JPH01200841A - System for switching frequency - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] "Industrial Application Field" The present invention relates to a frequency switching method when setting up a communication line using time-divided communication channels over multiple frequencies. .

"Prior Art" FIG. 1 is a diagram showing a conventional frequency switching system,
-4 are n fixed frequency frequency oscillators, 5 is an oscillator switching circuit, and 6 is a frequency conversion circuit.

In the method shown in the figure, the frequency is switched as follows to convert the IF frequency to the RF frequency.

For n oscillators 1 to 4, the oscillator-specific frequency f1
, f2, fi, and fn signals, respectively. The switching circuit 5 selects one of the n frequency oscillators and outputs the oscillation signal of the selected frequency oscillator. The frequency conversion circuit 6 mixes the oscillation signal received from the switching circuit 5 and the IP times signal of frequency fXF and converts the mixture into an FtF signal of frequency fRr.

``Problems to be Solved by the Invention'' In such conventional frequency switching systems, the frequency of the oscillator is fixed, so in order to enable transmission and reception on all communication channels on the frequency-divided communication line, it is necessary to , the same number of frequency oscillators as the number m of frequency divisions of the communication line are required, and there is a problem that the amount of hardware of the communication device increases. Furthermore, if the number n of oscillators possessed by the transmitting and receiving nodes is limited to a number smaller than the number m of frequency divisions,
Communication can only be carried out between nodes that have oscillators of the same frequency, and the number of frequencies that can be assigned to each node is small (this has the disadvantage of increasing the call loss rate and reducing line usage efficiency).

An object of the present invention is to lower the call loss rate compared to conventional systems and to improve communication line utilization efficiency when the number of oscillators in one transmitting/receiving node is limited to less than the number of frequency-divided communication lines. The objective is to provide a frequency switching method that can set the frequency.

"Means for Solving the Problem" In the frequency switching method of the present invention, a plurality of transmitting/receiving nodes each have one system of transmitting/receiving equipment, and the frequency is divided into m waves, which are further divided into m waves in time by t.
In a method of performing communication by setting a communication line according to a request using t communication channels, n pieces (I≦n<m) of variable frequency frequency oscillators that can be set to any frequency, and the frequency One of the output signals of the variable frequency oscillator
It is composed of an oscillator switching circuit that selects one output signal, and a frequency conversion circuit that converts the frequency based on the output of the oscillator switching circuit, and changes the frequency of the Moeki frequency variable frequency oscillator every time the communication line is set. It is characterized in that each sending and receiving node communicates using an arbitrary communication channel.

"Operation" The frequency switching method of the present invention uses a variable frequency oscillator whose oscillation frequency can be arbitrarily set as a frequency oscillator. However, by changing the frequency of the frequency oscillator, it is possible to set up a communication line using any communication channel, lowering the call loss rate and increasing line usage efficiency.

"Example" FIG. 1 is a diagram for explaining the present invention in detail,
In the figure, 1l-(4 is a variable frequency frequency oscillator, 15 is an oscillator switching circuit, 16 is a frequency conversion circuit, and 17 is a frequency control circuit.

The frequency variable type frequency oscillators 11-14 generate arbitrary frequencies f and fa by control signals from the frequency control circuit 17.
These are n wavenumber oscillators that oscillate signals of t, fi, and fn, respectively. The oscillator switching circuit 15 connects the frequency oscillators 11 to
The frequency conversion circuit 16 selects one of the 14 signals, and the frequency conversion circuit 16 mixes it with the output signal of the IP multiplication signal switching circuit 15 of the frequency for to convert the signal into an RF multiplication signal of the frequency fRr. With such a configuration, by setting the frequency corresponding to the communication channel in the frequency oscillators 11 to 14 and controlling the switching circuit 15, the communication line is frequency-divided by n oscillators less than the number m. , it becomes possible to set up communication lines between sending and receiving nodes using all communication channels. Therefore, communication is possible between any nodes, and even if all the communication channels on the assigned frequency are occupied by lines between other nodes, if there are free communication channels on other frequencies, It becomes possible to newly allocate and use that frequency. Therefore, the call loss rate can be lowered and line usage efficiency can be improved.

FIG. 2 shows the relationship between communication channels and transmitting/receiving nodes when a communication line is set up using the configuration shown in FIG.

In the same figure, t1 to t are divisions on the time axis, f1 to f
3 is division on the frequency axis. However, the number of frequency divisions of the communication line is 3, the number of time divisions is 5, and the number of frequencies assigned to one transmitting/receiving node is 2. Here, attention is paid to the transmitting/receiving node A which sets the frequency of its frequency oscillator to the frequencies f1 and f2 of the communication channel at time T. At this time, communication channels A1 to A5 or frequency f,
and f, and the frequency oscillator is switched between tt and fs and between ta and ta. The shaded areas are channels for which communication lines have been set up by other nodes, and the blank areas are channels for which no lines have been set up.

Now, at time T2, communication on communication channels A3 and A4 has ended, and due to a call request from another node, f, A3 above
, A4 is set to another line. and,
If a call request is made to node A at subsequent time T3,
Since all communication channels of frequency ft are already used by other nodes, node A sets the frequency of the frequency oscillator that was set to frequency f to f3, and the switching timing of the frequency oscillator remains the same, and the communication Channel 86
, A7's communication line is set up.

From the above, it can be seen that by using this method, the hardware is reduced and the line usage efficiency is improved compared to the conventional method.

FIG. 3 shows the relationship between the number of frequency oscillators each transmitting/receiving node has and the call loss rate when a communication channel is set using this method. The solid line is an example of the frequency switching method of the present invention, and the broken line is an example of the conventional fixed frequency switching method. Here, the number of frequency divisions of the communication line is 8, the number of time divisions is 30, and the number of transmitting/receiving nodes is 200, and the ratio of the number of communication channels required for line setup is 1:6:24. It is assumed that 0.8 erls (equivalent to low-speed calls) occur per node with a constant call volume ratio. In the figure, high-speed calls, medium-speed calls, and low-speed calls are indicated by 1 and 2.3, respectively.

As is clear from this figure, by using this system, it is possible to provide a communication line with a lower call loss rate compared to conventional systems.

"Effects of the Invention" As explained above, the frequency switching method of the present invention allows the oscillation frequency of the variable frequency oscillator to be changed when the number of frequency oscillators in each transmitting/receiving node is less than the number of frequency divisions of the communication line. Because of switching, compared to the conventional fixed frequency switching method, it is possible to reduce the amount of hardware, lower the call loss rate, and provide a communication line with high line usage efficiency.

[Brief explanation of the drawing]

FIG. 1 is a block configuration diagram for explaining the present invention in detail, FIG. 2 is an explanatory diagram of the relationship between a communication channel set using the frequency switching method of the present invention and a transmitting/receiving node, and FIG. 3 is a diagram of the present invention. FIG. 2 is an explanatory diagram of the relationship between the number of frequency oscillators that one node has and the call loss rate when a communication channel is set using . FIG. 4 is a block diagram for explaining the conventional frequency switching method. 1114...n variable frequency frequency oscillators, 15... frequency switching circuit, 16... frequency conversion circuit, 17... frequency control circuit. @Figure 2

Claims (1)

[Claims] A plurality of transmitting/receiving nodes each have one system of transmitting/receiving equipment, and the frequency is divided into m waves, which is further divided into t in terms of time, m×
In a method of performing communication by setting a communication line according to a request using t communication channels, n pieces (1≦n<m) of variable frequency frequency oscillators that can be set to any frequency, and the frequency One of the output signals of the variable frequency oscillator
It consists of an oscillator switching circuit that selects one output signal, and a frequency conversion circuit that converts the frequency based on the output of the oscillator switching circuit. A frequency switching method characterized in that transmitting and receiving nodes communicate using arbitrary communication channels.