Showing papers on "Mobile telephony published in 1981"

The concept of an integrated terrestrial/land mobile satellite system

Abstract: 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.

Satellite-aided mobile communications: Experiments, applications, and prospects

Abstract: NASA's application technology satellites (ATS) were used in a series of communications and position-fixing experiments with automotive vehicles, ships, and aircraft. Applications of the communications were demonstrated and evaluated for public services including law enforcement, search and rescue, medical emergency, and for commercial uses in the land and maritime transportation industries. The technical success of the experiments and the demonstrated potential value of the communications prompted a study that concluded an operational satellite-aided system would be a valuable augmentation of planned trunking or cellular-type terrestrial mobile radio telephone systems.

Statistical analysis of communications range and reliability in the presence of interference

Abstract: A statistical method is developed for analysis of interference in land mobile communications systems Reduction of communication range and degradation of system reliability are calculated This method can be used for cases in which a desired signal is transmitted by a base station (or mobile unit) and received by a mobile unit (or base station) and is interfered with by a signal transmitted either by a fixed station or a mobile unit The spatial probability distribution of mobile units is considered The method is applicable to any frequency band for which path loss statistics are known, and an example of this method is given which calculates reduction in communication range, area, and degradation of communication reliability for different values of splatter protection, and distributions of mobile units

Some uses of CATV technology in land mobile communications

Abstract: Many land mobile system designers and users do not realize that CATV technology can provide a means of solving system problems. This paper will describe how CATV equipment and networks can be used to expand traditional land mobile services and to encourage designers to explore uses for CATV technology in innovative system development. Off the shelf hardware, including CATV amplifiers used for amplifying mobile radio signals in long transmission lines and FM multiplexing equipment for multiplexing two way voice, video and data on the same line will be described.

Channel assignment schemes and traffic capacities of mobile radio systems

Abstract: In this paper, we examine the spectrum efficiency of various land mobile radio system approaches in terms of traffic capacity for a given number of channels. Spectrum Efficiency can also be described in terms of Communication Capacity of the system per unit bandwidth. To determine the number of users a system can support for a given grade of service, both aspects (traffic handling and communication) should be considered simultaneously. In the first part of this paper we examine the traffic capacity of cellular mobile radio systems with different channel assignment schemes. It is shown that cellular systems are superior to trunked systems with moderate frequency reuse but not without frequency reuse. However, with use of effective channel assignment schemes, cellular system's performance is close to that of trunked systems even without frequency reuse. Adaptive channel assignment schemes are examined. Adaptive shcemes are based on the fact that traffic intensity of the arrival process varies slowly with time. Therefore, channels can be assigned to take the maximum advantage of the random nature of the arrival process and the frequency reuse at a given time. Traffic capacity of the mobile radio system is examined which uses the same set of channels to service the different classes of users. One such example is the mobile radio system which provides voice-telephone and dispatch service on the same channels. Arrival process is assumed to be Poisson for both telephone and dispatch calls with different arrival rates. Service rates are also different for the telephone and dispatch calls. Blocked telephone calls are cleared from the system and blocked dispatch calls are delayed. Another example is a mobile radio system which services different classes of users with different service times and grades of service.

Measuring system of reception electric field level in mobile communication

Abstract: PURPOSE:To make unnecessary the receiver for electric field monitor, by adding a multichannel switching reception function to a communication channel transceiver equipped with a radio base station and using a receiver not used for communication as reception electric field level measurement. CONSTITUTION:When a mobile station in a service area 1 moves from radio zones A-C to other radio zones while being in communication state, the necessity of switching of radio lines to a radio base station 3 of the mobile station is caused. Accordingly, to monitor the transmission wave of the mobile station ahead it, with the instruction from a radio contrl station 4, the reception electric field level for the transmission waves from the mobile station is measured at a bundle, by using the multichannel switching reception function of transceivers in vacant, not used for communication, at the time point, among transceivers equipped with the radio base station 3.

Channel control system of mobile communication

Abstract: PURPOSE:To use the radio channel efficiently, by extracting and selecting one of stored channel numbers at random for originating of the mobile station to determine the originating channel. CONSTITUTION:For originating of the mobile station, one of contents in storage device 5 is extracted by random extracting circuit 6 on the basis of the command of control device 7, and the frequency of synthesizer 10 is set to the extracted channel, and the originating operation and the calling state are set with this radio chanel. In this case, the base station device stops transmission of the number of this radio channel when accepting the cal from the mobile station and adds a new channel number in stead of this channel number and reports new callable channel number S-CH information of another mobile station through the control channel. Consequently, the probability where two or more mobile stations originate with the same channel at the same timing is reduced.

Parallel processor network architecture for real-time information systems within mobile communications systems with large numbers of subscribers

Abstract: The parallel processor network architecture has a plurality of hierarchically arranged levels which are designed in such a way that the management units (processors, auxiliary processing devices, switching networks etc.) present in the individual levels can be varied according to the number of subscribers and processing power. The structure enables the management or switching control (handling) of very large numbers of subscribers (approx. 10 million subscribers).

The Impact of the 1979 World Administrative Radio Conference on the Fixed-Satellite, Inter-Satellite, and Mobile-Satellite Services

Abstract: The Fixed-Satellite service (FSS) is the most heavily used and still the fastest growing of the seventeen space radio communications services recognized by the International Telecommunication Union (ITU). To provide the additional spectrum needed for continued growth in both domestic and international satellite networks, the ITU's 1979 World Administrative Radio Conference (WARC-79) more than doubled the bandwidth allocated to this service in most parts of the spectrum. The Inter-Satellite service (ISS) is an "auxilliary" service whose allocations are intended to provide intersatellite links between the space stations of other services. Although not yet implemented in commercial systems, such links are expected to be used extensively in future FSS networks. To permit the introduction of the ISS earlier and at lower cost than would be possible with the existing allocations above 50 GHz, WARC-79 allocated two 1-GHz-wide bands to the ISS at 23 and 33 GHz. The Mobile-Satellite services (MSS) include land, maritime, and aeronautical components. WARC-79 left the Aeronautical-Mobile Satellite allocations essentially unchanged, created new possibilities for development in the Land-Mobile Satellite service, and essentially doubled the spectrum that will be available to the Maritime-Mobile Satellite service. WARC-79 made only minor changes to the regulatory procedures for gaining access to the various space service allocations. However, in response to the concerns of developing nations about equitable access to the spectrum and the geostationary satellite orbit for future satellite systems, WARC-79 resolved to convene another World Administrative Radio Conference in two sessions scheduled for 1984 and 1985 (WARC-84/85). This Space Conference would consider the use of the geostationary satellite orbit and the planning of the space services using it with the objective of guaranteeing in practice for all countries equitable access to the orbit. This paper provides a detailed description of the WARC-79 allocation actions affecting the FSS, ISS, and MSS and provides background on the decision to convene WARC- 84/85.

Satellite augmentation of terrestial cellular mobile radio telephone systems

Abstract: Cellular type mobile radio telephone systems offer the potential for higher capacity and better service than is now available. Terrestrially-based systems will be cost effective in densely populated areas, but could leave most of the land area without service. Satellites appear to offer a cost effective means to serve thinly populated areas, so a combined terrestrial and satellite system may provide an ubiquitous mobile telephone service. Reliable, good quality voice communications have been relayed through NASA's ATS satellites with mobile equipment adapted from commercially available units, demonstrating that the terrestrial and satellite cellular systems can be compatible. Vehicle position surveillance by voice bandwidth ranging from the satellites was shown to be practical and potentially accurate to about 1/10 mile. Mobile satellite communications were tested for long distance transportation, remote area search and rescue, and used for medical emergencies and disasters including the Mt. St. Helens eruption. The success of the ATS experiments has encouraged NASA to initiate studies to assess requirements, develop concepts, and plans for a multibeam demonstration satellite. International interest is evident in the 1979 WARC authorization for satellite mobile in the cellular band (806-890 MHz) and in joint Canadian/NASA discussions on the possibility of a multi-beam satellite to serve Canada and the United States.