JP2545538B2 - Time division multiplexing transmission method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention configures one frame with a predetermined number of time slots and multiframes with a plurality of frames, and outputs from each channel in units of this multiframe. The present invention relates to a time division multiplex transmission method for multiplexing and transmitting digital signals.

[Conventional technology]

The transmission method of time division multiplexed signals using high speed digital lines provided by NTT (Nippon Telegraph and Telephone Corporation) etc. is generally standardized in CCITT.

This standardized transmission method will be described with reference to FIGS. 4 to 6.

FIG. 4 is a configuration diagram of a transmission line showing a configuration of a transmission line until a signal output from a data terminal in a home is time-division multiplexed into a primary-group multiplexed signal. In the figure, 1 is a data terminal. (Hereinafter referred to as DTE), 2 is an in-home line terminating device (hereinafter referred to as DSU) in the home, 3 is a 0th-order group multiplexer (hereinafter referred to as D0MUX), 4 is a concentrating multiplexer within the concentrator (hereinafter referred to as LC), 5 Is a primary group multiplex conversion device (hereinafter 01MUX).

 Next, the operation will be described.

As shown in FIG. 5, for example, the transmission rate from DTE1 to 1200 b / s
When the original data signal of is output, this original data signal is
Sampling is performed at a speed of 9.6 kb / s in U2, and the binary digital signal obtained by sampling is divided into 6 bits, and the 6 bits are status bits (S-bit) indicating communication and non-communication states. And a frame bit (referred to as F bit) for identifying the S bit and the information bit are added before and after the transmission rate of 9.6 kb / s × 8/6 = 12.8
It is sent to D0MUX3 via the subscriber line S1 at a transmission rate of kb / s.

The 8 bits of (6 + 2) are usually called 1 envelope as shown in FIG. 6, and the bearer frame is constructed by this 1 envelope, and the transmission speed in the state where the envelope is assembled (here, it is 12.8 kb / s). Is called bearer speed.

Such an envelope format signal is converted into a universal signal in the D0MUX3 that has been converted to a transmission speed of 64 kb / s, and the universal signal for each channel is multiplexed to form a 0-order group multiplexed signal with a transmission speed of 64 kb / s. Change to.
When the signal thus multiplexed is transmitted to the 0th-order transmission line, a 20-multiframe pattern conforming to CCITT Recommendation X.50 is inserted in the first bit of each octet. Fifth
The figure shows an example in which universal signals for 5 channels are time-division multiplexed. 0 in LC4 due to D0MUX3
Focus and multiplex the data signals multiplexed into the next group to
Send to MUX5. In this way, the 0th-order group multiplexed signal is time-division-multiplexed again with 01MUX5 together with another 0th-order group multiplexed signal, and is changed into a 1st-order group multiplexed signal having a transmission rate of 1.544 Mb / s.

The first-order group multiplexed signal thus multiplexed is the seventh signal.
It has a frame structure as shown. That is, the 0th-order group multiplexed signal having a transmission rate of 64 kb / s is grouped by 8 bits for 24 channels, and a frame synchronizing pulse called F bit is further added to form a frame of 193 bits in total. This frame synchronization pulse (F bit) is used in a multi-frame consisting of 24 frames. That is, 24 F bits are used to identify a frame and detect an error. In this way, a multiframe is composed of a plurality of frames, and the same pattern is repeated by repeating the usage in units of this multiframe. By using the synchronization bits for multi-frames, it is possible to combine and multiplex a plurality of types of digital signals having different speeds such as low speed rate signals or 0th order group multiplexed signals. By the way, NTT (Nippon Telegraph and Telephone Corporation) is a multi-point branching service that can distribute data from a certain point to multiple points for point-to-point service from a certain point to a multiplex signal and send it. Are offered.

Figure 8 shows the concept of this branching service. When the main station is M1, M2, M3, the frame structure is divided into 3 channels, CH1 is M1M2, CH2 is M1M3, CH3 is M2M3 and each channel. Routes are assigned to each station so that branch services between stations can be received.

For example, when data A is sent to CH1 and data B is sent to CH2 and a frame is sent from the master station M1 to the master stations M2 and M3, the master station M2 receives the data A from CH1 and the master station M3 receives the data B from CH2. receive.

In this case, at the branch point B1, the logical product of the frame sent from the master station M2 and the frame sent from the master station M3 is calculated, and the signal of this logical product is sent to the master station M1.

[Problems to be solved by the invention]

Since the conventional multiplex transmission system is configured as described above, it has the following problems.

That is, since multi-frame information is not attached to each route group in the branch service, communication data from multiple stations in the branch service are different from each other in multi-frame transmission which is highly efficient multiplexing. Since the frame timing is set, normal communication cannot be performed unless multi-frame synchronization is taken for each route group.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain a transmission method capable of performing highly efficient transmission using multiframes in a branch service.

[Means for solving problems]

Therefore, according to the present invention, one frame is composed of a predetermined number of time slots, a multiframe is composed of a plurality of frames, and a digital signal output from each channel is used in units of this multiframe by using a multiframe synchronization bit. In a time division multiplex transmission method in which multiple frames are transmitted, and at a branch point, the logical product of frames from two transmission lines is taken and sent to another transmission line to perform transmission between stations, an arbitrary number of the above frames are transmitted. Each time slot is divided into a plurality of groups, each divided group is assigned for communication between each two stations, and a multi-frame synchronization bit is inserted for each group, and also between other stations other than the own station. For the group used for communication of each other, insert a bit of a value that does not interfere with communication between other stations even if logical product is taken at the branch point. For each received frame, the information transmitted to the local station is extracted from each group based on the multi-frame synchronization bit, and the received multi-frame is synchronized with the received multi-frame. Is characterized by.

[Action]

When sending data to each station, information on each preceding is inserted in each group location allocated for communication between the own station and each other station. At this time, a multi-frame synchronization bit is inserted for each group, and a bit having a value that does not interfere with communication is inserted and sent to a group used for communication between other stations unrelated to the local station. On the other hand, the receiving station obtains multi-frame synchronization of the data transmitted from each station based on the multi-frame synchronization bit inserted for each transmitting station, that is, for each group of the above frames.

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention. In FIG. 1A, a frame is divided into a plurality of groups every arbitrary number of time slots, and each divided group is used for communication between two stations. Control means for assigning and inserting multi-frame synchronization bit for each group, 1B disturbs communication between other stations even if logical product is taken at a branch point to a group used for communication between other stations other than the own station Insertion means for inserting a bit of a value that does not exist, when 1C receives a frame, the information transmitted to the local station based on the multi-frame synchronization bit is taken out from each group, and the received multi-frame of a plurality of frames Synchronizing means for obtaining synchronism, and these three members are provided in each station.

 Next, the operation will be described.

FIG. 2 is a block diagram of a frame used in the present invention, in which low speed rate signals or zero-order group multiplexed signals are time-division multiplexed to form a frame of 193 bits. As shown in FIG. 3, when transmitting / receiving information between the main stations M1, M2, M3, M4, the control means 1A divides the frame into six groups, and the divided groups, groups,
For groups, groups, groups, groups, M1M2 for groups, M1M3 for groups, M1M4 for groups, M2M3 for groups, M2M4 for groups,
The group is assigned to be used for M4M3 mutual communication. Thus, for example, master station M1 is master station M2, master station M
3. When sending the data A, B, C to the master station M4, the control means 1A inserts the data A, B, C into the group, the group, and the multi-frame synchronization bit F into each group. However, the inserting means 1B inserts a value which does not interfere with communication between other stations, for example, a value 1 representing 1 in binary system, into the other groups, and sends it. on the other hand,
When the master station M2 sends data G, O, E to M1, M3, M4, the data G, D, E are inserted in the groups, and the value 1 is inserted in the other groups and sent. .

By doing this, for example, at the branch point B1, data A, data
The logical product of the transmission frame 10 of the main station M1 in which B and data C are inserted and the frame 11 which is the logical product of the frames transmitted from the main stations M3 and M4 in which the data H, I, J and K are inserted The frame 12 that has been taken will be transmitted to the main station M2, but since the value 1 that does not interfere with communication is inserted, the communication is not disturbed even if the logical product is taken, and the main station M2 does not interfere with other stations. The data of the group assigned to the communication of, that is, the data A, J, K from the master stations M1, M3, M4 are correctly received by the master station M2. Further, when receiving the frames divided into each group, the synchronizing means 1C synchronizes the data in each group when the multiframe is constructed based on the multiframe synchronizing bit F added to each group. Is possible. That is, in the past, since a multi-frame synchronization bit was inserted for each frame to obtain multi-frame synchronization, a separate control bit of 2 bits for every 6 bits of information was required. Since the frame is divided and the multi-frame synchronization bit is inserted for each group allocated for communication between each two stations, the multi-frame synchronization bit is originally obtained. In addition to the above function, it also functions as a conventional control bit, and the conventional control bit becomes unnecessary.

〔The invention's effect〕

As described above, according to the present invention, one frame is composed of a predetermined number of time slots, a multi-frame is composed of a plurality of frames, and a multi-frame sync bit is used in units of the multi-frame to output digital data from each channel. In a time division multiplexing transmission method in which signals are multiplexed and transmitted, and at a branch point, the logical product of frames from two transmission lines is taken and sent to another transmission line to perform transmission between stations, Divide into multiple groups for each arbitrary number of time slots, and assign each divided group for communication between each two stations.
Insert a multi-frame sync bit for each group,
In addition, the group used for communication between other stations other than the local station inserts a bit of a value that does not interfere with the communication between other stations even if the logical product is taken at the branch point, and exchanges frames with each other. For this, the information transmitted to the local station based on the multi-frame synchronization bit is extracted from each group, and the multi-frame synchronization composed of multiple received frames is obtained. This has the effect of enabling highly efficient transmission using frames.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram of a frame used in the present invention, FIG. 3 is a block diagram showing a branch service in the present invention, and FIG. 4 is a conventional transmission. FIG. 5 is a block diagram showing the configuration of a channel, FIG. 5 is a diagram showing a signal format in each step of a conventional transmission system, FIG. 6 is a block diagram of a conventional bearer frame, FIG. 7 is a block diagram of a conventional frame, and FIG. FIG. 8 is a block diagram of a conventional branch service. 1A: control means, 1B: insertion means, 1C: synchronization means.

Claims (1)

(57) [Claims] 1. A single frame is composed of a predetermined number of time slots, a multi-frame is composed of a plurality of frames, and a digital signal output from each channel is multiplexed using a multi-frame synchronization bit in units of this multi-frame. In the time-division multiplex transmission method, in which the frames are transmitted after being converted, and the logical product of the frames from the two transmission lines is taken at the branch point and sent to another transmission line, the above-mentioned frames are transmitted in an arbitrary number. Each time slot is divided into a plurality of groups, each divided group is assigned for communication between two stations, and a multi-frame synchronization bit is inserted for each group. For the group used for communication, insert a bit of a value that does not interfere with communication between other stations even if a logical product is taken at the branch point. Information is sent and received from each group based on the above multi-frame synchronization bit for the received frame, and multi-frame synchronization consisting of multiple received frames is obtained. A time division multiplexing transmission method characterized by the above.