Showing papers on "Mobile telephony published in 1989"

Performance analysis of cellular mobile communication systems with dynamic channel assignment

Abstract: The traffic analysis of small-cell mobile networks with dynamic channel assignment is investigated to determine their blocking performance, using a hybrid method of analysis and simulation. The authors particularly focus on the performance problems presented by networks with heterogeneous cell traffic loads, the impact of traffic volatility among the cells, and the impact of multichannel traffic on the channel blocking probabilities. Significant improvement in network performance with dynamic channel assignment is established by numerical results. >

Satellite cellular telephone and data communication system

Abstract: A system for facilitating global cellular/trunked mobile communication is disclosed. This system permits communication with hand held and mobile mounted cellular telephones. The system permits two-way communications anywhere on or above the earth up to a particular height above the earth of several hundred nautical miles. The system employs a number of low-earth orbiting satellites moving about the earth in orbit. Links are provided from the satellites directly to the users and via the public switched telephone network to other users. The satellites are interconnected via links in a ring structure surrounding the earth. Switching is performed by each of the satellites. In addition, each of the satellites hands off a call as it moves out of the range of a particular user.

Mobile communication systems

Abstract: From the Publisher: Presents the fundamental aspects of mobile communications systems. Covers the radio communications channel, its wide-band and narrow-band characterization, and its utilization in mobile and cellular communications systems. Both analogue and digital systems are considered, with emphasis on the latter. Discusses the propagation of signals (including propagation in urban areas), the interference created by the terrain, digital techniques associated with two-way, speech-based communication systems, the TACS cellular system, and digital techniques for high capacity cellular systems. Illustrated.

Remote control system of mobile objects

Abstract: A remote control system for a mobile object, comprising radio beacons each consisting of a master station and some substations, a mobile communication station mounted on each auto-pilot mobile for receiving the radio wave, such as millimetric, from each radio beacon, to let the mobile recognize its own position on the route map, and a control station for transmitting and receiving signals by radio waves to and from the mobile station so as to instruct and correct the moving route of the mobile. Each mobile station is equipped for detecting any corrugations on the route immediately ahead of it, for detecting the ground speed of the mobile, and preferably, for detecting the direction of the mobile so that each mobile station can manage the speed of the mobile object as its master, and can correct and change the route of the mobile on the map by the discriminated signals from these detectors, and the instructions from the control station on the basis of discrimination signals.

Mobile telecommunications system using distributed miniature zones

Abstract: A mobile telecommunications system has multiple base stations (10) each defining a miniature service zone (20) and capable of communicating with mobile stations (16) present in the service zone over a radio link. Geographically associated ones of the base stations (10) are spaced apart from each other by an area in which the mobile stations (16) are not responsive to electromagnetic waves (18) on the radio links, whereby the base stations (10) are allowed to share the same frequency for the electromagnetic waves (18). The base stations (10) are accommodated in an on-road vehicle telecommunications network (22) which switches communications to the base stations (10).

Multi-beam adaptive base-station antennas for cellular land mobile radio systems

Abstract: The authors address the problem of meeting the proliferating demands for mobile telephony within the confinements of the limited radio spectrum allocated to these services. 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 to resolve the angular distribution of the mobile users as seen at the base-station site, and then using this information to direct beams towards the mobiles in both transmit and receive modes. The energy associated with each mobile is thus confined within the addressed volume, greatly reducing the number of co-channel cells. For a given performance criterion, this results in an increase in the spectral efficiency or capacity of the network. The concept is demonstrated using results generated by a computer simulation of a simplified mobile scenario. The realization of a fully adaptive base-station antenna test rig is discussed. >

Experimental fixed and mobile multibeam satellite communications system

Abstract: The authors describe the experimental systems for fixed and mobile satellite communications in the ETS-VI (Engineering Test Satellite VI) program. The objectives of the experiments are space confirmation of the onboard equipment performance necessary for multibeam system implementation and function and performance evaluation of the total system including satellite and earth stations. The multibeam system uses three frequency bands: Ka-band (30/20 GHz), C-band (6/4 GHz), and S-band (2.6/2.5 GHz). A number of new techniques have been applied to enhance the multibeam and satellite switch advantages, including satellite-switch time division multiple access incorporated with demand assigned satellite switch operation, cross-band interconnection associated with cross-band diversity, single-beam/multibeam system interconnection, and band-selective switching. A new multibeam system, called the dynamic channel assigned multibeam satellite system, proposed for the mobile communications system to enhance traffic flexibility, is described. >

Route guidance system for a mobile telecommunication system

Abstract: A mobile telecommunications system includes aplurality of base stations (10) each being communicatable with a mobile station (16) by radio, and a telecommunications network (22) accommodating the plurality of base stations (10) for switching communications to the plurality of base stations (10). A system center (26) is connected to said telecommunications network (22) for selecting an optimum route on the basis of instantaneous traffic conditions. Any of the base stations (10) transmits to the mobile station (16) base station data representative of the base station (10). When the mobile station (16) sends a guidance request for requesting route guidance data, the telecommunications network (22) reports the guidance request to the system center (26). The system center (26) selects, in response to the guidance request, an optimum route matching instantaneous traffic conditions and transmits optimum route data representative of the optimum route to the mobile station (16) over the telecommunications network (22).

Mobile communication control method

Abstract: PURPOSE: To control the size of a radio zone by correcting a reception level from a base station with a correction value of a reception level informed from the base station to a mobile station and informing the threshold level of the reception level required to make communication from each base station to the mobile station. CONSTITUTION: A correction value is informed to a mobile station 4 with an informing signal informed from base stations 1, 2, 3. Moreover, a mobile station 4 reads the correction value with the informing signal from the base stations 1, 2, 3 and measures the reception level 11 of the base stations 1, 2, 3 and obtains the reception level 11 of the base stations 1, 2, 3 and a reception level 12 after the correction to the base stations 1, 2, 3 from the correction value with the calculation. It is regarded by the correction that the radio zones of the base stations 1, 2, 3 are changed automatically. Thus, the size of the zone is controlled by calculating the correction value at the mobile station 4. COPYRIGHT: (C)1991,JPO&Japio

Pan-European cellular radio: or 1991 and all that

Abstract: In 1991 the countries of Western Europe will introduce a new cellular radio system to replace the plethora of different standards currently in place. This initiative provides the European mobile communications industry with a home market of 300 million people, while at the same time giving it a significant technical challenge. This paper discusses the progress towards the standard, outlines the system and describes some of the technical problems now facing the product development teams

High efficiency voice activated CDMA mobile communication system based on master code synchronization

Abstract: The authors propose an innovative code division multiple access (CDMA)-based mobile system for voice (and data) services. The system makes use of voice activation in order to increase the CDMA efficiency (useful transmitted information vs. occupied bandwidth). The synchronization problems are solved by distributing a master code in the forward link and using forced link activation in the return when no speech activity is detected. The blocking probability is minimized by means of multirate speech coding associated with a centralized network control. Bit error rate calculations show all the advantages of operating in a synchronous mode. >

Evolution of NTT high-capacity land mobile communication system

Abstract: The development of a land mobile communication system, MCS-L2 which is Japan's second-generation analog cellular system is presented. The system operates in the 800-MHz band, and service commenced in May 1988 by overlaying it on the first-generation system, MCS-L1, sharing the 15-MHz*2 frequency resources. The field trial results are described. Techniques for increasing the frequency spectrum utilization such as radio zone sectorisation, flexible channel assignment and radio channel interleaving further intended to be applied to MCS-L2 are also discussed. Techniques established by MCS-L2 are basic techniques for digital mobile radio systems. >

Channel switching system for cellular mobile communication

Abstract: PURPOSE:To always communicate with an optimum base station by using the property of TDMA(time division multiple access system) and successively scanning control channel signals of a base station being in service and peripheral base stations by a mobile station to measure reception qualities and selecting an optimum base station. CONSTITUTION:With respect to a mobile station 5, one of n-number of time slots is set to the communication state, and the other time slots are in waiting or stop states. Consequently, the mobile station 5 scans control channels of respective base stations during the waiting or stop state though performing communication. The mobile station 5 uses the intensity of electric field, BER(bit error rate) of data, or the like to measure the reception quality of each control channel and selects the best base station.

A satellite mobile system integrated with the terrestrial cellular network

Abstract: The structure and performance of an integrated system for all mobile communications, based on the Pan European digital cellular network standard, are presented. The system architecture and protocols are discussed. A performance analysis of the satellite access procedure is given. Also, the performance of a satellite system integrated with the terrestrial network is considered, referring to the present bandwidth allocation for a land mobile satellite system. The results suggest that some the proposals are feasible solutions for the integration of a satellite system with the terrestrial network for mobile communications. >

Kingston Adopts the Telephone : The Social Diffusion and Use of the Telephone in Urban Central Canada, 1876 to 1914

Abstract: The adoption and use of the telephone in urban central Canada between 1876 and 1914 are explored within the context of the wider communications environment and the marketing strategies of the Bell Telephone Company. This context becomes the framework for a case study of the social diffusion of the telephone in Kingston, Ont, between 1883 and 1911. Utilizing telephone directories and early city directories, the case study concentrates on the socioeconomic and organizational characteristics of early phone subscribers and the physical location of their phones. Both business and residential subscribers are shown throughout the period to have been drawn mainly from the commercial and prof essional classes in Kingston and to have used the phone mainly for institutional, work-related purposes.

Applications in mobile and satellite systems

Abstract: Mobile communications often require antennas having small size, light weight, low profile and low cost. Microstrip antennas (MSA) are a type of antenna which can meet these requirements, and various MSAs have so far been developed and used for mobile communication systems. The practical applications for mobile systems are in portable or pocket-size equipment and in vehicles. UHF pagers, manpack radars, and car telephones are typical of those. Base stations for mobile communications need antennas with sector radiation patterns. Small, simple antennas are also favoured, since the antenna tower built for the base station can then be smaller and need less support for the weight. In satellite communications, circularly polarised radiation patterns are required and MSAs of either square or circular patches with one or two feeding points can be used for generating the circular polarisation. In this chapter, various types of MSAs which have been developed and applied in mobile and satellite systems are described.

Technological state of the art and future trends of high-speed digital mobile communications

Abstract: The technological state of the art and future trends of high-speed digital mobile communications are discussed. Mobile radio transmission performance for high-speed digital signals is reviewed and specified. The selective fading propagation model, which describes dynamic changes in received signal levels and frequency characteristics, is reviewed, and a novel model is proposed. The characteristics of two-branch diversity and of a decision feedback equalizer employing the Kalman filter algorithm are shown by means of computer simulations. >

High capacity cellular patterns for land mobile radio systems using directional antennas

Abstract: To meet increasing demand for mobile communications with a fixed spectrum and at reasonable cost, directional antennas have been used in cellular mobile radio systems. This paper reviews sectorised patterns that have been proposed so far, and then describes how to achieve high capacity systems by taking a new approach to the design of cellular patterns. Some novel patterns, with less than or equal to two hexagons per cluster are described. Performances are assessed in terms of the first decile carrier-to-cochannel interference (C/Ic) and traffic density for a given blocking probability. Cell site efficiency is also considered.

Tdma mobile communication system for decentralized base station

Abstract: PURPOSE:To improve the frequency availability and to decrease the number of receivers of the base stations by calling selectively the mobile stations within the zones of plural decentralized base stations via a TDM type signal transmission means and at the same time securing a channel constitution. CONSTITUTION:A calling area 2 of a calling station 1 includes the zones 4 of plural decentralized base stations 3 and these calling and base stations are connected to a mobile communication exchange station 6. At the same time, a subscriber file control home memory 7 for registration of positions, etc., is set at a specific station 6 and each station 6 performs an access to the memory 7 via a common line (a). The station 1 has a calling channel 11 and a frame pattern F1 of a frame synchronizing signal 12 differs for each calling station. For the message channels, a down-channel 28 led to the mobile station from the base station applies a TDM transmission form and an up-channel 26 to the base station from the mobile station applies a TDMA transmission form respectively.

Supervision and control in cellular systems

Abstract: The necessity for a novel cellular supervision and control system is described from two points of view. The first view is that increasing service complexity and customer demands are forcing the creation of a supervision and control system that will apply a common database and a unified approach to network management. The other point of view is that a supervision and control system should have improved automatic and remote functions, and should provide the operator with simplified interfaces. The system function structure, which is hierarchical, will permit extensive and sophisticated cellular network operations to effect the required total network operations. The appropriate design objectives are described, and methods for their implementations are discussed. >

A new mobile subscriber set for high-capacity land mobile communication system

Abstract: The authors describe the design concept, configuration, and characteristics of a new mobile subscriber set (MSS) for NTT's new high-capacity land mobile communication system. In spite of many complicated features, such as diversity reception, cochannel interference detection, automatic frequency control, and system compatibility, the new MSS has been made smaller than the conventional MSS through common use of radio portions and software modules in addition to redevelopment of LSIs. The standby and transmitting time of the MSS in battery operation was drastically improved as against the conventional MSS by thorough reduction of component current drain and application of intermittent reception. The sets have worked well in Tokyo's high-capacity system (MCS-L2) and over the whole area of Japan (MCS-L1). >

A simulation package for digital cellular mobile radio applications

Abstract: A simulation package has been developed for predicting the response of a cellular mobile radio channel to the transmission of narrow pulses. Four types of urban areas, ranging from dense urban to suburban, and three RF frequencies in the 0.5 to 3 GHz range are considered. These areas are geometrically modeled by a cellular pattern of hexagons, making the model compatible with existing digital cellular mobile communication plans. The simulation model is wideband in nature, but it can also be used to predict the performance of narrowband systems. The preliminary results with the simulation package are promising. >

Performance analysis of mobile packet radio networks

Abstract: A model is proposed for analyzing the performance of a mobile packet radio network. In this network, a node is allowed to move around with a random velocity. Hence, the distribution of the number of nodes in one's transmission circle is dependent on the mobility of the nodes. A queuing model is developed to evaluate this distribution and the effects of node mobility on system performance. This effect cannot be obtained by classical two-dimensional Poisson model. It is found that an optimal power radius is dependent on the node mobility. >

Inmarsat Second Generation Satellites for Maritime Communications

Abstract: The second generation satellites of INMARSAT (International Maritime Satellite Organization) are in the final stage of integration and testing. The satellites will satisfy the needs originated by the rapid expaneion of the system and will allow the introduction of new mobile communications services. This paper gives a short description of the INMARSAT network and outlines the essentials of the spacecraft design and the types of services that will be provided using the new satellites; in particular it will consider the characteristics of the communications transponder, its design and technology, the requirements and the design solutions and the most significant communications parameters.

Prospects for a common air interface for cellular and cordless systems

Abstract: Market forces will eventually force cellular and cordless systems to converge into one integrated network having the virtues of both cellular and cordless systems. The eventual universal mobile telecommunication system (UMTS) would be a federation of systems with a common but flexible air interface. The authors compare the air interface functions of cellular and cordless systems. The GSM and DECT air interface implementations are taken as examples of cellular and cordless air interfaces respectively. They identify those functions which can have common solutions and those which require dual solutions for the two modes. This work was undertaken as part of the RACE mobile project. They also mention some of the techniques being investigated.

Evaluation of Mobile Telecommunication Systems

Abstract: Mobile telephony exhibits transmission characteristics and user-interface features distinct from traditional telephony. To study these differences in systems designed for use in commercial airplanes, trains, and automobiles, we used a variety of techniques, including both laboratory and field observations. We found that mobile telephony, viewed from the user's perspective, is quite different from traditional telephone service. In the present paper, we review the assessment techniques that we employed, and consider their strengths and weaknesses for characterizing the performance of mobile telecommunication systems. Our results indicate that there are five major sources of potential user-interface problems in mobile telephony: (1) use of credit cards; (2) system delays; (3) lack of coordination among multiple sources of feedback; (4) the mechanism for completing multiple calls without credit-card reentry; (5) voice dialing. Because solving the problems we have identified does not require new or overly expe...

VSAT-an alternative communication network for fixed and mobile applications

Abstract: The new generation of VSAT networks now offer personalised communication facilities from VSAT to hub or VSAT to VSAT which have hither been reserved for much larger earth stations. The new VSAT is therefore a viable competitor, for an alternative network, in parts of the world where a reliable line infrastructure does not exist, or for small private business networks or mobile/defence networks. By the more efficient use of bandwidth new technology has reduced the hub and satellite costs. Small VSAT networks are now commercially viable whilst retaining the expansion facilities to that of large networks. >