Showing papers on "Mobile telephony published in 1990"

Analysis for mean effective gain of mobile antennas in land mobile radio environments

Abstract: A method is described for analyzing the mean effective gain (MEG) of antennas moving in a mobile communication environment. The MEG characteristics of a mobile antenna are determined by the mutual relation between the antenna patterns and the statistical distribution of incident waves in an environment. To analyze this relation theoretically, a general expression for the MEG using a statistical model of incident waves is derived, and a novel statistical model, whose distribution is uniform in azimuth and Gaussian in elevation, is proposed. The validity of the statistical model is confirmed through 900-MHz-band measurements carried out in a Tokyo urban area, and the empirical parameters for the statistical distribution are described. The MEG characteristics of a half-wavelength dipole antenna are investigated using the proposed method, and it is shown that the theoretical curves calculated using the empirical parameters are in excellent agreement with experimental results. This analysis is extremely applicable for evaluating the MEG characteristics of arbitrary mobile antennas in various mobile communication environments. >

The performance enhancement of multibeam adaptive base-station antennas for cellular land mobile radio systems

Abstract: The problem of meeting the proliferating demands for mobile telephony within the confinement of the limited radio spectrum allocated to these services is addressed. A multiple-beam adaptive base-station antenna is proposed as a major system component in an attempt to solve this problem. The approach is demonstrated by employing an antenna array capable of resolving the angular distribution of the mobile users as seen at the base-station site, and then using this information to direct beams toward either lone mobiles, or groupings of mobiles, for both transmit and receive modes of operation. The energy associated with each mobile is thus confined within the addressed volume, greatly reducing the amount of cochannel interference experienced from and by neighboring cochannel cells. To ascertain the benefits of such an antenna, the conventional and proposed antenna systems are modeled in a typical mobile radio environment. For a given performance criterion, the theoretical results indicate that a significant increase in the spectral efficiency, or capacity, of the network is obtainable with the proposed antenna. >

Increased capacity using CDMA for mobile satellite communication

Abstract: The performance of a spread-spectrum CDMA (code-division multiple access) system in a mobile satellite environment is analyzed. Comparisons to single-channel-per-carrier FDMA systems are presented which show that the CDMA approach provides greater capacity. Results from computer simulations, laboratory tests, and field tests of a prototype modem are also presented. The tests results show excellent performance of the modem in the mobile environment and also the feasibility of the spread-spectrum approach to satellite mobile communications. >

'Fibre/radio' for the provision of cordless/mobile telephony services in the access network

Abstract: A four channel CT2 fibre/radio system has been demonstrated over singlemode fibre using subcarrier multiplexing techniques. A spurious free electrical dynamic range of 51 dB was achieved which is sufficient for a mobile range of approximately 100 m. The use of subcarrier multiplexing simplifies the design of the radio transceiver and allows complex processing equipment to be located at the local exchange.

Mobile communications system

Abstract: A system for mobile communication includes a number of base stations 10, 13, 16, 20, 23, 26 with users 30, 31, 45 and 46. Associated with each base station is an interface unit 10a, 13a, 16a, 20a, 23a and 26a which packetises voice information and includes header information concerning user and destination addresses. These interface units tracks the movement of the various user by passing control blocks from interface unit to interface unit. Packets are routed via routing block 40 or 41 and switches 50-52. The stored information within the base station interfaces allows movement from one base station to allow to be handled without call loss.

Interface between mobile telecommunication stations and trunks that link to communication carriers

Abstract: An interface between mobile telecommunication stations and trunks that link with communication carriers of various media comprises station channels (11, 12, 13, and 14) that connect to telecommunication stations, trunk channels (1, 2, 3, and 4,) that connect to trunks that link to communication carriers, software code executable for interrogating the trunk channels for availability, software code executable for determining the communication medium or network of least cost, and software code executable for routing the telephone call from one of the station channels to the available trunk channel linked to the communication carrier having the medium or network of least cost. If the routing is to a trunk line linked to satellite communications, the interface selects the coast earth station of least cost based upon the location of the ocean going vessel, the destination of the call, and other rate considerations. Call progress through the interface is supervised such that the call is terminated after an extended period of ring no answer, busy, dead air, etc. The invention also provides for automatic leveling and creates a detailed call record of all calls originating from the ship for billing purposes.

Control strategy for reuse system assignments and handoff

Abstract: Disclosed is a method of selecting a relatively high reliability signal path between a mobile communication unit and a number of possible base sites.

Method of arranging radio control channels in mobile communications

Abstract: According to a method of arranging radio control channels in mobile communications, for covering a service area with a plurality of radio zones and causing base and mobile stations to exchange signals through the control channels, a broadcasting information transmission portion is assigned to the control channels. This broadcasting information is to be transmitted from the base station to each mobile station to broadcast information associated with radio zones. Information associated with control channel structure in units of base stations is broadcast to the broadcasting information transmission portion. A frequency and a time slot capable of causing the base station and the each mobile station to exchange the signals are determined on the basis of the pieces of broadcasting information and an identical number commonly recognized by the base and mobile stations.

The OmniTRACS/sup R/ Mobile Satellite Communications and Positioning System

Abstract: The OmniTRACS two-way mobile satellite communications and position reporting system is described. This system provides message communications between moving vehicles and their operations centers. Me mobile unit directly communicates with a central hub facility which provides system control, message processing and archival, and point-to-point communications with the operations centers. QASPR, a dual satellite positioning system giving accuracies in the United States to about 1/4 mile, is described. Experiences and benefits to the trucking industry are also highlighted.

Traffic capacity of cellular mobile communications systems

Abstract: In a cellular mobile communication system, the traffic capacity of the system is an important quantity, and depends on the way that channels are allocated to calls. Many channel allocation algorithms have been proposed, and this paper makes a direct comparison of some of them. Specifically, the operating regimes considered are fixed channel assignment, dynamic channel assignment, directed retry, and directed handoff. The main conclusion is that directed handoff gives a strong gain in traffic capacity and traffic adaptability for these systems. The paper also discusses some of the factors affecting the future development of mobile communication systems.

Land mobile satellite systems

Abstract: The general advantages and potential operating characteristics of the mobile satellite service (MSS) are described, and distinctions are made between radio telephone, which is interconnected to the public switched telephone network, and private mobile radio systems. Mobile satellite service offers voice, data, position location, and paging services, interconnection to the public switched telephone network, and the possibility of private networks. Performance and cost characteristics are given along with summaries of market needs and market demands. The space and ground systems of the MSS are described. >

Mobile communication control system

Abstract: PURPOSE: To improve the transmission incomplete rate by allowing a mobile station to access with a minimum transmission output noticed in advance at calling at first and to access with a transmission output increased stepwise up to a maximum transmission output when the communication of a control signal with a radio base station is unsuccessful. CONSTITUTION: A mobile equipment 3 receives information of a frequency of a communication control channel used in a radio zone 1 where the mobile equipment 3 is resident, a maximum and a minimum transmission output, a change in the transmission output for each retransmission and number of times of retransmission through an incoming control channel. The mobile equipment 3 is provided with a transmission power control section 9 and sends a signal with a minimum transmission output based on the noticed information at calling. In this case, when the communication of the control signal with a radio base station 2 is unsuccessful, the mobile equipment 3 accesses the radio base station while increasing the transmission output sequentially stepwise up to the maximum transmission output. COPYRIGHT: (C)1991,JPO&Japio

Digital cellular mobile‐radio system ECR900

Abstract: In Europe, second generation equipment for mobile telecommunications will operate in the WMHz band as defined by the Groupe Special Mobile (GSM) of the European Conference of Posts and Telecommunications (CEPT). By contributing to and complying with these recommendations, Alcatel, in cooperation with Nokia and AEG, has contributed in developing a pan-European digital Cellular mobile-Radio system, the ECR900. This system is based on the Intelligent Network (IN) concept. The Alcatel E10 and the System 12 digital switches are compatible IN components and naturally accommodate the ECR900 system. Outside these digital exchanges, specific mobile functions are concentrated at mobile-radio service control points, built on ALCATEL8300 telecommunication processors. The ECR900 system has already been ordered in France for the GSM Mobile-Radio network, in the Federal Republic of Germany and in the Netherlands.

Basic performance of a direct conversion DECT receiver

Abstract: The measured operating performance of a new incoherent direct-conversion receiver for high-data-rate mobile communication systems is presented. The results prove the suitability of such a receiver for the future digital European cordless telecommunication (DECT) standard.

Mobile telecommunication terminal

Abstract: A mobile telecommunication terminal, for example a hand-held mobile telephone which contains a hand-operated dynamo as power supply. This makes the device independent of batteries or, after failure of the battery, an emergency operation can be maintained. The hand-operated dynamo is preferably driven by means of a toothed rod which is moved via an operating lever protruding from the side wall of the device.

Performance of a decision feedback equalizer under frequency-selective fading in land mobile communications

Abstract: Some means to cope with frequency-selective fading is indispensable to the realization of a wideband digital mobile communication, and various investigations have been made to this end. For example, the decision feedback equalizer (DFE) is considered promising, since it requires smaller-scale equipment and is versatile in applications. The application of DFE to mobile communication requires tracking to the time-varying channel as well as the fast initial adaptation. Thus, comprehensive investigations, including the construction of the equalizer and tap-updating algorithm are needed. The Kalman algorithm is employed as the tap-updating algorithm. By introducing the memory factor into the algorithm, the tracking performance to the time-varying channel is improved as well as the speed of the initial adaptation. A computer simulation is made for the proposed method based on the model of 256 kbit/s TDMA system with QPSK modulation. It is verified that DFE is useful in compensating for the frequency-selective fading in mobile communication.

A satellite-based personal communication system for the 21st century

Abstract: Interest in personal communications (PCOMM) has been stimulated by recent developments in satellite and terrestrial mobile communications. A personal access satellite system (PASS) concept was developed at the Jet Propulsion Laboratory (JPL) which has many attractive user features, including service diversity and a handheld terminal. Significant technical challenges addressed in formulating the PASS space and ground segments are discussed. PASS system concept and basic design features, high risk enabling technologies, an optimized multiple access scheme, alternative antenna coverage concepts, the use of non-geostationary orbits, user terminal radiation constraints, and user terminal frequency reference are covered.

Connection control method in mobile communication

Abstract: PURPOSE: To attain the control ensuring only a minimum communication means even when a normal incoming call is rejected by sending a required notice such as the presence of an incoming call from a base station and a telephone number of a caller to a mobile equipment when an incoming call reject signal is sent from the mobile equipment with respect to the transmission of the incoming call signal to the mobile equipment. CONSTITUTION: When a mobile subscriber depresses an incoming call reject button of a mobile equipment 10, the mobile equipment 10 turns to an incoming call reject state. The mobile equipment 10 sends an incoming reject signal to an incoming call signal from a base station 4 in this state. The base station 4 receiving the reject signal informs one of sets information such as presence of a call, a telephone number of caller, message from the caller and storage of the message at the base station to the mobile equipment 10, the mobile equipment 10 sends a reply signal to the base station 4 and displays the content of reception or the like. Thus, minimum circuit is ensured while a usual incoming call is rejected. COPYRIGHT: (C)1992,JPO&Japio

Experimental digital cellular system for microcellular handoff

Abstract: An experimental digital cellular system composed of a private branch exchange (PBX)-based MSC (mobile switching center), three base stations, two mobile stations, and a radio channel simulator, is developed. The system uses a mobile originated handoff process; i.e. a mobile station requests a handoff to the MSC based on signal strength from surrounding base stations. All control channels are multiplexed on the same carrier so that mobile stations can monitor signal strength quickly. Experimental results show that a handoff decision can be made within a second, even under slow fading (such as walking speed), which agrees with the theoretical calculation very well. It is shown that the whole handoff procedure works reliably under a typical microcell propagation condition. >

State information panel for inter-processor communication in an autonomous mobile robot controller-a proposal of the system architecture for autonomous mobile robot

Abstract: The controller architecture for an autonomous mobile robot is considered. First, the controller is divided into a behavior level and a functional level. The interface of these levels are discussed and the conceptual architecture for the autonomous robot are proposed. The special feature of this architecture are 'functional distribution' and 'centralized decision-making'. The multi-processor architecture for realization is also proposed. >

A new millimetre wave satellite system for land mobile communications

Abstract: Cellular systems are gaining wide acceptance. In Europe the GSM system is expected to provide service to more than 10 million users by the year 2000. Assuming that a demand for additional services at 64 kbit/s or so will not easily be satisfied either by the present GSM system or by advanced satellite systems at L-band, this paper proposes a new satellite system at EHF (40150 GHz) to be integrated at the end of the decade with the GSM system or its descendants. First, the paper describes the main obstacles for the new system, in terms of channel characteristics and technology developments, and then illustrates a preliminary system design to show the technical feasibility in the proposed ten years time scale.

Intelligent networking for digital cellular systems and the wireless world

Abstract: Current trends in wireless and networking technologies are reviewed, and the benefits and potentials that can result from intelligent networks and services incorporating both technology trends are addressed. The transition from analog to digital cellular transmission in public systems to support increased subscriber densities and provide enhanced services, the low-powered microcellular systems which will provide flexible services within buildings. and intelligent wireless networks that will enhance the mobility of both corporate and residential subscribers are discussed. >

Authentication method in digital mobile communication

Abstract: PURPOSE:To enable a mobile station to be shared and to prevent illegal use by specifying a authentication confirmation signal and a authentication reply signal of a mobile set and a subscriber with a random number and a secret key and starting the operation when both the signals are coincident. CONSTITUTION:A random number generating circuit 31 generates at first a random number R for an authentication request in a base station and transmits the number to a mobile station. A mobile set 30 enters the random number R and secret keys Ks, Kp of the mobile set and subscriber to a signal conversion circuit 33 to obtain an authentication reply and a communication ciphering key Ke1 and transmits the authentication reply to the base station. The base station inputs the random number R and secret keys Ks, Kp to a signal conversion circuit 32 to obtain an authentication reply and a communication ciphering key Ke2. A comparator circuit 34 compares a bit pattern of the authentication reply received from the mobile station with a bit pattern of the authentication reply generated in the base station, and enables the authentication of the mobile set when they are coincident and disables the recognition in other cases. That is, then the authentication of the mobile set and the subscriber authentication are implemented simultaneously by one authentication procedure to share the mobile station by plural subscribers without degradation in the throughput.

Land mobile communications in Ku-band - Results of a test campaign on Eutelsat I-F1

Abstract: This paper presents and discusses the results of technical tests on land mobile communications conducted in June and July 1989 in Europe using a EUTELSAT satellite. The land mobile communication system under test was that already operated by QUALCOMM in the U.S.A. under the registered name OmniTRACS. The field trial was organized in conjunction with the Signatories who expressed to EUTELSAT an interest in a full-scale technical investigation of the system. The aim of the field trial was to evaluate the technical characteristics of the system and test its performance in different operating conditions. The results establish the relationship between transmission performance (i.e. essentially the required number of transmission attempts in order to get a message through the communication channel), and the environment of the land mobile, the satellite transponder's mode of operations and the interference conditions.

The ISDN approach for mobile radio

Abstract: This paper describes the Pan-European digital mobile communication system, defined by GSM, which is called in the following the 'GSM-System, its basic characteristis and its influence on the implementation strategy. The first part deals with the basic characteristics of the GSM-System, its system elements and the interworking between these elements. Network scenarios explain the overall message flow through the system. The second part highlights strategies for the implementation of system elements. It describes the requirements to be fulfilled by elements like Base Station, Mobile Services Switching Center Visitor and Home Location Register, Authentication Center and Operation and Maintenance Center. The third part deals with strategies for the mobile com munication network architecture and associated network topologies. The questions of overlay network and integration of the GSM-System into the ISDN are treated, as well as the associated interfacing strategies. The fourth part explaines in more detail basic implementation strategiesfor various system elements. Special emphasis is put on how an JSDN exchange will be expanded to provide the additional GSM functionality of a Mobile Services Switching Center (MSC). It will be demonstrated how the Visitor Location Register (VLR) and Equipment Identity Register (EIR) databases may be integrated in the ISDN exchange.

Automatic pursuit routing for mobile communications network

Abstract: This paper describes an automatic pursuit routing capability necessary for a public land mobile network because mobile stations move freely through service areas. The purpose of pursuit routing is to automatically deliver calls to the called mobile station through the best route. Callers can dial without knowing the actual location of the called mobile station. Automatic pursuit routing requires three logical functions of the mobile communication control center (MCC): the gateway MCC, the home MCC, and the visited MCC. The charging method, numbering plan, and the signaling architecture for implementation are also described, and the effects of the APR and the MCC logical function capabilities are discussed.

Mobile communication line control system

Abstract: PURPOSE:To prevent service from dropped by providing a mobile exchange with a table for determining a radio zone to be used in accordance with the average moving speed of a mobile terminal, and when the mobile terminal moves so as to cross the radio zone during the period of communication, determining the ratio zone used by the table. CONSTITUTION:One area is covered with small zones 300 to 320 controlled by radio base stations 400 to 420 and large zones 330, 340 controlled by radio base stations 430, 440 and the moving speed of the mobile terminal 700 is found out by monitoring a speedmeter or a fading pitch so that the radio zone to be used can be determined by the system in accordance with the moving speed. When the mobile terminal 700 is moved during the period of communication, the radio zone to be used on the moved destination is determined from the table for determining radio zones existing around the terminal 700 and the radio zone to be used in accordance with the average moving speed. Consequently, channel switching processing due to the movement in the radio zone during the communication can be reduced and service can be improved.

Mobile communication incoming call control system

Abstract: PURPOSE: To present the mobile communication incoming call control system to automatically control an incoming call by a mobile equipment even when a callee does not operate the mobile equipment in the operational condition of disabling an incoming responding operation and to hold a response in the condition of disabling the incoming call response. CONSTITUTION: The result of detecting the operational condition by an operational condition detecting means 15 is inputted to a mobile station 10. At the mobile station 10, an incoming call response judging means 16 judges whether the incoming call response is enabled or not. When the incoming call response is disabled at the mobile station 10, an incoming call response holding signal transmitting means 17 transmits a signal to a radio base station 11 so as to hold communication. When an incoming call response holding signal 18 is received, the radio base station 11 holds the following communication by a communication holding means 19. These means are automatically controlled without depending on the callee. COPYRIGHT: (C)1992,JPO&Japio

Mobile communications equipment

Abstract: Mobile telecommunications equipment comprising a vehicle mounted mobile base unit (2) and a number of portable units (1) which may comprise portable telephones. The first and second units (2) are interconnected by a communication link (4), the units including a microprocessor (8) which senses characteristics of the communication link (4), the equipment further including feedback and control means (5, 8) for adaptive control of the link in accordance with the communications environment.