Showing papers on "Key distribution in wireless sensor networks published in 1998"

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/.

Wireless integrated sensor network using multiple relayed communications

Abstract: Wireless integrated miniature sensing stations which can be organized into a communicating network allow sensitive detection and analysis of vibration, infrared radiation, sound, or other physical signals indicative of an intruder or condition to be monitored over a wide area. The sensing stations operate on low power and include a sensor or sensors, a digital signal processor, a microprocessor, and a wireless transceiver for communication. Network communication is facilitated by multiple relayed transmissions from station to station.

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.

Wireless sensor networks

Abstract: Advances in commercial IC fabrication technology have made possible the integration of wireless transceivers, CMOS signal processing, and sensing in one integrated circuit package. Combination with actuation is also possible. This amounts to a low-cost means to link communications and computer networks to the physical world, and may have profound consequences in such diverse areas as security, process control, planetary exploration, and medical monitoring and diagnosis. We outline the system design issues for a distributed sensor network, in which each node has a limited energy supply and relatively low data rate link. The nodes must establish a synchronous multi-hop network, determine locations, and cooperate for such purposes as beamforming and passing messages to the outside world.

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.

System and method for customizing wireless communication units

Abstract: The present invention relates to a system and a method respectively for customizing wireless communication units (10) for use in wireless communication systems. A wireless generic communication unit (10) includes means enabling establishment of contact with a switching arrangement (20) and handling means comprising program executing means (8). Software relating to the wireless communication units is provided in a number of storing means (5, 6, 7) accessible over a global data communications network. Location information is provided, and, with use of said location information, software relating to a particular generic communication unit (10) is downloaded via said switching arrangement using the global data communications network to the communication unit (10). The invenetion also relates to such a generic communication unit.

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.

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.

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.

Distributed network protocols for wireless communication

Abstract: This paper describes a network design strategy that focuses on energy conservation. This position-based network protocol is optimized for minimum energy consumption in wireless networks that support peer-to-peer communication. Given any number of randomly deployed communication nodes over an area, we show that a simple local optimization scheme executed at each node guarantees strong connectivity of the entire network and attains the global minimum energy solution for both stationary and mobile networks.

Method for bandwidth efficient multiple access wireless communication

Abstract: A method for wireless communication utilizes available channel bandwidth when multiplexing a plurality of user signals over a communication channel. The method utilizes signal power characteristics as a signature to multiplex and de-multiplex the plurality of signals applied to the communication channel. Many wireless communication applications are required to utilize a limited, assigned frequency range. Modulation of digital information in such a limited bandwidth is a critical factor in determining the data transferred through the wireless communication channel. The present invention provides for multiplexing of a plurality of digital data sequences over a wireless communication channel having a fixed frequency range. The method provides for a base station which dynamically assigns signaling power parameters to each remote device which is optimally bandwidth-efficient for present signal traffic loads and for present received power conditions. Depending upon a number of factors, the method improves channel bandwidth utilization by factors of two to three over presently known methods. The communication method may be applied to many communication applications wherein a plurality of diverse user signals are multiplexed onto a single communication channel. Exemplary of such applications are wireless voice communication, e.g. digital cellular telephony and wireless data communications, e.g. wireless computer networking.

Low-power wireless beaconing network supporting proximal formation, separation and reformation

Abstract: A low power wireless communication (personal LAN) system (100) includes a plurality of wireless devices (105, 107, 109, 111) with each wireless device including a radio transceiver The radio transceiver may take the form of an insertable card (117) that fits within a slot in the wireless device The plurality of wireless devices (105, 107,109, 111) establishes a wireless network (100) with at least two of the plurality of wireless devices (105, 107, 109, 111) share beaconing responsibilities to coordinate operation of the wireless network (100) One of the plurality of wireless devices (105, 107, 109, 111) may separate from the wireless network to become a separated wireless device In such case, at least one of the wireless devices attempts to reestablish communications with the separated wireless device The wireless devices (105, 107, 109, 111) may establish the wireless network when proximate to one another and operating at a lower power level while continuing operation at a higher power level

Emerging wireless broadband networks

Abstract: The rapid evolution of mobile wireless access networks toward multimedia support with QoS provision forces the development of advanced wireless broadband systems with high reliability and high data rate. To achieve this goal, new system design concepts with increased system capacity will be required. In that context, ATM is becoming a major infrastructure, receiving a lot of attention for telecommunication systems since ATM networks can most effectively support wireless access systems. Wireless ATM systems have low transmission cost, flexible functionality, mobile ATM protocol, and radio access layer protocols. This article overviews the various wireless broadband systems studied at 5, 19.37, 40, and 60 GHz by European Union funded projects within the ACTS program. Moreover, related standardization activities and network evolution are also addressed.

Wireless communication service management

Abstract: Network resources associated with a wireless communication network are assigned to a wireless communication device in accordance with its device type and required service type. A profile is associted with each wireless communication device, and includes a travelling class mark field which identifies the device type of the wireless communication device, and a service class mark field which identifies the required service for the wireless communication device. Different wireless communication devices are accomodated via different profiles. The profiles are permanently stored at a service control point which is accessible to a plurality of mobile service centers.

System and methods in a dual mode wireless system for transmitting rescan command based on detected network conditions

Abstract: A dual-mode wireless telephone communications system, having a digital wireless communications system (e.g., CDMA) and a second wireless communications system, selectively outputs a rescan command from the digital wireless system to at least one selected dual-mode wireless telephone. The digital wireless communications system outputs the rescan command based on a detected traffic condition in the digital wireless system. The rescan command, output to the selected dual-mode wireless telephone via a digital wireless signaling channel, instructs the selected dual-mode wireless telephone to register with an alternative wireless communications system (e.g., AMPS) when the dual-mode wireless telephone is in an idle state. Hence, the digital wireless system can selectively limit access to the CDMA system by dual-mode telephones using proactive rescan commands that avoid the necessity of hard handoff or call transfer procedures normally encountered when initiating a wireless telephone call on the digital wireless communications system.

Experiences with a Mobile Testbed

Abstract: This paper presents results from an eight-day network packet-trace of MosquitoNet. MosquitoNet allows users of laptop computers to switch seamlessly between a metropolitan-area wireless network and a wired network (10 Mbit/s Ethernet) available in offices and on-campus residences. Results include the amount of user mobility between the wired and wireless networks, the amount of mobility within the wireless network, an examination of application end-to-end delays, and an examination of overall packet loss and reordering in the wireless network. We find that the average mobile host switches between the wired and wireless networks 14 times during the trace and moves within the wireless network five times. Round trip latencies in the wireless network are very high, with a minimum of 0.2 seconds. Even higher end-to-end delays, of up to hundreds of seconds, are due to packet loss and reordering. These delays cause users to change their usage patterns when connected to the wireless network. We conclude that latency is a critical problem in the wireless network.

Wireless communication system having network controller and wireless communication device connected to digital communication line, and method of controlling said system

Abstract: Data communicated on one wireless channel is converted and communicated via a wired line. Alternatively, data communicated on a plurality of wireless channels is bundled and communicated via a wired line using a number of channels smaller than that of the wireless channels. In a case where another wireless communication apparatus wishes to use a wireless communication channel when a plurality of wireless channels are being used for communication, some of the plurality of wireless channels are released, thereby making it possible for the other communication apparatus to perform communication even when communication is being carried out using the plurality of wireless channels. When communication by the other wireless communication apparatus subsequently ends, communication on the original number of wireless channels is resumed.

Wireless multi-site networking using signaling and voice-over-IP

Abstract: The invention relates to methods and apparatus for wireless multi-site networking using signaling and voice over Internet protocol. The apparatus includes a wireless portable terminal, a controller for controlling communications equipment, wireless base stations, a computer network, and signaling devices. The wireless portable terminal is registered to a home controller when within a home coverage area, and the wireless portable terminal is registered with a remote controller when within a remote coverage area, thereby allowing the wireless portable terminal to roam from the home location to the remote location using a home wireless base station and remote wireless base stations, respectively, with the ability to make and receive calls via its home directory number.

System and methods for controlling access to digital wireless network in a dual mode wireless system

Abstract: A dual-mode wireless communication system, having a AMPS-based wireless system and a CDMA-based wireless communication system is configured for transmitting digital wireless telephone signals by selectively transmitting a sync channel into a selected propagation region at a power level that is undetectable by digital telephones located within the selected propagation region. The transmission of the sync channel signal at the undetectable power level causes the dual-mode digital telephone to search for the alternative AMPS-based analog system, limiting access by the dual-mode digital telephones. Hence, the dual-mode wireless communication system can limit access to the digital communication system, for example, to prevent the occurrence of hard handoff with an adjacent analog system, or to reduce usage in a congested sector.

Efficient communication strategies for ad-hoc wireless networks (extended abstract)

Abstract: An ad-hoc wireless network is a collection bile hosts forming a temporary network wi any established infrastructure or centralized This type of network is of great importan in situations where it is very difficult to provide the necessa ture, but it is a challenging task able communication within such a we model and analyze the perforn controlled ad-hoc wireless networks: bile hosts are able to change their concentrate on finding schemes for ro tations in these networks. In general find a nl-‘-approximation for any constant E possible strategy for routing a on n mobile hosts. However, we allow ourselves to consider slightly less ge efficient solutions can be found. We first demonstrate that there is a n tributed schemes for handling node-to-no on top of which online route selection and gies can be constructed such that the p class of schemes can be exploited in a near routing permutations in any static power-car network. We then demonstrate to the important case of routin randomly in a Euclidean space, asymptotically optimal for any

A channel selection method of a wireless communication system

Abstract: To provide a channel selection method of a wireless communication system which enables a wireless station to select a wireless channel dynamically even when there are but an insufficient number of wireless channels, a channel selection method of selecting a wireless channel from a plurality of wireless channels prepared for the wireless communication system comprises: a channel search step (202) of checking whether any one of the plurality of wireless channels is left unused by other wireless stations of the wireless communication system or not; a sharing channel selection step (207) of selecting a wireless channel to be shared from wireless channels under use of the other wireless stations, said sharing channel selection step being performed when every of the plurality of wireless channels is found (205) to be under use of one of the other wireless stations at the channel search step; and a link establishment step of establishing the wireless link by sharing the wireless channel selected at the sharing channel selection step.

Universal wireless communication system, a transmission protocol, a wireless communication station, and a radio base station

Abstract: A universal wireless communication system comprising at least two wireless subsystems is proposed which is operated at the edge of spectral efficiency while at the same time allowing wireless communication stations to operate such that optimal power saving is obtained under acceptable transmission conditions. A radio base station of one of the subsystems measures whether a wireless communication station of another one of the subsystems causes adjacent channel interference in a channel its own subsystem. If so, the radio base station commands the wireless communication station of the other substation to adjust its spectral transmission characteristic such that the transmit spectrum becomes narrower. If no interference is detected the wireless communication station of the other subsystem is allowed to broaden its spectrum so that a less complex transmit signal processing, such as filtering, can be applied and thus power saving is achieved.

Multicasting in energy-limited ad-hoc wireless networks

Abstract: We address the problem of multicasting in military "ad-hoc" wireless networks. Since such networks lack a fixed cellular infrastructure, multicast algorithms that are based on the availability of fixed, known topologies cannot be used effectively. Even when the locations of the nodes are fixed and known, the properties of the wireless medium create a networking environment that is vastly different from that of wired networks, and for which the multicasting problem has scarcely been addressed. Specifically, the broadcast nature of wireless transmission and the dependence of range on the transmission power create new opportunities for multicasting that need to be traded off against the interference caused by such transmissions. We address the ways in which the wireless network characteristics, as well as the constraints of limited energy, affect the multicast protocol operation. Preliminary trade-offs are provided, and future research directions are outlined.

Wireless LAN system and method of driving the same

Abstract: There is provided a wireless LAN system including a wireless terminal which transmits a frame to and receives a frame from other wireless terminals for connecting wireless channel therebetween, and then transmits data to and receives data from the other wireless terminals through the wireless channel. The other wireless terminals stop transmission on receiving the frame from the wire terminal. The wireless terminal is designed to transmit a frame to and receive a frame from the other wireless terminals at a first data transfer rate for connecting wireless channel therebetween, and thereafter transmit data to and receive data from the other wireless terminals at a second date transfer rate greater than the first data transfer rate. The above-mentioned wireless LAN system ensures that wireless channel connection by means of RTS frame or CTS frame is established at a constant data transfer rate, for instance, at 2.0 Mbps, and data is transferred at a high rate, for instance, at 4.8 Mbps. Hence, when data is to be transferred at a high rate in an IEEE 802.11-standardized wireless LAN network area, a wireless terminal which transfers data at a low rate can surely realize establishment of wireless channel connection, resulting in that a problem of hidden wireless terminals can be solved.

Apparatus method and systems relating to a wireless geographical positioning system including a system for monitoring and analyzing characteristics of a wireless telecommunications network

Abstract: Apparatus, methods and systems related to, or employing, an event detector that causes a wireless telecommunications network to trigger a request to a wireless positioning system upon detecting a predefined event associated with a Mobile System (MS); the wireless positioning system is operable to determine and communicate the geographic location of the MS to the wireless telecommunications network in response to receiving the request. A system for monitoring and analyzing characteristics of a wireless telecommunications network can advantageously employ the event detector to log data associated with each occurrence of a predefined event. The data can be displayed on a video terminal, for example, as a graphical representation of the data; the graphical representation can be an overlay of the data on a topographical representation of at least a portion of the wireless telecommunications network, whereby the characteristics can be used to troubleshoot and/or improve the operation of the wireless telecommunications network.

RDRN: a prototype for a rapidly deployable radio network

Abstract: This paper reports on the initial implementation of an experimental wireless ATM network architecture called RDRN (Rapidly Deployable Radio Network) The RDRN architecture consists of two types of transportable nodes, remote nodes (RNs) and edge nodes (ENs), which utilize GPS-derived location information to rapidly configure themselves into a high capacity wireless network operating at 1--10 Mb/s over distances as far as 10 kilometers The initial prototype has been deployed and early experiments have been conducted to validate hardware, software, and protocol design and implementation In addition to describing the RDRN architecture and protocols, this paper details experiences at the DARPA GLOMO '97 demonstration of the RDRN project