JP2001053781A - Communication flow control method, communication terminal, communication flow control management terminal, and program recording medium therefor - Google Patents

Abstract

(57) [Summary] [Problem] To immediately resolve packet congestion. When a terminal (1a) starts a videophone call with a terminal (1b) through a shared line, transmission characteristics information such as a used band and speed are transmitted to terminals (2a, 3) using other shared lines.
(S1), when the terminal 2a starts a videophone call with the terminal 2b, the transmission information from another terminal is referred to to determine the used transmission characteristic information so that congestion does not occur. (S2), when the information is sent to the other terminals 1a, 3a,... (S3), the call / call processing is performed (S5), and 1a is used by the own terminal based on the received transmission characteristic information. The transmission characteristic information is changed (S4), and the terminal 2a starts communication.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication flow control method for a communication method in which a plurality of communication terminals share a band of a relay network and perform packet communication, a communication terminal thereof, and a program recording medium.

[0002]

2. Description of the Related Art An application such as an IP (Internet Protocol) telephone that performs continuous media communication by sharing a trunk line needs to control a communication flow according to a bandwidth currently available to each user. TCP / I
P (Transmission Control Protocol / Internet Protoco
A system for performing communication using continuous media, such as a two-way conference system and a telephone, on a packet transfer network such as l) has a configuration as shown in FIG. 9.

In FIG. 9, a terminal 1 provided at a point a is provided.
Terminals 1b to 3b provided at points a to 3a and point b are main bodies that transmit and receive various data including continuous media information via a packet transfer network. Routers Ra and Rb are devices having a function of relaying and exchanging packets transmitted by terminals, and connect two points a and b via a packet relay network PRN. In the configuration example of FIG. 9, when a certain terminal communicates with a terminal at a different point, communication is performed using a packet relay network PRN that connects the routers Ra and Rb. That is, each terminal performs communication between the points a and b by sharing the line between the routers Ra and Rb.

When performing continuous media communication with such a system configuration, it is necessary to perform some kind of communication flow control according to the sharing status of the shared line. For example, in FIG.
It is assumed that the terminal 2a and the terminal 2b start another TV telephone service while the terminal a and the terminal 1b are executing a high-quality TV telephone service using the maximum bandwidth of the shared line. At this time, if each terminal or network does not perform any communication flow control, the packet of the continuous media communication between the terminals 1a and 1b and the packet of the continuous media communication between the terminals 2a and 2b have a limited band. Since each other's transfer is disturbed on the shared line, the terminal 1a-1b, the terminal 2a-2
During the period “b”, both TV telephone services are interrupted.

[0005] It is also assumed that the same TV telephone service as in the above example is executed between the terminals 1a and 1b. At this time, even if a short-time data communication other than the continuous media communication is attempted between the terminals 3a and 3b, congestion occurs as in the previous example and the communication between both the terminals fails, unless each terminal or the network takes any measures. Occurs. In the conventional method, each terminal determines an available band based on information on a reception situation in which each terminal returns from a communication partner and performs communication flow control.

In the conventional continuous media communication system, in order to cope with the above-described failure, a function of performing communication flow control between terminals is implemented to maintain the quality of service. For example, H. In a TV conference system conforming to H.323 (ITU-T, a standardization recommendation (set of) for multimedia conference communication on a packet communication network), a receiving terminal reports information on packet loss and arrival delay time to a transmitting terminal. In addition, the transmitting terminal implements inter-terminal communication flow control such that the transmission rate and the output buffer control method are changed based on the transmission terminal.

FIG. 10 shows the configuration of a continuous media communication system. The transmitting terminal includes an encoder EC for encoding the input continuous media information and an output buffer OUTB for temporarily storing the encoded data and packetizing the encoded data.
And a transmission / reception I / F 10 for transmitting and receiving packets, and a call control system 11 for controlling communication flow between terminals. The receiving terminal includes an input buffer INB for temporarily storing received data, a decoder DEC for decoding and outputting data, and a transmitting / receiving I / F having the same function as the transmitting terminal.
12 and a call control system 13.

FIG. 11 shows an example of the operation of the conventional inter-terminal communication flow control. Before starting communication by the continuous media communication system, a connection request is sent from the transmission terminal to the reception terminal, and the reception terminal receives the request and determines whether to permit the connection. Is transmitted to the transmitting terminal, and after confirming the connection with the receiving terminal, the transmitting terminal determines the transmission speed and the like. As described above, parameters necessary for communication such as a communication speed and a coding method to be used are first adjusted (call / call processing). This is the encoder EC of the sending terminal,
Output buffer OUTB and input buffer IN of receiving terminal
This is because continuous media information cannot be transmitted unless an encoding method that can be processed by both B and the decoder DE is used for communication.

In the transmitting terminal, after setting the encoder EC and the output buffer OUTB based on the result of the calling / incoming process, transmission of the continuous media information is started. Similarly, the receiving terminal sets the decoder DE and the input buffer INB based on the result of the calling / incoming process, and then starts receiving the continuous media. When a part of the line between the transmitting terminal and the receiving terminal is shared with other communication, the data is transmitted from the transmitting terminal to the receiving terminal in accordance with a situation such as a delay caused by congestion on the shared line or packet discarding. The delay time of the incoming packet fluctuates (packet 3),
A phenomenon that a packet is lost (packet 4) occurs. If such a phenomenon exceeds the permissible limit due to the transmission speed, buffer amount, and the like determined at the time of calling / incoming processing, the receiving terminal cannot obtain continuous media information output.

[0010] Therefore, in the conventional continuous media communication system, inter-terminal communication flow control is realized by the receiving terminal reporting information such as arrival delay and loss status of the packet arriving at the input buffer INB to the transmitting terminal. The receiving terminal uses the input buffer I in the call control system 13.
When the increase of the packet arrival interval is detected from the arrival order and the arrival interval of the packets received by the NB, the input buffer INB
To increase the output delay to the decoder DE to change the accumulated amount of the data, and to attempt to absorb the delay width. It also reports to the transmitting terminal that the delay time has changed. Similarly, when the call control system 13 of the receiving terminal detects a packet loss, it reports to the transmitting terminal that the packet has been lost.

On the other hand, when the call control system 11 detects the report of the occurrence of an abnormality from the receiving terminal, the transmitting terminal converts the transmission packet by a method such as changing the buffer amount of the output buffer OUTB, the packet transmission speed, and the output speed of the encoder EC. The transmission speed is adjusted to ensure that the data arrives at the receiving terminal.
As described above, the communication flow control in the conventional continuous media communication system is characterized in that it is performed based on information fed back from the receiving terminal to the transmitting terminal.

[0012] In an actual continuous media communication system, a method of controlling the input buffer / output buffer amount and changing the transmission rate according to the characteristics of the media handled by each system and the encoding system is adopted. Also, various parameters are employed for a trigger for the call control system to perform communication flow control depending on the system.

[0013]

Since each terminal performs communication flow control independently, it takes time to follow a change in the communication trend of another terminal, and the service is not stable until the terminal transits to a stable state. If you want to (explicitly) change the way of using a line on a terminal sharing a line, for example, if you want to limit the maximum bandwidth, you have to take measures such as changing the settings for each terminal. Was busy.

By the way, in the conventional continuous media communication system based on the communication flow control between terminals as shown in FIG. 11, after the congestion actually occurs, the congestion is suppressed by the communication flow control and the state is again stabilized. By then, the communication flow control of the congestion detection at the receiving terminal, its report, and control based on the report at the transmitting terminal must be executed at least once between each transmitting and receiving terminal. Also, the receiving terminal starts the feedback not at the moment when congestion occurs and a failure occurs in any of the call packets, but at the moment when the terminal detects that a failure has occurred in the relevant call packet. is there. For this reason, there is a problem that it takes a long time from when the congestion actually occurs until all the transmitting and receiving terminals deal with the congestion and the service recovers normally (problem 1).

As means for avoiding this problem in the conventional system, the maximum transmission rate that can be used by each continuous media communication terminal is determined according to the maximum bandwidth of a shared line that becomes a bottleneck and the number of terminals that use the line. A method of setting this in each communication terminal is known. This is because, when a group of communication terminals managed under the same management policy shares a line that becomes a bottleneck, for example, a group of communication terminals under the same management connected to a LAN are connected to a WAN through a shared access line. This is a particularly effective method when it is connected to a (wide area network).

Also, when the maximum capacity of the continuous media communication occupying the shared line is desired to be suppressed to the maximum bandwidth or less, for example, because the shared line serving as a bottleneck is used for other than the continuous media communication. This method can be used. However, this method has a problem that even when there is a sufficient band available due to a small number of communication terminals and the like, the communication terminals cannot perform their original performance due to transmission rate limitation. In addition, there is a problem that the settings of a plurality of terminals must be changed and managed (problem 2).

When a two-way call such as a telephone call is performed, it is desirable that the user on the transmitting side assumes the quality of continuous media information transmitted to the receiving party in order to facilitate a smooth conversation. . However, in the conventional apparatus, if the change in the quality of the received information caused by the occurrence of congestion and the communication flow control accompanying it is notified in advance, it does not seem strange, but in the past, the deterioration in the quality of the received information has been There was a problem that it was not possible to make an immediate judgment from a result other than the obtained continuous media reproduction output, which hindered conversation (problem 3).

[0018]

In order to solve the problem, transmission characteristic information such as communication band and transmission speed used between terminals sharing a line is shared, and the established transmission characteristic information is used. Each terminal reflects on the communication flow control. That is, the line use information is mutually exchanged between transmitting terminals sharing the line, and this is used for transmission rate control together with feedback information from the receiving terminal.

With this configuration, it is possible to quickly respond to a change in state, and the stability is increased. On the premise of the solution to the problem 1, on the premise of the solution to the problem 1, a device (management terminal) for managing the number / use transmission characteristic information between the terminals sharing a line is installed, and a communication flow control request to the terminal is issued. Let me tell you. The terminals reflect the instruction from the management terminal in their own communication flow control.

The communication flow control of each terminal can be designated collectively by setting the management terminal. Before switching the codec for Problem 3, explicitly notify the sending user that the switch has occurred.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Solution to Problem 1 In a first communication flow control method according to the present invention, when a call is established / terminated in a continuous media communication, the transmission terminal transmits / receives a communication band or the like of a packet whose transmission / reception starts / terminates. The characteristic information is notified to other transmitting terminals sharing the line.

For example, when the terminals 1a-3a sharing the access line in FIG. 9 exchange the use transmission characteristic information, the first communication flow control method is performed as follows. In FIG. 9, it is assumed that the terminal 2a and the terminal 2b start another TV telephone service while the terminal 1a is executing the TV telephone service with the terminal 1b as in the previous example. FIG. 1 shows the operation of the first communication flow control according to the present invention at this time.

First, when the terminal 1a starts the TV telephone service, the information of the communication performed by itself is transmitted to the other terminals 2a and 3a which may share the line (S1). Subsequently, when the terminal 2a starts the TV telephone service, the terminal 2a determines its own transmission characteristic information, that is, the communication means with reference to the communication status of the terminal 1a previously notified, that is, the transmission characteristic information (S2). The transmission characteristic information and the communication start information are returned to the other terminals 1a and 3a (S3). Upon receiving these pieces of information, the terminal 1a starts communication flow control of its own terminal based on the information (S5). After the notification, the terminal 2a performs a calling / calling process (S4) and starts communication (S6).

As shown in FIG. 1, in the method of the present invention, the terminal 1a does not wait for feedback information based on the start of communication of the terminal 2a from the terminal 1b, but based on the transmission characteristic information of the communication terminal 2a at the start of communication. Since communication flow control can be started, service recovery faster than the conventional method can be realized. In particular, after transmitting the transmission characteristic information to the terminal 1a,
If communication flow control is performed based on the transmission characteristic information received by the terminal 1a before the terminal 2a starts communication, congestion does not occur.

When a receiving terminal performs a connection process (call / incoming process) in response to a connection request from a transmitting terminal, a line use status (transmission characteristic information) notified from another terminal sharing the line. The communication flow control is performed by determining transmission characteristic information such as a communication band that can be used by itself based on the communication flow. That is, as shown in FIG. 11, prior to starting communication by the continuous media communication system, parameters necessary for communication such as a communication speed to be used and an encoding method are adjusted (calling / calling processing). At this time, a parameter that the receiving terminal replies to the transmitting terminal is restricted according to the current line usage status (transmission characteristic information).

Solution to Problem 2 The second communication flow control method according to the present invention is based on the solution to the problem 1 described above. For example, as shown in FIG. Point a, b
In each of the communication networks, the management terminals 21a and 21b are provided, respectively, and when each of the terminals 1a to 3a and 1b to 3b establishes / ends the call of the continuous media communication, the transmission characteristic information such as the communication band of the packet to start / end its own transmission. The corresponding management terminal 21
a, 21b, respectively, and each management terminal 21a, 2
1b collects information notified from each terminal, determines transmission characteristic information as a guideline of communication flow control, and notifies the terminals 1a, 2a, 1b, and 2b of this.

In the conventional communication flow control, each terminal individually determines the communication flow control parameter by estimating the congestion status of the shared communication path based on the feedback information. There was a possibility. However, in the method of the present invention, the communication flow control parameters (transmission characteristic information) of each terminal are collectively determined by the management terminal, so that communication flow control errors can be reduced.

When the maximum capacity of the continuous media communication occupying the shared line is desired to be suppressed to the maximum bandwidth or less because the bottleneck of the shared line is used for other than the continuous media communication, etc. In determining the control guideline in the second communication flow control method of the present invention, these information may be added. Solution to Problem 3 As with the communication flow control method of the conventional device, in the communication flow control method of the present invention, the quality of continuous media information may change with transmission speed adjustment. Therefore, in the continuous media communication terminal according to the present invention, the change in the quality of the continuous media information transmitted at the same time as adjusting the transmission speed is explicitly shown to the user as a switching signal, that is, displayed on the interface device or sound. Notify and inform.

Embodiments Embodiments of the present invention will be described below. FIG. 2 shows a continuous media communication system to which the present invention is applied. Terminal 1a-
3a and terminals 1b-3b are terminals capable of transmitting and receiving audio and images as continuous media. Each point a,
The terminals 1a-3a and 1b-3b installed at the location b are interconnected via Ethernet (Ethernet) at each point.

The management terminals 21a and 21b are devices for performing control for determining and instructing a guideline of communication flow control of each terminal in the second communication flow control method of the present invention, and, similarly to other terminals, Ethernet (100 Mbit). / S), the other terminals 1a-3a, 1b-3 for each point a, b
b. In this embodiment, in FIG. 2, a terminal and a management terminal connected to each point a and b by Ethernet are IP (Internet) as a communication protocol.
Protocol).

The terminal / management terminal at each point is composed of the terminal / management terminal at another point, the routers Ra and Rb, and the IP relay network PRN.
Can communicate with each other. In this embodiment, the capacity of each shared line between the routers Ra and Rb at each point and the IP relay network PRN is set to T1 (1.5 Mbit / s).
In addition, it is set that a sufficient band that does not cause congestion is secured in the IP relay network PRN. In this embodiment, it is set that line use information, that is, use transmission characteristic information is shared by each of the points a and b. That is, the terminals 1a and 2 in FIG.
a, 3a and terminals 1b, 2b, 3b are shared groups of respective points. A management terminal 2 that gives a communication flow control guideline (transmission characteristic information) to a group of each point a and b.
1a and 21b belong respectively.

The terminal (terminal 1a-
3a, 1b-3b) shows the functional configuration of FIG. A terminal is a device that is a main body of data transmission / reception having a function of a transmission terminal / reception terminal in a continuous media communication system. The audio / video CODEC (codec) 25 encodes an externally input audio / video signal in accordance with an encoding method specified by the call state control unit 26 and passes the encoded audio / image signal to the data processing unit 27. Also, the audio / video data passed from the data processing unit 27 is decoded according to the encoding method specified by the call state control unit 26 and output to the outside.

The data processing unit 27 converts a received packet containing data of voice / image information and call control information into a network.
(Network) Each processing unit 2 received from the I / F 28
It has a function to distribute processing to 7a to 27c. The data transmitted from each of the processing units 27a to 27c is
It has a function of passing it to the ork I / F 28 and transmitting it to the outside. In this embodiment, the processing blocks of the data processing unit 27 are classified into the following three types. Code reception processing unit 27a The audio / video data arriving at the terminal is
Deliver to 25. Code transmission processing unit 27b transmits the audio / image data received from audio / video CODEC 25 to the other party. Control data processing unit 27c Distributes information on call control arriving from another terminal / management terminal to call state control unit 26. Also, the call state control unit 2
6 sends a control signal to another terminal / management terminal via Network
The data is transferred to the I / F 28 and transmitted.

The network I / F 28 is a network to which terminals are connected (Ethernet in this embodiment).
The data input / output processing between t) and the data processing unit 27 is performed. The call state control unit 26 controls the call connection with the call destination and the audio / video CODEC 25 based on the request from the user received from the user input / output device 29 and the control signal received from the control data processing unit 27c.

The group management table 31 is a table for managing / storing each terminal of the group to which the terminal belongs, the management terminal, and the state of each call, that is, transmission characteristic information used by the terminal. The information in the group management table 31 is used as information for controlling the call state (transmission characteristic information). The user control interface 32 performs a user's operation on the terminal and a process of presenting the current status of the terminal to the user.

The user input / output device 29 is an input / output device such as an operation panel and a display for directly instructing a user to make a call, receive a call, or disconnect a call. FIG. 4 shows the configuration of the management terminal 21a (21b) in FIG. The management terminal is
This configuration is such that a function for managing the communication terminals of the entire group by extending the control of the call processing is added, except for the functions related to the media processing from the communication terminals that transmit / receive the media.

The functions of the components of the management terminal having functions different from those of a normal terminal will be described below. The functions of the other components have the same functions as those of the terminal having the same name. Based on the request from the user received from the user control I / F 32 and the control signal received from the control data processing unit 27c, the call state control unit 33 provides a guideline regarding call connection with a communication destination for each communication terminal belonging to the group, That is, it indicates the transmission characteristic information to be used.

The user input / output device 29 is composed of a device such as an operation panel and a display for the user to directly confirm and operate the call status. Gist of Operation (that is, Protocol) Here, an embodiment will be described focusing on the group notification system related to the present invention (the description of the call control protocol and the like is expressed more simply than it actually is).

FIGS. 5 to 7 show the processing flow of each apparatus when the present invention is applied to the system of FIG. FIG. 5 is a processing flow of a terminal that performs continuous media transmission, that is, a transmitting terminal. FIG. 6 is a processing flow of a terminal that performs continuous media reception, that is, a receiving terminal. FIG. 7 is a processing flow of the management terminal. Hereinafter, the operation of each device in this embodiment will be described with reference to these flowcharts. (1) Activation of Terminal and Management Terminal and Connection to Network According to the present invention, information (transmission characteristic information) and control information on a communication flow from a certain terminal / management terminal to all terminals / management terminals sharing a line. Is required, that is, a broadcast function. In this embodiment, since IP is used for communication between terminals, an IP multicast function (IP-Multicast) is used as a broadcast function.

Therefore, when each terminal is activated, it first performs a process of joining a predetermined multicast group (8a-8b), (9a-9b), and enters a standby state (8c, 9b). Similarly, when the management terminal starts up, it first performs a process of joining the multicast group (10a to 10b), and then enters a state of waiting for control information reception (10c). (2) Processing of the transmitting terminal during transmission standby While the transmitting terminal is waiting for a call (8c), information notification of communication start / end (including the transmission characteristic information used in the start information) is detected from another terminal. (8q), the group management table 31 is updated based on the notification (8q).
r). (3) From Outgoing Call to Incoming Call and Establishment When the call state control unit 26 of the transmitting terminal accepts the calling request via the user control I / F 32, it transmits a connection request to the destination receiving terminal (8d), Wait for an answer (8e).

The receiving terminal receives the connection request and prompts the user to determine whether to permit the incoming call, using the user input / output device 29. Finally, when the connection is rejected, the transmission terminal is replied to the effect that the connection is rejected (9d). Conversely, when the incoming call is permitted, the transmitting terminal is replied to the transmitting terminal that the connection is permitted together with the information of the available encoding method (9e). For the encoding method to be answered here,
At step C25, the receiving terminal selects a coding method that does not cause congestion from the coding methods that can be used at the present time and that responds to the communication band currently available. The currently available communication band is determined from the communication status (transmission characteristic information) of the other terminals registered in the group management table 31.

When the transmitting terminal is refused connection by the receiving terminal which has issued the connection request, the user input / output device 29 notifies the user of this fact and returns to the standby state (8c). (4) From Selection of Coding Method to Start of Communication Upon receiving the connection approval from the receiving terminal, the transmitting terminal receives the connection approval and receives the coding information (transmission characteristic information) usable by the receiving terminal and the group management table 31. Determines the coding system (transmission characteristic information) to be used for transmission based on information (transmission characteristic information) on the open bandwidth of the shared line that can be determined from the communication status (transmission characteristic information) of the other transmitting terminal recorded in the (8f) to start transmission (8h).

At this time, each terminal and the management terminal are notified of the fact that they themselves start transmitting and the information on the coding system used at that time and the band consumed thereby, that is, transmission characteristic information (8g). . (5) Communication flow control during communication The receiving terminal receiving the continuous media information receives the packet arriving at the data processing unit 27 and outputs the audio image CO
While the DEC 25 performs the reproduction process (9h), the call state control unit 26 monitors the packet arrival status.
When the call state control unit 26 determines that the network is congested from the packet delay or loss, the receiving terminal informs the transmitting terminal that a problem has occurred (9i, 9j).

On the other hand, in the transmitting terminal, the audio image CODEC2
While performing the process of transmitting the continuous media information encoded in 5 (8h), the call state control unit 26 monitors whether or not the communication flow control information is transmitted. When the transmitting terminal receives a busy notification (transmission characteristic information) or an end notification (transmission characteristic information) from another terminal, the transmitting terminal first updates information in the group management table 31 (8o).

Next, the own transmission rate (transmission characteristic information) is reexamined (8p).
The ODEC 25 is switched. Sound image CODEC2
5 is switched to the CODEC through the user input / output device 29 with the telop character and the changed sound.
Is changed (8s), and if necessary, call setting information (transmission characteristic information) changed by itself.
Is again notified to each terminal and the management terminal (8t).

When the transmitting terminal receives a request for changing the transmission rate (transmission characteristic information) from the management terminal (8k), the transmission rate (transmission characteristic information) is reexamined, the CODEC 25 is switched, and the buffer in the data processing unit 27 is changed. Change the control method. At this time, if necessary, each terminal and the management terminal are again notified of the call setting information (transmission characteristic information) changed by themselves (8t). When the audio / video CODEC is switched, the sender is notified through the user input / output device 29 by a telop character and a change sound to the sender that the CODEC has been changed (8s). (6) Termination of Communication When the user instructs termination of communication through the user input / output device 29, each terminal starts termination processing (8l).
-8n, 9f-9g). At this time, the transmitting terminal notifies each communication / management terminal that its own transmission has been completed and the area of the shared line has been released (8 m). (7) Operation of Management Terminal When the initialization at the time of startup is completed, the management terminal checks whether or not there is a notification of transmission characteristic information from another terminal.
It waits while monitoring in 3 (10c). When a notification of communication start / end / band change (transmission characteristic information) is detected from another terminal, the management terminal first enters the group management table 3
1 is performed (10e).

Next, it is determined whether or not communication flow control is necessary based on the band use status of each communication with respect to the capacity of the shared line, the communication flow control policy instructed from the user input / output device 29 (10f). A recommended transmission rate (transmission characteristic information) is calculated and reported to each communication terminal (10g). For example, a communication flow control policy is set by the management terminal for the line (T1: 1.5 Mbps) shared in this embodiment (FIG. 2) to equally allocate the line band to each continuous media communication. Assume that At this time, it is assumed that the communication start information of 1 Mbps is newly detected in a state where only one communication start information of 1 Mbps is registered in the group management table 31. In this case, the management terminal determines a rate of 750 Kbps per communication as the recommended rate (10f), and notifies this to each terminal (10g). Upon receiving this request (8k), the transmitting terminal reviews and changes the transmission rate (8p).

As another example, a case where the function of the management terminal is linked with the packet transfer function of the router will be particularly described. In a continuous media communication system as shown in FIG. 2, all data passing through a shared line are transmitted through routers Ra and R.
b. With such a router, it is possible to know the line use status of the entire data communication including communication other than continuous media communication. Therefore, if the information on the line usage status detected by the router is used as a trigger for the flow control judgment by the management terminal, it is possible to determine the transmission rate more accurately.

For example, the management terminal sets a communication flow control policy for equally allocating a line band to each communication line (T1: 1.5 Mbps) shared in this embodiment (FIG. 2). Suppose that At this time 1M
It is assumed that in a state where only one bps communication start information is registered in the group management table 31, another terminal starts data transfer in the router and congestion is detected in the router Ra. In this case, the recommended rate is recalculated using the congestion information detected by the router Ra as a trigger (10
f) By transmitting this to each terminal (10g), communication flow control policy sharing between communication other than continuous media communication and continuous media communication can be realized.

In the above description, the communication information transmitted and received by each communication terminal is not limited to continuous media information, but may be, for example, data. Further, the method of the present invention can be implemented by decoding and executing a program by a computer.

[0051]

As described above, according to the present invention, each communication terminal sharing a communication path shares its used transmission characteristic information, and when starting a new communication, the other shared terminals have the same shared transmission characteristic information. With reference to the used transmission characteristic information of the communication terminal, to set the used transmission characteristic information so that the shared communication path is not congested,
Alternatively, the management terminal collects the used transmission characteristic information from each communication terminal and, when congestion is expected in the shared communication path, changes the transmission characteristic information of at least one communication terminal so that congestion does not occur. , It is possible to shorten the recovery time until a service interruption caused by the occurrence of congestion in the shared communication path returns to a normal state by communication flow control while a plurality of terminals are performing communication.

In the past, since all terminals sharing a communication path independently changed the setting of the transmission characteristic information, it took time for the state of the communication terminals of different communication partners to become appropriate. However, the maximum capacity of continuous media communication occupying the shared communication path can be reduced to less than the target bandwidth only by changing the parameter (transmission characteristic information) of the guideline determination of the management terminal that determines the guideline of the communication flow control of the present invention. Can be suppressed.

For example, in FIG. 9, as in the previous example, while the terminal 1a is executing the TV phone service with the terminal 1b, the terminal 2a
It is assumed that the terminal 2b starts another TV phone service. FIG. 8A shows a transition of the communication bandwidth by the conventional communication flow control at this time, and FIG. 8B shows a transition of the communication bandwidth by the communication flow control according to the present invention. In FIG. 8A of the conventional method, a period in which the feedback control is tried a plurality of times between the terminals from the point of occurrence of congestion until the state converges to a stable state again (points t2 to t3 in FIG. 8A).
is necessary. During this transition period, each communication service is temporarily interrupted by the effects of unexpected packet delays and losses caused by congestion.

On the other hand, when the communication flow control of the present invention is applied (FIG. 8B), at the time when the terminal 2a and the terminal 2b newly start communication, each terminal can use the band currently available to itself based on the communication status of the other communication terminal. Since the width (communication characteristic information) can be determined immediately, service interruption due to the occurrence of congestion can be avoided. In the conventional method, if the transmission / reception performance of the terminal is larger than the available line capacity, transmission exceeding the allowable line speed immediately after the start of communication results in congestion and service interruption. was there.

On the other hand, according to the third communication flow control method of the present invention, the reception speed is limited at the time of calling / incoming processing by reflecting the communication status of the other terminal. No extra transmissions occur. The quality of the continuous media information received by the receiver may change due to the adjustment of the transmission speed according to the communication flow control method as described above.
Conventionally, since the sender continues communication without knowing that the reproduction quality on the receiver side has changed, there has been an obstacle particularly in communication in two-way communication. However, in the present invention,
Adjustment of the transmission speed is explicitly indicated to the sender as a switching signal, so that it is possible to prevent a trouble occurring in communication.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a first communication flow control method of the present invention.

FIG. 2 is a diagram showing an example of a communication system to which a second communication flow control method according to the present invention is applied.

FIG. 3 is a block diagram showing an example of a functional configuration of a communication terminal according to an embodiment of the present invention.

FIG. 4 is a block diagram showing a functional configuration example of an embodiment of the communication flow control management terminal of the present invention.

FIG. 5 is a flowchart showing a procedure of a transmission process of a communication terminal in the system of FIG. 2;

FIG. 6 is a flowchart showing a procedure of a reception process of the communication terminal in the system of FIG. 2;

FIG. 7 is a flowchart showing a processing procedure of a management terminal in the system of FIG. 2;

FIG. 8 shows the transition of the communication bandwidth by the communication flow control, where A is the case according to the conventional method and B is the case according to the first method of the present invention.

FIG. 9 is a diagram showing a configuration example of a continuous media communication system.

FIG. 10 is a diagram showing a configuration example of a transmitting terminal and a receiving terminal of the continuous media communication system.

FIG. 11 is a diagram showing a procedure of conventional communication flow control between terminals.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Keiji Shimizu 2-3-1, Otemachi, Chiyoda-ku, Tokyo F-term within Nippon Telegraph and Telephone Corporation (reference) 5K030 HA08 HD03 JT02 LC01 LC09 5K033 CA08 CC01 DA05 DB18 5K067 AA28 BB21 CC08 EE02 EE16 FF02 GG01 9A001 BB04 CC07 DD10 EE04 JJ24

Claims (14)

[Claims] After encoding and packetizing communication information,
A communication flow control method of a communication method of transmitting to a destination communication terminal via a communication path sharing a transmission band with another communication terminal, the communication path being executed between continuous media communication terminals sharing the communication path. Communication characteristics such as communication bandwidth and transmission speed of each other, determine available transmission characteristics information using the shared information at the start of communication, and execute communication using the determined transmission characteristics information. Characteristic communication flow control method. 2. When another communication terminal starts the communication,
2. The communication flow control method according to claim 1, wherein upon receiving the used transmission characteristic information, the communication flow being executed by the own communication terminal is changed based on the received information so that congestion does not occur. 3. The communication flow control method according to claim 1, wherein the determination of the available transmission characteristic information is performed by a transmitting communication terminal that starts the communication. 4. The communication flow control method according to claim 1, wherein the determination of the available transmission characteristic information is performed by a receiving communication terminal that is starting the communication. 5. When a call for communication information is established, transmission characteristic information used by the transmitting communication terminal is notified to another communication terminal sharing the communication path, and the transmission characteristic information being executed is shared with each other. The communication flow control method according to any one of claims 1 to 4, wherein notification of the termination of the call is made to each of the other communication terminals. 6. A communication flow control management terminal, wherein said communication flow control management terminal notifies said communication flow control management terminal of transmission characteristic information of each communication terminal sharing said communication path. 6. A system according to claim 1, wherein information is comprehensively managed, and when a congestion state of said shared communication path is expected, at least one communication terminal is instructed of a communication flow in which said congestion does not occur. The communication flow control method according to any one of the above. 7. The communication information is encoded by a codec, packetized by a data processing unit, and transmitted to a destination communication terminal via a communication path sharing a transmission band with another communication terminal.
A communication terminal that temporarily stores a packet received via the shared communication path in the data processing unit, decodes the codec with the codec, and outputs communication information. Control data processing means for supplying transmission characteristic information such as transmission speed to the call state control unit, and transmitting the use transmission characteristic information of the own communication terminal from the call state control unit to another terminal; A group management table for managing / storing transmission characteristic information received from each of the other communication terminals belonging to the group; a request from the user received from the user input / output device;
Based on the contents of the group management table, controls the settings for the codec, and based on the transmission characteristics information received from the control data processing means, the call state control means for controlling the settings for the codec; A communication terminal comprising: the user input / output device for performing operations such as incoming call and call disconnection. 8. A connection between each communication terminal in a communication system in which communication information is encoded and packetized by a communication terminal and transmitted to a destination communication terminal via a communication path sharing a transmission band with another communication terminal. A communication flow control management terminal that receives a notification of transmission characteristic information such as use, communication band, and transmission speed from the communication terminal, updates the corresponding content of the group management table, and transmits the transmission characteristic in the group management table. Call state control means for examining the use status of the shared communication path from the information, determining transmission characteristic information of each communication terminal so as not to cause congestion, and notifying the communication terminal of the transmission characteristic information; A communication flow control management terminal comprising: a group management table for storing transmission characteristic information notified from each communication terminal by means. 9. Encoding and packetizing communication information,
A recording medium that stores a program executed by a computer of a communication terminal that transmits a communication band to another communication terminal via a communication path that shares a transmission band with another communication terminal. A process of receiving transmission characteristic information such as a speed; a process of storing the received transmission characteristic information in a group management table; and a transmission request, when a call request is input, the transmission characteristic information of the communication terminal in addition to the group management table. With reference to the above, a process of determining transmission characteristic information that can be used by the own terminal and setting a communication speed, an encoding scheme, and the like, and a process of notifying the set transmission characteristic information to another communication terminal, A recording medium recording a program to be executed by the computer. 10. Upon receiving transmission characteristic information from another communication terminal, changing the transmission characteristic information of the own communication terminal so as not to cause congestion in the communication path, and transmitting the changed transmission characteristic information to another communication terminal. The recording medium according to claim 9, wherein the program includes a program for causing the computer to execute a process of notifying a terminal. 11. A program for causing the computer to execute a process of receiving transmission characteristic information from a communication flow control management terminal, and a process of changing and setting transmission characteristic information of its own communication terminal in accordance with the received transmission characteristic information. The recording medium according to claim 9, wherein the program includes: 12. A process of receiving a connection request from a transmitting terminal, and, when permitting the connection request, referring to transmission characteristic information of another communication terminal other than the group management table, to transmit data that can be used by the own communication terminal. The program includes a program for causing the computer to execute a process of judging characteristic information and selecting an available encoding system, and a process of transmitting the selected encoding system and connection permission to the communication terminal. The recording medium according to any one of claims 9 to 11, wherein: 13. The program according to claim 9, wherein when the change setting is performed, the program includes a program for causing the computer to execute a process of notifying the user input / output device of the change setting. The recording medium according to the above. 14. The program according to claim 11, wherein the program includes a program for causing the computer to execute a process of transmitting used transmission characteristic information to the communication flow control management terminal at the start of communication. Recording medium.