WO2010116616A1 - Relay apparatus and distribution control method of stream distribution system - Google Patents

Relay apparatus and distribution control method of stream distribution system Download PDF

Info

Publication number
WO2010116616A1
WO2010116616A1 PCT/JP2010/001820 JP2010001820W WO2010116616A1 WO 2010116616 A1 WO2010116616 A1 WO 2010116616A1 JP 2010001820 W JP2010001820 W JP 2010001820W WO 2010116616 A1 WO2010116616 A1 WO 2010116616A1
Authority
WO
WIPO (PCT)
Prior art keywords
packet
stream
packet loss
fec
packets
Prior art date
Application number
PCT/JP2010/001820
Other languages
French (fr)
Japanese (ja)
Inventor
谷内田尚司
Original Assignee
日本電気株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 日本電気株式会社 filed Critical 日本電気株式会社
Priority to JP2011508204A priority Critical patent/JPWO2010116616A1/en
Publication of WO2010116616A1 publication Critical patent/WO2010116616A1/en

Links

Images

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/12—Arrangements for detecting or preventing errors in the information received by using return channel
    • H04L1/16—Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
    • H04L1/18—Automatic repetition systems, e.g. Van Duuren systems
    • H04L1/1829—Arrangements specially adapted for the receiver end
    • H04L1/1835—Buffer management
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/12—Arrangements for detecting or preventing errors in the information received by using return channel
    • H04L1/16—Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
    • H04L1/18—Automatic repetition systems, e.g. Van Duuren systems
    • H04L1/1812—Hybrid protocols; Hybrid automatic repeat request [HARQ]
    • H04L1/1819—Hybrid protocols; Hybrid automatic repeat request [HARQ] with retransmission of additional or different redundancy

Definitions

  • the present invention relates to a system that distributes video, audio, and the like in a stream, and particularly relates to a relay apparatus between a transmission apparatus and a reception apparatus and a distribution control method thereof.
  • IPTV Internet Protocol Television
  • IP Internet Protocol
  • a forward error correction (FEC: Forward Error Correction) method that enables redundant data to be added to the delivery data on the transmission side to enable packet loss repair on the reception side. Is adopted.
  • the rate at which errors can be repaired is determined by the redundancy added on the transmission side.
  • the redundancy is defined within a limited range.
  • the redundant code is lengthened, the error resistance is improved, but the delay time for error correction is increased, so that the buffer capacity of the receiving apparatus is increased accordingly and the cost is increased.
  • increasing the buffer capacity on the receiving side also increases the delay time until video playback, so the time from switching the stream to receiving another stream also increases, affecting the quality of service for IPTV viewers. there is a possibility.
  • Patent Document 1 discloses a method for reducing packet loss.
  • the relay device monitors the packet loss state, calculates the optimum redundancy, and requests the upstream relay device / transmission device to respond to the packet loss. It is intended to reduce with good performance.
  • the receiving side notifies the transmitting side of the number of error data calculated using the error correcting code, and the transmitting side determines the information amount of the error correcting code according to the number of error data. Increase or decrease (error correction capability). As a result, communication quality is attempted to be secured without causing an extreme decrease in data throughput.
  • Patent Document 1 since the redundant code is finally transmitted to the receiving device, it is necessary to secure a network band for transmitting the redundant code between the transmitting device and the receiving device. Similarly, in Patent Document 2, since the method of notifying the number of error data from the reception side to the transmission side and increasing or decreasing the error correction capability is adopted, the redundant code is finally transmitted to the reception device. It has a configuration.
  • an object of the present invention is to provide a stream distribution relay apparatus and a stream distribution control method capable of further reducing the network load up to the receiving apparatus and reducing the reproduction delay in the receiving apparatus.
  • a stream distribution relay apparatus is a stream distribution relay apparatus that relays a packet stream distributed with a redundant code and directly transmits the packet stream to a receiving apparatus, and monitors the continuity of received data packets to monitor the packet stream.
  • Packet loss detection means for detecting loss
  • control means for deleting other redundant codes while leaving a redundant code necessary for repairing the packet loss when packet loss is detected.
  • a stream distribution control method is a stream distribution control method for a relay apparatus that relays a packet stream distributed with a redundant code and directly transmits it to a receiving apparatus, and monitors the continuity of received data packets. Then, the packet loss is detected, and when the packet loss is detected, the redundant code necessary for repairing the packet loss is left and other redundant codes are deleted.
  • a stream distribution relay system is a system for multicast distribution of a packet stream distributed with a redundant code added to a plurality of receiving devices through a network, and at least one of the plurality of relay devices in the network.
  • a packet loss detection means for detecting a packet loss by monitoring a continuity of data packets to be directly transmitted to the reception device by a relay device directly connected to the reception device, and when the packet loss is detected, the packet loss Control means for leaving redundant codes necessary for restoration of data and deleting other redundant codes.
  • the present invention it is possible to further reduce the network load up to the receiving device and reduce the reproduction delay in the receiving device.
  • Stream Distribution System An example of a stream distribution system to which an embodiment of the present invention is applied will be described with reference to FIG.
  • video / audio packets from the transmission device 1 are multicast-distributed to a plurality of reception devices 4 through the IP network.
  • On the multicast distribution route there are a relay device 3 that is directly connected to the receiving device 4 and a relay device 2 that is not directly connected to the receiving device 4.
  • the relay device 3 becomes an edge node of the IP network.
  • the relay device according to the present embodiment is applied to the relay device 3 that is an edge node directly connected to the receiving device 4.
  • the transmission apparatus 1 multicast-distributes the IPTV stream S1 in which a predetermined redundant code is added to the IPTV stream packet.
  • the relay device 2 receives the IPTV stream S1
  • the relay device 2 copies the number of packets of the stream by the number of devices (relay devices and / or receiving devices) connected to the downstream side and transmits it downstream.
  • the relay apparatus 3 monitors the continuity of the data packets of the IPTV stream received from the upstream apparatus, and whether packet loss has occurred in the IPTV stream. Monitor whether or not. As will be described later, the relay device 3 removes an unnecessary IPTV stream S3 from which an unnecessary redundant code has been removed if no packet loss has occurred, and an IPTV stream to which a redundant code necessary for restoration has been added if a packet loss has occurred. S3 is transmitted to the directly connected receiving device 4. However, the IPTV stream S1 is copied and transmitted to the relay device connected to the downstream side in the same manner as the relay device 2 described above.
  • the receiving device 4 can repair the lost packet by the arithmetic processing using the packet received from the relay device 3 and the redundant code.
  • the relay device 3 includes a communication interface (I / F) unit 301 and a stream extraction unit 302, is connected to the IP network by the communication I / F unit 301, and is connected to an upstream device (the transmission device 1 or the relay by the stream extraction unit 302).
  • the IPTV stream received from the device is extracted.
  • the extracted IPTV stream packet is temporarily stored in the buffer 303 and simultaneously transferred to the packet duplicating unit 304.
  • the packet duplicating unit 304 copies only the number of devices connected to the downstream side of the received IPTV stream packet (here, two), and sets the distribution address of the packet header to the distribution destination (downstream relay device or reception device). Change to Although the packet addressed to the relay device is stream-transmitted as it is, the packet addressed to the receiving device is transferred to the packet loss detection unit 305.
  • the packet loss detection unit 305 monitors the continuity of the received data packets and detects whether or not a packet loss has occurred. If the data packet is lost from the IPTV stream, the number of the lost packet can be specified from the received packet number.
  • the redundant packet deletion control unit 306 deletes unnecessary redundant codes from the IPTV stream. If a packet loss is detected, the redundant packet deletion control unit 306 is necessary to repair the packet loss from the IPTV stream. Select. The redundant packet deletion control will be described later.
  • the control unit 308 is a program control processor such as a CPU (Central Processing Unit) that controls the overall operation of the relay apparatus 3.
  • the functions of the packet loss detection unit 305 and the redundant packet deletion control unit 306 can also be realized by executing a computer program stored in a storage medium on the program control processor.
  • Redundant packet deletion control Redundant code A case where the forward error correction (FEC) method defined in RFC 2733 is used will be described.
  • the receiving apparatus 4 includes the redundant code FEC a 0 of the FEC packet related to the RTP packets (RTP Pkt0) to (RTP Pkt (L-1)) and the received (L-1) packets.
  • the receiving device 4 restores the lost packet by calculating the XOR of the redundant codes FEC0 to FEC (L-1) and the (D-1) RTP packets received in the column direction. Is possible.
  • the redundant packet deletion control unit 306 of the relay device 3 selects and adds only the FEC packet related to the packet in which the packet loss has occurred based on the arrangement information (association information) of the FEC packet, FEC packets related to RTP packets in which no packet loss has occurred are controlled to be deleted.
  • association information association information
  • step 401 when the communication I / F unit 301 receives an IP packet from the IP network, the stream extraction unit 302 analyzes the header of the received packet and extracts a multicast-distributed stream addressed to the own station.
  • step 402 the control unit 308 transfers the packet of the extracted stream to the packet duplicating unit 304, and the packet duplicating unit 304 copies only the number of devices connected downstream.
  • step 403 the control unit 308 performs different processing on the stream transmitted to the receiving device and the stream transmitted to the relay device.
  • the delivery address of the packet header is changed to the address of the downstream relay device in step 404, and the stream is transmitted to the downstream relay device in step 405.
  • step 406 the control unit 308 transfers the copied stream packet to the packet loss detection unit 305, and the packet loss detection unit 305 determines the continuity of the stream packet.
  • Check For example, in the case of an IPTV service, data communication is performed in accordance with UDP (User Datagram Protocol) / RTP as a communication protocol, so the continuity of “sequence number” in the RTP header is confirmed.
  • UDP User Datagram Protocol
  • packets may be delayed significantly, so they may arrive in a different order from the order of transmission. Therefore, it is possible to temporarily store the received packets in the buffer 303 and rearrange the packets so that the sequence numbers are in ascending order, and check the continuity of the packets.
  • the control unit 308 notifies the redundant packet deletion control unit 306 of the determination result.
  • the redundant packet deletion control unit 306 deletes unnecessary redundant codes from the stream in step 408.
  • the redundant code is added by the FEC method, the FEC packet determined to be unnecessary as described above is deleted. If the packets are discontinuous and there is packet loss (step 407: NO), in step 410, redundant packets necessary for repairing lost packets are selected from the redundant packets included in the stream.
  • the redundant code is added by the FEC method, the FEC packet related to the lost packet is selected as described above.
  • the control unit 308 changes the delivery address of the packet header to the address of the downstream receiving device in step 409, and transmits the stream to the downstream receiving device in step 405.
  • the redundant packet related to the portion having no packet loss is deleted from the stream transmitted from the edge node to the receiving device.
  • Network load can be further reduced. For example, when IPTV service is performed by multicast distribution using FEC, the final network bandwidth called edge one mile from the edge router to each home can be made equal to the bandwidth of the stream that is originally required, and redundant codes are transmitted. It is also possible to obtain the same service quality as that of the service.
  • the receiving device does not distribute the redundant code when no packet loss occurs. For example, the receiving device determines that the redundant code is lost due to the packet loss, and processes the receiving device. There is no need. Furthermore, since the redundant packet related to the portion where there is no packet loss is deleted in the stream transmitted to the receiving device, it is possible to reduce the buffer capacity of the maximum redundant code amount in the receiving device. The delay time from reception to reproduction can be shortened, and the stream switching time can also be shortened.
  • the redundant packet deletion control unit 306 deletes unnecessary redundant codes from the copied stream, and selects only redundant codes necessary for repair of lost packets. However, when the number of lost packets exceeds the number that can be repaired, the receiving device 4 cannot repair the FEC packet even if it is transmitted. Therefore, in the second embodiment of the present invention, packet retransmission means is provided in consideration of a case where the restoration cannot be performed.
  • the relay apparatus 3 As shown in FIG. 5, the relay apparatus 3 according to this embodiment is provided with a packet retransmission request control unit 309 in addition to the configuration of the first embodiment.
  • the buffer 303 may store a packet to be distributed to the receiving device 4, but may store a packet before being copied by the packet copying unit 304.
  • the amount of packets stored in the buffer 303 needs to be larger than the number of packets that can be restored by redundant codes. For example, when the redundant packet array is (20 ⁇ 5), a buffer capacity capable of storing 100 or more packets is required. As described above, only one of the packets used to calculate the redundant code can be repaired with the redundant code, and cannot be repaired when two or more packets are lost. Therefore, in the present embodiment, when the packet loss cannot be repaired, the packet retransmission request control unit 309 requests the transmission apparatus 1 to retransmit the packet.
  • the operation of the relay apparatus 3 according to this embodiment is basically the same as that of the first embodiment shown in FIG. 501-503) are different. Therefore, the same steps as those in the flow shown in FIG. 4 are denoted by the same reference numerals and description thereof is omitted, and steps related to the packet retransmission request control unit 309 will be described.
  • step 501 the control unit 308 determines whether or not the packet loss can be repaired with the FEC packet. judge. If repair is possible (step 501: YES), in step 502, the redundant packet deletion control unit 306 selects a redundant packet necessary for repair from among the redundant packets included in the stream.
  • step 409 the destination of the packet header is The address is changed to the address of the receiving device 4, and the stream is transmitted to the downstream receiving device 4 in step 405.
  • step 503 the packet retransmission request control unit 309 requests the transmitter 1 to retransmit the lost packet.
  • the control unit 308 may insert the packet arrangement corresponding to the buffer 303 into the packet 303 and perform reconfiguration. Further, it may be stored in the buffer 303 so that it can be transmitted when there is a retransmission request of the packet from the receiving device 4.
  • the present invention is applicable to a system and a stream distribution relay device that multicast video and audio streams from a transmission device to a plurality of reception devices.

Abstract

A stream distribution relay apparatus and stream distribution control method which can further reduce the network load up until a reception apparatus and shorten the playback delay at the reception apparatus. The stream distribution relay apparatus relays a packet stream distributed with the addition of redundant codes and directly transmits the packet stream to the reception apparatus. The stream distribution relay apparatus is provided with a packet loss detecting means (305) for monitoring the continuity of received data packets and detecting packet loss, and control means (306, 308) for retaining the redundant codes needed to correct packet loss and deleting the other redundant codes when packet loss has been detected.

Description

ストリーム配信システムにおける中継装置および配信制御方法Relay device and delivery control method in stream delivery system
　本発明は映像や音声などをストリーム配信するシステムに係り、特に送信装置と受信装置との間にある中継装置およびその配信制御方法に関する。 The present invention relates to a system that distributes video, audio, and the like in a stream, and particularly relates to a relay apparatus between a transmission apparatus and a reception apparatus and a distribution control method thereof.
　近年、電話線を利用した高速デジタルデータ通信技術(ｘＤＳＬ: x Digital Subscriber Line)や光ファイバーを利用した家庭向けのデータ通信サービス(ＦＴＴＨ：Fiber To The Home)等の普及によって各家庭でも高画質映像を楽しむ事が出来るようになってきた。特に、高画質映像配信サービスの中でもＩＰ(Internet Protocol)を利用してデジタルテレビ放送を配信するＩＰＴＶ(Internet Protocol Television)サービスが注目されている。ＩＰＴＶサービスは、マルチキャストによるネットワーク配信技術を用い、送信装置から出力されるストリームを中継装置にてコピーし、複数の受信装置に効率良く配信するサービスである。特に、ＩＰＴＶサービスのようなリアルタイム性が必要なストリーミング配信サービスでは、送信側で配信データに冗長符号を付加し受信側でのパケットロス修復を可能にする前方誤り訂正（ＦＥＣ：Forward Error Correction）方式が採用されている。 In recent years, high-speed digital data communication technology using telephone lines (xDSL: x Digital Subscriber Line) and data communication services for homes using optical fibers (FTTH: Fiber To The Home) etc. I can now enjoy it. In particular, IPTV (Internet Protocol Television) service that distributes digital television broadcasting using IP (Internet Protocol) is attracting attention among high-quality video distribution services. The IPTV service is a service that uses a network distribution technique based on multicast, copies a stream output from a transmission device by a relay device, and efficiently distributes the stream to a plurality of reception devices. In particular, in a streaming delivery service that requires real-time performance, such as an IPTV service, a forward error correction (FEC: Forward Error Correction) method that enables redundant data to be added to the delivery data on the transmission side to enable packet loss repair on the reception side. Is adopted.
　ＦＥＣ方式では、送信側で付加する冗長度によってエラーを修復できるレートが決まってくる。エラー耐性を強固にするには冗長符号を増加させる必要があるが、ＩＰＴＶサービスでは冗長度が限られた範囲内で定義されている。冗長符号を長くするとエラー耐性は良くなるが、エラー修復のための遅延時間が増大するので、それだけ受信装置のバッファ容量が増加しコスト増加につながる。更に、受信側のバッファ容量の増大は、映像再生までの遅延時間も増加するので、ストリームを切替えてから別のストリームを受信するまでの時間も増加し、ＩＰＴＶ視聴者に対するサービス品質に影響を与える可能性がある。 In the FEC method, the rate at which errors can be repaired is determined by the redundancy added on the transmission side. In order to increase error resistance, it is necessary to increase the number of redundant codes, but in the IPTV service, the redundancy is defined within a limited range. When the redundant code is lengthened, the error resistance is improved, but the delay time for error correction is increased, so that the buffer capacity of the receiving apparatus is increased accordingly and the cost is increased. Furthermore, increasing the buffer capacity on the receiving side also increases the delay time until video playback, so the time from switching the stream to receiving another stream also increases, affecting the quality of service for IPTV viewers. there is a possibility.
　そこで、パケットロスを低減させる方法が特許文献１に開示されている。この方法は、ＦＥＣを用いたマルチキャスト配信において、中継装置がパケットロス状態を監視して最適の冗長度を計算し、それを上流の中継装置／送信装置に対して要求することでパケットロスを応答性良く低減させようとするものである。 Therefore, Patent Document 1 discloses a method for reducing packet loss. In this method, in multicast distribution using FEC, the relay device monitors the packet loss state, calculates the optimum redundancy, and requests the upstream relay device / transmission device to respond to the packet loss. It is intended to reduce with good performance.
　また、特許文献２に開示されたデータ転送システムによれば、受信側が誤り訂正符号を用いて計算した誤りデータ数を送信側へ通知し、送信側が誤りデータ数に応じて誤り訂正符号の情報量（誤り訂正能力）を増減する。これにより、データスループットの極端な低下を招くことなく通信品質を確保しようとする。 Further, according to the data transfer system disclosed in Patent Document 2, the receiving side notifies the transmitting side of the number of error data calculated using the error correcting code, and the transmitting side determines the information amount of the error correcting code according to the number of error data. Increase or decrease (error correction capability). As a result, communication quality is attempted to be secured without causing an extreme decrease in data throughput.
特開２００６－１７４２９８号公報JP 2006-174298 A 特開２００５－３０３４９５号公報JP 2005-303495 A
　しかしながら、特許文献１では、冗長符号が最終的に受信装置まで送信されるため、送信装置から受信装置までの間で冗長符号を送信するためのネットワーク帯域を確保する必要がある。また、特許文献２においても同様に、受信側から送信側へ誤りデータ数を通知して誤り訂正能力を増減させる方法を採用しているために、冗長符号が最終的に受信装置まで送信される構成となっている。 However, in Patent Document 1, since the redundant code is finally transmitted to the receiving device, it is necessary to secure a network band for transmitting the redundant code between the transmitting device and the receiving device. Similarly, in Patent Document 2, since the method of notifying the number of error data from the reception side to the transmission side and increasing or decreasing the error correction capability is adopted, the redundant code is finally transmitted to the reception device. It has a configuration.
　さらに、受信装置ではＦＥＣ方式によるパケットロス修復のための冗長度が決められていないので、冗長符号量の最大値のバッファ容量を持つ必要がある。このために、上述した特許文献１および２では、受信装置がストリームを受信してから映像出力するまでの遅延時間は改善されず、ストリーム切り替え時間も短縮できないという問題があった。 Furthermore, since the redundancy for packet loss restoration by the FEC method is not determined in the receiving apparatus, it is necessary to have a buffer capacity with a maximum redundant code amount. For this reason, in Patent Documents 1 and 2 described above, there is a problem in that the delay time from when the receiving apparatus receives a stream until the video is output is not improved, and the stream switching time cannot be shortened.
　そこで、本発明の目的は、受信装置までのネットワーク負荷をより軽減すると共に受信装置での再生遅延を短縮することができるストリーム配信中継装置およびストリーム配信制御方法を提供することにある。 Therefore, an object of the present invention is to provide a stream distribution relay apparatus and a stream distribution control method capable of further reducing the network load up to the receiving apparatus and reducing the reproduction delay in the receiving apparatus.
　本発明によるストリーム配信中継装置は、冗長符号を付加して配信されたパケットストリームを中継して受信装置へ直接送信するストリーム配信中継装置であって、受信したデータパケットの連続性を監視してパケット消失を検出するパケットロス検出手段と、パケット消失が検出されたときに当該パケット消失の修復に必要な冗長符号を残し他の冗長符号を削除する制御手段と、を有することを特徴とする。 A stream distribution relay apparatus according to the present invention is a stream distribution relay apparatus that relays a packet stream distributed with a redundant code and directly transmits the packet stream to a receiving apparatus, and monitors the continuity of received data packets to monitor the packet stream. Packet loss detection means for detecting loss, and control means for deleting other redundant codes while leaving a redundant code necessary for repairing the packet loss when packet loss is detected.
　本発明によるストリーム配信制御方法は、冗長符号を付加して配信されたパケットストリームを中継して受信装置へ直接送信する中継装置のストリーム配信制御方法であって、受信したデータパケットの連続性を監視してパケット消失を検出し、パケット消失が検出されたときに当該パケット消失の修復に必要な冗長符号を残し他の冗長符号を削除する、ことを特徴とする。 A stream distribution control method according to the present invention is a stream distribution control method for a relay apparatus that relays a packet stream distributed with a redundant code and directly transmits it to a receiving apparatus, and monitors the continuity of received data packets. Then, the packet loss is detected, and when the packet loss is detected, the redundant code necessary for repairing the packet loss is left and other redundant codes are deleted.
　本発明によるストリーム配信中継システムは、冗長符号を付加して配信されたパケットストリームをネットワークを通して複数の受信装置へマルチキャスト配信するシステムであって、前記ネットワーク内の複数の中継装置のうち、少なくとも１つの受信装置に直接接続された中継装置が、前記受信装置へ直接送信すべきデータパケットの連続性を監視してパケット消失を検出するパケットロス検出手段と、パケット消失が検出されたときに当該パケット消失の修復に必要な冗長符号を残し他の冗長符号を削除する制御手段と、を有することを特徴とする。 A stream distribution relay system according to the present invention is a system for multicast distribution of a packet stream distributed with a redundant code added to a plurality of receiving devices through a network, and at least one of the plurality of relay devices in the network. A packet loss detection means for detecting a packet loss by monitoring a continuity of data packets to be directly transmitted to the reception device by a relay device directly connected to the reception device, and when the packet loss is detected, the packet loss Control means for leaving redundant codes necessary for restoration of data and deleting other redundant codes.
　本発明によれば、受信装置までのネットワーク負荷をより軽減すると共に受信装置での再生遅延を短縮することができる。 According to the present invention, it is possible to further reduce the network load up to the receiving device and reduce the reproduction delay in the receiving device.
本発明によるストリーム配信システムの概略を説明するためのネットワーク図である。It is a network diagram for demonstrating the outline of the stream delivery system by this invention. 本発明の第一実施形態によるストリーム配信中継装置の機能的構成を示すブロック図である。It is a block diagram which shows the functional structure of the stream delivery relay apparatus by 1st embodiment of this invention. 第一実施形態におけるＦＥＣパケット削除処理を説明するための模式図である。It is a schematic diagram for demonstrating the FEC packet deletion process in 1st embodiment. 第一実施形態によるストリーム配信中継装置における配信制御方法の動作手順を示すフローチャートである。It is a flowchart which shows the operation | movement procedure of the delivery control method in the stream delivery relay apparatus by 1st embodiment. 本発明の第二実施形態によるストリーム配信中継装置の機能的構成を示すブロック図である。It is a block diagram which shows the functional structure of the stream delivery relay apparatus by 2nd embodiment of this invention. 第二実施形態によるストリーム配信中継装置における配信制御方法の動作手順を示すフローチャートである。It is a flowchart which shows the operation | movement procedure of the delivery control method in the stream delivery relay apparatus by 2nd embodiment.
　以下、本発明を実施するための形態について図面を参照して詳細に説明する。なお、本発明は、以下に述べる実施形態により限定されるものではない。 Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by embodiment described below.
　１．ストリーム配信システム
　図１を用いて、本発明の実施形態を適用するストリーム配信システムの一例を説明する。このシステムでは、送信装置１から映像・音声パケットがＩＰネットワークを通して複数の受信装置４へマルチキャスト配信される。このマルチキャスト配信の経路上に、受信装置４に直接接続された中継装置３と、受信装置４に直接接続されていない中継装置２とがある。中継装置３はＩＰネットワークのエッジノードとなる。本実施形態による中継装置は、受信装置４に直接接続されたエッジノードである中継装置３に適用される。 1. Stream Distribution System An example of a stream distribution system to which an embodiment of the present invention is applied will be described with reference to FIG. In this system, video / audio packets from the transmission device 1 are multicast-distributed to a plurality of reception devices 4 through the IP network. On the multicast distribution route, there are a relay device 3 that is directly connected to the receiving device 4 and a relay device 2 that is not directly connected to the receiving device 4. The relay device 3 becomes an edge node of the IP network. The relay device according to the present embodiment is applied to the relay device 3 that is an edge node directly connected to the receiving device 4.
　送信装置１は、ＩＰＴＶストリームパケットに予め決められた冗長符号を付加したＩＰＴＶストリームＳ１をマルチキャスト配信する。中継装置２は、ＩＰＴＶストリームＳ１を受信すると、そのストリームのパケットを下流側に接続された装置（中継装置および／または受信装置）の個数分だけコピーして下流へ送信する。 The transmission apparatus 1 multicast-distributes the IPTV stream S1 in which a predetermined redundant code is added to the IPTV stream packet. When the relay device 2 receives the IPTV stream S1, the relay device 2 copies the number of packets of the stream by the number of devices (relay devices and / or receiving devices) connected to the downstream side and transmits it downstream.
　中継装置３は、下流側に直接接続された受信装置４への配信であれば、上流の装置から受信したＩＰＴＶストリームのデータパケットの連続性を監視し、ＩＰＴＶストリームにパケットロスが発生しているか否かを監視する。中継装置３は、後述するように、パケットロスが発生していなければ不要な冗長符号を外したＩＰＴＶストリームＳ３を、パケットロスが発生していれば修復に必要な冗長符号が付加されたＩＰＴＶストリームＳ３を、直接接続された受信装置４へ送信する。ただし、下流側に接続された中継装置に対しては、上述した中継装置２と同様にＩＰＴＶストリームＳ１をコピーして送信する。 If the relay apparatus 3 distributes to the receiving apparatus 4 directly connected to the downstream side, the relay apparatus 3 monitors the continuity of the data packets of the IPTV stream received from the upstream apparatus, and whether packet loss has occurred in the IPTV stream. Monitor whether or not. As will be described later, the relay device 3 removes an unnecessary IPTV stream S3 from which an unnecessary redundant code has been removed if no packet loss has occurred, and an IPTV stream to which a redundant code necessary for restoration has been added if a packet loss has occurred. S3 is transmitted to the directly connected receiving device 4. However, the IPTV stream S1 is copied and transmitted to the relay device connected to the downstream side in the same manner as the relay device 2 described above.
　受信装置４は、パケットロスが発生したストリームを受信しても、中継装置３から受信したパケットと冗長符号とを用いた演算処理により消失したパケットを修復することができる。 Even if the receiving device 4 receives the stream in which the packet loss has occurred, the receiving device 4 can repair the lost packet by the arithmetic processing using the packet received from the relay device 3 and the redundant code.
　２．第一実施形態
　２．１）構成
　次に、図２を参照しながら、本発明の第一実施形態に係るストリーム配信中継装置の機能構成について説明する。ただし、ここでは後段に中継装置および受信装置４が接続されている中継装置３を例示するが、他の中継装置でも基本的構成は同じである。 2. First Embodiment 2.1) Configuration Next, the functional configuration of the stream distribution relay device according to the first embodiment of the present invention will be described with reference to FIG. However, here, the relay device 3 in which the relay device and the receiving device 4 are connected in the subsequent stage is illustrated, but the basic configuration is the same in other relay devices.
　中継装置３は、通信インタフェース（Ｉ／Ｆ）部３０１およびストリーム抽出部３０２を有し、通信Ｉ／Ｆ部３０１によりＩＰネットワークに接続され、ストリーム抽出部３０２によって上流の装置（送信装置１あるいは中継装置）から受信したＩＰＴＶストリームを抽出する。 The relay device 3 includes a communication interface (I / F) unit 301 and a stream extraction unit 302, is connected to the IP network by the communication I / F unit 301, and is connected to an upstream device (the transmission device 1 or the relay by the stream extraction unit 302). The IPTV stream received from the device is extracted.
　抽出されたＩＰＴＶストリームのパケットはバッファ３０３に一時格納されると同時に、パケット複製部３０４へ転送される。パケット複製部３０４は、受信したＩＰＴＶストリームのパケットを下流側に接続された装置数（ここでは２個）だけをコピーし、それぞれパケットヘッダの配信アドレスを配信先（下流の中継装置あるいは受信装置）に変更する。中継装置宛のパケットはそのままストリーム送信されるが、受信装置宛のパケットはパケットロス検出部３０５へ転送される。 The extracted IPTV stream packet is temporarily stored in the buffer 303 and simultaneously transferred to the packet duplicating unit 304. The packet duplicating unit 304 copies only the number of devices connected to the downstream side of the received IPTV stream packet (here, two), and sets the distribution address of the packet header to the distribution destination (downstream relay device or reception device). Change to Although the packet addressed to the relay device is stream-transmitted as it is, the packet addressed to the receiving device is transferred to the packet loss detection unit 305.
　パケットロス検出部３０５は受信したデータパケットの連続性を監視し、パケットロスの発生の有無を検出する。ＩＰＴＶストリームからデータパケットが消失していれば、受信したパケットの番号から当該消失パケットの番号を特定することができる。 The packet loss detection unit 305 monitors the continuity of the received data packets and detects whether or not a packet loss has occurred. If the data packet is lost from the IPTV stream, the number of the lost packet can be specified from the received packet number.
　冗長パケット削除制御部３０６は、パケットロスが検出されなければ、ＩＰＴＶストリームから不要な冗長符号を削除し、パケットロスが検出された場合にはＩＰＴＶストリームからパケットロスを修復するために必要な冗長符号を選択する。冗長パケット削除制御については後述する。 If no packet loss is detected, the redundant packet deletion control unit 306 deletes unnecessary redundant codes from the IPTV stream. If a packet loss is detected, the redundant packet deletion control unit 306 is necessary to repair the packet loss from the IPTV stream. Select. The redundant packet deletion control will be described later.
　こうして、不要な冗長符号が削除され必要な冗長符号だけを付加したＩＰＴＶストリームが通信Ｉ／Ｆ部３０７を通して受信装置４へ送信される。制御部３０８は中継装置３の全体的な動作を制御するＣＰＵ(Central Processing Unit)等のプログラム制御プロセッサである。なお、パケットロス検出部３０５および冗長パケット削除制御部３０６の機能もプログラム制御プロセッサ上で、記憶媒体に格納されたコンピュータプログラムを実行することにより実現可能である
　２．２）冗長パケット削除制御
　冗長符号としてＲＦＣ２７３３で規定されている前方誤り訂正（ＦＥＣ）方式を用いる場合を説明する。 Thus, an IPTV stream to which unnecessary redundant codes are deleted and only necessary redundant codes are added is transmitted to the receiving device 4 through the communication I / F unit 307. The control unit 308 is a program control processor such as a CPU (Central Processing Unit) that controls the overall operation of the relay apparatus 3. The functions of the packet loss detection unit 305 and the redundant packet deletion control unit 306 can also be realized by executing a computer program stored in a storage medium on the program control processor. 2.2) Redundant packet deletion control Redundant code A case where the forward error correction (FEC) method defined in RFC 2733 is used will be described.
　図３に示すように、（Ｄ×Ｌ）個のＲＴＰ(Real-time Transport Protocol)パケット（ＲＴＰ　Ｐｋｔ（ｉ））を順にＤ行×Ｌ列に配列したときに、各行のＬ個のパケットデータの排他的論理和ＸＯＲがそれぞれ行方向の冗長符号ＦＥＣａ０～ＦＥＣａ（Ｄ－１）となり、各列のＤ個のパケットデータの排他的論理和ＸＯＲがそれぞれ列方向の冗長符号ＦＥＣ０～ＦＥＣ（Ｌ－１）となる。したがって、送信装置１は（Ｄ×Ｌ）個のＲＴＰパケットに対して（Ｄ＋Ｌ）個のＦＥＣパケットを付加して配信する。このようなパケットを受信した受信装置４でのＦＥＣ動作は次のようになる。 As shown in FIG. 3, when (D × L) RTP (Real-time Transport Protocol) packets (RTP Pkt (i)) are sequentially arranged in D rows × L columns, L packet data in each row Becomes the redundant codes FEC a 0 to FEC a (D-1) in the row direction, respectively, and the exclusive OR XOR of the D packet data in each column becomes the redundant codes FEC0 to FEC in the column direction, respectively. (L-1). Therefore, the transmission apparatus 1 adds (D + L) FEC packets to (D × L) RTP packets and distributes them. The FEC operation in the receiving apparatus 4 that has received such a packet is as follows.
　一例として、送信されたＲＴＰパケット（ＲＴＰ　Ｐｋｔ０）～（ＲＴＰ　Ｐｋｔ（Ｌ－１））にパケットロスがランダムに発生し、受信側ではＲＴＰパケット（ＲＴＰ　Ｐｋｔ１）が消失していたとする。この場合、受信装置４は、ＲＴＰパケット（ＲＴＰ　Ｐｋｔ０）～（ＲＴＰ　Ｐｋｔ（Ｌ－１））に関係づけられたＦＥＣパケットの冗長符号ＦＥＣａ０と、受信された（Ｌ－１）個のパケット（ＲＴＰ　Ｐｋｔ０）、（ＲＴＰ　Ｐｋｔ２）～（ＲＴＰ　Ｐｋｔ（Ｌ－１））との排他的論理和ＸＯＲを演算することにより、消失したパケット（ＲＴＰ　Ｐｋｔ１）を復元することが可能となる。 As an example, it is assumed that packet loss occurs randomly in the transmitted RTP packets (RTP Pkt0) to (RTP Pkt (L-1)), and the RTP packet (RTP Pkt1) is lost on the receiving side. In this case, the receiving apparatus 4 includes the redundant code FEC a 0 of the FEC packet related to the RTP packets (RTP Pkt0) to (RTP Pkt (L-1)) and the received (L-1) packets. By calculating an exclusive OR XOR with (RTP Pkt0) and (RTP Pkt2) to (RTP Pkt (L-1)), it is possible to restore the lost packet (RTP Pkt1).
　また、（Ｄ×Ｌ）個のパケットのうちＬ個以下のパケットロスが連続的に発生すると、列方向のＤ個のパケットのうち１個のパケットが消失したことと同等となる。この場合、受信装置４は、冗長符号ＦＥＣ０～ＦＥＣ（Ｌ－１）と列方向で受信された（Ｄ－１）個のＲＴＰパケットとのＸＯＲを演算することで、消失したパケットを復元することが可能となる。 Also, if L or less packet losses occur continuously among (D × L) packets, this is equivalent to the loss of one packet among the D packets in the column direction. In this case, the receiving device 4 restores the lost packet by calculating the XOR of the redundant codes FEC0 to FEC (L-1) and the (D-1) RTP packets received in the column direction. Is possible.
　このように（Ｄ×Ｌ）個のＲＴＰパケットに対して付加されるＦＥＣパケットは（Ｄ＋Ｌ）個となる。したがって、もし（Ｄ×Ｌ）個のＲＴＰパケットが全て完全に受信された場合には（Ｄ＋Ｌ）個のＦＥＣパケットは無駄となり、ネットワーク帯域をいたずらに消費していることになる。 In this way, the number of FEC packets added to (D × L) RTP packets is (D + L). Therefore, if (D × L) RTP packets are completely received, (D + L) FEC packets are wasted, and the network bandwidth is consumed unnecessarily.
　そこで、本実施形態による中継装置３の冗長パケット削除制御部３０６は、ＦＥＣパケットの配列情報（関係づけ情報）に基づいて、パケットロスが発生したパケットに関連するＦＥＣパケットのみ選択して付加し、パケットロスが発生していないＲＴＰパケットに関連するＦＥＣパケットは削除する制御を行っている。以下、中継装置３の動作をより詳細に説明する。 Therefore, the redundant packet deletion control unit 306 of the relay device 3 according to the present embodiment selects and adds only the FEC packet related to the packet in which the packet loss has occurred based on the arrangement information (association information) of the FEC packet, FEC packets related to RTP packets in which no packet loss has occurred are controlled to be deleted. Hereinafter, the operation of the relay device 3 will be described in more detail.
　２．３）動作
　次に図４を参照しながら、本発明の第一実施形態に係るストリーム配信中継装置の動作をフローチャートに基づいて説明する。 2.3) Operation Next, the operation of the stream distribution relay device according to the first embodiment of the present invention will be described based on a flowchart with reference to FIG.
　ステップ４０１において、通信Ｉ／Ｆ部３０１がＩＰネットワークからＩＰパケットを受信すると、ストリーム抽出部３０２が受信パケットのヘッダを解析し、自局宛のマルチキャスト配信されたストリームを抽出する。 In step 401, when the communication I / F unit 301 receives an IP packet from the IP network, the stream extraction unit 302 analyzes the header of the received packet and extracts a multicast-distributed stream addressed to the own station.
　ステップ４０２において、制御部３０８は、抽出されたストリームのパケットをパケット複製部３０４へ転送し、パケット複製部３０４がパケットを下流に接続されている装置数分だけをコピーする。 In step 402, the control unit 308 transfers the packet of the extracted stream to the packet duplicating unit 304, and the packet duplicating unit 304 copies only the number of devices connected downstream.
　ステップ４０３において、制御部３０８は、受信装置へ送信するストリームと中継装置へ送信するストリームとに対して異なる処理を実行する。 In step 403, the control unit 308 performs different processing on the stream transmitted to the receiving device and the stream transmitted to the relay device.
　まず、下流への送信先が中継装置の場合には、ステップ４０４においてパケットヘッダの配信アドレスを下流の中継装置のアドレスに変更し、ステップ４０５において当該ストリームを下流の中継装置へ送信する。 First, if the downstream transmission destination is a relay device, the delivery address of the packet header is changed to the address of the downstream relay device in step 404, and the stream is transmitted to the downstream relay device in step 405.
　下流への送信先が受信装置４の場合には、ステップ４０６において、制御部３０８がコピーされたストリームパケットをパケットロス検出部３０５へ転送し、パケットロス検出部３０５が当該ストリームパケットの連続性を確認する。例えば、ＩＰＴＶサービスの場合には通信プロトコルとしてＵＤＰ(User Datagram Protocol)／ＲＴＰに従いデータ通信を行っているため、ＲＴＰヘッダの”sequence number”の連続性を確認する。 When the downstream transmission destination is the receiving device 4, in step 406, the control unit 308 transfers the copied stream packet to the packet loss detection unit 305, and the packet loss detection unit 305 determines the continuity of the stream packet. Check. For example, in the case of an IPTV service, data communication is performed in accordance with UDP (User Datagram Protocol) / RTP as a communication protocol, so the continuity of “sequence number” in the RTP header is confirmed.
　なお、パケットによっては大きく遅延する場合があるので、送信時の順序とは異なった順番で到着することもある。そこで、受信パケットをバッファ３０３に一旦蓄積し、たとえばシーケンス番号が昇順となるように並べ替えてからパケットの連続性を確認することも可能である。 Note that some packets may be delayed significantly, so they may arrive in a different order from the order of transmission. Therefore, it is possible to temporarily store the received packets in the buffer 303 and rearrange the packets so that the sequence numbers are in ascending order, and check the continuity of the packets.
　こうしてパケットロス検出部３０５がステップ４０７においてパケットが連続であるか否かを判定すると、制御部３０８はその判定結果を冗長パケット削除制御部３０６へ通知する。 Thus, when the packet loss detection unit 305 determines in step 407 whether or not the packets are continuous, the control unit 308 notifies the redundant packet deletion control unit 306 of the determination result.
　冗長パケット削除制御部３０６は、パケットが連続でパケットロスがない場合（ステップ４０７：ＹＥＳ）には、ステップ４０８においてストリームから不要な冗長符合を削除する。冗長符号がＦＥＣ方式により付加されている場合には、上述したように不要と判断されたＦＥＣパケットを削除する。パケットが不連続でパケットロスがある場合（ステップ４０７：ＮＯ）には、ステップ４１０において、ストリームに含まれる冗長パケットの中から、消失したパケットを修復するために必要な冗長パケットを選択する。冗長符号がＦＥＣ方式により付加されている場合には、上述したように消失したパケットに関連するＦＥＣパケットを選択する。 When the packets are continuous and there is no packet loss (step 407: YES), the redundant packet deletion control unit 306 deletes unnecessary redundant codes from the stream in step 408. When the redundant code is added by the FEC method, the FEC packet determined to be unnecessary as described above is deleted. If the packets are discontinuous and there is packet loss (step 407: NO), in step 410, redundant packets necessary for repairing lost packets are selected from the redundant packets included in the stream. When the redundant code is added by the FEC method, the FEC packet related to the lost packet is selected as described above.
　こうして、下流への送信先が受信装置の場合には、コピーされたストリームから不要な冗長符号を削除し、必要な冗長符号だけを選択して残すように冗長パケット削除制御が実装される。そして、制御部３０８は、ステップ４０９においてパケットヘッダの配信アドレスを下流の受信装置のアドレスに変更し、ステップ４０５において当該ストリームを下流の受信装置へ送信する。 Thus, when the downstream transmission destination is the receiving apparatus, redundant packet deletion control is implemented so that unnecessary redundant codes are deleted from the copied stream and only necessary redundant codes are selected and left. Then, the control unit 308 changes the delivery address of the packet header to the address of the downstream receiving device in step 409, and transmits the stream to the downstream receiving device in step 405.
　２．４）効果
　上述したように、本発明の第一実施形態によれば、エッジノードから受信装置へ送信されるストリームにはパケットロスがない部分に関係する冗長パケットが削除されているので、ネットワーク負荷をより軽減することができる。たとえばＦＥＣを適用したマルチキャスト配信によってＩＰＴＶサービスを行う際に、エッジルータから各家庭へのラストワンマイルといわれる最終のネットワークの帯域を本来必要なストリームの帯域並にすることができ、且つ冗長符号を伝送しているのと同等なサービス品質を確保することができる、という効果も得られる。 2.4) Effect As described above, according to the first embodiment of the present invention, the redundant packet related to the portion having no packet loss is deleted from the stream transmitted from the edge node to the receiving device. Network load can be further reduced. For example, when IPTV service is performed by multicast distribution using FEC, the final network bandwidth called edge one mile from the edge router to each home can be made equal to the bandwidth of the stream that is originally required, and redundant codes are transmitted. It is also possible to obtain the same service quality as that of the service.
　また、受信装置は、パケットロスが発生していない場合に冗長符号が配信されなくなるが、例えば冗長符号がパケットロスによって失われていると判断し処理すればよいため、受信装置に何ら手を加える必要はない。さらに、受信装置へ送信されるストリームにはパケットロスがない部分に関係する冗長パケットが削除されているので、受信装置において冗長符号量の最大値のバッファ容量を低減させることが可能となり、ストリームを受信してから再生するまでの遅延時間を短縮することができ、ストリーム切り替え時間も短縮可能となる。 In addition, the receiving device does not distribute the redundant code when no packet loss occurs. For example, the receiving device determines that the redundant code is lost due to the packet loss, and processes the receiving device. There is no need. Furthermore, since the redundant packet related to the portion where there is no packet loss is deleted in the stream transmitted to the receiving device, it is possible to reduce the buffer capacity of the maximum redundant code amount in the receiving device. The delay time from reception to reproduction can be shortened, and the stream switching time can also be shortened.
　３．第二実施形態
　上述した第一実施形態では、冗長パケット削除制御部３０６がコピーされたストリームから不要な冗長符号を削除し、消失パケットの修復に必要な冗長符号だけを選択している。しかしながら、消失パケット数が修復可能な数を超えた場合には、ＦＥＣパケットを送信しても受信装置４で修復することはできない。そこで、本発明の第二実施形態では、修復できない場合を考慮してパケット再送手段を設けている。 3. Second Embodiment In the first embodiment described above, the redundant packet deletion control unit 306 deletes unnecessary redundant codes from the copied stream, and selects only redundant codes necessary for repair of lost packets. However, when the number of lost packets exceeds the number that can be repaired, the receiving device 4 cannot repair the FEC packet even if it is transmitted. Therefore, in the second embodiment of the present invention, packet retransmission means is provided in consideration of a case where the restoration cannot be performed.
　図５に示すように、本実施形態による中継装置３には、第一実施形態の構成に加えて、パケット再送要求制御部３０９が設けられている。その他の構成および機能は、図２に示す第一実施形態と同様であるから、同一の参照番号を付して説明は省略する。ただし、バッファ３０３は、受信装置４に配信するパケットを蓄積してもよいが、パケット複製部３０４でコピーする前のパケットを蓄積してもよい。 As shown in FIG. 5, the relay apparatus 3 according to this embodiment is provided with a packet retransmission request control unit 309 in addition to the configuration of the first embodiment. Other configurations and functions are the same as those of the first embodiment shown in FIG. However, the buffer 303 may store a packet to be distributed to the receiving device 4, but may store a packet before being copied by the packet copying unit 304.
　バッファ３０３でのパケット蓄積量は冗長符号により復元できるパケット数以上のバッファが必要である。例えば、冗長パケットの配列が（２０×５）の場合には１００パケット以上蓄積できるバッファ容量が必要となる。先に述べた通り、冗長符号で修復できるパケットは、冗長符号を算出するのに使用したパケットの内１つのみであり、２つ以上パケットが消失すると修復できない。そこで、本実施形態では、パケット消失を修復できない場合にパケット再送要求制御部３０９がパケット再送を送信装置１に要求するようにしている。 The amount of packets stored in the buffer 303 needs to be larger than the number of packets that can be restored by redundant codes. For example, when the redundant packet array is (20 × 5), a buffer capacity capable of storing 100 or more packets is required. As described above, only one of the packets used to calculate the redundant code can be repaired with the redundant code, and cannot be repaired when two or more packets are lost. Therefore, in the present embodiment, when the packet loss cannot be repaired, the packet retransmission request control unit 309 requests the transmission apparatus 1 to retransmit the packet.
　図６に示すように、本実施形態による中継装置３の動作は、基本的には図４に示す第一実施形態の場合と同様であるが、パケット再送要求制御部３０９が関係する動作（ステップ５０１－５０３）が異なっている。そこで、図４に示すフローと同一のステップには同一の参照番号を付して説明は省略し、パケット再送要求制御部３０９が関係するステップについて説明する。 As shown in FIG. 6, the operation of the relay apparatus 3 according to this embodiment is basically the same as that of the first embodiment shown in FIG. 501-503) are different. Therefore, the same steps as those in the flow shown in FIG. 4 are denoted by the same reference numerals and description thereof is omitted, and steps related to the packet retransmission request control unit 309 will be described.
　ステップ４０７において連続性の判定が行われ、パケットが不連続でパケットロスがある場合（ステップ４０７：ＮＯ）には、ステップ５０１において、制御部３０８はパケットロスがＦＥＣパケットで修復可能か否かを判定する。修復可能であれば（ステップ５０１：ＹＥＳ）、ステップ５０２において、冗長パケット削除制御部３０６がストリームに含まれる冗長パケットの中から修復に必要な冗長パケットを選択し、ステップ４０９においてパケットヘッダの宛先が受信装置４のアドレスに変更され、ステップ４０５において当該ストリームが下流の受信装置４へ送信される。 If the continuity is determined in step 407 and the packet is discontinuous and there is a packet loss (step 407: NO), in step 501, the control unit 308 determines whether or not the packet loss can be repaired with the FEC packet. judge. If repair is possible (step 501: YES), in step 502, the redundant packet deletion control unit 306 selects a redundant packet necessary for repair from among the redundant packets included in the stream. In step 409, the destination of the packet header is The address is changed to the address of the receiving device 4, and the stream is transmitted to the downstream receiving device 4 in step 405.
　修復できない場合には（ステップ５０１：ＮＯ）、ステップ５０３において、パケット再送要求制御部３０９が送信装置１に対して消失したパケットの再送信を要求する。当該パケットが再送されると、制御部３０８は、バッファ３０３に対応するパケット配列が蓄積されている場合には、そこに挿入して再構成を行ってもよい。また、受信装置４から当該パケットの再送要求があったときに送信できるようにバッファ３０３に格納してもよい。 If it cannot be repaired (step 501: NO), in step 503, the packet retransmission request control unit 309 requests the transmitter 1 to retransmit the lost packet. When the packet is retransmitted, the control unit 308 may insert the packet arrangement corresponding to the buffer 303 into the packet 303 and perform reconfiguration. Further, it may be stored in the buffer 303 so that it can be transmitted when there is a retransmission request of the packet from the receiving device 4.
　本発明は、送信装置から複数の受信装置に映像音声ストリームをマルチキャスト配信するシステムおよびストリーム配信中継装置に適用可能である。 The present invention is applicable to a system and a stream distribution relay device that multicast video and audio streams from a transmission device to a plurality of reception devices.
１　送信装置
２　中継装置
３　中継装置（エッジノード）
４　受信装置
３０１　通信Ｉ／Ｆ部
３０２　ストリーム抽出部
３０３　バッファ
３０４　パケット複製部
３０５　パケットロス検出部
３０６　冗長パケット削除制御部
３０７　通信Ｉ／Ｆ部
３０８　制御部
３０９　パケット再送要求制御部 1 Transmitter 2 Relay Device 3 Relay Device (Edge Node)
4 receiving apparatus 301 communication I / F unit 302 stream extraction unit 303 buffer 304 packet duplication unit 305 packet loss detection unit 306 redundant packet deletion control unit 307 communication I / F unit 308 control unit 309 packet retransmission request control unit

Claims (12)

  1. 　冗長符号を付加して配信されたパケットストリームを中継して受信装置へ直接送信するストリーム配信中継装置であって、
    　受信したデータパケットの連続性を監視してパケット消失を検出するパケットロス検出手段と、
    　パケット消失が検出されたときに当該パケット消失の修復に必要な冗長符号を残し他の冗長符号を削除する制御手段と、
    　を有することを特徴とするストリーム配信中継装置。     A stream distribution relay device that relays a packet stream distributed by adding a redundant code and directly transmits the packet stream to a receiving device,
    A packet loss detection means for monitoring the continuity of received data packets and detecting packet loss;
    Control means for leaving a redundant code necessary for repairing the packet loss when a packet loss is detected, and deleting other redundant codes;
    A stream distribution relay device comprising:
  2. 　前記制御手段は、前記パケットロス検出部でパケット消失を検出した場合に、当該パケット消失が修復可能か否かを判断し、修復できない場合には前記パケットストリームの送信元に対して消失パケットの再送要求を行うことを特徴とする請求項１に記載のストリーム配信中継装置。 When the packet loss detection unit detects packet loss, the control unit determines whether the packet loss can be repaired. If the packet loss cannot be repaired, the control unit resends the lost packet to the source of the packet stream. The stream delivery relay apparatus according to claim 1, wherein a request is made.
  3. 　前記冗長符号が前方誤り訂正（ＦＥＣ：Forward Error Correction）方式により付加されている場合、前記制御手段は、受信ストリームに含まれるＦＥＣパケットのうち、前記消失パケットを修復するために必要なＦＥＣパケットだけを選択し、その他のＦＥＣパケットを削除したパケットストリームを前記受信装置へ送信することを特徴とする請求項１または２に記載のストリーム配信中継装置。 When the redundant code is added by a forward error correction (FEC) method, the control means only requires FEC packets required to repair the lost packets among FEC packets included in the received stream. The stream delivery relay device according to claim 1, wherein a packet stream from which other FEC packets are deleted is transmitted to the receiving device.
  4. 　冗長符号を付加して配信されたパケットストリームを中継して受信装置へ直接送信する中継装置のストリーム配信制御方法であって、
    　受信したデータパケットの連続性を監視してパケット消失を検出し、
    　パケット消失が検出されたときに当該パケット消失の修復に必要な冗長符号を残し他の冗長符号を削除する、
    　ことを特徴とするストリーム配信制御方法。     A relay device stream distribution control method for relaying a packet stream distributed with a redundant code and directly transmitting the packet stream to a receiving device,
    Monitor the continuity of received data packets to detect packet loss,
    When a packet loss is detected, the redundant code necessary for repairing the packet loss is left and other redundant codes are deleted.
    A stream delivery control method characterized by the above.
  5. 　前記パケットロス検出部でパケット消失を検出した場合に、当該パケット消失が修復可能か否かを判断し、修復できない場合には前記パケットストリームの送信元に対して消失パケットの再送要求を行うことを特徴とする請求項４に記載のストリーム配信制御方法。 When packet loss is detected by the packet loss detection unit, it is determined whether or not the packet loss can be repaired. If the packet loss cannot be repaired, a retransmission request for the lost packet is made to the transmission source of the packet stream. The stream delivery control method according to claim 4, wherein:
  6. 　前記冗長符号が前方誤り訂正（ＦＥＣ：Forward Error Correction）方式により付加されている場合、受信ストリームに含まれるＦＥＣパケットのうち、前記消失パケットを修復するために必要なＦＥＣパケットだけを選択し、その他のＦＥＣパケットを削除したパケットストリームを前記受信装置へ送信することを特徴とする請求項４または５に記載のストリーム配信制御方法。 When the redundant code is added by the forward error correction (FEC: Forward Error Correction) method, only the FEC packet necessary for repairing the lost packet is selected from the FEC packets included in the received stream, and the others. 6. The stream distribution control method according to claim 4, wherein a packet stream from which the FEC packet is deleted is transmitted to the receiving device.
  7. 　冗長符号を付加して配信されたパケットストリームをネットワークを通して複数の受信装置へマルチキャスト配信するシステムであって、
    　前記ネットワーク内の複数の中継装置のうち、少なくとも１つの受信装置に直接接続された中継装置が、
    　　前記受信装置へ直接送信すべきデータパケットの連続性を監視してパケット消失を検出するパケットロス検出手段と、
    　　パケット消失が検出されたときに当該パケット消失の修復に必要な冗長符号を残し他の冗長符号を削除する制御手段と、
    　を有することを特徴とするストリーム配信システム。     A system for multicast distribution of a packet stream distributed with a redundant code to a plurality of receiving devices through a network,
    Among the plurality of relay devices in the network, a relay device directly connected to at least one receiving device,
    Packet loss detection means for detecting packet loss by monitoring continuity of data packets to be transmitted directly to the receiving device;
    Control means for leaving a redundant code necessary for repairing the packet loss when a packet loss is detected, and deleting other redundant codes;
    A stream distribution system comprising:
  8. 　前記制御手段は、前記パケットロス検出部でパケット消失を検出した場合に、当該パケット消失が修復可能か否かを判断し、修復できない場合には前記パケットストリームの送信元に対して消失パケットの再送要求を行うことを特徴とする請求項７に記載のストリーム配信システム。 When the packet loss detection unit detects packet loss, the control unit determines whether the packet loss can be repaired. If the packet loss cannot be repaired, the control unit resends the lost packet to the source of the packet stream. The stream delivery system according to claim 7, wherein a request is made.
  9. 　前記冗長符号が前方誤り訂正（ＦＥＣ：Forward Error Correction）方式により付加されている場合、前記制御手段は、受信ストリームに含まれるＦＥＣパケットのうち、前記消失パケットを修復するために必要なＦＥＣパケットだけを選択し、その他のＦＥＣパケットを削除したパケットストリームを前記受信装置へ送信することを特徴とする請求項７または８に記載のストリーム配信システム。 When the redundant code is added by a forward error correction (FEC) method, the control means only requires FEC packets required to repair the lost packets among FEC packets included in the received stream. The stream distribution system according to claim 7 or 8, wherein a packet stream from which other FEC packets are deleted is transmitted to the receiving device.
  10. 　冗長符号を付加して配信されたパケットストリームを中継して受信装置へ直接送信するストリーム配信中継装置としてプログラム制御プロセッサを機能させるコンピュータプログラムであって、
    　受信したデータパケットの連続性を監視してパケット消失を検出するパケットロス検出機能と、
    　パケット消失が検出されたときに当該パケット消失の修復に必要な冗長符号を残し他の冗長符号を削除する制御機能と、
    　を前記プログラム制御プロセッサに実現させることを特徴とするコンピュータプログラム。     A computer program that causes a program control processor to function as a stream distribution relay device that relays a packet stream distributed with a redundant code and transmits it directly to a receiving device,
    A packet loss detection function that monitors the continuity of received data packets and detects packet loss;
    A control function for leaving a redundant code necessary for repairing the packet loss and deleting other redundant codes when packet loss is detected;
    Is realized by the program control processor.
  11. 　前記制御機能は、前記パケットロス検出部でパケット消失を検出した場合に、当該パケット消失が修復可能か否かを判断し、修復できない場合には前記パケットストリームの送信元に対して消失パケットの再送要求を行うことを特徴とする請求項１０に記載のコンピュータプログラム。 When the packet loss is detected by the packet loss detection unit, the control function determines whether the packet loss can be repaired. If the packet loss cannot be repaired, the control function resends the lost packet to the transmission source of the packet stream. 11. The computer program according to claim 10, wherein the computer program makes a request.
  12. 　前記冗長符号が前方誤り訂正（ＦＥＣ：Forward Error Correction）方式により付加されている場合、前記制御機能は、受信ストリームに含まれるＦＥＣパケットのうち、前記消失パケットを修復するために必要なＦＥＣパケットだけを選択し、その他のＦＥＣパケットを削除したパケットストリームを前記受信装置へ送信することを特徴とする請求項１０または１１に記載のコンピュータプログラム。 When the redundant code is added by a forward error correction (FEC) method, the control function only requires FEC packets necessary for repairing the lost packet among FEC packets included in the received stream. The computer program according to claim 10 or 11, wherein a packet stream from which other FEC packets are deleted is transmitted to the receiving device.
PCT/JP2010/001820 2009-03-30 2010-03-15 Relay apparatus and distribution control method of stream distribution system WO2010116616A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2011508204A JPWO2010116616A1 (en) 2009-03-30 2010-03-15 Relay device and delivery control method in stream delivery system

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2009081460 2009-03-30
JP2009-081460 2009-03-30

Publications (1)

Publication Number Publication Date
WO2010116616A1 true WO2010116616A1 (en) 2010-10-14

Family

ID=42935916

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2010/001820 WO2010116616A1 (en) 2009-03-30 2010-03-15 Relay apparatus and distribution control method of stream distribution system

Country Status (2)

Country Link
JP (1) JPWO2010116616A1 (en)
WO (1) WO2010116616A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5600774B1 (en) * 2013-06-06 2014-10-01 日本電信電話株式会社 Data transmission apparatus and method

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5881356A (en) * 1981-11-10 1983-05-16 Kokusai Denshin Denwa Co Ltd <Kdd> Error control system
JPH0410723A (en) * 1990-04-27 1992-01-14 Nippon Telegr & Teleph Corp <Ntt> Diversity communication system
JP2004274703A (en) * 2003-02-19 2004-09-30 Intec Netcore Inc Router device and packet transfer control method

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5881356A (en) * 1981-11-10 1983-05-16 Kokusai Denshin Denwa Co Ltd <Kdd> Error control system
JPH0410723A (en) * 1990-04-27 1992-01-14 Nippon Telegr & Teleph Corp <Ntt> Diversity communication system
JP2004274703A (en) * 2003-02-19 2004-09-30 Intec Netcore Inc Router device and packet transfer control method

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5600774B1 (en) * 2013-06-06 2014-10-01 日本電信電話株式会社 Data transmission apparatus and method

Also Published As

Publication number Publication date
JPWO2010116616A1 (en) 2012-10-18

Similar Documents

Publication Publication Date Title
EP2039096B1 (en) Transmitting additional forward error correction (fec) upon request
US7725797B2 (en) Buffer for storing data and forward error correction (FEC)
US7899046B2 (en) Determining strategy for multicast and/or unicast transmission to correct forward errors
US7774672B2 (en) Requesting additional forward error correction
JP4405875B2 (en) Method and apparatus for generating data for error correction, generation program, and computer-readable recording medium storing the program
US8711854B2 (en) Monitoring and correcting upstream packet loss
JP5533322B2 (en) Data transfer device, data transfer method, and data transfer program
US10484148B2 (en) Method and device for transmitting and receiving multimedia data
US10833710B2 (en) Bandwidth efficient FEC scheme supporting uneven levels of protection
WO2010116616A1 (en) Relay apparatus and distribution control method of stream distribution system
JP2005065100A (en) Data distribution method, repeating system, and computer program
JP5592235B2 (en) Multicast pre-delivery method, system, and apparatus
JP4943188B2 (en) Multicast delivery apparatus, multicast delivery program, and recording medium
JP2006174298A (en) Data distribution method, relay apparatus, computer program and recording medium recording computer program
JP2008263489A (en) Multicast distributor, and multicast receiver
Chang et al. Accelerating Transmission of Streaming Files Based on AL-FEC Protection Blocks
JP2008005030A (en) Packet transmitter and receiver
WO2013015193A1 (en) Content delivery device, reception device, relay device, content delivery system, content delivery method and program
Lee et al. System and method for error-control for multicast video distribution
JP2006174299A (en) Data distribution method, receiver, computer program and recording medium recording computer program
Kang et al. An improved MORE protocol for satellite network based on network coding

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 10761324

Country of ref document: EP

Kind code of ref document: A1

WWE Wipo information: entry into national phase

Ref document number: 2011508204

Country of ref document: JP

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 10761324

Country of ref document: EP

Kind code of ref document: A1