Showing papers on "Wireless WAN published in 1998"

Vertical handoffs in wireless overlay networks

Abstract: No single wireless network technology simultaneously provides a low latency, high bandwidth, wide area data service to a large number of mobile users. Wireless Overlay Networks – a hierarchical structure of room-size, building-size, and wide area data networks – solve the problem of providing network connectivity to a large number of mobile users in an efficient and scalable way. The specific topology of cells and the wide variety of network technologies that comprise wireless overlay networks present new problems that have not been encountered in previous cellular handoff systems. We have implemented a vertical handoff system that allows users to roam between cells in wireless overlay networks. Our goal is to provide a user with the best possible connectivity for as long as possible with a minimum of disruption during handoff. Results of our initial implementation show that the handoff latency is bounded by the discovery time, the amount of time before the mobile host discovers that it has moved into or out of a new wireless overlay. This discovery time is measured in seconds: large enough to disrupt reliable transport protocols such as TCP and introduce significant disruptions in continuous multimedia transmission. To efficiently support applications that cannot tolerate these disruptions, we present enhancements to the basic scheme that significantly reduce the discovery time without assuming any knowledge about specific channel characteristics. For handoffs between room-size and building-size overlays, these enhancements lead to a best-case handoff latency of approximately 170 ms with a 1.5% overhead in terms of network resources. For handoffs between building-size and wide-area data networks, the best-case handoff latency is approximately 800 ms with a similarly low overhead.

BLUETOOTH—The universal radio interface for ad hoc, wireless connectivity

Abstract: that is small enough to fit inside any electronic device or machine, that provides local connectivity, and that creates a (worldwide) micro-scale web. What applications might you use it in? In 1994, Ericsson Mobile Communications AB in Lund, Sweden, initiated a study to investigate the feasibility of a low-power, low-cost radio interface between mobile phones and their accessories. The intention was to eliminate cables between phones and PC cards, wireless headsets, and so forth. The study was part of a larger project that investigated multi-communicators connected to the cellular network via cellular telephones. The last link in the connection between a communicator and the cellular network was a short-range radio link to the phone—thus, the link was called the multicommunicator link or MC link. As the MC link project progressed, it became clear that there was no limit to the kinds of application that could use a short-range radio link. Cheap, short-range radios would make wireless communication between portable devices economically feasible. Current portable devices use infrared links (IrDA) to communicate with each other. Although infrared transceivers are inexpensive, they • have limited range (typically one to two meters); • are sensitive to direction and require direct line-of-sight; • can in principle only be used between two devices. By contrast, radios have much greater range, can propagate around objects and through various materials, and connect to many devices simultaneously. What is more, radio interfaces do not require user interaction. In the beginning of 1997, when designers had already begun work on an MC link

Toward power-sensitive network architectures in wireless communications: concepts, issues, and design aspects

Abstract: Transmitter power control can be used to concurrently achieve several key objectives in wireless networking, including minimizing power consumption and prolonging the battery life of mobile nodes, mitigating interference and increasing the network capacity, and maintaining the required link QoS by adapting to node movements, fluctuating interference, channel impairments, and so on. Moreover, power control can be used as a vehicle for implementing on-line several basic network operations, including admission control, channel selection and switching, and handoff control. We consider issues associated with the design of power-sensitive wireless network architectures, which utilize power efficiently in establishing user communication at required QoS levels. Our focus is mainly on the network layer and less on the physical one. Besides reviewing some of the developments in power control, we also formulate some general associated concepts which have wide applicability to wireless network design. A synthesis of these concepts into a framework for power-sensitive network architectures is done, based on some key justifiable points. Various important relevant issues are highlighted and discussed, as well as several directions for further research in this area. Overall, a first step is taken toward the design of power-sensitive network architectures for next-generation wireless networks.

Critical power for asymptotic connectivity

Abstract: In wireless data networks the range of each transmitter, and thus its power level, needs to be high enough to reach the intended receivers, while being low enough to avoid generating interference for other receivers on the same channel. If the nodes in the network are assumed to cooperate, perhaps in a distributed and decentralized fashion, in routing each others' packets, as is the case in ad hoc wireless networks, then each node should transmit with just enough power to guarantee connectivity of the overall network. Towards this end, we determine the critical power at which a node in the network needs to transmit in order to ensure that the network is connected with probability one as the number of nodes in the network goes to infinity. Our main result is this: if n nodes are located randomly, uniformly i.i.d., in a disc of unit area in /spl Rfr//sup 2/ and each node transmits at a power level so as to cover an area of /spl pi/r/sup 2/=(log n + c(n))/n, then the resulting network is asymptotically connected with probability one if and only if c(n)/spl rarr/+/spl infin/.

Method and system for seamless roaming between wireless communication networks with a mobile terminal

Abstract: A mobile computer system capable of seamless roaming between wireless communication networks includes data processing resources for executing software, a plurality of wireless interfaces that supports simultaneous wireless connections with first and second wireless communication networks, and a network access arbitrator that routes data communicated between the software executed by the data processing resources and the first and second wireless communication networks. To permit seamless roaming, the network access arbitrator routes the data to the first wireless communication network via a first wireless interface and then seamlessly reroutes the data to a second wireless communication network via a second wireless interface. According to one embodiment, the network access arbitrator reroutes the data in response to the data bandwidths of the connections with the first and second wireless communication networks.

A method and apparatus for an automatic multi-rate wireless/wired computer network

Abstract: A method and apparatus for implementing a wireless/wired computer network in an indoor environment with inherent reliability is disclosed. A master network box connected to an AC power network and a master computer generates an RF field around the computer, the home, and AC power network. The integration and implementation of additional devices to the established network is made through additional appliance boxes. Once introduced into the generated RF field, or connected to the AC power network, the additional device is automatically and seamlessly registered and configured into the network without requiring any user intervention. The network is capable of multiple modulation schemes for providing robust wired or wireless communication for various devices which have different power and data rates. The programming of the master computer enables the automated registration of additional devices, and can provide superior control over the devices connected to the network, either via the AC power network, or via RF wireless transmission through the multiple modulation schemes.

Adapting packet fair queueing algorithms to wireless networks

Abstract: Parames~varan Ramana.tllan Pratbinla t\graIval Dept. of Elect. & Comp. Engr. I[)ter]~et. ArcIl. Research Lab University of Wisconsin Bellcore, hIorristotvn Nladison, WI 53706 Ne\v .Jersey 07960. parmesll!@ece.\visc.edu pagra~val(~bellcore. com Bit errors are fairly common during transmission in a wireless network. As a result, a straight-forwarcl application of existing packet fair queueing (PFQ) algorithms from wireIine to wireless networks results in an ine~cient use of ~he Kmited wireless bandwidth. In this paper, we propose a simple approach for adapting the existing PFQ algorithms for the wire]ine networks to provide the same kind of long-term fairness guarantees while making efficient use of the wireless bandwidth. In the proposed approach, long-term fairness guarantees are provided by supplementing the bandwidth given to sessions which have not received satisfactory service in the short -term due to poor quahty of their wireless channel. To efficiently keep track of the amount of supplemental bandwidth for each session, the paper introduces the concept of a long-term fairness server. This concept. also allows one to easily integrate the proposed approach with any of the existing PFQ algorithms.

Optimum routing system

Abstract: A wireless data network includes a wireless packet switched data network for end users that divides mobility management into local, micro, macro and global connection handover categories and minimizes handoff updates according to the handover category. The network integrates MAC handoff messages with network handoff messages. The network separately directs registration functions to a registration server and direct routing functions to inter-working function units. The network provides an intermediate XTunnel channel between a wireless hub (also called access hub AH) and an inter-working function unit (IWF unit) in a foreign network, and it provides an IXTunnel channel between an inter-working function unit in a foreign network and an inter-working function unit in a home network. The network enhances the layer two tunneling protocol (L2TP) to support a mobile end system, and it performs network layer registration before the start of a PPP communication session.

Network access methods, including direct wireless to internet access

Abstract: A method is provided for connecting a source of digital data to a computer network. The source of digital data transmits data over a wireless transmission medium to a wireless service carrier, the wireless service carrier multiplexing the digital data onto a high speed digital telephone line. The method comprises the steps of receiving the digital data at a communications chassis such as a network access server, extracting, from the digital data, network access authentication data comprising at least one of the following: (a) a telephone number called by the source of digital data, or (b) a telephone number associated with the source of digital data; transmitting the authentication data over a local area or wide area computer network connected to a network authentication server for the computer network; determining, in the network authentication server, from the transmitted authentication data whether the remote user is permitted to access the computer network; and the authentication server responsively notifying the network access server the results of the step of determining; and authorizing the source of data to access the computer network if the step of determining results in a positive response.

Network device for supporting construction of virtual local area networks on arbitrary local and wide area computer networks

Abstract: A network device that translates addresses of machines on physically separate networks and filters packets at the link, network and transport layers implements a virtual LAN over interconnected computer networks transparent to the computer networks. Using authentication and encryption, a secure connection between these network devices over a public wide area network implements a virtual private network and enables the definition of virtual LANs over the virtual private network. The network device has three tables for network address translation, routing, and filtering. A controller processes each incoming packet by translating network addresses to determine the destination of the packet, routing the packet to the determined location and filtering the packet according to filters defined for traffic between the source destination of the packet. If the packet is to be directed to a wide area network, encryption and authentication procedures can be provided to ensure secure transmission of the packet.

Connection establishment method, communication method, state change transmission method, state changing method, wireless apparatus, wireless device, and computer

Abstract: A wireless hub, connected to the USB bus of a computer, and a wireless port, connected to a USB interface of a peripheral device, are provided, and wireless communication is performed between the two. The wireless hub performs communication with the computer by converting a USB packet routed to a device into a wireless signal, and a wireless signal received from a device into a USB packet. The wireless port attached to each device also converts a wireless signal into a USB packet and vice versa. While it is normal for a plurality of wireless ports to be connected to a single wireless hub, an arrangement of one wireless hub and a corresponding single wireless port is also possible. A wireless hub and a wireless port each have a device identifier assigned to them, and in the USB-wireless conversion, a non-specific destination identified by a USB address and bus topology is converted into a device identifier. Inter-host communication is enabled by using the device identifier.

A network-conscious approach to end-to-end video delivery over wide area networks using proxy servers

Abstract: In this paper we present a novel network-conscious approach to the problem of end-to-end video delivery over wide-area networks using proxy servers situated between local-area networks (LANs) and a backbone wide-area network (WAN). We develop a novel and effective video delivery technique called video staging via intelligent utilization of the disk bandwidth and storage space available at proxy servers. We also design several video staging methods and evaluate their effectiveness in reducing the backbone WAN bandwidth requirement. Our results demonstrate that the proposed proxy-server-based, network-conscious approach provides an effective and scalable solution to the problem of the end-to-end video delivery over wide-area networks.

Mobility management system

Abstract: A wireless data network includes a wireless packet switched data network for end users that divides mobility management into local, micro, macro and global connection handover categories and minimizes handoff updates according to the handover category. The network integrates MAC handoff messages with network handoff messages. The network separately directs registration functions to a registration server and direct routing functions to inter-working function units. The network provides an intermediate XTunnel channel between a wireless hub (also called access hub AH) and an inter-working function unit (IWF unit) in a foreign network, and it provides an IXTunnel channel between an inter-working function unit in a foreign network and an inter-working function unit in a home network. The network enhances the layer two tunneling protocol (L2TP) to support a mobile end system, and it performs network layer registration before the start of a PPP communication session.

Apparatus and method for peer-to-peer link monitoring of a wireless network with centralized control

Abstract: Centrally controlled wireless networks require reliable communications between the central controller and each of the stations within the wireless networks. The structure of a wireless network is often dynamic, or ad-hoc, as stations enter and exit the network, or are physically relocated. The selection of the central controller for the network may also be dynamic, either because the current central controller desires to exit the network, or because the communication between the current central controller and one or more of the stations is poor. This invention discloses a method and apparatus for assessing the quality of the communication paths among all stations in the network. This assessment is useful as a continual monitor of the quality of the network, and can be utilized to select an alternative central control station based upon the quality of communication paths to and from this station. Additionally, the quality assessment can be utilized to establish relay communication paths, as required.

A wireless fair service algorithm for packet cellular networks

Abstract: Wireless Fair Service Algorithm For Packet Cellular Networks Sonwu Lu Thyagarajan Nandagopal Vaduvur Bharghavan Coordinated Science Laboratory University of Illinois email: {sIu, thyagu, bharghav}~timely. crhc .uiuc. edu b order to support diverse communication-intensive redtirne and non red-time data flows over a scarce, varying and shared wireless channel with location-dependent and bursty errors, we defie a service model that has the following charxteristi~ short-tern fairness among flows which perceive a clean channel, worst-case delay bounds for packets, short-term throughput bounds for flows with clean channels and Iong-tem throughput bounds for dl flows with bounded channel error, optimal schedulable region, and support for both delay sensitive and error sensitive data flows. We present a wireless fair service algorithm, and show that it achieves the requirements of the service model through both analysis and simulation. The key aspects of the dg~ rithm are the following (a) an enhanced fair queueing based service scheme that supports decoupling of delay and bandwidth, (b) graceful service compensation for lagging flows and graceful service degradation for leading flows, (c) support for red-time delay sensitive flows as well as non realtime error sensitive flows, and (d) implementation of the wireless fair service rdgorithm within the fiarnework of the simple and robust CSMA/CA wireless medium access pro tocol.

Apparatus and method for management of resources in cellular networks

Abstract: Wireless networks require efficient mobility management to cope with frequent mobile handoff and rerouting of connections. The invention treats this problem by developing a hierarchical prediction engine that employs approximate pattern matching and Kalman filtering techniques to yield an accurate prediction of both the immediate next cell to be entered by the mobile and the overall or global route of the mobile unit in the wireless cellular network. The prediction of the mobile's future movement is used by the network to reserve resources, relieve congestion, reduce latency, and optimize the establishment of routes in the wireless cellular network.

Wireless atm network with high quality of service scheduling

Abstract: Methods and systems for a wireless ATM network with high quality of service scheduling are provided. In one embodiment, a wireless ATM network with per-VC scheduling, a virtual framer for periodical, request-less scheduling, and a virtual shaper for request-based scheduling are provided.

Network hub for interconnecting a wireless office environment with a public cellular telephone network

Abstract: A network hub (38) for interconnecting a first network (40) transceiving signals according to a SS7 protocol with a second network (12) transceiving signals according to a TCP/IP protocol is disclosed. The network hub (38) includes means for interconnecting the hub (38) with each of the first and second networks. A processing means within the hub converts received signals between being carried by the SS7 and TCP/IP protocols. The conversions are assisted by a translation table (70) including active mobile identification numbers and IP addresses within the second network and a second table (72) listing all signal point codes for nodes within the first network.

Home area network system and method

Abstract: A home area network system and method uses existing plain old telephone system (POTS) wiring to network computers in a home without disrupting conventional telephone services. The home area network assigns a network address to each computer coupled to the network and communicates using a broadband communication method occupying the portion of the spectrum above the baseband portion used by ordinary telephone service. The home area network employs quadrature phase shift keying (QPSK) modulation on unshielded twisted pair (UTP) wiring arranged in an arbitrary topology. The home area network additionally employs adaptive equalization for each computer pair coupling as well as adaptive error correction.

Method and wireless terminal for monitoring communications and providing network with terminal operation information

Abstract: A wireless terminal monitors its communications wiht a wireless network in order to provide the network with performance information The terminal monitors its own operations and messages, or expected messages from the network, and stores information as to the success of failure of these various events Performance information, for example, bit error rate and receive signal strength is also stored The terminal is also capable of performing transmission path quality tests, for example, loop backs The terminal can transmit information to a network at regular time periods or as a response to a request from the newtwork

WebExpress: a client/intercept based system for optimizing Web browsing in a wireless environment

Abstract: This paper describes an application model and software technology that makes it possible to run World Wide Web applications in wide area wireless networks. Web technology in conjunction with today's mobile devices (e.g., laptops, notebooks, personal digital assistants) and the emerging wireless technologies (e.g., digital cellular, packet radio, CDPD) offer the potential for unprecedented access to data and applications by mobile workers. Yet, the limited bandwidth, high latency, high cost, and poor reliability of today's wireless wide-area networks greatly inhibits (to the point of infeasibility) supporting such applications over wireless networks. This paper presents the Client/Intercept computational model that makes it possible to run such distributed applications efficiently in wide area wireless networks. Furthermore, it presents WebExpress, a client/intercept based system for optimizing Web browsing, that reduces data volume and latency of wireless communications by intercepting the HTTP data stream and performing various optimizations including: file caching, forms differencing, protocol reduction, and the elimination of redundant HTTP header transmission. This paper describes these optimizations and presents some experimental results.

Mobile tele-computer network

Abstract: A telecomputer network is described. The network comprises a satellite communication system, at least one mobile vehicle, and a wireless local area network (LAN). In one embodiment, the satellite communication system transfers information using ethernet packet switching. In one embodiment, the wireless LAN transfers information using the TCP/IP protocol. The mobile vehicle or portable field unit is configured to transfer information as a single nomadic transmission/reception point between the satellite communication system and the wireless LAN.

Receiving wireless information on a mobile device with reduced power consumption

Abstract: A system and method for receiving wireless information on a portable computing device includes powering a wireless receiver only from a battery of the portable computing device. Receiving wireless information and storing the wireless information in memory of the wireless receiver. The wireless receiver wakes up a processor of the portable computing device when the wireless information fills a threshold of the memory available in the wireless receiver. The wireless information is then transferred from the memory of the wireless receiver to the memory of the portable computing device.

Method for automatically establishing a wireless link between a wireless modem and a communication device

Abstract: A first wireless link between a communication device and a wireless modem is automatically established, so that electronic messages can be easily and automatically transferred between the communication device and a data network via the first wireless link and a second link between the wireless modem and the data network. Each of the communication device and the wireless modem can automatically determine whether an electronic message is to be transferred. When one of the communication device and the wireless modem determines that an electronic message is to be transferred, the determining one of the communication device and the wireless modem sends a page signal to the other one of the communication device and the wireless modem. When the other one of the communication device and the wireless modem receives the page signal and responds, the first wireless link is established. The electronic message is then transferred between the communication device and the data network via the first wireless link and the second link. The communication device can be a portable computer such as a laptop computer, and the wireless modem can reside in a cellular or personal communication system (PCS) phone or the like.

Method for an admission control function for a wireless data network

Abstract: A method for allowing new traffic on a wireless data network. A service request is received from a mobile station (100). An effective bandwidth of the service request is estimated (110) using a recursive estimator (400). If there is enough surplus capacity on the wireless data network to accommodate the service request, the service request is granted. In response, a discrete adjustment, based on the effective bandwidth, is applied (160) to the recursive estimator (400).

Wireless Geolocation Systems and Services

Abstract: ireless communications systems, mobile cellular and PCS alike, now face the responsibility of locating emergency callers, as specified in the recent FCC ruling, and return the location information to public safety answering points (PSAPs). While the FCC ruling is the major driver for wireless providers to offer location capability, location services other than 911 emergency calls are emerging as potential value-added services and network management aids. Examples are prioritized differently by different network operators; nevertheless, they range from zone-based billing to mobile yellow pages, from roadside assistance to fleet management. Geolocation technology is a broad topic that has been established and progressed in its own right. Radar technology, the Global Positioning System (GPS), and other examples are in place. This issue is dedicated to making a wireless communications system provide geolocation services without the full-blown capabilities of these existing geolocation systems. Indeed, making a wireless communication system provide location services is a nontrivial task. The mobile phone is not a device that was designed to be “locatable.” There are numerous other challenges at every layer of the wireless communication network that need to be overcome. Some solutions involve overlaying the communications system with a location system, while others suggest integrated configurations or modifications to the mobile terminals.

Contemporaneous connectivity to multiple piconets

Abstract: A first wireless unit engages in contemporaneous participation in a plurality of wireless networks. A connection is established with a second wireless unit in a first wireless network. Then, a hold time-out period is determined, and the first wireless unit enters a hold mode with respect to the first wireless network. While in hold mode, the first wireless unit establishes a connection with a third wireless unit in a second wireless network. This may include the first wireless unit paging the third wireless unit and acting as a master unit in the second wireless network. Alternatively, the first wireless unit may periodically listen for paging messages from a master unit, and respond when paged, thereby becoming a slave in the second wireless network. The first wireless unit then participates in activities in the second wireless network. Upon expiration of the hold time-out period, the first wireless unit resumes active participation in the first wireless network. This may include determining a second hold time-out period to be used in connection with the second wireless network, and entering a hold mode with respect to the second wireless network.

Wireless interface for standard modems

Abstract: A wireless communications system for enabling an information handling system to wirelessly couple to a network is disclosed A peripheral communications device for communicating information is sent to and by the information handling system via a wireless transmission medium A base station couples to the peripheral communications device via the wireless transmission medium The information handling system is enabled to communicate over a network via the network communications device A method for communicating between an information handling system and a network via a wireless transmission medium is disclosed Information to be transmitted is sent from the information handling system to a peripheral device, translated into a wireless data transmission format, transmitted via a wireless transmission medium to a remote device, converted into a network communications format, and sent to a modem connected to the network for transmission via the network

Wireless network multicasting

Abstract: Wireless networks provide mobile users with ubiquitous communicating capability and information access regardless of location Conventional ground radio networks are the "last hop" extension of a wireline network, thus supporting only single hop communications within a "cell" In this dissertation we address a novel type of wireless networks called "multihop" networks As a difference from "single hop" (ie, cellular) networks which require fixed base stations inter-connected by a wired backbone, multihop networks have no fixed based stations nor a wired backbone The main application for mobile wireless multihopping is rapid deployment and dynamic reconfiguration When the wireline network is not available, as in battlefield communications and search and rescue operations, multihop wireless networks provide the only feasible means for ground communications and information access Multihopping poses several new challenges in the design of wireless network protocols We focus on multicasting in this thesis The multicast service is critical in applications characterized by the close collaboration of teams (eg, rescue patrol, battalion, scientists, etc) with audio/video conferencing requirements and sharing of text and images Multicasting in a multihop wireless network is much more complex than in cellular wireless networks where all mobiles in a cell can be reached in a single hop In fact, one or more multicast structures (eg, trees) are maintained in the multihop network to efficiently deliver packets from sources to destinations in the multicast group Multicast solutions similar to those used in mesh wireline networks such as the Internet might be considered Yet, these solutions are not directly applicable to wireless networks because of the mobility of the users and the dynamically changing topology In this dissertation we evaluate various popular multicast protocols via simulations and propose new protocols which are well suitable for multihop networks This dissertation mainly covers five areas: (1) Cluster-Token infrastructure and cluster routing; (2) Shared tree wireless multicast routing protocols; (3) Wireless multicast routing without Rendezvous Points; (4) On-demand wireless multicast; (5) Reliable wireless multicast