JP3546347B2 - Line connection method and line connection device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a technique for connecting a high-speed digital dedicated line to ISDN subscriber lines of a plurality of primary group interfaces including [23B + D] and [24B].
[0002]
[Prior art]
The subscriber line of the primary interface [23B + D] represented by the ISDN primary rate has 23 information channels (B channels) per cable, and one subscriber can exchange and connect to a large number of terminals. , PBX are effective.
[0003]
Also, when installing a PBX of 23 channels or more, it is necessary to cope by pulling in a plurality of ISDN subscriber lines. In such a case where a plurality of subscriber lines are pulled into the same place, One of them is a [23B + D] subscriber line, the other is a [24B] subscriber line having 24 B channels, and the [23B + D] subscriber line control channel (D channel) is [24B]. Has also been realized.
[0004]
However, in an area where a subscriber line of the ISDN primary rate ISDN is not installed, such a service cannot be received.
[0005]
In order to solve this problem, it is conceivable to extend a plurality of ISDN primary rate subscriber lines by using a high-speed digital dedicated line composed of a metal line.
[0006]
However, there is a difference between the transmission rate and the number of bits per frame between the subscriber line of the primary interface and the high-speed digital dedicated line.
[0007]
That is, in the ISDN primary rate line, as shown in (a) of FIG. 15, a multi-frame is placed at the head of 23 B channels B1 to B23 in units of 8 bits and one D channel or 24 B channels B1 to B24. One frame is formed by adding a 1-bit frame bit f multiplexed with a synchronization pattern, a CMB check bit, and control bits (referred to as m bits) for performing fault isolation, and the like, and one frame is formed. , 1.544 Mbps.
[0008]
On the other hand, as shown in FIG. 15B, the high-speed digital leased line forms one frame with 24 time slots TS1 to TS24 in units of 8 bits, and 125 μs per frame, that is, 1.536 Mbps. Transmitting at data rate.
[0009]
Therefore, even if data of the primary rate of the ISDN is simply relayed to the dedicated line, one bit of data cannot be transmitted per frame.
[0010]
For this purpose, a method of transmitting only 192 bits of data from the ISDN primary rate frame excluding the frame bit f to the dedicated line side, or using one time slot of each dedicated line as a dedicated slot for frame bit transmission A method is conceivable.
[0011]
[Problems to be solved by the invention]
However, in the method of transmitting only 192 bits of data excluding the frame bit f from the frame of the ISDN primary rate, the control bits multiplexed in the frame bits cannot be used. When the error occurs, the loopback test control signal is not transmitted, so that separation cannot be performed and code error monitoring cannot be performed.
[0012]
Also, if one time slot of each dedicated line is used as a dedicated slot for frame bit transmission, data for one channel cannot be transmitted for each subscriber line, and the function of the ISDN primary rate is limited, and This is inconvenient when PBX is used as an example.
[0013]
An object of the present invention is to provide a line connection method and a line connection device that solve such a problem. The present invention focuses on the fact that the information transfer amount of the control channel D of the [23B + D] subscriber line of ISDN is relatively small, and there is a steady margin at a data rate of 64 kbs. Is solved.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, a line connection method according to claim 1 of the present invention comprises:
One [23B + D] subscriber line of ISDN (2 ₁ ) And [24B] subscriber lines (2 _Two ~ 2 ₉ ), And a plurality of high-speed digital dedicated lines (11) corresponding to the number of the subscriber lines. ₁ ~ 11 ₉ ), The line connection method for connecting
Extracting D-channel data at a predetermined rate included in the signal input from the [23B + D] subscriber line and frame bits included in the signal input from each of the subscriber lines;
Storing the extracted D-channel data;
The stored D-channel data is read out at a rate of 7/8 of the predetermined rate, and multiplexed so as to include at least m-bit information of each subscriber line based on the extracted frame bits of each subscriber line. Generating multiplexed frame bits at a rate of 1/8 of said predetermined rate;
Multiplexing the read D channel data and the generated multiplexed frame bits;
Inserting the multiplexed multiplexed data of the predetermined rate into a specific time slot of a high-speed digital leased line corresponding to the [23B + D] subscriber line;
Extracting multiplexed data inserted at the predetermined rate into the specific time slot of a signal input from the high-speed digital dedicated line corresponding to the [23B + D] subscriber line;
Separating the extracted multiplexed data into 7-bit D-channel data and 1-bit frame bits;
Storing the separated D-channel data;
Distributing the separated frame bits for each of the subscriber lines;
Reading the accumulated D-channel data at the predetermined speed;
Generating frame bits to be output to each of the subscriber lines from the allocated frame bits at a rate of 1/8 of the predetermined rate;
Outputting the D channel data read at the predetermined speed to the [23B + D] subscriber line, and outputting the frame bits generated at a speed 1/8 of the predetermined speed to each subscriber line; It is characterized by including.
[0015]
Further, the line connection device according to claim 2 of the present invention,
One [23B + D] subscriber line of ISDN (2 ₁ ) And [24B] subscriber lines (2 _Two ~ 2 ₉ ), And a plurality of high-speed digital dedicated lines (11) corresponding to the number of the subscriber lines. ₁ ~ 11 ₉ ) In the line connection device for connecting
D channel data extracting means (22) for receiving a signal input from the [23B + D] subscriber line and extracting D channel data at a predetermined speed from the signal;
A plurality of frame bit extracting means (22, 25) for respectively receiving signals input from the respective subscriber lines and extracting frame bits from the signals;
A first buffer (32);
First data writing means (31) for storing the D channel data extracted by the D channel data extraction means in the first buffer;
First data reading means (33) for reading the D-channel data stored in the first buffer at a rate of 7/8 of the predetermined rate;
Based on the frame bits of each subscriber line extracted by the plurality of frame bit extracting means, multiplexed frame bits multiplexed so as to include at least m-bit information of each subscriber line are set to 1 at the predetermined rate. Frame bit multiplex generation means (35) for generating at a rate of / 8;
Multiplexing means (36) for multiplexing the data output from the first data reading means and the multiplexed frame bits generated by the frame bit multiplexing generation means into the data of the predetermined speed;
The multiplexed data multiplexed by the multiplexing means is inserted into a specific time slot of a high-speed digital leased line corresponding to the [23B + D] subscriber line, and is transmitted to the high-speed digital leased line. Means (23);
Multiplexed data extracting means for receiving a signal from a high-speed digital dedicated line corresponding to the [23B + D] subscriber line and extracting multiplexed data inserted into the specific time slot at the predetermined speed from the signal. 23)
Separating means (38) for separating the multiplexed data extracted by the multiplexed data extracting means into 7-bit D-channel data and 1-bit frame bits;
A second buffer (40);
Second data writing means (39) for accumulating D-channel data at a speed of 7/8 of the predetermined speed separated by the separation means in the second buffer;
Second data reading means (41) for reading the D channel data stored in the second buffer at the predetermined speed;
D channel data transmitting means (22) for transmitting the D channel data output from the second data reading means to the [23B + D] subscriber line;
Frame bit distribution means (43) for distributing the frame bits separated by the separation means for each of the subscriber lines;
A plurality of frame bit generating means (28) for respectively receiving the frame bits allocated by the frame bit allocation means and generating frame bits to be output to each of the subscriber lines at a rate of 1/8 of the predetermined rate; , 44),
A plurality of frame bit transmitting means (22, 25) for transmitting the frame bits respectively generated by the plurality of frame bit generating means to each of the subscriber lines.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a plurality of subscribers forming one set of one [23B + D] subscriber line and eight [24B] subscriber lines of ISDN by using two line connection apparatuses of the present invention. FIG. 1 shows an overall view of a system in which a line is extended by a high-speed digital exclusive line.
[0017]
In FIG. 1, two line connection devices 20, 20 are the same, and one line connection device 20 has nine subscriber lines 2 connected to an ISDN exchange 1. ₁ ~ 2 ₉ And 9 dedicated lines 11 of the dedicated line network ₁ ~ 11 ₉ And the other line connection device 20 is a DSU 3 of ISDN. ₁ ~ 3 ₉ Subscriber lines 2 respectively connected to ₁ '~ 2 ₉ ′ And each of the dedicated lines 11 ₁ ~ 11 ₉ Dedicated line 11 corresponding to each ₁ '~ 11 ₉ ′.
[0018]
In this system, signals from the exchange 1 are transmitted by two line connection devices 20 via a dedicated line network to each DSU 3. ₁ ~ 3 ₉ , And a signal from the DSU side is transmitted to the exchange 1 via a dedicated line network. Note that DSU3 ₁ ~ 3 ₉ Are connected to PBX4.
[0019]
Here, subscriber line 2 ₁ ~ 2 ₉ , 2 ₁ '~ 2 ₉ ′, Subscriber line 2 ₁ , 2 ₁ 'Is the subscriber line of [23B + D], and the subscriber line 2 _Two ~ 2 ₉ , 2 _Two '~ 2 ₉ 'Is the subscriber line of [24B].
[0020]
Next, the line connection device 20 will be described. Since the two line connection devices are the same as described above, the line connection device on the exchange side will be mainly described.
[0021]
The line connection device 20 has nine subscriber lines 2 as shown in FIG. ₁ ~ 2 ₉ Each dedicated line 11 ₁ ~ 11 ₉ 9 line connection units 21 to connect to ₁ ~ 21 ₉ It has.
[0022]
Line connection unit 21 ₁ Is the subscriber line 2 of [23B + D] ₁ And dedicated line 11 ₁ The connection is made up of a subscriber line interface 22, a dedicated line interface 23, and a demultiplexing processing unit 30.
[0023]
The subscriber line interface 22 is connected from the exchange 1 to the subscriber line 2. ₁ Is converted into an electric signal, and a 1-bit frame bit f _u1 And 23 8-bit B-channel data B1 to B23 and 8-bit D-channel data Da and output them to the demultiplexing processing unit 30. The data multiplexed into 23B + D output from the demultiplexing processing unit 30 and the frame bit f _d1 , A signal of one frame is converted into an optical signal, and ₁ Output to
[0024]
The dedicated line interface 23 is a dedicated line 11 ₁ The 8-bit data of each of the time slots TS1 to TS24 input through the CPU is extracted, and the data of each of the extracted time slots TS1 to TS23 is multiplexed with B channel data, and the data of the time slot TS24 is multiplexed with D channel data and frame bits. The data is output to the demultiplexing processing unit 30 as divided data. Also, the data multiplexed by the demultiplexing processing unit 30 is inserted into the time slots TS1 to TS24 to form a signal of one frame, and ₁ Output to the side.
[0025]
Although the details will be described later, the demultiplexing processing unit 30 converts the D-channel data Da extracted by the subscriber line interface 22 into 7-bit units, and converts the 7-bit D-channel data into each subscriber line 2. ₁ ~ 2 ₉ Frame bit f input from _u1 ~ F _u9 Are combined into 8 bits, multiplexed with the B channel data B1 to B23, and output to the dedicated line interface 23.
[0026]
The demultiplexing processing unit 30 separates the data of the time slot TS24 separated by the dedicated line interface 23 into 7-bit D-channel data and 1-bit frame bits, and divides the D-channel data into 8-bit units. Each data of the time slots TS1 to TS23 is multiplexed with 23B + D and output to the subscriber line interface 22. ₁ ~ 2 ₉ And this subscriber line 2 ₁ Is generated and output to the subscriber line interface 22.
[0027]
On the other hand, the other line connection unit 21 _Two ~ 21 ₉ Is the 8 subscriber lines 2 of [24B] _Two ~ 2 ₉ And 8 dedicated lines 11 _Two ~ 11 ₉ And a dedicated line interface 26, a dedicated line interface 26, a frame bit buffer 27, and a frame bit generating means 28.
[0028]
Each subscriber line interface 25 is connected from the exchange 1 to the subscriber line 2. _Two ~ 2 ₉ Is converted into an electric signal, and a 1-bit frame bit f _u2 ~ F _u9 And 24 pieces of B channel data B1 to B24 are extracted, the extracted frame bits are stored in the respective frame bit buffers 27, and the extracted B channel data B1 to B24 are output to the respective dedicated line interfaces 26. . Also, the B channel data B1 to B24 from the dedicated line interface 26 and the frame bit f output from the frame bit generation means 28 _d2 ~ F _d9 , Each of which constitutes one frame signal, converts it into an optical signal, and _Two ~ 2 ₉ Output to
[0029]
Each dedicated line interface 26 forms one frame by inserting B channel data B1 to B24 from the subscriber line interface 25 into the time slots TS1 to TS24, respectively. _Two ~ 11 ₉ Output to each dedicated line 11 _Two ~ 11 ₉ , And extracts the 8-bit data of the time slots TS1 to TS24 input through the interface and outputs them to the subscriber interface 25 as B channel data B1 to B24.
[0030]
Each frame bit buffer 27 stores the stored frame bit f _u2 ~ F _u9 To the line connection unit 21 ₁ Is output to the demultiplexing unit 30.
[0031]
Each of the frame bit generation means 28 includes the B channel data B1 to B24 extracted by the dedicated line interface 26 and the line connection unit 21. ₁ Frame bit f from the demultiplexing processor 30 _c2 ~ F _c9 Based on each subscriber line 2 _Two ~ 2 ₉ Frame bits f added to the data to be output to _d2 ~ F _d9 Are generated and output to the respective subscriber line interfaces 25.
[0032]
Next, the line connection unit 21 ₁ The demultiplexing processing section 30 will be described in detail with reference to FIG.
[0033]
As shown in FIG. 3, the D channel data Da output from the subscriber line interface 22 is input to the first data writing means 31. The first data writing means 31 removes the idle flag Fi from the D channel data Da and writes only the data Db to be transmitted to the first buffer 32.
[0034]
The idle flag Fi is an 8-bit specific flag that the ISDN interface continuously transmits on the D channel in an idle state where there is no data to be transmitted.
[0035]
The data Db stored in the first buffer 32 is sequentially read out at a speed of 56 kbps by the first data reading means 33, and is output to a first multiplexing means 36 described later. While there is no data to be read in the first buffer 32, the first data reading means 33 outputs an idle flag Fi to the first multiplexing means 36 at a rate of 56 kbps instead of the data.
[0036]
The frame bit buffer 34 outputs the frame bits f output from the subscriber line interface 22 bit by bit. _u1 Are sequentially stored.
[0037]
The frame bit multiplex generation means 35 outputs the frame bit f stored in the frame bit buffer 34. _u1 And other line connection unit 21 _Two ~ 21 ₉ Frame bit f stored in the frame bit buffer 27 of _u2 ~ F _u9 In addition to the 6-bit multi-frame synchronization pattern (F1 to F6) and the 6-bit CMB check bit for error checking, all subscriber lines 2 ₁ ~ 2 ₉ A multiplexed frame bit fa is generated by multiplexing information called m bits, which are allotted for maintenance, monitoring and test control of 12 bits, and output to the first multiplexing means 36 at a rate of 8 kbps.
[0038]
Here, in order to understand the operation of the frame bit multiplex generation means 35, the details of the frame bits of the ISDN line will be described.
[0039]
As shown in FIGS. 3A to 3C, the 1-bit frame bit added to the head of the frame data output from the DSU side of the ISDN to the switchboard includes a 6-bit multi-frame synchronization pattern F1. ... F6, 6-bit CMB check bits e1 to e6, and 12-bit m-bit information M1 to M12 for maintenance / monitoring and test control.
[0040]
Also, the 1-bit frame bits added to the head of the frame data from the ISDN exchange have the same 6-bit multi-frame synchronization patterns F1 to F6 and 6 bits as shown in FIGS. CMB check bits e1 to e6 and 12-bit m-bit information M1 to M12 for maintenance / monitoring and test control shown in FIG. 3 (d). (E) are added one bit at a time to one frame in the order shown in (e).
[0041]
Here, since the total of the multi-frame synchronization patterns F1 to F6, the CMB check bits e1 to e6, and the m-bit information M1 to M12 is 24 bits, all frame bits are transmitted in 24 frames. The multi-frame synchronization patterns F1 to F6 included in the 24 bits are for detecting which frame is the head of the 24 frames. Further, “0” in the m-bit information of (c) and (d) in FIG. 3 is an unused bit.
[0042]
Also, a set of nine subscriber lines 2 ₁ ~ 2 ₉ Data in any of the above directions is synchronized in units of 24 frames, and the multi-frame synchronization patterns F1 to F6 are common to each subscriber line.
[0043]
The CMB check bits e1 to e6 are always newly generated for each line when data is relayed and output.
[0044]
Therefore, assuming that 24 frames are 1 multi-frame, 9 subscriber lines 2 ₁ ~ 2 ₉ In order to output all the m-bit information to the dedicated line side, it is sufficient that 9 multi-frames are required.
[0045]
The frame bit multiplex generation means 35 multiplexes the m-bit information of each subscriber line in a predetermined order, and, for example, so as to identify which subscriber line corresponds to the m-bit information, Subscriber line 2 ₁ When generating and outputting the frame bits of "1", "1" data indicating that this multiframe is the head of 9 multiframes is inserted into predetermined unused bits (for example, M1) of the m-bit information. , The data at the predetermined position is kept at “0” for the 8 multi-frames following.
[0046]
The first multiplexing means 36 multiplexes the 56 kbps data Dc output from the first data reading means 33 and the frame bit fa output at 8 kbps from the frame bit multiplex generation 35 into 64 kbps data. The multiplexed multiplexed data Dd is input to the second multiplexing means 37.
[0047]
The second multiplexing means 37 multiplexes the multiplexed data Dd output from the first multiplexing means 36 with the B channel data B1 to B23 output from the subscriber line interface 22, and outputs the multiplexed data to the dedicated line interface 23. I do.
[0048]
On the other hand, the separating means 38 separates 7-bit D channel data Df and 1-bit frame bit fb from the multiplexed data De output from the dedicated line interface 23. The speed of the D channel data Df is 56 kbps, and the speed of the frame bit fb is 8 kbps.
[0049]
The D channel data Df output from the separating means 38 is input to the second data writing means 39. The second data writing unit 39 removes the idle flag Fi from the D channel data Df output from the separation unit 38, and writes only the data to be transmitted to the second buffer 40.
[0050]
The data Dg stored in the second buffer 40 is sequentially read out at a rate of 64 kbps by 8 bits at a time at a rate of 64 kbps and input to the third multiplexing means 42. The data is multiplexed with the channel data B1 to B23 and output to the subscriber line interface 22. Here, while there is no data to be read in the second buffer 40, the second data reading means 41 outputs an 8-bit idle flag Fi to the third multiplexing means 42 at a speed of 64 kbps instead of the data. I do.
[0051]
The frame bit distribution means 43 receives the frame bits fb separated by the separation means 38, detects the first multiframe of the nine multiframes, and follows the subscriber line according to the multiplexing order by the frame bit multiplex generation means 35. 2 ₁ ~ 2 ₉ Each frame bit f _c1 ~ F _c9 To each line connection unit 2 ₁ ~ 2 ₉ Is output to the frame bit generation means 44 and 28.
[0052]
The frame bit generation means 44 outputs the frame bit f output from the frame bit distribution means 43. _c1 Subscriber line 2 based on ₁ Frame bit f for output to _d1 And outputs this to the subscriber line interface 22 at a rate of 8 kbps.
[0053]
Further, the frame bit generating means 44 performs a predetermined operation on the output of the third multiplexing means 42 to newly generate a bit for error checking, and outputs the bit to the subscriber line interface 22.
[0054]
Next, the operation of the line connection device 20 will be described. ₁ ~ 21 ₉ , Each is separated by a subscriber line interface 22, 25 and a dedicated line interface 23, 26. ₁ Is transmitted bidirectionally without special processing being performed only by the multiplexing processing by the second and third multiplexing means 37 and 42. ₁ D channel data and each subscriber line 2 ₁ ~ 2 ₉ Will be described.
[0055]
First, a case where data is transmitted from the subscriber line to the dedicated line will be described.
[23B + D] subscriber line 2 ₁ To line connection unit 21 ₁ , D-channel data Da1, Da2,... Including a plurality of idle flags Fi are input, for example, as shown in FIG. Where d _ij Is bit data of each D channel data.
[0056]
In addition, each subscriber line 2 ₁ From the frame bit f along with the D channel data as shown in FIG. _u1 1, f _u1 , Are sequentially input and stored in the frame bit buffer 34.
[0057]
Also, subscriber line 2 of [24B] _Two ~ 2 ₉ As shown in FIG. 5C, the frame bits f _u2 1, f _u2 2, ..., f _u3 1, f _u3 2, ..., f _u9 1, f _u9 Are input to each line connection unit 21. _Two ~ 21 ₉ , Respectively.
[0058]
Line connection unit 21 ₁ Are input to the first buffer 32 as shown in FIG. 6 as data Db1, Db2,... From which the idle flag Fi has been removed by the first data writing means 31. It is.
[0059]
The data written in the first buffer 32 is sequentially read out by the first data reading means 33 at a speed of 56 kbps, which is 7/8 of 64 kbps. However, if there is no more data during reading, the idle flag Fi is inserted. The data Dc1, Dc2,... Shown in FIG. 7A are output to the first multiplexing means 36 at a speed of 56 kbps. Here, the data Dc1, Dc2,... Are data of 7 bits since the read speed is 56 kbps, which is ／ of 64 kbps.
[0060]
On the other hand, as shown in FIG. 7 (b), the frame bit multiplex generation 35 performs the reading of the data Dc1, Dc2,. ₁ ~ 2 ₉ Multiplexed frame bits fa1, fa2,... Multiplexed based on the frame bits stored in the frame bit buffers 34, 27 at a rate of 8 kbps.
[0061]
Here, as shown in FIG. 8, for example, the 24-bit multiplexed frame bits fa1 to fa24 output by the frame bit multiplexing generator 35 in the first multiframe correspond to the subscriber line 2 ₁ Synchronization lines F1 to F6 input from the controller and the dedicated line 11 in the previous multiframe. ₁ The CMB check bits e1 to e6 obtained by performing a predetermined operation on the data transmitted to the mobile station make up 12 bits. ₁ Bit information M1 input from ₁ ~ M12 ₁ Constitutes 12 bits. It should be noted that among the m-bit information of this first multi-frame, ₁ "1" indicating that this multi-frame is the head of the nine multi-frames is inserted into.
[0062]
The 24-bit multiplexed frame bits fa25 to fa48, fa49 to fa72,..., Fa193 to fa216 output by the frame bit multiplexing generator 35 in the second to ninth multiframes are the same as those of the subscriber line 2 in the same manner as described above. ₁ Multi-frame synchronization patterns F1 to F6 and the dedicated line 11 in the previous multi-frame ₁ 12 bits are configured by CMB check bits e1 to e6 for the data output to _Two ~ 2 ₉ M-bit information M1 _Two ~ M12 _Two , M1 _Three ~ M12 _Three , ..., M1 ₉ ~ M12 ₉ Constitutes 12 bits. Note that M1 of the m-bit information of the second to ninth multiframes _Two ~ M1 ₉ Are left at "0" to indicate that these multiframes are not the head of the nine multiframes.
[0063]
As shown in FIG. 9, the first multiplexing means 36 adds data Dc1, Dc2,... To the multiplexed frame bits fa1, fa2,. The 8-bit multiplexed data Dd1, Dd2,... Are input to the second multiplexing means 37, multiplexed with B-channel data, and output to the dedicated line interface 23.
[0064]
The data multiplexed by the second multiplexing means 37 is transmitted to the dedicated line 11 by the dedicated line interface 22. ₁ Of the dedicated line 11 ₁ Is output to Here, for example, the B channel data B1 to B23 are inserted into the time slots TS1 to TS23, and the multiplexed data Dd is inserted into the time slot TS24 and ₁ Is output to
[0065]
Since the transmission speeds of the B channel data B1 to B23 and the multiplexed data Dd multiplexed by the second multiplexing means 37 are each 64 kbps, the dedicated line 11 ₁ Is 1.536 Mbps (= 64k × 24), which matches the data rate of the 1.5M logical path of the dedicated line.
[0066]
On the other hand, the other line connection unit 21 _Two ~ 21 ₉ Then, subscriber line 2 _Two ~ 2 ₉ ~ Frame bit f from input data _u2 ~ F _u9 Is removed and only the 24 B channel data is output to the dedicated line interface 26. The B channel data B1 to B24 are inserted into the 24 time slots TS1 to TS24, respectively, and _Two ~ 11 ₉ Output to Therefore, the dedicated line 11 of this line connection device 20 _Two ~ 11 ₉ Is also equal to the data rate of the 1.5M logical path of the dedicated line.
[0067]
Next, a case where data is transmitted from the dedicated line side to the subscriber line side will be described.
Dedicated line 11 from one line connection device ₁ Are input via the demultiplexer 38, the 7-bit data Df1, Df2,... Shown in FIG. 11A and the multiplexed data De1, De2,. Are separated into 1-bit frame bits fb1, fb2,...
[0068]
The data Dg1, Dg2,... From which the idle flags have been removed from the data Df1, Df2,... Are written to the second buffer 40 by the second data writing means 39 as shown in FIG.
[0069]
The data Dg1, Dg2,... Written in the second buffer 40 are sequentially read out at a speed of 64 kbps by the second data reading means 41. When there is no more data to be read, the idle flag Fi is inserted. 13, D-channel data Dh1, Dh2,... In 8-bit units are output to the multiplexing means 42, and the D-channel data Dh and the B-channel data from the dedicated line interface 23 are multiplexed. The output data is output to the subscriber line interface 21.
[0070]
Further, the frame bit distribution unit 43 receiving the frame bits fb1, fb2,... From the separation unit 38 detects the multiframe in which the data of M1 of the m-bit information is “1” as the first multiframe.
[0071]
Here, assuming that the frame bit fb1 is the first frame bit of the first multiframe, the frame bit distribution unit 43 sets the frame bits fb1 to fb24 in the first multiframe to the subscriber line 2 as shown in FIG. ₁ Frame bit f corresponding to _c1 And outputs the frame bit including at least m-bit information among the frame bits fb25 to fb48 in the second multi-frame to the subscriber line 2. _Two Frame bit f corresponding to _c2 As the line connection unit 21 _Two Is output to the frame bit generating means 28.
[0072]
Similarly, frame bits including at least m-bit information in the third to ninth multiframes are assigned to each subscriber line 2. _Three ~ 2 ₉ Frame bits f corresponding to _c3 ~ F _c9 Each line connection unit 21 _Three ~ 21 ₉ To the frame bit generating means 28.
[0073]
The frame bit generation unit 44 receives the frame bit f from the frame bit distribution unit 43. _c1 Receiving, subscriber line 2 ₁ Frame bits f including multi-frame synchronization patterns F1 to F6, CMB check bits e1 to e6, and m-bit information M1 to M12 for outputting to _d1 Is generated and output to the subscriber line interface 22 at a rate of 8 kbps bit by bit in the order shown in FIG. Here, the frame bit generation unit 44 determines that the frame bit f _c1 The data of M1 among the m-bit information in it is returned to “0” and output.
[0074]
The subscriber line interface 22 adds the frame bits f to the data multiplexed by the third multiplexing means 42. _d1 To make one frame, subscriber line 2 ₁ Output to
[0075]
Similarly, each line connection unit 21 _Two ~ 21 ₉ The frame bit generation means 28 of the frame bit f _c2 ~ F _c9 Each subscriber line 2 _Two ~ 2 ₉ Frame bits f including multi-frame synchronization patterns F1 to F6, CMB check bits e1 to e6, and m-bit information M1 to M12 for outputting to _d2 ~ F _d9 Are generated and output to the subscriber line interface 25 at the rate of 8 kbps one bit at a time in the order shown in FIG.
[0076]
Therefore, each subscriber line 2 ₁ ~ 2 ₉ Is 1.544 Mbps (= 64 k × 24 + 8 k), which matches the data rate of the subscriber line.
[0077]
Since the data rate on the ISDN primary group speed side is slightly faster than the data rate on the leased line side, when data is transmitted from the ISDN primary group speed side to the leased line side, the number of idle flags Fi decreases, and conversely. In addition, when data is transmitted from the leased line to the ISDN primary group speed side, the number of idle flags Fi increases. As described above, since the difference in transmission speed due to multiplexing is absorbed by removing and inserting the idle flag, multiplexing and demultiplexing of D channel data and frame bits can be performed smoothly.
[0078]
When the frame bits of 9 subscriber lines are transmitted using 9 multiframes over the [23 + D] subscriber line as in this embodiment, the m-bit information of each subscriber line is delayed by 9 multiframes. That is, the waiting time of the exchange and the DSU for the m-bit information is much longer than the delay time, so that there is no problem.
[0079]
In the above description, the line connection device on the exchange side has been described. ₁ '~ 2 ₉ 'And leased line 11 ₁ '~ 11 ₉ 'Is exactly the same except for'.
[0080]
As described above, the line connection device 20 of the embodiment is configured such that each [23B + D] subscriber line of ISDN and [24B] subscriber line form a set of a plurality of subscriber lines, The D channel data of the [23B + D] subscriber line is multiplexed and transmitted to a dedicated line corresponding to the [23B + D] subscriber line, and inserted into a specific time slot of a signal input from the dedicated line side. D channel data and frame bits of each subscriber line are separated from the multiplexed data and transmitted to each subscriber line.
[0081]
As a result, frame bits can be transmitted without sacrificing the B channel of each subscriber line. Using the system shown in FIG. 1, a plurality of ISDN subscriber lines are connected by a dedicated line. In the case of extension, a dedicated line section separation test and an ISDN primary rate line section separation test can be performed in the same manner as a normal subscriber line when a failure occurs. Further, line error monitoring can be performed not only in the dedicated line section but also in the ISDN primary rate line section.
[0082]
In the present invention, the information transfer amount of the D channel is reduced by one bit from the original information transfer amount by the frame bit. However, as described above, the information transfer amount of the D channel of the ISDN is small, and at the data rate of 64 kbs, There is always enough margin, and there is no problem even at 56 kbps.
[0083]
When multiplexing frame bits on the D channel and outputting the multiplexed bits to a dedicated line as in the present invention, the CRC calculation result is used as a frame synchronization pull-in condition at point T of a DSU (not shown) for a high-speed digital line. If the CRC calculation result is not used as the frame pull-in condition, there is a possibility that false pull-in may occur, and the ITU-T I.1431 (JT-G704) It is not obligated to use the CRC operation result for establishing frame synchronization.
[0084]
However, this erroneous synchronization pull-in is performed by inverting the polarity of the frame bit from the subscriber line in one line connection device, multiplexing it on the D channel, outputting it to the dedicated line, and receiving the signal, and receiving the signal on the other line connection device side. This does not occur if the polarity of the frame bit is returned to the original and output to the subscriber line.
[0085]
Therefore, regardless of whether the CRC operation result is used as the frame synchronization pull-in condition at the T point of the DSU for the high-speed digital line, the line connection device is configured to invert the frame bits as described above. By doing so, it is possible to prevent erroneous synchronization pull-in of the frame from occurring.
[0086]
Further, in the above-described embodiment, a connection is made between a so-called [1 + 8] subscriber line and a dedicated line, which is a set of one [23 + D] subscriber line and eight [24B] subscriber lines. However, this is not a limitation of the present invention, and the number of subscriber lines of [24B] is arbitrary within the range permitted by the service of ISDN, such as [1 + 1], [1 + 2], [1 + 4], etc. The same can be applied to the case.
[0087]
In the above-described embodiment, the frame bits of the nine subscriber lines are transmitted during the nine multiframes. It is also possible to transmit nine subscriber line frame bits in the number of frames.
[0088]
That is, of the m-bit information, only 6 bits are actually used at the maximum, and only 54 (= 9 × 6) bits are required to transmit the m-bit information of nine subscriber lines.
[0089]
If one bit per multiframe is used to detect the leading multiframe, 11 bits can be used for transmitting m-bit information. It is possible to transmit m-bit information of the actual subscriber line.
[0090]
To realize this, the line connection unit 21 ₁ , The subscriber line 2 ₁ ~ 2 ₉ Of the 12-bit m-bit information, including the information actually required to be transmitted, is compressed to 6 bits, and the compressed subscriber line 2 is compressed from the first multi-frame to the fifth multi-frame. ₁ ~ 2 ₉ 6-bit m-bit information may be inserted continuously.
[0091]
In this case, it is necessary to make the processes of the frame bit distribution unit 43 and the frame bit generation units 44 and 28 correspond to the multiplexing process of the frame bit multiplex generation unit 35.
[0092]
Of the m-bit information from the DSU side of the ISDN, the bits actually required to be transmitted are 6 bits of M2, M4 to M7, and M10, whereas the m-bit information of the m-bit information from the ISDN exchange side is The bits that actually need to be transmitted are the four bits M2, M3, M7, and M10. Of these four bits, M2, M7, and M10 are the bits of the m-bit information from the DSU that actually need to be transmitted. It is included, but M3 is not included.
[0093]
For this reason, when connecting between the subscriber line from the ISDN DSU and the dedicated line, the 12-bit m-bit information is compressed to 6 bits of M2, M4 to M7 and M10 and output to the dedicated line side. When a connection is made between a subscriber line from an ISDN exchange and a dedicated line, 12-bit m-bit information is obtained by adding, for example, M4 and M5 to 4 bits of M2, M3, M7 and M10. Compress to bits and output to dedicated line side.
[0094]
Therefore, the line connection device on the DSU side and the line connection device on the exchange side are not completely the same processing depending on whether or not the M3 bit is processed, but the method of compressing m-bit information into 6 bits as described above. Has the advantage that [1 + 8] subscriber line frame bits can be transmitted with the minimum number of multiframes.
[0095]
Further, by compressing the 12-bit m-bit information into 7 bits of M2, M3 to M7, and M10, the m-bit information from the ISDN DSU and the m-bit information from the ISDN exchange can be reduced. Can be handled by the same processing, and the line connection devices on the DSU side and the exchange side can be made completely the same.
[0096]
In this case, 63 (= 9 × 7) bits are required to transmit the m-bit information of 9 subscriber lines by compressing them into 7 bits, and one detection bit is used per multiframe. In this case, since 11 bits can be used for transmission of m-bit information per multiframe, m-bit information of 9 subscriber lines can be transmitted with 6 multiframes.
[0097]
【The invention's effect】
As described above, the line connection method and the line connection device of the present invention provide a plurality of subscriber lines forming one set of ISDN [23B + D] subscriber line and [24B] subscriber line. Are multiplexed with the D channel data of the [23B + D] subscriber line and transmitted to a dedicated line corresponding to the [23B + D] subscriber line, and a signal input from the dedicated line side is specified. D channel data and frame bits of each subscriber line are separated from the multiplexed data inserted in the time slot and transmitted to each subscriber line.
[0098]
As a result, frame bits can be transmitted without sacrificing the information channel of each subscriber line, and even when a plurality of ISDN subscriber lines are extended by a dedicated line, the dedicated line section can be used in the event of a failure. Isolation and an ISDN primary rate line section isolation test can be performed in the same manner as a normal subscriber line.
[0099]
Further, line error monitoring can be performed not only in the dedicated line section but also in the ISDN line section.
[Brief description of the drawings]
FIG. 1 is an overall view of a system in which a subscriber line is extended using a line connection device of the present invention.
FIG. 2 is a block diagram showing the overall configuration of an embodiment of the present invention.
FIG. 3 is a block diagram showing a configuration of a main part of the embodiment.
FIG. 4 is a diagram for explaining ISDN frame bits;
FIG. 5 is a data diagram for explaining the operation of the embodiment;
FIG. 6 is a data diagram for explaining the operation of the embodiment;
FIG. 7 is a data diagram for explaining the operation of the embodiment;
FIG. 8 is a data diagram for explaining the operation of the embodiment;
FIG. 9 is a data diagram for explaining the operation of the embodiment;
FIG. 10 is a data diagram for explaining the operation of the embodiment;
FIG. 11 is a data diagram for explaining the operation of the embodiment;
FIG. 12 is a data diagram for explaining the operation of the embodiment;
FIG. 13 is a data diagram for explaining the operation of the embodiment;
FIG. 14 is a diagram for explaining an operation of a main part of the embodiment.
FIG. 15 is a diagram showing a frame on the subscriber line side and a frame on the dedicated line side;
[Explanation of symbols]
1 exchange
2 ₁ ~ 2 ₉ , 2 ₁ '~ 2 ₉ ′ Subscriber line
3 ₁ ~ 3 ₉ DSU
4 PBX
11 ₁ ~ 11 ₉ , 11 ₁ '~ 11 ₉ ′ Dedicated line
20 Line connection equipment
21 ₁ ~ 21 ₉ Line connection
22, 25 subscriber line interface
23, 26 Dedicated line interface
27 frame bit buffer
28 Frame bit generation means
30 Multiplex separation processing unit
31 first data writing means
32 1st buffer
33. First data reading means
34 frame bit buffer
35 Frame bit multiplex generation means
36 First multiplexing means
37 Second multiplexing means
38 Separation means
39 Second data writing means
40 Second buffer
41 Second data reading means
42 Third multiplexing means
43 Frame bit distribution means
44 Frame bit generation means

Claims (4)

A plurality of ISDN subscriber lines (23B + D) (2 ₁ ) and [24B] subscriber lines (2 ₂ to 2 ₉ ), and a plurality of subscriber lines and the number of the subscriber lines in line connection method for connecting respectively between the plurality of high-speed digital leased line corresponding (11 ₁ to 11 _9),
Extracting D-channel data at a predetermined rate included in the signal input from the [23B + D] subscriber line and frame bits included in the signal input from each of the subscriber lines;
Storing the extracted D-channel data;
The stored D-channel data is read out at a rate of 7/8 of the predetermined rate, and multiplexed so as to include at least m-bit information of each subscriber line based on the extracted frame bits of each subscriber line. Generating multiplexed frame bits at a rate of 1/8 of said predetermined rate;
Multiplexing the read D channel data and the generated multiplexed frame bits;
Inserting the multiplexed multiplexed data of the predetermined rate into a specific time slot of a high-speed digital leased line corresponding to the [23B + D] subscriber line;
Extracting multiplexed data inserted at the predetermined rate into the specific time slot of a signal input from the high-speed digital dedicated line corresponding to the [23B + D] subscriber line;
Separating the extracted multiplexed data into 7-bit D-channel data and 1-bit frame bits;
Storing the separated D-channel data;
Distributing the separated frame bits for each of the subscriber lines;
Reading the accumulated D-channel data at the predetermined speed;
Generating frame bits to be output to each of the subscriber lines from the allocated frame bits at a rate of 1/8 of the predetermined rate;
Outputting the D channel data read at the predetermined speed to the [23B + D] subscriber line, and outputting the frame bits generated at a speed 1/8 of the predetermined speed to each subscriber line; A line connection method comprising: A plurality of ISDN subscriber lines (23B + D) (2 ₁ ) and [24B] subscriber lines (2 ₂ to 2 ₉ ), and a plurality of subscriber lines and the number of the subscriber lines A line connecting device for connecting between a plurality of high-speed digital dedicated lines (11 _{1 to} 11 ₉ ) corresponding to
D channel data extracting means (22) for receiving a signal input from the [23B + D] subscriber line and extracting D channel data at a predetermined speed from the signal;
A plurality of frame bit extracting means (22, 25) for respectively receiving signals input from the respective subscriber lines and extracting frame bits from the signals;
A first buffer (32);
First data writing means (31) for storing the D channel data extracted by the D channel data extraction means in the first buffer;
First data reading means (33) for reading the D-channel data stored in the first buffer at a rate of 7/8 of the predetermined rate;
Based on the frame bits of each subscriber line extracted by the plurality of frame bit extracting means, multiplexed frame bits multiplexed so as to include at least m-bit information of each subscriber line are set to 1 at the predetermined rate. Frame bit multiplex generation means (35) for generating at a rate of / 8;
Multiplexing means (36) for multiplexing the data output from the first data reading means and the multiplexed frame bits generated by the frame bit multiplexing generation means into the data of the predetermined speed;
The multiplexed data multiplexed by the multiplexing means is inserted into a specific time slot of a high-speed digital leased line corresponding to the [23B + D] subscriber line, and is transmitted to the high-speed digital leased line. Means (23);
Multiplexed data extracting means for receiving a signal from a high-speed digital dedicated line corresponding to the [23B + D] subscriber line and extracting multiplexed data inserted into the specific time slot at the predetermined speed from the signal. 23)
Separating means (38) for separating the multiplexed data extracted by the multiplexed data extracting means into 7-bit D-channel data and 1-bit frame bits;
A second buffer (40);
Second data writing means (39) for accumulating D-channel data at a speed of 7/8 of the predetermined speed separated by the separation means in the second buffer;
Second data reading means (41) for reading the D channel data stored in the second buffer at the predetermined speed;
D channel data transmitting means (22) for transmitting the D channel data output from the second data reading means to the [23B + D] subscriber line;
Frame bit distribution means (43) for distributing the frame bits separated by the separation means for each of the subscriber lines;
A plurality of frame bit generating means (28) for respectively receiving the frame bits allocated by the frame bit allocation means and generating frame bits to be output to each of the subscriber lines at a rate of 1/8 of the predetermined rate; , 44),
A line connection device comprising: a plurality of frame bit transmitting means (22, 25) for transmitting frame bits respectively generated by the plurality of frame bit generating means to each of the subscriber lines. The first data writing unit is configured to remove an idle flag from the D-channel data extracted by the D-channel data extraction unit and write the data into the first buffer,
The first data reading means is configured to output an idle flag instead of the data when there is no data to be read in the first buffer,
The second data writing unit is configured to remove an idle flag from the D channel data separated by the separation unit and write the data to the second buffer,
3. The line connection device according to claim 2, wherein said second reading means is configured to output an idle flag instead of said data when there is no data to be read in said second buffer. The frame bit multiplex generation means,
3. The line connection device according to claim 2, wherein m-bit information of each of said subscriber lines is compressed and multiplexed by removing unused bits.

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