JP2000151716A - Gateway - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gateway which can accumulate reception signals from an Internet network by an appropriate amount of buffer and can relax a feeling of incompatibility due to delay. SOLUTION: Every time connected with Internet, the other party, a time and a packet maximum delay time during connection are stored in a storage device. Afterward, statistic processing of stored information is performed and it is stored in the storage device again as prediction data to what extent a packet maximum delay time is generated when connected with the Internet with which party in what time band. Next, when a telephone gateway 401 performs the Internet connection so as to perform an Internet telephone call, the prediction data are collated to and an appropriate packet maximum delay time is decided. When it is recognized that the packet maximum delay time is small, an amount of information to be accumulated in the buffer is reduced; on the contrary, when it is recognized that the packet maximum delay time is large, the amount of information to be accumulated in the buffer is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a gateway for interconnecting networks of different protocols.

[0002]

2. Description of the Related Art Conventionally, it has a function of accommodating a plurality of public telephone lines and connecting to the Internet.
There is provided a gateway having a function of transmitting information transmitted from a public telephone line to the Internet and a function of transmitting information transmitted from the Internet to a public telephone line.

FIG. 4 is a block diagram showing an example of the configuration of a network system using such a gateway. When a telephone call is made between general attendant telephones, the Internet has a communication path via an Internet network. 1 shows a configuration of a telephone system.

[0004] Referring to FIG. 4, a mechanism for making a call between general subscriber telephones will be briefly described.

First, the telephone number of the telephone gateway 108 is dialed from the general subscriber telephone 101 or 102 to the public network 105 and connected to the telephone gateway 108.

Then, the general subscriber telephone 101 or 10
Reference numeral 2 denotes the telephone number of the other party (the general subscriber telephone 103 or 104) with which the telephone call is actually made.
Dial 8.

Upon recognizing the telephone number of the other party (general subscriber telephone 103 or 104), the telephone gateway 108 detects the telephone gateway 109 closest to the general subscriber telephone 103 or 104, and via the Internet 107, the telephone gateway 109. 1
09 and Internet connection.

At this time, the telephone gateway 108
Transmits the telephone number of the other party (general subscriber telephone 103 or 104) to the telephone gateway 109.

Telephone gateway 109 dials public network 106 with the telephone number of the other party (general subscriber telephone 103 or 104).

At this stage, both telephone gateways 108 and 109 enter a communication state between general subscriber telephone 101 or 102 and general subscriber telephone 103 or 104 in response to the incoming call response of the other party (general subscriber telephone 103 or 104). The communication path is configured as follows.

As a result, the general subscriber telephone 10 which is the caller
1 or 102 hears the ring back tone calling the other party (general subscriber telephone 103 or 104) and enters the talking state by the response of the other party (general subscriber telephone 103 or 104).

When making an Internet telephone call as described above, voice signals are transmitted and received via two different communication networks. One is a public telephone line network. The feature is that once a communication path is formed, communication is continuously performed at a constant transmission rate without being affected by network traffic. That is, the call is not interrupted unless a failure occurs during the call.

On the other hand, the Internet network, which is another communication network, is a communication network in which information is packetized and transmitted intermittently, and the transmission rate is easily affected by network traffic and the like. When transmitting information (such as a telephone voice signal) that requires real-time properties over the Internet having such characteristics, a means for correcting fluctuations in packet reception timing is required.

FIG. 5 is an explanatory diagram showing a temporal flow of information (packets) transmitted on the Internet.

[0015] In the figure, reference numeral 201 denotes a packet, and in the case of the configuration shown in Fig. 4, an audio signal is included. Even if the transmission rate per unit time in the Internet network is constant, individual packets are not transmitted at regular intervals as shown in FIG. Some packets are transmitted with an extremely long delay. In this case, the delay time of the packet transmitted with the longest delay is used as the maximum packet delay time in the following description.

The maximum packet delay time is considered to be affected by the traffic volume in the Internet network. When traffic is crowded, many packets traverse the network, and when the transmission capacity of the network is exceeded, the packets may be transmitted extremely late due to the influence. At this time, the maximum packet delay time also increases. On the other hand, when there is no traffic, the number of packets transmitted in the network is small, and the number of elements transmitted with a delay of the packets is reduced. At this time, the maximum packet delay time becomes small.

In the case of an Internet telephone as shown in FIG. 4, the telephone gateway decomposes a packet received from the Internet, performs predetermined signal processing, and transmits an audio signal to a public telephone line.
It is necessary to accumulate data for the maximum packet delay time. If data is not stored in this way, every time a packet is delayed, there is no information to be sent to the public telephone line, resulting in a phenomenon in which the call is interrupted.

Therefore, in the design of the telephone gateway as shown in FIG. 4, it is indispensable to store (buffer) data in consideration of the maximum packet delay time when there is heavy traffic on the Internet.

FIG. 6 is a block diagram showing a configuration example of a conventional telephone gateway. FIG. 6 shows an excerpt of a portion from when the telephone gateway receives a packet from the Internet to when the packet is transmitted as an audio signal to a public telephone line.

In FIG. 6, an Internet interface device 301 performs protocol processing using TCP / IP or the like to establish an Internet connection.

The packet decomposing device 302 extracts an audio signal contained in a packet sent from the Internet interface device 301 and decomposes it into a predetermined digital signal.

The buffer device 303 is composed of a FIFO and accumulates a predetermined digital signal sent from the packet decomposing device 302.

The signal processing device 304 expands an audio signal that is compressed and transmitted on the Internet and converts it into an audio signal that can be transmitted to a public telephone line.

Public telephone line interface device 305
Has a dial function and the like, and controls connection with a public telephone line.

Next, in the configuration of the Internet telephone as shown in FIG. 4, the general subscriber telephones are in a talking state, and the transmission rate on the Internet is constant on average, but is delayed due to traffic or the like. The operation of the telephone gateway when a packet to be transmitted exists will be described with reference to the block diagram of FIG.

First, the telephone gateway receives a packet containing voice information from the Internet by the Internet interface device 301 and sends it to the packet decomposing device 302.

The packet decomposing device 302 transmits a predetermined digital signal to the buffer device 303 in accordance with a packet transmitted from the Internet interface device 301. That is, when a packet is delayed on the Internet and arrives at the telephone gateway, a predetermined digital signal transmitted to the buffer device 303 is also delayed by the delay time.

On the other hand, the signal processing device 304 reads a predetermined digital signal stored in the buffer device 303 at certain intervals. Therefore, if there is a packet delayed on the Internet, the number of predetermined digital signals stored in the buffer device 303 decreases. If the buffer amount of the buffer device 303 is not sufficiently ensured, the buffer becomes empty immediately, and the signal processing device 304 reads empty data.

As a result, in the public telephone line interface device 305, a silent portion is transmitted to the public telephone line, which causes a phenomenon in which voice is interrupted during a call.

In order to prevent the above phenomena, the conventional telephone gateway is provided with a buffer device 303 for buffering information received from the Internet, and there is a packet arriving at some delay during a call. Even so, the call was configured so as not to be interrupted.

This buffer amount is set in consideration of the maximum packet delay time, and is set to such an amount that voice is not interrupted during a call even if the longest packet delay occurs due to traffic fluctuation between telephone gateways or other factors. Has become.

[0032]

As described above, by providing the buffer device 303 for buffering information received from the Internet, an arbitrary packet may arrive with a delay for some reason. The voice will not be interrupted during a call.

However, during a call, a certain amount of voice from the other party is stored and then transmitted to the other party, so that the voice from the other party is heard with a delay. If there is a slight delay, there is no problem in communication, but a delay of several hundred ms or more may occur depending on the setting of the buffer amount.

Such a delay does not exist in a call between ordinary general subscriber telephones, so that there is a risk that the user may feel uncomfortable.

Further, traffic on the Internet fluctuates with time, and even if the same route and the same partner are connected to the Internet, the traffic may be small depending on the time zone.

In this case, since the maximum delay time of the received packet is expected to be small, the buffer amount always assuming the longest packet delay will inevitably delay the arrival of the voice of the other party, and Doesn't make sense. In other words, it is not desirable from the viewpoint of call quality that the voice from the other party is heard late even though there is no fear that the voice will be interrupted.

It is therefore an object of the present invention to provide a gateway which can accumulate a received signal from a line network by a packet switching system with an appropriate buffer amount and can reduce a sense of discomfort due to delay.

[0038]

SUMMARY OF THE INVENTION The present invention has a function of connecting a first circuit network by a circuit switching system and a function of connecting a second circuit network by a packet switching system. And compresses the information received from the second line network and sends it out to the second line network, and decompresses the packetized information received from the second line network to the first line network. In a gateway having a transmitting function, a determining means for determining a fluctuation of a reception timing of a packet received from the second network, and information received from the second network based on a determination result by the determining means. And control means for controlling the accumulation operation.

[0039]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the embodiments of the present invention, the telephone gateway stores the time and the other party (telephone gateway) at that time and the maximum packet delay time during connection every time the Internet connection is made. To memorize. After that, the stored information is statistically processed to estimate how much packet maximum delay time will occur when the Internet connection is made with which party in which time zone. Then, the prediction data is stored in the storage device again.

Next, when the telephone gateway makes an Internet connection in order to actually make an Internet call, the time at that time and the connection partner (telephone gateway) are compared with the stored data of the maximum packet delay time. Thus, an appropriate maximum packet delay time can be recognized.

Then, the amount of the information received from the Internet network to be stored in the buffer is determined according to the recognized maximum packet delay time. When it is recognized that the maximum packet delay time is short, the amount of information stored in the buffer is reduced, and when it is recognized that the maximum packet delay time is long, the amount of information stored in the buffer is increased.

That is, the maximum packet delay time caused by factors such as traffic is predicted depending on the time of making an Internet call and the Internet connection partner, and an appropriate buffer amount is determined each time from the prediction result to make an Internet call. It was done.

FIG. 1 is a block diagram showing a configuration example of a telephone gateway according to an embodiment of the present invention. In the figure, reference numeral 401 denotes the entire telephone gateway,
Arrows indicate the flow of audio information. As shown in FIG. 4, the telephone gateway transmits and receives voice information between a public telephone line network and the Internet network.

Internet interface device 40
Reference numeral 2 performs protocol processing using TCP / IP or the like, and establishes an Internet connection. Further, it has a function of transmitting a packet received from the Internet to the packet decomposing device 403 and a function of transmitting a packet received from the packet assembling device 409 to the Internet.

Public telephone line interface device 408
Has a function of detecting and responding to an incoming call, dialing, etc., and controls connection to a public telephone line. In addition, it has a function of receiving an audio signal from the audio signal decompression processor 406 and transmitting it to the public telephone line, and transmitting an audio signal received from the public telephone line to the audio signal compression processor 407.

The packet decomposing device 403 receives a packet from the Internet interface device 402 and extracts a compressed audio signal included in the packet. The extracted audio signal is transmitted to the buffer device 404 every unit time. At this time, if the timing of receiving a packet from the Internet interface device 402 is delayed, the timing of transmitting an audio signal to the buffer device 404 is also delayed by the delay time.

The buffer device 404 is composed of a FIFO and sequentially accumulates the audio signal sent from the packet decomposing device 403 for each unit time. Thereafter, when a predetermined storage amount is reached, the audio signal is output to the audio signal decompression processing device 406 sequentially from the audio signal previously stored. At this time, the predetermined storage amount stored in the buffer device 404 is controlled by the buffer amount selection device 405, and the stored audio signal can be output at an arbitrary timing.

The buffer amount selection device 405 controls the amount of audio signals stored in the buffer device 404 depending on whether the fluctuation of the reception timing of the packet arriving from the Internet is large or small. When it is highly probable that the received packet is delayed due to factors such as traffic on the Internet, the buffer device 404
When the delay of the received packet is small, the control is performed to reduce the information amount of the stored audio signal.

The audio signal expansion processor 406 expands an audio signal received from the Internet. That is, the audio signal is compressed and transmitted to increase the transmission efficiency on the Internet. Therefore, the received audio signal is subjected to compression processing. The audio signal is subjected to decompression processing, converted into a signal that can be transmitted to the public telephone line network, and transmitted to the public telephone line interface device 408.

The audio signal compression processor 407 is a device for performing compression processing on the audio signal in order to transmit the audio signal compressed on the Internet as described above. It also has the function of performing As a compression method, in March 1996
G. UT approved as a TU-T recommendation 729 (8 kbp
s) and G. 723.1 (6.3 kbps / 5.3 kbp
s) and the like are typical.

The packet assembling device 409 has a function of assembling a compressed audio signal into a packet for transmission on the Internet, and transmitting the audio signal to the Internet interface device in packet units.

When the telephone gateway 401 is in a talking state, the voice received from the public telephone line network is compressed, then packetized and transmitted to the Internet network without buffering. This is because the voice received from the public telephone network is a continuous voice without interruption, and does not need to be buffered.

Conversely, the voice received from the Internet network stores the voice once to the extent that the call is not interrupted due to packets arriving with a delay, and transmits the voice to the public telephone network. At this time, the delay timing (delay time) of the voice packet received from the Internet network is not constant but fluctuates. The timing of this delay is predicted, and an appropriate buffer amount is selected by the buffer amount selection device 405, so that the communication quality is controlled to be the best.

As described above, in the call state, the voice received from the Internet is temporarily stored in the buffer device 40.
4 and then transmitted to the public telephone network. At this time, the audio storage amount is controlled by the buffer amount selection device 405. This control method will be described below with reference to FIG.

FIG. 2 is a block diagram showing in detail the configuration of the peripheral portion of the buffer amount selection device 405. The arrows in the figure indicate the flow of control signals, and indicate the control method between the devices.

The control device 410 is a device that controls each device in the telephone gateway 401. The memory device 411 stores address information of a partner connected to the Internet, time at that time, packet delay information, and the like. The clock device 412 can arbitrarily extract the current time as data.

Internet interface device 40
2. Each of the buffer amount selection device 405, the memory device 411, and the clock device 412 is connected to the control device 410 via a bus, and is controlled by the control device 410.

Under the control of the control device 410, the Internet interface device 402 transmits a test packet or the like including time information to the Internet connection partner at that time and receives a reply from the communication partner to determine the maximum number of packets in a call state. Measure the delay time. In the standby state, a test packet or the like including time information is transmitted to an arbitrary party at an arbitrary time, and a reply from the other party is received to measure the maximum delay time of the packet.

Internet interface device 40
The information of the maximum delay time of the packet obtained by 2 is
All are stored in the memory device 411. The stored information is statistically processed by the control device 410 and stored again in the memory device 411. As a result, it becomes possible to statistically recognize how many packets the maximum delay time will occur when the user connects to the Internet at which time.

Next, during an actual call, the buffer amount selecting device 405 recognizes the current time and the information of the telephone gateway of the connection partner from the clock device 412 and the Internet interface device 402. Then, the maximum delay time of the packet stored in the memory device 411 that matches this information is detected, an appropriate audio buffer amount is determined, and the buffer amount of the buffer device 404 is set.

According to the above-described method, the amount of voice once received from the Internet network is temporarily stored in the buffer device 404. If the probability of the delay of the received packet is low, the buffer amount is reduced and the communication partner is reduced. If the delay of the received packet is high, increase the buffer size so that even if the other party's voice is heard late, the voice will not be interrupted during the call. I do.

FIG. 3 is an explanatory diagram conceptually showing the internal configuration of the memory device 411, and shows how information is stored in the memory device 411 described above.

The information obtained by the Internet interface device 402 and the time at that time are recorded in the memory area 411a. The delay in the figure indicates the maximum delay time of the received packet at that time. In addition, areas such as "Tokyo" and "Osaka" are stored as destinations (connection destinations) connected to the Internet.

On the other hand, the memory area 411b stores information stored in the memory device 411 after statistically processing the information stored in the memory area 411a by the control device 410. This information is represented by a matrix configuration of the other party connected to the Internet (destination area) and the time at that time, and indicates a predicted value of the maximum delay time of the received packet. The buffer amount selection device 405 determines the buffer amount based on the predicted value.

The processing operation described above is executed based on a program stored in advance in a ROM or the like in the control device 410. Instead, a floppy disk, hard disk, CD-ROM, memory A configuration may be employed in which similar programs are stored in various storage media such as a card, and are loaded into the control device 410 as appropriate and executed.

[0066]

As described above, according to the present invention,
For example, when making a call via the Internet network,
In response to fluctuations in the reception timing of the received packet due to factors such as traffic, if the maximum delay time of the received packet is recognized to be small, the amount of information stored in the buffer is reduced and the voice of the other party can be heard late. If the maximum delay time of a received packet is recognized to be large, the amount of information stored in the buffer is increased to solve the problem that the voice is interrupted during a call even if the voice of the other party is heard late. There is an effect that can be done.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration example of a telephone gateway according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a peripheral portion of a telephone gateway buffer amount selection device in the embodiment.

FIG. 3 is an explanatory diagram conceptually showing an internal configuration of a memory device of the telephone gateway in the embodiment.

FIG. 4 is a block diagram illustrating a configuration example of a network system using a gateway.

FIG. 5 is an explanatory diagram showing a temporal flow of information (packets) transmitted on the Internet.

FIG. 6 is a block diagram showing a configuration example of a conventional telephone gateway.

[Explanation of symbols]

 Reference numeral 401: Telephone gateway, 402: Internet interface device, 403: Packet decomposer, 404: Buffer device, 405: Buffer amount selection device, 406: Audio signal decompression processor, 407: Audio signal compression processor, 408: Public telephone line Interface device, 409: Packet assembling device, 410: Control device, 411: Memory device, 412: Clock device.

Continued on front page F term (reference) 5K030 GA14 GA18 HA01 HA08 HB01 HC02 HC13 HD03 HD08 JA05 JT01 KA03 KA06 KA19 LA07 LD18 LE16 MA04 MA13 MB06 MB15 MC08 5K051 AA02 BB01 CC02 EE01 EE02 EE06 GG03 HH27 JJ05 JJ13

Claims (7)

[Claims] 1. A function for connecting a first circuit network based on a circuit switching system and a function for connecting a second circuit network based on a packet switching system, and compressing information received from the first circuit network. A gateway having a function of packetizing and transmitting the packetized information to the second line network, expanding the packetized information received from the second line network, and transmitting the decompressed information to the first line network; Determining means for determining fluctuations in reception timing of a packet received from the second network; and control means for controlling an operation of storing information received from the second network based on a determination result by the determining means. A gateway comprising: 2. The storage device according to claim 1, wherein the storage unit temporarily stores information received from the second network, a storage amount control unit that controls a storage amount of the storage unit, and the second network. During the connection, information storage means for storing the time and / or the connection partner thereof, and fluctuation information of the reception timing of the received packet; statistical processing means for statistically processing the fluctuation information stored in the information storage means; A statistic processing result storage unit for storing a result of the statistic processing; and, when connecting to the second line network, by referring to a time and / or a connection partner at the time and the statistic processing result. Determining means for estimating the degree of fluctuation of the reception timing of the received packet and determining the storage amount of the storage means corresponding to the prediction result. 3. The gateway according to claim 1, wherein the first network is a telephone network, and the second network is an Internet network. 4. It has a function of connecting a first circuit network by a circuit switching method and a function of connecting a second circuit network by a packet switching method, and compresses information received from the first circuit network. Control of a gateway having a function of packetizing and transmitting the packetized information to the second line network, expanding the packetized information received from the second line network, and transmitting the decompressed information to the first line network. In the method, a fluctuation of a reception timing of a packet received from the second network is determined, and based on a result of the determination, the second
A method for controlling a gateway, comprising: controlling a storage operation of information received from a network. 5. The gateway control method according to claim 4, wherein the first network is a telephone network, and the second network is the Internet. 6. A function of connecting a first circuit network based on a circuit switching system and a function of connecting a second circuit network based on a packet switching system, and compressing information received from the first circuit network. Controlling a gateway having a function of packetizing and transmitting the packetized information to the second line network, expanding the packetized information received from the second line network, and transmitting the decompressed information to the first line network. A storage step for temporarily storing information received from the second network, a storage amount control step of controlling a storage amount in the storage step, An information storage step of storing time and / or a connection partner and fluctuation information of a reception timing of a reception packet during connection with the second line network; A statistical processing step of performing statistical processing on the fluctuation information stored by the processing unit; a statistical processing result storing step of storing a result of performing the statistical processing; and a time and a time at that time when a connection with the second network is performed. And / or referring to the connection partner and the statistical processing result to predict the degree of fluctuation of the reception timing of the received packet, and determine a storage amount in the storage step corresponding to the prediction result. A storage medium characterized by storing a program to be executed. 7. The storage medium according to claim 6, wherein the first network is a telephone network, and the second network stores a program that is an Internet network.