Showing papers on "Wireless published in 1992"

Communication system and methods for enhanced information transfer

Abstract: A communication system (20) is provided with multiple purpose personal communication devices (50 and 150). Each communication device (50 and 150) includes a touch-sensitive visual display (60 and 160) to communicate text and graphic information to and from the user and for operating the communication device (50 and 150). Voice activation (78) and voice control capabilities (76) are included within communication devices (50 and 150) to perform the same functions as the touch-sensitive visual display (60 and 160). The communication device includes a built-in modem (82), audio input and output (52 and 53), telephone jacks (86), and wireless communication (90). A plurality of application modules (100) are used with personal communication devices (50 and 150) to perform a wide variety of communication functions such as information retrievable, on-line data base services, electronic and voice mail. Communication devices (50 and 150) and application modules (100) cooperate to allow integrating multiple functions such as real time communication, information storage and processing, specialized information services, and remote control of other equipment into an intuitively user friendly apparatus. The system (20) includes both desktop (150) and hand-held communication devices (50) with the same full range of communication capabilities provided in each type of communication device (50 and 150).

Spatial division multiple access wireless communication systems

Abstract: A method and apparatus for increasing the capacity and quality of wireless communication between a plurality of remote users and a base station is disclosed. Using measurements from an array of receiving antennas at the base station, parameters of multiple signals transmitted to the base station from a plurality of users in the same channel are calculated and used to obtain the positions and velocities of the users. The locations and other related signal parameters are used to calculate appropriate spatial demultiplexing strategies, reconstructing the individual transmitted signals from the receiver measurements and reducing interference to acceptable levels. This heretofore unavailable location information is used in solving the hand-off problem. This information is also used to calculate an appropriate spatial multiplexing strategy for simultaneous transmission of signals to users in the same channel. This can be the same as or distinct from the aforementioned receive channel. In combination, the transmit and receive systems establish multiple full-duplex links in the same channel by directively receiving and transmitting signals at the base stations only. This invention can also be implemented at the mobile sites to improve signal quality and to establish point-point communication links between multiple mobile users. Furthermore, implementation of both transmit and receive functions at the base station is not required. A receive-only system base station will still improve received signal quality and therefore capacity in addition to mitigating the hand-off problem.

Method and apparatus for multiple access between transceivers in wireless communications using ofdm spread spectrum

Abstract: A method for allowing a number of wireless transceivers to exchange information (data, voice or video) with each other. A first frame of information is multiplexed over a number of wideband frequency bands at a first transceiver, and the information transmitted to a second transceiver. The information is received and processed at the second transceiver. The information is differentially encoded using phase shift keying. In addition, after a pre-selected time interval, the first transceiver may transmit again. During the preselected time interval, the second transceiver may exchange information with another transceiver in a time duplex fashion. The processing of the signal at the second transceiver may include estimating the phase differential of the transmitted signal and pre-distorting the transmitted signal. A transceiver includes an encoder for encoding information, a wideband frequency division multiplexer for multiplexing the information onto wideband frequency voice channels, and a local oscillator for upconverting the multiplexed information. The apparatus may include a processor for applying a Fourier transform to the multiplexed information to bring the information into the time domain for transmission.

Wireless telephone/satellite roaming system

Abstract: A wireless telephone system capable of servicing a roaming wireless telephone user includes a satellite communications system consisting of one or more orbiting satellites, each carrying a database of users, destination codes and call codes, within a satellite service area, a satellite control center, and a plurality of terrestrial communications links. The system operates by effecting communication between a terrestrial wireless telephone end user transceiver apparatus and a terrestrial communications link via a single relay through a single satellite or a succession of satellites wherein the relay station may be in motion relative to the end user transceiver apparatus and the terrestrial communications link, wherein the orbiting relay station effects the ultimate decision on linking based on stored on-board information and on-board processing, and wherein the end user transceiver apparatus, the orbiting satellite and the terrestrial communications link are operative in cooperation with the on-board database to effect hand-off from a first orbiting satellite to a second orbiting satellite. The satellite system is a single satellite or preferably a constellation of satellites orbiting near the earth, all of which are capable receiving requests for calls and participating in the call routing and call setup on an autonomous basis. The satellites are capable of decoding the calls, switching, handing off of calls to other satellites, and updating databases of users based on information provided by network control.

Wireless access telephone-to-telephone network interface architecture

Abstract: A wireless-access communications system, such as a CDMA cellular radio-telephonesystem (FIG. 2), comprises a packet-switched communications network (202, 207, 201) that interconnects cells (base stations; 202) with each other and with the public telephone network (100). Traffic of individual calls is packetized, and packet-bearing frames (300 in FIG. 7) of a plurality of calls are then statistically multiplexed and frame-relayed through the network to yield the high capacity, efficiency, and speed of traffic transport and handoff required for a CDMA cellular system. At each call processing unit (264 in FIG. 5), individual calls are handled by individual service circuits (602 & 612) which perform speech-processing functions such as coding and decoding, tone insertion, and echo cancellation, and packet-to-circuit-switched-PCM traffic conversion. Processors (602) adapt call processing unit timing to compensate for asynchrony between cells and call processing units and variations in call path transmission delays. Cell-to-cell communications, fixed call path addressing, and packetized control message transfers ensure that the same service circuit handles a call through even multiple soft handoffs (FIGS. 27 - 29) and efficiently communicates simultaneously with all cells involved in the handoff without involvement of system control entities and negative effect on system call-handling capacity. Both coded (packet-switched) and uncoded (circuit-switched) radio-telephone traffic are accommodated side-by-side. Wherever possible, existing and proven technology and component units are used to achieve low cost and high reliability.

Satellite telecommunications system using network coordinating gateways operative with a terrestrial communication system

Abstract: A wireless telephone system (10) capable of servicing a roaming wireless telephone user (30) includes a satellite (22) communications system consisting of at least one orbiting satellite (22); at least one terrestrial-based gateway (12, 14, 16, 18) having access to a database (20) of users, destination codes (telephone numbers); at least one network coordinating gateway (28) within at least one satellite service area (24); a single network control center (25); and a plurality of terrestrial communications links (e.g. 101). The system (10) operates by effecting communication between a terrestrial wireless telephone end user transceiver apparatus (e.g. 501) and a terrestrial communications link (e.g. 101) via a single relay through a single satellite (22) or a succession of single relay satellites (22) wherein the relay station may be in motion relative to the end user transceiver apparatus (501) and the terrestrial communications link (101). The ground-based gateway (28) effects the ultimate decision on linking in cooperation with the network database to effect hand-off from a first orbiting satellite (22) to a second orbiting satellite (22). The single satellite (22) or preferably a constellation of satellites (22) orbiting near the earth need only translate signals from the gateways (12, 14, 16, 18) to the users (30) and from the users (30) to the gateways (12, 14, 16, 18), without satellite-based control.

A portable multimedia terminal

Abstract: A personal communications system (PCS) that centers on integration of services to provide access to data and communications using a specialized, wireless multimedia terminal is described. The possible applications and support systems for such a terminal are outlined. Several of the major design issues behind portable multimedia terminals, including spectrally efficient picocellular networking, low-power digital design, video data compression, and integrated wireless RF transceivers, are discussed. It is argued that optimizing performance in each of these areas is crucial in meeting the performance requirements of the overall system and providing a small, lightweight terminal for personal communications. >

Spot-diffusing and fly-eye receivers for indoor infrared wireless communications

Abstract: A new configuration featured as using spot-diffusing, multiple line-of-sights and fly-eye receivers is proposed for indoor optical wireless communications. Design issues such as suitable light sources, power budget, ambient light interference and fly-eye design are discussed based on simple geometric models. An experiment is conducted to demonstrate the feasibility of the spot diffusing concept. >

Wireless network access for personal communications

Abstract: An explanation of the widely different technological approaches and technologies being proposed for different interpretations of wireless personal communications services (PCS) is presented. Different wireless communications applications and issues surrounding the applications are discussed. Descriptions of the compromises that have been made in developing specific technologies optimized to serve the cordless telephone and the vehicular mobile radio applications are presented. Characteristics of a technology that is aimed at the widespread pedestrian PCS application and environment are outlined. Different wireless technologies that have been aimed at different applications and environments are compared. >

Incoming communications forwarding technique utilizing a called party location indicator

Abstract: A communications signal-transmitting device carried by a communications system user indicates the location of that user relative to other wired or wireless communications devices connected to a communications system. This location indication is utilized by the communications system to forward incoming voice and/or data communications for that user to the other communications device so that the user can receive such communications. As a result, the location of any potential system user is provided and call forwarding for that user is accomplished without the prior art problems associated with activation and deactivation. In the disclosed embodiments which pertain to the forwarding of voice communications in a PBX environment, the communications device is a pager which communicates with the wired or wireless telephone sets connected to the line side of the PBX to provide the PBX with the location of the system user relative to these telephone sets.

Automatically configuring wireless PBX system

Abstract: A wireless PBX system provides ease of installation without site engineering or trial-and-error placement of components within the system. In its basic form, the wireless PBX system consists of only two types of components: a control unit including an radio frequency transceiver; and fixed location terminals, such as telephones and voice/data stations, which also include radio frequency transceivers. Portable handsets are optionally included in the system to allow for customer mobility. Installation of the PBX system is achieved simply by placing the system components in the desired locations at a premises, plugging them into line power, and performing some simple programming steps including a final step of initiating an automatic configuring process. Through this process, the system automatically configures itself for optimum operation in view of the radio environment and placement of components within the system at the customer premises. In the operation of this process, the control unit exchanges various radio messages with the terminals, decides which terminals should also serve as repeaters for linking those more distantly located terminals, and determines the appropriate frame structure for the system. A positive display indication at the control unit, following the end of the automatic configuring process, shows that all terminals have been linked and that the system is operating normally.

Wireless device for verifying identification

Abstract: A wireless communication device using a verification protocol for verifying the identification of the wireless device by a wireless network control station in the presence of eavesdroppers is disclosed. Upon receiving a call request from a wireless device claiming a particular identity, the wireless network control station sends a mask consisting of binary digits in a random order. The wireless device is expected to respond to this mask with a reply that is consistent with both the password contained in the device and the mask. Specifically, the bits of both the password and the mask are "ANDed" and the result transmitted to the wireless network control station as the reply.

SIR-based power control in a CDMA system

Abstract: Power control in the use of direct-sequence code-division multiple-access (CDMA) techniques is addressed. Previous performance analyses of CDMA wireless mobile and personal communications have assumed the ability of power control to equalize the absolute signal powers of users received at each base station. A more practical, although analytically more complicated, uplink power controls technique that uses measurements of the received signal-to-interference ratio. (SIR) instead is studied. A combination of discrete-event link simulation and analysis of the obtained SIR statistics is used to explore the behavior of a CDMA system using SIR-based power control and to obtain performance estimates for such a system under various operating assumptions. The overall results indicate that power control based on SIR has the potential for somewhat higher system performance than power control based on absolute signal strength. >

Integrated wireless telecommunication and local area network system

Abstract: A system combines LAN and telecommunication capabilibes to provide a high speed wireless LAN capability and to simultaneously provide wireless ISDN capability within an office. The LAN and ISDN information is communicated over a common transmission medium. The system also allows a user to interconnect wireless ISDN digital terminals (109,110) to any other ISDN equipment anywhere in a PBX switch system or the public network (130). The system provides for communication of information between wireless LAN units (111,112,113) and ISDN equipment (109,110). For example, this function allows a local computer (112) using a local LAN interface to communicate with a remote computer (131) via ISDN switching facilities (130). Further, the expense of hiding unsightly wiring in an office environment can be avoided, and the cost of moves and rearrangements of equipment can be greatly minimized.

The capacity of wireless communication systems can be substantially increased by the use of antenna diversity

Abstract: For a broad class of interference-dominated wireless systems including mobile, personal communications, and wireless PBX/LAN networks, the authors show that a significant increase in system capacity can be achieved by the use of spatial diversity (multiple antennas), and optimum combining. This is explained by the following observation: for independent flat-Rayleigh fading wireless systems with N mutually interfering users, it is demonstrated that with K+N antennas, N-1 interferers can be nulled out and K+1 path diversity improvement can be achieved by each of the N users. Monte Carlo evaluations show that these results also hold with frequency selective fading when optimum equalization is used at the receiver. Thus an N-fold increase in user capacity can be achieved, allowing for modular growth and improved performance by increasing the number of antennas. >

Slot hopped fd/td/cdma

Abstract: In a wireless frequency and time division multiple access (FD/TDMA) communications system having time-slotted communications channels, there is provided a method of and apparatus for hopping wireless communications. It comprises sequencing slot assignments (SLOT SEQ'R) and sequencing frequency assignments (FREQSEQ'R) such that a multiplicity of frequencies are thereby usable at each site of a cellular FD/TDMA system without regard to local partitioning among surrounding uses thereof. The effect would be probabilistically reduce the interference, not only by the number of hopping frequencies, but by a factor of the number of time slots per frame.

Network control for wireless communications

Abstract: Existing wireless network architectures and the increasing demand for cellular services are reviewed. Wireless network control tasks and the structure of a cellular packet switch (CPS) based on an optical fiber metropolitan area network (MAN) are described. Protocols for moving information through the MAN focusing on handoff, a crucial function of wireless networks, are discussed. The results of an analysis of switch performance as measured by capacity and the distribution of functionality are presented. Several open issues regarding the capability of the CPS to deliver telephone service to wireless terminals, including privacy and security issues, are discussed. >

Wireless communication zone management system

Abstract: A wireless communication system comprising a plurality of antennae, the antennae being arranged in a grid pattern over a communication region, wireless portable terminals located within the communication region for emitting and/or receiving electromagnetic signals via the antennae, apparatus for determining the position of at least one of the terminals within the communication region relative to the grid pattern.

Performance limitations of TDD wireless personal communications with asynchronous radio ports

Abstract: A wireless personal communications system, based on a TDMA architecture, using asynchronous ports (radio base stations) and the TDD (time division duplexing) method is evaluated using computer simulations. It is shown that, without port synchronisation TDD methods cannot achieve the uplink quality obtainable by the FDD (frequency division duplexing) method.

Wireless in-building network architecture and protocols

Abstract: The authors highlight the topology, architecture, and protocols developed for a wireless in-building network based on 18-GHz radio technology. They introduce the requirements of an in-building office environment that involves desktop computing applications and describe a microcellular topology with store-and-forward radio modules that uses time division duplex techniques to organize transmitting and receiving. Unique to the architecture and protocols are methods for coordinating devices with sectorized antennas, for providing high performance in terms of high throughput and low delay, and for compatibility with networking standards. >

Cordless personal communications

Abstract: The role of digital cordless technology in the transition to personal communication systems (PCSs) is discussed. The evolution of the pan-European digital cordless standards-CT2 and DECT-and industry progress in equipment availability and service implementation are reviewed. The application of cordless access to the domestic market in the United Kingdom and European telepoint, wireless PABXs, and radio drops are described. CT2 product development and availability and cordless data applications are outlined. The migration of microcellular cordless techniques for wider area systems including ETSI's universal mobile telecommunications system (UMTS) and the future public land mobile telecommunications systems (FPLMTS), now under development by CCIR with assistance from CCITT, are also discussed. >

Antenna diversity reception in wireless personal communications

Abstract: An antenna diversity technique for use in wireless personal communications is disclosed. In the so called microcellular phone environment, fading in signal reception is an important consideration. A new way of performing the antenna diversity involves antenna switching during a period of data reception which may results in minimum bit hits to data. The system only requires single receiving part.

Satellite/wireless telephone roaming system with link to network database management system

Abstract: A wireless telephone system capable of servicing a roaming wireless telephone user includes a satellite communications system consisting of at least one orbiting satellite; at least one terrestrial-based gateway having access to a database of users, destination codes (telephone numbers); a network coordinating gateway within a satellite service area; a network control center; and a plurality of terrestrial communications links. The system operates by effecting communication between a terrestrial wireless telephone end user transceiver apparatus and a terrestrial communications link via a single relay through a single satellite or a succession of single relay satellites wherein the relay station may be in motion relative to the end user transceiver apparatus and the terrestrial communications link. The ground-based gateway effects the ultimate decision on linking in cooperation with the network database to effect hand-off from a first orbiting satellite to a second orbiting satellite. The single satellite or preferably a constellation of satellites orbiting near the earth need only translate signals from the gateways to the users and from the users to the gateways without satellite-based control. The gateways are capable of decoding the calls, switching, processing call requests from the end users, processing call requests to the end users, processing call set-ups, handing off of calls to other satellites, and updating databases of users based on information provided by network control and requests from end users.

Internetworking wireless terminals to local area networks via radio bridges

Abstract: The author presents a novel distributed architecture for wireless local area networks (WLANs), where each wireless terminal internetworks with a backbone local area network (LAN) via several radio bridges. The site diversity affords some protections against slow fading and shadowing in the indoor environment. Multiaccess interference from multiple sites sharing the same radio channel is minimized by exploiting the capture effect of spread-spectrum signalling, which also gives additional protections against interference from multipath signals. The internetworking protocol employs a self-learning routing algorithm, which automatically adapts to changes in terminal locations, and prevents multiple copies of each data frame from being forwarded over the backbone LAN. The distributed WLAN architecture eases the management of network topological changes and terminal mobility relative to centralized cellular architectures. >

Power control in packet switched time division duplex direct sequence spread spectrum communications

Abstract: A packet switched time-division duplex direct-sequence spread-spectrum (DS-SS) communication system is proposed for operation in mobile and wireless indoor CDMA communications with Rayleigh fading characteristics. A power control method is then proposed for this system capable of providing effective estimates of the fading state of the channel and using this information to adaptively control the uplink transmission power for equalized received power at the base station. The performance of this power control scheme is evaluated by examining the distribution of the received power compared to a reference level for typical indoor communication system parameters. >

A microcellular interconnection architecture for personal communications networks

Abstract: The current centralized wireless communication architectures are considered inappropriate to cope with the anticipated demand for personal communications. A distributed microcellular architecture is proposed, based on the IEEE 802.6 MAN. Initial traffic estimates indicate that the MAN would provide coverage for an urban area of 8*8 city blocks. It is shown that call control and management functions are dependent upon database distribution and class of handoff. >

Network synchronisation of radio ports in wireless personal communications

Abstract: Time synchronisation of fixed radio ports is crucial in digital wireless personal communications. The Letter describes a centralised approach for providing each synchronisation over the wireline distribution network. Various existing digital transmission facilities are considered as candidates for the wireline transport interface. Issues related to the possible impacts of this approach on evolving distribution network architectures are discussed.

Cordless telephone system for moving conveyances

Abstract: A cordless telephone system serves a building with a moving conveyance such as an elevator. The system has at least one portable cordless telephone, at least one fixed base station that communicates with the portable cordless telephone by a wireless circuit outside the moving conveyance, and a moving-conveyance base station that communicates with the portable cordless telephone by a wireless circuit inside the moving conveyance. A central switch routes calls to the fixed base station or moving-conveyance base station according to the field strength of signals received at these stations from the portable cordless telephone.

The Mobitex packet-switched radio data system

Abstract: This paper is a systems engineering overview of a state-of-art packet switched radio data system-the Mobitex system. RAM Mobile Data operates Mobitex systems in the US and the UK. Mobitex systems are also in operation in Scandinavia and Canada. The system architecture is 'open', which allows any company to enter the wireless data business by providing radio modems and/or application software conforming to the Mobitex interface specification. This paper first outlines the Mobitex network architecture, network protocol, RF system design and the Mobitex 'open' air interface. Finally, the spectral efficiency and response time for transmission of short messages using a wireless packet data network and present day analog cellular systems are compared. It is concluded that a wireless packet data network is superior to analog cellular systems both in terms of spectral efficiency and response time for short data messages. >

Communications requirements of multimedia applications: a preliminary study

Abstract: A preliminary study is presented that provides a framework to explore the communications requirements of wireless applications in general, with emphasis on multimedia applications An estimate of bandwidth requirements for various basic common applications are given, from which network bandwidth requirements in different scenario can be evaluated The delay and error characteristics for certain multimedia applications are described, along with possible implications about the suitability of contention-based and reservation-based MAC protocols The author provides a basis for further investigating the networking requirements as well as the criteria for designing MAC protocols to support multimedia applications in the wireless environment >