JPH04267634A - Radio communication system - Google Patents

Abstract

PURPOSE:To relieve a line fault due to fading to the utmost with respect to the radio communication system used when a signal is sent through (N+1) radio lines in which fading possibly takes place, for example. CONSTITUTION:A transmission equalizer 32 of the same constitution as a reception equalizer section 42 is provided among a transmission equalizer control section 34, a modulation section 31 and a transmission section 33 at the sender side. When a reception equalizer control section 43 detects it that a detection level is almost made coincident with a preset level even while the quantization corresponding to a 1st control signal is implemented by the reception equalizer section, level difference information representing a level difference between the setting level and the detection level is sent to the transmission equalizer control section. The transmission equalizer control section sends a 2nd control signal corresponding to the received level difference information to the transmission equalizer section. The transmission equalizer section adds distortion corresponding to the impressed 2nd control signal to a digital modulation wave sent from a modulation section and sends the result.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless communication system used when transmitting signals over N+1 wireless lines where fading may occur, for example.

[0002] Normally, backup equipment using a different frequency is used to relieve deterioration in transmission quality or line disconnection caused by fading in the transmission line or failure of the active equipment that makes up the transmission line, or for maintenance of the active equipment. are prepared, and when a failure occurs on the working line or during maintenance, the line is switched to the backup line to prevent service interruption.

[0003] When fading occurs, if the spectrum distortion caused in the received signal cannot be equalized on the working line, the line is switched to the protection line, but since the routes are the same, it cannot be equalized even on the protection line. In many cases, it cannot be rescued.

[0004] Therefore, it is necessary to make it possible to relieve line failures due to fading as much as possible.

[0005]

2. Description of the Related Art FIG. 4 is a diagram for explaining line switching operation. Incidentally, in order to simplify the explanation, a working line 1 and a protection line 1 are shown.

First, when the working line is normal, on the transmitting side,
The line switching unit 11 performs processing necessary for transmitting the input main signal over the wireless line (for example, insertion of a frame synchronization signal, parity bit, etc.), and then sends it to the wireless transmitter 15.

[0007] A wireless transmitter generates, for example, a digitally modulated wave, converts it to a predetermined frequency and power, and transmits it to the receiving side. On the receiving side, the wireless receiving device 16 and the line switching unit 13 perform processing opposite to the processing on the transmitting side to reproduce the main signal and output it to the outside.

On the other hand, the output of the test signal oscillator 111 provided in the line switching section 11 on the transmitting side is transmitted to the wireless transmitter 1.
7 to the receiving side. On the receiving side, a test signal detector 131 detects a test signal passing through the protection line via the radio receiving device 18 and monitors the line status of the protection line.

Now, when the line switching unit 13 on the receiving side detects a line failure, this information is sent to the line switching control unit 14. After confirming that the protection line is normal and unused, the line switching control unit 14 sends a sending-end parallel transmission command to the sending side via the digital control line.

The line switching control unit 12 on the sending side detects the sending end parallel transmission command and switches the sending end parallel switch TS of the failed working line.
Drive W to send the main signal to the protection line as well. On the receiving side, when the main signal flowing through the protection line is confirmed, the receiving end changeover switch RSW is activated to complete line switching.

Next, FIG. 5 is a block diagram of a conventional wireless transmitting/receiving device, and FIG. 6 is an example of a block diagram explaining the configuration of an equalizer. It is an operation explanatory diagram. Note that the symbols on the left side of (B) in FIG. 6 indicate the waveforms of the portions with the same symbols in (A).

Now, in FIG. 5, the digital signal that has been subjected to the processing necessary for transmission over the radio line as described above is applied to the modulation section 21. The modulator 21 digitally modulates the carrier wave using this signal and sends it to the receiving side via the transmitter 22 at a predetermined frequency and power.

On the receiving side, a frequency conversion section 23 converts the received signal into a received signal in an intermediate frequency band and sends it to a reception equalization section 24 . Here, if fading does not occur in the wireless line, the spectrum of the received signal will be as shown in (B) in Figure 6.
As shown in the figure, the top surface is almost flat. However, when fading occurs, the frequency characteristics drop, as shown by the solid line (■) in FIG. 6(B), and the in-band amplitude characteristics deteriorate.

As shown in FIG. 6A, the receiving equalizer 24 also includes a parallel resonant circuit consisting of, for example, a coil L and a capacitor C1, a variable resistor R1 for varying the value of Q of this resonant circuit, and a variable resistor R1. It consists of a low-pass filter including a resistor R2 and a capacitor C.

Note that the capacitor C1 is a variable capacitance diode, and the variable resistors R1 and R2 are diodes. now,
Assume that a received signal with a drop in amplitude characteristics within the band is output without being equalized.

Narrowband bandpass filters 251 to 253 provided on the output side of the reception equalizer detect the levels of the spectrum in the vicinity of frequencies f2, f0, and f1 in the received signal, respectively, and perform equalization control. 254.

The equalization controller 254 has various level differences (
(becomes the read address)
1 and a ROM (not shown) in which control voltage values for variable resistors R1 and R2 are written.

[0018] Therefore, the CPU (not shown) reads out the control signal corresponding to the level difference and sends it to the reception equalizer, so that the drop is compensated for and the spectrum is adjusted as shown by the dotted line in Fig. 6(B). It becomes almost flat. The received signal whose spectrum has become almost flat is the demodulator 2 in FIG.
It is demodulated at 6.

[0019]

[Problems to be Solved by the Invention] Normally, when a failure occurs in the working line and the line is disconnected, the line is switched to a protection line to relieve the line failure.

Even when the working line is degraded due to fading, the reception equalization section compensates for the drop in the spectrum to improve the degradation, as described above. However, if fading occurs that exceeds the equalization capability of the reception equalizer, equalization becomes impossible, and the error rate deteriorates beyond a specified value, resulting in a line failure, and the line is switched to a protection line.

[0021] At this time, there is a problem in that even if the line is switched to the protection line, since the route is the same, fading that cannot be equalized occurs in the same way as with the working line, and relief cannot be recovered in many cases.

An object of the present invention is to make it possible to relieve line failures caused by fading as much as possible.

[0023]

[Means for Solving the Problems] FIG. 1 is a block diagram of the principle of the first invention. In the figure, 31 is a modulator that generates and transmits a digital modulated wave using an input signal, 33 is a transmitter that converts the digital modulated wave into a predetermined frequency and power, and transmits it, and 41 is a transmitter that converts the digital modulated wave into a predetermined frequency and power. This is a frequency converter that converts the received signal into an intermediate frequency band.

Further, 42 is a reception equalization section that equalizes the distortion of the reception signal in the intermediate frequency band in response to the first control signal applied, and 43 is a reception equalization section that equalizes the distortion of the reception signal of the reception equalization section in accordance with the first control signal applied. This is a reception equalization control unit that detects the level of a predetermined frequency and generates a first control signal.

Further, 34 is a transmission equalization control section, and 32 is a transmission equalization section having the same configuration as the reception equalization section between the modulation section and the transmission section. When the reception equalization control section detects that even if the reception equalization section is caused to perform an equalization operation corresponding to the first control signal, the detection level cannot be made to substantially match the preset setting level; Level difference information indicating a level difference between the set level and the detection level is sent to the transmission equalization control section, and the transmission equalization control section transmits equalization of a second control signal corresponding to the received level difference information. The transmission equalization section adds distortion corresponding to the applied second control signal to the digital modulated wave sent out from the modulation section and sends it out.

[0026] In a second aspect of the present invention, when the wireless communication device according to claim 1 is composed of n working transmitting devices and working receiving devices, and one backup transmitting device and one backup receiving device, the transmission equalization unit and a transmission equalization control section are provided in the backup transmitter.

According to a third aspect of the present invention, in the case of the wireless communication device according to claim 2, the transmission equalization section and the transmission equalization control section are provided in the current transmission device.

[0028]

[Operation] The first invention includes a transmission equalization control section on the transmission side;
A transmission equalization section having the same configuration as the reception equalization section is provided between the modulation section and the transmission section.

[0029] Here, due to fading, large distortion occurs in the spectrum of the received signal, and the reception equalization control section cannot make the detection level almost match the set level.
That is, in the case of insufficient equalization, the reception equalization control section sends level difference information indicating the level difference between the set level and the detection level to the transmission equalization control section.

The transmission equalization control section sends a second control signal corresponding to the received level difference information to the transmission equalization section. Therefore, the transmission equalizer adds distortion corresponding to the applied second control signal to the spectrum of the digital modulated wave sent out from the modulation section, and sends out the spectrum.

In other words, when the distortion in the spectrum of the received signal due to fading cannot be equalized by the reception equalization section alone, sufficient equalization can be achieved by performing equalization in both the reception equalization section and the transmission equalization section. It was made so that it could be done. This makes it possible to alleviate line failures caused by fading as much as possible.

[0032] In a second aspect of the present invention, when the wireless communication device according to claim 1 is composed of n active transmitting/receiving devices and one standby transmitting/receiving device, the transmitting equalization section and the transmitting equalization control section are Provided in the backup transmitter.

According to a third aspect of the present invention, in the wireless communication device according to claim 2, the transmission equalization section and the transmission equalization control section are provided in the current transmission device.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 is a block diagram of the first and second embodiments of the present invention, and FIG. 3 is a block diagram of a third embodiment of the present invention.

Here, the modulators 311 to 314 are constituent parts of the modulation section 31, the transmission equalizers 321 and 322 are constituent parts of the transmission equalization section 32, and the transmission equalization controllers 341 and 34.
2 is a component of the transmission equalization control unit 34, transmitters 331 to
334 is a component of the transmitter 33.

Further, frequency converters 411 to 414 are component parts of the frequency converter 41, and reception equalizers 421 to 4 are component parts of the frequency converter 41.
24 is a component of the reception equalization section 42, the reception equalization controller 4
31 to 434 are components of the reception equalization control section 43.

Note that the same reference numerals indicate the same objects throughout the figures. In the following, it is assumed that fading that cannot be equalized by the reception equalizer 422 occurs in the #1 working line.
Explain the operation.

First, in the #1 working line, the modulator 312 to which a digital signal that has undergone the processing necessary for transmitting the wireless line as described above digitally modulates a carrier wave using this signal. The signal is transmitted to the receiving side via the transmitter 332 at a predetermined frequency and power.

On the receiving side, a frequency converter 412 converts the received signal into a received signal in an intermediate frequency band, and then sends it to a receiving equalizer 422. The reception equalizer 422 equalizes the received signal and sends it out, but a part of it is similarly to the above, detects the level of the spectrum in the vicinity of a specified frequency in the received signal and sends it to the reception equalization controller 432. The remaining portion is then added to the demodulator 442 to extract the demodulated output.

The reception equalization controller 432 includes a ROM (not shown) in which control voltage values for controlling the resonant frequency and the Q of the resonant circuit are written in response to various level differences (which serve as read addresses). have.

Therefore, C in the reception equalization controller 432
The PU (not shown) reads out the control signal (which becomes the first control signal) corresponding to the level difference and sends it to the reception equalizer 422.
Send to. However, since fading occurred that exceeded the equalization capability of the reception equalizer 422, sufficient equalization was not performed and a drop remained, causing the error rate to deteriorate beyond the specified value.

Therefore, the CP in the reception equalization controller 432
U performs line switching control using error rate deterioration information (information for switching to a protection line) and level difference information indicating the difference between the detection level of the designated frequency of the output of the reception equalizer 422 and the above set level. 14.

Therefore, after confirming that the protection line is normal and unused, the line switching control unit 14 transmits level difference information and the like from the difference information transmitter 141 to the transmitting side via the digital control line in a predetermined format. Send.

Difference information receiver 121 of line switching control section 12
sends the received level difference information to a transmission equalization controller 341 having the same configuration as the reception equalization controller. The transmission equalization controller applies the level difference information as an address to a built-in ROM (not shown), reads out a second control signal for the corresponding resonance frequency and Q, and sends it to the transmission equalizer 321. Therefore, the transmission equalizer adds distortion to the spectrum of the digitally modulated wave in response to the applied second control signal and transmits the spectrum.

[0045] Thereby, the reception equalizer 421 can sufficiently equalize the received signal. In other words, when the distortion in the spectrum of the received signal due to fading cannot be equalized by the reception equalization section alone, sufficient equalization can be achieved by equalizing the reception equalization section and the transmission equalization section. This is what I did. This makes it possible to alleviate line failures caused by fading as much as possible.

FIG. 3 shows that when a state in which equalization cannot be performed due to fading occurs, the transmission equalizer and transmission equalization control section provided in the corresponding working line are used to restore the working line without switching to the protection line as described above. It is designed so that equalization can be performed on the line, and the operation is the same as that in FIG. 2.

[0047]

As described in detail above, according to the present invention, there is an effect that line failures caused by fading can be relieved as much as possible.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the principle of the first invention.

FIG. 2 is a block diagram of the first and second embodiments of the present invention.

FIG. 3 is a block diagram of a third embodiment of the present invention.

FIG. 4 is a diagram for explaining line switching operation.

FIG. 5 is a block diagram of a conventional wireless transmitting/receiving device.

FIG. 6 is an example of a block diagram illustrating the configuration of an equalizer;
(A) is a block diagram of the main part, and (B) is an operation explanatory diagram.

[Explanation of symbols]

31 Modulation section 32 Transmission equalization section 33 Transmission section 34 Transmission equalization control section 41 Frequency conversion section 42 Reception equalization section 43 Reception equalization control section

Claims (3)

[Claims] 1. On the transmitting side, a modulating section (31) that generates and transmits a digital modulated wave using an input signal, and a transmitting section (33) that converts the digital modulated wave into a predetermined frequency and power and transmits it. A transmitting device is provided, and on the receiving side,
a frequency converter (41) that converts a received signal into a received signal in an intermediate frequency band; and a reception equalizer (41) that equalizes distortion of the received signal in the intermediate frequency band in response to an applied first control signal. 42
) and a reception equalization control unit (
43), on the transmitting side, a transmission equalization control section (34), and a transmission, etc. having the same configuration as the reception equalization section between the modulation section and the transmission section. Kabe (
32), and the reception equalization control section cannot make the detection level substantially match the preset setting level even if the reception equalization section performs the equalization operation corresponding to the first control signal. When this is detected, level difference information indicating the level difference between the set level and the detection level is sent to the transmission equalization control section, and the transmission equalization control section transmits a second level difference information corresponding to the received level difference information. The control signal is sent to the transmission equalization section, and the transmission equalization section adds distortion corresponding to the applied second control signal to the digital modulated wave sent out from the modulation section and sends it out. Wireless communication method. [Claim 2] The wireless communication device according to Claim 1 has n (n≧2
(a positive integer) of active transmitting devices and active receiving devices, and one backup transmitting device and one backup receiving device,
A wireless communication system characterized in that the transmission equalization section and the transmission equalization control section are provided in a backup transmission device. 3. The wireless communication system according to claim 2, wherein the transmission equalization section and the transmission equalization control section are provided in a working transmitter.