JPH05236151A - Method for testing line quality of ISDN terminal device and method for controlling ISDN terminal device - Google Patents

Abstract

(57) [Summary] [Objective] To provide an ISDN terminal device capable of realizing a test call. [Configuration] Information for requesting / releasing / confirming test operations is defined in the “user / user” information element,
The test operation can be realized in the loopback 4 mode. As a result, the line quality can be tested individually from end to end, so the cost for testing can be reduced,
In addition, communication efficiency can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line quality test method for an ISDN terminal device using ISDN as a transmission line, and I
The present invention relates to a control method of an SDN terminal device.

[0002]

2. Description of the Related Art In recent years, ISDN is being developed as a network in each country, and along with it, international ISD
N communication is also being realized. This International I
During SDN communication, the following inconveniences may occur because the quality of the lines established with the partner terminal varies.

For example, when the international ISDNs are connected by a satellite line, the line delay time becomes very large as compared with the case where they are connected by a terrestrial line. For this reason, IS
In the initial setting state of the DN terminal, for example, the value of the communication parameter depending on the communication quality (here, the line delay time) such as the window size, the packet size, and the link timer may be inappropriate. Data transmission with the partner terminal may become impossible.

When data transmission frequently ends in error with a specific terminal, the own terminal connects to the communication path established between the own terminal and the other terminal. Which is the domestic ISDN that is present, the international gateway (international ISDN) on the home side, the international gateway (international ISDN) on the country side of the partner terminal, between the international gateways, and the ISDN of the partner country to which the partner terminal is connected However, the line quality often deteriorates.

[0005] In this case, it is possible to request a network operator, which provides each ISDN for the communication path, to trace and check the line quality. However, such a follow-up investigation may take a very long time, and it is difficult to use it as a material for promptly solving a situation where a specific data transmission ends in error. Also, even if it is found that the line quality in any ISDN is poor,
If there is no other ISDN that can be replaced, there is no choice but to tolerate such poor line quality.

[0006] Therefore, for example, when the satellite path is included in the communication path with the partner terminal, the window size,
It is advisable to set the packet size, link timer, etc. to values corresponding to the delay time. So, for example,
If the ISDN number of the other terminal specified at the time of calling includes a country code, the window size, packet size, link timer, etc. are reset to values for the satellite line.

When data transmission frequently ends in error with a specific terminal, instead of the own terminal and the partner terminal, a measuring device for measuring the line quality is provided in the socket of each basic interface. To measure the line quality directly. Then, the value of the communication parameter such as the window size, the packet size, and the link timer that depends on the line quality may be set to a value according to the measured line quality.

[0008]

However, in such a method, it is necessary to use a measuring device for measuring the line quality, and there is a disadvantage in that the cost for the measurement is high. Further, when the communication parameter value is set to a value corresponding to the delay time in the satellite line, the window size and the packet size also depend on the bit error rate, so those set values are not always the optimum values. There may be the inconvenience.

The present invention has been made in view of the above circumstances, and provides a line quality measuring method of an ISDN terminal device and a control method of an ISDN terminal device capable of measuring the line quality in a communication path established with a partner terminal. It is intended to be provided.

[0010]

According to the present invention, in a line quality test method for an ISDN terminal device using ISDN as a transmission line, the test terminal adds information indicating that a loopback mode test is to be performed to a call setup message. In this state, the terminal under test is called, and the terminal under test adds the information indicating that the loopback mode test is performed to the call setting message received when the incoming call is detected,
Information indicating that the test execution is confirmed is added to the response message during the call setup procedure, and a loopback mode is set in which the received data is returned directly as the transmitted data on the information channel. When information indicating test execution confirmation is added to the message received from the terminal, the predetermined test pattern data is transmitted after the information channel is established, and the terminal under test is transmitted based on the reception result of the test pattern data. The quality of the line set up between and is determined.

An IS using ISDN as a transmission line
In the line quality test method of the DN terminal device, the test terminal calls the terminal under test with the information indicating that the loop back mode test is to be performed added to the call setting message, and the terminal under test detects the incoming call. If the received call setup message has information indicating that a loopback mode test is to be performed, the message that responds during the call setup procedure will also include information that confirms that the test is being performed. A loopback mode is set in which the received data is directly looped back as transmission data on the channel, and the test terminal, when the information indicating the test execution confirmation is added to the message received from the terminal under test, establishes a predetermined channel after the information channel is established. The test pattern data is transmitted, and the test pattern data is received based on the reception result of the test pattern data. With determining the quality of the tensioned line between the terminal, in which to output displays the determination result.

An IS using ISDN as a transmission line
In the line quality test method of the DN terminal device, when the data transmission in the normal mode does not end normally, the transmitting terminal
Recall the terminal under test with the call setup message including information indicating that a loopback mode test is to be performed, and the terminal under test will perform a loopback mode test on the call setup message received when an incoming call is detected. When the information that indicates the test is added, the information that indicates that the test execution is confirmed is added to the message that responds during the call setup procedure, and the received data is looped back directly as the transmitted data on the information channel. When the message received from the terminal under test has information indicating test execution confirmation added, the test terminal sends predetermined test pattern data after the information channel is established, and the test pattern data Based on the reception result, the quality of the line established with the terminal under test is determined and It is obtained by such displays and outputs the determination result.

Information indicating that a loopback mode test to be added to the call setup message is to be performed is as follows:
Any one of a user-user information element, a source sub-address information element, a destination sub-address information element, a lower layer compatibility information element, or a higher layer compatibility information element 1
You should use one.

The test terminal sets and saves various parameter values depending on the communication quality at the time of data transmission when the terminal under test is the destination terminal, based on the line quality judgment result. At the time of data transmission, the values of the above various parameters stored corresponding to the destination terminal at that time are
It may be set at the time of data transmission.

IS using ISDN as a transmission line
In the line quality test method of the DN terminal device, when the normal mode data transmission is not normally completed, the transmitting terminal, in a state where the call is held, adds information indicating that the loopback mode test is to be performed by the transmitting terminal. When an information message is sent to the receiving terminal, and the receiving terminal receives a user information message with information indicating that a loopback mode test is to be performed during data transmission operation, the information indicating that the test execution is confirmed In addition to responding to the sending terminal with a user information message, the loopback mode is set to return the received data directly as sending data on the information channel, and the sending terminal is added with information indicating the test execution confirmation from the receiving terminal. When the user information message is received, the specified test pattern data is sent and Based on the reception results of the test pattern data, it determines the quality of the tensioned line between the reception terminal, in which to output displays the determination result.

An IS using ISDN as a transmission line
In the line quality test method of the DN terminal device, when the normal mode data transmission is not normally completed, the transmitting terminal, in a state where the call is held, adds information indicating that the loopback mode test is to be performed by the transmitting terminal. When an information message is sent to the receiving terminal, and the receiving terminal receives a user information message with information indicating that a loopback mode test is to be performed during data transmission operation, the information indicating that the test execution is confirmed In addition to responding to the sending terminal with a user information message, the loopback mode is set to return the received data directly as sending data on the information channel, and the sending terminal is added with information indicating the test execution confirmation from the receiving terminal. When the user information message is received, the specified test pattern data is sent and Based on the reception result of the test pattern data, the quality of the line established with the receiving terminal is judged, the judgment result is displayed and output, and the information indicating the cancellation of the loopback mode test is added. Sends the user information message to the receiving terminal, and when the receiving terminal receives the user information message with the information indicating the cancellation of the loopback mode test, it indicates that the loopback mode is canceled and the cancellation of the loopback mode is confirmed. The user information message with the information added is responded to the transmitting terminal, and the normal data transmission mode is entered.
When a user information message added with information indicating confirmation of cancellation of the loopback mode is received, transmission data is transmitted in the normal data transmission mode.

The transmitting terminal sets and saves various parameter values depending on the communication quality at the time of data transmission when the receiving terminal is the destination terminal, based on the line quality judgment result, and stores the data. At the time of transmission, it is advisable to set the values of the various parameters stored corresponding to the destination terminal at that time at the time of data transmission.

IS using ISDN as a transmission line
In the control method of the DN terminal device, when the data transmission in the normal mode does not end normally and the reason why it does not end normally is the non-connection of the partner terminal, information indicating the non-connection of the receiving terminal at that time is displayed. While saving
When the information indicating the non-connection of the above-mentioned terminal is stored for the other terminal specified at the time of calling, the selection of the other terminal at that time is judged to be an error operation, and a message to that effect is displayed and the processing ends in error. It is a thing.

[0019]

Therefore, the test for measuring the line quality is
This can be performed by the SDN terminal alone, and the cost required for measuring the line quality can be greatly reduced. Further, if a test for measuring the line quality is performed subsequent to the normal data transmission, the test for measuring the line quality is performed only with a partner terminal that needs the communication, so that the communication cost can be reduced.
Further, since the values of the communication parameters that depend on the line quality are set according to the measured line quality, optimum values are set for these communication parameters and the efficiency of data transmission can be improved.

[0020]

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows a group 4 facsimile apparatus according to an embodiment of the present invention. The group 4 facsimile machine uses ISDN as a transmission path.

In FIG. 1, a control unit 1 mainly performs control processing of each unit of the group 4 facsimile machine, and a system memory 2 executes a control processing program executed by the control unit 1 and a processing program. In addition to storing various kinds of data necessary for the operation, the work area of the control unit 1 is configured, and the parameter memory 3 is for storing various kinds of information unique to the group 4 facsimile machine. ..

The scanner 4 is for reading an original image at a predetermined resolution, the plotter 5 is for recording and outputting an image at a predetermined resolution, and the operation display unit 6 is a facsimile device. For operation,
It consists of various operation keys and various indicators.

The encoding / decoding unit 7 is for encoding and compressing the image signal and for decoding the encoded and compressed image information into the original image signal, and the image processing unit 8 is for the image processing unit 8. The image storage device 9 stores a large amount of image information in a coded and compressed state.

The ISDN interface circuit 10 is for connecting the group 4 facsimile apparatus to the ISDN, and the layer 1 signal control section 11 has a layer 1 signal processing function and a D channel (signal channel) signal. Loopback 4 that has the function of integrating / separating the signals of one B channel (information channel), sets the received data as it is to the transmitted data, and returns the received data.
It is equipped with a mode line test function.

The D channel transmission control section 12 is for executing signal processing on the D channel of ISDN such as call setup / call release procedure processing, and the B channel transmission control section 1
Reference numerals 3 and 14 are for realizing the group 4 facsimile transmission procedure function performed on the B channel.

These control unit 1, system memory 2,
The parameter memory 3, the scanner 4, the plotter 5, the operation display unit 6, the encoding / decoding unit 7, the image processing unit 8, the image storage device 9, the D channel transmission control unit 12, and the B channel transmission control units 13 and 14 are , And is connected to the system bus 15, and data is exchanged between these respective elements mainly via the system bus 15. Further, the exchange of data between the layer 1 signal control unit 11 and the control unit 1 is also carried out via this system BAS15. In addition, data exchange between the layer 1 signal control unit 11 and the D channel transmission control unit 12, and
Layer 1 signal control unit 11 and B channel transmission control unit 13,
The exchange of data with 14 is performed directly.

FIG. 2A shows an example of a call control procedure in the circuit switching mode performed by the terminal device connected to the ISDN with the ISDN.

That is, the calling terminal first sets the circuit switching mode as the transfer mode, and sends a call setting message SETUP with the destination terminal as the destination to the ISDN to request call setting with the called terminal. Sends a call setup message SETUP to the designated destination terminal to make a call. The ISDN also sends a call setting acceptance message CALL_PROC for notifying the call setting status to the calling terminal.

Upon detection of an incoming call, the called terminal sends a calling message ALERT to the ISDN when the called terminal is ready to receive a call, and the ISDN sends a calling message ALERT to the calling terminal to call the called terminal. Notify that it has started.

When the called terminal responds to the incoming call, it sends a response message CONN to the ISDN, and the ISDN sends a response message CONN to the calling terminal to notify that the called terminal has accepted the call.

Also, the ISDN sends a response confirmation message CONN_ACK to the destination terminal to confirm the response of the destination terminal, and at that time, an information channel (B channel) for data transmission between the source terminal and the destination terminal. Is established.

As a result, the data transmission using the information channel is performed between the calling terminal and the called terminal by the transmission control procedure set in the transmission function of each terminal.

When the data transmission is completed, the calling terminal sends a disconnect message DISC to the ISDN to request the release of the information channel, and the ISDN releases the release message R.
EL is sent to the calling terminal to notify the restoration of the information channel. On the other hand, the ISDN sends a disconnection message DI to the destination terminal.
SC is sent to request the release of the information channel, and the destination terminal sends a release message REL to ISDN to notify the restoration of the information channel.

As a result, the calling terminal IS sends the release completion message REL_COMP for notifying the completion of the channel disconnection.
In response to the DN, the information channel between the calling terminal and the ISDN is released. At the same time, the ISDN sends a release completion message REL_COMP to the destination terminal,
The information channel between N and the called terminal is released. As a result, the information channel established between the calling terminal and the called terminal is completely released.

In this way, the information channel is set between the calling terminal and the called terminal, data transmission is performed, and when the data transmission is completed, the information channel is released.

Further, each message for ISDN call setup is, as shown in FIG. 3A, a protocol specification (format, format,
Protocol identifier to identify the sequence, etc.)
Call number to identify which call the message pertains to, message type to identify the content of each message, mandatory information elements that must be added to each message, and each message It consists of additional information elements added as required. Note that 0, 1, or a plurality of essential information elements are set according to the message type, and 0, 1, or a plurality of additional information elements are arranged according to the situation.

The call setup message SETUP is, as shown in FIG. 7B, a "transmission capability" as an essential information element.
And the additional information element is, for example, "calling number",
"Calling subaddress", "Called number", "Called subaddress", "Lower layer compatibility", "Higher layer compatibility",
It also has information elements such as “user / user”.

The user information message USER_INFO used for information transfer between users has a "user-user" information element as an essential information element.
In addition, the response message CONN has a "user-user" information element as an additional information element.

An outline of these information elements will be described.

The "transfer capability" information element is an information transfer indicating whether the content of the information to be transmitted is voice, unrestricted digital information, restricted digital information, 3.1 KHz audio, 7 KHz audio, or video. Capability, transfer mode indicating whether the switching function used is circuit switching or packet switching, information transfer speed indicating information transfer speed, information indicating information transfer mode, and information indicating user information protocol, etc. Consists of.

The "calling number" information element is the ISDN of the calling terminal.
Represents a number, and the "originating subaddress" information element represents the subaddress set in the originating terminal. The "Called Number" information element represents the ISDN number of the called terminal,
The “destination sub-address” information element represents the sub-address set in the destination terminal. Where the subaddress is
Each can define its own format, and can be applied to, for example, display the settings of its own service.

The "Lower layer compatibility" information element is for use in the communication possibility check with the partner terminal,
The basic contents are the same as the “Transmission capability” information element. Furthermore, this "lower layer compatibility" information element contains more detailed content.

The "higher layer compatibility" information element is used for the consistency check with the partner terminal. For example, group 2 / group 3 facsimile, group 4
The terminal function of the facsimile, mixed mode, teletex, videotex, telex, or message handling system is displayed.

The "user-user" information element is intended to be used to convey information between users, the content of this "user-user" information element being transferred transparently without being interpreted by ISDN. It is transmitted to the other user. In this case, the "user-user" information element is used to control the line quality test of the loopback 4, and the test mode designation information and the test / normal switching parameter are set as shown in FIG.

Here, the test mode designation information is for exchanging "request for test mode", "release of test mode", and "confirmation of test mode" between terminals. Any one of the values shown is set. The test / normal switching parameters are
"Test communication", "Switching from test communication to normal communication",
This is for designating "switching from normal communication to test communication" and "test communication" between terminals, and any one of the values representing the parameters is set.

FIG. 5 shows an example of the line quality test transmission performed in this embodiment.

In this line quality test transmission, the test terminal
First, the terminal under test is designated as the destination, the "test mode request" is set in the test mode designation information of the "user / user" information element, and the "test communication" is set in the test / normal switching parameter. Message SET
A UP (test request) is sent to the ISDN to request call setup with the terminal under test, and the ISDN sends a call setup message SETUP (test request) to the designated terminal under test to make a call. The ISDN also sends a call setting acceptance message CALL_PROC for notifying the call setting status to the test terminal.

The terminal under test sends the call setup message SETU.
When P (test request) is received, the layer 1 signal control unit 11
The loopback 4 mode to the "user user"
ISD the response message CONN (test confirmation) in which "test confirmation" is set in the test mode specification information of the information element and "test communication" is set in the test / normal switching parameter
ISDN sends the response message CONN (test confirmation) to the test terminal to notify that the terminal under test has accepted the call.

Further, the ISDN sends a response confirmation message CONN_ACK to the terminal under test to confirm the response of the terminal under test, and at that time, an information channel (for data transmission between the test terminal and the terminal under test) ( B channel) is established.

At this time, as shown in FIG. 6, the terminal under test TEb switches the information channel layer 1 to the loopback 4
The mode is set to the mode, and for the information channel established at that time, the received data is returned as transmission data and transmitted.

Therefore, the transmission data TXa sent from the test terminal TEa is ISD via the network terminating device NTa of the basic interface to which the test terminal TEa is connected.
The data is transferred to N, is sent by ISDN to the network terminating device NTb of the basic interface to which the terminal TEb to be tested is connected, as received data RXa, and is received by the terminal under test NTb via the network terminating device NTb.

At the terminal under test NTb, the received data RXa
Is returned as is as transmission data TXb, this transmission data TXb is transferred to ISDN via network terminating device NTb, is sent as reception data RXb to network terminating device NTa by ISDN, and is tested via network terminating device NTa. It is received by the terminal TEa.

Therefore, the test terminal TEa, as shown in FIG. 7, includes a synchronization signal having a predetermined bit pattern, a header,
Also, the test data including the test pattern is transmitted. Here, as the header, for example, predetermined bit pattern data having strong autocorrelation can be used. As the test pattern, for example, CCITT Recommendation I. The test bit pattern data defined by 430 can be used.

This test data passes through the path as described above and is returned at the terminal under test TEb to return to the test terminal T.
Received at Ea. At this time, the test terminal TEa activates a delay time timer for measuring the delay time TD at the time of transmitting the header of the test data, detects the synchronization with the synchronization signal of the received data, and then detects the header. The delay timer is stopped. Also, when the test pattern is received, the data error is detected.

When the test data transmission is completed in this way, the test terminal (test terminal TEa) sends a disconnection message DISC to the ISDN to request the release of the information channel, and the ISDN sends the release message REL. It is sent to the test terminal to notify the restoration of the information channel. On the other hand, to the terminal under test (terminal TEb under test), ISDN sends a disconnect message DISC to request the release of the information channel, and the terminal under test sends a release message REL to ISDN to notify the restoration of the information channel. To do.

As a result, the test terminal sends the release completion message REL_COMP to notify the completion of channel disconnection.
In response to the SDN, the information channel between the test terminal and the ISDN is released. At the same time, the ISDN sends a release completion message REL_COMP to the terminal under test, and the information channel between the ISDN and the terminal under test is released. As a result, the information channel set up between the test terminal and the terminal under test is completely released.

In this way, the information channel is set between the test terminal and the terminal under test, the test data transmission is performed, and when the data transmission is completed, the information channel is released.

Further, the test terminal TEa forms line quality information as shown in FIG. 8 based on the result of the line quality test transmission at that time and stores it in the parameter memory 3.

This line quality information is an ISD for storing the ISDN number of the other terminal (terminal under test) at that time.
N number information, connection / non-connection flag for storing whether the partner terminal is connected or not connected, transmission delay information for storing transmission delay time, bit error rate for storing bit error rate Information, Layer 3 and Layer 5
Window size information for storing the window size, packet size information for storing the layer 3 packet size, and link timer value information for storing the link timer value.

Here, the value of the above-mentioned delay time timer is set in the transmission delay information. The bit error rate information is set to a value obtained by dividing the number of bit errors when receiving the test pattern data by the number of bits of the test pattern data. The values of the window size information and the packet size information are set to the values of the delay time information and the value of the bit error rate information calculated by applying a well-known arithmetic method. The value of the link timer value information is set to a value calculated by applying a known calculation method to the value of the delay time information.

The connection / non-connection flag is set to a value representing "connection" as an initial value. Then, when a specific situation occurs such that it can be determined that the other terminal is not connected, for example, during data transmission in the normal mode,
Even if the call setup procedure ends normally and an information channel is established with the other terminal, response data cannot be obtained for the command of the information channel layer 2 sent from the own terminal. Only when they occur, set the value indicating "not connected" in the connected / not connected flag.

At the time of calling, the line quality information of the ISDN number of the designated partner terminal is taken out, and the value of the connection / non-connection flag is checked first. When a value indicating "not connected" is set in this connection / disconnection flag, data transmission with the specified partner terminal is not possible, so an error message indicating that is displayed on the operation display unit 6. And ends with an error.

When a value indicating "connected" is set in the connection / non-connection flag, the values of the window size information, packet size information, and link timer value information of the line quality information are used at that time. B channel transmission control units 13 and 14 are set, and a normal call setup procedure is executed to establish an information channel with the partner terminal.

After that, a predetermined group 4 facsimile transmission procedure is executed using the established information channel to transmit the transmission image information to the partner terminal, and when the image information transmission operation is completed, a predetermined call disconnection recovery procedure is executed. After that, the series of image information transmission operations is completed.

As described above, in this embodiment, the optimum value of the communication parameter depending on the line quality is calculated using the result of the line quality test transmission performed with the partner terminal, and the optimum value is used. Since the image information is transmitted, the image information can be transmitted efficiently.

Since the line quality can be tested only by the terminal, the cost required for the line quality test can be greatly reduced.

In the above-described embodiment, the line quality test transmission is performed independently, but the line quality test transmission operation and the data transmission operation can be performed continuously in the same call. An example of the transmission procedure in that case is shown in FIG.

In this transmission procedure, the originating terminal first designates the destination terminal as the destination, and sends the call setup message SETUP (test request) similar to that in the above-mentioned embodiment to the ISDN to establish the call with the destination terminal. The ISDN sends a call setup message SETUP (test request) to the designated destination terminal to make a call. Also, the ISDN sends a call setup acceptance message CALL_P for notifying the call setup status.
The ROC is sent to the calling terminal.

The destination terminal sends a call setup message SETUP.
When the (test request) is received, the layer 1 signal control unit 11 is instructed to perform the loopback 4 mode, the same response message CONN (test confirmation) as in the above-described embodiment is sent to the ISDN, and the ISDN sends the response message CONN (test). Confirmation)
To the calling terminal to notify that the called terminal has accepted the call.

The ISDN also sends a response confirmation message CONN_ACK to the destination terminal to confirm the response of the destination terminal, and at that time, an information channel (B channel) for data transmission between the source terminal and the destination terminal. Is established. And
Using the established information channel, the calling terminal sends and receives the test data and performs the same line quality test operation as in the above-described embodiment.

When the test operation is completed, the calling terminal sets "test mode release" in the test mode specification information of the "user / user" information element and sets "test communication to normal communication" in the test / normal switching parameter. The user information message USER_INFO (test cancellation) with "switch" set is sent, and the ISDN sends the user information message U.
Send SER_INFO (test cancellation) to the destination terminal.

During the communication operation, the destination terminal which receives the user information message USER_INFO (test cancellation)
The loopback 4 mode of the layer 1 signal control unit 11 is released, "test mode confirmation" is set in the test mode designation information of the "user / user" information element, and "test communication to normal communication" is set in the test / normal switching parameter. Information message USER_IN with "Switch to"
Send FO (confirmation of cancellation).

The calling terminal sends this user information message US
When receiving ER_INFO (confirmation of cancellation), the image information transmitting operation in the normal mode is performed using the information channel established at that time, and the transmitted image information is transmitted to the destination terminal.
At the time of transmitting image information at this time, the window size, packet size, and link timer values are calculated in the same manner as above using the line delay time and bit error rate obtained in the test operation performed previously. And the data transmission operation using the calculated window size, packet size, and link timer value.

When the transmission of the image information is completed, the calling terminal sends a disconnection message DISC to the ISDN to request the release of the information channel, and the ISDN releases the release message REL.
To notify the restoration of the information channel. On the other hand, ISDN sends a disconnection message DISC to request the release of the information channel to the destination terminal, and the destination terminal sends a release message REL to ISDN to notify the restoration of the information channel.

As a result, the calling terminal IS sends the release completion message REL_COMP notifying the completion of the channel disconnection.
In response to the DN, the information channel between the calling terminal and the ISDN is released. At the same time, the ISDN sends a release completion message REL_COMP to the destination terminal,
The information channel between N and the called terminal is released. As a result, the information channel established between the calling terminal and the called terminal is completely released.

In this way, the information channel is set between the calling terminal and the called terminal, the test data transmission is performed, and the test data transmission is followed by the data transmission using the same information channel. Once the data transmission is complete, the information channel is released.

As described above, in this embodiment, the test data transmission and the image information data transmission are continuously performed in the same call, so that the line efficiency is good and the communication cost can be reduced.

10 and 11 show an example of processing at the time of calling.

First, the line quality information corresponding to the ISDN number designated as the destination is fetched from the parameter memory 3 and it is checked whether or not the data indicating "non-connection" is set in the connection / non-connection flag (decision 10).
1). When the result of determination 101 is YES, an error message indicating that the terminal is not connected to the selected partner terminal (ISDN number) is displayed on the operation display unit 6 (process 102), and this operation is performed. To finish.

When the result of judgment 101 is NO,
It is checked whether the operator has set the test communication mode or the transmission mode in which normal transmission is performed after the test communication (decision 103). The result of judgment 103 is YES
, The above-mentioned call setup message SETUP
(Test request) is sent to ISDN to call the other terminal (process 104).

Then, message reception is repeated until the response message CONN is received (process 105,
(NO loop of decision 106), if the response message CONN is received and the result of decision 106 is YES, then it is checked whether or not the above-mentioned response message CONN (test confirmation) is received (decision 107). When the result of the determination 107 is NO, a predetermined disconnection recovery procedure is executed (process 108) and the series of operations is ended.

When the result of the judgment 107 is YES, the B channel test mode is set in the layer 1 signal control section 11 (process 109), and the above-mentioned test data transmitting / receiving operation and the test result are evaluated. (Process 110,
111). Thereby, the transmission delay time and the bit error rate are obtained.

Then, the transmission delay time and the bit error rate obtained at that time are respectively set in the transmission delay information and the bit error rate information of the line quality information of the partner terminal,
The line quality information is stored in the parameter memory 3. At the same time, the list information of the transmission delay information and the bit error rate information is displayed on the operation display unit 6 and is recorded and output from the plotter 5 (process 112).

Then, at that time, it is checked whether or not the transmission mode in which the normal transmission is performed after the test communication is designated by the operator (decision 113). When the result of the judgment 113 is NO, the process proceeds to step 108, The call is disconnected and recovered, and the series of operations ends.

When the result of judgment 113 is YES, the window size, the packet size, the packet size,
Also, the optimum value of the link timer value is calculated, set in the window size information, the packet size information, and the link timer value information of the line quality information and stored in the parameter memory 3, and at the same time B is used at that time.
The values of those communication parameters are set in the channel transmission control units 13 and 14 (process 114).

Then, the B channel test mode of the layer 1 signal control section 11 is released (process 115), the above-mentioned user information USER_INFO (test release) is sent out (process 116), and a message is received (process 117). ..

The received message is the user information USER
Whether or not _INFO (confirmation of cancellation) is checked (decision 118), and when the result of the decision 118 is NO, it means that data transmission in the normal mode cannot be performed, so the process 10
8, the call is disconnected and recovered, and the series of operations is completed.

When the result of judgment 118 is YES, the data transmission operation using the information channel established at that time is performed (process 119) and the transmission image information is transmitted to the partner terminal.

When the image information transmitting operation is normally completed (the result of the determination 120 is YES), the process proceeds to step 108, the call is disconnected and recovered, and the series of operations is completed. Also,
If the image information transmission operation does not end normally (determination 120
Is NO), it is checked whether the partner terminal can shift to the test mode (decision 121).

When the result of the judgment 121 is YES, "test mode request" is set in the test mode specification information of the "user / user" information element, and "test / normal switching parameter is set from" normal communication to test communication ". User information message USER_IN with "switch" set
FO (test request) is transmitted (process 122).

Then, the message is received (process 12
3), the received message is "user user"
"Test mode confirmation" is added to the test mode specification information of the information element.
Is set and the test / normal switching parameter is set to "switch from normal communication to test communication", and it is checked whether or not it is a user information message USER_INFO (test confirmation) (decision 124). The result of judgment 124 is N
When it becomes O, the process proceeds to step 108, the call is disconnected and recovered, and the series of operations is ended.

When the result of determination 124 is YES, the B channel test mode is set in layer 1 signal control unit 11 (process 125), the process proceeds to process 110, and the subsequent operations are performed.

When the result of the judgment 121 is NO, it is judged whether or not the partner terminal is connected and the data can be transmitted to and from the partner terminal based on the above-mentioned judgment criteria ( If the result of the determination 126) is YES, the process proceeds to step 108, the call is disconnected and restored, and the series of operations ends. Also, the determination 126
When the result is NO, the data indicating "non-connection" is set in the connection / non-connection flag of the line quality information (process 127), the process proceeds to process 108, the call is disconnected and recovered, and a series of operations. To finish.

If only the transmission operation in the normal mode is set and the result of the judgment 103 is NO,
The call setup procedure operation in the normal mode is performed (process 128),
Then, the process proceeds to step 119 and the subsequent steps are executed to carry out a normal image information transmission operation. However, even in this case, when the result of determination 120 is NO and the result of determination 121 is YES, the operation in the test mode is continued.

12 and 13 show an example of processing when an incoming call is detected.

When an incoming call is detected, the information element of the call setting message SETUP received at that time is analyzed to check whether or not it is possible to connect to the partner terminal (decision 201), and the judgment 2
When the result of 01 is NO, the incoming call is ignored (process 202), and a series of operations ends.

When the result of judgment 201 is YES, it is checked whether or not the message received at that time is the above-mentioned call setup message SETUP (test request) (decision 203). When the result of the determination 203 is YES, the above-mentioned response message CONN (test confirmation)
Is transmitted (process 204).

Then, the message is received (process 20
5) The received message is the response confirmation message C
Check whether it is ONN_ACK (decision 20)
6). When the result of determination 206 is NO, the layer 1 signal control unit 11 is instructed to cancel the loopback 4 mode (process 207), a predetermined call disconnection recovery procedure is executed (process 208), and a series of operations is ended. To do.

When the result of the judgment 206 is YES, the loopback 4 mode setting is instructed to the layer 1 signal control section 11 (process 208). In that state, the process waits until a message is received (process 210).

It is checked whether the received message is the above-mentioned user information message USER_INFO (test cancellation) (decision 211), and the result of the decision 211 is N.
When it becomes O, the processing shifts to step 207, the loopback 4 mode cancellation is instructed to the layer 1 signal control section 11, the call is disconnected and recovered, and the series of operations is ended.

When the result of the judgment 211 is YES, the above-mentioned user information message USER_INFO.
(Release confirmation) is sent (process 212), and the layer 1 signal control unit 11 is instructed to release the loopback 4 mode (process 213).

Next, the image information transmission operation using the established information channel is performed (process 214). When this image information transmission operation is completed, a message is received (process 21
5) It is checked whether the received message is a call disconnection recovery message (decision 216).

When the result of the judgment 216 is YES, the processing shifts to the processing 207, the layer 1 signal control section 11 is instructed to release the loopback 4 mode, and the call is disconnected and restored.
A series of operations ends.

When the result of judgment 216 is NO,
The received message is the user information message U described above.
It is checked whether or not it is SER_INFO (test request) (decision 217), and when the result of decision 217 is NO, the process proceeds to step 207, and the layer 1 signal control unit 11 is instructed to cancel the loopback 4 mode, Disconnect and recover
A series of operations ends.

When the result of judgment 217 is YES, the layer 1 signal control unit 11 is instructed to set the loopback 4 mode (process 218) and the above-mentioned user information message USER_INFO (test confirmation) is sent out (process 219). ), The process proceeds to step 210 and the subsequent operations are performed.

In addition, the call setup message SE in the normal mode
When the TUP is received and the result of the determination 203 is NO, the response message CONN is transmitted (process 2).
20), the message is received (process 221). It is checked whether or not the received message is the response confirmation message CONN_ACK (decision 222), and when the result of the decision 222 is YES, the process proceeds to step 214 and the subsequent operations are performed. Further, when the result of the determination 222 is NO, the processing shifts to the processing 207, the loopback 4 mode cancellation is instructed to the layer 1 signal control section 11, the call is disconnected and recovered, and the series of operations is ended.

In this way, since the data transmission in the normal mode and the test communication can be alternately repeated, the degree of freedom in using the test communication is increased and the usability is improved.

By the way, in the above-mentioned embodiment, the operation mode of the test communication is set by using the "user-user" information element. However, the call setting message SETU is set.
"Calling subaddress" information element of P, "Calling subaddress"
Information Element, "Lower Layer Consistency" Information Element, and
The “higher layer compatibility” information element may be used to set the operation mode of the test communication. However, in this case, the operation of only the test communication can be designated from the calling terminal, and the operation of performing the normal communication after the test communication cannot be performed.

Although the present invention is applied to the group 4 facsimile apparatus in the above-described embodiments, the present invention can be applied to other ISDN terminal apparatuses in the same manner.

Further, the signal format of the test data, the contents of the line quality information, the type of communication parameters depending on the line quality, the method of calculating the communication parameters, etc. are not limited to those shown in the above-mentioned embodiment.

[0112]

As described above, according to the present invention,
The test for measuring the line quality can be performed by the ISDN terminal alone, and the cost required for measuring the line quality can be greatly reduced. Further, if a test for measuring the line quality is performed subsequent to the normal data transmission, the test for measuring the line quality is performed only with a partner terminal that needs the communication, so that the communication cost can be reduced. Further, since the values of the communication parameters depending on the line quality are set according to the measured line quality, optimum values are set for these communication parameters, and the effect of improving the efficiency of data transmission can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a group 4 facsimile apparatus according to an embodiment of the present invention.

FIG. 2 is a time chart showing an example of a call setup / call release procedure in ISDN.

FIG. 3 is a schematic diagram showing an example of a signal format of a call setup message and information elements of the call setup message SETUP.

FIG. 4 is a schematic diagram showing an example of a “user-user” information element.

FIG. 5 is a time chart showing a procedure example during test communication.

FIG. 6 is a block diagram for explaining an operation during test communication.

FIG. 7 is a schematic diagram for explaining a test operation.

FIG. 8 is a schematic diagram showing an example of line quality information.

FIG. 9 is a time chart showing a procedure example when normal communication is performed after test communication.

FIG. 10 is a flowchart showing a part of a processing example of the calling terminal.

FIG. 11 is a flowchart showing the remaining part of the processing example of the calling terminal.

FIG. 12 is a flowchart showing a part of a processing example of a destination terminal.

FIG. 13 is a flowchart showing the remaining part of the processing example of the destination terminal.

Claims (9)

[Claims] 1. ISDN using ISDN as a transmission path
In the line quality test method for terminal equipment, the test terminal makes a call to the terminal under test with information indicating that a loopback mode test is to be added to the call setup message, and the terminal under test receives the incoming call when it detects an incoming call. If information indicating that a loopback mode test is to be performed is added to the call setup message, the message that responds during the call setup procedure to confirm that the test is being performed is added to the information channel. Set the loopback mode in which the received data is directly looped back as the transmitted data above, and the test terminal, when the information received to confirm the test execution is added to the message received from the terminal under test, establishes the prescribed test after establishing the information channel. Pattern data is sent out, and based on the reception result of the test pattern data,
A line quality test method for an ISDN terminal device, characterized in that the quality of a line set up with the terminal under test is judged. 2. ISDN using ISDN as a transmission line
In the line quality test method for terminal equipment, the test terminal makes a call to the terminal under test with information indicating that a loopback mode test is to be added to the call setup message, and the terminal under test receives the incoming call when it detects an incoming call. If information indicating that a loopback mode test is to be performed is added to the call setup message, the message that responds during the call setup procedure to confirm that the test is being performed is added to the information channel. Set the loopback mode in which the received data is directly looped back as the transmitted data above, and the test terminal, when the information received to confirm the test execution is added to the message received from the terminal under test, establishes the prescribed test after establishing the information channel. Pattern data is sent out, and based on the reception result of the test pattern data,
A line quality test method for an ISDN terminal device, characterized in that the quality of a line established with the terminal under test is judged and the judgment result is displayed and output. 3. ISDN using ISDN as a transmission line
In the line quality test method for terminal equipment, when the normal mode data transmission does not end normally, the transmitting terminal shall add the information indicating that the loopback mode test is to be performed to the call setup message to the terminal under test. When the terminal under test makes a call again and the call setup message received when the incoming call is detected has information indicating that a loopback mode test is to be performed, the terminal under test shall execute that test in the response message during the call setup procedure. In addition to adding information indicating confirmation, a loopback mode is set in which the received data is directly looped back as transmission data on the information channel, and the test terminal adds information indicating test execution confirmation to the message received from the terminal under test. When the information channel is established, the prescribed test pattern data is transmitted and the test is performed. Based on the reception result of the use pattern data,
A line quality test method for an ISDN terminal device, characterized in that the quality of a line established with the terminal under test is judged and the judgment result is displayed and output. 4. The information indicating that a loopback mode test to be added to the call setup message is performed is a user / user information element, a calling subaddress information element, a called subaddress information element, a lower layer compatibility information element, or The line quality test method for an ISDN terminal device according to claim 1, 2, or 3, wherein any one of the higher layer compatibility information elements is used. 5. The test terminal sets and saves various parameter values depending on communication quality during data transmission when the terminal under test is a destination terminal, based on the line quality determination result, The ISDN terminal according to claim 1, 2 or 3, wherein at the time of data transmission, the values of the various parameters stored corresponding to the destination terminal at that time are set at the time of the data transmission. Equipment line quality test method. 6. ISDN using ISDN as a transmission line
In the line quality test method for terminal equipment, when data transmission in normal mode does not end normally, the transmitting terminal, with the call held, adds user information with information indicating that a loopback mode test is to be performed. When a message is sent to the receiving terminal, and the receiving terminal receives the user information message with the information indicating that the loopback mode test is performed during the data transmission operation, the receiving terminal displays the information that confirms the execution of the test. A user who responds to the added user information message to the sending terminal and sets a loopback mode in which the received data is directly looped back as the sending data on the information channel, and the sending terminal is the user who has added the information indicating the test execution confirmation from the receiving terminal. When an information message is received, the prescribed test pattern data is sent and Based on the reception result of the test pattern data, line quality test method ISDN terminal device determines the quality of the tensioned line between the reception terminal, and displaying outputs the determination result. 7. An ISDN using ISDN as a transmission line
In the line quality test method for terminal equipment, when data transmission in normal mode does not end normally, the transmitting terminal, with the call held, adds user information with information indicating that a loopback mode test is to be performed. When a message is sent to the receiving terminal, and the receiving terminal receives the user information message with the information indicating that the loopback mode test is performed during the data transmission operation, the receiving terminal displays the information that confirms the execution of the test. A user who responds to the added user information message to the sending terminal and sets a loopback mode in which the received data is directly looped back as the sending data on the information channel, and the sending terminal is the user who has added the information indicating the test execution confirmation from the receiving terminal. When an information message is received, the prescribed test pattern data is sent and Based on the reception result of the trial pattern data, the quality of the line set up with the receiving terminal is judged, the judgment result is displayed and output, and the information indicating the cancellation of the test in loopback mode is added. Sends a user information message to the receiving terminal, and when the receiving terminal receives the user information message with the information indicating the cancellation of the loopback mode test, it indicates that the loopback mode is canceled and the cancellation of the loopback mode is confirmed. In response to the user information message with the added information to the sending terminal, the mode is transferred to the normal data transmission mode, and when the sending terminal receives the user information message with the information indicating confirmation of the release of the loopback mode, the normal data transmission is performed. Quality test method for ISDN terminal equipment, characterized in that transmission data is transmitted in a mode . 8. The transmission terminal sets and saves various parameter values depending on the communication quality at the time of data transmission when the reception terminal is the destination terminal, based on the line quality judgment result, and stores the data. 9. The ISDN terminal device according to claim 6, 7 or 8, wherein at the time of transmission, the values of the various parameters stored corresponding to the destination terminal at that time are set at the time of data transmission. Line quality test method. 9. An ISDN using ISDN as a transmission line
In the terminal device control method, when the normal mode data transmission does not end normally and the reason why it does not end normally is the non-connection of the partner terminal, save the information indicating the non-connection of the receiving terminal at that time On the other hand, when the information indicating the non-connection of the terminal is stored for the other terminal specified when the call is made, it is determined that the other terminal selection at that time is an error operation, and a message to that effect is displayed and the processing ends in error. A method for controlling an ISDN terminal device, comprising: