Radio Telephone Service Research Articles

ANALYSIS OF THE GENERAL QUALITY INDICATORS OF THE PROVISION MOBILE RADIOTELEPHONE COMMUNICATION OPERATORS OF THE VOLGA FEDERAL DISTRICT

The article presents the results of the analysis of the general quality indicators of the mobile radiotelephone services. The source of data for such analysis was the results of tests organized by Roskomnadzor in the period from 2022 to 2023 on the networks of four major mobile operators (Beeline, Megafon, MTS and Tele2) in the five largest cities of the Volga Federal District with a population of more than a million inhabitants. The main quality indicators have been selected: voice transmission, data transmission and SMS transmission, for which a comparative analysis is performed based on a rating methodology. The positions of the control objects (the city center of the region and the operators of the PRS) are distributed in accordance with the value of the same type of indicators for each control parameter with the determination of the best and worst objects. A cumulative final rating has been compiled for each city where inspections were carried out and for each operator.

Demand assignment multiple access and dynamic channel allocation strategies for integrating radio dispatch and telephone services over mobile satellite systems

The authors discuss the performance analyses of a novel demand assignment multiple access (DAMA) scheme addressing the special characteristics of the mobile radio service (MRS), and a new method for dynamically allocating a common pool of channels to both MRS and mobile telephone service (MTS) to improve channel utilization. The new DAMA scheme makes use of call queuing, batch processing, and pipelined signaling to minimize call setup overhead for MRS traffic. MRS call setup delays were analyzed by simulation modeling of a mobile satellite system (MSS) with many mobile voice-dispatch networks operating over a multiple spot beam satellite to investigate the effects of traffic volume, batch size, and batch service disciplines. A reserved channel margin algorithm for dynamic channel allocation was shown to be effective in harmonizing the different call setup performance requirements for MTS and MRS. Numerical results show that dynamic channel allocation applied to a common pool of 40 channels enables a 20-25% increase in the number of mobile terminals compared with a fixed allocation of 20 channels to each of the two services. >

Traffic performance characterisation of a personal radiocommunication system

A recently proposed personal radiocommunication system is described. The system, which is intended to provide a low-cost mobile radiotelephone service, employs a novel radio link architecture that combines features of centralised and distributed control. Consumers would typically purchase two transceivers, one for a vehicle, the other for the home. The latter unit interfaces with the public switched telephone network through an ordinary modular coupling. Two types of payload radio channels are used, local direct and repeater. Users gain access to these channels by successfully completing a specified exchange of command messages on supervisory channels used in a random access mode. An analytical model was developed to characterise traffic performance and a simulation of the proposed system's traffic characteristics was undertaken. Both are described in the paper. Predicted performance characteristics are presented.

Satellite augmentation of cellular type mobile radio telephone systems

NASA's ATS-6 satellite relayed voice bandwidth communications between five trucks and the trucking company dispatchers as the trucks traveled throughout the north-eastern quarter of the contiguous United States. The experiment, conducted over a seven month period, demonstrated that propagation characteristics are much different for the satellite-mobile links than for terrestrial-mobile links. A properly designed satellite system can provide high quality, reliable voice and data communications except where the vehicle-satellite path is shadowed by a structure or terrain feature. Mobile equipment in the experiment was adapted from commercial mobile radios. The vehicle antennas were 75 cm tall, 2 cm diam. Another experiment proved the feasibility of vehicle position surveillance using active two-way tone-code ranging through ATS-6 to provide one line of position and passive one-way ranging by measuring the time-of-arrival of a signal from an independent satellite. A position fix was printed out at an earth station 1 sec after it sent the interrogation signal to the distant vehicle, a towboat on the Mississippi River. The line of position from ATS-6 was accurate to 0.1 nautical mile using a voice bandwidth ranging signal. The line of position from the NOAA GOES satellite was accurate to 2 miles, using 100 Hz signal bandwidth. If the signal from the independent satellite had the same bandwidth and signal-to-noise ratio as ATS-6, the fixes would have been accurate to about 0.1 nautical mile. A concept study concluded that satellites might be a cost effective augmentation of terrestrial cellular type mobile radio telephone systems. The satellites would serve thinly populated areas where terrestrial systems are not cost effective. In the United States, the satellites would serve about 90% of the land area where 20% of the population resides. A multibeam satellite with many channels in each beam would be compatible with the urban terrestrial systems and together they would provide a nearly ubiquitous mobile radio telephone service.

The concept of an integrated terrestrial/land mobile satellite system

Potential satellite markets in the public safety (disaster relief, emergency medical, and law enforcement) and common carrier (mobile radio telephone) service areas are identified. The public mobile telephone segment is then examined to illustrate a methodology for identifying a potential satellite addressable market, including capacity requirements for roughly sizing a satellite. It is postulated that satellites could serve this lower density (mobiles per square kilometer), thin-route market at a competitive cost and thus complement terrestrial systems in the urban and more densely populated areas to provide an integrated nationwide mobile service.

GMSK Modulation for Digital Mobile Radio Telephony

This paper is concerned with digital modulation for future mobile radio telephone services. First, the specific requirements on the digital modulation for mobile radio use are described. Then, premodulation Gaussian filtered minimum shift keying (GMSK) with coherent detection is proposed as an effective digital modulation for the present purpose, and its fundamental properties are clarified with the aid of machine computation. The constitution of modulator and demodulator is then discussed from the viewpoints of mobile radio applications. The superiority of this modulation is supported by some experimental test results.

A system plan for a 900-MHz portable radio telephone

The system concepts for a high capacity personal radio telephone system are described. Previous systems for mobile radio telephone service have been based on a rigid assignment of frequencies to specific small geographic areas within the total coverage area. This approach has led to conservative geographic frequency reuse constraints and the requirement for accurate location techniques in the system. Through the utilization of the power imbalance that exists in the proposed portable radio telephone system between base and portable unit transmitters these constraints are eliminated. It will be shown how this power imbalance allows the selection of the optimum signal for the portable unit and relaxed requirements on location and reuse of frequencies. The required signal-to-interference ratios must be obtained within a design reliability level over the coverage area. Computer simulation of the frequency reuse plan and the propagation variability over the area indicates the nominal repeat intervals necessary as a function of this reliability level. A reuse plan that obtains the required repeat intervals with a high degree of spectral efficiency, through the combined use of geographic and frequency separation, will be presented. This system called tertiary offset, achieves a significant increase in interference protection by splitting each channel into a group of three channels and utilizing each subgroup in a different pattern of reuse over the area. The improvement due to this plan will be shown.

The Australian Telecommunications Network

The Australian Telecommunications Network, which is operated by the Government through the Postmaster-General's Department, is among the world's more advanced systems. Telephone, telegraph, and television services are provided to virtually all settled areas of the vast Australian continent. In very sparsely settled areas, outpost radio telephone services provide for essential communication. The manner in which the Australian network is being extended and modernized to meet the demands of the future is described. Reference is made to Australia's overseas telecommunications services and to the measures taken in the national system design to ensure compatibility with the world system.

H.F. maritime mobile services

The paper surveys the developments in the last 15 years of the h.f. ship-shore communication services provided in the United Kingdom by the Post Office. The first part of the paper deals with the radiotelegraphy services: the international planning at the Atlantic City Radio Conference in 1947; frequency-allocation problems; national planning in the United Kingdom; development of better radio equipments for coast and ship stations; the peace-time development of the joint Admiralty-Post Office Area Scheme for Commonwealth communication with British ships; and the new operational methods for handling the increased volume of traffic. The second part of the paper deals with the developments in the corresponding radiotelephone services with ships and the different frequency-planning and operational problems. The last part of the paper mentions briefly probable future trends, such as the introduction of single-sideband working in the telephony service, selective calling of ships by coast stations to minimize human watchkeeping, data transmission and the use of facsimile for transmission of charts and weather data.

Future Developments in Vehicular Communications

Starting from current trends in the field of land mobile radio-telephone services, primarily in the United States of America, forecasts of development over the next ten to twenty years have been made. It is estimated that by 1970 there will be two and a half million mobile telephones in the United States and over thirteen million by 1980. There is a discussion of the interrelated political, economic and engineering factors which will affect the future of vehicular communications. To meet user needs, coordinated broad-band systems are predicted for use cooperatively and on a common carrier basis with great efficiency of spectrum utilization. Currently, a broad-band system of 1000 channels could be accommodated in about 75 Mc of contiguous frequency spectrum in the lower part of the UHF band. It is conceivable that within the next two decades many more channels could be accommodated in a given bandwidth. Reducing the cost of mobile telephones is both necessary and capable of attainment. Pocket-size for a mobile telephone is indicated as probable during this period. New features for user convenience and better systems perfornance, such as full-duplex operation, push buttons for signaling, improved frequency stability, automatic channel selection and mobile station identification are predicted in coordinated systems within the next twenty years. y the IRE, June 26, 1961.

The use of level controlling devices in the radio-telephone service

This paper introduces the subject of speech level control as applied to radio-telephone service by presenting statistical data describing talker level variations and anticipated levels at the telephone central office. Because speech measurements are difficult to make, mention is made of speech to sine wave relationships that are convenient for system line-up. Next, maximum levels are established for the output of the controller and application to the wire-line or the radio transmitter. The operational characteristics of three available types of level controlling devices are discussed. These are: the Agamp and Vogad which were designed specifically for control of speech levels into radio transmitters; the clipper-limiter commonly used in radio broadcasting; and the Compandor which is familiar in telephone applications. Recordings were made of these devices in operation. Analysis of these recordings as related to the “ground rules” established in the text allowed conclusions to be drawn concerning the most advantageous use of each. In discussing the use of level controlling devices, it is necessary to determine the nature of the signals that are to be controlled. Where telephone facilities are to be used, consideration must be given to plant practices. These practices as well as the transmitter input requirements will establish the output level limits for the device. Having an idea of the input and output requirements and taking into account unusual noise and environmental conditions, the next step is to examine the characteristics, and cost of available units to determine the extent to which they meet the system application.

Pushbutton dial mobile radiotelephone an advanced concept in common carrier mobile service

A real need has developed for common-carrier mobile radiotelephone service which can be connected directly into dial telephone exchanges. Many exchanges are now unattended and the mobile subscriber must be able to dial his calls and receive calls in the same manner as with his office or home dial telephone. The transmission of the dialing information from a moving vehicle into the exchange, with the accuracy required to meet telephone standards, has presented an interesting challenge in view of various radio propagation characteristics often experienced, particularly from weak signal or fringe areas. The pushbutton type of dialing described in this paper provides a digital signalling system employing tones of sufficient duration to ride over the numerous signal drop-outs sometimes lasting more than 100 milliseconds. Extensive field experience has proven this approach to be highly reliable and consistent in dialing from a mobile unit. A unique application of counter tubes and transistor switching circuits is employed in the conversion of the tones into dial pulses at the base station terminal. The use of pushbuttons has been found to be very convenient for mobile service. A number of the various features incorporated in mobile dial systems are described in this paper.

Public air-ground telephone service trial

A survey of the growing need and problems of developing an air — ground radiotelephone service connected with the land-line telephone network.

Automatic mobile telephone system

Mobile radio-telephone service has been available to the American public since its inauguration in St. Louis in 1946. While this service is quite extensively in use today by mobile subscribers, and to some extent in rural areas, the present system requires an operator to complete the connection between a mobile and land subscriber. This paper covers a development of equipment that will work satisfactorily into present dial telephone equipment. The system has been developed for the telephone section of the Rural Electrification Administration, and was the result of work done in the laboratory since 1946. The pilot system originally was installed in the North Florida telephone company's property in Branford, Fla., and recently was transferred to the same company's exchange in Live Oak, Fla.

The use of level controlling devices in the radio-telephone service

This paper introduces the subject of speech level control as applied to radio-telephone service by presenting statistical data describing talker level variations and anticipated levels at the telephone central office. Because speech measurements are difficult to make, mention is made of speech to sine wave relationships that are convenient for system line-up. Next, maximum levels are established for the output of the controller and application to the wire-line or the radio transmitter. The operational characteristics of three available types of level controlling devices are discussed. These are: the Agamp and Vogad which were designed specifically for control of speech levels into radio transmitters; the clipper-limiter commonly used in radio broadcasting; and the Compandor which is familiar in telephone applications. Recordings were made of these devices in operation. Analysis of these recordings as related to the ground rules established in the text allowed conclusions to be drawn concerning the most advantageous use of each. In discussing the use of level controlling devices, it is necessary to determine the nature of the signals that are to be controlled. Where telephone facilities are to be used, consideration must be given to plant practices. These practices as well as the transmitter input requirements will establish the output level limits for the device. Having an idea of the input and output requirements and taking into account unusual noise and environmental conditions, the next step is to examine the characteristics, and cost of available units to determine the extent to which they meet the system application.

Overseas Radiotelephone Services of A. T. &T. Co.

Overseas Radiotelephone Services of A. T. &T. Co.

Experimental Radio-Telephone Service for Train Passengers

Experimental public radio-telephone service for train passengers was inaugurated by the Bell Telephone System several years ago. Initial installations operated in conjunction with a series of urban mobile base stations. More recently, highway mobile systems have been used for this service, and this paper describes a typical train installation operating through a highway channel. All of these early systems utilized an attendant on the train. The cost of providing an attendant has, in some cases, been found excessive. Consequently, experiments have been initiated in which a coin box is used on the train. The arrangements for this purpose are also described.

Vibrating reed selectors for mobile radio use

A new type of signaling system <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup> has been developed for mobile radiotelephone service in the Bell System. The basic selection of this system is performed by the use of vibrating reed selectors as described in this article.

V.H.F. radio equipment for mobile services

The first two Sections are introductory: the first explains the advantages of the V.H.F. band for local radio-telephone services to mobile vehicles, while the second briefly reviews some of the points which must be considered in planning such services.Most of the Paper is concerned with the design of suitable equipment. Sections 3 and 4 deal with the principal factors in the design of the mobile and fixed stations, respectively, and these are illustrated in Section 5 by a description of a particular range of equipment which has been produced commercially. In conclusion, there is a short discussion of future trends in development.

Railroad radio

A railroad radiotelephone service has been set up for use by railroad personnel to assist in railroad operations. Operating under rules of, and given a sizable number of frequencies by, the Federal Communications Commission, the railroads are using the new service in yards, terminals, harbors, and on main lines, as well as for emergencies. Equipment and housings have been designed to meet this new radio use.