Transmission base for a radio telephonic communication arrangement.

Base station for radiotelephone system

The invention relates to a base station for a radiotelephone traffic system.

Such radiotelephone communication systems are known, which comprise, when installed in fixed locations, a plurality of base stations connected to the telephone network and intended to establish radio connections to a series of vehicle stations moving in the area covered by the radiotelephone communication system. In known systems, the base station includes at least one receiving antenna for receiving radio signals; a receiver connection portion connected to the receiving antenna; a set of receiver parts connected to this part of the receiver connector; a series from the processing unit connected to the respective receiver parts, the telephone network line and the control unit; a series of transmitter components connected to digital processing units; a transmitter connection part connected to the transmitter parts and a transmission antenna connected to the transmitter connection part.

In addition, in order to achieve secure transmission between a base station and vehicle stations, regardless of radio obstructions that may exist between the base station and vehicle stations, such as unfavorable terrain or various radio canopy structures, it is known to prefer to use frequency hopping in different ways.

In order to perform frequency hopping using existing base stations having the structure outlined above, the transmitter interface part must necessarily be a broadband part operating in hybrid form. The disadvantage of such interfaces is that they cause a power loss as a function of the number of stages of the base station, so that base stations intended to transmit a large number of calls simultaneously must initially produce very high powers.

In order to reduce the required power while still maintaining the frequency hops, it has been proposed to group the receiver and transmitter parts together into common modules with hollow interfaces.

However, such a system requires the installation of an extremely complex switching matrix to provide connections between the transmitter / receiver modules and the digital processing units.

It is an object of the invention to provide a base station which is relatively simple in structure and can easily operate in connection with both a broadband and a cavity type transmitter interface part.

To achieve this object, the invention provides a base station for a radiotelephone communication system which includes at least one receiving antenna for receiving radio signals; a receiver connection portion connected to the receiving antenna; a series of receiver25 connected to the connector part; a series from the processing unit connected to the respective receiver parts, the telephone network line and the control unit; a series of transmitter components connected to digital processing units; a transmitter interface part connected to the transmitter parts and a transmission antenna connected to the transmitter connection part, the system being characterized in that the digital processing units are connected to the transmitter parts by a series of connecting lines each connecting line which connects one of the interconnectors to the relevant transmitter section.

In a preferred embodiment of the invention, wherein the transmitter interface portion is of the hollow type with each transmitter portion adapted to transmit a signal at a fixed frequency, each selector portion includes means for detecting a relay message received from a digital processing unit. with.

In a preferred embodiment of the invention, in which the transmitter interface part is of the cavity type and is intended to ensure constant beacon frequency transmission, the beacon frequency transmitter part transmits a payload signal each time data occurs on one of the beacon frequency transmission lines, there is no data on the transmission line for transmission.

In an embodiment of the invention where the transmitter interface part is of the hybrid type, each selector part establishes a permanent connection to one of the connecting lines.

In a preferred embodiment of the invention, in which the transmission takes place at a number of frequencies greater than the number of digital processing units, in which the transmitter interface part is of the hybrid type and permanently transmitted at the signal frequency, the base station includes a signal frequency transmitter part in addition to the selector part, including means for detecting messages to be transmitted from all digital processing units and for causing the fill signals to be transmitted at the signal frequency when none of the other transmitter parts are transmitted at the signal frequency.

Other features and advantages of the invention will become apparent from the following description of a preferred embodiment of the invention, which is not intended to limit the invention, together with a single figure of the accompanying drawings, which is a block diagram illustrating the structure of a base station of the invention.

It can be seen from the figure that the base station of the invention comprises a receiving antenna 1 for receiving radio signals, a receiving part n 2 connected to the receiving antenna and a series of receiving parts 3 connected to the receiving connection part.

In the embodiment shown, the number of receiver parts is limited to three, but naturally this number can be increased as a function of the number of calls transmitted at the base station.

connected to the digital voice network controller 6.

Each of the receiver parts 3 is connected to a processing unit 4, a line 5 and a common one

The receiver interface unit 2 operates in hybrid form and each of the receiver parts is at all times ready to receive radio waves at the carrier frequency assigned to it by the associated digital processing unit and based on control signals provided by the control unit in which the frequency hopping rules are set. The receiver parts 3 are thus able to amplify the received radio signals in a conventional continent and convert them into digital signals, while the digital processing units decode the received digital signals and transmit them to the telephone network, said received digital signals per se connecting several calls using conventional time division multiplexing techniques.

Each digital processing unit 4 is further connected to a corresponding line in a series of connecting lines 7 connected in parallel for transmitting messages to the transmitter parts 8. Each message to be transmitted contains data to be transmitted, information on the frequency at which the data is to be transmitted and other data, eg is due to happen. Each of the transmitter par ts 8 i s connected in parallel to all the connecting lines, and the selector parts 9 select which of the connecting lines 7 is connected to the respective transmitter part. The transmitter parts 8 are connected to a transmitter connection part 10, which in turn is connected to a transmission antenna 11.

In a preferred embodiment of the invention, the transmitter interface part 10 is of the cavity type, i.e. each transmitter part 8 associated with the interface part 10 is adapted to transmit a signal at a fixed frequency. In this case, the number of transmitter parts 8 is a function of the number of fixed frequencies at which the transmission is to take place. Although the number of transmitter parts 8 in this particular example is limited to four in order to simplify the pattern, this number can be increased or decreased as a function of the frequencies to be transmitted, the minimum number being equal to the number of digital processing units. In addition, the control unit 6 synchronizes the digital processing units 4 so that at any one time only one digital processing unit transmits a message to be transmitted comprising a given transmission frequency. Each digital processing unit staggers the frequency hops over time according to predetermined rules loaded into the control unit when the hardware is installed. In this embodiment, each selector section includes means for detecting transmitted messages from the digital processing units to determine which of the digital processing units is connected to the transmitter 8 to which the selector section is associated. Each time the selector section 9 indicates that data is to be transmitted on the frequency of the transmitter section to which the selector section is connected, the selector section connects it to the corresponding connecting line.

In this way, the combined transmitter part in a characteristic manner and transmits a signal to the transmission antenna 11, a modulated useful signal.

processes the data in a conventional manner which is then radiated by someone

In order to achieve a constant transmission at a signal frequency, in which the vehicle stations use the signal frequency as a reference even when no data is transmitted, one of the transmitter parts is naturally tuned to the signal frequency, and this transmitter transmits a useful signal each time there is no modulated signal to be transmitted at the character frequency. Depending on the decisions made in the design of each system, the fill signal may be an unmodulated transmission at the signal frequency or it may be a transmission modulated according to system-specific rules.

Although the preferred embodiment of the base station 5 of the invention is used in connection with a cavity-type interface to reduce the power required for operation, the base station of the invention can be easily adapted to operate with a hybrid-type transmitter interface 10. In this case, each selector part 9 is controlled to ensure that a permanent connection is established to one of the connecting lines 7, and the base station then operates in the same way as a conventional base station having the structure outlined at the beginning of this description. In this case, the number of transmitter parts 8 can be limited to the number of digital processing units 4. However, when the number of frequencies on which the transmission takes place is larger than the number of digital processing units, and when it is also desired to ensure a constant transmission with a signal frequency, it is preferable to provide The selector section 9 associated with the padding transmitter section then includes means for detecting messages to be transmitted from all digital processing units to ensure that the padding signal is transmitted at the mark frequency whenever none of the transmitter units transmit a signal at the mark frequency. It should be noted that in this case, the base station of the invention has an additional advantage over conventional base stations, where the signal frequency must be connected to a complete line comprising a receiver part, a digital processing unit and a transmitter part.

The invention is, of course, not limited to the described embodiment, and various variations can be developed therefrom while remaining within the scope of the invention.

For example, although in the described embodiment there is one telephone line 5 connected to each digital processing unit 4, a single telephone line can be connected to several processing units depending on the respective capacities of the telephone line and the digital processing units.