Showing papers on "Wi-Fi array published in 1995"

Propagation Measurements and Models for Wireless Communications Channels To achieve ubiquitous PCS, new and novel ways of classifying wireless environments will be needed that are both widely encompassing and reasonably compact.

Abstract: ireless personal communications could in principle use several physical media, ranging from sound to radio to light. Since we want to overcome the limitations of acoustical com

Broadband wireless system and network architecture providing broadband/narrowband service with optimal static and dynamic bandwidth/channel allocation

Abstract: A wireless broadband communication system architecture is structured to provide an array of narrowband and broadband services to an end user on demand. The bandwidth of delivery is dynamically adjusted to deliver and satisfy service requirements by utilizing the appropriate bandwidth on demand. Bandwidth-on-demand is provided in accord with the invention by rearranging spectrum allocations so that a particular band spectrum is convertibly used to accomplish different purposes depending on present allocations and active applications of the system. The communications system is designed to utilize wireless communication for end point delivery to both fixed and potable terminals. The system supplies basic telephone service, wireless ISDN service, wireless data service, wireless multimedia service and various other wireless broadband service including types of interactive and broadcast video.

Wireless network planning tool

Abstract: A novel and improved method and apparatus for planning a wireless telecommunications network. An electronic representation of wireless telecommunications system can be configured within a given market area and the operation of that wireless telecommunications system simulated. The simulation is performed using a set of databases that contain terrain and population information associated with the market area over which the wireless network in configured. To perform the simulation a composite propagation loss matrix and a demand and service vector are generated using the terrain and population information, as well as the configuration of the wireless telecommunications network. Once the composite propagation loss matrix and the demand and service vector are generated an analysis of the reverse link is performed. Subsequently, an analysis of the forward link is performed. During both the reverse and forward link analysis the multiple iterations of analysis are performed until a stable result is achieved. Upon completion of the reverse and forward link analysis, the results of the simulation are displayed in a graphical manner for examination.

Cellular telephone fraud prevention system using RF signature analysis

Abstract: Apparatus for identifying wireless subscriber units and for determining if access to a communications network should be granted. A plurality of wireless subscriber units each generates a wireless subscriber signal including internal data traits and external signal traits. The internal data traits include an identification code. A RF downconverter is located remote from the wireless subscriber units and receives the wireless subscriber signal. A characterizing device is connected to the RF downconverter and extracts parameters that characterize the external signal traits of the wireless subscriber units. A decision device computes the likelihood that the observed parameters belong to the validated wireless subscriber unit to determine if access to the wireless subscriber service should be granted. The apparatus may be used to prevent cellular telephone cloning fraud.

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.

BAHAMA: a broadband ad-hoc wireless ATM local-area network

Abstract: We describe the theory, design and ongoing prototyping of a wireless ATM LAN/PBX capable of supporting mobile users with multi-Mb/s access rates and multi-Gb/s aggregate capacities. Our proposed LAN consists of network nodes called portable base stations (PBS) providing microcell coverage. The PBSs are designed to be low-cost, compact and high-speed and can be relocated conveniently. We employ a concept of ad-hoc networking in the layout of the PBS-to-PBS interconnection. That is, the PBSs can be distributed in an arbitrary topology to form a backbone network and can be reconfigured with relative ease. The PBS-to-PBS backbone links are high-speed (Gb/s) for supporting high system capacity. Although they can either be wired or wireless, our emphasis is on wireless implementations. The user-to-PBS links, on the other hand, are primarily for mobile access (e.g., 2-20 Mb/s) and therefore are wireless. Wired connections from stationary users to PBSs are also possible. Typical mobile users are assumed to be laptops or notebook computers. Services supported include conventional data applications (e.g., over TCP/IP or SPX/IPX) as well as multimedia (video, voice and data) applications with QoS (quality-of-service) guarantees. A "aireless ATM" concept is proposed so as to provide seamless internetworking with other wired ATM local and wide-area networks. Algorithms and control in our network are highly distributed for simple implementations and ease of mobility management. A new wireless VP/VC concept and a homing algorithm are described to provide ATM cell routing and connections in the network. PBS hardware and software architectures are discussed. Call management, network management and signaling are designed for simplicity, high performance and modular implementations. A fast network restoration scheme is proposed to cope with the potential link or node failures in the ad-hoc network. Error control is addressed taking the unreliable wireless links into consideration. Finally, a prototyping project called BAHAMA (broadband ad hoc ATM anywhere) for demonstrating this network concept is briefly outlined.

Method and apparatus for controlling message delivery to wireless receiver devices

Abstract: A method and apparatus for controlling message delivery to wireless receiver devices can be used for example to condense textual messages intended for a wireless receiver device by abbreviating various words in the message. Thus, a first message addressed to a wireless receiver device (20) is received and stored in a storage medium (14). The received message is then translated into a second message using a pre-defined dictionary associated with the wireless receiver device. The second message is then sent to the wireless receiver device. Thus, the wireless receiver device receives shorter messages conveying the same information as the original message that was to be sent to the wireless receiver device. The translating feature can also be used to code messages or translate messages into a different language.

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.

A wireless broadband ad-hoc ATM local-area network

Abstract: We describe the theory, design and ongoing prototyping of a wireless ATM LAN/PBX capable of supporting mobile users with multi-Mb/s access rates and multi-Gb/s aggregate capacities. Our proposed LAN consists of network nodes called Portable Base Stations (PBS) providing microcell coverage. The PBSs are designed to be low-cost, compact and high-speed and can be relocated conveniently. We employ a concept of ad-hoc networking in the layout of the PBS-to-PBS interconnection. That is, the PBSs can be distributed in an arbitrary topology to form a backbone network and can be reconfigured with relative ease. The PBS-to-PBS backbone links are high-speed (Gb/s) for supporting high system capacity. Although they can either be wired or wireless, our emphasis is on wireless implementations. The user-to-PBS links, on the other hand, are primarily for mobile access (e.g., 2-20 Mb/s) and therefore are wireless. Wired connections from stationary users to PBSs are also possible. Typical mobile users are assumed to be laptops or notebook computers. Services supported include conventional data applications (e.g., over TCP/IP or SPX/IPX) as well as multimedia (video, voice and data) applications with QoS (Quality-of-Service) guarantees. A “wireless ATM” concept is proposed so as to provide seamless internetworking with other wired ATM local and wide-area networks. Algorithms and control in our network are highly distributed for simple implementations and ease of mobility management. A new wireless VP/VC concept and a Homing Algorithm are described to provide ATM cell routing and connections in the network. PBS hardware and software architectures are discussed. Call management, network management and signaling are designed for simplicity, high performance and modular implementations. A fast network restoration scheme is proposed to cope with the potential link or node failures in the ad-hoc network. Error control is addressed taking the unreliable wireless links into consideration. Finally, a prototyping project called BAHAMA (Broadband Ad Hoc ATM Anywhere) for demonstrating this network concept is briefly outlined.

Asymmetric protocol for wireless communications

Abstract: A wireless communications system is arranged to provide data communications services, including error recovery, between at least one wirelessend-user device and at least one one base station. The wireless end user device(s) receives(s) from the base station(s) unsolicited messages indicative of the status of data packets received by the base station(s). The wireless end-user device(s) transmit acknowledgement and request for retransmission messages only upon request, or when all the packets within a block of such packets have been received.

Apparatus for providing access to field devices in a distributed control system

Abstract: An apparatus for accessing field devices in a distributed control system provides non-redundant secondary access to a plurality of field devices that are controlled by a control room. An apparatus also provides redundant wireless to access field devices in a distributed control system having primary access to the field devices provided by hard-wired media that couples the field devices to the control room. The field devices are coupled to a Fieldbus control network. In a first embodiment, each field device is provided with a wireless Fieldbus port that is accessible by a wireless handheld unit or wireless terminal. In a second embodiment, each Fieldbus control network is provided with a field module having a wireless Fieldbus port that allows all devices connected to the Fieldbus control network to be accessed by a wireless handheld unit or a wireless terminal. In a third embodiment, an H2-to-H1 Fieldbus bridge (which may service a plurality of H1 control networks) is provided with a wireless Fieldbus port that allows all Fieldbus devices connected to H1 control networks serviced by the H2-to-H1 bridge to be accessed by a wireless handheld unit of a wireless terminal. In a fourth embodiment, a bridge/converter provides an interface between older analog control room components and newer Fieldbus field devices.

Two-way wireless data network having a transmitter having a range greater than portions of the service areas

Abstract: A two-way data network includes a broadcast control sub-network and a cellular data sub-network. The broadcast control sub-network includes a few high-power radio transmitters broadcasting into a large service area. The cellular data sub-network covers the large service area by a number of base stations each servicing a relatively small area. The wireless terminals of the two-way data network monitors the messages in a broadcast control channel at pre-assigned periodic time slots and remain in "sleep" mode at other times. A packet radio transceiver in the wireless terminal sends data to, and receives data from, the cellularized base stations. The broadcast control sub-network is used to notify the subscriber the receipt of a message. In responding to the notification, the location of the subscriber's wireless terminal is make known, thereby eliminating conventional tasks such as location and mobility management tasks and allowing wireless terminals to be low power. Communication between the cellular base stations and the wireless terminals achieves high data rate, low latency and high capacity.

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.

Preferred system selection techniques for mobile terminals

Abstract: Method for selecting a preferred system for wireless communications with a mobile terminal or subscriber. To select a preferred system for wireless communications with a mobile terminal or subscriber using a mobile terminal, a range of operating frequencies are scanned to detect wireless systems. Each time a wireless system is detected, a determination is made as to whether the detected wireless system is a most preferred system or a lesser preferred system for the mobile terminal or subscriber. If the detected wireless system is determined to be the most preferred system, scanning is terminated and the detected wireless system is selected for wireless. If, however, the detected wireless system is determined to be one of the lesser preferred systems, selection information for the detected wireless system is stored in a memory subsystem of the mobile terminal and scanning continues. Upon completion of the scanning, if no wireless system has been selected as the most preferred system, a highest ranking lesser preferred system is selected using the selection information stored in the memory subsystem for wireless communications.

Method and apparatus for a wireless local area network

Abstract: A protocol for wireless local area network communication between a base stationary unit (30) and a plurality of wireless terminals (30a, 30d) is disclosed. The main features of this protocol is based upon channel reservation requests by active wireless terminals. Contention is resolved and authorization is granted with data message signals transmitted by the authorized wireless terminal either immediately for asynchronous service or periodically for a time-based service. The system further provides for the base stationary unit to query the receipt of the data message signal by the wireless terminal authorized to receive the transmission. If no response signal is received, then the base stationary unit would authorize for itself transmission of the data message to relay it, either 'over the air' or via wired connection to another base stationary in another data cell. The synchronous nature of the method provides for power saving by allowing the receiver and/or transmitter to be powered down during idle and other time slots.

The design & implementation of a hybrid handover protocol for multi-media wireless LANs

Abstract: c ACM 1995. Permission to copy without fee all or part of this material is granted provided that the copies are not made or distributed for direct commerical advantage, the ACM copyright notice and the title of the publication and its date appear, and notice is given that copying is by permission of the Association of Computing Machinery. To copy otherwise or to republish will require a fee and/ or speci c permission. Abstract

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.

Mobile wireless network system simulation

Abstract: This paper describes an advanced simulation environment which is used to examine, validate, and predict the performance of mobile wireless network systems. This simulation environment overcomes many of the limitations found with analytical models, experimentation, and other commercial network simulators available on the market today. We identify a set of components which make up mobile wireless systems and describe a set of flexible modules which can be used to model the various components and their integration. These models are developed using the Maisie simulation language. By modeling the various components and their integration, this simulation environment is able to accurately predict the performance bottlenecks of a multimedia wireless network system being developed at UCLA, determine the trade-off point between the various bottlenecks, and provide performance measurements and validation of algorithms which are not possible through experimentation and too complex for analysis.

User out-of-range indication for digital wireless systems

Abstract: A system for notifying users of digital wireless communications that a mobile unit is moving out of range and communication is about to be lost. The system inserts an audible indication as the received signal strength varies. The audible indication can be in the form of noise which is inserted in such a manner that a digital mobile unit mimics the behavior of an analog mobile unit which is moving out of range, in order to provide a readily identifiable indication to the user that the wireless handset is about to go out of range. Such a system can be used to indicate to both users of wireless units, and to telephone users which are in communication with wireless units, that communication is about to be lost.

End-to-end test strategy for wireless systems

Abstract: This paper proposes an end-to-end test strategy for wireless systems described by using wireless microcell as a vehicle. It presents a framework for resting digital and radio frequency (RF) boards in a wireless system and provides an integrated solution. The test strategy is based on two concepts: using boundary-scan for digital testing, and using boundary-scan to provide a gateway for DSP-based functional testing of RF circuits. The test signals are generated within the system and the test control and verification are also provided by the system leading to system self-test.

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.

Controlling power and access of wireless devices to base stations which use code division multiple access

Abstract: The invention relates to the use of CDMA techniques. Data signals to be transmitted from a plurality of wireless devices are spread across a common bandwidth. The data signals are received by a base station as a composite spread signal. The base station partially despreads the composite spread signal with unique codes to extract data signals from individual wireless devices. The data rate and quality of service requirements for each wireless device are used to calculate a power factor and a control signal is sent to control the power from a particular wireless device. In addition, a probability of transmission value is calculated based on an equivalent current load value and an equivalent population value. The probability of transmission value determines whether a particular wireless device is allowed access to an uplink frequency channel.

System and method for switching control between a host computer and a remote interface device

Abstract: The present invention relates to a wireless interface device and more particularly to a wireless interface device for interfacing with a host computer connected in either a wired or wireless local area network. Once a connection is made between the wireless interface device and a host computer, the host computer is under the control of the wireless interface device. In order to provide a convenient way to return control back to the host computer, a hot icon is provided on the wireless interface device which, in response to a pen-down event, automatically returns the control back to the host computer.

Wireless LAN system and base station apparatus

Abstract: A wireless LAN system which allows the transmission and reception of various data without lowering the transmission efficiency and the transmission quality even in an overlapping environment of areas of a plurality of wireless LANs and a base station apparatus therefor are provided. The wireless LAN system has a plurality of wireless LANs including base stations and wireless terminal devices, and the base stations and the wireless terminal devices in the wireless LANs communicate while sequentially hopping carrier frequencies to conduct the intercommunication between the base stations in the wireless LANs through inter-base station communication units. Each base station includes a unit for transmitting and receiving a specific frame to and from other base stations through the inter-base station communication unit to determine whether its own base station is a master base station or not and a unit for assigning different hopping start frequencies to its own base station and other base stations when its own base station is determined as the master base station.

Wireless data: systems, standards, service

Abstract: Wireless data products and services being proposed today include exotic mixes of services and technologies: packet transport over cellular circuits, facsimile service over Cellular Digital Packet Data (CDPD), voice and video over wireless LANs, and everything in between. Data networking terms that seem to have a clear meaning—data-link, network and transport layers; circuit-mode and datagram; connection-less and connection-oriented—in fact have meaning only in context. Thus TCP, a reliable packet transport protocol, is being used in CDMA circuit-mode data to provide a reliable data-link layer for the errorprone wireless link. IP datagrams will be transported over cellular links using dedicated channels with call establishment, possibly per packet. Market demands for timely solutions, competition between alternative technologies and the plethora of alternative fora for standards development are driving wireless data into fragmented directions. The primary constraints come from the limited spectrum, the need for security in the presence of mobility and the size and weight of mobile terminals and devices. Often the optimization for the latter constraints is sacrificed at the altar of the former drivers. Based upon our experience and work with standards and systems we attempt to put wireless data into perspective. We compare and contrast major services and products and identify the choices that were made and why.

Locator and method for a wireless communication system

Abstract: A passive locator and method for a wireless communication system. The locator (56) at base station (12) determines the position and trajectory of wireless terminal (22). The passive locator (56) adjusts azimuthal and elevational angles of a directional antenna (58) until a relative maximum power is detected in the signal transmitted from the wireless terminal (22). A processing circuit (60) determines the trajectory of the wireless terminal (22) by generating and analyzing data that represents the Doppler effect on the signal from the wireless terminal (22).

Screen saver disabler

Abstract: A wireless interface device for interfacing with a host computer connected in either a wired or wireless local area network (LAN). The wireless interface device includes a display that mirrors whatever is being displayed on the host computer to which it is connected. In order to reduce unnecessary LAN traffic, any screen savers running on the host computer are automatically disabled when a radio connection is made between the host computer and the wireless interface device. When the wireless interface device is disconnected from the host computer, the screen saver running on the host computer is automatically re-enabled.