JPH10112721A - Output signal delay correcting system of transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct an output signal without increasing the size of an circuit when each station is connected to a transmission line in a ring shape and when an output signal of each slave station which receives an NNI(network node interface) signal outputted from a master station is delay-corrected. SOLUTION: When data is distributed between adjacent slave stations 2n and 2n+1 through a route 1, the slave station 2n adjusts phase to a reference signal from a reference signal generating part 26 and outputs data, while the slave station 2n+1 adjusts phase to a reference signal from a reference signal generating part 29 and outputs data. The deviation between the reference signal from the part 26 of the station 2n and the reference signal from the part 29 of the station 2n+1 is shifted only by the delay of a transmission line between both stations 2n and 2n+1 because both stations 2n and 2n+1 are adjoined each other. Because of this, the phase difference of output data between the stations 2n and 2n+1 can be restrained within the transmission line delay between the stations 2n and 2n+1 .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ring-shaped SDH (Synchronous Digital).
Hierarchy Network NNI (Network)
A transmission system in which a master station and each of a plurality of slave stations, each of which is a digital transmission device, are connected to a transmission path through which a Node Interface (Signal Interface) signal is transmitted. The present invention relates to an output signal delay correction method for delay-correcting a received signal from a master station such that a delay between an output signal of an arbitrary slave station to be received and output and an output signal of an adjacent slave station is within a certain range. .

[0002]

2. Description of the Related Art Conventionally, in this type of transmission system,
When each of the slave digital transmission devices receives and outputs the NNI signal transmitted from the master station and corrects the delay of the output signal, a VC (Virtual Container) contained in the payload of the NNI signal is used. 3 or VC-4, the memory for multiple frames constituting the VC is provided in each slave station to delay-delay the output signal.

[0003]

In a conventional transmission system, when delaying the output signal of each slave station, it is necessary to provide a memory for multiple frames in each slave station as described above, which increases the circuit scale. There were drawbacks. Therefore, the present invention provides a transmission system in which each station, which is a digital transmission device, is connected to a transmission line in a ring shape, when an output signal of each slave station that receives and outputs an NNI signal output from a master station is corrected. An object of the present invention is to perform delay correction within a certain delay range without increasing the circuit scale.

[0004]

SUMMARY OF THE INVENTION In order to solve such a problem, the present invention provides an NN of an SDH network formed in a ring shape.
Each station consisting of a master station and a plurality of slave stations is connected to a transmission line on which the I signal is transmitted, and each output signal between adjacent slave stations receiving and outputting an NNI signal transmitted from the master station to each slave station. An output signal delay correction method for a transmission system for correcting a delay in a fixed delay range, wherein each of the slave stations has an NNI frame detecting section for detecting a frame position of an NNI signal;
A multi-frame detection unit that detects a multi-frame position from a path overhead of a VC of the I signal, a reference signal generation unit that generates a reference signal from an NNI frame from the NNI frame detection unit and a multi-frame from the multi-frame detection unit, An output signal correction unit for correcting the phase of the output signal based on the reference signal is provided, and each of the adjacent slave stations performs delay correction of the output signal using the same reference signal. Therefore, when delay correction is performed on output signals of adjacent slave stations, delay correction can be performed within a fixed delay range without increasing the circuit scale. In addition, the above-mentioned reference signal generation unit is a first reference signal generation unit, a multi-frame generation unit for generating a multi-frame from a signal passed through the multi-frame detection unit, and an NNI frame from an output signal of the multi-frame generation unit. And a second reference for generating a reference signal based on the NNI frame from the NNI frame generator and the multi-frame from the multi-frame generator, for generating an NNI signal to an adjacent slave station or master station as an NNI signal. A signal generation unit is provided at each slave station, and at each adjacent slave station, NN
When the I signal is received, the output signal is delay-corrected based on the reference signal of the second reference signal generator, and when the NNI signal is received from the downstream side of the transmission path, the reference of the first reference signal generator is used. The delay correction of the output signal is performed based on the signal.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a transmission system to which the present invention is applied. In this figure, this transmission system includes a master station 1 as each digital transmission device.
And a plurality of slave stations 2 ₁ , 2 _n , 2 _{n + 1} , 2 _m . The master station 1 and each of the slave stations 2 are connected in a ring shape via a transmission path, and NNI signals of the SDH network are transmitted between the stations via the transmission path. Here, the transmission path, the route from the master station 1 slave station 2 ₁ through to slave station 2 _n, slave station 2 _{n + 1,} the route through which NNI signal path direction leading to the slave station 2 _m (i.e., from the upstream to the downstream ) and the root, slave station 2 _{n + 1} through the slave stations 2 _m from the main station 1, the slave station 2 _n, the route through which NNI signal path orientation leading to slave station 2 ₁ (i.e., the route from the downstream to the upstream) to route And The input data to the master station 1 is A1, and the output data from the slave stations 2 _n and 2 _{n + 1} is B1 and B2, respectively.

Next, FIG. 2 is a block diagram of the slave station 2 constituting the transmission system. In the figure, a slave station 2 is input via a route and a route, and
A multi-frame generation unit 2 for individually generating a multi-frame for each NNI signal input via the I-frame detection units 27 and 31 and the multi-frame detection units 28 and 30
NNI frame generators 25 and 21 which generate NNI frames for the signals passing through the respective multi-frame generators 24 and 22 and output the respective NNI signals as root NNI signals to adjacent slave stations. , NNI frame detectors 27 and 31 for detecting the frame position of the input NNI signal, multiframe detectors 28 and 30 for detecting the position of the multiframe from the path overhead of the VC of the NNI signal, reference signal generator 23, 26,
29, 32, a selector 33, a data extractor 34, an output data corrector 35, and a reference signal selector 36.

In FIG. 2, an NNI signal from a route is transmitted to an NNI frame detecting section 27 and a multi-frame detecting section 2.
The program enters the selection section 33 through the section 8. This NNI signal is also output to the multi-frame generation unit 24,
The signal is output as a route NNI signal to the adjacent slave station via the frame generation unit 25. On the other hand, N
The NI signal is also transmitted to the NNI frame detector
1 and enters the selection unit 33 via the multi-frame detection unit 30. The NNI signal is output to the multi-frame generation unit 22.
And output to the adjacent slave station via the NNI frame generation unit 21 as a root NNI signal.

The selecting section 33 selects one of the routes or the routes according to the state of the transmission path of each route, and outputs the NNI signal of the selected route to the data extracting section 3.
4 is output. The data extraction unit 34 extracts output data from the VC in the NNI signal and outputs it to the output data correction unit 35.

Here, the reference signal generator 23 generates a reference signal from the NNI frame signal of the NNI frame generator 21 and the multi-frame signal of the multi-frame generator 22, and outputs the reference signal to the reference signal selector 36. Further, the reference signal generation unit 26 generates a reference signal from the NNI frame signal of the NNI frame generation unit 25 and the multi-frame signal of the multi-frame generation unit 24, and outputs the reference signal to the reference signal selection unit 36. The reference signal generation unit 29 generates a reference signal from the NNI frame signal from the NNI frame detection unit 27 and the multi-frame signal from the multi-frame detection unit 28, and outputs the reference signal to the reference signal selection unit 36. The reference signal generation unit 32 generates a reference signal from the NNI frame signal from the NNI frame detection unit 31 and the multi-frame signal from the multi-frame detection unit 30, and
Output to 6.

Each of the reference signal generators 23, 26, 29, 32
The reference signal selection unit 36 that has received the respective reference signals from the input unit selects the selected reference signal according to selection conditions described later and outputs the selected signal to the output data correction unit 35. That is, the selection condition of the reference signal is different in adjacent example slave station 2 _n and slave station 2 _{n + 1} and,
In the slave station 2 _n , when the selection unit 33 selects the root NNI signal, the selection unit 33 selects the reference signal from the reference signal generation unit 26, and when the selection unit 33 selects the root NNI signal, the selection unit 33 selects the reference NNI signal. The reference signal from the signal generator 32 is selected. On the other hand, in the slave station 2 _{n + 1} , when the selection unit 33 selects the root NNI signal, the selection unit 33 selects the reference signal from the reference signal generation unit 29 and the selection unit 33 selects the root NNI signal. If there is, the reference signal from the reference signal generator 23 is selected.

The output data correction section 35 corrects the output phase in accordance with the output data of the data extraction section 34 in accordance with the reference signal selected by the reference signal selection section 36 and outputs it as output data B. FIG. 4 is a timing chart showing the phase correction status of the output signal of each slave station. Here, FIG.
Is a reference signal that matches the route signal,
The signal in FIG. 4B is a reference signal that matches the route signal. That is, when the slave station 2 has selected the route, the output phase is adjusted to the reference signal of the route in FIG. 4A, and the output signal from the data extraction unit 34 shown in FIG. Output as an output signal as shown in d). When the slave station 2 has selected a route, the output phase is adjusted to the reference signal of the route in FIG. 4B, and the output signal from the data extraction unit 34 shown in FIG.
Output as an output signal as shown in (e).

FIG. 3 is a block diagram of the master station 1 constituting the transmission system.
1, 14, multi-frame generators 12 and 13, distributor 15, and data storage 16. In master station 1,
The input data A is stored in the VC by the data storage unit 16. The distribution unit 15 distributes this data to the multi-frame generation units 12 and 13. The data distributed to each of the multi-frame generation units 12 and 13 is
Through the I-frame generating units 11 and 14, one is used as the root NNI frame data, and the other is used as the root NN frame data.
Output as I frame data in two directions: route.

[0013] Therefore, if the data through the route is partitioned between slave station 2 _n and slave station 2 _{n + 1} adjacent, as described above, the phase reference signal from the slave station 2 _n in the reference signal generator 26 In addition, the slave station 2 _{n + 1} outputs the data in phase with the reference signal from the reference signal generator 29. Here, the reference signal generator 26 of the slave station 2 _n
From the reference signal from the reference signal generator 29 of the slave station 2 _{n + 1} , the difference between the two slave stations 2 _n and 2 _{n + 1}
Since they are adjacent to each other, they are shifted only by the delay of the transmission path between the slave station 2 _n and the slave station 2 _{n + 1} . Accordingly, the phase difference between the output data of the slave station 2 _n and slave station 2 _{n + 1} slave station 2 _n and slave station 2
It can be suppressed within the transmission path delay between _{n + 1} . Also, if the data through the route is partitioned between slave station 2 _{n + 1} and the slave station 2 _n adjacent, as described above, the slave station 2
_{In n + 1} , data is output in phase with the reference signal from the reference signal generation unit 23, and in the slave station 2 _n , the reference signal generation unit 3
The data is output in phase with the reference signal from the second.

The data is transmitted from the master station 1 to the slave station 2 to which data is adjacent.
If it distributed to _n and slave station 2 _{n + 1} and, slave station 2, _n and slave station 2 _{n + 1,} in the case of root NNI frame detecting section 2
7 and a reference signal from a reference signal generation unit 29 generated based on each detection frame from the multi-frame detection unit 28, and outputs data in phase. In the case of a route, an NNI frame detection unit 31 and a multi-frame detection Part 3
It is also possible to configure so as to output data in phase with the reference signal from the reference signal generation unit 32 generated based on each detection frame from 0.

As described above, in each of the adjacent slave stations connected in a ring on the transmission path, the phase correction of the output data is performed based on the reference signal generated from the NNI frame and the multi-frame, so that the adjacent slave stations can perform the phase correction. In each of the slave stations, the phase difference between the output data can be suppressed within a certain delay. In this case, it is not necessary to secure a memory for multiple frames in each slave station, so that delay correction can be performed without increasing the circuit scale.

[0016]

As described above, according to the present invention, each slave station has an NNI frame detector for detecting the frame position of the NNI signal received from the master station, and the multi-frame position based on the VC path overhead of the NNI signal. A reference signal generation unit that generates a reference signal based on the NNI frame from the NNI frame detection unit and the multiframe from the multiframe detection unit;
An output signal correction unit that corrects the phase of the output signal based on the reference signal is provided, and in each of the adjacent slave stations, delay correction of the output signal is performed by the same reference signal. In the case of delay correction, the delay can be corrected within a certain delay range without increasing the circuit scale. A multi-frame generation unit configured to generate the multi-frame from a signal transmitted through the multi-frame detection unit, while using the reference signal generation unit as a first reference signal generation unit;
An NNI frame generator for generating an NNI frame from the output signal of the multiframe generator and transmitting the NNI frame to an adjacent slave or master station as an NNI signal; an NNI frame from the NNI frame generator and a multiframe from the multiframe generator And a second reference signal generation unit for generating a reference signal by each of the slave stations.
When the NNI signal is received from the upstream side of the transmission line, the output signal is delay-corrected based on the reference signal of the second reference signal generation unit, and when the NNI signal is received from the downstream side of the transmission line, the first signal is received. Since the output signal is delay-corrected based on the reference signal of the reference signal generator, the delay difference between the output signals output from each slave station is used to transmit data to a transmission path connecting the two slave stations. It can be suppressed within a time corresponding to the data delay time.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a transmission system to which the present invention has been applied.

FIG. 2 is a block diagram of a slave station constituting the system.

FIG. 3 is a block diagram of a main station constituting the system.

FIG. 4 is a timing chart showing a state of delay correction of an output signal of a slave station.

[Explanation of symbols]

1 ... master station, 2, 2 ₁ , 2 _n , 2 _{n + 1} , 2 _m ... slave station, 1
1, 14, 21, 25... NNI frame generator, 12,
13, 22, 24: Multi-frame generation unit, 15: Distribution unit, 27, 31: NNI frame detection unit, 28, 30 ...
Multi-frame detectors, 23, 26, 29, 32 ... reference signal generators, 33 ... selectors, 34 ... data extractors, 35
... an output data correction unit, 36 ... a reference signal selection unit.

Claims (2)

[Claims] An NN transmitted from a master station to each slave station is connected to each of a master station and a plurality of slave stations connected to a transmission line for transmitting NNI signals of an SDH network formed in a ring shape.
An output signal delay correction method for a transmission system for delay-correcting each output signal between adjacent slave stations receiving and outputting an I signal within a predetermined delay range, wherein each slave station detects a frame position of an NNI signal. N
An NI frame detector, a multi-frame detector for detecting a multi-frame position from a VC path overhead of the NNI signal, and a reference signal are generated from the NNI frame from the NNI frame detector and the multi-frame from the multi-frame detector. A reference signal generation unit and an output signal correction unit for correcting the phase of the output signal based on the reference signal are provided, and adjacent slave stations perform delay correction of the output signal using the same reference signal. Output signal delay correction method of the transmission system. 2. The multi-frame generation unit according to claim 1, wherein the reference signal generation unit is a first reference signal generation unit, and a multi-frame generation unit generates a multi-frame from a signal passed through the multi-frame detection unit. NNI frame generated from the output signal of NNI and transmitted as an NNI signal to an adjacent slave station or master station.
A frame generation unit and an NNI from the NNI frame generation unit
A second reference signal generation unit that generates a reference signal based on a frame and a multiframe from the multiframe generation unit is provided in each slave station. When each adjacent slave station receives an NNI signal from the upstream side of the transmission path, The output signal is delay-corrected based on the reference signal of the second reference signal generator, and the first signal is received when the NNI signal is received from the downstream side of the transmission path.
A delay correction for an output signal based on a reference signal of the reference signal generation unit.