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Communication Systems and Networks and Workshops, 2009. COMSNETS 2009. First International

Date 5-10 Jan. 2009

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Displaying Results 1 - 25 of 92
  • Community formation and search in P2P: A robust and self-adjusting algorithm

    Page(s): 1 - 8
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 KB) |  | HTML iconHTML  

    The existing literature deals with the problems dealing with decentralized content-based P2P community formation and community-based search separately. Contrary to this approach, in this paper we propose a novel search algorithm that has both the capability to form the community structure as well as search it with maximum efficiency. The key contribution is to design a self-organized and adaptive search algorithm where as the community topology evolves with time, the search process adapts automatically to the situation to provide best performance. It performs an automatic transition from the exploratory phase to search phase, by estimating the global state of communities using a local control parameter. Moreover, we show that the strategy is also robust enough to improve search performance even under node churn, though a graceful degradation in overall performance is seen. We consider realistic power-law distribution for node degrees and information profiles. The proposed search strategy shows more than twice efficiency than a pure random walk with proliferation on the same network. View full abstract»

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  • Resource adaptive hierarchical organization in pervasive environments

    Page(s): 1 - 8
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3046 KB) |  | HTML iconHTML  

    Pervasive computing environments are characterized with an array of heterogeneous devices. Within such environments, it is necessary to accommodate devices with restrictions on available resources through cooperation of devices that have greater resource availability. Traditionally, such cooperation is achieved based on information available prior to operation, resulting in a rigid structure that cannot change during runtime. In this paper, we present a generic framework aimed at achieving a dynamic, hierarchical overlay of devices based on their resource availability. We consider the processing power, memory and battery power, on each device as the dynamically changing resources. Based on the proposed Availability metric, a hierarchical overlay structure is developed among the available devices. Devices in the lower layers of the hierarchy seek operational support from those in the higher layers which are relatively more resourceful. The resulting hierarchical organization is utilized to provide support for service composition and management. The proposed adaptive mechanism allows dynamic restructuring of the hierarchy based on changes in the availability of resources. In addition, the adaptive hierarchical organization results in enhanced longevity of resources and increased availability of services to applications. The performance improvements achieved through the dynamic resource organization are demonstrated through experimental results. View full abstract»

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  • A framework for application centric wireless sensor network management

    Page(s): 1 - 7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2788 KB) |  | HTML iconHTML  

    We propose a wireless sensor network management framework where we consider the management activity as a meta level thread of computation that monitors the lower (object) level protocol related thread of computations and performs management actions to affect the lower level computations. While the protocols perform the object level computations, the management level computations are performed by a set of rules. In this framework, the wireless network management can not only be tuned for specific applications, but also can be driven by flexible management policies, which can be coded explicitly in the implementation. View full abstract»

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  • Handoff mechanism in MPLS enabled wireless network

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (279 KB) |  | HTML iconHTML  

    In this paper, we propose a layered MPLS based mobility solution to support mobility in seamless manner. This scheme uses an enhanced type of MPLS router called label edge mobility agent (LEMA), takes an active part in mobility management. To support fast and dynamic handoff an intelligent multicasting method is discussed that shows good performance in handoff latency and packet loss. The analytical results show a remarkable network performance in terms of reducing location update, handoff delay, packet loss and buffer size. We compare our result with other MIP based protocols like MIPv4 and H-MPLS. View full abstract»

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  • Design of efficient ternary-tree based group key agreement protocol for dynamic groups

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1013 KB) |  | HTML iconHTML  

    Several groupware applications such as distributed databases, video conferences, distributed computation etc require secure transmission while communicating over open connected networks, and for which numerous group key agreement protocols for static/dynamic groups have been proposed for establishing a secret session key among the group members. This paper proposes ternary tree based new technique to establish a contributory secure group key for dynamic groups, where a ternary tree has at most three children per node. The proposed technique instead of using two-party Diffie-Hellman technique as used in most of the binary tree based group-key generation techniques, uses an existing three party key exchange technique called GDH.2 to establish a shared secret key between the participants. The method provides some advantages over the existing binary tree based technique as it reduces the number of iterations to log3N, where N is the number of participants, covers larger subgroup using broadcast messages than subgroup formed in binary tree based approaches etc. As a result, the total number of broadcast messages and the exponential operations are reduced and it becomes a communication and computation efficient group key agreement protocol. Since proposed technique is projected for dynamic groups, therefore after initialization operation, the method describes and calculates the complexity of major group key management operations like single join, mass join and mass leave. The results obtained are then compared with other efficient group key agreement protocols like CCEGK, EGK, TGDH, STR and it has been seen that proposed method in most of the cases performs well. View full abstract»

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  • Prevention of denial of service attacks and performance enhancement in Mobile Adhoc networks

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (245 KB) |  | HTML iconHTML  

    A mobile ad hoc network is a network without any infrastructure or service access points. In wireless ad hoc networks, the performance of the media access control (MAC) protocol has significant impact on the overall network performance. In contention-based MAC protocols, nodes' access to the shared channel is not synchronized, and they contend for the channel whenever there are packets in their buffers ready to be sent. To reduce self-contention, Fast-forward mechanism and quick exchange mechanism are being used. But these mechanisms aggravate the fairness problem, because the node that succeeds in the last transmission period will gain access to the shared channel again with much higher probability while other nodes are denied access almost completely. Thus it will lead to denial of service attacks because the last winner is always favored among local contending nodes, a continuously transmitting node can always capture the channel and cause other nodes to back off endlessly. Simulation results also reveal the fairness problem in ad hoc networks refers to the severe degradation in throughput. Here, a DoSP-MAC protocol is proposed to improve the fairness of the network thereby enhance its performance. This can drastically improve the medium utilization. View full abstract»

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  • Bandwidth measurement and management for end-to-end connectivity over IP networks

    Page(s): 1 - 8
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (355 KB) |  | HTML iconHTML  

    The paper describes a policy-based model for cost-effective dasiadata connectivitypsila provisioning between session-level end-points. The connectivity provider (SP) may employ an architecture for end-to-end QoS control between data aggregation points. It involves: i) maintaining multiple diffserv-type connections between end-points with parameterizable QoS differentiation between them; and ii) admission control at end-points with intserv-type bandwidth management over connections. (ii) aggregates data flows with closely-similar QoS needs over a single end-to-end connection. (i) apportions the available infrastructure bandwidth between various end-to-end connections that carry (aggregated) data flows with distinct QoS levels. Flow aggregation over a connection allows reaping the statistical multiplexing gains in bandwidth, i.e., meets the SP's revenue incentives. Whereas, connection-level bandwidth allocation allows meeting the QoS needs of data flows, i.e., guarantees the end-user's utility. The management functions of SP monitor the changes and/or outages in network bandwidth in a dynamic setting (as in IP-based networks), and maps them onto the connectivity costs incurred for QoS control. Our model allows installing policy functions at end-points for cost-optimal connectivity provisioning. View full abstract»

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  • Control-theoretic, mission-driven, optimization techniques for wireless sensor networks

    Page(s): 1 - 8
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2623 KB) |  | HTML iconHTML  

    Network Utility Maximization (NUM) techniques, which cast resource sharing problems as one of distributed utility maximization, have been investigated for a variety of optimization problems in wireless and wired networks. Our recent work has extended the NUM framework to consider the case of resource sharing by multiple competing missions in a military-centric wireless sensor network (WSN) environment. Our enhanced NUM-based protocols provide rapid and dynamic mission-based adaptation of tactical wireless networks to support the transport of sensor data streams with very small control overhead. In particular, we focus specifically on mechanisms that capture the joint nature of mission utilities and the presence of prioritized mission demands. We then introduce a new problem, of joint utility and network lifetime maximization, as a representative of a new class of multi-metric optimization problems, and provide early evidence that techniques from optimal control theory can be used to derive distributed adaptation protocols conforming to the basic NUM paradigm. We also enumerate and motivate a list of open cross-layer dynamic adaptation problems of direct relevance to military C4I operations. View full abstract»

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  • A greedy minimum energy consumption forwarding protocol for wireless sensor networks

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (250 KB) |  | HTML iconHTML  

    Energy consumption is a vital resource to be controlled to extend the longevity of a wireless sensor network. In a multihop routing, lifetime as well as throughput of the network could be increased by selecting the forwarding node intelligently. The existing energy-aware routing protocols either do not jointly consider the network performance and energy saving, or they are not distributed. In this paper, we propose an efficient greedy forwarding protocol, called minimum energy consumption forwarding, which selects a forwarding node on the basis of minimum transmit and receive energy consumption per successful packet transmission per unit Euclidean distance progress toward the destination, in a distributed fashion. In the proposed algorithm, at each hop the forwarding decision can be either taken by the transmitter at each forwarding node or the best forwarder can be elected by some kind of election contention mechanism. Through network simulations we have shown that the proposed energy consumption minimizing distributed forwarding strategy outperforms the greedy geographic forwarding algorithm in terms of increasing the network lifetime and end-to-end throughput. The proposed algorithm can be easily retrofitted in the already developed network capable wireless sensor nodes. View full abstract»

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  • Genetic Algorithm approach to Dynamic Multi Constraint Multi Path QoS Routing Algorithm for IP networks (GA-DMCMPRA)

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (514 KB) |  | HTML iconHTML  

    Real-time distributed multimedia applications have special requirements in terms of bandwidth, delay, delay jitter, etc. The current network, essentially being a connection-less network, provides only un-reliable, best-effort service. The data packets may follow different paths to the destination. The network resources, viz., switch buffer and link bandwidth, are fairly shared by packets from different sessions. This type of network is best suitable for applications such as email, ftp, etc., but not suitable for real time multimedia applications such as video-on-demand, video conferencing, Internet telephony, etc., as these applications require different QoS requirements from the underlying network. In order to make the network suitable for such applications many QoS routing algorithms have been proposed. The problem of finding a path with multiple constraints is a NP-complete problem. Hence, various heuristics have been proposed to find a path that satisfies more than one constraint. All these heuristics do not consider the queuing situation at a given node. An alternate path with less queue occupancy may be more convenient to use than the optimum path when a long queue is present in nodes along the path. To search all feasible paths in less time, many researchers have used the concept of Genetic Algorithm (GA), which is a new computational strategy inspired by natural processes.This GA approach has been used in the existing Dynamic Multi Constraint Multi Path QoS Routing Algorithm (DMCMPRA) [23] for IP networks to find k feasible paths satisfying the multi constraint requirement of the multi media applications. Computer simulations show that GA-DMCMPRA takes less time for path computation when compared to Dynamic Multi Constraint Multi Path QoS Routing Algorithm (DMCMPRA). Further it is also proved that the performance of GA-DMCMPRA with respect to percentage of Packets received and average Delay experienced by packets is at par with DMCMPRA. View full abstract»

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  • Integration of macro and micro mobility protocols

    Page(s): 1 - 7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (193 KB) |  | HTML iconHTML  

    The success of next generation wireless networks will rely much on advanced mechanisms for seamless mobility support among emerging heterogeneous technologies. Currently, mobile IP is the most promising solution for mobility management in the Internet. Several IP micro mobility approaches have been proposed to enhance the performance of mobile IP which supports quality of service, minimum packet loss, limited handoff delay and scalability and power conservation but they are not scalable for macro mobility. A practical solution would therefore require integration of mobile IP and micro mobility protocols where mobile IP handles macro mobility and HMIP, cellular IP, HAWAII handles micro mobility. In this paper an integrated mobility management protocol for IP based wireless networks is proposed and analyzed. Simulation results presented in this paper are based on ns 2. View full abstract»

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  • Efficient flow-aware dynamic link load balancing

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (226 KB) |  | HTML iconHTML  

    Link Load balancing and serves as a useful abstraction for achieving bandwidth aggregation by means of aggregating multiple physical links into a single logical link. It is a key component of traffic engineering, link aggregation, and equal cost multi-path routing. Dynamic link load balancing needs schemes that dynamically distribute traffic across multiple paths at a fine granularity without disrupting the packet flows. This distribution should be fair in terms traffic distribution and link usage to ensure effective utilization of the available link capacity. Existing solutions exhibit a tussle between their efficiency in distributing flows uniformly across the links and their ability to avoid packet reordering within a flow. This paper examines the inadequacies and limitations manifested in the existing solutions and introduce a new scalable dynamic load balancing scheme that guarantees with a very high and programmable probability that the heavily loaded link is never assigned a new flow. The proposed method also guarantees that the packets belonging to a flow are never distributed among the links, thus avoiding reordering and packet loss. View full abstract»

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  • Performance Comparison of Mobile IPv4 and Mobile IPv6 protocols in wireless systems

    Page(s): 1 - 8
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (246 KB) |  | HTML iconHTML  

    The success of next generation wireless networks will rely much on advanced mechanisms for seamless mobility support among emerging heterogeneous technologies. Currently, Mobile IPv4 is the most promising solution for mobility management in the Internet but it suffers from certain problems. Mobile IPv6 are designed for the next generation wireless networks and it overcomes the problems of MIPv4. The integration of mobile cellphones with Internet-based multimedia services will force a move to the next generation version of IP (IPv6). In order to apply Mobile IP in current internet environments, the TCP performance of MIPv4 and MIPv6 is evaluated and compared in this paper. Simulation results presented in this paper are based on ns 2. View full abstract»

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  • An architecture for self-configuration of network for QoS and security

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (335 KB) |  | HTML iconHTML  

    We present an architecture for self-configuration of network entities for QoS and Security, based on the health of the network. In the architecture, we firstly present a novel data collection mechanism that integrates various network inputs such as flow data, packet data and SNMP values. Secondly we present our analysis of these inputs based on QoS and Security aspects and discuss analysis mechanisms that generates dynamic scripts leading to self-configuration of the decisions arrived. Finally we explain the response engine that carries out the automatic configuration of network devices based on the directives provided by the analysis engine. Traditionally, network configurations are static and are carried out manually after monitoring the network statistics or based on demand. Our architecture is a step towards evolving dynamic self-configurations of networks by creating self-awareness within a network. View full abstract»

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  • Analytical framework for the performance assessment of the strategies for integrating Mobile Ad Hoc Networks and the Internet

    Page(s): 1 - 8
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (380 KB) |  | HTML iconHTML  

    Many strategies have been proposed for integrating mobile ad hoc networks and the Internet. A need has been felt for an analytical framework that would facilitate a formal definition and comparison of different integration strategies without actually implementing them in a simulated environment. In this paper, we present an analytical framework based on the concept of a relay path (RP). This model can be used to describe, compare the different strategies for integrating mobile ad hoc networks and the Internet, propose new strategies and improve the existing strategies at different module levels. The proposed analytical model has been simulated on a few integration strategies. Presently, only the mobile IP overhead is being estimated with this model. View full abstract»

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  • A novel real time voice quality testing model for VoIP ambience environment in wireless LAN

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (283 KB) |  | HTML iconHTML  

    This in this work, we propose a model for measuring and improving voice quality under ambience environment for VoIP calls in wireless WLAN 802.11. Existing models such as E-model, PESQ model and Adaptive model which address QoS in VoIP networking do not address voice quality management in real time environment to improve voice quality. The idea is to use background noise and its associated source information in an adaptive environment to boost user perceivance audio level thereby quality is assured. This issue is important because in real time, consumers might be interested with mobiles that address ambience effect to determine human audible effect based on environment conditions. The set-up include environment noise detector to assimilate environment noise level and adaptive audio factor manager to tune audio level accordingly. Then QoS factor is determined for this set-up. Further, according to our model, when dB level increases, audio level at receiver side is tuned adaptively at that point of time by decision manager thereby providing better QoI metric under ambience environment. View full abstract»

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  • Social networking and context management for the future 3D Internet

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (471 KB) |  | HTML iconHTML  

    Current trends in 3D visualization merged with internet applications and sensor technologies will soon break the barriers to the widespread acceptance of 3D Internet, and they will enable a full user immersion in the virtual world. However this evolution will impact dramatically on the existing infrastructures since the fruition of 3D content in real time by a huge number of people poses new issues related to the system responsiveness and to the ability of managing context information. In this paper we observe that actions related to the acquisition of context from the physical and from the virtual worlds, as well as actuation in both worlds can be considered as a special case of context management and actuation. For this reason we propose an architecture for the management of such aspects within a unique framework, and an experimental testbed that validates the architecture. View full abstract»

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  • Avoiding white washing in P2P networks

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2094 KB) |  | HTML iconHTML  

    Peer-to-peer (P2P) networks provide a decentralized way of sharing resources. In an unsolicited network the peers have too less incentive to behave honestly. To avoid tragedy of commons some sort of an incentive mechanism has to be introduced. Reputation systems provide a good solution for this problem. In a reputation system boot strapping remains a problem. In systems where pseudonyms are cheap (i.e. a peer can enter and get an id and establish itself for a ldquocheaprdquo cost) white washing becomes a problem. Whereas systems with ldquocostlyrdquo pseudonyms become highly prohibitive for new entrants thereby reducing the scalability of the system. In this paper, we propose a mechanism for acquiring pseudonyms so as to avoid white washing while maintaining low entry barriers for new comers. View full abstract»

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  • Automatic extraction of highlights from a cricket video using MPEG-7 descriptors

    Page(s): 1 - 3
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (170 KB) |  | HTML iconHTML  

    Sports videos appeal to a vast majority of people. Hence, video streaming of sports videos presents a profitable business opportunity. As a result, there is an astronomical increase in the amount of sports content available on the internet. Businesses and users face a new problem of perusing such large amounts of multimedia content quickly for the required information. One technique that can enable quick overview of multimedia content is video summarization. In this paper, an approach to summarize a cricket game video by using highlights extraction process is presented. The video is first segmented into shots. Key frames are extracted from each shot and low level features are extracted from the key frames. Feature are used to extract views or states. The states and their transitions in the cricket game are represented by a Hidden Markov Model, based on which the game highlights are extracted. The performance of the proposed summarization scheme is evaluated for accuracy. View full abstract»

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  • An IPTV service model for the multi-world

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (277 KB) |  | HTML iconHTML  

    Technology trends indicate that in the Internet world, video content gets created, delivered, consumed rather differently compared to the traditional broadcast TV. This necessitates the next gen IPTV systems to incorporate capabilities for addressing the needs of these emerging markets, to satisfy both the service provider and the service consumer effectively. Trends bring out a ldquomultirdquo factor that is emerging vividly to suit the needs of this new consumer - be it with respect to the multiple service providers depending on the content of choice at a given point of time, or the multiple devices being used for consumption of this content at any given location, or the interaction models with these devices depending on the capabilities, and so on. In this paper we propose a service model to address these various factors. View full abstract»

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  • Opportunistic sensing: Security challenges for the new paradigm

    Page(s): 1 - 10
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (130 KB) |  | HTML iconHTML  

    We study the security challenges that arise in opportunistic people-centric sensing, a new sensing paradigm leveraging humans as part of the sensing infrastructure. Most prior sensor-network research has focused on collecting and processing environmental data using a static topology and an application-aware infrastructure, whereas opportunistic sensing involves collecting, storing, processing and fusing large volumes of data related to everyday human activities. This highly dynamic and mobile setting, where humans are the central focus, presents new challenges for information security, because data originates from sensors carried by people - not tiny sensors thrown in the forest or attached to animals. In this paper we aim to instigate discussion of this critical issue, because opportunistic people-centric sensing will never succeed without adequate provisions for security and privacy. To that end, we outline several important challenges and suggest general solutions that hold promise in this new sensing paradigm. View full abstract»

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  • Length-based anchor-free localization in a fully covered sensor network

    Page(s): 1 - 10
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4214 KB) |  | HTML iconHTML  

    Localization is an important issue for Wireless Sensor Networks (WSN). We consider a WSN consisting of identical sensors. All known distances between the sensors are assumed to be less than the communication range of the sensors and all unknown distances greater. We also assume that the communication range is at least twice as much as the sensing range. Every point in the field of interest is assumed to be within the sensing zone of some sensor. Under this model, we propose an anchor-free length-based localization algorithm. The worst case time complexity of the algorithm is O(|E|) (where E is the set of edges of the network graph). We carry out simulation studies to observe that under uniform distribution, the number of edges is actually much lower than n2, if just about enough sensors are deployed to cover the total field. We prove that, under this model, the solution to the localization problem is unique. We also provide a simple technique for verifying the assumption that all points in the field are covered. View full abstract»

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  • Mathematical analysis of sensor fusion for intrusion detection systems

    Page(s): 1 - 10
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2752 KB) |  | HTML iconHTML  

    Fusion of multiple intrusion detection systems results in a more reliable and accurate detection for a wider class of intrusions. The paper presented here introduces the mathematical basis for sensor fusion and provides enough support for the acceptability of sensor fusion in performance enhancement of intrusion detection systems. The sensor fusion system is characterized and modeled with no knowledge of the intrusion detection systems and the intrusion detection data. The theoretical analysis is supported with an experimental illustration with three of the available intrusion detection systems using the DARPA 1999 evaluation data set. View full abstract»

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  • Metronome: Coordinating spectrum sharing in heterogeneous wireless networks

    Page(s): 1 - 10
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3997 KB) |  | HTML iconHTML  

    Many licensed and unlicensed frequency bands support heterogeneous wireless networks running different physical and link layer protocols. These networks ldquosharerdquo spectrum, but in an anarchic and arbitrary manner, resulting in poor performance for some networks and sub-optimal performance in aggregate. This problem is likely to be of importance in the US 700 MHz TV band, which is being explored for secondary use. This paper describes Metronome, a system that allows heterogeneous networks to coexist well. Metronome provides a flexible and expressive policy language that allows a network operator to specify constraints on receiver performance metrics such as throughput or loss rates. Metronome then configures each participating transmitter with appropriate channel, bandwidth, and transmission power settings automatically. Experiments from an outdoor vehicular platform for monitoring the TV band, and from an indoor heterogeneous network of 802.11, ZigBee and Bluetooth devices demonstrate the utility of Metronome's policy language. In a network of coexisting devices, we find that Metronome improves the throughputs of ZigBee and Bluetooth by more than 6times and that of 802.11 by more than 15%. View full abstract»

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  • Dummy tone insertion for spectral sculpting of the multi-band OFDM UWB system

    Page(s): 1 - 7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4220 KB) |  | HTML iconHTML  

    As the UWB regulations have not been finalized in many parts of the world, spectral flexibility is a key requirement for an UWB system to win in the global marketplace. The unlicensed nature of the UWB spectrum makes it imperative for these devices to have the capability to coexist with existing services. The multi-band OFDM UWB communication system, standardized by ECMA for high-speed WPAN, has the ability to satisfy these requirements. This paper describes a time-domain windowing technique and a dummy tone insertion mechanism that enable spectral sculpting of a multi-band OFDM UWB communication system. The protection offered to radio astronomy bands in Japan is used as an example to illustrate the advantages of these techniques. View full abstract»

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