Showing papers on "Heterogeneous network published in 2003"

On the capacity of hybrid wireless networks

Abstract: This paper involves the study of the throughput capacity of hybrid wireless networks. A hybrid network is formed by placing a sparse network of base stations in an ad hoc network. These base stations are assumed to be connected by a high-bandwidth wired network and act as relays for wireless nodes. They are not data sources nor data receivers. Hybrid networks present a tradeoff between traditional cellular networks and pure ad hoc networks in that data may be forwarded in a multihop fashion or through the infrastructure. It has been shown that the capacity of a random ad hoc network does not scale well with the number of nodes in the system. In this work, we consider two different routing strategies and study the scaling behavior of the throughput capacity of a hybrid network. Analytical expressions of the throughput capacity are obtained. For a hybrid network of n nodes and m base stations, the results show that if m grows asymptotically slower than √n, the benefit of adding base stations on capacity is insignificant. However, if m grows faster than √n, the throughput capacity increases linearly with the number of base stations, providing an effective improvement over a pure ad hoc network. Therefore, in order to achieve nonnegligible capacity gain, the investment in the wired infrastructure should be high enough.

Integration of 802.11 and third-generation wireless data networks

Abstract: The third-generation (3G) wide area wireless networks and 802.11 local area wireless networks possess complementary characteristics. 3G networks promise to offer always-on, ubiquitous connectivity with relatively low data rates. 802.11 offers much higher data rates, comparable to wired networks, but can cover only smaller areas, suitable for hot-spot applications in hotels and airports. The performance and flexibility of wireless data services would be dramatically improved if users could seamlessly roam across the two networks. In this paper, we address the problem of integration of these two classes of networks to offer such seamless connectivity. Specifically, we describe two possible integration approaches - namely tight integration and loose integration and advocate the latter as the preferred approach. Our realization of the loose integration approach consists of two components: a new network element called IOTA gateway deployed in 802.11 networks, and a new client software. The IOTA gateway is composed of several software modules, and with cooperation from the client software offers integrated 802.11/3G wireless data services that support seamless intertechnology mobility, Quality of Service (QoS) guarantees and multiprovider roaming agreements. We describe the design and implementation of the IOTA gateway and the client software in detail and present experimental performance results that validate our architectural approach.

Method and apparatus for providing secure connectivity in mobile and other intermittent computing environments

Abstract: Method and apparatus for enabling secure connectivity using standards­based Virtual Private Network (VPN) IPSEC algorithms in a mobile and intermittently connected computing environment enhance the current standards based algorithms by allowing migratory devices to automatically (re)establish security sessions as the mobile end system roams across homogeneous or heterogeneous networks while maintaining network application session. The transitions between and among networks occur seamlessly -- shielding networked applications from interruptions in connectivity. The applications and/or users need not be aware of these transitions, although intervention is possible. The method does not require modification to existing network infrastructure and/or modification to networked applications.

Efficient mobility management for vertical handoff between WWAN and WLAN

Abstract: As we move toward next-generation all-IP wireless networks, we are facing the integration of heterogeneous networks, such as WWAN and WLAN, where vertical handoff is required. In vertical handoff between WWAN and WLAN, mobile hosts should be able to move freely across different networks while satisfying QoS requirements for a variety of applications. In order to achieve seamless handoff and maintain continuity of connection, we propose a novel mobility. management system that integrates a connection manager to detect network condition changes in a timely and accurate manner, and a virtual connectivity manager that uses an end-to-end principle to maintain a connection without additional network infrastructure support. A prototype system was built to test the effectiveness of the proposed system. Experiments show that seamless roaming between WLAN and WWAN can be achieved, and much better performance can be obtained than with the traditional scheme.

Pricing network edges for heterogeneous selfish users

Abstract: We study the negative consequences of selfish behavior in a congested network and economic means of influencing such behavior. We consider a model of selfish routing in which the latency experienced by network traffic on an edge of the network is a function of the edge congestion, and network users are assumed to selfishly route traffic on minimum-latency paths. The quality of a routing of traffic is measured by the sum of travel times (the total latency).It is well known that the outcome of selfish routing (a Nash equilibrium) does not minimize the total latency. An ancient strategy for improving the selfish solution is the principle of marginal cost pricing, which asserts that on each edge of the network, each network user on the edge should pay a tax offsetting the congestion effects caused by its presence. By pricing network edges according to this principle, the inefficiency of selfish routing can always be eradicated.This result, while fundamental, assumes a very strong homogeneity property: all network users are assumed to trade off time and money in an identical way. The guarantee also ignores both the algorithmic aspects of edge pricing and the unfortunate possibility that an efficient routing of traffic might only be achieved with exorbitant taxes. Motivated by these shortcomings, we extend this classical work on edge pricing in several different directions and prove the following results.We prove that the edges of a single-commodity network can always be priced so that an optimal routing of traffic arises as a Nash equilibrium, even for very general heterogeneous populations of network users.When there are only finitely many different types of network users and all edge latency functions are convex, we show how to compute such edge prices efficiently.We prove that an easy-to-check mathematical condition on the population of heterogeneous network users is both necessary and sufficient for the existence of edge prices that induce an optimal routing while requiring only moderate taxes.

Advanced multi-network client device for wideband multimedia access to private and public wireless networks

Abstract: A wireless device (e.g., a wireless smart phone) uses Global Positioning System (GPS) data, or other position-indicating data, to accurately determine its location in relation to multi-layered wireless networks that the device may see concurrently. If location information is available, the device employs a user-defined priority table to select the order of user-contracted networks available at that location in which the device will register. If location information is unavailable, the device employs a technology priority table to select Common Air Interface (CAI) options for the invention device radio parameters (e.g., GSM, cdma2000, IS-136, IEEE 802.11x, etc.) to search for an available network to access. Information is gathered and stored in databases within the invention device allowing it to be registered in multiple wireless networks. The inventive device provides unique access codes to each wireless network with which a user has contracted, without the intervention of any “anchor” (home) network. The invention facilitates equivalent “home”, or personalized, service in any network by using these features for automatic technology adaptation. This allows the invention device to receive service as if it is in a “home” network no matter what network it is traveling through. The invention provides a ubiquitous experience allowing the user to traverse multiple wireless networks with seamless access to multiple systems and services provided by those networks. It also provides a platform to facilitate the customization of wireless services for business customers.

Systems and methods for seamless roaming between wireless networks

Abstract: A method for the seamless switching of a wireless device between wireless wide area networks (WWANs) and wireless local area networks (WLANs) includes automatically detecting the available WWANs and WLANs, selecting one of the available networks for use by the wireless device, and connecting the wireless device to the selected network. The method also includes maintaining the network connection by monitoring the connection and, upon determining that the connection has been lost, selecting a another available network for use and connecting the wireless device the other network. Additionally, the method communicates information about the availability networks and connection status to a user of the wireless device, which allows the user to manually switch the wireless device connection from the automatically selected available network to another available network. Further, a wireless device implements the above described method.

A short survey of wireless sensor networks

Abstract: Note: The material in this technical report has also appeared as part of the report of the Working Group 2 " Ad hoc networks " of the " Arbeitsgruppe Mobikom " of the DLR/BMBF.

Software Defined Radio: Architectures, Systems and Functions

Abstract: Preface.Abbreviations.Contributors' Biographies.Introduction.PART I: RECONFIGURABILITY IN HETEROGENEOUS NETWORKS.Reconfigurable Systems in a Heterogeneous Environment (M. Dillinger & S. Buljore).PART II: REQUIREMENTS FOR RECONFIGURABLE TERMINALS.User Requirements for SDR Terminals (R. Navarro-Prieto & G. Conaty).The Need for Network Reconfigurability Management (N. Alonistioti & N. Houssos).Adaptive Protocols (S. Panagiotakis & V. Gazis).PART III: NETWORKS SUPPORTING RECONFIGURABLE TERMINALS.Network Architectures and Functions (N. Olaziregio, et al.).Self-Learning and Adaptive Systems: The CODA Approach (T. Karran, et al.).Open APIs for Flexible Service Provision and Reconfiguration Management (N. Alonistioti, et al.).Framework for Charging and Billing for Reconfigurable Services (N. Alonistioti & M. Koutsopoulou).PART IV: PROFILE AND RADIO RESOURCE MANAGEMENT.Communication Profiles (E. Mohyeldin, et al.).Radio Re source Management in Heterogeneous Networks (J. Luo, et al.).An Efficient Scheme of JRRM and Spectrum-Sharing Methods (D. Bourse, et al.).Mode Identification and Monitoring of Available Air Interfaces (G. Vardoulias & J. Faroughi-Esfahani).PART V: SOFTWARE AND HARDWARE RECONFIGURATION.Reconfiguration of the Network Elements (G. Rabai & S. Imre).Management, Control and Data Interfaces (K. Moessner & S. Gultchev).Reconfiguration Principles for Adaptive Baseband (D. Lund & M. Mehta).Index.

Location blocking service for wireless networks

Abstract: The invention disclosed is a location blocking service for use in a wireless network that tracks the location and identity of network users, such as networks complying with enhanced 911 standards. The service provides a network user with the ability to prevent the location of her wireless handheld device from being disclosed to parties other than the wireless network provider and PSAPs (Public Safety Answering Points). The network user blocks the forwarding of location information by signaling to the wireless handheld device when the location information originates from the wireless handheld device, or by signaling to the network when the location information originates from the wireless handheld device or the network. Primary components of the present invention include at least one user interface and at least one location block processor provisioned in the wireless handheld device and/or the wireless network. The user interface prompts the user of the handheld device to enter the commands that the send the signals to the device or network.

Efficient authentication and key distribution in wireless IP networks

Abstract: Emerging broadband access technologies such as 802.11 are enabling the introduction of wireless IP services to an increasing number of users. Market forecasts suggest that a new class of network providers, commonly referred to as wireless Internet service providers, will deploy public wireless networks based on these new technologies. In order to offer uninterrupted IP service combined with ubiquitous seamless mobility, these multiprovider networks need to be integrated with each other, as well as with wide-area wireless technologies such as third-generation cdma2000 and UMTS. Therefore, efficient authentication and dynamic key exchange protocols that support heterogeneous domains as well as networks with roaming agreements across trust boundaries are key to the success of wide-area wireless IP infrastructures. In this article we first describe a simple network model that accounts fro heterogeneity in network service providers, and put forward the requirements any authentication and key exchange protocol that operates in such a model should satisfy, in terms of network efficiency, security, and fraud prevention. We then introduce a new authentication and key exchange protocol, wireless shared key exchange (W-SKE). We characterize properties and limitations of the W-SKE against the requirements discussed earlier. Finally, we contrast W-SKE against other well-known and emerging approaches.

Propagation and immunization of infection on general networks with both homogeneous and heterogeneous components

Abstract: We consider the entire spectrum of architectures of general networks, ranging from being heterogeneous (scale-free) to homogeneous (random), and investigate the infection dynamics by using a three-state epidemiological model that does not involve the mechanism of self-recovery. This model is relevant to realistic situations such as the propagation of a flu virus or information over a social network. Our heuristic analysis and computations indicate that (1) regardless of the network architecture, there exists a substantial fraction of nodes that can never be infected and (2) heterogeneous networks are relatively more robust against spreads of infection as compared with homogeneous networks. We have also considered the problem of immunization for preventing wide spread of infection, with the result that targeted immunization is effective for heterogeneous networks.

System and method for providing an interactive screen on a wireless device interacting with a server

Abstract: A system and method for displaying an interactive screen, such as an end-user license agreement or verification form, on the graphic display of a wireless device when the wireless device connects to a network server on a wireless network and attempts to access or download software applications and data. The user of the wireless device must then affirmatively interact with the interactive screen in order to access or download a software application or data from the network server. The interactive screen can be transmitted from the network server where the wireless device seeks to access or download an application or data, or can be transmitted from a separate server to the wireless device. The records of the wireless device-server interactions can be stored on a network server or other data stores on the wireless network.

Portable wireless gateway

Abstract: A portable wireless network gateway aggregates bandwidth demand of different devices operating under different communications protocols Network connectivity is provided by encapsulating data from the different devices to make the data appear to be data native to a single network For example, the single network is a cellular wireless network The different communications protocols include but are not limited to IEEE 80211, IEEE 8023, USB, cellular wireless protocols, Bluetooth, RS-232, and IEEE 111R

Mobility support in wireless Internet

Abstract: The tremendous advancement and popularity of wireless access technologies necessitates the convergence of multimedia (audio, video, and text) services on a unified global (seamless) network infrastructure. Circuit-switched proprietary telecommunication networks are evolving toward more cost-effective and uniform packet-switched networks such as those based on IP. However, one of the key challenges for the deployment of such wireless Internet infrastructure is to efficiently manage user mobility. To provide seamless services to mobile users, several protocols have been proposed over the years targeting different layers in the network protocol stack. In this article we present a cross-layer perspective on the mobility protocols by identifying the key features of their design principles and performance issues. An analysis of the signaling overhead and handoff delay for some representative protocols in each layer is also presented. Our conclusion is that although the application layer protocol is worse than the protocols operating in the lower layers, in terms of handoff delay and signaling overhead, it is better suited as a potential mobility solution for the next-generation heterogeneous networks, if we consider such factors as protocol stack modification, infrastructure change, and inherent operational complexity.

A multiqueue service room MAC protocol for wireless networks with multipacket reception

Abstract: An adaptive medium-access control (MAC) protocol for heterogeneous networks with finite population is proposed. Referred to as the multiqueue service room (MQSR) protocol, this scheme is capable of handling users with different quality-of-service (QoS) constraints. By exploiting the multipacket reception (MPR) capability, the MQSR protocol adaptively grants access to the MPR channel to a number of users such that the expected number of successfully received packets is maximized in each slot. The optimal access protocol avoids unnecessary empty slots for light traffic and excessive collisions for heavy traffic. It has superior throughput and delay performance as compared to, for example, the slotted ALOHA with the optimal retransmission probability. This protocol can be applied to random-access networks with multimedia traffic.

Method and system wherein handover information is broadcast in wireless local area networks

Abstract: A method and system wherein handover information is broadcast in a wireless local area network (1-6). Handover information is broadcast in a beacon frame thereby allowing WTRUs operating in a wireless area network to handover to available alternative systems as desired (11). WTRUs may read the beacon frame and obtain appropriate information for handing over to alternative systems having coverage areas that overlap that of the wireless local area network (2-6). The alternative systems may be any type of wireless system and the wireless local area network may be any type of wireless area network.

A survey on network protocols for wireless sensor networks

Abstract: Recent advances in MEMS (micro-electromechanical systems), processor, radio, and memory technologies have dramatically enabled development of wireless sensor networks A sensor network is a large network of small sensor nodes, capable of sensing, communication, and computation It can be deployed to sense some physical phenomenon for a wide variety of applications During recent years, research in wireless sensor networks has become more and more active Network protocols developed for sensor networks are of great importance to meet specific design goals of sensor networks We present a survey of recent work addressing network protocols, including routing and information dissemination algorithms, for wireless sensor networks We evaluate them in terms of design goals, assumptions, operation models, energy models, and performance metrics

Traffic engineering in multigranularity heterogeneous optical WDM mesh networks through dynamic traffic grooming

Abstract: In this article we investigate the problem of efficiently provisioning connections of different bandwidth granularities in a heterogeneous WDM mesh network through dynamic traffic grooming schemes under traffic engineering principles Due to the huge amount of traffic a WDM backbone network can support and the large geographic area it can cover, constructing and upgrading such an optical WDM network can be costly Hence, it is extremely important for network operators to apply traffic engineering strategies to cost-effectively support different bandwidth granularity services using only the appropriate amount of network resources This requires an optical WDM network to have multigranularity switching capability, and such a network tends to be a multivendor heterogeneous network However, WDM network heterogeneity increases the difficulty and challenge of efficient traffic provisioning In this article we present different TE issues that need to be carefully considered in such an optical WDM network, and propose possible solutions and extensions for the generalized multiprotocol label switching optical network control plane We extend an existing generic graph model to perform efficient traffic grooming and achieve different TE objectives through simple shortest path computation algorithms We show that our approach is very practical and very suitable for traffic engineering in a heterogeneous multigranularity optical WDM mesh network

EMPOWER: a network emulator for wireline and wireless networks

Abstract: The increasing need of protocol development environments and network performance evaluation tools gives rise to the research of flexible, scalable, and accurate network emulators. The desired network emulator should be able to facilitate the emulation of either wireline or wireless networks. In the case when network topology is critical to the underlying network protocol, the emulator should provide specific mechanisms to emulate network topology. In this paper, we present a distributed network emulation system EMPOWER, which not only can fulfill those requirements, but also can generate user-defined network conditions and traffic dynamics at packet level. EMPOWER is highly scalable in that each emulator node could be configured to emulate multiple network nodes. Some significant research issues such as topology mapping scheme and scalability of the emulator are discussed and addressed. Preliminary emulation results show that EMPOWER is capable of assisting the study of both wireless and wireline network protocols and applications.

Validating and Securing Spontaneous Associations between Wireless Devices

Abstract: One of the sought-after characteristics of mobile and ubiquitous computing environments is for devices to become spontaneously associated and interoperate over wireless networks. However, unlike the cable that connects two devices in a wired association, a wireless network does not provide a physical indication of which device is on the other end of the association. Further, the messages sent over a wireless network are readily accessible to other devices on the same network. Hence, a spontaneous wireless association is subject to various spoofing and replay attacks. We introduce protocols to thwart these attacks by physically validating the two devices in a wireless association and, in so doing, exchanging a shared session key between them for subsequent secure communication.

System and method for content delivery using alternate data paths in a wireless network

Abstract: A system and method for allowing a mobile telephone or mobile terminal (210) to interact with its wireless telephone/data service (230), including conventional 2G and 3G systems (hereinafter the 'wireless network')(240), and also to interact with local-area services such as WLAN (270), BlueTooth (260), and personal area networks, and to communicate with and use systems and peripherals (280) available on those networks. Since the mobile terminal is a trusted device on the wireless network, it also then acts as a gateway to allow other local-area services and devices to connect and communicate with the wireless network. When a user of the mobile terminal or a local-area device requests a data service that can be delivered over either the wireless network or the local-area network, the more-efficient data path is determined and the user can select the preferred data path.

Dynamically managing and reconfiguring wireless mesh networks

Abstract: A wireless network with multiple subscriber systems in a lobe pool may operate by determining a state of the wireless network, identifying a new condition, the new condition including a new demand condition or a new network health condition, determining whether the new condition has a threshold impact on operations of the wireless network or component subscriber systems of the wireless network, and if the threshold impact exists, reconfiguring the wireless network to accommodate the new condition.

Indoor location estimation using multiple wireless technologies

Abstract: Future mobile devices will increasingly have multiple sources of location information associated with them, such as GPS, cellular cell-sector ID, Bluetooth or 802.11 wireless LAN. In fact, cellular phones with GPS receivers and 802.11 wireless LAN are already becoming available. However, not all location technologies will operate everywhere (e.g. GPS typically will not work indoors whereas 802.11 coverage may be available) and they typically have different accuracies and range. This paper presents an experimental study of the feasibility of using multiple wireless technologies simultaneously for location estimation. We have collected signal strength information from both IEEE 802.11 and Bluetooth wireless network technologies, developed and applied algorithms for determining location using data for each wireless technology, and then used a simple algorithm for fusing the location estimates from both technologies to try to enhance the accuracy of the location estimates.

System and method for integrating local-area and wide-area wireless networks

Abstract: A system and method for allowing a mobile telephone or mobile terminal (210) to interact with its wireless telephone/data service (230), including conventional 2G and 3G systems (hereinafter the 'wireless network') (240), and also to interact with local-area services such as WLAN (270), BlueTooth (260), and personal area networks, and to communicate with and use systems and peripherals (280) available on those networks. Since the mobile terminal is a trusted device on the wireless network, it also then acts as a gateway to allow other local-area services and devices to connect and communicate with the wireless network.

Efficient PDA synchronization

Abstract: Modern personal digital assistant (PDA) architectures often utilize a wholesale data transfer protocol known as "slow sync" for synchronizing PDAs with personal computers (PCs). This approach is markedly inefficient with respect to bandwidth usage, latency, and energy consumption since the PDA and PC typically share many common records. We propose, analyze, and implement a novel PDA synchronization scheme (CPIsync) predicated upon previous information-theoretic research. The salient property of this scheme is that its communication complexity depends on the number of differences between the PDA and PC, and is essentially independent of the overall number of records. Moreover, our implementation shows that the computational complexity and energy consumption of CPIsync is practical and that the-overall latency is typically much smaller than that of slow sync or alternative synchronization approaches based on Bloom (1970) filters. Thus, CPIsync has potential for significantly improving synchronization protocols for PDAs and, more generally, for heterogeneous networks of many machines.

Wireless network clustering communication system, wireless communication network, and access port for same

Abstract: A wireless communication network includes a plurality of network coordinators communicating over a first wireless area network, such as an IEEE 802.11 wireless local area network. A plurality of network devices communicate over a second wireless personal area network, such as an IEEE 802.15.4 wireless network. One or more of the network coordinators may be hybrid access points for the corresponding network devices to access the first wireless area network. The hybrid access points include a first wireless transceiver communicating over the first wireless area network, a second wireless transceiver communicating over the corresponding second wireless network, and a processor coordinating communications between the first wireless area network and the corresponding second wireless network.

Power-efficient data dissemination in wireless sensor networks

Abstract: This paper presents a new event-based communication model for wireless multi-hop networks of energy-constrained devices such as sensor networks. The network is arranged as an event dissemination tree, with nodes subscribing to the event types they are interested in. An event scheduler dynamically allocates and multiplexes upstream and downstream time slots for each event type. Power consumption among wireless nodes is reduced by allowing each node to power down its radio during the portions of the schedule that do not match its particular event subscription. The event dissemination schedule can be determined in both a centralized and distributed fashion, and is highly dynamic to suit the changing rates at which events are generated and distributed through the network. The paper also presents preliminary performance results that demonstrate the power savings achieved by the proposed protocols.

System and method for delivering data services in integrated wireless networks

Abstract: A system and method for allowing a mobile telephone or mobile terminal (210) to interact with its wireless telephone/data service (230), including conventional 2G and 3G systems (hereinafter the 'wireless network') (240), and also to interact with local-area services such as WLAN (270), BlueTooth (260), and personal area networks, and to communicate with and use systems and peripherals (280) available on those networks. Since the mobile terminal is a trusted device on the wireless network, it also then acts as a gateway to allow other local-area services and devices to connect and communicate with the wireless network. The user can select, and the wireless network can determine, data services that correspond to local-area devices. Once selected, the data service is delivered to the local-area device via the wireless network and the mobile terminal.