JP2000196620A - Tdm one link transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable one link relay when TDM(time division multiplex) transmission of a voice compressed signal is relayed an ATM(asynchronous transfer mode). SOLUTION: A time division multiplexer 16 receives a time division multiplex signal 22 from an up line 101, makes it undergo multiple separation and outputs a compressed signal 241 of 8 kbps band and channel numbers CH1 to CH30 to a converting part 33. The converting part 33 converts the signal 241 into a signal 331 to which a dummy bit DB is attached with the channel numbers, transmits it to an ATM exchange 19 in 64 kbps transmission band and also transmits the channel numbers CH1 to CH30 from an indicating part 34. The packet assembling part 40 of the exchange 19 receives a RA signal 331 and the channel numbers through an instructing part 41, eliminates the dummy bit DB to return it to the signal 241, adds the channel numbers to it to insert it to a packet and outputs it to a memory 42. A line controlling part 43 transmits a packet string outputted by the memory 42 in the first-come order to an ATM network 18 of 64 kbps transmission band.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a time division multiplex (TDM) transmission line for transmitting a compressed audio signal and an asynchronous transfer mode (A
TM) This is related to a TDM one-link transmission system for connecting to a network.

[0002]

2. Description of the Related Art Remote private branch exchanges are connected by a TDM transmission line via a time division multiplexer. The time-division multiplexing device converts the digital voice signal from the switch into, for example, its signal band.
The transmission efficiency is increased by compressing 64Kbps to 8Kbps and transmitting it as a compressed audio signal. When an asynchronous transfer mode network is interposed in the transmission section, this transmission band is 8 Kbps at the entrance of the ATM network, that is, at the access system.
The compressed audio signal is expanded to the original transmission bandwidth of 64 Kbps and transferred to the exit of the network, where the transmission bandwidth is again 8 Kbps.
It is compressed to bps and transmitted from the TDM transmission line to the private branch exchange.

[0003]

As will be understood from the above description, the time division multiplexing device compresses the audio signal into a transmission band of 8 Kbps to increase the transmission efficiency. However, in an ATM network, a signal of one call having a transmission bandwidth of 8 Kbps substantially occupies a bandwidth of 64 Kbps in the network.
56Kbps was occupied wastefully and could not be used effectively. In addition, since compression and decompression are repeated in the transmission part of the access system to the ATM network, there is a disadvantage that the voice quality is degraded due to this. That is, digital one-link relay of the compressed signal could not be performed.

[0004] It is an object of the present invention to provide a TDM one-link transmission system which solves such disadvantages of the prior art, does not deteriorate voice quality, and eliminates invalid use in an ATM network.

[0005]

According to the present invention, a time division multiplex (TDM) transmission of a compressed audio signal is performed in an asynchronous transfer mode (AT).
M) The transmission method for relaying over a network is to separate the 64 Kbps audio multiplexed signal from the private branch exchange into audio signals for each channel, compress the audio signal bandwidth, and
A signal compression means for converting a compressed signal of a speed lower than 64 Kbps, a compressed signal is allocated to a time slot of a frame, and a channel number of the compressed signal is inserted into a predetermined time slot to form a time-division multiplexed signal. A time-division multiplexing means for transmitting a multiplexed signal to a transmission line, a demultiplexing means for receiving a low-speed multiplexed signal from the ATM network side, demultiplexing the multiplexed signal and outputting a compressed signal, and a transmission band for the compressed signal.
A first time-division multiplexing device having expansion means for expanding and multiplexing the audio signal to 64 Kbps and transmitting the signal to the private branch exchange.

According to the present invention, there is also provided a demultiplexing means for receiving a low-speed multiplexed signal from the first time-division multiplexing device and demultiplexing the multiplexed signal, and a time slot compressed signal output from the demultiplexing means. And a first conversion means for converting the data into a speed conversion signal by adding a dummy bit to the data and outputting the data in a transmission band of 64 Kbps together with the channel number. The speed conversion signal and its channel number are received from the ATM network, and the dummy bits are removed. Second conversion means for converting the compressed signal and the channel number into a low-speed multiplexed signal and transmitting the signal to the first time-division multiplexing apparatus; A second time division multiplexer may be included.

According to the present invention, further, a packet assembling means for receiving a compressed signal and its channel number from the first converting means of the second time-division multiplexing device and forming a packet including the compressed signal and the ATM network, Line control means for receiving the compressed signal packet from the ATM network, extracting the compressed signal and the channel number from the received packet, adding a dummy bit to this to form an expanded signal, and a transmission bandwidth of 64 Kb along with the channel number.
It may include an ATM switch provided with packet decomposing means for outputting the data in ps and transmitting the data to the first time division multiplexer.

Further, according to the present invention, a transmission system for relaying low-speed time-division multiplexing (TDM) transmission of a compressed voice signal by high-speed TDM transmission relays a low-speed TDM signal to high-speed TDM transmission. A first time-division multiplexing device that separates a TDM signal into a compressed signal, adds predetermined dummy bits to the signal, converts the signal into a high-speed converted signal, and transfers the converted signal. The signal and the channel number in multiplexing are multiplexed with other signals to perform high-speed TDM transmission, and the receiving side converts the converted signal into a compressed signal for each channel number and transfers it to the first time division multiplexer. And a second time-division multiplexing device.

According to the present invention, a voice multiplexed signal having a transmission band of 64 Kbps from a private branch exchange is converted into a multiplexed signal of a compressed signal in a TDM section, non-decompressed relay is instructed by adding a channel number, and transmitted. Dummy bits are added to the network and the data is transferred at a transmission bandwidth of 64 Kbps. The ATM switch removes the dummy bits and transfers the data. As a result, in the conventional technology, the invalid use band (5
The invalid use band of the dummy bit of 6 Kbps can be eliminated in the present invention, the transmission efficiency can be increased even in ATM transmission, and the entire section can be transmitted by one link relay. High speed alternatives to ATM
Also in the case of relaying by TDM, one link relay of a compressed signal can be performed by transferring the converted signal to which the dummy bit is added and the channel number in the high speed section.

[0010]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. Referring first to FIG. 2, this embodiment includes one telephone A among a plurality of telephones accommodated in a private branch exchange (PBX) 10 and a plurality of telephones accommodated in another private branch exchange 11. This is a system for exchanging (switching) a voice signal with one of the telephones B via an asynchronous transfer mode (ATM) network 18. Private branch exchanges 10 and 11 are generally connected to their respective terminals A
Transmission bandwidth of 64Kb for voice signal of 4KH _Z
Convert to ps voice multiplex signal and perform call exchange. When the private branch exchanges 10 and 11 are located at remote locations, that is, in long-distance calls, the private branch exchanges 10 and 11 are each connected to a time division multiplexing device (TDM) in an access part having relatively little traffic.
It is housed in an ATM network 18 via 12 and 13.

The time division multiplexer 12 receives a voice multiplexed signal having a transmission band of 64 Kbps from the private branch exchange 10, converts the voice band into a compressed voice signal compressed to a bandwidth of 8 Kbps, and generates a compressed voice signal for a plurality of calls. Are time-division multiplexed and transmitted to the opposing time-division multiplexing device 16 through the transmission line 14. The time division multiplexing device 16 in the ATM network 18 converts the compressed voice signal into a rate conversion (RA) signal by adding dummy bits, and converts this into a transmission rate of the ATM network 18 while maintaining a timing of 8 Kbps for each call. ATM switch at 64Kbps
(ATM) Connect to 19. The ATM exchange 19 removes the dummy bits from the speed conversion signal, returns it to a compressed voice signal, packetizes it, and transfers it within the network 18 at a transmission speed of 64 Kbps.

In the ATM network 18, the opposite ATM switch 20 decomposes the packet of the compressed voice signal transferred at the transmission rate of 64 Kbps, adds a dummy bit, and returns it to the rate conversion signal. The time division multiplexing device 17 accommodated in the ATM switch 20 removes the dummy bit from the speed conversion signal in response to this, and transmits this through the transmission line 15 while maintaining the timing of the speed of 8 Kbps for each call at a transmission speed of 64 Kb.
The data is transmitted to the opposing time-division multiplexing device 13 with ps. The remote time-division multiplexing device 13 time-division multiplexes the received compressed voice signal into compressed voice signals for a plurality of calls and transmits the signal to the private branch exchange 11. Each compressed audio signal is 8K
It has a bandwidth of bps. The private branch exchange 11 has a bandwidth of 8 Kbps.
And of expanding the compressed audio signal, demodulates the audio frequency signal of the speech signal band 4KH _Z. An audio signal transmitted from the telephone B to the telephone A is transmitted in the same manner.

As described above, in this embodiment, the access system between the time division multiplexing devices 12 to 16 and the time division multiplexing devices 17 to 13 transmits the compressed audio signal having the bandwidth of 8 Kbps. On the other hand, the relay system between the time division multiplexer 16 in the ATM network 18 and the time division multiplexer 17 through the ATM switches 19 and 20 is a digital one having a transmission speed of 8 Kbps through the access system. Link transmission.
The private branch exchanges 10 and 11 and the ATM network 18 also accommodate non-voice terminals other than telephones. Therefore, it goes without saying that the signal transmitted through the ATM network 18 is not only the voice signal.

FIG. 1 is a functional block diagram of an embodiment of an access system portion of the system shown in FIG. In this figure, the time division multiplexer 12 to the time division multiplexer 16 and the ATM switch
Although the system up to 19 is shown, the system from the other ATM switch 20 to the time-division multiplexing device 11 through the time-division multiplexing device 17 is the same as that described above, and the illustration and description are omitted. The time-division multiplexers 12 and 16 facing each other are, in the present embodiment,
Up line 101 and down line 10 of transmission line 14 with a transmission speed of 2 Mbps
2 for transmitting and receiving time division multiplexed signals 22 to and from each other.

As shown in FIG. 3, in this embodiment, one unit of the time division multiplexed signal 22 is from the first frame 1F to the eighth frame.
Consisting of 8 frames up to 8F, one frame includes 32 time slots TS0 to TS31 each having 8 bits. A frame synchronization bit (not shown) is inserted in the time slot TS0, and compressed signals of 30 communication channels CH1 to CH30 are inserted in the time slots TS1 to TS31. In the present embodiment, the 17th time slot TS16 of each frame 1F to 8F in the TTC-2M standard digital interface is used as a transmission mode switching signal frame 23, and the channel number of the time slot TS0 to TS31
CH1 to CH30 are inserted and transmitted. The channel number is
The signal of the channel is a compressed audio signal, and is an identity for indicating one-link relay to be relayed without extending the audio band to 64 Kbps in the relay section.

The time-division multiplexing device 12 has a compression unit 24, which converts an audio multiplex signal having a transmission band of 64 Kbps from the private branch exchange 10 into an 8-bit compressed signal 241 having a band of 8 Kbps and a multiplexing unit (MPX). This is a band compression circuit for outputting to 25. Multiplexer 25
Is the time slot TS1 of the time-division multiplexed signal 22 shown in FIG.
Multiplexing circuit for outputting to the uplink 101 by outputting the corresponding channel number CH1 to CH30 of the time slot to the time slot TS16. The time division multiplexing device 12 also has a demultiplexing unit (DMX) 27, which receives the time division multiplexed signal 22 from the opposing time division multiplexing device 16 via the downlink 102, demultiplexes it, and This is a demultiplexing circuit that outputs an 8-bit compressed signal 271 to the decompression unit 28. The decompression unit 28 outputs a compressed signal 27 including channels CH1 to CH30.
1 is a band extending circuit for extending 1 to an 8-bit 64 Kbps signal and sending it to the private branch exchange 12.

The time division multiplexer 16 and the ATM switch 19 are connected to each other via digital interface units (DIF) 30 and 31, and transmit and receive 8-bit signals in a transmission band of 64 Kbps. In this embodiment, the digital interface units 30 and 31 employ a digital interface according to the TTC-2M standard. The time division multiplexing device 16 has a demultiplexing unit 32, which receives the time division multiplexed signal 22 on the uplink 101, demultiplexes it, and compresses the signal 241 of the channels CH1 to CH30.
Is output to the conversion unit 33 at a transmission band of 8 Kbps. The conversion unit 33 adds a dummy bit DB to the compressed signal 241 and converts it into a speed conversion (RA) signal 331 expanded by eight times, as shown in FIG.
This is a circuit for sending CH30 from the instruction unit 34 to the ATM exchange 19. The dummy bit DB converts the compressed signal 241 into a transmission bandwidth of 64 Kbps.
This is an additional signal to prevent the timing from being changed when the data is transmitted again and restored to the bandwidth of 8 Kbps. The time-division multiplexing device 16 also has another conversion unit 35,
Contrary to 33, the RA signal 331 of FIG. 4 is received from the ATM exchange 19, and the channel number CH
1 to CH30, the dummy bit DB of the RA signal 331 is removed, and the RA signal 331 is restored to a compressed signal 241 having a bandwidth of 8 Kbps.
This is a circuit for outputting to the down line 102 from 36.

The ATM switch 19 has a packet assembling unit 40,
This is because the RA signal 331 is received from the time division multiplexer 16 and the channel numbers CH1 to CH30 are received via the instruction unit 41,
Remove dummy bit DB from RA signal 331 and compress signal 241
This is a packet assembling circuit that adds a channel number, assembles the packet into a packet of a predetermined length, and outputs the packet to the memory 42. The memory 42 is a storage circuit for temporarily storing packets on a first-in first-out basis.

The ATM switch 19 also has a line control unit 43. The line control unit 43 sends out the packets output from the memory 42 in the order of arrival of the packet queue to the ATM network 18 having a transmission band of 64 Kbps. This is a circuit that receives a packet from 18 and outputs it to another memory 44. memory
Similarly to the memory 42, a storage circuit 44 temporarily stores packets on a first-in first-out basis. A packet decomposing unit 47 is connected to the output of the memory 44. The packet decomposing unit 47 divides the compressed signal 241 of FIG.
1-Take out CH30, attach dummy bit DB, RA signal 32
This is a packet disassembly circuit that converts the channel numbers to 1 and sends out the channel numbers CH1 to CH30 to the indicator 34 of the time-division multiplexer 16 via the indicator 41.

In the operating state, the time division multiplexer 12 converts the audio multiplex signal having a transmission band of 64 Kbps received from the private branch exchange 10 into an 8-bit compressed signal 241 having a band of 8 Kbps by the compression section 24. The compressed signal 241 is formed into the time division multiplexed signal 22 in FIG. 3 by the multiplexing unit 25, and channel numbers CH1 to CH30 are inserted into the time slot TS16. The compressed signal 241 is
By this insertion, non-decompression relay of the compressed signal is indicated,
The data is transmitted to the up line 101 of the transmission line 14.

The time-division multiplexer 16 receives the time-division multiplexed signal 22 from the uplink 101 in the demultiplexer 32 and outputs the demultiplexed compressed signal 241 and channel numbers CH1 to CH30 to the converter 33 in a bandwidth of 8 Kbps. I do. The conversion unit 33 outputs channel numbers CH1 to
CH30 converts the compressed signal 241 of FIG. 4 into an RA signal 331,
The signal is transmitted to the ATM exchange 19 as an RA signal 331 at a transmission band of 64 Kbps, and the channel numbers CH1 to CH30 are transmitted to the ATM exchange 19 through the instruction unit 34. The packet assembling unit 40 of the ATM switch 19 receives the RA signal 331 from the time division multiplexer 16 and the channel numbers CH1 to CH30 via the instruction unit 41,
The dummy signal DB is removed from the RA signal 331 and the compressed signal 241 is removed.
And adds channel numbers CH1 to CH30, inserts them into the packet, and outputs it to the memory 42. Line controller 43
Is the transmission bandwidth of the packet sequence output by the memory
Transmit to 64Kbps ATM network 18.

In the ATM network 18, the ATM exchange
The ATM switch 20 connected to 19 receives the packet from the ATM switch 19 at its line control unit 43 and stores it in the memory 44. The packet decomposing unit 47 of the ATM switch 20 extracts the compressed signal 241 and its channel numbers CH1 to CH30 from the received packets output from the memory 44 on a first-come-first-served basis, converts them into an RA signal 331 with a dummy bit DB, ~ CH30
Is transmitted to the time-division multiplexing device 17 through the instruction unit 41.
In the time-division multiplexing device 17, the conversion unit 35 is an ATM switch.
The RA signal 331 is received from 20 and the channel numbers CH1 to CH30 are received via the instruction unit 34, the dummy bit DB of the RA signal 331 is removed, and the signal is converted to a compressed signal 241 having a channel corresponding band of 8 Kbps. . Multiplexer 36 of time-division multiplexer 17
Configures the compressed signal 241 into the time-division multiplexed signal 22, inserts the channel numbers CH1 to CH30 into the time slot TS16, and sends it out to the downlink 102 of the transmission path 15.

The time-division multiplexer 13 receives the time-division multiplexed signal 22 from the downlink 102 in the demultiplexer 27, demultiplexes it and outputs it to the decompressor 28 as an 8-bit compressed signal 241. The decompression unit 28 outputs the compressed signals 241 of the channels CH1 to CH30.
Is converted to an 8-bit 64 Kbps signal whose band has been extended and transmitted to the private branch exchange 11.

The present invention provides a time division multiplexing apparatus
The present invention is effectively applied to a connection method with an ATM switch, but is not limited to this. For example, in an application example in which time-division multiplexing devices are mutually connected via a switch having a digital interface of the TTC-2M standard. Is also applied effectively. In this case, furthermore, the above-mentioned transmission mode switching can be dynamically set according to the connection conditions by the connection route identification by the number translation function of the private branch exchange.

FIG. 5 is a diagram showing a relay system of such another embodiment of the present invention, and the same components as those shown in FIG. 1 are denoted by the same reference numerals. In this embodiment, the time-division multiplexing devices 12 and 13 and 16 and 17 transmit the compressed audio signal in the form of the time-division multiplexed signal 22 shown in FIG. In these sections, the time division multiplexed signal 22 is remultiplexed with a time division multiplexed signal 22 from a time division multiplexing device (neither is shown) corresponding to another private branch exchange, and the respective time division multiplexed signals are time multiplexed. The devices 50 and 51 are incorporated into a multiplex transmission line 52 having a transmission band of 64 Kbps. For example, the time-division multiplexing device 16 separates the time-division multiplexed signal 22 and converts it into the compressed signal 241 shown in FIG. 4, converts it into the RA signal 331 to which the dummy bit DB is added, and Transfer to 50. In the time division multiplexer 50, the RA signal 331
And channel numbers CH1 to CH in the multiplexing of RA signal 331.
30 and a similar signal from another time division multiplexer (not shown) are multiplexed and transmitted to the multiplex transmission line 52.

The time-division multiplexing device on the receiving side, 51 in this example
Identifies the RA signal 331 by the channel numbers CH1 to CH30, removes the dummy bit DB from the RA signal 331, and
It is converted to 1 and transferred to the time-division multiplexing device 17. Of course, the transfer of the voice signal from the private branch exchange 11 to the private branch exchange 10 is performed in the same manner. As a result, the transmission bandwidth is 64Kb
Even in the case of ps multiplex transmission, a relay that does not extend a voice signal into a signal having a bandwidth of 64 Kbps, that is, one-link relay can be performed.

In the above-described embodiment, the band of the low-speed compressed signal is 8 Kbps, but the band is higher than this, for example, 16 Kb.
Needless to say, the same can be applied to a compressed signal of ps or 32 Kbps.

[0028]

As described above, according to the present invention, for example, a 64 Kbps audio multiplex signal from a private branch exchange is time-division multiplexed.
In the (TDM) section, the signal is converted into a compressed signal multiplex signal, one-link relay is instructed by adding a channel number, and a converted signal with a dummy bit is sent to the ATM network. For example, 8Kbp
s band, and the receiving side adds the dummy bit again and sends it to the TDM section, so that the conventional compressed signal of 64 Kbps
This eliminates the need for decompression, and allows the conventional unused bandwidth (56 Kbps) of the ATM network to be used elsewhere. Therefore, the efficiency of ATM transmission can be improved, and the efficiency of ATM transmission over the TDM / ATM section can be improved.
Since the link is relayed, the repetition of compression / expansion performed in the prior art is unnecessary in the present invention, and therefore, the quality of voice transmission is improved. In high-speed TDM relay, by transmitting a converted signal and a channel number, one-link relay can be performed in distinction from other signals.

[Brief description of the drawings]

FIG. 1 shows an embodiment of a TDM one-link transmission system according to the present invention.
FIG. 3 is a functional block diagram illustrating a configuration example of TDM / ATM transmission.

FIG. 2 is a transmission system diagram showing a configuration example of an entire relay system including the embodiment shown in FIG. 1;

FIG. 3 is a diagram illustrating a configuration example of a time division multiplexed signal in a TDM section.

FIG. 4 is a diagram illustrating an example of a format of a compressed signal and a speed conversion signal.

FIG. 5 is a diagram illustrating a relay system of TDM / TDM transmission according to another embodiment of the present invention.

[Explanation of symbols]

 10, 11 Private branch exchange 12, 13, 16, 17, 50, 51 Time division multiplexer 18 ATM network 19, 20 ATM exchange

Continued on the front page F-term (reference) 5K028 AA12 KK01 KK03 KK35 MM19 SS05 SS15 TT01 5K030 HB01 HB29 JA01 JA05 KA19 5K051 AA02 AA05 BB01 CC01 DD03 DD05 DD13 HH26 JJ05 JJ09 5K069 AA01

Claims (5)

[Claims] 1. A transmission system in which time-division multiplexing (TDM) transmission of a compressed audio signal is relayed over an asynchronous transfer mode (ATM) network, the method comprises: transmitting a 64 Kbps audio multiplexed signal from a private branch exchange to each channel; A signal compression unit that separates the signal into audio signals, compresses the band of the audio signal, and converts the compressed signal into a compressed signal having a lower speed than the transmission band of 64 Kbps; allocating the compressed signal to a time slot of a frame; A time-division multiplexing means for inserting a number into a predetermined time slot to form a time-division multiplexed signal, transmitting the time-division multiplexed signal to a transmission line, and receiving the low-speed multiplexed signal from the ATM network side, Demultiplexing means for demultiplexing the multiplexed signal and outputting the compressed signal; decompressing the compressed signal into an audio signal having the transmission band of 64 Kbps, multiplexing the signal and transmitting the signal to the private branch exchange. TD, characterized in that it comprises a first time-division multiplexer that includes a stage
M One-link transmission method. 2. The transmission system according to claim 1, wherein the system receives the low-speed multiplexed signal from the first time-division multiplexing device, and demultiplexes the multiplexed signal. First conversion means for adding a dummy bit to the compressed signal of the time slot output by the demultiplexing means to convert the compressed signal into a speed conversion signal, and outputting the converted signal together with the channel number in a transmission band of 64 Kbps; Second conversion means for receiving the speed conversion signal and the channel number thereof, removing the dummy bits and converting the signal into the compression signal for each channel number, and multiplexing the compression signal and the channel number at the low speed. A TDM one-link transmission method, comprising: a second time-division multiplexing device having a time-division multiplexing means for editing a signal and sending the signal to the first time-division multiplexing device. formula. 3. The transmission system according to claim 2, wherein the system receives the compressed signal and its channel number from a first conversion unit of the second time-division multiplexing apparatus, and transmits a packet including the compressed signal and the channel number. Means for assembling packets, sending said packets to said ATM network,
Line control means for receiving the packet of the compressed signal from the network, extracting the compressed signal and the channel number from the received packet, adding the dummy bit to the compressed signal to generate an expanded signal, and outputting the expanded signal together with the channel number in a transmission band of 64 Kbps. And a ATM switch provided with a packet decomposing means for transmitting the packet to the first time division multiplexer.
One link transmission method. 4. The TDM one-link transmission system according to claim 1, wherein the low speed includes any one of 8 Kbps, 16 Kbps and 32 Kbps. 5. A low-speed time division multiplexing (TD) of a compressed audio signal.
M) In a transmission method in which transmission is relayed by high-speed TDM transmission, the method separates the TDM signal into a compressed signal when relaying the low-speed TDM signal to the high-speed TDM transmission. A first time-division multiplexing device for adding a predetermined dummy bit to convert the signal into the high-speed conversion signal and transferring the converted signal; receiving the conversion signal; Multiplex the high speed
A second time-division multiplexing device that performs TDM transmission and converts the converted signal into the compressed signal for each channel number on the receiving side and transfers the signal to the first time-division multiplexing device. TDM one-link transmission method.