Showing papers on "Key distribution in wireless sensor networks published in 1995"

Method and apparatus for connecting a wireless lan to a wired lan

Abstract: An internetworking node for providing internetworking services for mobile wireless nodes is disclosed. Each mobile wireless node is associated with at the most one internetworking node. Each mobile wireless node selects which internetworking node it will associate with. The internetworking node will then act for all wireless nodes associated to it in relaying messages between wireless nodes or between a wired LAN and the wireless nodes.

Network management and control issues in multimedia wireless networks

Abstract: Discusses some typical multimedia applications and services that might be expected to use future wireless and combined wireless/wired networks. These include, among others, multimedia teleconferencing, the electronic newspaper, and nomadic computing. The author then describes control questions to be addressed in the mixed wireless/wired environment and control problems arising in the wireless network environment itself. Included are questions such as admission control, dynamic bandwidth control, flow control, handoff control, and resource allocation, among others. >

Wireless computer network communication system and method having at least two groups of wireless terminals

Abstract: A wireless computer network communication system for use in an environment in which plural groups can perform network communication at the same time. A channel controller receives a requirement of starting network communication from a computer, controls a wireless channel sensor, and detects a received signal. The wireless channel detector detects which wireless channel is employed by one or more other networks and the channel controller determines the wireless channel to be employed by its own group and also controls the transceiver. The computer starts the network communication through a network controller. The network controller controls the transceiver for transmitting and receiving data by use of the wireless channel, and the same further controls the transmitting/receiving of the requirements and the data from the computer.

Method for dynamically allocating wireless communication resources

Abstract: In a TDM wireless communication system (100), a central controller (104) monitors the transfer of a message (108) in order to determine a system grade of service. Based on the system grade of service, the central controller dynamically allocates a lesser or greater number of wireless communication resources (105). Alternatively, a communication unit (101) can directly request additional wireless communication resources.

Trends in local wireless networks

Abstract: Pahlavan (1985) published an article entitled "Wireless office information networks". That article examined spread spectrum, standard radio and infrared (IR) technologies for intra-office wireless networking. In May of that year the FCC released the ISM (industrial, scientific, and medical) bands for spread spectrum local communications. Although ISM bands are not restricted to any specific application, wireless local area networks (LANs) were one of the most prominent applications that were envisioned by the rule makers in the FCC. Since 1985, many small start-up companies, as well as small groups in larger companies, have started to develop wireless LANs. The present paper provides a sequel to Pahlavan by providing an overview of the past and present of the wireless LAN industry, as well as a perspective of the future directions that encompass a vision for a ubiquitous local wireless computing environment that leads to a fusion of communications and computation. >

Interference analysis of nonpersistent CSMA with hidden terminals in multicell wireless data networks

Abstract: In multi-cell wireless networks such as wireless LANs under standardization (IEEE 802.11 and ETSI's HIPERLAN), we must consider interference interaction among different cells as there are a very limited number of channels for operation. We introduce a theoretical analysis to evaluate CSMA in multicell wireless networks by taking hidden terminals, interference, and cell-overlapping into account. Both nonpersistent CSMA and CSMA with a 4-way handshaking as the IEEE 802.11 draft are considered in this paper.

Wireless communication system having base units which extracts channel and setup information from nearby base units

Abstract: A wireless communication system for servicing personal communicators is connected to a a digital switch of a landline telephone network. The communication system includes a plurality of wireless communication base units, each having wireless circuitry enabling it to extract channel and setup information other from nearby wireless communication base units. Each unit measures the RSSI of channels of neighboring wireless communication base units and makes channel assignments to a base unit in response to RSSI measurements being compared to a threshold.

Wireless terminal having digital radio processing with automatic communication system selection capability

Abstract: A wireless terminal utilizing digital radio processing utilizes stored program control to allow the wireless terminal to operate in a plurality of disposed wireless communication systems. In particular, the digital radio processing with appropriate stored program control operates in a plurality of wireless communication system by selectively and controllably enabling selection of frequency, channel bandwidth, modulation type, channel coding and source coding operational components appropriate to the communication system that the wireless unit is to operate in. A function control enables the wireless terminal to actively seek out and search for availability of wireless communications system in which it may operate.

Wireless LAN to wired LAN bridge

Abstract: An internetworking node (AP) for providing internetworking services for mobile wireless nodes (A-E) is disclosed. Each mobile wireless node is registered with at the most one internetworking node. Each mobile wireless node emits a topology broadcast identifying itself and other nodes it has heard. Each internetworking node uses these topology broadcasts to construct a table tracking each mobile node within its range, whether that mobile node is registered to that internetworking node and also a list of which other nodes that mobile wireless node can hear. The internetworking node determines which of these wireless nodes it will register. The internetworking node will then act for all wireless nodes registered to it in relaying messages between wireless nodes or between a wired LAN (50) and the wireless nodes.

Advances in Distributed Sensor Integration; Application and Theory

Abstract: From the Publisher: Advances in Distributed Sensor Integration presents the development of fault tolerant algorithms for integrating scalar valued sensor readings, vector valued sensor readings, and sensors in a given DSN architecture. In addition, the authors utilize a top-down design of the algorithms, provide a pseudo-code description, and then perform a worse case analysis of algorithms.

SpectrumWare: a software-oriented approach to wireless signal processing

Abstract: The SpectrumWare project is applying a software oriented approach to wireless communication and distributed signal processing. Advances in processor and analog-to-digital conversion technology have made it possible to implement virtual radios that directly sample wide bands of the RF

PC-notebook based mobile networking: algorithms, architectures and implementation

Abstract: The integration of multimedia adaptive wireless networking capabilities in a PC-notebook platform are investigated. To support mobile networking, while providing compatibility with the wired infrastructure, new functions are required for topology creation using multihop protocols. To support mobility in a wireless environment, power control and bandwidth allocation are required in conjunction with adaptive wireless modems and rate-adaptive video codecs. A prototype implementation of a wireless node with these capabilities reveals several performance and complexity limitations with current technology. In particular the DOS operating system, the PC shared bus architecture and traditional partitioning of the network and modem functions lead to severe performance losses that are detrimental in wireless networking. For mobile wireless nodes, these limitations are unacceptable. Several ideas are presented for re-architecting the PC-notebook for wireless networking nodes that can substantially improve bandwidth efficiency while overcoming the complexity and power limitations of current technology.

Architecture for wireless ATM networks

Abstract: This paper presents design considerations for future-generation personal communication networks (PCN) that integrate wireless access with the broadband wireline asynchronous transfer mode (ATM) network. Apart from the wireless ATM network architecture, some of the other issues that we report on include the design of the wireless-to-wireline network interfaces, and the specification of a wireless protocol reference model. Two examples are given of ways to accomplish diversity and related handoffs in the wireless ATM network.

A dynamic addressing scheme for wireless media access

Abstract: The key resource in a wireless LAN is the wireless medium itself. Since the bandwidth in wireless is typically much smaller than in wire, media access control in wireless is of critical importance in the operation of a wireless LAN. This paper proposes a protocol independent dynamic addressing scheme for wireless media access protocols, and discusses related systems and performance issues. Dynamic addressing allows spatial and temporal reuse of MAC addresses, thereby reducing the address size by a factor of 8. This reduces the control overhead in a MACAW style protocol by 30% to 70%, and produces an overall performance improvement of 5% to 33%. Dynamic addressing also serves as an enabling technology for two important features in wireless media access protocols, security and real-time support. We are implementing the dynamic addressing scheme as a part of the LCMACA wireless media access protocol.

Experiences with a Wireless Network in MosquitoNet

Abstract: As the trend towards smaller, lighter and more powerful computers continues, mobility and wireless connectivity become increasingly important. The MosquitoNet project is studying issues in wireless and mobile computing, and this paper presents our performance analysis and observations of one of the emerging wireless technologies: the Metricom Microcellular Digital Network (MCDN). Metricom provides one of the best combinations of bandwidth, coverage area and cost for a wireless data network. We find that the throughput of their radio devices is comparable to a modern modem, but the latency, or round-trip delay, is much higher. The maximum throughput we measured was 30-40 Kbits/second, but the minimum latency for even the smallest IP packet is at least 60ms. We have experimented with both the datagram and Hayes modem emulation modes of Metricom’s wireless radios. We are early users of the datagram mode, and our comparisons of these modes confirm two well-known but sometimes forgotten principles. First, packet switching allows more efficient sharing of resources than does circuit switching. Second, interfaces that are satisfactory for use by human beings often show their flaws, ambiguities and omissions when used as programming interfaces for software control of devices.

Application of neural networks to the dynamic spatial distribution of nodes within an urban wireless network

Abstract: The optimal location of wireless transceivers or communicating sensor devices in an urban area and within large human-made structures is considered. The purpose of the positioning of the devices is formation of a distributed network, either in a mesh or hub-spoke topology, that achieves robust connectivity of the nodes. Real-world examples include wireless local area networks (LANs) within buildings and radio beacons in an outdoor mobile radio environment. Operating environments contain both fixed and moving interferers that correspond to both stationary and time-varying spatial distributions of path distortion of stationary and transient fading and multipath delays that impede connectivity. The positioning of the autonomous wireless devices in an area with an unknown spatial pattern of interferers would normally be a slow incremental process. The proposed objective is determination of the spatial distribution of the devices to achieve the maximum radio connectivity in a minimal number of iterative steps. Impeding the optimal distribution of wireless nodes is the corresponding distribution of environmental interferers in the area or volume of network operation. The problem of network formation is posed as an adaptive learning problem, in particular, a self-organizing map of locally competitive wireless units that recursively update their positions and individual operating configurations at each iterative step of the neural algorithm. The scheme allows the wireless units to adaptively learn the pattern distribution of interferers in their operating environment based on the level of radio interference measured at each node by an equivalent received signal strength from wireless units within the node's hearing distance. Two cases are considered. The first is an indoor human-made environment where the interference pattern is largely deterministic and stationary and the units are positioned to form a wireless LAN. The second situation applies to an outdoor urban environment, where a fixed number of units on mobile platforms operating in a random spatial distribution of interferers.

Implementing wireless networks

Abstract: From the Publisher: Perfect for network managers working for organizations interested in connecting their various locations using networks or furnishing wireless services to mobile employees, this book explores a vast array of practical solutions for setting up state-of-the-art wireless networks in offices, field operations, retail settings, factories, and warehouses. After an illuminating introduction to wireless technology, author Martin Nemzow describes the limitations and typical uses of the various wireless transmission technologies. Wireless applications covered include site-to-site connectivity, intra site mobility, ship-to-shore connectivity, wireless packet transmission, inventory operations, mesh connections, global positioning services, E-mail on the road, product coding and tagging and shipping/receiving. For each application, Nemzow explains how to modify the wired network for wireless access, and discusses the software required. Numerous examples, along with dozens of schematics and drawings, demonstrate how to install and connect the components and software. Fine-tuning instructions, diagnostic and troubleshooting information, and performance enhancement techniques for wireless networks are also included in this authoritative handbook.

Mobility in MAP networks using the DECT wireless protocols

Abstract: This paper explores the applicability of DECT wireless systems in MAP local industrial networks. Two network architectures are considered, one based on semi-permanent circuit switching, the other one using the fast connect capability of the DECT subsystem. Performances and application domains are discussed.

A tactile sensor data-processing system

Abstract: In this paper, a framework for distributed sensor data processing is presented, where sensors with local intelligence preprocess information. A supervisor gathers the information from the sensor nodes and fuses the local sensor estimates into a global estimate, using fuzzy logic-based algorithms. Since a typical system will contain a large number of sensor nodes, the local processing will probably be performed by simple 8- or 16-bit processors. Care is thus taken to make sure that the algorithms perform well on low-end hardware. The concept is then implemented on a sensor system where local sensor processors extract information from tactile matrices, and send the data to a host over a shared serial bus. Using the distributed processing approach yields increased data-acquisition rates and offloads calculations from the system controller.

Contention protocol performance in wireless personal communication systems

Abstract: We examine the throughput, delay, and stability of a resource reservation system for a wireless personal communication network. The system we consider has a network of base transmitters, which simulcast information to a collection of mobile users, and a network of base receivers tuned to the same channel. The mobile users request bandwidth by contending during specified time slots. We present models that consider the combined effects of noise, co-channel interference, and other channel characteristics in computing the probability of successful packet transmission. We obtain numerical results via simulation that can help to understand issues involved in engineering a system.

The future of wireless applications

Abstract: Summary form only given, as follows. The measure of success of any technology is its ability to support applications which are attractive to users. Wireless supports the need to communicate with people or terminals anywhere, anytime with a maximum of ease and convenience. However, the rapid proliferation of wireless technologies may make applications too difficult to use to satisfy the mass market. The paper explores some of the enhanced voice, data and multimedia applications which will be made possible by the next generation wireless technology. It also highlights the need for middleware and user network interface standards which will make wireless services as easy to use as their wired equivalents.

Measuring NFS performance in wireless networks

Abstract: Technological trends suggest that soon communication networks will consist of a high speed wired backbone with numerous wireless Local Area Networks. Mobile computing and wireless subnetworks are increasingly in demand. Mobile routing solutions provide wireless LANs with seamless connectivity to backbone wired systems. However, these solutions do not provide acceptable performance. Wireless networks have distinct transmission characteristics which present challenges to achieving eecient performance. Performance over wireless links is limited by high error rates, mobility, and low bandwidth. We have studied the performance of TCP and NFS over a wireless network. The prevalence of these protocols means that mobile hosts will frequently use them when communicating with stationary hosts. Measurements have been collected to determine the response of these protocols in the presence of various error patterns. These measurements show that NFS and TCP performance suuer extreme degradation due to these wireless link characteristics. Unexpectedly, NFS performance is not better than an TCP FTP le transfer. NFS performance over wireless links is limited by large packet sizes, long retransmission timeouts, and slow response to losses. Our goal is to understand the eeects of wireless communication on these protocols and improve performance without requiring changes to the current network Infrastructure.

A Self-Organisation Plane for Distributed Mobile Wireless Networks

Abstract: Self-organisation functions are capable of providing organisation intelligence in communication networks. Self-organising radio networks support diverse user services in a distributed and dynamic environment. These networks involve such a variety of functions that establishment of a functional guideline or framework is necessary to manage these functions systematically. Such a framework is proposed in this paper in the form of a “plane” of self-organisation functions. Various control mechanisms or protocols can be mapped onto these functions. A practical application of the self-organisation model is demonstrated and other uses of this approach are suggested.

Quality-Of-Service Guarantees For Wireless Computer Vision

Abstract: This paper describes a cost effective and scalable design for a distributed active vision system that consists of mobile cameras, a cluster of high-performance workstations interconnected by a high bandwidth network, and a wireless LAN that connects mobile cameras with the computing cluster The goal is to support a wireless vision platform that can quickly be moved within a large wireless cell-space by hand, via remote control, or autonomously The vision algorithms are redesigned to minimize the hardware needed on the mobile platform, and to make us of a distributed network of high-speed nodes accessible by the wireless host machine This work addresses three problem areas in a distributed active vision system: the design of distributed algorithms for real-time vision processing, the need for network protocol support to achieve real-time guarantees across the wireless network connection, and development of a distributed processing framework In particular, we present designs to address three aspects of the wireless network protocol problem: providing deterministic guarantees over a multiple access wireless channel, efficient recovery from lost or corrupted packets, and synchronization of video streams We use active stereo vision and dynamic focus control as examples of the kind of vision tasks that can be supported by this environment

Building the FO infrastructure for wireless communications

Abstract: The next generation of communication systems will provide consumers with a host of new and improved voice, video, and data services. Rapidly developing wireless radio systems are already contributing to the progress, giving consumers the luxury of tetherless access to telephone conversation, on-line computing, and cable-television. Indeed, wireless access to high quality information and entertainment is quickly becoming a key component of the information superhighway. In that context, optical fiber links, which have the bandwidth for providing users with the service of their choice, are an excellent connecting infrastructure for providing uniform radio coverage in wireless networks. Indeed, fast improving analog FO links will serve such networks well. In this article, we will analyze the requirements for such a system. >

Wireless: growth engine for advanced global telecommunications

Abstract: Wireless access and new wireless network architectures are rapidly transforming global telecommunications Already at a cost-performance level with conventional wireline technology, mobile cellular and personal communications networks are well entrenched around the globe Wireless has achieved its performance through the innovative application of a range of technologies including smart antennas to increase coverage and performance In the near future, the seamlessly integrated wired and wireless global networks based on international standards will emerge to deliver a profusion of services and provide access to broadband networks