JPS6138892B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a diversity method used to improve the reliability of a line using a non-line-of-sight communication method (hereinafter referred to as a "non-line-of-sight communication line") in a wireless multiplex communication line. It is.

In non-line-of-sight communication lines, single reception requires extremely large transmitters and antennas to compensate for drops in received input fluctuations. For this reason, it is possible to take advantage of the fact that there is little correlation between fluctuations in two signals received by two antennas with a sufficient spatial distance, or fluctuations in signals of different frequencies received by the same antenna. A diversity reception method is used in which a number of signals with little correlation between fluctuations are received simultaneously by combining these signals, and the best signal is always used for communication. Second or fourth order diversity is commonly used.

In non-line-of-sight communication lines using such diversity methods, the propagation loss changes with weather changes, so the line is designed to compensate for the propagation characteristics during the worst period on the worst day throughout the year.
During normal hours, there is sufficient bandwidth on the line, making frequency use uneconomical.

For example, when designing a quadruple diversity communication line to meet the international standard line quality 99.9% of the time per year, if the annual long-term fluctuation can be approximated by a normal distribution with a standard deviation of 10 dB, then Even with double diversity on this line, the line quality can be satisfied 99.7% of the year. Also the standard deviation
Even at 5dB, the line quality can be satisfied 99.1% of the time. Therefore, maximum performance is required only 0.2% (with a standard deviation of 10 dB) or 0.8% (with a standard deviation of 5 dB) of the year.

In this way, during times when the propagation loss is relatively small and reception conditions are good, the order of the diversity method used is lowered by one step, and the resulting surplus route is used as a parallel line to generate a new signal. By transmitting, it can be used as a line with double or quadruple the transmission capacity.

With this method, without major modification of conventional equipment,
Since it is possible to transmit signals of 2 routes or 4 routes, it is possible to configure a meridian line. In this case, when the line quality deteriorates, the parallel line returns to diversity use, so it is no longer possible to transmit another signal on the parallel line, but this time rate is very small, so it is effectively doubled or quadrupled. It can be operated as a double line. Channels accommodated in parallel lines that become unusable when the diversity order increases are preferably set to automatically become busy.

That is, the present invention increases the transmission capacity by transmitting separate signals to some or all of the plurality of lines during most of the time when the quality of the received signal is good and using the lines as parallel lines. It is characterized in that when the quality of the received signal deteriorates, these lines are subjected to diversity and controlled to increase the degree of diversity.

Next, it will be explained in detail with reference to the drawings of the embodiment.

FIG. 1 is a configuration diagram of an embodiment of the present invention. An example in which the present invention is implemented in a non-line-of-sight communication line using a quadruple diversity system that combines two spatially separated antennas and two radio frequencies will be shown. In FIG. 1, S-1 indicates an input/output signal of the first route, S-2 indicates an input/output signal of the second route, and S ₁ and S ₂ indicate switching circuits. When this switching circuit is switched to terminal 1, only the signal S-1 of the first route is transmitted, and when switched to terminal 2, the signal S-1 of the first route and the second route is transmitted.
-1 and S-2 are transmitted simultaneously.

The signal path when the switching circuits S ₁ and S ₂ are switched to terminal 1 is as follows. That is, the output signal S-1IN of the first route passes through the branch circuit H, one of the branched signals is transmitted by the transmitting circuit T-1 to the other station as a signal of radio frequency _f1 or _f3 , and the other is switched. The signal passes through circuit _S1 and is transmitted to the other station as a signal at radio frequency _f2 or _f4 by transmitting circuit T-2. The received signal is branched into radio frequencies f ₁ and f ₂ or f ₃ and f ₅ by a branching circuit B, and then sent to receiving circuits R-1, R-2, R-3, and R-.
4, the output signal of the receiving circuit for each same radio frequency is sent to each combining circuit (C-1 or C-
2). The output signals of the synthesis circuit are synthesized again by the synthesis circuit C-3, and the output signal S-
Get 1 OUT.

The signal path when the switching circuits S ₁ and S ₂ are switched to terminal 2 is as follows. That is, the input signal S-1IN of the first route passes through the branch circuit H, and is transmitted to the other station as a signal of radio frequency _f1 or _f3 by the transmitting circuit T-1, while the input signal S-2IN of the second route passes through the switching circuit S ₁ and the transmission circuit T
-2, the signal is transmitted to the other station as a signal at radio frequency f ₂ or f ₄ . The received signal is sent to branching circuit B.
to the radio frequencies f ₁ , f ₂ or f ₃ , f ₄ respectively
receiving circuits R-1, R-2, R-3,
R-4, the output signal of the receiving circuit for each same radio frequency is sent to each combining circuit (C-1 or C
-2). 1st route (radio frequency
The signal of f ₁ or f ₃ ) passes through the combining circuit C-1 and becomes the output signal S-1 OUT through the combining circuit C-3, and the signal of the second route (radio frequency f ₂ or f ₄ ) passes through the combining circuit C-3. -2 and then passes through the switching circuit _S2 to become the output signal S-2OUT.

Next, the switching operation of the switching circuit is as follows.
Monitoring circuit DET added to receiving circuit R-1
Detects the received input electric field level value or the received input noise level value. When the level value changes from a good state, that is, a state in which the signals of the first route and the second route are transmitted simultaneously, to a state in which the level value becomes worse than the preset level value, or in a bad state, that is, only the signal of the first route is transmitted. When the current state becomes better than the set level value, a signal is sent from the monitoring circuit DET to the control circuit CONT. The control circuit CONT that received the signal
controls the switching circuits S ₁ and S ₂ and the switch SW according to the procedure shown in FIG. 2 or 3. In this case, the control circuit of either station
When CONT sends a control signal to the other station's control circuit CONT, the control signal is sent to the line monitoring control circuit.
It is assumed that the signal passes through the SV and is sent to the partner station via this wireless line (first route). Furthermore, the monitoring circuit and control circuit of one of the stations is given superiority over the circuit of the other station. The entire line is controlled by the circuit that has this advantage, and if a failure occurs in the circuit that has this advantage, the circuit of the other station takes control of the entire line.

Figure 2 shows the line configuration that transmits only the signal S-1 of the first route (when the terminal of the switching circuit is at 1), the signal S-1 of the first route and the second route,
It shows the flow of control signals when switching to a line configuration (in the case of terminal 2 of the switching circuit) that simultaneously transmits S-2.

In FIG. 2, [M] indicates a station whose monitoring circuit and control circuit have superiority over the circuits of the other station, and [S] indicates the other station. Here the monitoring circuit
First, the signal from DET [M] is sent to the control circuit CONT
[M], and is switched from terminal 1 to terminal 2 in the order of switching circuit S ₂ and then switching circuit S ₁ by a control signal from the control circuit. As a result, a control signal indicating that the second route can be used is sent from the control circuit to the exchange SW.

Figure 3 shows the signal S of the first route and the second route.
-1 and S-2 at the same time (when the terminal of the switching circuit is on 2) to a line configuration that transmits only the first route signal S-1 (when the terminal of the switching circuit is on 1) The flow of control signals when switching is shown.

In FIG. 3, [M] indicates a station whose monitoring circuit and control circuit have superiority over the circuits of the other station, and [S] indicates the other station. Here, first from the monitoring circuit DET [M], the control circuit CONT
A signal is sent to [M], and the control circuit sends a control signal indicating that the second route cannot be used to the switch SW, and the switch confirms that the second route is not in use and then controls it. respond to the circuit. Therefore, the control circuit sends out a control signal to switch the switching circuits S ₁ and S ₂ from terminal 2 to terminal 1.

As described above, when the reception condition of the line is good, the transmission capacity can be increased to twice that of the conventional method.

As explained above, by lowering the diversity order of the diversity method used in non-line-of-sight communication lines, when the received signal is good, it is possible to reduce the number of signals from two routes or from four routes, that is, to It has the advantage of being able to transmit signals with twice or four times the transmission capacity. The present invention is extremely economical because it can be implemented without major modification of conventional equipment.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an embodiment of the present invention, and is a circuit diagram of a quadruple diversity type non-line-of-sight communication line that combines two antennas and two radio frequencies. FIG. 2 is a diagram showing the flow of control signals when switching from terminal 1 to terminal 2 of the switching circuit. FIG. 3 is a diagram showing the flow of control signals when switching from terminal 2 to terminal 1 of the switching circuit. H...branch circuit, T-1 and T-2...transmission circuit, B...branching circuit, R-1, R-2, R-3
and R-4...receiving circuit, C-1, C-2 and C-3...combining circuit, DET...monitoring circuit,
CONT...Control circuit, SV...Line monitoring control circuit, SW...Switchboard, S-1IN...Input signal of first route, S-1OUT...Output signal of first route, S-2IN...Second Root input signal, S-
2OUT... Second route output signal, f ₁ , f ₂ , f ₃ ,
f ₄ ...Radio frequency of transmission or reception, [M] ...
Station whose control circuit has superiority [S]...its partner station, solid arrow in the flowchart...control signal, dotted arrow...response signal.

Claims (1)

[Claims] 1. In a diversity system for line-of-sight communication that monitors the quality of each received signal on multiple transmission lines and switches the transmission line to be used based on the monitored output, if the quality of the received signal is good, the quality of each received signal is switched. Non-line-of-sight communication characterized in that a separate signal is transmitted to a parallel line, and when the quality of the received signal deteriorates, the plurality of transmission lines are controlled to provide diversity to increase the diversity order. diversity method.