JP2000224230A - Real time communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a communication method by which quality of information data can be enhanced at reproducing information data with tight real time performance such as video and audio data in the case that a physical network with a band non-warrant type is interposed between a transmission terminal and a reception terminal. SOLUTION: Information data are transmitted by using a plurality of communication channels in common. Or the information data are transmitted with a very small time difference among a plurality of communication channels. Or information data are transmitted by interposing different queues from each of a plurality of the communication channels. Or different information data are transmitted for each of a plurality of communication channels depending on the importance. In the communication methods above, when the information data transmitted through a plurality of the communication channels reach a reception terminal 11, the information data are assembled by synchronizing a plurality of the communication channels. Or the information data not arrived up to a prescribed time and the information data arrived in overlapping may be aborted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for communicating information data, such as video and audio, which is strictly required in real time, using a communication path whose bandwidth is not guaranteed, and particularly to improving the quality of such communication. For new communication methods for:

[0002]

2. Description of the Related Art Conventionally, when information data having strict real-time characteristics is transmitted / received, a band-guaranteed communication channel has been used. However, due to advances in audio and video applications, the number of cases in which such information data is transmitted and received on a non-guaranteed communication channel, such as the Internet or an in-house LAN, which is less expensive than a guaranteed bandwidth type, is increasing dramatically. When information data is transmitted using such a non-guaranteed communication channel, the integrity of the information data is ensured by retransmission using a higher-level communication protocol such as TCP.
Since the lack of the information data is detected using the protocol timer or the acknowledgment in the order of seconds and the information data is retransmitted, it takes a long time to receive the missing information data. As a result, a phenomenon that the video is stopped or a phenomenon that the sound is interrupted occurs. In addition, when using a higher-level protocol such as UDP that does not perform retransmission, when information data that is strict in real time is lost, error correction within a range possible by an application program may be performed. The functions are not originally required for each application, and they do not solve the problem sufficiently, such as requiring redundant data and calculation time for correction.

[0003]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide a method for transmitting video, audio, etc., when a non-guaranteed physical network is interposed between a transmitting terminal and a receiving terminal. It is an object of the present invention to provide a communication method capable of improving the quality of information data which is strict in real time at the time of reproduction.

[0004]

In order to achieve the above object, a real-time communication method according to the present invention provides information to a receiving terminal via at least one non-guaranteed physical network. When transmitting data, information data is transmitted using a plurality of communication paths. Also, information data is transmitted with a slight time difference between a plurality of communication paths. Also,
A different queue is provided for each of a plurality of communication paths to transmit information data. Also, different information data is transmitted for each of the plurality of communication paths according to the importance.

In these real-time communication methods according to the present invention, when information data transmitted by a plurality of communication paths arrive at a receiving terminal, the information data is assembled by synchronizing the plurality of communication paths. You may. Further, information data that does not arrive by a predetermined time and information data that has arrived redundantly may be discarded.

According to the method of the present invention, in addition to the non-guaranteed connection which is logically set between the data transmission source and the data reception destination on the physical communication path, one or more transmissions are provided. Data is also sent in parallel on the secondary connection,
The receiving side assembles and uses data that has arrived at all connections by a predetermined reproduction time. These connections are provided as a single connection integrating a plurality of connections to the application program.

[0007]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a network diagram for explaining an embodiment of the present invention. A transmitting terminal 10 and a receiving terminal 11 are connected to a network without or via a relay device. FIG. 2 is a diagram showing the correspondence between a transmitted packet and a successfully received packet.

[First Embodiment] FIG. 1A shows a first embodiment of the present invention.
It is a diagram illustrating an embodiment, a transmitting terminal 10 and a receiving terminal 11 are connected to the same network without the intervention of a relay device, and the information packet 100, using the main connection 12 from the transmitting terminal 10 to the receiving terminal 11. Information packets 110, 111, and 112 are transmitted using the sub-connection 13. In this embodiment, the transmission terminal 10 transmits the same information data between the main connection 12 and the sub-connection 13 with a small time difference. Information packets 100 and 110
, X and 101 and 111 have Y, and 102 and 112 have Z.

FIG. 2A shows transmitted packets and received packets in the first embodiment. in this case,
Although the information packet 101 is lost on the way, since the information data 111 having the same content is received, the receiving terminal 11 can obtain all the data of X, Y and Z. As described above, by transmitting the same data even in the sub-connection with a slight time difference from the main connection, the probability of losing information data due to collision in a LAN such as Ethernet can be reduced.

FIG. 3 is a diagram showing an example of the configuration of the transmitting terminal 10 and the receiving terminal 11. The transmission terminal 10 includes a transmission application 21 such as a video server,
2, a sub-connection transmission adjustment unit 23 is included. On the other hand, the receiving terminal 11 includes a main connection data receiving unit 24, a sub connection data receiving unit 25, a data assembling unit 26, and a receiving application 27 such as a video reproducing application. When the information data arrives at the data transmission unit 22 from the transmission application 21, the data transmission unit 22 transmits the information data to the main connection 12, and transmits the information data to one or a plurality of sub-connection transmission adjustment units 23. The sub-connection transmission adjustment unit 23 transmits the data to the sub-connection 13 with a delay before transmission. The transmitted information data is received by the main connection data receiving unit 24 and the sub connection data receiving unit 25, respectively, and the data assembling unit 26
Sent to The data assembling section 26 passes the information data to the receiving application 27 after assembling the information data.

FIG. 4 shows a format of an information data packet transmitted to the main connection 12 and the sub connection 13.
31 is a diagram illustrating an example of 31. FIG. An information packet is transmitted between a protocol header section 32 (for example, a UDP protocol header) and an information data section 34 in a format in which a transmission time information section 33 used by the data assembling section 26 on the receiving side is added.

FIG. 5 is a flowchart showing the processing in the data transmission section 22 of FIG. When the data transmission unit 22 receives the transmission data (S01), it adds transmission information information (S02), and first transmits information data to the main connection 12 (S03). Next, it is determined whether or not the information data is to be transmitted to the sub-connection (S04). In this embodiment, all the information data is transmitted to the sub-connection transmission adjusting unit 23 (S0).
Five).

FIG. 6 shows a sub-connection transmission adjusting unit of FIG.
24 is a flowchart showing a process in 23. When the sub-connection transmission adjusting unit 23 receives the transmission data from the data transmission unit 22 (S11), it performs a data transmission delay process (S1).
2), and send it to the sub-connection 13 after processing (S13).

As shown in the reception time chart of the receiving terminal in FIG. 7, the data received by the receiving terminal 11 is classified into three types: information data that has already been received, information data that is being received, and information data that has not been received. Is done. In FIG. 7, Ta is the transmission time information of the information data whose reception has been completed, Tb is the maximum value of the transmission time information of the information data being received, Δ is the allowable delay time given in advance, and the transmission time of the received information data. Let T be information.

FIG. 8 is a flowchart showing the processing in the data assembling section 26 of FIG. Data assembler 26
Receives the received information data, checks the transmission time information T in the transmission time information part of the information data, and finds that T <Tb
Then, Tb = T is set (S21). Next, it is checked whether the received packet has been received, that is, whether T ≦ Ta is true or false (S
twenty two). If true, the received packet is discarded (S23). If false, it is checked whether the stored information data includes information data having the same transmission time information (S24).
If there is, the received packet is discarded (S23). If not, the received data is stored (S25). Further, it is determined whether or not there is stored data other than the received data (S26). The time limit of the real-time property is set to Tb-Δ (S27), and it is checked whether or not there is information data that has been waiting longer than the time limit among the stored information data (S28). If there is, the corresponding information data is sent to the receiving application (S29).

[Second Embodiment] FIG. 1B shows a second embodiment of the present invention.
FIG. 4 is a diagram illustrating an embodiment, in which a transmitting terminal 10 is connected to a receiving terminal 11
Information packets 200, 201, 20 using the main connection 12.
2, the information packet 211 is transmitted using the sub-connection 13. In this embodiment, a part of the data transmitted by the main connection 12 is transmitted from the transmitting terminal 10 at the sub-connection 13 with a small time difference from the main connection 12. It is assumed that the information packet 200 has the content of X, 201 has the content of Y, 202 has the content of Z, and the information packet 211 transmitted through the sub-connection 13 has the content of Y.

It is assumed that the packet shown in the right column of FIG. In this case, information packet 20
1 is lost on the way, but since the information data 211 having the same content is received, the receiving terminal 11
All data of Y and Z are obtained. In this embodiment, as described above, the information packet which has a greater effect on the quality in the receiving application is selectively transmitted through the sub-connection. For example, in MPEG2, image information is an I frame,
Although it is transmitted in three types of B frame and P frame,
It is I-frames that have a greater effect on quality.
Therefore, in this case, by transmitting the information of the I-frame through the sub-connection, it is possible to suppress a decrease in quality during image reproduction. Other configurations and processes of the transmitting terminal 10 and the receiving terminal 11 in the second embodiment are the same as those in the first embodiment.

Third Embodiment FIG. 1C shows a third embodiment of the present invention.
FIG. 3 is a diagram illustrating an embodiment, in which a transmitting terminal 10 and a receiving terminal 11 are connected to different LANs via a plurality of relay devices 30 and 32. That is, in this embodiment, the network is composed of the main connection 12, the sub-connection 13,
30, 32 and a relay network 31. In this case, one relay network is used for simplicity. However, the present invention can of course be applied to any configuration including one or more non-guaranteed networks and one or more relay networks interposed therebetween. is there.

In this embodiment, the transmitting terminal 10 is connected to the receiving terminal
11, the information packets 300, 30 are transmitted using the main connection 12.
1, 302 is the information packet 31 using the sub-connection 13.
0, 311, and 312 are transmitted with a small time difference.
In this embodiment, in the sub-connection 13, the concurrent data is temporarily stored in the LIFO type stack and then transmitted. Information packets 300 and 310, 301 and 311 and 302
312 have the contents of X, Y and Z, respectively.

FIG. 9 is a diagram showing a buffer in the relay device 30 or 32. Generally, in a relay device such as a router, information packets are temporarily stored in a buffer having a finite size and processed in the order of arrival (FIFO). If the buffer is full when the information packet arrives at the relay device, the arrived information packet is discarded. Therefore, when a large amount of information packets arrive at the same time, there is a high probability that the last arrived packet will be lost. In this example,
Since the transmission order of the packets in the main connection 12 and the sub connection 13 is reversed by using the LIFO type stack of the transmission terminal 10, as shown in FIG.
302 and 310 are easily lost.

FIG. 2C shows information packets 302 and 310.
An information packet arriving at the receiving terminal 11 when is lost is shown. As can be seen, the receiving terminal has obtained all the information of X, Y and Z. For example, MPE
In a G image frame, an I frame is a B frame or a P frame.
Simultaneity (peakness) is higher than that of the frame. However, as described in the second embodiment, the I frame is the most important information data constituting each frame. This embodiment is effective when the I frame is composed of X, Y and Z information.

FIG. 10 shows a transmitting terminal 10 in this embodiment.
4 is a flowchart showing a process in a sub-connection transmission adjustment unit 23 of FIG. When the sub-connection transmission adjusting unit 23 receives the transmission data from the data transmission unit 22 (S31), the LI
The data is temporarily stored in the FO type stack (S32), and is read out by the LIFO to perform data transmission delay processing (S3).
3), and send it to the sub-connection 13 after processing (S34).

As described above, when data is transmitted almost simultaneously via a relay router, such as a connection between LANs, there is a high probability that data transmitted later will be lost due to buffer overflow. For example, by processing data that occurs simultaneously in the sub-connection in the LIFO type stack, data can be transmitted complementarily to the main connection and the probability of loss can be reduced. Other configurations and processes of the transmitting terminal 10 and the receiving terminal 11 in the third embodiment are the same as those in the first embodiment.

[0024]

As described above, according to the present invention,
When communicating on a communication network in which a non-guaranteed physical network is interposed, it is possible to improve the communication quality (communication performance) of strictly real-time data without adding a special device to the network. Has a remarkable effect.

[Brief description of the drawings]

FIG. 1 is a network diagram for explaining an embodiment of the present invention.

FIG. 2 is a diagram showing a correspondence between a transmission packet and a successfully received packet.

FIG. 3 is a diagram illustrating an example of a configuration of a transmitting terminal and a receiving terminal.

FIG. 4 is a diagram showing an example of a format of an information data packet transmitted to a main connection and a sub connection.

FIG. 5 is a flowchart showing a process in a data transmission unit of the transmission terminal.

FIG. 6 is a flowchart illustrating processing in a sub-connection transmission adjustment unit of a transmission terminal in the first and second embodiments.

FIG. 7 is a reception time chart in the reception terminal.

FIG. 8 is a flowchart showing a process in a data assembling unit of the receiving terminal.

FIG. 9 is a diagram illustrating an operation of a buffer in the relay device.

FIG. 10 is a flowchart illustrating a process in a sub-connection transmission adjustment unit of a transmission terminal according to the third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Sending terminal 11 Receiving terminal 12 Main connection 13 Sub connection 21 Transmission application 22 Data sending part 23 Sub connection transmission adjusting part 24 Main connection data receiving part 25 Sub connection data receiving part 26 Data assembling part 27 Receiving application 30, 32 Relay device 31 Relay network

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Claims (6)

[Claims] When transmitting information data having a strict real-time property to a receiving terminal via at least one non-guaranteed physical network, transmitting the information data using a plurality of communication paths together. A featured real-time communication method. 2. When transmitting information data with strict real-time properties to a receiving terminal via at least one non-guaranteed physical network, a plurality of communication paths are set between the transmitting terminal and the receiving terminal. And transmitting the information data with a slight time difference between the plurality of communication paths. 3. When transmitting information data having strict real-time properties to a receiving terminal via at least one non-guaranteed physical network, a plurality of communication paths are set between the transmitting terminal and the receiving terminal. And transmitting information data by placing a different queue for each of the plurality of communication paths. 4. When transmitting information data with strict real-time properties to a receiving terminal via at least one non-guaranteed physical network, a plurality of communication paths are set between the transmitting terminal and the receiving terminal. And transmitting different information data according to the importance for each of the plurality of communication paths. 5. The information processing apparatus according to claim 1, wherein when information data transmitted by a plurality of communication paths arrives at the receiving terminal, the information data is assembled by synchronizing the plurality of communication paths. 2. The real-time communication method according to claim 1. 6. The real-time communication method according to claim 5, further comprising discarding information data that does not arrive by a predetermined time and information data that has arrived redundantly.