates rate allocation performed by TCP in the Internet. We analyze by numerical simulations different utility functions and we show that the proportional fairness of rates or transport rates, a particular instance of utility-based metrics, is robust and achieves a good tradeoff between efficiency and fairness, unlike total rate or maximum fairness. We thus recommend - that metrics for the rate performance of mobile ad hoc networking protocols be based on proportional fairness. View full abstract»

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  • Medium access control in ad hoc networks with MIMO links: optimization considerations and algorithms

    Publication Year: 2004 , Page(s): 350 - 365
    Cited by:  Papers (78)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (989 KB) |  | HTML iconHTML  

    we present a medium access control (MAC) protocol for ad hoc networks with multiple input multiple output (MIMO) links. MIMO links provide extremely high spectral efficiencies in multipath channels by simultaneously transmitting multiple independent data streams in the same channel. MAC protocols have been proposed in related work for ad hoc networks with other classes of smart antennas such as switched beam antennas. However, as we substantiate in the paper, the unique characteristics of MIMO links coupled with several key optimization considerations, necessitate an entirely new MAC protocol. We identify several advantages of MIMO links, and discuss key optimization considerations that can help in realizing an effective MAC protocol for such an environment. We present a centralized algorithm called stream-controlled medium access (SCMA) that has the key optimization considerations incorporated in its design. Finally, we present a distributed SCMA protocol that approximates the centralized algorithm and compare its performance against that of baseline protocols that are CSMA/CA variants. View full abstract»

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  • HEED: a hybrid, energy-efficient, distributed clustering approach for ad hoc sensor networks

    Publication Year: 2004 , Page(s): 366 - 379
    Cited by:  Papers (964)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (880 KB) |  | HTML iconHTML  

    Topology control in a sensor network balances load on sensor nodes and increases network scalability and lifetime. Clustering sensor nodes is an effective topology control approach. We propose a novel distributed clustering approach for long-lived ad hoc sensor networks. Our proposed approach does not make any assumptions about the presence of infrastructure or about node capabilities, other than the availability of multiple power levels in sensor nodes. We present a protocol, HEED (Hybrid Energy-Efficient Distributed clustering), that periodically selects cluster heads according to a hybrid of the node residual energy and a secondary parameter, such as node proximity to its neighbors or node degree. HEED terminates in O(1) iterations, incurs low message overhead, and achieves fairly uniform cluster head distribution across the network. We prove that, with appropriate bounds on node density and intracluster and intercluster transmission ranges, HEED can asymptotically almost surely guarantee connectivity of clustered networks. Simulation results demonstrate that our proposed approach is effective in prolonging the network lifetime and supporting scalable data aggregation. View full abstract»

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  • Courtesy piggybacking: supporting differentiated services in multihop mobile ad hoc networks

    Publication Year: 2004 , Page(s): 380 - 393
    Cited by:  Papers (5)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1040 KB) |  | HTML iconHTML  

    Due to the salient characteristics such as the time-varying and error-prone wireless links, the dynamic and limited bandwidth, the time-varying traffic pattern and user locations, and the energy constraints, it is a challenging task to efficiently support heterogeneous traffic with different quality of service (CoS) requirements in multihop mobile ad hoc networks. In the last few years, many channel-dependent mechanisms are proposed to address this issue based on the cross-layer design philosophy. However, a lot of problems remain before more efficient solutions are found. One of the problems is how to alleviate the conflict between throughput and fairness for different prioritized traffic, especially how to avoid the bandwidth starvation problem for low-priority traffic when the high-priority traffic load is very high. In this paper, we propose a novel scheme named Courtesy Piggybacking to address this problem. With the recognition of interlayer coupling, our Courtesy Piggybacking scheme exploits the channel dynamics and stochastic traffic features to alleviate the conflict. The basic idea is to let the high-priority traffic help the low-priority traffic by sharing unused residual bandwidth with courtesy. Another noteworthy feature of the proposed scheme is its implementation simplicity: The scheme is easy to implement and is applicable in networks using either reservation-based or contention-based MAC protocols. View full abstract»

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  • Efficient dissemination of personalized information using content-based multicast

    Publication Year: 2004 , Page(s): 394 - 408
    Cited by:  Papers (3)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (952 KB) |  | HTML iconHTML  

    There has been a surge of interest in the delivery of personalized information to users (e.g., personalized stocks or travel information), particularly as mobile users with limited terminal device capabilities increasingly desire updated and targeted information in real time. When the number of information recipients is large and there is sufficient commonality in their interests, as is often the case, IP multicast is an efficient way of delivering the information. However, IP multicast services do not consider the structure and semantics of the information in the multicast process. We propose the use of Content-Based Multicast (CBM) where extra content filtering is performed at the interior nodes of the IP multicast tree; this will reduce network bandwidth usage and delivery delay, as well as the computation required at the sources and sinks. We evaluate the situations in which CBM is advantageous. The benefits of CBM depend critically upon how well filters are placed at interior nodes of the IP multicast tree and the costs depend upon those introduced by filters themselves. Further, we consider the benefits of allowing the filters to be mobile so as to respond to user mobility or changes in user interests and the corresponding costs of filter mobility. The criterion that we consider is the total network bandwidth utilization. For this criterion, we develop an optimal filter placement algorithm, as well as a heuristic that executes faster than the optimal algorithm. We evaluate the algorithms by means of simulation experiments. Our results indicate that filters can be effective in substantially reducing bandwidth. We also find filter mobility is worthwhile if there is marked large-scale user mobility. We conclude with suggestions for further work. View full abstract»

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  • Annual Index

    Publication Year: 2004 , Page(s): 409 - 413
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  • [Advertisement]

    Publication Year: 2004 , Page(s): 414
    Cited by:  Papers (1)
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  • [Advertisement]

    Publication Year: 2004 , Page(s): 415
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  • [Advertisement]

    Publication Year: 2004 , Page(s): 416
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  • TMC Information for authors

    Publication Year: 2004 , Page(s): c3
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  • [Back cover]

    Publication Year: 2004 , 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