KR20080022817A - Apparatus and method for retransmission of broadcast data in IP broadcast system - Google Patents

Abstract

An apparatus and a method for retransmitting broadcasting data in an IP(Internet Protocol) TV broadcasting system are provided to offer the broadcasting data to a set-top box in a unicast method in an area distribution data providing device, and transmit the broadcasting data at a reference transmission rate after transmitting the broadcasting data at an initial transmission rate during a certain time. A plurality of buffers(310-1~310-n) is provided to correspond to each channel received from an Internet subscriber connection device for providing broadcasting data in a multicasting method and has capacity in which broadcasting data corresponding to each channel is stored at a predetermined amount. A PSI(Program Specific Information) management unit(320) manages PSI including a PAT(Program Association Table) and a PMT(Program Map Table) which a provider which a provider supplying the broadcasting data sets up. A first connection management unit(330) performs communication by the Internet subscriber connection device and an IGMP(Internet Group Management Protocol) and receives broadcasting data on plural channels selected out of channels which a DSLAM(Digital Subscriber Line Access Multiplexer) supplies. A packet generation unit(350) generates a RTP(Real time Transport Protocol) packet including the PSI and a RTP packet including TSs(Transport Streams). A second connection management unit(340) sets a RTSP(Real-Time Streaming Protocol) session for data transceiving, receives the retransmission request information of a packet from a set-top box, and streams the RTP packets to the set-top box in a unicast method. A retransmission unit(360) instructs the packet generation unit to generate a RTP packet comprised of TSs corresponding to a RTP packet to be retransmitted, and provides the RTP packet to be retransmitted to the set-top box which requests retransmission through the second connection management unit.

Description

Apparatus and method for retransmitting broadcasted data in IP-TV broadcasting system}

1 is a view showing the configuration of the entire IP broadcast network to which the apparatus for retransmitting broadcast data according to the present invention;

2A and 2B are diagrams showing the configuration of the MPEG2-TS PSI and the configuration of the MPEG2-TS stream, respectively, and

3 is a diagram illustrating a detailed configuration of a preferred embodiment of an apparatus for retransmitting broadcast data in an IP broadcasting system according to the present invention.

The present invention relates to an apparatus and method for retransmitting broadcast data in an IP broadcast system, and more particularly, to a phenomenon in which a broadcast image received by another subscriber device is degraded by an operation of a subscriber device in an IP broadcast system. An apparatus and method for retransmitting broadcast data for preventing the same.

In recent years, the rapid spread of high-speed Internet and the development of information and communication technology have made the IP-TV service, which provides interactive TV service using the Internet, unlike the existing method of communication and broadcasting. It is being activated. IPTV is connected to a set-top box that processes IP video signals and converts them into standard TV signals. Using a switched video service (SVS) system, IPTV can be used for services such as broadband network channels, subscriber services, and movie watching. Can be connected selectively. This IP broadcasting system uses a telephone line which is laid up to each subscriber's home as a transmission path of broadcast data. At this time, the telephone line coming into the home of each subscriber is branched from the line bundle where the telephone lines corresponding to the subscribers in the same area are bound.

This line laying method has no problems with the voice call, a traditional service provided through a telephone line. However, when providing an IP broadcasting service, the operation of another subscriber device is affected by the operation of one subscriber device branched from the same line bundle. You can get For example, a surge occurs when a second subscriber who diverges from the line bundle to which the first subscriber's telephone line is watching IP turns on his set-top box, and instantly connects to the telephone line corresponding to the first subscriber. Noise may enter. In this case, part of the broadcast data provided to the first subscriber is lost, and the first subscriber views the deteriorated or disconnected video.

An object of the present invention is to provide an apparatus and method for retransmitting broadcast data for preventing interference between subscriber devices in an IP broadcast system.

Another object of the present invention is to provide a computer-readable recording medium having recorded thereon a program for executing a retransmission method of broadcast data for preventing interference between subscriber devices in an IP broadcast system.

The apparatus for retransmitting broadcast data for preventing interference between subscriber apparatuses in the IP broadcasting system according to the present invention is provided corresponding to each channel received from an internet subscriber access apparatus for providing broadcast data in a multicasting manner. A plurality of buffers having a capacity for storing broadcast data corresponding to a channel of a predetermined amount of time; A PSI manager configured to manage program specific information including a program association table and a program map table set by a provider for supplying the broadcast data; A first access management unit communicating with the Internet subscriber access device through an Internet Group Management Protocol to receive broadcast data for a plurality of channels selected from channels provided by the digital subscriber line access multiplexing device; A RTP packet including the program designation information provided from the PSI management unit is newly connected to the I-frame from a buffer corresponding to the requested channel from the set-top box requesting to provide broadcast data or requesting a channel change. A packet generator configured to generate an RTP packet including transport streams sequentially read from a corresponding transport stream; Set up an RTSP session for data transmission and reception with the connected set-top box, receive packet retransmission request information from the set-top box through the set RTSP session, and transmit the RTP packets generated by the packet generator. A second connection management unit streaming to the set top box by a cast method; When the retransmission request for the lost RTP packet is received from the set-top box, the packet generation unit is instructed to generate an RTP packet including a TS corresponding to the RTP packet to be retransmitted, and the RTP packet to be retransmitted generated by the packet generation unit. Retransmission unit for providing a set-top box requesting retransmission through the second connection; And a RTP packet corresponding to a channel requested by the set-top box for a predetermined period of time to a set-top box requesting broadcast data corresponding to a specific channel or requesting a channel change to be newly connected and having a higher transmission rate than a preset RTP packet transmission rate. And a control unit for transmitting at the initial transmission rate and controlling the transmission at the reference transmission rate when the predetermined time elapses.

As a result, it is possible to minimize the influence of interference between subscriber devices in the IP broadcasting system.

Hereinafter, a preferred embodiment of an apparatus and method for retransmitting broadcast data for preventing interference between subscriber devices in an IP broadcasting system according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a diagram illustrating a configuration of an entire broadcasting network to which an apparatus for retransmitting broadcast data is applied in an IP broadcasting system according to the present invention.

Referring to FIG. 1, the entire broadcasting network includes a set top box 110-1 to 110-n, a regional distributed data providing device 120, an internet subscriber accessing device 130, and a data providing server 140.

The set top boxes 110-1 to 110-n process user input commands such as a service request command and a channel change command input from a user, and generate a web packet corresponding to the user input command to connect to the public network. The server transmits to a server such as a mail server or generates a Real Time Streaming Protocol (RTSP) message and transmits it to the local distributed data providing apparatus 120. Here, the public network means a public telephone network, a wired / wireless internet network, a wireless communication network, and the like. Also, the set-top boxes 110-1 to 110-n decode broadcast data received from the regional distributed data providing device 120 and output the decoded broadcast data through the connected output device or the web device received from the public network. Output through The set top boxes 110-1 to 110-n and the local distributed data providing apparatus 120 transmit and receive data in a Real time Transport Protocol (RTP) packet.

In particular, in connection with the interference prevention, the set-top boxes (110-1 to 110-n) is the presence of the RTP packet received from the local distributed data providing apparatus 120 and lost from the broadcast data stored in the jitter buffer provided therein Find out. If there is a lost RTP packet in the broadcast data stored in the jitter buffer, the set-top boxes 110-1 through 110-n request retransmission of the corresponding RTP packet to the local distributed data providing apparatus 120. In this case, the set top boxes 110-1 to 110-n have a loss packet for the next area of the memory area in which the minimum broadcast data necessary for decoding is stored among the broadcast data stored in the jitter butter. Find out. In addition, the set-top boxes 110-1 to 110-n provide local distributed data providing apparatus 120 when the capacity of the jitter buffer provided therein becomes less than a certain level (for example, 10%) or when the jitter buffer becomes full. Send information about buffer capacity.

In addition, the set-top boxes 110-1 to 110-n establish a new RTSP session with the local distributed data providing apparatus 120 when a channel change command is input from the user, and localize information on the changed channel through the set RTSP session. It transmits to the distributed data providing apparatus 120. Next, the set top boxes 110-1 to 110-n decode broadcast data streamed from the regional data distribution apparatus 120 and output the decoded broadcast data through an output device. Here, the broadcast data received by the set-top boxes 110-1 to 110-n requesting the channel change from the regional distributed data providing apparatus 120 are discontinuous information (DI), PSI, and MPEG streams. In this case, the DI is information for determining whether the set-top boxes 110-1 to 110-n are broadcast data corresponding to the existing channel or the change channel, which are received from the local distributed data providing apparatus 120. If DI is '1', the set-top boxes 110-1 to 110-n interpret the received RTP or UDP packets as broadcast data corresponding to the changed channel, and if set to 0, broadcast data corresponding to the existing channel. Interpret with The DI is recorded in a TS located before the TS corresponding to the PSI in the RTP or UDP packet including the PSI or transmitted before the RTP or UDP packet corresponding to the PSI in an RTP or UDP packet separate from the PSI. In order to decode the received broadcast data, the set-top boxes 110-1 through 110-n must receive a transport stream (TS) packet corresponding to a PSI and an I-frame. 2A and 2B show the structure of the MPEG2-TS PSI and the structure of the MPEG2-TS stream, respectively.

The geographically distributed data providing apparatus 120 provides the broadcast data corresponding to the channel requested from the set-top box located in the lower part as an RTP packet by a unicast method. The geographically distributed data providing apparatus 120 may be provided in the Internet subscriber access device 130 or correspond to the Internet subscriber access device 130 as a separate device. The detailed configuration and operation of the geographically distributed data providing apparatus 120 will be described later.

The Internet subscriber access device 130 is located between the set-top boxes 110-1 to 110-n, which are subscriber terminal devices, and the public network to operate as an access node. An example of the Internet subscriber access device 130 may be a digital subscriber line access multiplexer (DSLAM). Hereinafter, a case where the Internet subscriber access device 130 is a DSALM will be described as an example. The DSLAM 130 streams the broadcast data to the regionally distributed data providing apparatus 120 located below in a multicast manner. At this time, the DSLAM 130 and the regional distributed data providing device 120 communicates by IGMP.

The data providing server 140 is located in the public network and provides the broadcasting data received from the data streamer of the broadcasting data provider to the DSLAM 130 located below in a multicasting manner. Although one data providing server 140 is shown in FIG. 1 for convenience, a plurality of such data providing servers 140 are located on a public network. In addition, although only one DSLAM 130 is shown below the data providing server 140, a plurality of DSLAMs may be connected to the lower part of the data providing server 140, and furthermore, an L2 switch and an optical communication line terminal. Terminal: OLT) etc. can be connected.

3 is a diagram illustrating a detailed configuration of a preferred embodiment of the apparatus 120 for providing geographical data according to the present invention.

Referring to FIG. 3, the apparatus 120 for providing geographical data according to the present invention includes a plurality of buffers 310-1 to 310-n corresponding to each channel, a PSI manager 320, and a first connection manager 330. ), A second connection manager 340, a packet generator 350, a retransmitter 360, and a controller 370.

In each buffer 310-1 to 310-n, broadcast data corresponding to each channel received from the DSLAM 130 is stored. Each of the buffers 310-1 to 310-n is a circular buffer in which newly received data is recorded in a place where the first received data is stored when the buffer capacity is full, and at least 5 seconds of broadcast data can be stored. Has storage capacity. Each of the buffers 310-1 to 310-n stores TSs constituting broadcast data (ie, MPEG streams) received from the DSLAM 130.

The PSI management unit 320 manages the PSI set by the broadcast data provider. The PSI includes a program association table (PAT), a program map table (PMT), a conditional access table (CAT), a network information table (NIT), a transport stream description table (TSDT), and the like. PAT is information table for PID of PMT or NIT corresponding to each channel, PMT is information table for PID list of data included in a specific channel, CAT is information table for stream management information, scrambling key, etc. to be. In addition, NIT and TSDT are information tables for networks and channels, respectively. The PSI management unit 320 holds the PSI set by the broadcast data provider in its own storage means, and provides the PSI held by the packet generation unit 350 in response to a PSI providing command input from the control unit 370. do. At this time, the PSI management unit 320 may provide only the PAT and PMT necessary for decoding the MPEG stream to the packet generation unit 350 among the PSI. Meanwhile, the PSI management unit 320 may extract the PSI from the broadcast data corresponding to each channel received from the DSLAM 130 and store the PSI in a storage unit provided therein. In this case, the PSI management unit 320 may be provided by the broadcast data provider. In order to prepare for the change of the PSI, it is preferable to update the PSI stored in the storage means with the PSI extracted from the most recently received broadcast data. The PSI management unit 320 may be integrated in the packet generation unit 350 to be described later.

The first access manager 330 communicates with the DSLAM 130 by IGMP to receive broadcast data for all channels from the DSLAM 130. To this end, the first access manager 330 transmits an IGMP message requesting transmission of broadcast data for all channels provided by the DSLAM 130 to the DSLAM 130. The message exchange between the first access management unit 330 and the DSLAM 130 and the streaming of the broadcast data is performed for all channels, except that the message exchange between the conventional set-top box and the DSLAM and streaming of the broadcast data Same as the process.

The second connection manager 340 provides a connection means between the geographically distributed data providing apparatus 120 and the set top boxes 110-1 to 110-n. To this end, the second connection manager 340 is provided with an RTSP module. In connection with the channel change, the second access manager 340 broadcasts data corresponding to the changed channel generated by the packet generator 350 through the set-top box 110-1 requesting the channel change and the RTSP session set up for the changed channel. Streaming the RTP packet containing the set-top box (110-1 to 110-n) requesting the channel change in a unicast manner. At this time, the second access manager 340 newly transmits the set-top boxes 110-1 to 110-n requesting broadcast data corresponding to a specific channel or requesting a channel change, and thus a transmission rate necessary for smooth decoding of broadcast data (hereinafter, referred to as a second channel). , Transmits an RTP packet corresponding to a channel requested by a corresponding set-top box (110-1 to 110-n) for a predetermined time at a higher transmission rate (hereinafter referred to as an 'initial transmission rate'). (Hereinafter referred to as 'initial transmission state'), and when a certain time elapses, the RTP packet is transmitted at the reference transmission rate (hereinafter referred to as 'reference transmission state').

The reference transmission rate is set to 4 Mbps when the broadcast data is encoded in MPEG2, and is set to 2 Mbps when encoded in MPEG4. In addition, the initial transmission rate is the time required for detecting whether or not the loss of the RTP packet stored in the jitter buffer of each set-top box (110-1 to 110-n) in the reference transmission rate and the set-top box (110) -1 to 110-n plus a time required from the time point at which the set-top boxes 110-1 to 110-n receive the RTP packet from the local distributed data providing apparatus 120 to request retransmission. It is set larger. Therefore, each set-top box (110-1 to 110-n) and the time required to detect whether the loss of the RTP packet stored in the jitter buffer provided in the set-top box (110-1 to 110-n) If the sum of the time required from the time point at which the request for retransmission is received by the set-top boxes 110-1 to 110-n to the time point for receiving the RTP packet from the local distributed data providing apparatus 120 is 0.5 seconds, the MPEG The initial transmission rate for broadcast data encoded with 2 is set to at least 6Mbps.

This initial transmission state is provided from the set-top boxes (110-1 to 110-n) the buffer capacity information indicating that the free capacity of the jitter buffer provided therein is less than a certain level (for example, 10%) or that the jitter buffer is full. It lasts until it is received. In contrast, the initial transmission state is broadcast data stored in the buffers 310-1 to 310-n at the start of RTP packet transmission to the set-top boxes 110-1 to 110-n (for example, 5 buffers). If it is a second buffer and broadcast data is encoded in MPEG2, it can be continued until all 20M broadcast data) is transmitted. The duration of the initial transmission state is variably set according to the encoding method of the broadcast data and the bandwidth of the line allocated to the set top boxes 110-1 to 110-n.

The packet generator 350 streams the TS from the buffers 310-1 to 310-n corresponding to the changed channel to the set-top box 110-1 requesting a channel change in response to a control command of the controller 370. Create an RTP packet to be used. For example, when a channel change request of channel 2 is received from the set-top box 110-1 receiving stream data corresponding to channel 1, the packet generator 350 first transmits a subsequent RTP or UDP packet. It generates an RTP or UDP packet including DI for indicating whether the broadcast data corresponding to the channel or the broadcast data corresponding to the changed channel. Next, the packet generation unit 350 generates an RTP or UDP packet including the PSI provided from the PSI management unit 320. In this case, the packet generator 350 may generate DI and PSI as one packet. Subsequently, the packet generator 350 sequentially reads the TSs from the TSs corresponding to the I-frames from the buffer 310-2 corresponding to the channel 2 to generate an RTP packet. In this case, each of the buffers 310-1 to 310-n has a buffer capacity (eg, a capacity capable of storing a TS of 5 seconds) longer than the transmission interval (eg, 0.5 seconds) of the I-frame. As a result, a plurality of I-frames may be stored in the buffer 310-2 corresponding to the channel 2. Accordingly, the packet generator 350 may generate one I-frame (for example, the second received I) among a plurality of I-frames stored in the buffer 310-2 corresponding to the channel 2 according to the setting state of the device. Frame) to sequentially read the TSs from the corresponding TSs to generate an RTP packet. The RTP packet generated in this manner is streamed to the set-top box 110-1 by which the channel change request is sequentially performed by the second access manager 340. 4 illustrates a broadcast data streaming procedure between a buffer provided in the apparatus 120 for providing local distributed data and a set-top box requesting a channel change.

The retransmission unit 360 retransmits the RTP packet corresponding to the sequence requested by the set top boxes 110-1 through 110-n to the set top boxes 110-1 through 110-n requesting retransmission. To this end, the retransmission unit 360 identifies the RTP packet to be retransmitted, and instructs the packet generation unit 350 to generate an RTP packet including a TS corresponding to the RTP packet. In addition, the retransmitter 360 transmits the RTP packet to be retransmitted generated by the packet generator 350 to the set top boxes 110-1 to 110-n requesting retransmission through the second access unit 340.

The controller 370 controls the operation of each module constituting the regional distributed data providing device 120. In particular, in relation to packet retransmission, the control unit 370 is fixed to the set-top boxes 110-1 to 110-n that the second connection unit 340 newly accesses to request broadcast data corresponding to a specific channel or requests for channel change. During the time, the set-top boxes (110-1 to 110-n) transmits the RTP packet corresponding to the requested channel at the initial transmission rate, and then controls to transmit at the reference transmission rate. In addition, the controller 370 analyzes the RTSP packets received from the set-top boxes 110-1 to 110-n to identify the RTP packets to be retransmitted, and performs the retransmission procedure for the corresponding RTP packets to the retransmission unit 360. Outputs a control command.

Meanwhile, the controller 370 analyzes the RTSP packet received from the set top box 110-1 requesting the channel change in relation to the channel change, and the IP address of the set top box 110-1 requesting the channel change, and the corresponding set top box ( A channel of broadcast data provided to 110-1) and a change channel requested by the corresponding set-top box 110-1 are identified. In addition, the control unit 370 instructs the PSI management unit 320 to provide the PSI to the packet generation unit 350, and provides the packet generation unit 350 with information on the identified change channel to request the channel change. Instructs generation of an RTP packet to stream to box 110-1. In addition, the controller 370 outputs a control command to the second connection manager 340 to stream the RTP packet generated by the packet generator 350 to the set-top box 110-1 requesting the channel change.

The invention can also be embodied as computer readable code on a computer readable recording medium. The computer-readable recording medium includes all kinds of recording devices in which data that can be read by a computer system is stored. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage, and the like, and may also be implemented in the form of a carrier wave (for example, transmission over the Internet). Include. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion.

Although the preferred embodiments of the present invention have been shown and described above, the present invention is not limited to the specific preferred embodiments described above, and the present invention belongs to the present invention without departing from the gist of the present invention as claimed in the claims. Various modifications can be made by those skilled in the art, and such changes are within the scope of the claims.

According to the apparatus and method for retransmitting broadcast data in the IP broadcasting system according to the present invention, the apparatus for providing local distributed data provides broadcast data to the set-top box in a unicast manner, and initially transmits the broadcast data for a predetermined time to the set-top box. Since the packet is lost by the operation of another subscriber connected to the telephone line branched from the common line bundle, the packet is lost without affecting the decoding process of the broadcast data. Packets can be recovered.

Claims (1)

A plurality of buffers provided corresponding to respective channels received from an Internet subscriber access apparatus for providing broadcast data in a multicasting manner, the plurality of buffers having a capacity for storing a predetermined amount of broadcast data corresponding to each channel; A PSI manager configured to manage program specific information including a program association table and a program map table set by a provider for supplying the broadcast data; A first access management unit communicating with the Internet subscriber access device through an Internet Group Management Protocol to receive broadcast data for a plurality of channels selected from channels provided by the digital subscriber line access multiplexing device; A RTP packet including the program designation information provided from the PSI management unit is newly connected to the I-frame from a buffer corresponding to the requested channel from the set-top box requesting to provide broadcast data or requesting a channel change. A packet generator configured to generate an RTP packet including transport streams sequentially read from a corresponding transport stream; Set up an RTSP session for data transmission and reception with the connected set-top box, receive retransmission request information from the set-top box through the set RTSP session, and transmit the RTP packets generated by the packet generator. A second connection management unit streaming to the set top box by a cast method; When the retransmission request for the lost RTP packet is received from the set-top box, the packet generation unit is instructed to generate an RTP packet including a TS corresponding to the RTP packet to be retransmitted, and the RTP packet to be retransmitted generated by the packet generation unit. Retransmission unit for providing a set-top box requesting retransmission through the second connection; And The RTP packet corresponding to the channel requested by the set-top box for a predetermined time is initially set higher than the reference transmission rate, which is a transmission rate of a preset RTP packet, to the set-top box requesting broadcast data corresponding to a specific channel or requesting channel change. And a control unit which transmits at the transmission rate and controls the transmission at the reference transmission rate when the predetermined time elapses.

Images