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Applications and Services in Wireless Networks, 2004. ASWN 2004. 2004 4th Workshop on

Date 9-11 Aug. 2004

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  • 2004 4th Workshop on Applications and Services in Wireless Networks (ASWN)

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    Freely Available from IEEE
  • [Breaker page]

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  • 2004 4th Workshop on Applications and Services in Wireless Networks (ASWN)

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  • Copyright page

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  • Welcome

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  • Committees

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  • Table of contents

    Page(s): v - vi
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  • Searching strategy for multi-target discovery in wireless networks

    Page(s): 1 - 10
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1839 KB) |  | HTML iconHTML  

    In this paper, we address a fundamental problem concerning the optimal searching strategy in terms of searching cost for the multi-target discovery problem in wireless networks. In order to find the nearest k targets from a total of m members with the least cost , how many searching attempts should we use, and how large should each searching area be? After providing the applications that motivate our research, we model the problem and derive a general formula for the expected cost as a function of the parameters of the number of searching attempts n and the searching area for each attempt, Ai. Based on this formula, we propose several algorithms to determine the optimal parameters to achieve the minimal cost, either pre-calculated or performed online. Using the optimal parameters derived from analysis, we experiment with these algorithms on general wireless network scenarios. The results show that our algorithms perform consistently close to optimal, and they exhibit much better performance than other heuristic schemes. The desired performance is achieved by adapting the searching radius to estimates of network parameters such as the total number of nodes and the total number of targets. View full abstract»

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  • Using behavior templates to design remotely executing agents for wireless clients

    Page(s): 11 - 20
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2355 KB) |  | HTML iconHTML  

    ReAgents are remotely executing agents derived from behavior templates that support wireless clients in Internet applications. A reAgent is essentially a "one-shot" mobile agent that acts as an extension of a client, dynamically launched by the client to run on its behalf at a remote, more advantageous, location. Templates simplify the programming of reAgents by transparently handling data migration for remote execution, supporting custom communication protocols between the client and agent, and providing a general interface for programmers to implement their application-specific customizing logic. This simplification is made possible by the identification of characteristic behaviors, i.e., common patterns of actions that exploit the ability to process and communicate remotely. Examples of such behaviors are filtering, encoding/decoding, monitoring, caching, and distribution/collation. In this paper, we identify and analyze a set of core characteristic behaviors, describe how to program reAgents using behavior templates, and show that the overhead of using reAgents is low and outweighed by its benefits. View full abstract»

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  • Replicated client-server execution to overcome unpredictability in mobile environment

    Page(s): 21 - 29
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1490 KB) |  | HTML iconHTML  

    This paper examines the fundamental limitation of adaptation based methods in the presence of unpredictability and instability in wireless network bandwidth, server loads, and usage patterns. We argue that existing adaptation based methods may fail to produce good application response time given such unpredictability and instability, because they require somehow accurate prediction on resource conditions and usage patterns in order to perform effectively. We have designed and implemented a new, simple yet powerful, replicated client-server model which overcomes this fundamental problem of unpredictability and instability. The basic idea behind replicated client-server model is simple - application execution is replicated on both client and server, and the faster result is returned to the user. It provides the benefit of faster response time at the cost of computational overhead in replicating executions on both client and server. View full abstract»

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  • Resource-controlled remote execution to enhance wireless network applications

    Page(s): 30 - 38
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1730 KB) |  | HTML iconHTML  

    We present the design and implementation of a system that provides resource-controlled execution environments for client and server application functionality. The system supports a remote execution model that "extends" a client or server endpoint by allowing either to insert functionality at a point along the communication path between the two endpoints. This is especially useful for wireless clients, as resource limited clients can take advantage of nearby processing power, and for clients that access the Internet via a fast wireless LAN, servers can move services close to the base station to reduce latency and improve bandwidth. The system operates entirely at user-level and so is easily deployable, and it supports quality of service in the form of rate-based resource reservations. View full abstract»

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  • EAP-TLS smarteards, from dream to reality

    Page(s): 39 - 45
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1245 KB) |  | HTML iconHTML  

    This paper presents the first implementation of the EAPTLS (Extensible Authentication Protocol-Transport Layer Security) protocol in smartcards. Tests, performed on two java devices, are discussed and analysed. Results show that TLS processing is slow, because smartcards are not (yet) optimized for that purpose; however we clearly demonstrate that TLS processing in smartcards is not today a dream, and can be realized with existing components. View full abstract»

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  • Enabling secure third party control on wireless home networks

    Page(s): 46 - 54
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1435 KB) |  | HTML iconHTML  

    Running a home network gives one the ability to share different services, not only among the devices that are part of the network in his/her home, but also to distant entities. This latter feature requires an efficient security architecture to secure the remote access. In this article, we consider the scenario where an operator requires access to a home network device to get profit from a service or to update its configuration through a residential gateway. View full abstract»

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  • A lightweight statistical authentication protocol for access control in wireless LANs

    Page(s): 55 - 64
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1769 KB) |  | HTML iconHTML  

    With the increasing performance and dropping price of wireless networking equipments, wireless networking has revolutionized the way people work and play. Wi-Fi hot spots popping up all over the country provides a convenient way of internet connectivity. For the ISPs of hot spots, authentication and accounting have been recognized as two most crucial concerns. For authentication, IETF PANA 1 WG, is working on a transport protocol for authenticating IP hosts for network access. However, PANA does not provide access control and per-packet authentication, which are desirable in accounting and access control. Instead of using high-overhead crypto-based mechanisms, such as IPSec or 802.11i, we propose a lightweight statistical authentication protocol, namely Shepherd2. In Shepherd, the legitimacy of a mobile node is determined by continuously checking a series of random authentication bits where each hit in this stream is piggybacked by a packet. Such authentication bit stream is generated by both mobile node and access point using the same random number generator under the same shared seed as a key. We analyze this protocol under three synchronization schemes. Our analytical results show that this protocol performs well in terms of computational and communication cost, synchronization efficiency, and protocol operation secrecy. We also show that this new protocol is practical for implementation in wireless LANs. View full abstract»

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  • Liveliness evaluation of a cooperation and accounting strategy in hybrid networks

    Page(s): 65 - 71
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (918 KB) |  | HTML iconHTML  

    We propose a cooperation and accounting scheme for multi-hop cellular networks, which stimulates cooperation among nodes by making it a rewarding alternative to selfishness. The paper describes an architecture with highly decentralized security and accounting mechanisms. Our scheme charges senders and rewards forwarders, supports both sender- and receiver-based payments and coexists with ad hoc oo1y traffic. We use of service stations deployed throughout the network to offer nodes a possibility to refill their money accounts. We present the results of simulation runs, where we investigated the liveliness of the proposed scheme. We find that the number of service stations and their distribution correlate in different ways. View full abstract»

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  • Evaluation of 802.11a for streaming data in ad-hoc networks

    Page(s): 72 - 81
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1439 KB) |  | HTML iconHTML  

    Advances in communication and processing have made ad-hoc networks of wireless devices a reality. One application is home entertainment systems where multiple Home-to-Home (H20) devices collaborate as peers to stream audio and video clips to a household. In this study, we investigate the feasibility of IEEE 802.11a protocol in combination with both TCP and UDP to realize a H20 device. Challenges include lossy connections, unfair allocation of bandwidth between multiple simultaneous transmissions, and the exposed node limitation [22], [19], [13], [4]. Our primary contribution is an empirical study of 802.11a to quantify these factors and their significance. Our multi-dimensional experimental design consists of the following axes: distance between participating devices, number of intermediate H20 devices used to route a stream from a producing H20 device to a consuming H2O device, and simultaneous number of active streams in the same radio range. Both operating system and application level routing were considered_ Obtained results demonstrate the following lessons. First, with a multi-hop UDP transmission, in the absence of congestion control, transient bottlenecks result in a high loss rate. Hence, a transport protocol with congestion control is essential for streaming of continuous media within a H2O cloud. Second, 802.11a does not drop TCP connections in the presence of many competing transmissions (802.11b drops connections [22]). Third, we observed fairness when transmitting several hundred Megabytes (MB) of data, among multiple competing 1- hop TCP and UDP flows. Fourth, while there is unfair allocation of bandwidth with an exposed node, the observed bandwidths are sufficient to stream a high-quality video clip (with a 4 Mbps display bandwidth requirement). These results indicate streaming of data is feasible with an ad-hoc network of wireless devices employing the 80211a protocol. View full abstract»

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  • Enhancing IEEE 802.11 MAC in congested environments

    Page(s): 82 - 91
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1795 KB) |  | HTML iconHTML  

    IEEE 802.11 is the most deployed wireless local area networking standard nowadays. It uses carrier sense multiple access with collision avoidance (CSMA/CA) to resolve contention between nodes. Contention windows (CW) change dynamically to adapt to the contention level: Upon each collision, a node doubles its CW to reduce further collision risks. Upon a successful transmission, the CW is reset, assuming that the contention level has dropped. However, contention level is more likely to change slowly, and resetting the CW causes new collisions and retransmissions before reaching the optimal value again. This wastes bandwidth and increases delays. In this paper we analyze simple slow CW decrease functions and compare their performances to the legacy standard. We use simulations and mathematical modeling to show their considerable improvements at all contention levels and transient phases, especially in high congested environments. View full abstract»

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  • Performance evaluation of 3G CDMA networks with antenna arrays

    Page(s): 92 - 98
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (960 KB) |  | HTML iconHTML  

    The 2G CDMA IS-95A cellular network has been deployed for almost eight yean. Although the system design rules and operating procedures for voice services are well established and understood, these rules and procedures need to be re-examined in light of several technology innovations. These innovations include the launch of cdma2000 1x high-rate data services and the new research results in interference cancellation, antenna array and multiple-input multiple-output (MIMO) technologies. We have built a 3G cdma2000 1x cellular simulator, which simulates the physical layer using MATLAB and networking layers using OPNET Modeler, to investigate various design issues of cdma2000 1x networks. In this paper, we investigate the effectiveness of deploying antenna array techniques in CDMA networks using cdma2000 1x cellular simulator. We evaluate the capacity improvement for CDMA networks using antenna array technique under different deployment scenarios. We propose to utilize antenna array as one of the elements in QOS provisioning for data services. We also propose to couple antenna array with dynamic soft hand off thresholds adjustment to further improve the system capacity. View full abstract»

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  • Design and evaluation of scalable ubiquitous discovery system

    Page(s): 125 - 131
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1304 KB) |  | HTML iconHTML  

    Some future advanced applications such as contextaware communication and object status tracing require a mechanism to collect detailed sensor data from the real world and distribuite it in real time. This paper describes design of SUDS (Scalable Ubiquitous Discovery System) which adopts flat ID management so that an end user can flexibly assign unique IDs to objects. Though previous P2P protocols are appropriate for discovery of IDs that have flat architecture, peers in mobile network suffer from frequent routing table update. Previous protocols triger unnecessary routing table update whenever a node is disconnected from the network, because a temporarily disconnected peer is regarded as a peer that leaves the P2P network. We propose a wireless-aware P2P protocol for SUDS, which assures responsiveness against temporal network disconnection by multiple path function instead of pruning the disconnected peer away from the P2P network. The proposed protocol is implemented and evaluation results show that the multiple path routing function is effective for the realtime discovery of information with an acceptable increase in network traffic. View full abstract»

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  • Allowing errors in speech over wireless LANs

    Page(s): 142 - 151
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1681 KB) |  | HTML iconHTML  

    Wireless LANs are becoming commonplace because of their ease in providing mobile communication. As use of IEEE 802.11 continues to expand, support for voice will become a desirable feature. Supporting voice conversations over a packet network is more challenging than over current circuit switched wired networks. These challenges are particularly difficult due to the erroneous nature of a wireless channel. When errors occur in data packets the IEEE 802.11 MAC layer standard requires that the receiver not accept the packet; the source must retransmit all packets received with errors. However, digitized voice data can tolerate some error and loss without noticeable degradation in call qUality. By forcing error-free reception of speech, scarce bandwidth and energy are unnecessarily expended, and the delay of the packets increases. In this paper we explore allowing bit errors in voice packets over IEEE 802.11 networks. We propose two strategies for allowing these errors and demonstrate that they both result in improved perfonnance. View full abstract»

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