JP2011120014A - Communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To implement accurate band control by a gatekeeper device by performing band allocation while considering bands to be used by a redundant packet when a redundant packet scheme is adopted as an error correcting scheme. <P>SOLUTION: A communication apparatus including an error correcting unit for performing error correction using a redundant packet during communication further includes: a real communication band calculating unit for calculating a communication band including the redundant packet when performing error correction using the redundant packet by the error correction unit; and a re-allocation requesting unit for transmitting a re-allocation request of the communication band to a gatekeeper device within the band calculated by the real communication band calculating unit. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a communication device, and more particularly to a communication device having a function of performing error correction using redundant packets.

  In general, for example, ITU-T recommendation T.I. There are communication apparatuses that perform error correction using redundant packets, such as a facsimile apparatus and a gateway apparatus that perform communication defined in FIG.

  In addition, for the purpose of realizing real-time network facsimile communication at a communication speed set between the facsimile apparatus and the partner terminal apparatus, when the necessary network bandwidth is wider than the allocated network bandwidth, the dummy facsimile apparatus on the transmission side is dummy. A facsimile apparatus is known that transmits a training failure signal of 1 or less so that the bandwidth is equal to or less than the allocated network bandwidth from the gatekeeper apparatus (see, for example, Patent Document 1).

  However, for example, T.W. When an error correction method using redundant packets is adopted in communication using UDP (user datagram protocol) as a 38 transport, the redundant packets use more bandwidth than the bandwidth allocated by the gatekeeper device. However, there is a problem that accurate bandwidth control cannot be performed.

  In addition, the above-mentioned Patent Document 1 is for making the network bandwidth to be used equal to or less than the allocated network bandwidth. When the redundant packet method is adopted as the error correction method, the bandwidth based on the redundant bandwidth is used. It was not even taken into account to make the assignment.

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a communication device capable of realizing accurate bandwidth control by a gatekeeper device based on the bandwidth used by redundant packets.

  In order to achieve this object, a communication apparatus according to the present invention is a communication apparatus that is used in a communication system including a gatekeeper device and includes error correction means that performs error correction in communication using redundant packets. When performing error correction using redundant packets by the error correction means, the actual communication bandwidth calculating means for calculating the communication bandwidth including the redundant packets, and the bandwidth calculated by the actual communication bandwidth calculating means, Reassignment requesting means for transmitting a communication band reassignment request to the gatekeeper device.

  The communication apparatus according to the present invention is a communication apparatus that is used in a communication system including a gatekeeper device and includes error correction means for performing error correction in communication using redundant packets. When error correction is performed using a redundant packet, an actual communication band calculation unit that calculates a communication band including the redundant packet, and a band calculated by the actual communication band calculation unit are transmitted to a communication partner device using DCS (Telephone data -Carrier System) and a notification means for notification.

  The communication apparatus according to the present invention is a communication apparatus that is used in a communication system including a gatekeeper device and includes error correction means for performing error correction in communication using redundant packets. When error correction is performed using a redundant packet, an actual communication band calculation unit that calculates a communication band including the redundant packet, and the band calculated by the actual communication band calculation unit, the predetermined communication connection procedure And an initial transmission means for transmitting an initial bandwidth allocation request to the gatekeeper device.

  As described above, according to the present invention, accurate bandwidth control by the gatekeeper device can be realized based on the bandwidth used by redundant packets.

It is a block diagram which shows the system configuration example using embodiment of this invention. It is a block diagram which shows the hardware structural example of this embodiment. It is a block diagram which shows the functional structural example of this embodiment. It is a figure explaining a redundant packet system. T.A. It is a sequence diagram which shows the transmission / reception signal between 38 terminals and a gatekeeper apparatus. It is a flowchart which shows the 1st operation example by this embodiment. It is a flowchart which shows the 2nd operation example by this embodiment. It is a flowchart which shows the 3rd operation example by this embodiment. It is a flowchart which shows the 4th operation example by this embodiment. It is a sequence diagram which shows the resending operation | movement of the zone | band request | requirement by the 4th operation example. It is a flowchart which shows the 5th operation example by this embodiment. It is a flowchart which shows the 6th operation example by this embodiment. It is a flowchart which shows the 7th operation example by this embodiment. It is a flowchart which shows the 8th operation example by this embodiment.

  Next, the communication apparatus according to the present invention is referred to as ITU-T recommendation T.30. 38 for performing communication defined in FIG. One embodiment applied to a 38 terminal device will be described in detail with reference to the drawings.

First, an outline of the present embodiment will be described.
In this embodiment, in the communication for performing the bandwidth control using the gatekeeper, the bandwidth actually used in the actual communication is increased by using the redundant packet with respect to the bandwidth allocated from the gatekeeper in advance. Is found, a bandwidth reassignment request is made to the gatekeeper in consideration of a bandwidth that increases due to redundant packets.

Next, a system configuration using this embodiment will be described.
In FIG. A system configuration in the case where communication is performed with a communication partner apparatus using a 38 terminal apparatus is shown.

  The G3 fax machine 40a, which is the G3 facsimile apparatus on the transmission side, transmits the transmission side T.264 via the telephone network 50a. A destination is specified by calling a gateway device (GW) 1a as a 38-terminal device.

  Sender T. The network facsimile apparatus (IAF) 20a as the 38 terminal apparatus directly receives the destination designation from the operation unit or the like of the own apparatus.

  Sender T. Prior to the start of communication via the packet network 60a, the GW 1a or the IAF 20a serving as the 38 terminal device issues a network bandwidth allocation request to the gatekeeper device 30a and receives the network bandwidth allocation from the gatekeeper device 30a. Note that the gatekeeper devices 30a and 30b are the same as those of the T.W. It is a server device that performs address resolution and bandwidth control among 38 terminals.

Next, the hardware configuration of the present embodiment will be described with reference to FIG.
T. of this embodiment. The 38 terminal includes a system control unit 2, ROM 3, RAM 4, storage device 5, operation port 6, LAN controller 7, transformer 8, modem 9, network control unit 10, and system bus 11.

The system control unit 2 is a microcomputer that controls each unit of the apparatus while using the RAM 4 as a work area in accordance with a control program written in the ROM 3.
As described above, the ROM 3 is a read-only memory in which a control program for the system control unit 2 to control each unit of the apparatus is stored. The RAM 4 is a random access memory used as a work area for the system control unit 2 as described above.

  The storage device 5 is composed of a hard disk device or the like, and is for accumulating data. The operation display unit 6 is for receiving an operation state display of the apparatus and various operation inputs. The LAN controller 10 decodes data received from the packet network 60 via the transformer 8, encodes data to be transmitted to the packet network 60, and buffers a transmission frame and a reception frame to thereby transmit the packet network 60. Control the LAN protocol via the transformer 8, which is a transformer for transmitting and receiving data from the system, and the system control unit 2 controls the TCP / IP (Transmission Control Protocol / Internet Protocol) protocol on the LAN protocol, ITU-T recommendation This is to enable real-time network facsimile communication based on H.38.

  The modem 9 is a G3 facsimile modem that modulates data transmitted to the telephone network 50 via the network control unit 10 and demodulates signals received from the telephone network 50 via the network control unit 10. The modem 9 also transmits a DTMF signal corresponding to the destination number.

  The network control unit 10 is connected to the telephone network 50, detects the polarity reversal of the line of the telephone network 50, closes / releases the DC loop of the line, detects line release, detects the dial tone, busy tone, etc. Connection control with a line such as signal detection and ringing signal detection, and transmission of a selection signal corresponding to a destination number by a dial pulse signal corresponding to a 20 PPS or 10 PPS dial line are performed. The system bus 11 is a signal line for the above units to exchange data.

  Next, a configuration as each functional part realized by the hardware configuration described above will be described with reference to FIG.

T.A. The 38 communication control unit generates a packet necessary for communication (T.38) with the counterpart terminal.
The gatekeeper communication control unit generates a packet necessary for communication (RAS) with the gatekeeper.

The network transmission control unit transmits and receives various packets to the packet network.
The call control communication control unit generates a packet necessary for communication (Q.931, H.245, etc.) with the counterpart terminal.

The transmission control instruction part The 38 communication control unit and the gatekeeper communication control unit are instructed to generate respective communication packets as necessary.
The actual communication band calculation means calculates a communication band considering redundant packets.
The communication band reallocation request means instructs the gatekeeper communication control unit to generate a packet to be transmitted as a band allocation request.

The timer control unit performs various timer controls.
The redundant packet number changing means is responsive to an instruction from the transmission control unit in accordance with the T.D. The number of secondary packets (redundant packets) to be added in 38 packets is changed.
T.A. 38 communication band changing means, according to an instruction from the transmission control unit, T.38. The 38 communication band is changed.

  Next, the redundant packet method that can be selected as the error correction method according to the present embodiment will be described with reference to FIG.

  The redundant packet method is a mechanism in which a packet previously transmitted as a primary packet is added as a secondary packet and transmitted. When the number of redundant packets is 2, the primary packet with sequence number 4 and the primary packet with sequence number 2 are added to the primary packet with sequence number 4 as secondary packets.

Next, the operation of this embodiment will be described.
First, T.W. A description will be given of the exchange of signals regarding bandwidth requests and the like between the 38 terminals and the gatekeeper device with reference to the sequence diagram of FIG.

  T.A. The 38 terminals make a request for the used communication band to the gatekeeper by ARQ (communication start request), and if the gatekeeper can accept in the requested band, the communication terminal allocates the communication band by ACF (communication start confirmation).

  Thereafter, the T.P. 38 transport protocol is determined, When the 38 transport protocol is UDP, an error correction method is determined.

  To change the bandwidth during communication, see T.M. The 38 terminals make a communication band change request to the gatekeeper device by BRQ (band change request). When the gatekeeper device can accept the requested bandwidth, the gatekeeper device assigns the changed communication bandwidth by BCF (bandwidth change confirmation).

FIG. 6 shows a flowchart of the first operation example.
T.A. When the 38 transport is UDP and the error recovery method is the redundant packet method (steps A1 and A2), the communication band considering the redundant packet is calculated. The communication band considering the redundant packet is obtained by multiplying the communication band agreed upon between the terminals by “the number of redundant packets + 1” (step A3).
Using the calculated communication band, a band change request is transmitted to the gatekeeper device by the band change sequence shown in FIG. 5, and an allocation request is made at the time of band (step A4).

As described above, the T.I. The 38 terminal has the following features.
In a system that performs bandwidth control using a gatekeeper, 38 transport protocol is UDP, When the error recovery method determined by the 38 protocol is a redundant packet method, communication is made to the gatekeeper by means of an actual communication band calculating unit that calculates a communication band considering redundant packets and a band calculated by the actual communication band calculating unit. And a communication band reallocation request means for executing a band reallocation request.

  In the conventional machine, T.W. When the error correction method using redundant packets is adopted in communication using UDP as 38 transport, the bandwidth actually used is greatly increased compared to the bandwidth allocated by the gatekeeper, and accurate bandwidth control is achieved. There was a problem that could not be issued.

On the other hand, in the present embodiment, as described above, a bandwidth necessary for communication is determined by an error recovery method determined by negotiation with a communication partner, and reallocation is performed as necessary.
For this reason, according to this embodiment, T.I. Even when an error correction method using redundant packets is adopted in communication using UDP as 38 transport, accurate band control can be performed.

  For this reason, according to the present embodiment, communication can be performed in a band that falls within the communication band allocated by the gatekeeper. The bandwidth control method can be provided in consideration of redundant packets in the real-time facsimile gateway defined in FIG.

Next, a second operation example according to the present embodiment will be described with reference to FIG.
In this second operation example, first, a bandwidth reassignment request is made to the gatekeeper by the same operation as in steps A1 to A4 of the first operation example described above (steps B1 to B4), and the response from the gatekeeper device Is received (step B5), and if the allocated bandwidth is smaller than the requested bandwidth (step B6), the number of redundant packets is reduced and the T.P. 38 packets are created and transmitted (step B7).

As described above, the above-described embodiment has the following features.
After the bandwidth reassignment request according to the first operation example described above, further comprising redundant packet number changing means for reducing the number of redundant packets when the communication bandwidth allocated by the gatekeeper is smaller than the requested communication bandwidth. Features.

According to said characteristic, the following effects are acquired.
Even when the communication band assigned by the gatekeeper is smaller than the communication band that is actually used, communication can be performed within the range of the communication band managed by the gatekeeper.
This is because the communication band to be used can be reduced by reducing the number of redundant packets.

Next, a third operation example according to the present embodiment will be described with reference to FIG.
In the third operation example, first, a bandwidth reassignment request is made to the gatekeeper by the same operation as steps B1 to B6 in the second operation example described above, and the assigned bandwidth is smaller than the requested bandwidth. In the case (steps C1 to C6), the communication band (ACF) allocated at the beginning of communication is compared with the communication band (BCF) allocated after the reallocation request (step C7). From this comparison, when the allocated bandwidth in the BCF is smaller than the allocated bandwidth in the ACF, even when no redundant packet is added, it is determined that the communication bandwidth allocated by the gatekeeper is exceeded, and the communication is disconnected. Thereafter, communication is performed again after a predetermined time (step C9).

  As a result of the comparison in step C7, when the allocated bandwidth in the BCF is equal to or larger than the allocated bandwidth in the ACF, the number of redundant packets is reduced and the T.P. 38 packets are created and transmitted (step C8).

As described above, the above-described embodiment has the following features.
After the bandwidth reassignment request according to the second operation example described above, if the communication bandwidth assigned by the gatekeeper is smaller than the communication bandwidth assigned at the start of communication, the communication is disconnected and communication is resumed after a predetermined time. carry out.

According to said characteristic, the following effects are acquired.
Even when the communication band assigned by the gatekeeper is smaller than the communication band actually used, communication can be performed without exceeding the communication band managed by the gatekeeper.

  This is because the communication can be performed without exceeding the range of the communication band managed by the gatekeeper by performing the communication again after a predetermined time without performing the communication.

Next, a fourth operation example according to the present embodiment will be described with reference to FIG.
In the fourth operation example, first, a bandwidth reassignment request is made to the gatekeeper by the same operation as steps B1 to B6 in the second operation example described above, and the assigned bandwidth is smaller than the requested bandwidth. In the case (steps D1 to D6), after the communication is disconnected, retransmission is performed after a predetermined time (step D7).

FIG. 10 shows a sequence diagram of the fourth operation example.
As a result of transmitting a communication band reassignment request (BRQ) to the gatekeeper, when a response of assignment rejection (BRJ) is received from the gatekeeper, the transmission control instruction unit sets a retransmission interval time in the timer control unit. After the set interval time elapses, a timer notification is sent from the timer control unit to the transmission control instruction unit, and the connection request is performed again using this as a trigger.
Note that the retransmission interval is fixed in advance in the device of the present embodiment, but may be configured such that the user can arbitrarily change the setting.

As described above, the above-described embodiment has the following features.
After the bandwidth reassignment request according to the second operation example described above, if the communication bandwidth assigned by the gatekeeper is smaller than the requested communication bandwidth, the communication is cut off and the communication is performed again after a predetermined time.

According to said characteristic, the following effects are acquired.
Even when the communication band assigned by the gatekeeper is smaller than the communication band actually used, communication can be performed without exceeding the communication band managed by the gatekeeper.

  This is because the communication can be performed without exceeding the range of the communication band managed by the gatekeeper by performing the communication again after a predetermined time without performing the communication.

Next, a fifth operation example according to the present embodiment will be described with reference to FIG.
In this fifth operation example, first, a bandwidth reassignment request is made to the gatekeeper by the same operation as steps B1 to B6 of the second operation example described above, and the allocated bandwidth is smaller than the requested bandwidth. In the case (steps E1 to E6), T. The 38 transport is switched to TCP (Transmission Control Protocol) and retransmitted (step E7).
In the case of communication using TCP, retransmission control in the event of an error is supported by the TCP protocol. There is no need to add to the 38 protocol. For this reason, the communication band does not increase.

As described above, the above-described embodiment has the following features.
After the bandwidth reassignment request according to the second operation example described above, if the communication bandwidth allocated by the gatekeeper is smaller than the requested communication bandwidth, the communication is once disconnected and The 38 transport is switched to an error correction method that does not use redundant packets such as TCP, and communication is performed again.

According to said characteristic, the following effects are acquired.
Even when the communication band assigned by the gatekeeper is smaller than the communication band actually used, communication can be performed within the range of the communication band managed by the gatekeeper.

  The reason is that the communication is not performed and the T.P. This is because the communication can be performed without exceeding the range of the communication band managed by the gatekeeper by switching the 38 transport to an error correction method that does not use redundant packets such as TCP and performing communication again.

Next, a sixth operation example according to the present embodiment will be described with reference to FIG.
In the sixth operation example, first, a bandwidth reassignment request is made to the gatekeeper by the same operation as steps B1 to B6 in the second operation example described above, and the assigned bandwidth is smaller than the requested bandwidth. In the case (steps F1 to F6), after disconnecting the communication, the error recovery method is switched to FEC (Forward Error Correction), and retransmission is performed (step F7).
When the error recovery method is implemented by FEC, an increase in communication bandwidth can be suppressed as compared with the redundant packet method.

As described above, the above-described embodiment has the following features.
After the bandwidth reassignment request according to the second operation example described above, if the communication bandwidth allocated by the gatekeeper is smaller than the requested communication bandwidth, the communication is once disconnected, and then the error recovery method is switched to FEC and communication is performed again. To implement.

According to said characteristic, the following effects are acquired.
Even when the communication band assigned by the gatekeeper is smaller than the communication band that is actually used, communication can be performed within the range of the communication band managed by the gatekeeper.

  The reason is that the communication can be performed without exceeding the range of the communication band managed by the gatekeeper by performing the communication again by switching the error recovery method to FEC without performing the communication. is there.

Next, a seventh operation example according to the present embodiment will be described with reference to FIG.
T.A. When the 38 transport is UDP and the error recovery method is the redundant packet method (steps G1 and G2), the communication band considering the redundant packet is calculated. The communication band considering the redundant packet is obtained by dividing the communication band agreed upon between the terminals by “the number of redundant packets + 1” (step G3).

  By assigning the calculated communication band to the communication band notified to the other terminal by DCS (Telephone data-Carrier System), the upper limit of the communication band in FAX communication can be changed to a low value. Communication can be performed within a range not exceeding the communication band (step G4).

As described above, the T.I. The 38 terminal has the following features.
In a system that performs bandwidth control using a gatekeeper, 38 transport protocol is UDP, When the error recovery method determined by the 38 protocol is a redundant packet method, the actual communication bandwidth calculating means for calculating the communication bandwidth in consideration of the redundant packet and the bandwidth calculated by the actual communication bandwidth calculating means Change the communication speed. 38 communication band changing means.

  According to said characteristic, since the same effect as the 1st operation example mentioned above is acquired, it can communicate in the zone | band which falls within the communication zone | band allocated from the gatekeeper.

  The reason is that communication can be performed in a band that falls within the communication band allocated by the gatekeeper by reducing the communication speed with the counterpart terminal in consideration of the amount of increase in bandwidth for redundant packets. .

Next, an eighth operation example according to the present embodiment will be described with reference to FIG.
Before transmitting a communication start request (ARQ) to the gatekeeper before starting communication, a communication band considering the number of redundant packets is calculated, and a communication start request is made in the calculated communication band (steps H1 and H2).
The communication band considering redundant packets is obtained by multiplying the maximum band in which the own device can perform communication by “the number of redundant packets + 1”.

As described above, the T.I. The 38 terminal has the following features.
In a system that performs bandwidth control using a gatekeeper, when making a bandwidth connection request to the gatekeeper for the first time during communication connection according to the communication connection procedure specified in the standard, the bandwidth is allocated in consideration of the number of redundant packets. It is characterized by making a request.

According to said characteristic, since the same effect as the 1st operation example mentioned above is acquired, it can communicate in the zone | band which falls within the communication zone | band allocated from the gatekeeper.
The reason is that it is possible to secure a communication band that takes into account redundant packets in advance.

  Each of the above-described embodiments is a preferred embodiment of the present invention, and the present invention is not limited to this, and various modifications can be made based on the technical idea of the present invention.

For example, by recording a processing procedure for realizing the communication apparatus as the above-described embodiment on a recording medium as a program, the above-described functions according to each embodiment of the present invention can be performed by a program supplied from the recording medium. It can be realized by causing a CPU of a computer constituting the system to perform processing.
In this case, the present invention can be applied even when an information group including a program is supplied to the output device from the above recording medium or from an external recording medium via a network.
That is, the program code itself read from the recording medium realizes the novel function of the present invention, and the recording medium storing the program code and the signal read from the recording medium constitute the present invention. It will be.
As this recording medium, for example, flexible disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, DVD + RW, magnetic tape, non-volatile Sex memory cards, ROM, etc. may be used.

  According to the program according to the present invention, various functions in the above-described embodiments can be realized in various communication devices controlled by the program.

1 Gateway device 2 System control unit 3 ROM
4 RAM
5 Storage Device 6 Operation Port 7 LAN Controller 8 Transformer 9 Modem 10 Network Control Unit 11 System Bus 20 Network Facsimile Device (IAF)
30 Gatekeeper device 40 G3 fax 50 Telephone network

Japanese Patent No. 3907945

Claims (8)

A communication device including an error correction means used in a communication system including a gatekeeper device and performing error correction in communication using redundant packets,
When performing error correction using a redundant packet by the error correction unit, an actual communication band calculation unit that calculates a communication band including the redundant packet;
Reassignment requesting means for transmitting a communication band reassignment request to the gatekeeper device in the bandwidth calculated by the actual communication bandwidth calculating means;
A communication apparatus comprising:   After the reallocation request is transmitted by the reallocation request unit, the number of redundant packets by the error correction unit is reduced when the communication band allocated by the gatekeeper device is smaller than the communication band requested by the reallocation request. 2. The communication apparatus according to claim 1, further comprising a redundant packet number changing means for changing the number of redundant packets.   After the reallocation request is transmitted by the reallocation request means, the communication band allocated from the gatekeeper device is smaller than the communication band requested by the reallocation request, and the allocated communication band is communicated 3. The communication apparatus according to claim 1, further comprising means for disconnecting communication and starting communication again after a predetermined time when the communication band is smaller than the communication band allocated at the start.   After the reallocation request is transmitted by the reallocation request means, if the communication band allocated from the gatekeeper device is smaller than the communication band requested by the reallocation request, the communication is disconnected and communication is performed again after a predetermined time. The communication apparatus according to any one of claims 1 to 3, further comprising means for starting the communication.   After transmitting the reallocation request by the reallocation request unit, if the communication band allocated from the gatekeeper device is smaller than the communication band requested by the reallocation request, the communication is disconnected and the error correction unit 5. The communication apparatus according to claim 1, further comprising means for starting communication again using error correction that does not use redundant packets instead of error correction.   After transmitting the reallocation request by the reallocation request unit, if the communication band allocated from the gatekeeper device is smaller than the communication band requested by the reallocation request, the communication is disconnected and the error correction unit 6. The communication apparatus according to claim 1, further comprising means for starting communication again using error correction by FEC (Forward Error Correction) instead of error correction. A communication device including an error correction means used in a communication system including a gatekeeper device and performing error correction in communication using redundant packets,
When performing error correction using a redundant packet by the error correction unit, an actual communication band calculation unit that calculates a communication band including the redundant packet;
Notification means for notifying the communication partner apparatus of the bandwidth calculated by the actual communication bandwidth calculation means by DCS (Telephone data-Carrier System);
A communication apparatus comprising: A communication device including an error correction means used in a communication system including a gatekeeper device and performing error correction in communication using redundant packets,
When performing error correction using a redundant packet by the error correction unit, an actual communication band calculation unit that calculates a communication band including the redundant packet;
Initial transmission means for transmitting an initial bandwidth allocation request to the gatekeeper device in a predetermined communication connection procedure in the bandwidth calculated by the actual communication bandwidth calculation means;
A communication apparatus comprising:

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