KR100527203B1 - Opencable settop box of dsg mode and method for acquiring channel information - Google Patents

Abstract

The present invention relates to an apparatus and method for watching cable broadcasting in an open cable standard, wherein the set top box includes channel information through a cable network to which the DOCSIS scheme is applied so that the set top box performs MPEG filtering, which is a function of the cable card. Receive the received signal, obtain the DSG MAC tunnel address for the received signal, perform MPEG PID filtering, and assemble DSG data included in the received DSG packets to generate MPEG section data for searching a broadcast channel. Provide to the navigator. By allowing a viewer to watch a broadcast using only a set-top box without a cable card, it is possible to reduce the cost of having a separate cable card.

Description

Set-top box of DS mode with channel information acquisition function in open cable type cable broadcasting and channel information acquisition method using the same {OPENCABLE SETTOP BOX OF DSG MODE AND METHOD FOR ACQUIRING CHANNEL INFORMATION}

The present invention relates to a cable broadcast receiving apparatus and method of an open cable standard, and more particularly, to a cable broadcast receiving apparatus and method capable of receiving a broadcast without providing a separate cable card.

Currently, the channel bandwidth according to the US-based OPENABLE standard in CATV is 6 MHz, which is insufficient to simultaneously broadcast a large number of programs and channel information. Therefore, in the open cable method, channel information, CA (Conditional Access) information, and the like are separated from broadcast data and transmitted through a channel other than the broadcast channel. In the open cable method, channel information and CA information are transmitted through a cable network to which an out-of-band (OBB) or data-over-able service interface specifications (DOCSIS) method is applied.

The channel information (SI) that comes down through OOB band or DOCSIS is composed of various section tables. In this table, MGT (Master Guide Table) which maps Program IDentifier (PID) to other tables, Network Information Table (NIT) that shows channel characteristics such as frequency, and Short-form Virtual that shows channel number. Channel Tables, Long-form Virtual Channel Tables (LVCT), and Aggregate Event Information Table (AEIT) / Aggregate Extended Test Table (AETT) used in the Electronic Program Guide (EPG). See SCTE 65 for details on each of these tables.

Since SI, which is channel information, is received through an out-of-band channel rather than a broadcast channel, a viewer must perform a process of mapping broadcast data received through a broadcast channel and SI received through an out-of-band channel in order to normally view the broadcast. . This mapping process is called "Moving Picture Experts Group (MPEG) filtering".

The cable card (former name POD (Point Of Deployment)) performs the filtering of the OOB SI mentioned above, and the method of delivering the OOB SI to the cable card can be largely divided into the following two ways. First, there is a method of using a modem provided by a cable card, that is, an OOB mode, and second, a method of using a modem provided by a set-top box, that is, a DSG (DOCSIS System Gateway) mode.

In the OOB mode, data exchange such as control access program information between the headend and the set-top box is performed through an out-of-band channel other than the audio video channel.

DSG mode sends down SI information through DOCSIS-compatible cable modem used in existing Internet subscriber network. This method has a higher basic transmission bandwidth (10Mbps) than OOB mode using DVS-167 or DVS-178 (> = 2Mbps) (ie, the cable card delivers the SI directly). Switching to DOCSIS 2.0 is easy. In terms of service providers, DVS-167,178 requires additional headend equipment called Intersect. However, DSG method does not require additional expenses because the CMTS headend equipment used by the operator can be used as it is.

1 is a configuration diagram of a DSG mode in which SI is delivered to a set-top box through a cable network to which a DOCSIS scheme is applied.

In FIG. 1, the set-top network controller 100 is a device for transmitting an SI, and an SI generator or the like corresponds to the set-top network controller 100. The set top network controller 100 delivers the SI to each cable modem termination system (CMTS) 130 by IP multicast or unicast.

The CMTS 130 converts a packet including the SI received from the set-top network controller 100 into a DSG Tunnel Mac address whose destination is a well-known Media Access Control (MAC) address. After the translation, it is sprayed on the cable network to which DOCSIS is applied (generally, the cable network is a broadcast structure). Therefore, even if the set-top box (STB) 140 is mixed with a general cable modem, only the set-top box 140 capable of recognizing the DSG tunnel MAC address can process the packet. On the other hand, since the DSG tunnel MAC address is obtained by the cable card and provided to the set-top box 140, the cable card is required in addition to the set-top box 140 to watch the cable broadcast.

2 is a data flow diagram between the cable card and the set-top box in the DSG mode.

The cable card 200 is connected to the set-top box 140 and PCMCIA to configure the HOST-POD interface, and shows the data flow as shown in FIG. Referring to the DSG data flow of FIG. 2, the set top box 140 receives SI data transmitted from the CMTS 130 and transmits the SI data to the cable card 200. To describe this process in detail, a modem (eg, High Speed Host Modem) 212 in the set-top box 140 receives SI data from the CMTS 130 and performs an IP / Port routing processing unit of the set-top box 140 ( 214, and the IP / Port routing processor 214 of the set-top box 140 transmits it back to the IP / Port routing processor 214 of the cable card 200. The cable card 200 receives the DSG data and performs MPEG transport filtering / processing, etc. The resulting MPEG section tables are navigators 220 of the set-top box 140. To pass. In order for the navigator 220 of the set-top box 140 to operate and change channels, an MPEG section table provided by the cable card 200 is required.

On the other hand, the cable card 200 is a PCMCIA type device requires its own CPU, RAM, OS, etc., and is not part of the set-top box 140, the user must purchase separately. That is, in order to watch the broadcast desired by the user, the cable card 200 is required in addition to the set-top box 140, which causes an increase in overall cost.

On the other hand, unlike the OOB mode in which the modem of the cable card 200 is used to receive the SI, the modem of the cable card 200 is not used in the DSG mode. That is, if a set-top box 140 capable of filtering MPEG without using the cable card 200 in the DSG mode is provided, the viewer will be able to watch cable broadcasting without having a separate cable card 200.

An object of the present invention is to provide a cable broadcast receiving apparatus and method for allowing a user to watch a cable broadcast without having a separate cable card in the open cable standard.

The present invention allows the set-top box to process MPEG filtering, which is one of the functions of the cable card, so that the viewer can watch the broadcast without having a separate cable card. On the other hand, the present invention described below is based on the premise that can be implemented in a set-top box supporting a DSG mode for transmitting SI using a DOCSIS cable network.

Provided by the present invention, the set-top box of the DSG mode capable of acquiring channel information in the open cable method is a signal including the SI from the CMTS (Cable Modem Termination System) through the DOCSIS (Data-Over-Cable Service Interface Specifications) cable network A controller for generating an MPEG section table by performing MPEG filtering on a signal including a cable modem to be received and a signal received through the cable modem, and a navigator receiving the MPEG section table from the controller and searching for a broadcast channel. Set top box that includes.

In addition, the method for acquiring channel information using the set-top box configured as described above includes a first process of receiving a DSG packet through a cable network to which a DOCSIS scheme is applied, and acquiring a MAC address of a DSG tunnel in which the DSG packet is received. And a third process of performing MPEG PID filtering to map the obtained MAC address to the PID to obtain an MPEG section table for searching a broadcast channel.

Hereinafter, the terms used to describe the present invention are summarized as follows.

"DSG (DOCSIS System Gateway) mode" is one of cable broadcasting methods, and means a method of transmitting SI using a cable network to which the DOCSIS method is applied. In DSG mode, the SI may be received using a cable modem provided in the set-top box.

"MPEG Filtering" refers to a process of mapping broadcast data received through a broadcast channel with channel information (SI) received through an out-of-band channel. The viewer must perform MPEG filtering in order to receive the broadcast normally. The MPEG filtering process may be divided into a DSG tunnel MAC address acquisition process and an MPEG PID (Program IDentifier) filtering process.

The "MPE Section Table" is channel information on broadcast data received through a broadcast channel, which is obtained as a result of MPEG filtering, and thus normal broadcast reception is possible using the MPEG section table.

"Assembly" means a process of reassembling the partitioned table data. In loading table data in a DSG packet and transmitting it through a transmission medium, if one table data is larger than the size that can be carried in the DSG packet, the table data must be divided for transmission. The divided table data may be combined back into the original table data through an assembly process at the receiving side.

On the other hand, specific numerical values and addresses, etc. mentioned in the following description of the present invention are given to help the understanding of the present invention, and the present invention is not limited thereto. In addition, description about the function which is not related to this invention is abbreviate | omitted.

In order to carry out the present invention, the set-top box 140 should be able to acquire the DSG tunnel MAC address necessary for performing MPEG filtering and perform MPEG PID filtering. In addition, the set-top box 140 should be able to assemble the received DSG packet into the MPEG section table. The configuration of the set-top box 140 for this will be described with reference to FIG.

3 is a block diagram of a set-top box having a structure capable of performing MPEG filtering, which is a function of a cable card, according to the present invention.

The modem 212 of FIG. 3 receives a DSG packet including an SI transmitted by the CMTS 130 through a cable network to which the DOCSIS scheme is applied. The IP / Port routing module 214 performs MPEG filtering on the received DSG packet in addition to the existing call processing. The navigator 220 performs a search function for broadcast data received through a broadcast channel using the MPEG filtered MPEG section table received from the IP / Port routing module 214. The web module 216 and the network controller (NC) 218 shown in FIG. 3 may be used to provide additional services such as an Internet service.

First, a method of obtaining a DSG tunnel MAC address during MPEG filtering will be described.

The following three methods may be used to obtain the DSG tunnel MAC address without the cable card 200.

First, it is found through DSGTunnelEntry of MIB (Management Information Base) provided by a network management protocol (eg, Simple Network Management Protocol (SNMP)) that contains DSG MAC address information. DSGTunnelEntry of SNMP MIB includes information such as dsgInputAddressType, dsgInputAddress, dsgOutputAddress, and dsgTunnelNumber of this entry, and can use this information to construct DSG tunnel.

Second, the DSG MAC address used by the local broadcasting service provider is input by using a remote controller or the like when the set-top box 140 is installed. Basically, the cable card 200 supporting the DSG method has a well-known DSG MAC address in common, which is published. Therefore, the DSG tunnels in the same operator are the same, so that the user inputs and stores the DSG tunnel MAC address through the user interface (UI) or in the non-volatile memory area of the set-top box 140 instead of the installer. 140 can make use of this.

Third, the DSG tunnel descriptor is added to a Mac Management Message (MMM) used by the CMTS 130 to communicate with the cable modem 212. That is, the CMTS 130 broadcasts a DSG tunnel descriptor that describes a DSG tunnel MAC address in addition to the previously defined MAC control message, and the set-top box 140 supporting the DSG sends this MAC control message. You can construct DSG tunnels by analyzing them.

Next, the MPEG PID filtering process will be described.

In general, one DSG tunnel MAC address is mapped to one PID. For example of the DVS-178 system, SI (System Information) information such as a Master Guide Table (MGT), a Short-form Virtual Channel Table (SVCT), a Network Information Table (NIT), and the like are obtained using the same PID, and AEIT (Aggregate Event Information Table) / AETT (Aggregate Extended Text Table) comes down through another PID. Similarly, in the DSG method, SI information such as MGT, SVCT, and NIT comes down through the same DSG tunnel MAC address, and AEIT / AETT comes down through another same DSG tunnel MAC address. That is, it can be seen that there is a DSG tunnel MAC address mapped to each PID. The SI information received by the set top box 140 through the cable network to which the DOCSIS method is applied is transmitted through IP multicast through the CMTS 130 and the like, and has a form as shown in FIG. 4.

4 is a diagram illustrating a form of a DSG packet transmitted through a cable network to which a DOCSIS scheme is applied.

As shown in FIG. 4, the DSG packet includes an Ethernet header 300, an IP header 302, DSG data 304, and a CRC 306. The Ethernet header 300 included in the packet shown in FIG. 4 indicates that the packet is an IP packet transmitted through Ethernet. DSG data field 304 includes an MPEG section table, such as SI.

The table described in SCTE 65 is necessary for the navigator 220 for performing channel change and the like and for the program guide providing the SI information. Here, except for AEIT / AETT, all have the same 0x1ffc PID value and have a mapping value of table ID and table type of SIs received in the MGT. Therefore, if the table ID value is 0xc7, that is, the MGT table ID is analyzed by analyzing the data coming into the multiple DSG MAC tunnels, the found DSG tunnel MACs can be mapped to the 0x1ffc PID.

FIG. 5 is a diagram illustrating an example of an MGT that is a table used to map several tables and PIDs of an MPEG section table.

6 is a diagram illustrating an example of an AEIT that is one of the MPEG section tables.

A PID filtering process according to the present invention will be described with reference to FIGS. 5 and 6. After looking up the MGT table, the only thing we need to do for MPEG PID filtering is to find the AEIT / AETT section, which is not mapped to 0x1ffc. To this end, first, the contents of the MGT shown in FIG. 5 are analyzed to find AEIT and AETT having table type PIDs and table types mapped to each other. It then analyzes the data coming from the DSG tunnel that is not mapped to 0x1ffc and finds the MGT_tag with the table ID of 0xd6 (AEIT) and maps it to the table type PID that matches the lower 8 bits of the first table type found. For example, as a result of analyzing the contents of the MGT shown in FIG. 5, if an AEIT having a table type of 0x1000 and a table type PID of 0x1dd0 and an AEIT having a table type of 0x1003 and a table type PID of 0x1dd1 exist, first, a DSG not mapped to 0x1ffc After analyzing the data coming from the tunnel, find the AEIT with the table ID of 0xd6 and map the MGT_tag value of 0x00 to 0x1dd0 for the MGT_tag value of AEIT and map it to 0x1dd1 for the MGT_tag value of 0x03. If the same process is performed for AETT, the DSG tunnel MAC and PID are mapped to the entire SI.

Finally, we describe how to assemble DSG packets into MPEG section tables.

Even if the above-described mapping operation is completed, the DSG data obtained from the mapped DSG tunnel cannot be directly provided to the navigator 220. The maximum size of the MPEG section table is 4096 bytes. In this case, the MPEG section table is divided into several DSG packets instead of one DSG packet. For example, if a DSG packet is sent in the form of an Ethernet packet and the packet to be sent is larger than what can be included in the Ethernet packet, this MPEG section table must be divided into the size of the Ethernet packet for transmission. Therefore, the set top box 140 needs to assemble the DSG packet received as needed. In general, DSG packets are delivered through IP multicast or unicast, which means that they have a specific destination IP address and destination port of TCP / IP. Thus, it is possible to assemble a divided DSG packet into one MPEG section table by making a socket application having an IP address and a port of data entering each DSG tunnel. For example, if one DSG tunnel analysis shows that SI data multicasted to 224.0.0.1 is delivered to the set-top box 140 using UDP port 2000, the destination IP address is 224.0.0.1 and the destination port is 2000. Dynamically create a burn-in socket application to assemble forwarded DSG packets into an MPEG section table.

The above-mentioned contents are summarized in stages according to the operation of the present invention with reference to the drawings.

7 is a diagram according to the present invention and shows a process for watching a broadcast channel without a cable card.

In step 700, the set top box 140 obtains a DSG tunnel MAC address. The DSG tunnel MAC address acquisition method may include a method of using an MIB of SNMP, a method of inputting by a user using a user interface, and a method of using a MAC control message of a cable network to which a DOCSIS method is applied.

Steps 700 to 708 are MPEG PID filtering processes. In step 702, a DSG tunnel having an MGT is searched for. This is done through table ID lookup. In step 704, the DSG tunnel having the MGT searched in step 702 is mapped to a PID of 0x01ffc. In step 706, the MGT shown in FIG. 5 is analyzed to search for a table type and a table type PID. In step 708, an AEIT / AETT having a corresponding MGT tag is searched for in a DSG tunnel not mapped with 0x01ffc.

Steps 710 to 712 are processes for assembling the received table data. In operation 710, a socket application corresponding to a destination IP address and a destination port corresponding to each DSG tunnel is generated to process the MPEG section table. That is, in order to process an MPEG section table of up to 4096 bytes exceeding an Ethernet frame size, a DSG packet is driven by driving a socket application corresponding to a destination IP address and a destination port mapped to each DSG tunnel. Assemble to create the MPEG section table. In step 712, the MPEG section assembled data is loaded into the DSG packet in the socket application and transmitted to the navigator 220 or the SI parser. The MPEG section table can be transmitted to the navigator 220 or the SI parser to enable channel setting and the like.

As described above, the MPEG filtering is performed in the set-top box 140, and thus channel setting is possible, and the viewer can watch a desired broadcast without having a separate cable card 200. In addition, if the embedded CAS (Conditional Access System), which is a device capable of receiving only the subscribers who are qualified to receive the paid broadcasting service, is included in the set-top box 140, the scrambled channel can be viewed.

As described above, the present invention enables the set-top box to process the MPEG filtering that the cable card has conventionally performed so that the viewer can watch the desired broadcast without the cable card. This can reduce the cost incurred to have a cable card.

1 is a network diagram according to a DSG mode in which channel information is transmitted through a cable network to which a DOCSIS scheme is applied in an open cable standard.

Figure 2 is a view according to the prior art, the data flow of the cable card and set-top box for MPEG filtering.

3 is a block diagram of a set-top box having a structure capable of performing MPEG filtering which is a function of a cable card in accordance with the present invention.

4 is a diagram showing the form of a DSG packet transmitted through a cable network to which the DOCSIS scheme is applied.

FIG. 5 is a configuration diagram illustrating an example of an MGT that is a table used to map PIDs and various tables of an MPEG section table. FIG.

6 is a configuration diagram showing an example of an AEIT which is one of the MPEG section tables.

7 is a flowchart illustrating a process of performing MPEG filtering by a set-top box according to an embodiment of the present invention.

Claims (12)

A cable modem for receiving a signal including channel information from a cable modem termination system (CMTS) through a cable network to which a DOCSIS (Data-Over-Cable Service Interface Specifications) method is applied; A control unit for performing MPEG filtering on a signal including channel information received through the cable modem to generate an MPEG section table; The set top box of the DSG mode having a channel information acquisition function comprising a navigator for receiving the MPEG section table from the control unit to search for a broadcast channel. The MPEG filtering process of claim 1, wherein the MPEG filtering process is performed by the controller. Acquiring a MAC address of a DOGSIS System Gateway (DSG) tunnel in which the signal is received; Set-top box of the DSG mode having a channel information acquisition function including an MPEG PID filtering process for searching the table by mapping the DSG tunnel obtained the MAC address with a Program IDentifier (PID). The MPEG filtering process of claim 2, wherein the MPEG filtering process is performed by the controller. The set top box of the DSG mode having a channel information acquisition function further comprising an assembling process of combining the divided data received. The set top box of claim 3, wherein the assembling process is performed by generating a socket application using a destination IP address and a destination port included in a received DSG packet and recombining DSG data. 3. The set top box of claim 2, wherein the MAC address acquisition process of the DSG tunnel is performed by directly inputting the MAC address. 3. The set top box of claim 2, wherein the MAC address acquisition process of the DSG tunnel is performed by using a management information base (MIB) of a network management protocol. 3. The set top box of claim 2, wherein the MAC address acquisition process of the DSG tunnel is performed by using a MAC control message including a DSG tunnel descriptor. A first step of receiving a DSG packet through a cable network to which a DOCSIS scheme is applied; Obtaining a MAC address for the DSG tunnel in which the DSG packet is received; And performing an MPEG PID filtering to map the obtained MAC address to the PID to obtain an MPEG section table for searching a broadcast channel. The method of claim 8, further comprising a fourth process of performing an assembly process of recombining the MPEG section table when the MPEG section table is divided and received data. 9. The method of claim 8, wherein the second process is performed by directly inputting a MAC address in a set top box. The method of claim 8, wherein the second process is performed using a MIB of a network management protocol. 9. The method of claim 8, wherein the second process is performed by using a MAC control message including a DSG tunnel descriptor.