Showing papers on "Mobile telephony published in 1985"

A comparison of prediction methods for 800 MHz mobile radio propagation

Abstract: The design and installation of a mobile radio system involves the evaluation or prediction of the propagation characteristics associated with the geographical area of interest. A wide variety of prediction techniques has been developed for different mobile environments, so that the task of selecting an appropriate propagation prediction method can be difficult and complex. This is especially true for systems operating in the upper-UHF band of 800-950 MHz, where mobile radio services are rapidly growing. A practical comparison is given of current prediction techniques available in the literature (for slow lognormal fading rather than multipath Rayleigh fading), with an emphasis on three essential criteria to consider in the selection process: the type of terrain or geography covered by each method, the form of prediction provided (e.g., transmission loss estimates, field strength contour maps, etc.), and the implementation difficulty and degree of sophistication.

Optimal design for cellular mobile systems

Abstract: Cellular zone design parameters for a land mobile communication system are clarified. System parameters having a strong influence on cellular system performance are discussed and some problems encountered when system parameters are changed are examined.

Satellites and mobile phones: Planning a marriage: Dramatic improvements in rural communications may be in the offing as direct service by satellite to mobile phones moves closer to reality

Abstract: It is pointed out that cellular radio is not well suited for rural areas, where potential users are sparsely distributed. Mobile satellite service is seen as the ideal way to pick up where cellular leaves off, particularly if mobile units are developed that will work with either system. The new system could also provide nationwide two-way voice dispatch services. Interest in the new system is high in rural areas because the divestiture of the American Telephone & Telegraph Co. and the deregulation of the telephone industry are making local telephone service more expensive for rural subscribers. Of particular concern is the high cost of the rural local loop, the cable pair that connects the subscriber to an exchange. Mobile telephone service could replace the expensive local loop by connecting the rural telephone user directly to a large exchange, perhaps far away. A general description of a mobile satellite service is provided. Attention is also given to the regulatory change being considered by the US Federal Communication Commission.

A New Propagation Path-Loss Prediction Model for Military Mobile Access

Abstract: The Longley-Rice propagation path-loss prediction model,1,2 developed by the National Telecommunications and Information Administration (NTIA) mainly for troposcatter transmission and long-range line-of-sight transmission, has often been suitable for ground mobile radio propagation by adding an adjustment factor for urban areas. Since the model was not originally developed for a mobile radio environment, it does not provide a desired mean value which should match experimental values to a standard deviation of 8 dB. Okumura's model,3 obtained from empirical data gathered in the Tokyo area, has been used for commercial mobile radio because this model was designed specifically for the mobile radio environment. Although it is not a proper model for predicting the propagation path-loss in the United States, most measured values are within 8 dB of the mean predicted value. This paper introduces a model which predicts the actual measured value is within a standard deviation of 3 dB instead of 8 dB from the predicted value. A more accurate prediction of path loss can enhance a military system's performance. In the military environment set of base station sites must be properly chosen to allow optimum connectivity for tactical mobile radio communications. This model provides such information. Each time the base station is removed to a new site, this model can be used to select a new optimum site based upon the battlefield condition.

Mobile message communication system

Abstract: PURPOSE: To make it possible to use a rotary dial or push-button telephone set as a message terminal in the fixed side by converting information inputted with a code to a voice by a medium converter in a message terminal in the mobile station side to output this voice to a telephone terminal in another mobile station or the fixed station and performing the reverse operation. CONSTITUTION: A message transmitted from a message terminal 1 by packet multiplexing reaches a radio base station directly or through a communication satellite 2 and is subjected to transmission and reception control and protocol conversion and is inputted to a mobile communication exchange 4 through a line of contacts 13 or a control line. The packet multiplexed signal is demultiplexed individually and is sent to a general network 5 through a line 15 and is inputted to a medium converter 7 from the general network through a communication processing exchange 6. The code signal of the message inputted to the medium converter is converted to a synthesized voice and is sent to a telephone terminal 9 from the communication processing exchange 6 through the general network 5. The message sent from then telephone terminal 9 with a voice is converted to a code signal and is sent to the message terminal. COPYRIGHT: (C)1987,JPO&Japio

Terrestrial Mobile Communications - Cellular, Satellite and Their Interfaces

Abstract: A general description of both cellular and satellite communication systems for mobile terrestrial communications is given. The current state of development and use of these systems is given, together with predictions for expansion of the networks into new markets, such as an extension of the public telephone service to aircraft. Particular emphasis is placed on the role of new microwave technology, both in regard to the future for GaAs monolithic circuits and to prospects for the use of higher frequencies in the mm-wave band. Examples of systems and technology from both civil and military applications are used to illustrate the importance of mobile communications in the exploitation of advanced technology.

AUTOPLEX TM cellular telecommunications system description and deploymnet

Abstract: The AUTOPLEXTM Cellular Telecommunications System is the first commercially available product family which supports the state-of-the-art, AT& T-Bell Laboratories developed cellular mobile radio telecommunications technology. This paper describes the system's functional components, features and operation. Also discussed are system deployment issues including future growth capabilities.

System integration of land, maritime, aeronautical mobile telephone services

Abstract: This paper describes the design concept for system integration of automobile, maritime and aeronautical telephone services presently under development at NTT. The background, current status and system outline of the public mobile telephone services provided by NTT are described first. The future plans for automobile, maritime and aeronautical mobile telephone services are then described. Finally, it is shown that new systems for coastal maritime and aeronautical telephone services can be realized economically and quickly by integrating them into an automobile telephone system.

Mobile communication paging system

Abstract: PURPOSE:To attain efficient calling of a mobile radio station by transmitting a power supply throw-in command and a power supply disconnection command of the mobile radio station to a radio base station and storing them in its storage section so as not to call the mobile radio station whose power is disconnected. CONSTITUTION:When an engine key 16 is turned off while a transmitter-receiver 12 is in operating state, it is informed to a controller 15, which transits a code representing the power supply disconnecting state and a mobile radio station number to a radio base station 18 from the transmittor-receiver 12. After a response signal representing that the radio base station 18 receives the said signal is received, a power switch 13 is turned off to interrupt the power to the transmitter-receiver 12. The power supply application and disconnection state are stored at each mobile radio station by a storage section 22 of the radio base station 18. When a call request to a movile radio station is incoming, the radio base station 18 reads the storage section 22 so as to check the state of power of each mobile radio station and does not conduct calling processing to a mobile radio station whose power is disconnected.

Private voice and data considerations for the AUTOPLEX cellular systems

Abstract: The frequency spectrum in the 850 MHz range which has been made available by the FCC in 1981 to support cellular telecommunications has given carriers the opportunity to provide new communication services to the mobile public. Concurrent with this opportunity is a growing awareness of the need to protect cellular services against eavesdropping. Business and professional cellular system users will require confidential communication with offices and clients, and will therefore need the assurance of privacy in these transactions in order for the service to satisfy their needs. Similarly, the operations of industry, government, and the general public are expanding needs for access to data resources via the cellular radio network. Solving the problem of providing private voice and data services over the cellular radio channel in a way that satisfies the Compatibility Standards associated with the FCC's 1981 Final Report and Order has led to an array of issues relating to the design of the service architecture and to the selection of performance requirements for the signal processing algorithms. This paper addresses these issues.

Mobile telephone system and non-wire line network

Abstract: The need to communicate with non-fixed points without the use of wires led to the development of mobile telephone systems in the early 1920's. Since then, the expanding need for mobile phone service and resulting growth have led to the development of the Advanced Mobile Phone Service (AMPS) by the Bell System. This thesis describes the AMPS system and explains how service is provided to mobile units roaming in a typical area of up to 25 square miles. A network is proposed to interconnect service areas to expand the coverage to a much larger geographic area. Efficient use is made of the limited bandwidth available for network communication. The network is able to manage mobile units that move from one service area to another during a call, and can efficiently locate mobile units throughout the network area.