JP2008271340A - Modem communication stabilization system, and modem communication stabilization method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain improvement in quality of modem communication only by providing a probe within a base (local network) and only by simple enhancement obviating a modem communication signal detection circuit for each TA or each switch, regarding a modem communication stabilization system and modem communication stabilization method attaining improvement in quality of modem communication for a terminal within the base connected to an IP network. <P>SOLUTION: A modem communication stabilization system is equipped with a probe and a terminal or a switch. The probe is connected to a network within a base connected to an IP network, monitors a packet with a terminal within the base as a transmitting/receiving destination and transmits, to a terminal of the receiving destination or a switch accommodating the terminal, by setting modem communication to a portion to set a quality status of a packet when the modem communication is detected. When a packet with which the modem communication is set to the portion for the quality status, is received from the probe, the terminal or the switch sets a receiving buffer size large and transmits/receives following packets. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a modem communication stabilization system and a modem communication stabilization method for improving the quality of modem communication of a terminal in a base connected to an IP network.

  Conventionally, when modem communication such as FAX is performed in an IP network, there is an obstacle in performing communication with stable dispersion of packet transmission time (delay jitter) in the IP network. For this reason, a receiving buffer for absorbing delay jitter is provided in the terminal accommodating apparatus (TA), the packet is once retained in the receiving buffer, and the reception information is sent to the CODEC in the TA at regular intervals. There is a technique for improving FAX communication quality.

In addition, a gateway is provided between the IP network and FAX, etc., and a telephone, and during FAX communication, the time limit for storing received packets in the gateway is longer than that for voice calls, and packets are sent to FAX, etc. at regular intervals. By doing so, there is a technique for improving FAX communication quality (Patent Document 1).
JP 2006-121176 A

  In the former technique described above, it is necessary to provide a signal detection circuit for detecting that each TA is a modem communication such as FAX, and in particular, there is a problem that an existing TA such as FAX cannot be used as it is. There is a problem that it is necessary to newly provide a signal detection circuit or the like for detecting that the TA is a modem communication such as FAX.

  In the latter technique described above, a problem arises in that a gateway must be provided between the IP network and each FAX or telephone.

In order to solve these problems, the present invention is a modem communication stabilization system for improving the quality of modem communication of a terminal in a base connected to an IP network, and the network in the base connected to the IP network. The monitoring means for connecting and monitoring voice packets destined for the terminals in the base, and the result of monitoring the packets by the monitoring means, when a voice packet having a pattern indicating modem communication is detected, the modem communication is in effect A probe having quality information transmitting means for transmitting quality state information including information indicating the information to a receiving terminal or a switch accommodating the terminal;
A reception buffer capable of adjusting the capacity and temporarily storing received packets; and receiving quality state information including information indicating that the communication is modem communication from the probe; a reception buffer adjusting means for setting a large reception buffer size; A terminal or a switch having

  At this time, the probe sets the reception buffer size large in the transmission source terminal or the switch that accommodates the transmission source terminal when it is determined from the monitoring result of the packet transmitted / received by the terminal in the base that the duplex communication is performed. Quality state information instructing this is transmitted.

  In addition, the probe is connected to a switch port connected between the IP network and the network in the base, and whether or not the packet having the terminal in the base as the transmission destination or the transmission source is a modem communication is further necessary. Accordingly, whether or not full-duplex communication is performed is monitored.

  Further, when the reception buffer size is set to be large, the terminal or the switch receives the packet while keeping the same size until the communication by the voice packet with the transmission source is completed.

  In the present invention, a probe is connected to a base (local network) connected to an IP network, and the probe monitors a packet in the base to perform modem communication such as FAX (FAX communication (image), modem communication of the embodiment). (The meaning of communication using a modem including (data), etc., the same except for the following embodiments) is detected) Modem communication in the quality information in the packet to the transmission source / destination TA or the switch that supervises the TA The TA or switch that receives the packet with the information added and receives the packet increases the reception buffer size for modem communication, and then transmits and receives the packet, so that only a probe is provided in the base (local network). The modem communication signal detection circuit is not required for each switch, and it is possible to improve the quality of modem communication with only simple improvements. To become.

  The present invention has realized that the quality of modem communication can be improved only by providing a probe in the base (local network) and by making a simple improvement without requiring a modem communication signal detection circuit in each TA or each switch. The present invention is intended to be applied to a system that directly converts voice (PCM) including a modem communication signal into an IP packet, that is, a VOIP system that accommodates modem communication including FAX by a so-called deemed voice method.

FIG. 1 shows a system configuration diagram of the present invention.
In FIG. 1, a base A and a base B are local networks connected to a network (IP network) 31 and are connected via SW12 and SW22, respectively.

  The VOIP server 32 is a well-known server that is connected to the network 31 and controls the base A and the base B to mutually perform voice calls, modem communications, etc. using the IP protocol.

  At the site A, as shown in the figure, a number of IP telephone terminals 13, FAX accommodating terminals A 14, etc. are connected to the SW 12 connected to the network 31. Further, the VOIP probe A11 is connected to a port (monitoring port (mirror port or tap)) of the SW 12 that transmits and receives packets.

  The VOIP probe A11 is connected to the port of the SW12, monitors the packet of the address within the base A as the transmission destination and transmission source, detects modem communication such as FAX, detects full-duplex communication, When the communication or full-duplex communication is detected, a setting indicating that the modem communication or full-duplex communication has been detected is set in the portion indicating the quality state of the packet, and the transmission destination and the transmission source terminal (FAX accommodating terminal A, etc.) To send to.

  The SW 12 is connected between the network 31 and the local network of the base A, and transmits and receives packets in both directions.

  The IP telephone terminal 13 is a telephone that carries out a voice call with a counterpart IP telephone terminal or the like in accordance with an IP protocol (which represents a communication protocol based on IP, the same applies hereinafter).

  The FAX accommodating terminal A14 performs transmission / reception of image signals with a counterpart FAX accommodating terminal according to the IP protocol.

  Similarly, at the base B, as shown in the figure, a number of IP telephone terminals 23, FAX accommodating terminals B24, and the like are connected to the SW 22 connected to the network 31, respectively. Further, the VOIP probe B21 is connected to the port (monitoring port (mirror port or tap)) of the SW 22 that transmits and receives packets.

  The VOIP probe B21 is connected to the port of the SW22, and the destination and the source monitor the packet of the address in the base B, detect modem communication such as FAX, detect full duplex communication, When the communication or full-duplex communication is detected, a setting indicating that the modem communication or full-duplex communication has been detected is set in the portion indicating the quality state of the packet, and the destination and the source terminal (FAX accommodating terminal B, etc.) To send to.

  The SW 22 is connected between the network 31 and the local network of the base B, and transmits and receives packets in both directions.

  The IP telephone terminal 23 is a telephone that performs a voice call with a counterpart IP telephone terminal or the like according to the IP protocol.

  The FAX accommodating terminal B24 transmits / receives image signals to / from the counterpart FAX accommodating terminal according to the IP protocol.

  In order to make the following explanation easy to understand, it is assumed that the illustrated IP address (private address) is assigned to each terminal, probe, etc. in FIG.

Next, the overall operation of the configuration of FIG. 1 will be described according to the order of the flowchart of FIG.
FIG. 2 shows a flowchart (overall) for explaining the operation of the present invention. Here, the case where FAX communication is performed from terminal A (FAX accommodating terminal A14) in base A in FIG. 1 to terminal B (FAX accommodating terminal B24) in base B will be mainly described below. The following description is assumed to have been performed by the VOIP probe B21 unless otherwise specified.

  In FIG. 2, first, communication is started from terminal A to terminal B (S1). As a result, transmission of voice packets from the A direction to the B direction and from the B direction to the A direction starts on the network. This is because, for example, the terminal A in the base A calls the terminal B in the base B, the terminal A in the base A starts communication to the terminal B in the base B, the direction from the terminal A to the terminal B, the terminal B Thus, a bidirectional voice packet in the direction of terminal A is transmitted via the network.

  When this communication is started, the VOIP probe B21 monitors and monitors the voice packet (S2). Here, the VOIP probe B21 connected to the port of the SW22 in the base B on the receiving side is in a state of monitoring packets passing through the SW22.

The following processing is performed according to the signal detected by monitoring.
First, it is determined whether the communication from terminal A to terminal B is completed (S3). In the case of YES, an instruction to return the reception buffer value of the terminal B to the initial value is given in S4 (usually an initial value with a small reception buffer size for voice call), and the process ends. If NO, the process proceeds to S5.

  S5 determines whether the voice packet is information indicating a modem communication start signal. This determines whether or not the VOIP probe B21 of the base 2 in the monitoring state in S2 detects a voice packet indicating a modem communication start signal (for example, a signal of 2100HZ). In the case of YES, it is determined that the modem communication start signal has been detected, so the process proceeds to S6. On the other hand, if a voice packet indicating a CNG signal (for example, a CNG signal is a repetition of a 1100 Hz tone signal as shown in FIG. 8A, a voice packet indicating a 1100 Hz signal) is detected. Proceed to If none is detected, the process returns to S2.

  S21 is processing when it is determined that a CNG signal has been detected in S5, and it is determined whether the destination address of the voice packet to be monitored is within its own base (here, within base B). If YES, the process proceeds to S22.

  That is, it is determined that a fax signal addressed to the terminal at the local site has arrived, and the process of S22, which is a process for that purpose, is performed. On the other hand, NO, that is, it is determined that the destination address is not an address in its own base, and the receiving terminal is determined not to be a terminal in the base B, so nothing is done and the process returns to S2.

  If the destination address of the voice packet to be monitored is within the local site (in this case, the local site B) in S21, the same voice packet has arrived at the terminal within the local site that is the communication destination. (Of course, the format of the voice packet is as shown in (a-1) of FIG. 8).

  In this state, the VOIP probe B21 transmits modem communication monitoring quality information as shown in FIG. 7A to the destination device (terminal) or SW accommodating the destination device in S23 ( S23). That is, the quality information indicating that the quality state is an incoming fax is transmitted to the destination terminal (FAX accommodating terminal B24 in this embodiment).

  Then, the FAX accommodating terminal B24 receives the quality information (of course, the format is as shown in FIG. 7A) (S13). If it is determined that FAX incoming information is included in this information, a process of expanding the reception buffer capacity of the FAX accommodating terminal B is performed.

This process will be supplemented using the explanatory diagram of FIG.
The voice packet is converted into an analog signal by the signal processing unit and transmitted to the terminal as voice information for the analog line.

  On the other hand, in network communication, there is no guarantee of packet continuity and arrival order, and an arrival delay called delay jitter occurs depending on the network conditions.

  That is, when a voice packet coming from the network is directly input to the signal processing unit, there is a risk that voice interruption due to delay jitter occurs. In order to eliminate this, a reception buffer 43 for temporarily storing voice packets is provided, and the signal processing unit reproduces the packets while extracting the packets from the reception buffer 43, thereby reducing voice interruptions.

  However, the reception buffer retains voice packets for a certain period of time, so that a voice delay occurs due to the above-described effect. In a voice call, the speech becomes unnatural due to this voice delay, so it is desirable to reduce the capacity of the reception buffer as much as possible and to shorten the residence time.

  For this reason, in the case of a voice call, it is common to provide a small-capacity reception buffer that recognizes a missing voice due to some delay jitter to the extent that there is no problem with the voice call.

  However, in the case of data communication such as fax and modem communication, a communication error will occur even if there is a slight loss of voice. Conversely, since it is not necessary to consider discomfort in the call, it is desirable that the capacity of the reception buffer is large.

  In the present embodiment, it is assumed that the FAX is capable of voice call. In such a case, the voice buffer capacity is increased in the case of FAX, and the voice buffer capacity is reduced in the case of voice call. Even if this FAX apparatus is used as a VOIP termination apparatus, it is possible to perform communication without a fax error and uncomfortable voice call.

  Next, the process of S6 will be described. Here, it is a process when it is determined in S5 that a 2100 Hz signal has been detected. In this case, the VOIP probe B21 determines whether the transmission address of the voice packet to be monitored is that of the local site side device (an example of the monitoring packet in this embodiment is shown in (b-2) in FIG. 8). If YES, the process proceeds to S11. If NO, the process proceeds to S7.

  S11 is YES in S6, and the transmission address is determined to be within the local site (in this case, the local site is the receiving side (base B)), so the FAX response signal is detected on the receiving side (base B) ((( a-2)) or a response procedure is detected at the receiving side (base B).

  S12 transmits modem communication start quality information to the transmission source device or SW (base B SW) that accommodates the transmission source device (the format of the quality information at this time is shown in FIG. c)).

  As a result, the transmission target (FAX accommodating terminal B24 in this embodiment) receives the quality information from the VOIP probe.

  When the quality information indicates a modem signal, the FAX accommodating terminal B24 that has received this information expands its own reception buffer value (the procedure is the same as that for the CNG signal, and the description is omitted).

  By the above S5 2100 Hz reception, S6 YES, and S11 to S14, the VOIP probe B21 in the site B in FIG. 1 receives the 2100 Hz signal directed to the terminal in the site B, and the transmission address is determined to be in the site B. Since the FAX response signal was detected at the receiving side (base B) ((a-2) in FIG. 8) or the response procedure was detected at the receiving side (base B) ((b-2) in FIG. 8), the terminal Alternatively, the SW that accommodates the terminal sets the quality state of the packet to indicate that the modem communication is received and transmits it, and the terminal that received the packet or the SW that accommodates the terminal has the reception buffer size (the receiving terminal in the base B). (Receive buffer size) is set large for modem communication, and subsequent modem communication can be performed.

  Next, a process when it is determined in S6 that the transmission address is not the local device (the local site is determined to be the transmission side) will be described.

  In this case, the VOIP probe B24 first determines whether the destination address is the local site apparatus. If YES, the process proceeds to S8. In the case of NO, since it is determined that the local site is the transmitting side in S6 and the destination address is not a device in the local site in S7, that is, the destination address is that of a terminal at another site, Return to S2 and wait.

  In S8, voice packet monitoring is continued and it is determined whether 1200 Hz is detected within 100 ms. As shown in (b-2) of FIG. 8, if a signal of 1200 Hz is received within 100 ms following the response signal of 1200 Hz, the ITU-T V. It is determined that the response sequence is 22 bis.

  Here, the VOIP probe A11 in the base A on the transmission side detects. If YES, the process proceeds to S9. In the case of NO, other non-telephone communication processing is performed.

  In S9, the VOIP probe A11 on the transmission side in the site A detects the FAX response signal on the reception side ((a-2) in FIG. 8).

  In S10, the VOIP probe A11 on the transmission side in the base A transmits quality information for starting modem communication to the target device of the destination address in preparation for full-duplex communication ((d) in FIG. 7).

  In step S13, the quality information is received from the VOIP probe A in the site A to the FAX accommodating terminal B24 ((d) in FIG. 7).

Receiving this, the FAX accommodating terminal B24 expands the reception buffer value (see FIG. 9).
The VOIP probe A11 in the site A in FIG. 1 is directed to the terminal in the site A by the above S5 2100 Hz reception, S6 NO, S7 YES, S8 YES, S9, S10, S13, and S14. , The transmission address is determined not to be in the base A, the destination address is a terminal in the base A, and if a 1200 Hz signal is received within 100 ms, the calling side (sending side) base A VOIP probe A11 Sets the quality state of modem communication to the terminal A in the transmission source's own base station and transmits it, and the terminal that received the packet or the SW that accommodates the terminal receives the reception buffer size (the terminal on the transmission side in the base A Alternatively, the receiving buffer size used on the calling side during full-duplex communication of the SW that accommodates the terminal is set large for modem communication, and subsequent modem communication is performed. Ukoto is possible.

  FIG. 3 shows a functional schematic diagram of the VOIP probe of the present invention. This is a functional outline of the VOIP probe A11 at the site A and the VOIP probe B21 at the site B in FIG.

  In FIG. 3, VOIP probes 11 and 21 are used for monitoring network interface 101 to transmit and receive packets to and from the voice communication network.

  The packet quality inspection unit 102 determines FAX communication and modem communication according to the above-described flowchart of FIG. 2 for the packet (packet that has passed through the SWs 12 and 22 in FIG. 1) taken in via the monitoring network interface 101. This is intended to improve the quality of FAX communication and modem communication by setting FAX communication, modem communication, etc. in the packet quality status column and transmitting the data to increase the reception buffer size of the corresponding terminal or SW accommodating the terminal ( Details will be described with reference to FIG. The packet quality inspection unit 102 determines the quality state based on the abnormality from the packet header information in cooperation with the deterioration threshold storage unit 103 and the deterioration communication state management unit 104.

  The log storage unit 105 stores a communication deterioration state log acquired by the deteriorated communication state management unit 104.

  The quality information creation unit 106 creates quality information based on the quality state of the packet communication inspected by the packet quality inspection unit 102.

The transmission group setting storage unit 107 sets and stores a transmission group.
The control network interface 108 transmits and receives packets to and from the control network.

  FIG. 4 shows an operation schematic diagram of the packet quality inspection unit of the present invention. This shows a detailed operation schematic diagram of the quality inspection unit 102 constituting the VOIP probes 11 and 21 of FIG.

  In FIG. 4, the header information in the voice packet is extracted and separated by the voice information extraction unit 41 from the voice information portion. An abnormal state from the header information is determined by the quality state inspection unit 42 in cooperation with the deterioration threshold storage unit 103 having a deterioration determination function and the deterioration communication state management unit 104. The extracted / separated information is inspected by the quality state inspection unit 42 for abnormalities. If there is no abnormality, all 1 is set, and if there is an abnormality, all 0 is set and sent to the PCM pattern mapping unit 43.

  Since the FAX communication is not abnormal in the header information and the quality state inspection unit 42 has no problem, the voice information part is sent to the PCM pattern mapping unit 43.

  The PCM pattern mapping unit 43 develops PCM in time series, and the pattern variation frequency analysis unit 44 checks the pattern variation period. Here, it is detected whether or not frequency components 1100 Hz, 2100 Hz, and 1200 Hz relating to FAX and modem communication are present, and the corresponding frequency components are characteristics at the time of starting FAX and modem communication in time series (characteristics shown in FIG. 8). If so, the quality state inspecting unit 42 notifies the quality information creating unit 106 to create quality information for FAX communication and modem communication.

  Here, the voice packet flowing in the network has been proposed in, for example, IETF RFC1889, and since it is already a de facto standard, the separation of header information and voice information can be easily implemented by diverting existing technology.

  A logical configuration for determining FAX communication and modem communication from voice information in the VOIP probes 11 and 21 will be described in detail with reference to FIG.

  FIG. 5 is a schematic diagram of determination of FAX communication (image) and modem communication (data) of the VOIP probe of the present invention.

  In FIG. 5, for a PCM pattern (a PCM pattern created from a packet by the PCM pattern mapping unit 43 in FIG. 4), the pattern variation frequency analysis unit 44 determines whether or not there is a pattern variation period. Detailed operation is shown in FIG.

  When 1100 Hz is detected, it is determined whether it is 0.5 second on and 3 seconds off ((a-1) in FIG. 8). If YES, it is determined as CNG (calling tone signal), and FAX communication is performed. Is determined. On the other hand, when NO (other than that), another process is performed.

  ・ When 2100 Hz is detected, it is determined whether 2.6 seconds or more and 4 seconds or less are on ((a-2) in FIG. 8). When YES, further OFF off 90 ms (75 ms ± 15 ms) Since it is a CED signal, it is determined as FAX communication. On the other hand, when the answer is YES, 1200 Hz is detected when the OFF duration is 90 ms or less. It is determined that the communication is 22bis modem, and if NO, separate processing is performed.

・ If other cases are detected, separate processing is performed.
Further, when there is no pattern variation period, another process is performed.

As described above, there is a pattern variation for the PCM pattern generated from the voice information of the packet,
・ 1100Hz is O.D. When it is on for 5 seconds and off for 3 seconds, it is CNG (calling tone signal), so it is determined as FAX communication ((a-1) in FIG. 8).
・ If 2100Hz is 2.6 seconds or more and 4 seconds or less is ON and OFF duration is 90 ms or more, it is a CED signal, so it is determined as FAX communication ((a-2) in FIG. 8).
・ When 2100 Hz is on for 2.6 seconds or more and 4 seconds or less, is off for 90 ms or less, and 1200 Hz is detected, V. It can be determined as 22 bis modem communication.

FIG. 6 shows an example of the quality information of the present invention.
FIG. 6A shows a quality information packet format example. Here, the following information shown in the figure is set in the packet.

・ Destination address: Target TA
Source address: VOIP probe Protocol-dependent header:
・ Quality status:
・ Detection direction reception address:
-Detection direction transmission address:
・ Detection time:
・ Other:
Here, the destination address is an address of a destination terminal that transmits a packet in which a quality state is set. The transmission source address is an address of a transmission source that transmits a packet in which a quality state is set, here, an address of a VOIP probe. The protocol-dependent header is a part for setting header information depending on a protocol for transmitting a packet. Here, the quality state is as shown in the definition example of the quality state portion of the packet described in FIG. In the present invention, information for setting the FAX incoming call, modem response, modem call, etc. being defined and transmitting to the target TA (terminal or SW accommodating the terminal) of the destination address to increase the reception buffer size Set. The detection direction reception address is the address of the terminal on the packet reception (response) side. The detection direction transmission address is the address of the terminal on the packet transmission (calling) side.

  FIG. 6B shows a definition example of the quality state in the packet of FIG. In the present invention, in the definition example of the quality state, here, it is set to a part representing FAX communication or modem communication such as FAX incoming call, modem response, modem call, etc., and transmitted to the corresponding terminal to increase the reception buffer size. Set the information for

FIG. 7 shows an example packet of the present invention.
FIG. 7A shows an example (see (a-1) in FIG. 8) in which CNG (base A → base B) is detected by the VOIP probe B. This is because the VOIP probe B at the site B detects the CNG signal (calling tone) of (a-1) in FIG. 8 transmitted from the terminal A at the site A to the terminal B at the site B. When it is determined, the packet is set and transmitted and the reception buffer size of the terminal B is increased. Here, the packet is set as shown below.

-Destination address: 192.168.200.13 (address of terminal B in base B)
Source address: 192.168.200.101 (address of VOIP probe B in site B)
Protocol-dependent header:
-Quality status: FAX incoming-Detection direction reception address: 192.168.100.12 (address of terminal A in site A)
-Detection direction transmission address: 192.168.200.13 (the address of the terminal B in the base B)
As described above, when the CNG signal of (a-1) in FIG. 8 is transmitted from the terminal A in the base A and the VOIP probe B in the base B detects the CNG signal, the above information is set in the packet. Terminal B in the base B with the received destination address 192.168.200.13 (or the SW that accommodates the terminal B) uses its own reception buffer size for FAX incoming (reception). It is possible to set large and improve the quality of FAX communication.

  FIG. 7B shows an example (see FIG. 8A-2) in which the VOIP probe B detects CED (base B → base A). This is because the VOIP probe B at the site B detects the CED signal (response signal) in FIG. 8A-2 that is transmitted from the terminal B at the site B to the terminal A at the site A, and performs FAX communication. When it is determined, the packet is set and transmitted and the reception buffer size of the terminal B is increased. Here, the packet is set as shown below.

-Destination address: 192.168.200.13 (address of terminal B in base B)
Source address: 192.168.200.101 (address of VOIP probe B in site B)
Protocol-dependent header:
・ Quality state: Modem response ・ Reception direction receiving address: 192.168.200.13 (address of terminal B in base B)
-Detection direction transmission address: 192.168.100.12 (address of terminal A in base A)
As described above, when the CED signal (response signal) of (a-2) in FIG. 8 is transmitted as a response from the terminal A in the base B, and the VOIP probe B in the base B detects the CED signal, the packet By setting the above information and transmitting, the terminal B in the base B with the received destination address 192.168.200.13 (or the SW that accommodates the terminal B) sets its reception buffer size as a FAX incoming call. It is possible to set a large value for (reception) and improve the quality of FAX communication.

  (C) in FIG. 7 shows the V.V. An example (see (b-2) of FIG. 8) in which the VOIP probe B detects a 22 bis modem signal is shown. This is because the VOIP probe B at the site B transmits the signal (b-1) in FIG. 8 from the terminal A in the site A to the terminal B in the site B (b-2 in FIG. 8). ) When the response signal (2100Hx is turned on for 2.5 to 4 seconds, off 90 ms or less, and then a response signal of 1200 Hz) is detected and sent as a packet. Then, an example of a packet when increasing the reception buffer size of the terminal B in the base B is shown, and here, it is set as shown below.

-Destination address: 192.168.200.13 (address of terminal B in base B)
Source address: 192.168.200.101 (address of VOIP probe B in site B)
Protocol-dependent header:
・ Quality state: Modem response ・ Reception direction receiving address: 192.168.200.13 (address of terminal B in base B)
-Detection direction transmission address: 192.168.100.12 (address of terminal A in base A)
As described above, in response to (b-1) in FIG. 8 transmitted from the terminal A in the base A, the terminal B in the base B transmits the response signal in (b-2) in FIG. When the VOIP probe B in B detects the CNG signal, the above information is set in the packet and transmitted, so that the terminal B in the base B with the received destination address 192.168.200.13 (or The SW that accommodates the terminal B can set its own reception buffer size large for modem communication (for reception) and improve the quality of modem communication.

  (D) of FIG. 7 is a diagram showing V.V. An example (see (b-2) in FIG. 8) in which the VOIP probe A detects a 22 bis modem signal is shown. In response to the signal (b-1) in FIG. 8 transmitted from the terminal A in the base A to the terminal B in the base B, the terminal B in the base B to the terminal A in the base A When the response signal of (b-2) in FIG. 8 is transmitted as a response, the response signal (2100Hx is turned on for 2.5 to 4 seconds, off 90 ms or less, and then the response signal of 1200 Hz) in the base A When the VOIP probe A detects the packet, the packet is set and transmitted to increase the reception buffer size of the terminal A in the base A. Here, the packet is set as shown below.

-Destination address: 192.168.100.12 (address of terminal A in site A)
Source address: 192.168.100.101 (address of VOIP probe A in site A)
Protocol-dependent header:
・ Quality state: Modem response ・ Reception direction receiving address: 192.168.200.13 (address of terminal B in base B)
-Detection direction transmission address: 192.168.100.12 (address of terminal A in base A)
As described above, when (b-2) in FIG. 8 transmitted as a response from the terminal B in the base B, the VOIP probe A in the base A detects the response signal, the above information is set in the packet. By transmitting, the terminal A (or SW that accommodates the terminal A) in the base A with the received destination address 192.168.100.12 sets its own reception buffer size for full duplex communication (calling side) Large reception), and the quality of full-duplex communication can be improved.

FIG. 8 shows an example of signal exchange at the start of modem communication according to the present invention.
FIG. 8A shows the case of G3 FAX (ITU-T T.30).

  (A-1) of FIG. 8 shows an example of a signal transmitted by the transmission side FAX. Here, as CNG (calling tone signal), a signal of 0.5 seconds on and 3 seconds off at 1100 Hz is repeatedly transmitted.

  (A-2) of FIG. 8 shows an example of a signal transmitted (response transmission) by the reception side FAX. Here, a signal that is on for 2.6 seconds to 4.0 seconds at 2100 Hz is transmitted as a response signal.

  (B) of FIG. An example of a 22 bis response sequence (2400 bps procedure probability using a V.25 response procedure) is shown.

  (B-1) in FIG. 8 shows an example of a signal transmitted by the calling modem (transmitting modem). Here, 1200 Hz is transmitted.

  (B-2) of FIG. 8 shows an example of a signal transmitted by the response side modem (reception side modem) as a response. Here, 2.6 seconds to 4.0 seconds are transmitted at 2100 Hz, 75 ms ± 15 ms (90 ms) off, and then a 1200 Hz signal is transmitted in response.

FIG. 9 is an explanatory diagram for enlarging the size of the reception buffer according to the present invention.
In FIG. 9, a terminal (TA) / SW 41 is a terminal (TA) in a base connected to the network 31 or a SW accommodating the terminal, and here, a reception buffer for temporarily storing received packets. This is an enlargement of the part.

  (1) The received voice packet 42 is sequentially stored on the reception buffer. In the illustrated state, voice packets are sometimes missed due to delay jitter.

  (2) The voice packet stored in the reception buffer 43 can be stored for a time corresponding to the size of the reception buffer 43. Therefore, the size of the reception buffer 43 is increased during the FAX communication (modem communication) than the voice call so that the packet can be temporarily stored for a longer time. The enlargement size is determined in advance by experiments to such an extent that the delay jitter can be absorbed, and the delay jitter (quality) is measured and corrected to an appropriate size during actual operation.

  (3) Voice packets temporarily stored in the reception buffer 43 (stored for a predetermined time) are output from the reception buffer at regular intervals, and are sent to a fax or the like through a signal processing unit.

  FIG. 10 shows a schematic diagram of modem communication detection according to the bit pattern of the present invention. FIG. 10 shows an outline of functions in which the pattern fluctuation frequency analysis unit 44 in FIG. 4 detects a specific period condition from the PCM pattern mapping unit 43.

  (1) One voice packet at the upper left generally includes 20 ms of PCM information. From these, whether or not a bit pattern appears periodically is divided by the reciprocal of the frequency to be detected (sampling period), and the audio payload part is divided, and the respective sampling patterns are compared.

  (2) When the audio payload is divided at a certain period T (ms), 20 / T sampling patterns are formed.

  (3) Numbers are assigned in ascending order of sampling time (1, 2, 3,... [20 / T]) and are represented by S (n). [20 / T] indicates a maximum integer not exceeding 20 / T.

(4) The sampling pattern S (n) is sequentially compared, and if s (n) matches every period T, it can be determined that the signal has a periodicity of T (ms). That is, s (n) = S (n-1)
Is an arbitrary n of 20 / T or less, the original signal is a signal having a period T, that is, a frequency 1 / T.

(5) The following movement is performed in FIG.
(5-1) In order to detect the input PCM pattern in a short time, and in the case where a plurality of frequencies are included at the same time, the PCM pattern is duplicated for the number of investigation targets. For example, if it is desired to detect 2100 Hz, 1200 hz, and 1100 hz, it is necessary to create three types of sampling patterns, so three are duplicated.

(5-2) Divide every period to create a sampling pattern.
(5-3) Compare the sampling patterns before and after the time, and if they match, the result output flag is raised, and the fact that the frequency component is held is sent to the PCM pattern mapping unit 43.

  As described above, by detecting the appearance period of the same PCM pattern instead of converting it into speech once, the presence or absence of a characteristic signal is detected at the start of modem communication as schematically shown in FIG. It becomes possible.

  The present invention stabilizes modem communication by improving the quality of modem communication only by providing a probe in the base (local network) and by simply making improvements without requiring a modem communication signal detection circuit in each terminal (TA) or each switch. And a modem communication stabilization method.

It is a system configuration diagram of the present invention. It is an operation | movement description flowchart (whole) of this invention. It is a functional schematic diagram of the VOIP probe of the present invention. It is an operation | movement schematic diagram of the packet quality test | inspection part of this invention. It is a schematic diagram of FAX and modem communication determination of the VOIP probe of the present invention. It is an example of the quality information of this invention. It is an example of a packet of the present invention. It is an example of the exchange of the signal at the time of the modem communication start of this invention. It is size expansion explanatory drawing of the receiving buffer of this invention. It is a modem communication detection schematic diagram by the bit pattern of this invention.

Explanation of symbols

11, 21: VOIP probe 12, 22: SW
13, 23: IP telephone terminal 14, 24: FAX accommodating terminal 31: Network 113: Packet quality inspection unit 41: Terminal (TA) / SW

Claims (5)

A modem communication stabilization system for improving the quality of modem communication of a terminal in a base connected to an IP network,
Connected to the network in the base connected to the IP network, monitoring means for monitoring voice packets destined for transmission / reception of the terminal in the base, and voice of a pattern indicating modem communication as a result of monitoring the packets by the monitoring means A quality information transmitting means for transmitting, when a packet is detected, quality state information including information indicating that the communication is a modem communication to a destination terminal or a switch accommodating the terminal, and a probe,
A reception buffer capable of adjusting the capacity and temporarily storing received packets; and a reception buffer adjusting means for setting a large reception buffer size when receiving quality state information including information indicating modem communication from the probe; A modem communication stabilization system comprising a terminal or a switch having   The probe sets a reception buffer size large in a transmission source terminal or a switch that accommodates the transmission source terminal when it is determined from the monitoring result of the packets transmitted and received by the terminals in the base that the duplex communication is performed. 2. The modem communication stabilization system according to claim 1, wherein quality state information instructing is transmitted.   The probe is connected to a port of a switch connected between the IP network and the network in the base, and whether the packet having the terminal in the base as the transmission destination or the transmission source is a modem communication is further necessary. 3. The modem communication stabilization system according to claim 1, wherein whether or not full-duplex communication is performed is monitored according to.   The terminal or the switch, when the reception buffer size is set to be large, receives a packet while keeping the same size until communication by a voice packet with a transmission source is completed. The modem communication stabilization system according to any one of claims 1 to 3. A modem communication stabilization method for improving the quality of modem communication of a terminal in a base connected to an IP network,
A monitoring step in which a probe connected to a network in a base connected to an IP network monitors a voice packet whose destination is a terminal in the base, and a pattern indicating modem communication as a result of monitoring packets by the monitoring step A quality information transmission step of transmitting quality state information including information indicating that the voice packet is received to a terminal that is a destination or a switch that accommodates the terminal when a voice packet is detected,
A terminal that receives quality state information including information indicating that it is modem communication from the probe or a switch that accommodates the terminal can adjust the capacity, and can set a reception buffer size of a reception buffer that temporarily stores received packets. A modem communication stabilization method comprising a reception buffer adjustment step which is set to be large.

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