JP2014150451A - Method and system for suppressing deterioration in quality of communication data - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid the state in which a media packet cannot be recovered even when a packet loss is caused by traffic congestion in a network.SOLUTION: According to the present invention, an input packet is distinguished as a media packet and an FEC packet, a flag is set in the media packet and the FEC packet, and occurrence of congestion on a transmission path is determined. When congestion occurs, a packet is selectively abandoned, and a packet that is not abandoned is transferred to a router or a reception device at the next stage.

Description

  The present invention relates to a communication data quality degradation suppressing method and system, and more particularly to forward error correction (FEC) that enables redundant packets to be added to distribution data on the transmission side and loss packet recovery on the reception side in an IP network. The present invention relates to a method and a system for suppressing quality deterioration of communication data in a system for transferring streaming traffic that employs a Forward Error Correction) method.

  In the IP network, when streaming traffic using the FEC method is transmitted, there is a method (Random early detection) in which packets are stochastically discarded according to a discard rate determined according to a queue length (see, for example, Non-Patent Document 1). .

  As shown in FIG. 2, the FEC method encodes a set (hereinafter referred to as a unit) in which FEC packets are added to packets including some video data by using an error correction code, and corrects errors on the receiving side. Detect and correct. In the example of FIG. 2, image data is packetized and FEC encoded. At this time, in order to increase resistance to burst loss, a matrix is created, and a unit is generated by performing a parity operation in the vertical direction. In the parity operation, the FEC packet is obtained and incorporated in the unit as packet [1] XOR packet [2] XOR packet [9] XOR packet [13] = FEC packet [1]. When packet loss occurs in the relay router (packet [3] in the example of FIG. 2), it is detected that congestion has occurred, and the receiving device decodes the received FEC packet and restores the lost packet. .

Sally Folyd, Van Jacobson, "Random early detection gateways for congestion avoidance", IEEE / ACM TRANSACTIONS ON NETWRKING VOL1. No.4. AUGUST 1993.

  However, as shown in FIG. 3A, in general, the FEC method can restore a media packet if the lost packets are distributed to a plurality of units. However, as shown in FIG. When there is a concentration, there is a problem that media packets cannot be restored.

  The present invention has been made in view of the above points, and the quality of communication data that can avoid a state in which a media packet cannot be restored even when packet loss occurs due to traffic congestion in the network. It is an object of the present invention to provide a deterioration suppressing method and system.

In order to solve the above problems, the present invention adds a forward packet to a distribution data on a transmission side in a general IP network, and enables forward error correction (FEC: Forward Error Correction) enabling loss packet restoration on a reception side. ) Communication data quality degradation control method for suppressing quality degradation for streaming traffic adopting the method,
A packet identification step in which the packet identification means identifies the input packet into a media packet and an FEC packet;
A flag setting step for setting a flag in the media packet and the FEC packet;
A congestion state determination means for determining that congestion has occurred on the transmission line; and a congestion state determination step;
A packet discarding step in which a packet discarding unit selectively discards a packet when the congestion occurs; and
The packet transfer means performs a packet transfer step of transferring a packet that has not been discarded to a subsequent router or receiving device.

  As described above, according to the present invention, from the viewpoint that the processing of the redundant packet itself further increases the congestion at the time of congestion, when the traffic increases, the redundant packet is selectively discarded, so that the traffic in the network can be reduced. Even when packet loss occurs due to congestion, it is possible to avoid a state in which the media packet cannot be restored.

It is an example of FEC operation | movement in the case of using a parity code. It is a figure which shows FEC operation | movement in the case of using a parity code. It is a figure which shows the outline | summary in one embodiment of this invention. It is a block diagram of the quality degradation control system in one embodiment of this invention. It is an example of functional arrangement in one embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  First, the outline of the present invention will be described.

  As shown in FIG. 3, according to the present invention, a certain number of FEC packets are always included in each unit. By selectively losing FEC packets, media can be prevented by preventing concentration of lost packets to specific units. This avoids a situation where the packet cannot be restored.

  FIG. 4 shows the configuration of the quality degradation suppression system in one embodiment of the present invention.

  The quality degradation suppressing apparatus shown in FIG. 1 includes a packet identification function unit 1, a flag setting function unit 2, a congestion state determination unit 3, a packet discard function unit 4, and a packet transfer function unit 5.

  The packet identification function unit 1 identifies the FEC packet and the media packet to be transmitted, and outputs them to the flag setting function unit 2.

  The flag setting function unit 2 acquires packet identification information from the packet identification function unit 1 and sets a flag indicating an FEC packet or a media packet. For example, “1” can be set for the FEC packet and “0” can be set for the media packet.

  The congestion state determination unit 3 determines whether or not the link connected to the own device is in a congestion state such as packet loss or duplication. If the link is in the congestion state, the congestion state determination unit 3 notifies the packet discard function unit 4 that there is congestion. If it is not in a congested state, it is output to the queue of the packet transfer function unit 5 as no congestion. In the determination of the congestion state, the congestion state is detected when a certain number of packets are accumulated in the output queue of the device (see, for example, http://www.itbook.info/study/gos4.html).

  The packet discard function unit 4 selectively discards the FEC packet with reference to the flag attached to the packet, and outputs the packet that has not been discarded to the queue of the packet transfer function unit 5.

  The packet transfer function unit 5 transfers the packet existing in the queue to the receiver side.

  FIG. 5 is an example of functional arrangement according to an embodiment of the present invention.

  In the configuration shown in FIG. 4, the packet identification function unit 1 and the flag setting function unit 2 are arranged in the transmission device, and the congestion state determination unit 3, the packet discard function unit 4, and the packet transfer function unit 5 are used as routers that relay packets. It is possible to arrange.

  In FIG. 5, for example, a packet identification function unit 1 and a flag setting function unit 2 are arranged in the transmission device, and a congestion state determination unit 3, a packet discard function unit 4, and a packet transfer function unit 5 are arranged in the router B which is a relay router. Consider the case. In the transmission apparatus, redundant packets including media packets (1 to 16) and FEC packets (1 * to 4 *) as shown in FIG. As shown in FIG. 1, the transmission packet is assumed to have a FEC packet added by performing a parity operation in the vertical direction for each unit. The packet identification function unit 1 notifies the flag setting function unit 2 that the transmission packets 1 to 16 in FIG. 5A are media packets and that 1 * to 4 * are FEC packets. The flag setting function unit 2 sets the flag “0” in the media packet (1 to 16), sets the flag “1” in the FEC packet (1 * to 4 *), and sends it to the router A.

  Router A forwards the packet to router B. When the congestion state determination unit 3 of the router B detects that congestion has occurred with the router C at the next stage, the packet discard function unit 4 of the router B discards 1 * and 4 * of the FEC packets. And output to the packet transfer function unit 5.

  As a result, a packet as shown in FIG. As a result, lost packets are not concentrated in one unit, and the restoration of media packets is not affected, and therefore, it becomes possible to avoid a state where restoration is impossible.

  The present invention is not limited to the above-described embodiment, and various modifications and applications can be made within the scope of the claims.

DESCRIPTION OF SYMBOLS 1 Packet identification function part 2 Flag setting function part 3 Congestion state determination part 4 Packet discard function part 5 Packet transfer function part

Claims (3)

In general IP networks, quality is improved for streaming traffic that uses a forward error correction (FEC) method that adds redundant packets to the distribution data on the transmission side and restores lost packets on the reception side. A communication data quality degradation suppression method for suppressing degradation,
A packet identification step in which the packet identification means identifies the input packet into a media packet and an FEC packet;
A flag setting step for setting a flag in the media packet and the FEC packet;
A congestion state determination means for determining that congestion has occurred on the transmission line; and a congestion state determination step;
A packet discarding step in which a packet discarding unit selectively discards a packet when the congestion occurs; and
A packet forwarding step in which the packet forwarding means forwards a packet that has not been discarded to a router or receiving device at the next stage; and
A method for suppressing deterioration of communication data quality. In general IP networks, quality is improved for streaming traffic that uses a forward error correction (FEC) method that adds redundant packets to the distribution data on the transmission side and restores lost packets on the reception side. A communication data quality deterioration suppression system for suppressing deterioration,
A packet identification means for identifying input packets into media packets and FEC packets;
Flag setting means for setting a flag in the media packet and the FEC packet;
Congestion state determination means for determining that congestion has occurred on the transmission path;
A packet discarding unit for selectively discarding a packet when the congestion occurs;
A packet transfer means for transferring a packet that has not been discarded to the next-stage router or receiving device;
A communication data quality deterioration suppression system characterized by comprising: The packet identification means and the flag setting means are provided in a transmission device,
3. The communication data quality deterioration suppression system according to claim 2, wherein the congestion state determination unit, the packet discard unit, and the packet transfer unit are provided in a relay router.

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