JP2500781B2 - Line switching device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line switching device, and more particularly to a line switching device for switching a plurality of working lines and protection lines of different modulation / demodulation systems of a digital radio communication system at a predetermined time.

[0002]

2. Description of the Related Art Conventionally, in a microwave band wide band digital radio communication system, a working M line (M ≧ M) is used for maintenance and inspection of the radio line and for fading countermeasures.
1), a line switching device is known in which one line is provided and a predetermined one line in the working line is switched to the backup line without interruption during a predetermined time (for example, JP-A-59-413).
35, JP-A-1-170147, etc.).

FIG. 3 is a block diagram showing an example of such a conventional line switching device. In the figure, N (where N ≧ 1 is a natural number) input terminals are respectively connected to the sending end switches 2 ₁ to 2 _N. The sending end switching devices 2 _{1 to} 2 _N are input terminals 1 ₁ to
The input signal from 1 _N is input to the first modulators 4 ₁ to 4 _N , while the pilot signal from the pilot signal generator 3 is input to the first modulator 9.

The signals digitally modulated by the first modulators 4 ₁ to 4 _N and taken out are converted into microwave band signals by the corresponding first transmitters 5 _{1 to} 5 _{N and then} transmitted by radio. Are received by the first receivers 6 _{1 to} 6 _N. The signals received by the first receivers 6 _{1 to} 6 _N are
After being demodulated by the first demodulators 7 _{1 to} 7 _N , the demodulated signals are input to the receiving end switching devices 8 ₁ to 8 _N.

On the other hand, the output signal of the first modulator 9 is converted into a microwave band signal by the first transmitter 10, then wirelessly transmitted, received by the first receiver 11, and further transmitted by the first receiver 11. The data is demodulated by the demodulator 12 and then input to the receiving end switches 8 ₁ to 8 _N. The receiving end switches 8 ₁ to 8 _N normally output the demodulated signals from the _first demodulators 7 _{1 to} 7 _N to output terminals 14 _{1 to} 14 _N.
And the demodulated signal from the first demodulator 12 to the pilot signal detector 13.

Accordingly, usually along with the input signal from the input terminal ₁ 1 to 1 _N is output to the output terminal ₁₄ 1 to 14 _N through working N lines, the pilot signal is input to the pilot signal detector 13 via the stand 1 line As a result, it is monitored whether or not the protection line is normal.

In such a (1 + N) line digital radio communication system, the line quality of the working N lines is the code error rate of the demodulated signals from the _first demodulators 7 _{1 to} 7 _{N for} each working line. It is monitored by comparing it with a predetermined reference value in 8 ₁ to 8 _N. When a code error rate is more deteriorated than the reference value, the other line (not shown) feed edge switch 2 _1, utilizing (FIG. 3 downlink When uplink)
Out of 2 _N , the transmission end switch of the working line whose line quality has deteriorated is controlled so that the working signal is also transmitted to the protection line.

Therefore, for example, when the line quality of the first working line from the input terminal 1 ₁ to the output terminal 14 ₁ is deteriorated, the sending end switch 2 ₁ modulates the working signal from the input terminal 1 ₁ by the first modulation. and inputs to the vessel 4 _1, also entering the working signal from the input terminal 1 ₁ to the first modulator 9 in place of the pilot signal.

As a result, the demodulation working signal from the _first demodulator 7 ₁ and the demodulation preliminary signal from the first demodulator 12 are input to the receiving end switching unit 8 ₁ , respectively.
After receiving end switch ₈₁ is the combined phases of these signals, switches without interruption to the protection line from a working line.

[0010]

However, while the modulation method of the working line differs depending on the relay interval and the frequency band used by the user, the above-mentioned conventional line switching device has a different modulation method between the working line and the protection line. Since the propagation delay time of the signal differs due to the difference in the modulation method, the receiving end switching device cannot perform phase matching between the working signal and the backup signal, and thus the line cannot be switched without interruption.

Therefore, conventionally, it is necessary to use the same modulation method for the working line and the protection line. Therefore, a line switching device having the same configuration as that of FIG. 2 must be provided for each working line modulation system. In addition, there is a problem that the frequency utilization efficiency is low.

The present invention has been made in view of the above points,
An object of the present invention is to provide a line switching device that solves the above problems by providing a delay adjuster for time adjustment on the working line.

[0013]

In order to achieve the above-mentioned object, the present invention modulates an input signal inputted through a first transmission end switching device by a first modulation method and then wirelessly transmits and receives the signal. One or more first working lines that demodulate the signal and output to the first output terminal through the first receiving end switch, and an input signal that is input through the second sending end switch One or two or more second working lines that perform wireless transmission / reception after being modulated by a modulation system different from the first modulation system, demodulate the received signal, and output to the second output terminal through the second receiving end switching device. , First
A signal input through at least one of the first and second transmission end switching devices, is modulated by the first modulation method, and then wirelessly transmitted and received, and the received signal is demodulated to obtain the first and second reception end switching devices. In order to correct the delay time difference due to the difference between the protection line input to at least one side and the modulation method of the protection line and the second working line, the receiving side of the second working line or the first working line and the protection line It is configured by a delay adjuster provided on each receiving side.

[0014]

In the present invention, since the modulation schemes of the second working line and the protection line are different from each other, even if a propagation delay time difference occurs on the transmission signals of both lines, the second working line is used by the delay adjuster. The line and the standby line can be time-aligned, and therefore the phases of the demodulated signals from both lines can be aligned in the second receiver switching unit.

[0015]

1 is a block diagram of the first embodiment of the present invention.
In the figure, parts that are the same as the parts shown in FIG. 3 are given the same reference numerals, and descriptions thereof will be omitted. In FIG. 1, the input terminal 1 _{N + 1} is connected to the second modulator 21 via the sending end switch 2 _{N + 1} . In the second modulator 21 is a circuit for performing the digital modulation of the second modulation scheme different from the first modulator 4 ₁ to 4 _N and 9, carried out, for example, 8-phase phase modulating (8PSK). The first modulation scheme according to a first modulator 4 ₁ to 4 _N and 9 performed, for example 64 quadrature amplitude modulates (64QAM).

The output signal of the second modulator 21 is converted into a microwave band signal by the second transmitter 22, wirelessly transmitted, received by the second receiver 23, and further received by the second demodulator. After being demodulated by 24, it is input to the delay adjuster 5.
In the delay adjuster 25, the second modulator 21 modulates the input signal by the second modulation method different from the first modulation method, so that the output modulated wave has the first modulators 4 ₁ to 4 _N and Assuming that the propagation time of the output modulated wave of 9 is faster by τ seconds, the delay time is set to τ seconds.

The output end of the delay adjuster 25 is the receiving end switch 8
It is connected to _{N + 1} . The receiving end switch 8 _{N + 1} outputs the demodulated signal from the second demodulator 24, which is normally delayed by the delay adjuster 25, to the output terminal, like the receiving end switches 8 ₁ to 8 _N. Also, the demodulated signals from the first demodulator 12 that are input via the receiving end switches 8 ₁ to 8 _N are output to the pilot signal detector 13.

Therefore, in this embodiment, one working line of the second modulation system is provided in the digital radio communication system in which one working line of the first modulation system is provided with one protection line of the first modulation system. It has a different structure. Also in this embodiment, the line quality of the working line is demodulators 7 _{1 to} 7 _N and the delay adjuster 2 for each working line.
The code error rate of each demodulated signal from 5 is received end switching devices 8 ₁ to 8
It is monitored by comparing it with a predetermined reference value at _{N + 1} .

[0019] When the code error rate has deteriorated than the reference value, the feed edge switch 2 ₁ to utilize the other line (not shown)
Of the 2 _{N + 1} , the transmission end switch of the working line whose line quality has deteriorated is controlled so that the working signal is transmitted in parallel to the protection line.

Here, for example, when the line quality of the working line of the second modulation system from the input terminal 1 _{N + 1} to the output terminal 14 _{N + 1} deteriorates, the sending end switch 2 _{N + 1} causes the input terminal 1 _{N + 1}
While inputting the working signal from the second modulator 21,
The input terminal 1 is also provided to the first modulator 9 instead of the pilot signal.
Input the working signal from _{N + 1} .

As a result, the demodulated signals of both the working line and the protection line, which have been demodulated and then demodulated by different modulation systems, are input to the receiving end switch 8 _{N + 1.} Since the demodulation working signal from the device 24 is input in time with the demodulation signal of the protection line by the delay adjuster 25, the receiving end switch 8 _{N + 1} can match the phases of both demodulation signals. , When the phases match, the working line is switched to the protection line without interruption.

Therefore, according to the present embodiment, even if the modulation schemes of the working line and the protection line are different, it is possible to switch the lines without interruption by providing only one protection line for the working line of each modulation method. It can be performed. For this reason, it is possible to eliminate the need for many protection lines that have conventionally been required to be provided corresponding to the modulation scheme of the working line.

FIG. 2 shows a block diagram of the second embodiment of the present invention. In the figure, the same components as those in FIG.
The description is omitted. In this embodiment, instead of the Nth working line of the first modulation system from the sending end switch 2 _N to the receiving end switch 8 _N of the first embodiment, a working line of the third modulation system is provided. It is what

That is, according to the present embodiment, the signal input from the transmission end switch 2 _N receives the third modulator 31, the third transmitter 32, the third receiver 33, and the third demodulator. The signal is input to the delay adjuster 35 through the device 34, and then to the receiving end switching device 8 _N. Here, the third modulator 31 is a modulator that performs modulation by a third modulation method (for example, 16QAM) different from the first and second modulation methods.

Further, the delay adjuster 35 is the third modulator 31.
Propagation but to modulate an input signal by the third modulation scheme different from the first and second modulation scheme, the output modulated wave is output modulated wave of the first modulator 4 ₁ to 4 _N and 9 If the time is, for example, τ ₁ second faster, the delay time is set to τ ₁ second.

As a result, also in the case of the present embodiment, when the working line of the third modulation system deteriorates in line quality below a predetermined value, the demodulation working signal from the third demodulator 34 is delayed by the delay adjuster. Since the demodulated signal of the protection line is input by time 35, the receiving end switching unit 8 _N can match the phases of these two demodulation signals, and when the phases match, the protection line is switched from the working line to the protection line. It can be switched to without interruption. Therefore, this embodiment also has the same effect as the first embodiment.

The present invention is not limited to the above embodiments, and when the propagation delay time of the protection line is shorter than that of the working line, a delay adjuster is provided on the receiving side of the protection line. Of course. Further, as the modulation method, in addition to the above-mentioned modulation methods, a multi-valued quadrature amplitude modulation method of 128 values or more and a phase modulation method such as 4-phase PSK can be considered.

[0028]

As described above, according to the present invention,
Even if there is a difference in the propagation delay due to the difference in the modulation method between the working line and the protection line, the delay adjuster adjusts the propagation delay time and the signal phase of the working line and the protection line is matched by the receiving end switch. Therefore, it is possible to switch the line without interruption by providing only one protection line for the working line of each modulation method. Therefore, only one protection line is provided for each wireless digital system of each modulation method, and the others can be omitted, so that the frequency utilization efficiency can be improved as compared with the conventional technology.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a conventional example.

[Explanation of symbols]

2 _{1 to} 2 _{N + 1} sending end switching device 4 ₁ to 4 _N , 9 first modulator 5 _{1 to} 5 _N , 10 first transmitter 6 _{1 to} 6 _N , 11 first receiver 7 ₁ to 7 _N, 12 first demodulator 8 ₁ to 8 _{N + 1} receiving end switch 21 and the second modulator 22 second transmitter 23 and the second receiver 24 and the second demodulator 25 and 35 delay adjuster 31 Third Modulator 32 Third Transmitter 33 Third Receiver 34 Third Demodulator

Claims (2)

(57) [Claims] 1. An input signal input via a first transmission end switch is modulated by a first modulation method and then wirelessly transmitted / received, and the received signal is demodulated to a first reception end switch through a first reception end switch. Wireless transmission / reception after modulating an input signal input via one or more first working lines to be output to the output terminal and a second transmission end switcher by a modulation system different from the first modulation system. At least one of the second working lines that demodulates the received signal and outputs the demodulated signal to the second output terminal through the second receiving end switch, and at least the first and second sending end switches. A signal input through one side is modulated by the first modulation method, wirelessly transmitted and received, and the received signal is demodulated to generate the first and second signals.
Of the protection line input to at least one of the receiving end switches, and in order to correct the delay time difference based on the difference in modulation method between the protection line and the second working line, the receiving side of the second working line or the above A line switching device comprising: a first working line and a delay adjuster provided on each receiving side of the protection line. 2. The first or second receiving end switcher monitors the line quality deterioration of the connected working line, and when the line quality deterioration occurs, the signal input to the working line. Are input to the protection line in parallel, and then the demodulation signal of one of the working line and the protection line that has deteriorated in line quality and that is input through the delay adjuster and the delay adjuster are input. 2. The line switching device according to claim 1, wherein the line is switched to the protection line after the phase of the demodulated signal of the other line which is not present is matched.