JPH0356495B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field] The present invention relates to a line switching device, and particularly to a line switching device that performs high-speed switching between active and backup lines in a digital wireless communication system. [Background of the Invention] In digital wireless communication systems, a line switching system that uses electronic circuits and is capable of high-speed operation is employed in order to perform synchronous switching of uncoded errors as a means of line maintenance and countermeasures against fading. In this line switching method, one transmission data switching circuit is inserted into the modulator input of the backup radio line on the transmitting side, and
In the preliminary configuration system, all the data signal lines of each modulation input of the n working radio lines are branched and connected to this transmission data switching circuit, and selective connection is performed by the control signal. ,
A large number of data signal lines and control signal lines are concentrated in the transmission data switching circuit. In recent years, the development of orthogonal multi-level modulation has progressed, but in orthogonal multi-level modulation, the number of data signal lines used for modulation and demodulation of one radio channel is large (for example, in 8-phase PSK, there are only two data signal lines 3 lines for 16-value QAM, 4 lines for 64-value QAM
(6), when the number n of wireless lines is large (for example,
In the 11GHz band radio frequency allocation, there are up to n = 11)
The disadvantage of conventional methods is that the number of data signal lines and control signal lines that go in and out of the transmission data switching circuit is extremely large, resulting in implementation difficulties such as a lack of connector pins and a lack of mounting space. be. [Object of the Invention] An object of the present invention is to eliminate the drawbacks of the above-mentioned conventional methods and to provide a line switching device that can be applied to a digital wireless communication system using orthogonal multilevel modulation. [Structure of the Invention] The line switching device of the present invention is a line switching device that switches between working and standby in a digital wireless communication system consisting of at least one standby radio line and a plurality of working radio lines. A plurality of data switching circuits are provided, each of which selects each set of one signal line group by a control signal and connects to one set of second signal line group; The second signal line group of the data switching circuit is connected to the modulation device or demodulation device of the backup radio channel, and the second signal line group of each data switching circuit except the first data switching circuit is connected to the connected sequentially to one set of the first signal line group of other data switching circuits including the first data switching circuit;
The signal line groups are connected to the input or output data signal line groups of the working or standby wireless line, respectively, and each data switching circuit except the first switching circuit performs selective connection by a control signal. The data switching circuit is constructed by using a response signal shown as a control signal of the other data switching circuit to which the second signal line group of this data switching circuit is connected. [Prior Art] Next, the present invention will be described in detail with reference to the drawings.
First, in order to facilitate understanding of the present invention, a conventional line switching system will be explained. Figure 1 shows the backup radio line SP and n working radio lines REG1, REG2,
. . . is a block diagram showing a configuration example of a conventional line switching system used in a digital wireless communication system with an n:1 configuration consisting of REGn. In FIG. 1, a bipolar input signal 100 for each working radio line sent from a multiplexer (not shown) is as follows:
The signal is divided into two by a branch circuit 1, and one is sent to a relay switch 2 and the other to a transmission signal processing circuit 3. The latter undergoes necessary code processing such as bipolar/unipolar conversion, speed conversion, code string conversion, and insertion of monitoring bits and frame synchronization signals in the transmission signal processing circuit 3, and is then processed in m columns (m is 8-phase PSK), each indicated by a double line. In the case of QAM, it is converted to a baseband signal 101 of 3, 4, etc. in the case of 16-value QAM. The baseband signal converted into m columns of unipolar signals passes through the transmission distribution circuit 4 to the transmitting device 5 of each working wireless line.
is added to perform orthogonal multilevel modulation on each radio carrier.
On the other hand, each m-column baseband signal 102 branched by the transmission distribution circuit 4 is connected to a transmission data switching circuit 6 provided between the transmission signal processing circuit 3' and the transmission device 5' of the backup radio line SP. has been done. The transmission data switching circuit 6 normally switches the monitoring data signal generated by the pilot generation circuit 7 to the backup radio line.
However, the baseband signal 102 of each working wireless line is sent to the backup wireless line in parallel using a control signal 103.
In this configuration, in addition to the baseband signal input/output for the backup radio line, the transmission data switching circuit 6 receives baseband signals and control signals from each working radio line, and at least m(n+2) baseband signals are concentrated on the transmission data switching circuit 6. It is necessary to connect the band signal line to n control signal and response signal lines. Therefore, when the number of parallel baseband signal trains m and the number of active wireless lines n are large, it becomes difficult to secure a mounting location for the connectors due to the increase in the number of required connectors and the increase in the number of connector pins, making implementation design difficult. It has the disadvantage of becoming. On the receiving side, the demodulated output of the receiving device 8 of each working radio line is supplied to the received signal processing circuit 11 via the synchronization switching circuit 10 together with the timing signal (bit and frame synchronization signal) regenerated by the frame synchronization circuit 9. Here, the signal is subjected to the reverse code processing as on the transmitting side and converted into a bipolar signal 104, and then sent through the relay switch 12 to a multiplexer (not shown). On the other hand, the demodulated output of the backup radio line receiving device 8' is sent to the reception distribution circuit 1 along with the timing signal regenerated by the frame synchronization circuit 9'.
3. It is connected to the pilot detection circuit 14 via the received signal processing circuit 11', and is configured to normally detect the monitoring data signal and monitor the status of the backup radio line. When switching from active to standby, first the baseband signal of the active radio line to be switched is sent out in parallel to the standby radio line on the transmitting side. The demodulated output and timing signal of the backup radio channel are branched from the reception distribution circuit 13 and sent to each synchronization switching circuit 10, and each synchronization switching circuit 10 synchronizes the timing of the demodulated baseband signals of the working and backup, respectively. The control signal 105 is configured to instantly switch from active to standby, and to perform synchronous switching for unsigned errors. The control signal 105 is sent to the received signal processing circuit 1
1 and 11' confirm that the current and backup baseband signals match for a certain period of time before being transmitted. In this configuration on the receiving side, the reception distribution circuit 13 also handles the baseband signal and timing signal line for the backup radio line, as well as each synchronization switching circuit 1.
The signal lines 106 to 0 are concentrated, and there is a problem similar to that on the transmitting side (the receiving distribution circuit may have a switching function). Note that the relay switching devices 2 and 12 are provided for failures in the transmission signal processing circuit 3, the synchronous switching circuit 10, the reception signal processing circuit 11, and the like. [Embodiment] FIG. 2 is a block diagram of an embodiment of the present invention, showing a transmitting side line switching device with a 5:1 working/standby configuration. In FIG. 2, three transmission data switching circuits 15-1, 15-2, and 15-3 each have three sets of input signal lines (first signal line group) Ai that transmit m columns of baseband signal inputs. , Bi, and Ci by a control signal and selectively connects them to the m-column baseband output signal line (second signal line group) Di, and the transmission data switching circuit 15-
The output signal lines D ₂ and D ₃ of the transmission data switching circuits 2 and 15-3 are sequentially connected to the input signal lines C ₁ and C ₂ of the other transmission data switching circuits 15-1 and 15-2, respectively. The output signal line _D1 of the first transmission data switching circuit 15-1 inserted into the backup wireless line is connected to the modulator input of the SP.
The input signal line A ₁ is connected to the SP transmission signal processing circuit 3', and the input signal line B ₁ is connected to the REG 1 transmission distribution switch 16-.
The input signal lines A ₂ , B 2 and A 3 , B 3 of the transmission data switching circuits 15-2 and 15-3 are connected to the branch output G ₁ of the transmission data switching circuit 15-2 and 15-3, and the input signal lines A 2 , B ₂ and A ₃ , B ₃ of the transmission data switching circuits 15-2 and 15-3 are connected to the transmission distribution switch 16-2, 16 of each working wireless line. -3, 16-4, 16-5 branch outputs G ₂ , G ₃ and G ₄ , G ₅ respectively. Currently, the working wireless line REG5 is being used as a backup wireless line.
Consider the case of switching to SP. Control line 103-5
When a signal is applied to the transmit distribution switch 16-
5 operates to branch the baseband signal 101-5 from the transmission signal processing circuit 3 to _G5 and send out the control signal 107-5 to the transmission data switching circuit 15-3. Transmission data switching circuit 15-3 selects input B ₃ based on this control signal, connects it to output D ₃ , and sends response signal 108-3 to transmission data switching circuit 15-2. Transmission data switching circuit 1
5-2 similarly selects the input _C2 , connects it to the output _D2 , and sends out the response signal 108-2 to the transmission data switching circuit 15-1. Similarly, the transmission data switching circuit 15-1 selects input C ₁ and outputs it.
Connect to D ₁ , open input A ₁ of SP by response signal 108-1, and connect baseband signal 1 of REG 5.
01-5 are sent in parallel to REG5 of SP. The same applies to the case where other working radio lines are switched to backup, and the output 1 of the transmission signal processing circuit 3 of each working radio line REGi is controlled by the control signal 103-i.
01-i is sent in parallel to the SP. According to this circuit, the transmission data switching circuit 1 inserted into the SP
5-1 has three sets of baseband signal input lines A ₁ ,
B ₁ , C ₁ , baseband signal output line D ₁ , and a small number of control signal lines are only connected, and the number does not increase even if the number of active wireless lines n increases. Can be removed. Furthermore, since each working wireless line is provided with a transmission distribution switch 16-i, the signal is transmitted to each transmission data switching circuit 15-i.
-i in cascade, the S/N ratio will not deteriorate due to addition of crosstalk noise due to leakage. FIG. 3 is a concrete block diagram of one embodiment of the control signal system of FIG. 2, and the same symbols as in FIG. 2 are used for each circuit and signal. Each control signal 103
-i is at "H" level under normal conditions, and a control signal for switching is given at "L" level.
The branch gate 17 of each transmission distribution switch connects the input Ei to the output Fi and the branch output Gi when the control terminal gi is at the "H" level, and connects the input Ei to the output Fi and the branch output Gi when the control terminal gi is at the "L" level.
connected only to Transmission data switching circuit 15-
Each selection circuit 18 of i has a corresponding control terminal ai, bi,
Open when ci is at “H” level, “L”
When the level is reached, the corresponding input is connected to the output Di. _C3 of the transmission data switching circuit 15-3 is not used in this embodiment, and the "H" level is always applied to the control input 109 of _C3 . The control input 110 of the transmission data switching circuit 15-1 is also “H”
level is added and outputs SP input A ₁ when normal
Although connected to D ₁ ,

[Table] When either 107-1 or 108-2 goes to "L" level, _a1 goes to "H" level and the protection line input is disconnected. Table 1 shows the state of each control signal 103-i for parallel transmission from each working radio line REGi to the backup radio line SP, and each transmission data switching circuit 15-i which becomes "L" level at this time.
The control terminal of the selection circuit 18 of i and the control terminal of the branch gate 17 that goes to "H" level are shown. FIG. 4 is a block diagram of an embodiment of the receiving side line switching device corresponding to FIG. The input signal line (second signal line group) Di′ that transmits signals and timing signals is connected to three sets of output signal lines (first signal line group) Ai′, Bi′, and Ci′ by control signals. A data switching circuit for selective connection, which is a receiving data switching circuit 19-3, 1.
The input signal lines D ₃ ′ and D ₂ ′ of 9-2 are the output signal lines C ₂ ′ and 19-1 of the received data switching circuits 19-2 and 19-1, respectively.
connected sequentially to C ₁ ′. The input signal line _D1 ' of the first received data switching circuit 19-1 inserted into the backup radio line is connected to the demodulator output via the frame synchronization circuit 9', and the output signal line _A1 ' is connected to the received signal processing circuit. 11', B ₁ ' is the synchronous switching circuit 10- of REG1.
1, respectively. Output signal lines A ₂ ′, B ₂ ′ and
A ₃ ′ and B ₃ ′ are connected to synchronous switching circuits 10-2, 10-3 and 10-4, 10-5 of each working radio line, respectively. As in the case of Figure 2, use REG5.
The case of switching to SP will be explained. As described above, the baseband signal of REG5 is branched from the transmitting side and transmitted in parallel to the SP. When synchronization is established in the frame synchronization circuit 9' of the SP, the control signal 111-5 is sent to the reception data switching circuit 19-3.
, the input signal line D ₃ ' and the output signal line B ₃ ' are connected, and a response signal 112-3 is sent to the received data switching circuit 19-2. As a result, the received data switching circuit 19-2 connects the output signal line C ₂ ′ to the input signal line D ₂ ′ and sends the response signal 112-2 to the received data switching circuit 19-1. The received data switching circuit 19-1 selects the output signal line C ₁ ', connects it to the input signal line D ₁ ', and sends out the response signal 112-1. The output of SP is now connected to the synchronous switching circuit 10-5 of REG5, and the baseband signal of REG5 is sent in parallel to the respective received signal processing circuits 11 and 11' via REG5 and SP, preparing for synchronous switching. It's all set. Next, as in the conventional method shown in FIG. 1, the received signal processing circuits 11 and 11' compare the data for a certain period of time to confirm that parallel transmission is being performed, and then control signal 105-5 is used to confirm that parallel transmission is being performed. The synchronous switching circuit 10-5 is activated and the path of the baseband signal is switched to via the SP, thereby completing the synchronous switching for uncoded errors. According to this configuration, the first received data switching circuit 19-1 has A ₁ ′, B ₁ ′,
It is only necessary to connect four sets of input/output signal lines C ₁ ', D ₁ ' and a small number of control signal lines, and the drawbacks of the conventional method shown in FIG. 1 are eliminated. FIG. 5 is a concrete block diagram of an embodiment of the control signal system of the reception data switching circuit shown in FIG. 4, which is almost the same as the transmission data switching circuit shown in FIG. 20 is the selection circuit 1 in FIG.
8 and the signal transmission direction is reversed. Similar to FIG. 3, the selection circuit 20 is configured to connect the corresponding output to the input depending on the "L" level of the control signal, and connects the unused output signal line C ₃ ' of the reception data switching circuit 19-3 to the input. An "H" level voltage is applied to the control input 113 of. Further, an output is always sent to the output signal line A ₁ ' to which an "L" level voltage is applied to the control signal terminal a ₁ ' of the reception data switching circuit 19-1. Table 2 shows the states of each control signal and the control terminals of the selection circuit 20 that are at the "L" level, similar to Table 1.

〔Effect of the invention〕

As described in detail above, according to the line switching device of the present invention, a plurality of data switching circuits with a small number of selections are sequentially connected in cascade, and are sequentially controlled by the response signal of each data switching circuit. This has the effect of eliminating the concentration of baseband signal lines and control signal lines and facilitating implementation design.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a line switching system in a conventional digital wireless communication system, Fig. 2 is a block diagram of an embodiment of the present invention on the transmitting side, and Fig. 3 is an embodiment of the control signal system of Fig. 2. 4 is a block diagram of an embodiment of the present invention on the receiving side, FIG. 5 is a block diagram of an embodiment of the control signal system of FIG. 4, and FIG. 6 is a block diagram of an embodiment of the present invention on the receiving side. FIG. 3 is a block diagram of another embodiment. 1... Branch circuit, 2, 12... Relay switch,
3, 3'... Transmission signal processing circuit, 4... Transmission distribution circuit, 5, 5'... Transmission device, 6, 15-i...
Transmission data switching circuit, 7... Pilot generation circuit, 8, 8'... Receiving device, 9, 9'... Frame synchronization circuit, 10, 10-i... Synchronization switching circuit, 1
1, 11'... Reception signal processing circuit, 13, 21...
...reception distribution circuit, 14...pilot detection circuit,
16-i... Transmission distribution switch, 17... Branch gate, 18, 20... Selection circuit, 19-i... Reception data switching circuit.

Claims (1)

[Claims] 1. In a line switching device that switches between active and standby in a digital wireless communication system that includes at least one standby radio line and a plurality of working radio circuits, each set of the plurality of first signal line groups is connected to a control signal. a plurality of data switching circuits selected by a group of second signal lines and connected to a set of second signal line groups; The second data switching circuit of each data switching circuit other than the first data switching circuit is connected to the modulation device or demodulation device of the backup radio channel.
are sequentially connected to one set of the first signal line groups of other data switching circuits including the first data switching circuit, and each of the first signal line groups of the plurality of data switching circuits other than the above The signal line groups are connected to the input or output data signal line groups of the working or standby wireless line, respectively, and each data switching circuit except the first switching circuit performs selective connection by a control signal. A line switching device characterized in that the line switching device is configured to use a response signal shown as a control signal for the other data switching circuit to which the second signal line group of the data switching circuit is connected.