Showing papers on "Communications system published in 1991"

Interactive multimedia presentation and communications system

Abstract: A system is provided for interactively and selectively communicating particular multimedia presentations to each of a plurality of subscribers along a CATV cable network. The subscriber communicates his selections, both for viewing particular presentations from a menu and for transactions with respect to the information and products being viewed, by entering codes on his Touch-Tone telephone pad. Subscriber input signals are communicated as digital signals through the intercommunications network and response signals are generated, ultimately as analog TV signals for viewing by the subscriber.

Cdma microcellular telephone system and distributed antenna system therefor

Abstract: A code division multiple access (CDMA) communication system in which cellular techniques are utilized in a wireless Private Branch Exchange (PBX) environment. A microcellular arrangement is defined in which a base station (10) communicates user information signals using CDMA communication signals with subscriber terminals. A distributed antenna system (26) is utilized in the system to provide multipath signals which facilitate signal diversity for enhanced system performance.

A physical mobile radio channel model

Abstract: A model is presented for the time- and frequency-selective outdoor mobile radio channel. which is based on the physical process of wave propagation in a statistical fluctuating medium. The reduction of this complex scattering problem to a set of relations containing the pertinent statistics for conducting communications system analysis is developed. Characteristics of the propagation process, e.g., delay power spectra, amplitude distribution (Nakagami-m-distribution), and correlation functions, are derived in parameterized form from physical considerations. The method allows a classification of real configurations (environments) into several classes and the extraction of the relevant parameters in direct comparison with measured data. The method is applied to typical channel situations in Switzerland. The mathematical modeling of the classes is demonstrated. >

Statistical channel impulse response models for factory and open plan building radio communicate system design

Abstract: Statistical radio channel impulse response models are presented for the analysis and design of wireless factory and open plan office communication systems. The models incorporate first- and second-order statistics to characterize the discrete impulse responses of indoor radio channels for both line-of-sight (LOS) and obstructed (OBS) topographies. The effects of large-scale transmitter-receiver separation distance, small-scale receiver movement, and models for the correlation of multipath component amplitudes over 1 m local areas are developed from 1.3 GHz measurements. SIRCIM, a computer simulator based on the models presented, has recreated multipath power delay profiles and CW fading profiles that are representative of measured data. Large-scale models for path loss are implicitly included in this work. >

Life-cycle cost and economic analysis

Abstract: Concepts and theory - system life-cycle concepts economic and cost concepts interest formulae and equivalence alternatives and decision-making decision evaluation theory methodology and applications life-cycle costing methodology estimating cost and economic elements evaluation errors in estimating life-cycle economic evaluations life-cycle optimization of alternatives life-cycle cost in program evaluation case studies communication system procurement repairable equipment system design.

Presentation player for an interactive digital communication system

Abstract: A presentation player is described for use in an interactive digital communications system which may selectively communicate particular multimedia presentations to each of a plurality of subscribers along a CATV cable network, or other communications network. The player is part of a digital interactive system that distributes information representing requested presentations in the form of digital data on distribution channels to a plurality of presentation players located along the communications network. Each of the subscribers has a television set connected to one of these presentation players. The digital data is uniquely addressed to a particular subscriber and is processed by his corresponding presentation player to produce analog TV signals comprising the multimedia presentation. The presentation player automatically tunes itself to a distribution channel and can process data which include motion video sequences, background music, and real-time live video images, in addition to still-video images with audio commentary. The presentation player of the present invention comprises a converter capable of receiving the distribution channel frequencies and selecting one of those frequencies for further processing of digital data transmitted thereon.

Progressive gaming control and communication system

Abstract: In order to provide a progressive gaming system with greater speed, flexibility and reliability a communication unit is used to control the information transmitted between a group of gaming machines and a progressive controller. The communication unit collects coin-in information from each of the gaming machines and transmits this information to the progressive controller in response to periodic poll signal signals from the progressive controller.

Versatile RF data capture system

Abstract: A data capture system is disclosed as comprising a plurality of client data collection terminals, and a server station. Each terminal including a mechanism for collecting data, a dynamic addressable memory and a first controller operating on data formatted in a first style. The server station comprises mass memory, which is larger than the dynamic addressable memory of a terminal for storing data to be used by the data collection terminals, an addresser responsive to a memory altering request for addressing the mass memory and a second controller operating on data formatted in a second style different from said first style. The data stored in the dynamic addressable memory is formatted in the second style. A communication system interconnects the server station and each of the plurality of client data collection terminals. The first controller of each client data collection terminal is responsive to a need for further data to generate a memory altering request and for actuating the communication system to transmit the generated request to the server station. The request is generated to identify its terminal and the particular needed data. The second controller of the server station is responsive to the transmitted request to address and retrieve the needed data from the mass memory before actuating the communication system to transmit the needed data back to the requesting terminal as identified by the request.

Method and apparatus for managing and facilitating communicationsin a distributed heterogeneous network

Abstract: A data communication method and apparatus is presented that allows communication in a distributed heterogeneous network. Communications managers reside in local processing environments and are responsible for interfacing local end users with the remainder of the heterogeneous network. Each communications manager receives distribution units from end users, the distribution units being assigned various priority levels and levels of assurance. Within each communications manager, an adjacent communications manager is determined in accordance with a communications path to a destination for the distribution unit. The distribution unit is then configured according to a network protocol stack existing between the communications manager and the adjacent communications manager, and the distribution units are transmitted according to priority. Each communications manager can have any number of adjacent communications managers each communicating through different network protocol stacks. Also described is load distribution among a complex of processors that share common functions, as well as control of information flow between adjacent communications managers.

Data communication system with communicating and recharging docking apparatus for hand-held data terminal

Abstract: In an exemplary embodiment, portable data devices can be coupled with a local area network at any of a multiplicity of points and integrated into the system on a dynamic basis. The preferred system is highly flexible and closely adaptable to changing needs of an individual user. For example, unitary multiple docking devices each receiving a plurality of handheld computerized data terminals may be chained in a series to a single primary controller which may have a further LAN channel including an auxiliary unit which may supply charging power to a further series of multiple docking devices, added to the system as needed. A preferred auxiliary unit is capable of handling two-way communication without the provision of a direction control line in the channel. A preferred LAN system may have unitary printed circuit boards or other rigid network pathways provided with multiple docking receptacles. The control for the LAN system will automatically establish identities for randomly added devices.

Method and apparatus for selecting a serving transceiver

Abstract: A radio communication system selects a serving transceiver for a remote unit by generating and using a center of mass location estimation. The radio communication system collects uplink and downlink signal characteristics, including impaired signals caused by co-channel interference, from a set of transceivers, including those adjacent to and non-adjacent to the candidate transceiver and remote unit, to aid in the estimation of the remote unit's location within the radio communication system. Using the uplink and downlink signal characteristics, the radio communication system determines weighted coordinates related to predetermined coordinates and the signal characteristics which are used to produce a first and second center of mass coordinate estimation. The radio communication system then selects the serving transceiver to be the transceiver whose predetermined coordinates are closest to the first and second center of mass coordinate estimation.

A method of operating a communications system, a communications system and a secondary station for use in the system

Abstract: A method of operating a communications system, particularly a FDM-TDD cordless telephony system, in which, in order to expedite handover, a portable secondary station builds up a record of the status and quality of the other FDM channels in the system by every 1 in n (where n is an integer greater than one) TDD frames monitoring another FDM channel. The value of n is adaptive in that, as the quality of its existing channel deteriorates, the value of n decreases, thereby updating its record more rapidly. At handover, the secondary station is able to choose immediately an acceptable alternative channel, thereby avoiding the time overhead of scanning all the other FDM channels.

Combination head-protective helmet & communications system

Abstract: A generally hands-free, voice communication system in combination with a head-protective helmet. The helmet protects the wearer's head and the communications system permits voice communications between journeyman personnel, e.g. firefighters, police, military, industrial, hazardous material handling personnel, in relatively close proximity with each other and between journeymen and a group leader; and the group leader's communication system to also permit relatively long-range communication between the group leader and a relatively distant communications center such as a fire engine or distant fire company, base station or repeater.

Spread spectrum communications system

Abstract: A spread spectrum communication system for direct sequence transmission of digital information having a modulation format which is particularly suitable for indoor communication within residential, office and industrial structures. The modulation format combines BPSK or MSK spreading with FM carrier modulation by data bits and a carrier frequency shift whose magnitude is related to both a chip rate and a spreading sequence length. The carrier, chip clock and data clock are all synchronous and the sequence length is an integral submultiple of the bit length. The system reduces the frequency error between the transmitter chip clock and the receiver chip clock to permit the elimination of a code phase tracking loop in the receiver to reduce the receiver complexity. The receiver has an extended dynamic range which makes possible the reception of very strong signal without an automatic gain control loop (AGC) as well as reducing the time needed for code phase acquisition. The transmission system is highly resistant to CW jamming and short distance multipath effects.

Performance of binary and quaternary direct-sequence spread-spectrum multiple-access systems with random signature sequences

Abstract: The performance of synchronous and asynchronous, binary and quaternary (with and without offset) direct-sequence spread-spectrum multiple-access (DS/SSMA) communication systems using random signature sequences and arbitrary chip waveforms is investigated. The average probability of error at the output of the correlation receiver is evaluated using a characteristic-function approach for these systems. Numerical results are presented that illustrate performance comparisons between systems using random and deterministic signature sequences, synchronous and asynchronous systems, systems with rectangular or sinewave chip waveforms, and binary and quaternary systems with the same data rates and bandwidth. In all cases, the accuracy of the Gaussian approximation is also examined. >

ATM communication system with optimal traffic control by changing the allocated bandwidth

Abstract: An ATM communication system including an ATM switching network which includes a plurality of ATM exchanges and controls exchanges among a plurality of terminal equipment and a management apparatus which manages the traffic in the ATM switching network; the ATM switching network including a notifying unit which notifies the terminal equipment of the allocable bandwidth which can be used in accordance with the amount of traffic in the ATM switching network; when the notified allocable bandwidth is a bandwidth which can be used for their communication, the terminal equipment starting the communication in the range of that bandwidth.

Broadcast synchronized communication system

Abstract: A communication system in accordance with the invention employs a broadcast signal for synchronization of the transmitters and receivers in the system without use of a special base transmitter for synchronizing signal transmissions. Each transmitter having a pre-assigned time slot counts from a synchronizing index which is inherent in or added to the broadcast signal to determine when to transmit. The receiver of receivers similarly count from the synchronizing index to determine when to look for specific time slice transmissions.

Communications system and method for bi-directional communications between an upstream control facility and downstream user terminals

Abstract: Cordless telephones generate cell relay packets. Packets from each cordless telephone are polled by an upstream polling unit avoiding multi-unit interference. Cell packets are transmitted via a cable TV system. Radiated frequencies of the cordless telephones are shifted in frequency as they enter or leave the TV feeder cable to allow frequency reuse. The upstream polling unit appends header information on the cell packets and converts them into standard SONET ATM protocol packets. The cell relay packets are switched by a cell relay type switch to create a cost-effective, alternative telephone system.

Intra-cell call hand-over in radio communication systems with dynamic channel allocation

Abstract: The intra-cell call hand-over technique of this invention is characterized by the use of channel information from both base station and subscriber terminal in determining a standby radio traffic channel upon which to hand over a call. Communication between the base station and subscriber terminal is carried out on an inband or associated signalling channel for the selection of the standby traffic channel. The standby radio channel is the channel, which, of a set of channels under consideration by the subscriber terminal, contains the least amount of interference as measured at the subscriber terminal. The set of channels under consideration by the subscriber terminal is a subset of the entire set of channels allocated to the service. This subset is comprised of those channels having little interference as measured by the base station. The call hand-over technique thereby assures that calls proceed on channels containing little interference from the viewpoints of both base station and subscriber terminal.

Personal emergency response communications system

Abstract: A personal emergency response system in which a hand held portable transmitter (12) activates a base unit (14) interfaced with the telephone network (16) to dial 9-1-1 and permit direct communications with the operator (18) at the public safety answering point even though the user (10) is unable to reach a telephone (36). The transmitter (12) activates the base unit (14) as well as optional remote units (48) located throughout the user's residence or place of business. The base unit (14) and remote units (48) include speaker-phone communication capabilities which permit two-way communications between the user (10) and the 9-1-1 system operator (18).

ATM communication system

Abstract: A ATM communication system can satisfy various requests from a node system, a link system, and the like, by performing a self-format transform between a format to be transmitted and a format receiving an ATM switch, and using a cell processing function for performing polishing/shaping, counting of passed cells, counting of discarded cells, drop/insertion of OAM cell, and the like.

Method and apparatus for reducing effects of multiple access interference in a radio receiver in a code division multiple access communication system

Abstract: A CDMA system is disclosed which reduces the effects of multiple access interference, thus increasing channel capacity and achieving greater efficiency in the use of a given frequency bandwidth. The signal is received (701) and the codes for the various channels are applied in the usual way to detect the signals in each channel (702-703). The detected signals are then divided (711) into those with a high confidence level ( g l - g m ) and those with a low confidence level ( u l - u k ). The high-confidence signals are then recoded (721-722) and subtracted (727) from the received signal. The codes corresponding to the channels whose detected signals had a low confidence level are then applied (731-733) to the resulting signal to derive improved detected signals for those channels.

Method and system of communication for a non-contact IC card

Abstract: A data communication system includes an external unit, such as a card reader/writer, with the ability of reading and writing data for a recording medium. The recording medium, such as an IC card, transacts signals with the external unit by being coupled electromagnetically in non-contact fashion with the external unit and is supplied power from the external unit. The external unit includes a first data processor, a first electromagnetic transducing coil for the electromagnetic coupling with the medium, a carrier wave generator connected to the first coil for generating a carrier for transmitting a signal to the recording medium, and a received signal discriminator. The recording medium includes a second data processor, a second electromagnetic transducing coil for the electromagnetic coupling with the external unit, a switching circuit connected to the second coil for varying the load impedance of the second coil in response to a signal to be sent to the first coil, and a received signal detecting circuit. The data signal from the recording medium is demodulated for the carrier frequency from the external unit in response to the data signal, and transmitted to the external unit. The recording medium includes circuits which detect a variation in the power voltage supplied through the electromagnetic coupling and feed it back electromagnetically to the external unit.

Multicomponent wireless system with periodic shutdown of transmitting and receiving modes

Abstract: A communications system comprises a plurality of transceivers capable of transmitting and receiving data from other transceivers in the system. At least one transceiver functions as a control module. Communication between the control module and the remainder of the communications modules occurs by consecutive communication between individual communications modules in the system. This means that low power transceivers can be used to form a system having a long range capability.

Broadband CDMA for personal communications systems

Abstract: Multipath propagation in a broadband CDMA environment is described. A propagation model for broadband spread-spectrum signals is presented. Experimental results relating to the sharing of the band by fixed service microwave users and mobile personal communications network (PCN) users are discussed. Field tests indicate that PCN systems can provide high-quality communications when sharing the spectrum with fixed-service microwave systems in suburban and urban areas. >

Router using remote address resolution to enable bridge like data forwarding

Abstract: A communications system is disclosed, having a first communications link, a second communications link, a first end station attached to said first communications link, a first packet forwarding apparatus attached to the first communications link, a second end station attached to the second communications link, and a second packet forwarding apparatus attached to the second communications link. Each packet forwarding apparatus routes packets it receives having destination address equal to a data link destination address of the apparatus, and bridges all other received packets. When the first end station wishes to send a packet to the second end station, it first transmits an ARP request message to learn the data link address of the second end station. The first apparatus receives the ARP (Address Resolution Protocol) request message, and determines that the end station for which a data link address is requested is attached to a remote communications link. The first apparatus requests the second apparatus to transmit an ARP request message to determine the second station's address, and to relay the ARP response back to the first apparatus. When the first apparatus receives the ARP response, it forwards the response to the first end station. The first end station transmits subsequent packets to the second end station, using the data link address of the second end station as a data link destination address. These subsequent packets can be bridged by any intermediary apparatus between the first end station and the second end station.

High-speed transport components

Abstract: An overview of research of high-speed transport components is given. High-speed protocols as well as high-speed implementations are considered. The use of parallelism to increase the performance of communication nodes is considered. A parallel implementation of Open Systems Interconnection (OSI) protocols on transputer networks based on the parallel concepts discussed is described. Selected performance values of the implementations are presented. The outlook on the design of high-speed transport components for future communication systems is examined. >

Method of controlling handoff in cellular mobile radio communications system

Abstract: When communication is established using a mobile radio terminal, the speed at which the terminal is moving is measured by monitoring the Rayleigh fading of the signal strength. Using this velocity indicative parameter, a threshold level which is used to determine if a handoff is required or not, can be adjusted in a manner which renders the decision process more accurate and minimizes the number of unwarranted handoffs.

Communication system having multiple base stations and multiple mobile units

Abstract: An air-to-ground communications system is described for controlling multiple two way radiotelephone conversations between a large number of aircraft (53) and a network of base stations (51) that are capable of being interconnected to landline telephone networks (54, 116). Plural base station controllers (90) of the system, each dedicated to control one base station (51), are in turn controlled by a single central processor (52). Means are provided for matching each aircraft with an optimal base station to afford it the strongest available communication signals, and for dynamically allocating communication channels between the base stations. The central processor (52) is designed to manage the system by recording and recognizing usage patterns (525-530) and allocating channels to most efficiently use the available radio spectrum among all the aircraft (517, 519).

Data packet alignment in a communication system

Abstract: A communication system provides data packet timing alignment to facilitate soft handoff. A vocoder (315) transmits compressed voice frames to base-stations (130,131) along links (110,112) of variable length, Δ L . The Δ L translates to a delay Δ t in the air-frames to be transmitted by the base-stations (130,131). To compensate for the time delay Δ t , the communication system advances both sets of air-frames to be transmitted by base-stations (130,131) by at least Δ t so that skipping of frames, relative to an air-frame reference (300), during transmission does not occur.