JPS63185134A - Method and apparatus for time division multiplex transmission - Google Patents

Abstract

PURPOSE:To effectively utilize a transmission line by giving priority to a channel having a significant signal among plural input channels and sending a signal with time division multiplexing. CONSTITUTION:A voice signal, a data signal or a picture signal does not always exist in a normal telephone line, data line or picture line, but it is statistically known that the voice signal in, e.g., the voice line contains only nearly 40% of the total time actually, and the time of the significant information sent through the data line or picture line actually is several tens of percentage of the total time. Then various channels with different bit rate are accommodated altogether, channels having a significant signals in plural input channels are given priority and sent with time division multiplexing. Thus, the channels are grouped at each bit rate and are multiplexed in the transmission line frame and the time slots in the frame among the groups are given or take to each other. Thus, the transmission line time slots are efficiently utilized in the entire group to improve the transmission efficiency.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention provides time division multiplexing that collectively accommodates multiple channels with different bit rates and multiplexes them efficiently and flexibly using high-speed digital dedicated lines, etc. The present invention relates to a method and apparatus thereof.

(Prior Art) Conventionally, when a plurality of channels are time-division multiplexed and transmitted, the bit rate of each channel is almost always the same. For example, a P that multiplexes 24 channels of audio lines using a 1°544 Mbps digital line.
In the CM24 line transmission device, all channel bit rates are 64 kbps. Furthermore, even when multiplexing channels with different bit rates, each channel is often multiplexed in a fixed or semi-fixed manner, and if the number of input channels or bit rate changes, etc. It was necessary to temporarily stop system operation and make changes to the system.

(Problem to be solved by the invention) However, in recent years, due to the development of audio encoding technology and the accompanying diversification of services, different bit rates have come to be used for each channel depending on the service and transmission quality. As a result, there is a need for multiplexing equipment that can flexibly respond to changes in the set rate, input channel configuration, and even traffic fluctuations without causing momentary communication interruptions. Conventional techniques cannot meet such demands.

SUMMARY OF THE INVENTION In view of the drawbacks of the prior art, an object of the present invention is to efficiently multiplex a plurality of input channels with different bit rates, and to change bit rates and input channel configurations.
Another object of the present invention is to provide a highly efficient and flexible time division multiplexing method and apparatus that can flexibly respond to traffic fluctuations.

(Means for Solving the Problems) According to the present invention, in a time division multiplex transmission method for time division multiplexing and transmitting a plurality of input channels having different cut rates, the presence of a significant signal among the input channels input channel (active channel))
Input channels with the same bit rate are grouped and multiplexed within a transmission path frame, giving priority to input channels (inactive channels), and when a new active channel occurs among unmultiplexed inactive channels, the new active channel is At least one of the input channels of other bit rates that are multiplexed in a group in which input channels with the same bit rate as the active channel are multiplexed, or immediately before or after the group, according to a predetermined priority order. Select an inactive channel of the channels and multiplex the new active channel in place of the inactive channel, and if the new active channel does not occur, predetermined numbers at the beginning and end of each group in the frame. Move the inactive channels within the group in order to arrange the inactive channels, and if it is not necessary to move such inactive channels, calculate the ratio of the number of inactive channels to the number of active channels for each group □ The ratio multiplexing an unmultiplexed inactive channel of an adjacent group with a low ratio in place of the already multiplexed inactive channel at the beginning or end of the floop with a high ratio so that the difference between groups falls within a predetermined tolerance range; In this way, a time division multiplex transmission method is obtained which is characterized by transmitting multiplexed input channels and multiplexing information indicating change or movement of the multiplexed input channels.

Further, according to the present invention, there is provided a first multiplexing circuit that multiplexes a plurality of input channels, and a channel state memory that stores a channel state signal indicating the presence or absence of a significant signal in the plurality of input channels and its rate. , an assignment information memory that stores channel assignment information indicating which channel is multiplexed on a transmission path among the plurality of input channels; A channel memory circuit that writes or reads information in accordance with the output of the information memory, and the allocation information memory and the channel state memory that determine whether or not a significant signal exists (active/inactive) in the multiplexed and non-multiplexed input channels. and an inactive channel in which no significant signal exists among the channels grouped by bit rate in the transmission frame is predetermined from the allocation information outputted from the allocation information memory. a group condition determination circuit that determines whether the number of active channels is multiplexed at the beginning and end of the group, and a bit that determines the ratio of the number of active channels to the number of inactive channels in the transmission path frame based on the allocation information. the allocation of multiplexing information for updating and moving multiple electrical channels within the transmission path frame based on each output of the balance circuit obtained for each rate, the channel detection circuit, the group condition determination circuit, and the balance circuit; A time division multiplex transmitter is obtained, comprising a time slot allocation circuit that outputs to an information memory, and a second multiplex circuit that multiplexes the output of the first multiplex circuit and the multiplexed information. It will be done.

(Function) Voice signals, data signals, and image signals are not always present in normal telephone lines, data lines, and image lines; for example, in voice lines, voice signals are actually present only about 40% of the time. It is statistically known that significant information is actually sent only a few tenths of the time on data lines and image lines. Focusing on this point, transmission paths can be effectively utilized by giving priority to channels in which significant signals exist among a plurality of input channels, time-division multiplexing, and transmitting the signals. For example, if this principle is applied to a transmission path that conventionally multiplexed 48 audio channels, it is possible to transmit about 100 audio channels using the same transmission path. The present invention uses the above-mentioned principle by accommodating various channels with different bit rates all at once.The channels are grouped by bit rate and multiplexed within a transmission line frame, and the time within the frame is changed between each group. By exchanging slots with each other, the entire group can efficiently utilize transmission path time slots to improve transmission efficiency. When a time slot in a transmission path frame is fixedly assigned for each bit rate and only those time slots are used to preferentially multiplex channels where significant signals exist (active channels), the number of active channels increases. When there is a shortage of time slots, the time slot cannot be used even if there is an unused time slot for another bit rate.In contrast, in the present invention, transmission is performed for each bit rate. To group channels and make it possible to vary the number of time slots assigned to each group depending on traffic. Specifically, inactive channels sufficient to accommodate at least one channel of the adjacent group are arranged at the boundary of each group,
If there is a shortage of time slots in an adjacent group, time slots for this inactive channel are immediately supplied to the adjacent group, so that each group can mutually compensate for the lack of time slots, and the entire input channel is This makes it possible to use the transmission path effectively. Furthermore, by adjusting the number of inactive channels in each group so that the difference between groups in the ratio of the number of inactive channels to the number of active channels in each group becomes small, the number of active channels, that is, the active channel area is secured. As a result, time slot allocation that can flexibly respond to traffic fluctuations in each group is realized, and time slot allocation can be performed equally for each group.

(Embodiment) FIG. 1 is a block diagram showing one embodiment of the present invention. N-channel input signals from CHI to CHN indicated by the reference numeral 100 are sent to a first multiplexing circuit (MUXI) 11.
0 and is time-division multiplexed, then input to the memory circuit 120 via the signal line 111. Memory circuit 12
0 writes only the signal of the channel to which the transmission line time slot is assigned among the input channels in accordance with the control signal input from the time slot (TS) management circuit 140 via the signal line 141, and stores this as the signal. read out via line 121 to second multiplexing circuit (MUX2) 130
Output to. Channel information indicating the bit rate of each input channel and the presence or absence of a significant signal is input to the TS management circuit 140 via a signal line 150, and based on this channel information, time slots in a transmission path frame are assigned to a time slot in which a significant signal exists. Assign priority to channels. This time slot allocation procedure will be described in detail later using FIG. 2. The TS management circuit 140 outputs multiplexing information for notifying the receiving side of changes in the multiplexing channel, etc. via the signal line 142, and the second multiplexing circuit (MUX2) 130
The signal is multiplexed with the multiplexed channel signal input via the signal line 121 and output via the signal line 131.

Also, from the TS management circuit 140 via the signal line 143,
A signal indicating whether a transmission path time slot is assigned to an input channel is output to each channel. By receiving this allocation information, each channel unit or module knows whether or not its own channel is multiplexed. If it is not multiplexed, for example, it temporarily stores the transmitted data in a buffer and allocates a time slot. The quality of encoding during re-multiplexing can be improved by waiting for the audio encoder and stopping the operation of the audio encoder in synchronization with the decoder to maintain the same internal state of the encoder on the transmitting side and the decoder on the receiving side. Perform controls such as preventing deterioration.

FIG. 2 shows a specific embodiment of the TS management circuit 140 in FIG. The channel information input via the signal line 150 is stored in the channel state memory 200 and then input to the channel detection circuit 220 in synchronization with the allocation information output from the allocation information memory 210 via the signal line 211. . The channel information indicates the presence or absence of a significant signal in the input channel and the bit rate of the signal, and information from channel 1 to channel N is multiplexed in a time-division manner. On the other hand, in the allocation information, information indicating whether each input channel is currently multiplexed on a transmission path is multiplexed in order of channel number, similar to the channel information. Based on this information, the channel detection circuit 220 detects the operating state of the currently multiplexed channel (active/inactive) and a so-called new active channel in which a significant signal has occurred among the non-multiplexed channels, and determines the channel number. , bit rate, etc. are output to the TS allocation circuit 230 . The group condition determination circuit 240 examines the time slot usage status in the transmission path frame from the above-mentioned allocation information, and determines that a predetermined number of inactive channels among the input channels grouped by bit rate are at the beginning of each group and It is determined whether the group is placed at the end, and if it is not placed, the group and the position where it should be placed are sent to the TS allocation circuit 23 via the signal line 241.
Inform 0. Also, allocation information is input to the balance circuit 250 via the signal line 211 in the same way as the group condition determination circuit 240, and for each group, the ratio of the number of inactive channels to the number of active channels multiplexed within the group ( AI ratio) is determined, and it is checked whether the difference between groups in this AI ratio is within a predetermined tolerance range. A group with a large AI ratio means that there are many active channels within the group at that time, and fewer inactive channels compared to this, and when a new active channel occurs, the new active channel replaces the inactive channel within the group. It is relatively easy to get into a situation where channels cannot be multiplexed and even inactive channels of adjacent groups have to be used. On the other hand, a group with a low AI ratio has many inactive channels within the group, which means that it has more capacity to accommodate new active channels than a group with a high AI ratio. Therefore, if this AI ratio is approximately balanced among each group, it will be possible for each group to allocate time slots i to the input channels with approximately the same probability, and the difference in services between groups, that is, due to differences in bit rates, will be Inequality can be eliminated. The balance circuit 250 checks the balance of the AI ratio, and when there is an imbalance in the AI ratio, the balance circuit 250 checks the balance of the AI ratio.
Indicates to allocation circuit 230 that balancing is required. On the other hand, the TS allocation circuit 230 knows the multiplexing/non-multiplexing, active/inactive, intra-frame multiplexing order, etc. of each channel based on the status detection result for each input channel output from the channel detection circuit 220, and the group condition determination circuit 240, Based on the output from the balance circuit 250, it is determined whether to allocate a time slot to a new active channel or change the multiplexing order of already multiplexed channels. This result is signal line 23
1 to the allocation information memory 210, the memory contents of the allocation information memory 210 are updated, and the signal line 142 is also used to send similar multiplexed information to the receiving side.
The second multiplexing circuit (MUX2) in FIG.
It is also output to 130. The operation of this TS allocation circuit 230 will be further explained in detail using FIGS. 3 and 4.

3 and 4 are a flowchart and a transmission line frame format for explaining the operation of the TS management circuit 230. The contents of each operation step (81 to 510) will be explained according to the flowchart. Various data are read from the outside in Sl. This data indicates the status of each person/channel from the aforementioned channel detection circuit 220 and the multiplexing state of multiplexed channels within the frame output from the group condition determination circuit 240 and balance circuit 250. In B2, it is first checked based on data from the channel detection circuit 220 whether or not there is a time slot allocation request from a new active channel in which a significant signal has occurred among non-multiplexed channels, and if there is a request, the process does not proceed to B3. In this case, the process is moved to B4. At B3, it is checked whether or not there is a time slot that can be allocated in the current transmission path frame to the new active channel for which allocation has been requested. The assignable time slots will be explained using FIG. 4. Figure 4 shows N types of bit rates (Bl, B2...) in one frame of the transmission path.
. . BN) are grouped by bit rate into groups Gl, G2 .・
...This is an example of multiplexing within the GN. Within the first group G1, channels with the lowest bit rate B1 are multiplexed, G2. It is assumed that G3 has two and four times as many pit-rays as B1 (B2, B4) channels multiplexed, respectively, and the channels in Gl have one channel per channel.
If it is transmitted using a time slot (TS), G2. G3 requires 2TS and 4TS per channel. Furthermore, the symbol AI in each group means an active channel and an inactive channel, respectively.

Further, AM in the frame is an assignment message for notifying the receiving side of information such as time slot allocation changes, and f is a bit for frame synchronization. Now, assuming that the bit rate of the channel that requested new time slot allocation at 83 in FIG. This is possible as long as there is at least one channel, and even if there is no channel, if there is an inactive channel that can accommodate one channel of pit tray (pit tray) B2 at the right end of adjacent group G1 or left end of group G3, this is possible. It is possible to allocate time slots using Therefore, there are two I channels at the right end of group G1, or two I channels at the right end of group G1.
Even if there is a channel 1 on the left end of 3, G2
Allocation is possible even if there is no I channel within the channel, and in this case new allocation information is created in B5. However, inactive channels other than those within G2, the right end of Gl, and the left end of G3 are not allocated, so that the groups for each bit rate are not broken. This prevents multiple time slots from being allocated to channels at random, simplifies overall control, and allows the necessary time slots to be secured in succession, reducing the time required for time slot allocation and the time slot allocation. The length of the assignment message for sending information to the receiving side can be shortened. In this way, when there is no I-channel within its own group, that is, when traffic becomes busy, each group uses the I-channel at the end of the adjacent group.
You can expand your group by penetrating channels, so that the boundaries of each group automatically move according to the traffic, and the time slots can be used more effectively as a whole. In order for the boundaries of each group to move smoothly in response to traffic, Gl, G2. As shown in G3, I channels for boundary movement are always placed at both ends of each group so that time slots can be exchanged with adjacent groups immediately. For this purpose, it is determined at 84 in FIG. 3 whether one channel exists at the end of each group at least as many times as the number of time slots for one channel of the adjacent group. If there is a shortage of I channels at the group end in B4, allocation change information is created in B6 to move the required number of I channels within the group to the group end. If there is no new allocation request or insufficient group end conditions, the ratio of the number of active channels to the number of inactive channels (AI
The number of inactive channels is adjusted when there is a large disparity between groups regarding (ratio). For example, if the AI ratio of group G1 is 50% and that of G2 is 30%, the group can be It is possible to bring the AI ratios of G1 and 02 closer together. By performing such I-channel multiplexing when a new connection does not require a time slot change regarding group end conditions, the services described above can be equalized. When the AI ratio is balanced, refresh is performed at B9. This was done when no changes were required to the configuration of the multiplexed channels within the frame.
The multiplexing status within the frame (which channels are multiplexed in which time slots) is sent to the receiving side in order to match the multiplexing status between sending and receiving, and the transmission path bits before that time It is not necessary if no bit error occurs because it plays the role of error correction in the case where an incorrect assignment message (AM) is sent to the receiving side due to an error.85.8 in 810.
Each piece of information generated in 6.88.89 is output as allocation information.

FIG. 5 shows an embodiment of a receiving device corresponding to the time division multiplexing transmitting device of the present invention. A received signal input via a signal line 500 is sent to a first separation circuit (DEMUXI) 51.
0 into an assignment message and a multichannel signal, which are input to memory circuit 520 and TS management circuit 530 via signal lines 511 and 512, respectively. In the memory circuit 520, multi-channel signals that are randomly multiplexed and input with respect to channel numbers are rearranged in order of channel numbers according to the assignment information input from the TS management circuit 530 via the signal line 531, and are then sent via the signal line 521. Output. Second separation circuit 54
0, each channel signal is separated and output to each channel via the signal line group 550. The TS management circuit 530 learns the channel configuration in the multiplexed signal sent from the transmitting side based on the assignment information input via the signal line 512, outputs the assignment information to the aforementioned memory circuit 520, and outputs the assignment information to the signal line 512. Information indicating whether the signals of each channel are currently multiplexed is output via line 532.

Based on this information, each channel unit or module sends a synchronization flag bit to the receiving terminal when it is not multiplexed in the case of a data line, or operates a decoder in the case of an audio line. By stopping the encoder in synchronization with the encoder on the transmitting side, control is performed such that the internal state of transmission and reception remains the same and quality deterioration does not occur during remultiplexing. FIG. 6 is an example of the TS management circuit 530 shown in FIG. AM signal decoding circuit 61
At 0, the assignment message (AM) separated from the received signal is input via the signal line 512, and it is decoded to determine what changes have occurred in the configuration of the channel group that is multiplexed within the transmission line frame. A signal for updating allocation information memory 600 is output via signal line 611. In the allocation information memo+7600, a map indicating which channel is multiplexed into which time slot in the currently transmitted frame is created, and the map indicating which channel is multiplexed into which time slot in the currently transmitted frame is created. A map identical to that on the transmitting side is created by sequentially updating the map, and control signals are outputted to the aforementioned memory circuit 520, each channel unit, etc. via signal lines 531 and 532 based on this map.

Note that each of the embodiments described above may be performed by software control instead of hardware, and in particular, T
The S management circuit may be implemented by a commercially available microprocessor.

(Effects of the Invention) As explained above, according to the present invention, it is possible to efficiently adaptively multiplex channels in which significant signals exist among a plurality of channels with different bit rates, and to make efficient use of transmission lines. It is extremely effective in achieving this goal. It should be noted that although there is no particular limitation on signals sent through multiple channels, it is obvious that the present invention is effective even when a single medium such as voice, data, and images or various types of media are mixed. .

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention. 2 and 3 are block diagrams showing an example of the TS management circuit in FIG. 1 and a flowchart showing its processing contents, FIG. 4 is a diagram showing an example of a transmission line frame format, and FIG. A diagram showing an example of a corresponding receiving device, No. 6
The figure is a block diagram showing an example of the TS management circuit in the fifth figure. In the figure, 100--input channel group, 110--first multiplexing circuit (MUXI), 120--
...Memory circuit, 130...Second multiplexing circuit (MUX2), 140.
...TS management blood line, 200...Channel status memory, 210...Assignment information memory, 220...Channel detection circuit, 230...TS allocation circuit, 240...Group condition determination circuit, 250... - Balance circuit 510...first separation circuit (DEMUXI), 520
...Memory circuit, 530...TS management circuit, 54
0... Second separation circuit, 600... Allocation information memory, 610... AM signal decoding circuit. Figure 1 Figure 3 Figure 4 Figure 5 Figure 6 Showa Year Month Day 08□M$13 41, Display of the incident 1988 Patent Application No. 17601 2, Name of the invention Time division multiplex transmission method and device thereof 3. Relationship with the case of the person making the amendment Applicant 5-33-1 Shiba, Minato-ku, Tokyo (423) NEC Corporation Representative Tadahiro Sekimoto 4, Agent 5, Details of the invention in the specification subject to amendment Explanation column 6, Contents of amendment (1) On page 21, line 7 of the specification, [G1 AI ratio is 50
%, G2 is 30%", the AI ratio of rGl is 3.
0%, G2's AI ratio is 50%.''

Claims (2)

[Claims] (1) In a time division multiplex transmission method in which a plurality of input channels with different bit rates are time division multiplexed and transmitted, an input channel (active channel) in which a significant signal exists among the input channels is selected from an input channel (active channel) that does not have a significant signal.
Input channels with the same bit rate are grouped and multiplexed within a transmission path frame, giving priority to inactive channels), and when a new active channel occurs among unmultiplexed inactive channels, it is combined with the new active channel. At least one input channel of another bit rate that is multiplexed within a group in which input channels of the same bit rate are multiplexed or that is multiplexed immediately before or after the group according to a predetermined priority order.
Select an inactive channel of the channels and multiplex the new active channel in place of the inactive channel, and if the new active channel does not occur, predetermined numbers at the beginning and end of each group in the frame. Inactive channels within a group are moved in order to arrange inactive channels, and if such movement of inactive channels is not necessary, the ratio of the number of inactive channels to the number of active channels is calculated for each group and the ratio is calculated. The non-multiplexed inactive channels of the adjacent group with the low ratio are multiplexed in place of the first or last multiplexed inactive channels of the group with the high ratio so that the difference between the groups falls within a predetermined allowable range. A time division multiplex transmission method characterized by transmitting input channels multiplexed in this manner and multiplexing information indicating changes or movements of the multiplexed input channels. (2) a first multiplexing circuit that multiplexes a plurality of input channels; a channel state memory that stores a channel state signal indicating the presence or absence of a significant signal in the plurality of input channels and its bit rate; and a plurality of the input channels; an allocation information memory for storing channel allocation information indicating which channel is multiplexed on a transmission line among the channels; and a multichannel signal outputted from the first multiplexing circuit as an output of the allocation information memory. Based on the outputs of the allocation information memory and the channel state memory, the channel memory circuit to which data is written or read according to A channel detecting circuit detects a channel, and a predetermined number of inactive channels in which no significant signal exists among channels grouped by bit rate in a transmission frame are determined based on the assignment information output from the assignment information memory. A group condition determination circuit that determines whether multiplexing is performed at the beginning and end of a group, and a balance that determines the ratio of the number of active channels to the number of inactive channels in the transmission path frame for each bit rate based on the allocation information. a time for outputting multiplexing information for updating and moving multiple channels within a transmission path frame to the allocation information memory based on each output of the circuit, the channel detection circuit, the group condition determination circuit, and the balance circuit; A time division multiplex transmission device comprising: a slot allocation circuit; and a second multiplexing circuit that multiplexes the output of the first multiplexing circuit and the multiplexed information.