BACKGROUND OF THE INVENTION

Field of the Invention

The present disclosure relates to a broadcast signal transmission apparatus, a broadcast signal transmission method, a broadcast signal reception apparatus, and a broadcast signal reception method, and more particularly, to broadcast signal transmission/reception apparatuses and methods for processing data in a link layer.

Discussion of the Related Art

As analog broadcast signal transmission is terminated, various technologies for transmitting and receiving a digital broadcast signal have been developed. A digital broadcast signal is capable of containing a larger amount of video/audio data than an analog broadcast signal and further containing various types of additional data as well as the video/audio data.

That is, a digital broadcast system may provide a high definition (HD) image, multi-channel audio, and various additional services. However, for digital broadcasting, network flexibility needs to be enhanced in consideration of data transmission efficiency for a large amount of data transmission, robustness of a transceiving network, and a mobile receiving device.

DISCLOSURE OF THE INVENTION

Technical Problem

An object of the present disclosure is to provide a broadcast signal transmission apparatus, a broadcast signal transmission method, a broadcast signal reception apparatus, and a broadcast signal reception method, which are intended to efficiently compress and decompress a packet header for a large amount of data transmission and overhead reduction.

Another object of the present disclosure is to provide a broadcast signal transmission apparatus, a broadcast signal transmission method, a broadcast signal reception apparatus, and a broadcast signal reception method, which are intended to efficiently compress and decompress a header of Internet protocol (IP) packet.

Still another object of the present disclosure is to provide a broadcast signal transmission apparatus, a broadcast signal transmission method, a broadcast signal reception apparatus, and a broadcast signal reception method, which are intended to efficiently compress and decompress a header of IP packet in a robust header compression (ROHC) scheme.

Further still another object of the present disclosure is to provide a broadcast signal transmission apparatus, a broadcast signal transmission method, a broadcast signal reception apparatus, and a broadcast signal reception method, which are intended to efficiently process data in a link layer.

Technical Solution

A method of transmitting a broadcast signal according to an embodiment of the present disclosure may include outputting an RoHC channel that includes one or more RoHC streams and a signaling table that includes information related to header compression by performing header compression for IP packets, which include broadcast data, in accordance with an adaptation mode, a header of each IP packet including an IP header and a User Datagram Protocol (UDP) header, an encapsulation step of generating at least one first link layer packet that includes the RoHC channel and generating at least one second link layer packet that includes the signaling table, and physical layer processing the at least one first link layer packet and the at least one second link layer packet and transmitting through one or more Physical Layer Pipes (PLPs), the signaling table includes adaptation mode information indicating the adaptation mode.

According to embodiments of the present disclosure, each RoHC stream in the RoHC channel includes RoHC packets, when the RoHC packets include an Initialization and Refresh (IR) packet, an IR-Dynamic (IR-DYN) packet and compressed packets, the adaptation mode information indicates adaptation mode 1, when the RoHC packets include an IR-DYN packet and compressed packets, the adaptation mode information indicates adaptation mode 2, when the RoHC packets include compressed packets, the adaptation mode information indicates adaptation mode 3, and a value of a context identifier (CID) allocated to headers of the RoHC packets of the RoHC stream that includes the most RoHC packets among one or more RoHC streams in the RoHC channel is 0.

According to embodiments of the present disclosure, the signaling table further includes context information in the adaptation mode 2, the context information including static chain information of a first IP packet of an IP stream corresponding to the RoHC stream.

According to embodiments of the present disclosure, the signaling table further includes context information in the adaptation mode 3, the context information including static chain information and dynamic chain information of a first IP packet of an IP stream corresponding to the RoHC stream.

According to embodiments of the present disclosure, the adaptation mode 2 is selected when information included in headers of input IP packets is frequently updated, and the adaptation mode 3 is selected when information included in the headers of the input IP packets is not updated except a sequence number.

According to embodiments of the present disclosure, the CID is changed at the time when the signaling table is transmitted if a change of the CID is required.

According to embodiments of the present disclosure, performing header compression in accordance with the adaptation mode includes collecting IP packets when the IP packets are IP packets fragmented from an IP packet, recovering the collected IP packets to the IP packet prior to fragmentation and outputting the recovered IP packet for header compression.

According to embodiments of the present disclosure, performing header compression in accordance with the adaptation mode includes: classifying an IP stream by parsing a header of an input IP packet, generating a new context when there is no context of the classified IP stream, updating a context by detecting whether the context is updated when there is the context of the classified IP stream, and detecting a current state through a state machine, determining a packet type based on the detected current state, and generating an RoHC packet corresponding to one of an IR packet, an IR-DYN packet and a compressed packet based on a payload of the IP packet and the determined packet type, and generating and outputting the RoHC stream and the signaling table related to the RoHC stream to be output to the encapsulation step by repeatedly performing a procedure of extracting context information from the IR packet and/or the IR-DYN packet in accordance with the adaptation mode and a type of the generated RoHC packet and a procedure of converting the IR packet and/or the IR-DYN packet from which the context information is extracted, to the IR-DYN packet and/or the compressed packet for the IP packets of the classified IP stream.

According to embodiments of the present disclosure, performing header compression in accordance with the adaptation mode includes: classifying an IP stream by parsing a header of an input IP packet, generating a new context when there is no context of the classified IP stream, updating a context by detecting whether the context is updated when there is the context of the classified IP stream, and detecting a current state through a state machine, determining a packet type based on the detected current state, and generating an RoHC stream by repeatedly performing a procedure of generating an RoHC packet included in the RoHC stream to be output to the encapsulation step in accordance with the determined packet type, context information of the classified IP stream and the adaptation mode for IP packets of the classified IP stream, and generating signaling information related to the RoHC stream in accordance with the determined packet type, the context information of the classified IP stream and the adaptation mode.

According to embodiments of the present disclosure, a PLP for transmitting the at least one first link layer packet that includes the RoHC channel is different from a PLP for transmitting the signaling table.

According to embodiments of the present disclosure, the signaling table is an RoHC-U Description Table (RDT), and is categorized into a catalog RDT and a discrete RDT in accordance with a delivery type, when the catalog RDT includes a plurality of signaling tables, the plurality of signaling tables are continuously included in a payload of the at least one second link layer packet, and a number of signaling tables included in the payload is signaled to a header of the at least one second link layer packet.

An apparatus for transmitting a broadcast signal according to an embodiment of the present disclosure may include an IP header compressor for outputting an RoHC channel that includes one or more RoHC streams and a signaling table that includes information related to header compression by performing header compression for IP packets, which include broadcast data, in accordance with an adaptation mode, a header of each IP packet including an IP header and a UDP header, an encapsulation module for generating at least one first link layer packet that includes the RoHC channel and generating at least one second link layer packet that includes the signaling table, and a physical layer processor for physical layer processing the at least one first link layer packet and the at least one second link layer packet and transmitting through one or more Physical Layer Pipes (PLPs), the signaling table includes adaptation mode information indicating the adaptation mode.

According to embodiments of the present disclosure, each RoHC stream in the RoHC channel includes RoHC packets, when the RoHC packets include an IR packet, an IR-DYN packet and compressed packets, the adaptation mode information indicates adaptation mode 1, when the RoHC packets include an IR-DYN packet and compressed packets, the adaptation mode information indicates adaptation mode 2, when the RoHC packets include compressed packets, the adaptation mode information indicates adaptation mode 3, and a value of a CID allocated to headers of the RoHC packets of the RoHC stream that includes the most RoHC packets among one or more RoHC streams in the RoHC channel is 0.

According to embodiments of the present disclosure, the adaptation mode 2 is selected when information included in headers of input IP packets is frequently updated, and the adaptation mode 3 is selected when information included in the headers of the input IP packets is not updated except a sequence number.

According to embodiments of the present disclosure, the IP header compressor further includes a pre-processing module collects IP packets when the IP packets are IP packets fragmented from an IP packet, recovers the collected IP packets to the IP packet prior to fragmentation and outputs the recovered IP packet for header compression.

According to embodiments of the present disclosure, the IP header compressor includes: a context management module for classifying an IP stream by parsing a header of an input IP packet, generating a new context when there is no context of the classified IP stream, updating a context by detecting whether the context is updated when there is the context of the classified IP stream, and detecting a current state through a state machine, an RoHC packet generator for determining a packet type based on the detected current state, and generating an RoHC packet corresponding to one of an IR packet, an IR-DYN packet and a compressed packet based on a payload of the IP packet and the determined packet type, and an adaptation module for generating and outputting the RoHC stream and the signaling table related to the RoHC stream to be output to the encapsulation module by repeatedly performing a procedure of extracting context information from the IR packet and/or the IR-DYN packet in accordance with the adaptation mode and a type of the generated RoHC packet and a procedure of converting the IR packet and/or the IR-DYN packet from which the context information is extracted, to the IR-DYN packet and/or the compressed packet for the IP packets of the classified IP stream.

According to embodiments of the present disclosure, wherein the IP header compressor includes: a context management module for classifying an IP stream by parsing a header of an input IP packet, generating a new context when there is no context of the classified IP stream, updating a context by detecting whether the context is updated when there is the context of the classified IP stream, and detecting a current state through a state machine, an RoHC packet generator for determining a packet type based on the detected current state, and generating an RoHC stream by repeatedly performing a procedure of generating an RoHC packet included in the RoHC stream to be output to the encapsulation module in accordance with the determined packet type, context information of the classified IP stream and the adaptation mode for IP packets of the classified IP stream, and a signaling generator for generating signaling information related to the RoHC stream in accordance with the determined packet type, the context information of the classified IP stream and the adaptation mode.

According to embodiments of the present disclosure, a PLP for transmitting the at least one first link layer packet that includes the RoHC channel is different from a PLP for transmitting the signaling table.

According to embodiments of the present disclosure, the signaling table is an RDT, and is categorized into a catalog RDT and a discrete RDT in accordance with a delivery type, when the catalog RDT includes a plurality of signaling tables, the plurality of signaling tables are continuously included in a payload of the at least one second link layer packet, and a number of signaling tables included in the payload is signaled to a header of the at least one second link layer packet.

According to embodiments of the present disclosure, a method of receiving a broadcast signal may include receiving the broadcast signal including an RoHC stream that includes compressed packets and a signaling table related to the RoHC stream, wherein the RoHC stream is physical layer processed and received through a first PLP after encapsulated into at least one first link layer packet, wherein the signaling table is physical layer processed and received through a second PLP after encapsulated into at least one second link layer packet, wherein the signaling table includes header compression information related to the RoHC stream, adaptation mode information and context information, and wherein the context information includes static chain information and dynamic chain information corresponding to a first compressed packet of the RoHC stream, physical layer processing the broadcast signal, extracting the RoHC stream from the at least one first link layer packet received by the first PLP of the physical layer processed broadcast signal and extracting the signaling table from the at least one second link layer packet received by the second PLP of the physical layer processed broadcast signal, extracting a sequence number of a full length from the dynamic chain information of the signaling table, detecting compressed packets, which includes a same sequence number as lower 4 bits of the extracted sequence number from the RoHC stream, performing error validation based on CRC for the detected compressed packets based on the sequence number of the full length detected from the dynamic chain information, when there is a compressed packet that passes error validation based on CRC in the above step, starting decompression into an original IP packet based on the static chain information and dynamic chain information included in the signaling table and the passed compressed packet, and when there is no compressed packet that passes error validation based on CRC in the above step, starting decompression into an original IP packet based on the static chain information and dynamic chain information included in the signaling table and a second compressed packet of the RoHC stream.

According to embodiments of the present disclosure, the step of starting decompression based on the second compressed packet includes: checking whether UDP checksum is used, from the dynamic chain information, performing error validation based on CRC for the second compressed packet based on a sequence number of a full length corresponding to a sequence number of the second compressed packet of the RoHC stream when it is checked that UDP checksum is not used, and starting decompression into the original IP packet based on the static chain information and dynamic chain information included in the signaling table and the second compressed packet when the second compressed packet passes error validation based on CRC.

According to embodiments of the present disclosure, the signaling table is an RDT, and is categorized into a catalog RDT and a discrete RDT in accordance with a delivery type, when the catalog RDT includes a plurality of signaling tables, the plurality of signaling tables are continuously included in a payload of the at least one second link layer packet, and a number of signaling tables included in the payload is signaled to a header of the at least one second link layer packet.

Advantageous Effects

According to the present disclosure, an IP header compression procedure may be simplified to reduce complexity of a broadcast system.

According to the present disclosure, context information is extracted from IR packets and/or IR-DYN packets in accordance with an adaptation mode during header compression of IP packets, and a procedure of converting the IR packets and/or IR-DYN packets, from which the context information is extracted, to IR-DYN and/or compressed packets is omitted, and packets of compressed IP streams and RDT are generated, whereby hardware complexity is reduced.

According to the present disclosure, if UDP checksum is not used, even though a first compressed packet of the compressed IP streams is missed at a receiving side, next compressed packet is used for decompression without being discarded, whereby it is not required to wait for next RDT to start decompression and therefore a decompression time is shortened.

According to the present disclosure, IP fragmentation applied in a transmission system is avoided prior to transmission to a reception system, whereby implementation of the reception system may be simplified.

According to the present disclosure, bandwidth reduction of IP header compression may be increased effectively.

