JP2002368824A - Packet signal transmission system, packet signal transmission terminal and packet signal receiving terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology that can eliminate interruption of communication due to a packet loss with a simple configuration of FAX communication terminals. SOLUTION: When detecting a FAX signal, the voice/FAX transmission device increases number of planes of jitter absorption buffers, changes a codec and mulltiplexes packets.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a technology for transmitting or receiving a FAX signal using a packet communication network.

[0002]

2. Description of the Related Art With the development of communication technology and the spread of communication equipment in the field of information communication, real-time communication of video, audio, FAX signals, and the like is performed through a packet communication network or the like. As a means for transmitting a FAX signal, (1)
There are a FAX signal relay system and (2) a FAX signal framing system. (1) In the FAX signal relay system, FAX
A / D conversion of the signal coded by the terminal and modulated into an analog FAX signal is performed, and then the FAX decoder converts the signal into a digital FAX signal.
Decodes into X signals, divides them into packets for each fixed data,
Sends a packet to the packet communication network. On the packet receiving side, the digital FAX signal received from the packet communication network is encoded by a FAX encoder, D / A converted and converted to an analog FAX signal, and the analog FAX signal is sent to the FAX terminal.
An AX signal is sent. (2) In the facsimile signal framing method, an analog signal encoded by a facsimile terminal and converted into an analog facsimile signal is A / D-converted, then decoded by a facsimile decoder into a digital facsimile signal, and the decoded facsimile signal is converted into a signal. ITU-T Recommendation T. 3
8, the packet is transmitted to the packet communication network, and the packet receiving side converts the packet received from the packet communication network into the ITU-T Recommendation T.8. 38, the converted FAX signal frame data is encoded by a FAX encoder,
A conversion is performed to convert to an analog fax signal, and the analog fax signal is transmitted to the fax terminal.

FIG. 4 shows a configuration of a FAX signal relay system, and FIG. 5 shows a configuration of a FAX signal framing system. In FIG. 4, reference numeral 400 denotes an analog signal input unit for inputting an analog signal from an analog telephone line, and 401 denotes an A / D for converting the input analog signal into PCM data.
A converter 402 is a facsimile signal detector which determines whether or not the converted PCM data is a facsimile signal, and 403 decodes the PCM data into a digital facsimile signal when the input signal is a facsimile signal. Fax decoder,
404 indicates P when the input signal is audio data.
An audio encoding unit that compresses and encodes CM data, 405 is a packet division unit that packetizes the decoded digital FAX signal or compressed and encoded audio data for each fixed data, and 406 is a packet that converts the packetized signal into packets. A signal transmission unit for transmitting to a communication network; 407, a signal reception unit for receiving a signal from a packet communication network; 408, a packet storage unit for temporarily storing received packets to perform jitter control;
FAX 409 encodes received data into PCM data when the stored packet is a FAX signal.
An encoder 410 is an audio decoding unit for decoding received data into PCM data when the stored packet is audio data, 411 is a D / A conversion unit for converting PCM data to an analog signal, and 412 is an analog signal. An analog signal output unit that outputs an analog signal converted to a telephone line. In the above, the analog signal input to the analog signal input unit 400 is converted into a PCM signal by the A / D conversion unit 401.
It is converted to data, and the fax signal detector 402
The PCM data converted by the conversion unit 401 is analyzed,
Determine whether the input analog signal is a FAX signal,
If it is a fax signal, the fax decoder 403
The M data is decoded into a digital facsimile signal, the digital facsimile signal is divided into packets by the packet division unit 405, and then transmitted from the signal transmission unit 406 to the packet communication network. The packet received by the signal receiving unit 407 is stored in the packet storage unit 408. In the method of transmitting a continuous signal as a packet, the received packet is stored in the packet storage unit 408 in order to prevent the reproduction of the discontinuous analog signal due to the irregular delay caused in the communication network.
When the data in the buffer is a digital facsimile signal, the received digital facsimile signal is
X encoder 409 encodes the data into PCM data at regular time intervals, D / A conversion section 411 converts the PCM data into an analog signal, and analog signal output section 412 converts the PCM data into an analog signal.
The analog fax signal is reproduced to the AX terminal.

In FIG. 5, reference numeral 500 denotes an analog signal input unit for inputting an analog signal from an analog telephone line, 501 denotes an A / D converter for converting the input analog signal into PCM data, and 502 denotes a converted signal. FAX signal detector for determining whether PCM data is a FAX signal, 5
03 is PCM when the input signal is a facsimile signal
A facsimile decoder 504 for decoding data into a digital facsimile signal.
TU-T Recommendation T. T.38, which is converted into data for each signal frame according to T.38. An editing unit 505 is an audio encoding unit that compresses and encodes PCM data when the input signal is audio data. A packet facsimile unit for converting a digital facsimile signal for each signal frame or a compression-encoded voice data for each fixed data into a packet, and a signal for transmitting a packetized signal to a packet communication network; A transmitting unit 508 is a signal receiving unit for receiving a signal from the packet communication network, and 509 is a T.509. 38, a packet storage unit for temporarily storing data for each FAX signal frame converted by the editing unit 504 or audio data compressed and encoded by the audio encoding unit 505;
T.10 generates a digital facsimile signal from accumulated data of each facsimile signal frame. 38 analysis part, 5
Reference numeral 11 denotes a FAX encoder that encodes a digital FAX signal into PCM data. 512 denotes an audio decoding unit that decodes compression-encoded audio data when data received from a packet communication network is audio data. 513 denotes PCM data. And 514 are analog signal output units that output analog signals converted to analog telephone lines. In the above, the analog signal input to the analog signal input unit 500 is converted into PCM data by the A / D conversion unit 501, and the FAX signal detection unit 5
02, it is determined whether or not the analog signal input to the A / D converter 501 is a facsimile signal. If the analog signal is a facsimile signal, the facsimile decoder 503 decodes the PCM data into a digital facsimile signal. 38 Editor 504
ITU-T Recommendation T. The packet is converted into a facsimile signal frame according to 38, is divided into packets by a packet division unit 506, and is transmitted from the signal transmission unit 507 to the packet communication network. The packet received by the signal receiving unit 508 is stored in the packet storage unit 50.
9 is accumulated. The method of transmitting a continuous signal as a packet has an irregular delay in a communication network.
In order to prevent the discontinuous reproduction of analog signals due to the delay, the received digital audio data is stored in the packet storage unit 5.
09; 38 analysis unit 510 according to ITU-T Recommendation T.38. The FAX encoder 511 converts the digital FAX signal into PCM data by the FAX encoder 511, and generates the PCM data by the D / A converter 513. Is converted to an analog signal, and the analog FAX signal is
Play back to X terminal.

[0005]

In the above relay system, it is necessary to perform jitter control in the packet storage unit 408 in order to prevent discontinuous analog signal reproduction due to delay. However, in voice communication, it is necessary to suppress voice delay. Since the highest priority jitter control method is used, if the same packet storage method as used for voice communication is used, the packet is discarded if the packet does not arrive within a certain time due to congestion in the packet communication network. Then, the supplementary packet inserted in place of the discarded packet in 408 is encoded by the FAX encoder. For this reason, accurate analog fax
The signal is not reproduced, the signal is ignored on the FAX terminal side,
Fax communication is interrupted. Also, in the above-mentioned frame method, after all the signals from the FAX have been received, the F
In order to create and transmit transmission data to the opposing FAX signal transmission device in AX signal frame units, a timeout occurs at the FAX terminal waiting for the FAX signal response depending on the communication state of the packet communication network, FAX communication may be disconnected halfway. In addition, since both of the above-mentioned methods have the essential functions of encoding (decoding) and decoding (decoding) the FAX signal, they are easily affected by encoding / decoding. It becomes complicated and cost reduction is difficult. In view of the above prior art, the problem of the present invention is (1) F due to packet loss.
Ability to improve image quality by eliminating disconnection of AX communication,
(2) Encoding the FAX signal in a compressed state
/ Decoding (decoding) can be made unnecessary, and (3) the cost can be reduced with a simple configuration of the device. An object of the present invention is to provide a technique capable of solving the above problems.

[0006]

According to the present invention, there is provided a packet signal transmission system for transmitting and receiving digital packet data including a FAX signal as a voice signal via a packet communication network. Means for encoding a fax signal in an uncompressed state, means for multiplexing digital packet data to be transmitted, means for increasing the number of buffer planes for digital packet data to be received, and decoding of an encoded fax signal. And means for performing the operation. (2) Analog voice /
An analog signal input unit for inputting a facsimile signal, an A / D converter for converting the input analog signal into PCM data, and a facsimile for detecting a facsimile signal from the PCM data
A signal detection unit, a facsimile communication control unit that shifts processing to facsimile signal transmission / reception processing when a facsimile signal is detected, an encoding unit that encodes digital voice data, and a packet assembling unit that assembles a packet from the encoded digital data. , And a transmission unit for transmitting a packet to a packet communication network. (3) As a packet signal receiving terminal, a receiving unit that receives a packet from a packet communication network, a jitter buffer control unit that stores a received packet for a certain period of time, and data that decodes data compressed and encoded from the stored packet. A decoding unit, a facsimile signal detection unit for detecting a facsimile signal from the decoded PCM data,
FAX communication control unit that shifts processing to X signal transmission / reception only processing, and D / A that converts PCM data into analog signals
The configuration includes a conversion unit and an analog signal output unit that outputs an analog voice / fax signal.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration example of a voice / fax transmission apparatus as an embodiment of the present invention, in which an analog fax signal input from a calling fax terminal is transmitted to a called fax terminal via a packet communication network. The configuration in the case of reproduction is shown. In FIG. 1, reference numeral 100 denotes an analog signal input / output unit for inputting / outputting an analog signal from an analog telephone line, and 101 denotes an A / D conversion unit for converting an analog signal input to the analog signal input / output unit 100 into PCM data. , 102 are D / A converters for converting digitally encoded data received from the packet communication network into PCM data.
Reference numeral 103 denotes a FAX signal detection unit that determines whether or not the converted PCM data is a FAX signal. 104 denotes a FAX communication control unit that controls a process dedicated to FAX communication. 105 denotes a PC.
Speech encoding unit for encoding M data, 106 is a packet dividing unit for packetizing the encoded data for each fixed data, 109 is a signal transmitting and receiving unit for transmitting and receiving packetized signals on a packet communication network, 108 is A packet storage unit 107 for temporarily storing packets received from the packet communication network and performing jitter control, and a voice decoding unit 107 for coding the stored packets into PCM data.

Hereinafter, the operation of the embodiment of FIG. 1 will be described.
This will be described with reference to the sequence diagram of FIG. 2 in addition to FIG. In response to a call from the calling FAX terminal 200, the called FAX
A call based on the response from the terminal 203 is established, and a voice codec to be used on the packet communication network between the voice / fax transmitting terminal 201 and the voice / fax receiving terminal 202 is determined. FAX communication is started, and a CNG signal (calling signal) from the calling FAX terminal 200 is received by the analog signal input / output unit 100 in the voice / FAX transmitting terminal 201. The received CNG signal is converted into digital PCM data by the A / D converter 101, encoded by the audio encoder 105 with the audio codec determined at the time of the previous call connection, and transmitted to the packet divider 106.
Is packetized into data at regular intervals. Thereafter, the signal transmission / reception unit 109 transmits the ITU-T recommendation H.264 to the packet communication network. RTP protocol (Real
Time Protocol) (protocol for exchanging audio data). The data transmitted via the packet communication network is received by the signal transmission / reception unit 109 in the voice / fax reception terminal 202, and the received packet is stored in the packet storage unit. The stored packet is decoded into PCM data by the voice decoding unit 107, converted into an analog FAX signal by the D / A conversion unit 102, and transmitted to the called FAX terminal 203. Upon receiving the CNG signal, the FAX terminal 203 transmits a CED signal (response signal) to the voice / FAX receiving terminal 202 as a response. An analog signal input / output unit 100 in a voice / FAX receiving terminal 202 receives a CED signal from a called FAX terminal 203 and an A / D converter 101
The PCM data is converted to M data, and the PCM data is sent to the FAX signal detection unit 103. The FAX signal detection unit 103
The CM data is analyzed, and when it is determined that the signal is a CED signal, a FAX signal detection notification is sent to the FAX communication control unit 104. The FAX communication control unit 104 performs negotiation with the voice / FAX transmission terminal 201 again to switch the voice codec used for communication with the voice / FAX transmission terminal 201, and determines the voice codec to use.
TU-T Recommendation G. 711 system (uncompressed audio encoding / decoding system). Then, the fax communication control unit 1
G.04 performs encoding and decoding on the audio encoding unit 105 and the audio decoding unit 107, respectively, according to the ITU-T Recommendation G.104. 7
Instructs to use the 11 method (uncompressed voice coding / decoding method), and minimizes (complements) packet loss (packet loss) even when a network delay occurs.
Therefore, the packet storage unit 108 is instructed to switch the number of buffer planes to the increased number of buffer planes for FAX communication processing as the packet storage amount. Is switched to a method of multiplexing data of N consecutive packets. In FIG. 2, A and C are the FAX signal detection units 10.
3 is a position where CED detection is performed, and B is a voice encoding unit 105.
, D indicates the case where the first codec negotiation after CED reception is not performed.

Hereinafter, a method of multiplexing the data of N consecutive packets will be described. FIG. 3 is an explanatory diagram of the multiplexing method. In FIG. 3, (a) is a diagram of the entire coded data composed of packet data t ₀ , t ₁ ,... T ₇ , and (b) is each multiplexed packet data for transmission when the packet multiplicity M is 3. (C) shows multiplexed packet 1,
In the case where the loss of No. 2 has occurred, since the information in the lost packet is included in other multiplexed packets, the packet data shows that no packet loss has occurred on the receiving side. And the packet is t
₁ is a diagram of packet data on the receiving side when a loss of ₁ and t ₂ has occurred. In the present invention, the multiplicity of a packet is M
, The packets t ₀ , t ₁ ,..., T _M−1 are sent together as one packet, and the next packet is t ₁ , t ₁ ,.
t ₂ ,..., t _M are sent together as one packet ((b)). In other _{words, t N, t N + 1} , ..., t N + M-1 (N =
0, 1, 2,...) Are collectively transmitted as one packet ((b)). In the method of the present invention, even if (M-1) packet losses occur continuously,
Since the information content of the lost packet is included in the other multiplexed packets, signal loss (interruption) due to the packet loss does not occur on the receiving side ((c)). On the other hand, in the conventional method, each of the packets t ₀ , t ₁ ,... Is transmitted independently, so that when a packet loss occurs,
The packet data on the receiving side is a discontinuous signal in which the data is lost. For example, (d) shows discontinuous packet data on the receiving side when a packet loss has occurred in the packets t ₁ and t ₂ . The packet data transmitted via the packet communication network is received by the signal transmission / reception unit 109 in the voice / fax transmission terminal 201, and the received packet is stored in the packet storage unit. The stored packet is decoded into PCM data by the audio decoding unit 107, and the decoded PCM data is sent to the FAX signal detection unit 103. The FAX signal detection unit 103 analyzes the data and analyzes whether the data is a CED signal. When the detection of the CED signal is confirmed, the same processing as the above-described facsimile processing switching procedure on the voice / fax receiving terminal 202 side is performed, and then the signal converted by the D / A conversion unit 102 is called. Is sent to the side FAX terminal 200. Thereafter, the analog FAX signals transmitted from the calling FAX terminal 200 and the called FAX terminal 203 are transmitted through the analog signal input / output unit 100 and the A / D conversion unit 101 without passing through the FAX signal detection unit 103. In accordance with ITU-T Recommendation G. The data is packetized as 711-encoded data, multiplexed, and transmitted to the voice / fax transmission device on the opposite side.

According to the embodiment of the present invention, voice / FA
When a FAX signal input to an X transmission apparatus is output by a voice / FAX transmission apparatus via a network such as a packet communication network, interruption of FAX communication due to packet loss due to transmission delay of the communication network, etc., is prevented, and an image is omitted. Can be transmitted and received without images. Further, a FAX encoder that encodes a FAX signal in a compressed state and a FAX decoder that decodes the encoded signal, which are conventionally required, can be eliminated. Therefore, the device configuration, particularly the circuit configuration, can be simplified, and the cost can be reduced.

[0011]

According to the present invention, in facsimile communication,
Communication interruption due to packet loss can be prevented, and image quality can be improved. The encoding (encoding) / decoding (decoding) of the compression of the FAX signal can be omitted, and the cost of the circuit and the device can be reduced with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration example of a voice / fax transmission device as an embodiment of the present invention.

FIG. 2 is an explanatory diagram of digital audio data extraction in the apparatus of FIG.

FIG. 3 is an explanatory diagram of a packet multiplexing process.

FIG. 4 is a diagram showing a configuration of a conventional FAX transmission device.

FIG. 5 is a diagram showing a configuration of a conventional FAX transmission device.

[Explanation of symbols]

100: analog signal input / output unit, 101, 401, 5
01 ... A / D converter, 102, 411, 513 ... D / A
Converters, 103, 402, 502... FAX signal detectors, 104... FAX communication controllers, 105, 404,
505: voice coding unit, 106, 405, 506: packet division unit, 107, 410, 512: voice decoding unit, 108, 408, 509: packet storage unit, 1
09: signal transmission / reception unit, 200: calling FAX terminal,
201: voice / fax transmission terminal, 202: voice / fax
Receiving terminal 203: Called FAX terminal 403, 5
03: FAX decoder, 409, 511: FAX encoder.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5C075 AB90 CA90 CD20 CD22 CE07 5K030 GA11 HA08 HB04 HC01 JT05 KA01 KA06 KA13 KA19 LD11 5K101 KK01 LL01 NN01 NN18 SS07

Claims (3)

[Claims] A packet signal transmission system for transmitting and receiving digital packet data including a facsimile signal via a packet communication network, means for encoding a facsimile signal in an uncompressed state, and means for multiplexing digital packet data to be transmitted Means for increasing the number of buffer planes of received digital packet data, and means for decoding an encoded FAX signal, wherein the FAX signal is transmitted and received in an uncompressed state. Packet signal transmission system. 2. An analog signal input section for inputting an analog voice / fax signal, and a PC for inputting the input analog signal.
An A / D conversion unit for converting to M data, a FAX signal detection unit for detecting a FAX signal from the PCM data, a FAX communication control unit for shifting the processing to a dedicated FAX signal transmission / reception process when a FAX signal is detected, 1. A packet signal transmitting terminal comprising: a coding unit that codes a packet; a packet assembling unit that assembles a packet from the coded digital data; and a transmitting unit that transmits the packet to a packet communication network. 3. A receiving unit for receiving a packet from a packet communication network, a jitter buffer control unit for storing the received packet for a certain period of time, and a data decoding unit for decoding data compressed and encoded from the stored packet. A facsimile signal detecting unit for detecting a facsimile signal from the decoded pcm data, a facsimile communication control unit for shifting the processing to a facsimile signal transmission / reception dedicated process upon detection of the facsimile signal, A packet signal receiving terminal comprising: a conversion unit; and an analog signal output unit that outputs an analog voice / fax signal.