DK163161B - CAR PHONE SYSTEM WITH BOTH VHF AND UHF CHANNELS - Google Patents

Abstract

1. Mobile telephone system with stationary and mobile subscriber stations in the wide area of a land mobile network, consisting of a plurality of base stations in a mutual spatial arrangement, characterized by two radio sections in the respective radio equipment, of which one is active in the VHF region in thinly populated areas and works with a high transmitting power, and the other is active in the UHF range in densely populated areas and works with a relatively low transmitting power, and by a controller which monitors both radio sections according to predetermined criteria and activates a switch-over when necessary, and which at the same time activates the data signalling between base station and mobile station.

Description

DK 163161 B

The invention relates to a car telephone system with stationary and mobile subscriber stations in a large area of the radio, the radio network comprising several radio concentrators with a spatial connection to one another.

5 'In older systems relatively low frequencies (VHF range) are used, which offers the advantage of having a relatively wide range. These systems, which are known e.g. of the 29th IEEE Vehicular Technology Conference, March 1979, pages 245 to 252 (especially Fig. 1 with 10 accompanying description page 245), New York, U.S., H.H. Callendar et al: "Network design for a fully automatic wide area radiotelephone service", suitable for rural areas, however, allows only relatively few channels. Thus, a cellular system is not achievable in this frequency range.

Newer systems, also known from the above article (see Fig. 2 and accompanying description), use transmission channels in the UHF area. These offer high channel capacities in conjunction with a diminished range, making them suitable for densely populated areas of low range. For radio coverage of rural areas, many fixed stations have to be set up due to the small range.

DE-A-2 659 570 describes a telephone system with 25 fixed and mobile subscriber stations in a large area of the radio, which consists of several types of radio concentrator areas arranged in a cellular system with overlapping radio areas. In this connection, these first radio concentrator regions in areas of particularly high subscriber density are superimposed on other radio concentrator regions with substantially larger range radii, and with, in these regions not yet used, their own frequencies. The other radio concentrator areas are associated with the relevant mobile subscriber stations, which are only intended for information traffic within this radio concentrator area.

Further, EP-A-0 111 164 discloses a radio system which extends a public telephone system via mobile

DK 163161 B

2 recipients and radio call centers, each associated with a call region. With the aid of a radio call center, calls that come directly or indirectly from the telephone network can be transmitted as call telegrams in a radio network, in order to trigger the broadcast of a radio call. In this connection, for several immediately adjacent and overlapping transmission areas, the same transmission frequency, called national frequency, has been used for the transmission of radio calls, for which decoupling in different overlapping regions there are different cyclically repeated time windows in the individual transmission areas. Further, in a transmitting area, another transmission frequency, called home frequency, may be transmitted, in particular to this transmitting area, for broadcasting radio calls to such receivers, which are constantly in this transmitting area only. For broadcasting the home frequency, there are several synchronously working home transmitters in a transmission area, for transmission of the national frequency there are several mutually synchronous working transmitters in the transmission areas. As a 20-call receiver, there are two types, namely one which is fixedly tuned and only for receiving a home frequency suitable, one-channel receiver and one type which is also, or as fixed-tuned one-channel receiver, exclusively suitable for receiving the national frequency.

The object of the invention is to provide a solution for a uniform radio system to cover an area of different population density.

This task is solved according to the invention by a car telephone system with two radio parts in the individual radio devices, one of which works in the VHF area, is active in sparsely inhabited areas and works with high transmit power, and the other works in the UHF area, is active in densely populated areas and operating at relatively low transmit power, and a control which monitors both radio parts and, if necessary, causes a switching, the control simultaneously causing the data signaling between radio concentrator and mobile station.

Claims (2)

15 This will preferably take place in urban areas. With this control, it is ensured that the low-frequency channels, of which there are only a few, are also only coated if no high-frequency channels (the UHF area) can be coated. This will include be the case in rural areas. The switching can also be performed during a call. A car telephone system with stationary and mobile subscriber stations in a large area of the radio, the radio network comprising several radio concentrators with a mutual spatial connection, characterized by two radio parts in the individual radio devices, one of which operates in the VHF area, active in sparsely inhabited areas 30 and works with high transmit power, and the other works in the UHF area, is active in densely populated areas and works with relatively low transmit power, and a control which monitors both radio parts and, if necessary, causes a switching, the control simultaneously causing then-35 the signaling between radio concentrator and mobile station.