KR20110070440A - Ip based multicast video service changing method with docsis service information table - Google Patents

Abstract

PURPOSE: A channel changing method of an IP-based multicast video service using a DOCSIS service information table is provided to efficiently offer a service flow for a converted program. CONSTITUTION: A cable modem receives DOCSIS(Data Over Cable Service Interface Specification) service information from a head end(S501). According to whether to change a DOCSIS service information table, the cable modem modifies the DOCSIS service information table(S502,S503). According to a changed channel bonding group, the cable modem modifies the DOCSIS service information table(S506). The cable modem modifies downstream service ID filtering information(S507).

Description

Channel change method of IP-based multicast video service using DOCSIIS service information table {IP BASED MULTICAST VIDEO SERVICE CHANGING METHOD WITH DOCSIS SERVICE INFORMATION TABLE}

The present invention relates to a method for controlling transmission of digital cable broadcasting, and more particularly, to a method for efficiently switching IP-based multicast video services in an HFC-based cable network.

The present invention is derived from the research conducted as part of the IT growth engine technology development of the Korea Communications Commission. [Task Management Number: 2008-S-005-02, Title: Development of IP-based High-Speed Multimedia Transmission Technology in HFC Networks] ]

In a hybrid fiber coax (HFC) network, a digital video broadcasting service transmits a compression coded digital video data stream to a user through a quadrature amplitude modulation (QAM) channel.

Switched Digital Video (SDV) service refers to a digital video transmission service that includes not only real-time broadcast video service but also video service on demand such as Video on Demand (VoD). SDV improves the efficiency of the frequency channel band by selectively transmitting the required program channels from subscribers of the same service group. Existing digital broadcasting service transmits all program channels to all viewers in the same group through QAM channel regardless of subscriber's viewing. On the other hand, the SDV transmission method is more efficient than the conventional digital broadcasting service method because it transmits only the program channels requested from the viewers in the same service group through the QAM channel and does not transmit the program channels not requested by the viewers. Can be used as

1 is a diagram schematically illustrating an IP-based video transmission structure. FIG. 1 exemplarily illustrates a case where the DOCSIS protocol is applied as a protocol for IP-based video transmission.

Referring to FIG. 1, the IP-based video transmission structure includes an IP-set top box (hereinafter referred to as IP-STB) 101 at the subscriber side to identify each subscriber by an IP address, and to identify a subscriber-directed multicast session. Form. IP-based video transmission architecture can increase the flexibility of the service by introducing a multicast-type video transmission scheme to the cable network. In the multicast video transmission method, a video program requested by a subscriber is transmitted only to the corresponding subscriber or a group of subscribers (reference numeral 102), and the video stream does not flow into the subscriber who does not request the service.

IP-based multicast video transmission service can apply a transmission method based on DOCSIS 3.0 specification to deliver IP data in the HFC cable network section. DOCSIS is a European and North American standard that describes the transport characteristics and procedures of the physical and link layers to provide data packet-based services over cable networks.

For the IP-based video transmission service shown in FIG. 1, DOCSIS-QAM having a Modular-Cable Modem Termination System (M-CMTS) device 103, which is a DOCSIS packet processing device, and a frequency signal modulation function conforming to the DOCSIS standard. (D-QAM) channel transmission device 104 is provided. At the subscriber side, an IP-STB 101 is used that can process IP addresses and data streams. In addition, a cable modem (CM) 105 for demodulating and decoding an RF signal and a DOCSIS packet processing provided to a subscriber for IP packet transmission in a cable network section is provided.

In the IP-based video transmission service structure, the video data stream 106 is introduced from the video server to the head end of the cable network through the IP network according to the User Datagram Protocol (UDP) / Real-time Transport Protocol (RTP) protocol. The incoming video data stream 106 is divided and scheduled in the form of a multicast or unicast service flow for DOCSIS transmission by the M-CMTS 103 located at the headend. The M-CMTS 103 adds the header of the DOCSIS MAC layer to the scheduled result and delivers it to the subscriber's DOCSIS cable modem 105. The DOCSIS cable modem 105 receives a service flow data packet corresponding to its service ID according to a Downstream Service ID (DSID) according to the service flow. DOCSIS cable modem 105 buffers and realigns the received data. The rearranged data is transmitted to the corresponding IP STB 101.

However, since the above-described SDV method transmits only the program that the subscriber is currently watching, the program transmission starts with the request of the subscriber. According to such a configuration, in the SDV method, when a program is started / changed by a subscriber with respect to a real-time transmission program, the response speed thereof is slower than that of the conventional method. For example, due to a process of transmitting and receiving a management message on the DOCSIS MAC layer between the cable modem and the headend cable modem according to a program channel change request from the subscriber, a service flow reception overhead is large. Therefore, in order to provide a real-time broadcasting service through the SDV method, an efficient countermeasure for improving the response speed according to the conversion of the IP-based multicast video service is required.

Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide a method for efficiently converting an IP-based multicast video service in an HFC-based cable network.

Another object of the present invention is to provide a method for efficiently receiving a service flow for a switched program in a cable modem.

Another object of the present invention is to provide a DOCSIS cable modem as a subscriber device, a DOCSIS service information table control method between an IP-STB and a head-end cable modem, a DOCSIS service information table operating method of a DOCSIS cable modem, and a video service flow related thereto. The present invention provides a method and procedure for controlling a cable modem device.

In order to achieve the above object, a method of changing a channel of an IP-based multicast video service according to an embodiment of the present invention includes: receiving, by a cable modem, data over cable service interface specification (DOCSIS) service information from a headend, and changing a DOCSIS service information table. Checking, changing the DOCSIS service information table according to whether the DOCSIS service information table is changed, and waiting for a next service information message to be received, wherein the cable modem notifies a change of a downlink bonding group from the headend; Modifying the DOCSIS service information table according to the changed channel bonding group, modifying downlink service identifier filtering information so as to correspond to the modified DOCSIS service information table, and wherein the filtering information is a modified downlink service identifier. Stri Receiving a rim, if the cable modem receives a multicast session service change message from a video client, determining whether the received message is session setting information or session deletion information, and receiving the received message according to the determination result. Modifying the downlink service identifier filtering information to correspond to the received message, and receiving a stream with the downlink service identifier with the filtering information modified to correspond to the received message.

According to the present invention as described above, when the subscriber device in the cable network to receive the IP-based multicast video service, by periodically receiving the DOCSIS service information table to minimize the channel change response time according to the program channel change request from the subscriber side You can do it.

In addition, it is possible to omit the process of transmitting and receiving a management message on the DOCSIS MAC layer, which is performed when the conventional program channel is changed, so that the program can be switched more efficiently and the service flow for the switched program can be efficiently received. .

In addition, the cable for receiving DOCSIS service information table between the subscriber device DOCSIS cable modem, IP-STB and headend cable modem, operating DOCSIS service information table of DOCSIS cable modem, and receiving the related video service flow in IP-based video transmission service. The operation of the modem device can be efficiently controlled.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art may easily implement the technical idea of the present invention. Identical components will be referred to using the same reference numerals. And like elements will be quoted using like reference numerals. The following embodiments may be modified in various forms, and the scope of the present invention is not limited to the embodiments described below.

The present invention relates to an efficient switching method of an IP-based multicast video service using a DOCSIS service information table in an HFC-based cable network, and provides a control method for applying to a subscriber device of a cable network. The present invention can minimize the channel change response time according to the program channel change request from the subscriber side by periodically receiving the DOCSIS service information table when the subscriber device wants to receive the IP-based multicast video service in the cable network. According to such a configuration, since a process of exchanging a management message on a DOCSIS MAC layer according to a conventional program channel change can be omitted, a program can be switched more efficiently, and a service flow for the switched program can be efficiently Can be received.

2 is a diagram exemplarily illustrating a configuration of an IP-based multicast video transmission system according to the present invention using a DOCSIS service information table.

Referring to FIG. 2, the headend 209 and the video transmission control device 202 are IP-based video stream processing and control devices for providing a switched digital video service, and the service flow may be transmitted only to a limited service group. It is in charge of handling and controlling functions. The session management server 203 of the video transmission control device 202 sets up an IP multicast session to be delivered to the subscriber when the video service program request information is received from the subscriber, and delivers information about the multicast session to be serviced to the video client. (See reference numeral 210). The resource manager 204 included in the video transmission control device 202 manages frequency channel resources including bandwidth, QoS information, and IP group address required to provide a video program service requested from the session management server 203. A device that manages channel resources using Real Time Streaming Protocol (RTSP) (see reference numeral 211).

The DOCSIS layer configures transmission for each service flow for the multicast service flow. Therefore, the IP STB needs to repeat the transmission request / response process 216 through the MAC management message for the service flow each time the multicast video service is requested. However, this process can cause a long service response time. In order to prevent such a problem, in the present invention, the DOCSIS service information table (DOCSIS in the drawing) is provided through the M-CMTS so that information about DOCSIS service flows in the cable network can be shared by cable models (CM) belonging to the same service group. 213) to the cable modem.

M-CMTS 205 is provided at the head end 209 on the video plane through which video data is transmitted, so that a subscriber requesting an IP-type video service flow input through a WAN 212, which is an IP network. Performs a function of classifying / dividing a service flow so that it can be transmitted only to a group. The M-CMTS 205 processes the DOCSIS frame header by copying one or more packets according to the service group to be transmitted if necessary, and transmits the DOCSIS frame header to the multicast group formed according to the service group to be transmitted. Video service flows input over IP network 212 are sent to an Edge Quadrature Amplitude Modulation (EQAM) based device (denoted DOCSIS EQAM in the figure) 206. The EQAM based device 206 outputs the video service flow to the cable based subscriber device via an RF channel using the channel resources allocated by the resource manager 204 on the control plane. The headend 209 periodically outputs the DOCSIS service group information table 213 to the cable modem in order to be able to send a quick response when the video client makes a program request. The DOCSIS service group information table 213 may include multicast service flow identifier (SFID), multicast group MAC address information, multicast group IP address, multicast session information, and downlink service identifier (DSID) information. The content contained in the table is not limited to a particular type of information.

The DOCSIS cable modem 207 receives and processes the video data stream received through the HFC network. For example, DOCSIS cable modem 207 receives the incoming video data stream and processes the DOCSIS header to convert it to an IP-based MPEG2-TS video stream. The converted IP-based MPEG2-TS video stream is output to an IP set-top box (STB) for reproduction and processing of video data. In addition, the DOCSIS cable modem 207 operates a DOCSIS service information table 213 for receiving a video service flow, and performs reception or filtering (see reference numeral 215) for the multicast service flow. To this end, the DOCSIS cable modem 207 is configured to interwork with the IP multicast group address information for the program obtained by the video client 208, and is configured to acquire the multicast service flow processing information in advance.

The video client 208 restores and decodes the video data stream received from the IP-based video STB device into an MPEG-2 based video stream in the form of an IP packet and outputs the video data stream to the subscriber playback device. In addition, the video client 208 may transmit service request information such as a program channel change to the video session management device 203 to obtain program information and a multicast group address necessary for the corresponding program service (see reference numeral 210). In order to set up a cable network transmission, multicast session related information (see reference numeral 214) may be transmitted and received to the cable modem 207.

3 is a diagram illustrating a detailed configuration of an IP-based multicast video transmission system according to the present invention. 3 illustrates a subscriber device control structure using the DOCSIS service information table 213.

Referring to FIG. 3, the DOCSIS cable modem 207 includes a DOCSIS service group information table manager 303, a DOCSIS MAC protocol processor 304, a cable modem 305, and an SDV flow reception controller 306. do.

The cable modem 305 performs operations such as physical signal processing for the frequency channel received through the HFC cable network and reception on the DOCSIS-based MAC layer. The cable modem 305 processes the video data stream received in the form of DOCSIS multi-program transport streams (MPTS) into an IP-based MPEG2-TS video stream, and then sends the video data to the video client device 208 for playback and processing of the video data. (See ref. 312).

The DOCSIS service group information table manager 303 operates a DOCSIS service information table for receiving a video service flow and performs a reception or filtering process for the multicast service flow. To this end, the DOCSIS cable modem 207 is interworked with the IP multicast group address information for the program acquired by the video client device 208, and obtains the multicast service flow processing information from the video transmission control device 202 in advance. . The IP multicast group address information for the program may be provided to the SDV flow reception control unit 306 through the cable modem control unit 310 provided in the video client device 208.

For example, in the DOCSIS cable modem 207, the DOCSIS service group information table manager 303 acquires a downlink service identifier (DSID) capable of filtering the multicast service flow. The DOCSIS service group information table manager 303 selectively receives only data packets input through the acquired DSID and receives a multicast video service. Multicast service flows flowing through the HFC cable network share the same DSID in cable modem groups belonging to the same service group. If the DSID information of the multicast sessions already being serviced in the same service group is known in advance, the process of acquiring the information through the DOCSIS MAC protocol processing unit 304 may be omitted. Therefore, the service can be provided within a faster service response time.

In the present invention, the information on the multicast group addresses being serviced in the same service group is operated by the DOCSIS service group information table management unit 303 in the form of a table (see DOCSIS service group information table 213 in FIG. 2), and a video. Whenever there is a program request from the client device 208, the table is first searched for fast service switching. To this end, the DOCSIS cable modem 207 is configured to receive a multicast IP group address whenever a program request from the video client device 208 is received, and also to transmit DOCSIS service group information to the video transmission device 202 which is a control plane. It periodically receives the input from the DOCSIS service group information table management unit 303 to store and manage in the DOCSIS service group information table 312.

The video client device 208 includes a program request protocol processor 307, a program information table manager 308, an IP-based video STB device (denoted as IP STB in the drawing) 309, and a cable modem controller 310. . The video client device 208 restores and decodes the video data stream received in the form of an IP packet through the IP-based video STB device 309 into an MPEG-2 based video stream. The MPEG-2 based video stream reconstructed and decoded by the video client device 208 is output through the subscriber playback device 311.

The video client device 208 is a terminal device that performs a request and transmission setting for a video program based on IP. The video client device 208 operates in accordance with the IP multicast client protocol. The video client device 208 transmits service request information, such as a program channel change, to the video transmission control plane 202 through the program request protocol processor 307. The video client device 208 then obtains the program information and the multicast group address necessary for the requested program service through the program information table manager 308. The video client device 208 transmits the multicast session related information to the SDV flow reception control unit 306 of the DOCSIS cable modem 207 through the cable modem control unit 310 to establish transmission of the cable network section (reference number 313). Reference).

4 is a diagram exemplarily illustrating a device-to-device control protocol stack using a DOCSIS information table.

Referring to FIG. 4, the DOCSIS headend 209 and the cable modem 207 of the HFC cable network exchange DOCSIS SI Application 401 information by UDP socket 402 communication, and the service information is IP 403 and It is sent over the Ethernet 404 to the DOCSIS MAC layer 405 and DOCSIS physical layer (denoted as DOCSIS PHY Layer in the figure) 406.

For the local interface on the subscriber side, DOCSIS service information between DOCSIS cable modem 207 and video client 208 communicates at the application layer via UDP socket 409. In the video client 208, the video application information 407 is channel change protocol (CCP) encapsulation 408, and the L1 layer (represented as a Data Link Layer in the figure) via UDP 409 and IP 410 ( 411) / L2 layer (denoted as PHY Layer in the figure) 412.

5 is a diagram illustrating a control method according to the present invention for receiving an IP-based multicast video stream in a cable modem.

Referring to FIG. 5, the cable modem receives DOCSIS service information (DOCSIS SI) from the M-CMTS on the headend side (step S501) and checks whether the DOCSIS service information (SI) table has been changed (step S502). . If the DOCSIS service information (SI) table has been changed as a result of the check in step S502, the service information (SI) table is modified (step S503), and the DOCSIS service information message reception wait state is entered (step S504). If there is no change in the DOCSIS service information (SI) table as a result of the check in step S502, the procedure goes to step S504 to wait for the next service information message to be received.

When the cable modem receives the DBC (Dynamic Bonding Change) message informing of the downlink bonding group change from the M-CMTS (step S505), the cable modem modifies the DOCSIS service information (SI) table according to the changed channel bonding group (step S506). . Then, after modifying the downstream service identifier (DSID) filtering information to correspond to this (step S507), the stream is received with the changed DSID (step S508).

On the other hand, when the cable modem receives the multicast session service change message from the IP-STB of the video client side (step S509), it is determined whether the received information is session establishment information or session deletion information (step S510). As a result of the determination in step S510, if the received information is session setting information, the DSID filtering information is modified to correspond thereto (step S511), and the stream starts to be received with the modified DSID (step S508). At this time, the session configuration information includes an IP group address and a session ID. As a result of the determination in step S510, if the received information is session deletion information, the DSID filtering information is corrected to correspond thereto (step S512), and the stream is filtered by the DSID (step S513). At this time, the session deletion information includes an IP group address and a session ID.

6 is a diagram illustrating a channel changing method according to the present invention performed in an IP-STB device of a video client.

Referring to FIG. 6, when the IP-STB receives a channel change application programming interface (API) from the user (step S601), the IP-STB transmits multicast session deletion information on the changed channel to the cable modem (step S602). At this time, the session deletion information includes an IP group address and a session ID. The multicast session configuration information for the channel to be changed is transmitted to the cable modem (step S603). Session configuration information includes an IP group address and a session ID. After the session setup for the cable modem is complete, the channel change process of the control plane begins.

As described above, in the present invention, when a subscriber device receives an IP-based multicast video service in a cable network, the cable modem periodically receives a DOCSIS service information table, so that the channel change response time according to the program channel change request from the subscriber side. Can be minimized. That is, when the DOCSIS service information table according to the present invention is used, program information and IP multicast group information can be obtained without a separate MAC management message transmission and reception when a channel change request or a downlink channel group is changed from a video client. Therefore, the program change response time and the channel switching time can be minimized, and the service flow for the switched program can be more efficiently received.

As described above, embodiments of the present invention have been disclosed. Although specific terms have been used herein, they are used only for the purpose of describing the present invention and are not used to limit the scope of the present invention as defined in the meaning or claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible from this. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

1 is a diagram schematically illustrating an IP-based video transmission structure.

2 is a diagram exemplarily illustrating a configuration of an IP-based multicast video transmission system according to the present invention using a DOCSIS service information table.

3 is a diagram illustrating a detailed configuration of an IP-based multicast video transmission system according to the present invention.

4 is a diagram exemplarily illustrating a device-to-device control protocol stack using a DOCSIS information table.

5 is a diagram illustrating a control method according to the present invention for receiving an IP-based multicast video stream in a cable modem.

6 is a diagram illustrating a channel changing method according to the present invention performed in an IP-STB device of a video client.

* Description of the symbols for the main parts of the drawings *

202: video transmission control device 203: session management server

204 Resource Manager 205 M-CMTS

206: DOCSIS EQAM 207: DOCSIS Cable Modem

208: video client 209: headend

303: DOCSIS service group information table management unit

304: DOCSIS MAC protocol processing unit

305 cable modem

306: SDV flow receiving control unit

307: program request protocol processing unit

308: program information table management unit

309: IP based video STB device (IP STB)

310: cable modem control unit

Claims (1)

Receiving, by the cable modem, data over cable service interface specification (DOCSIS) service information from the headend; Checking whether the DOCSIS service information table has been changed; Changing the DOCSIS service information table according to whether the DOCSIS service information table is changed and waiting for a next service information message to be received; Modifying the DOCSIS service information table according to the changed channel bonding group when the cable modem receives a message informing of a downlink bonding group change from the headend; Modifying downlink service identifier filtering information to correspond to the modified DOCSIS service information table; Receiving a stream with a downlink service identifier modified with the filtering information; When the cable modem receives a multicast session service change message from a video client, determining whether the received message is session establishment information or session deletion information; Modifying the downlink service identifier filtering information to correspond to the received message according to the determination result; And And receiving a stream with a downlink service identifier with the filtering information modified to correspond to the received message.

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