WO2019143208A1 - Apparatus and method for communication in broadcast system - Google Patents

Abstract

The present disclosure relates to a communication apparatus and method for supporting a forward error correction scheme in a communication system. To this end, by means of a generation mode among a plurality of generation modes (ssbg_mode #0, #1, #2), a source symbol block having a plurality of source symbols is generated by using a source packet block having a plurality of source packets, and a repair symbol block for the generated source symbol block is generated by means of a forward error correction (FEC) scheme among a plurality of FEC schemes (FEC payload ID mode 0, FEC payload ID mode 1). A first FEC scheme (FEC payload ID mode 1) is applied to generate the repair symbol block, and in response to an occurrence of a discontinuity in packet sequence numbers, a repair packet may be generated to include length repair data and a repair FEC payload identifier (ID).

Description

Communication apparatus and method in broadcasting system

The present disclosure relates to a communication apparatus and method supporting a forward error correction scheme in a communication system.

In general, a broadcasting system uses error correction schemes to support the recovery of lost data in a receiving apparatus when data is lost on the network. A forward error correction (FEC) scheme is a typical error correction scheme that enables a receiving apparatus to recover lost data. The FEC scheme can be classified in consideration of the layer to which it is applied. The application layer forward error correction (AL-FEC) scheme is an FEC scheme in which FEC processing is performed in the application layer.

The FEC scheme may, for example, provide redundant information to a receiving apparatus for use by a transmitting apparatus to recover lost information. Here, the surplus information can be generated by using a promised algorithm between the transmitting apparatus and the receiving apparatus. The algorithm may generate surplus information with source information as an input.

In the transmission apparatus of the broadcasting system to which the FEC scheme is applied, FEC coding can be performed on a plurality of source symbols constituting a source symbol block to obtain repair symbols. To do this, it is necessary to change a number of source packets constituting a source packet block to a plurality of source blocks constituting a source symbol block. The source packet may be an MMT packet when using, for example, a moving picture experts group (MPEG) media transport (hereinafter referred to as "MMT ") protocol.

The source symbols may have the same length, while the source packets may be of varying length. If the length of one source packet is greater than the length of one source symbol, the one source packet may be divided into a plurality of source symbols. Also, one source symbol may maintain the same length using padding data.

Accordingly, in order to recover the lost source packet using the source symbol block decoded by the receiving apparatus, it is required to specify the source symbols constituting the lost source packet and to prepare a method for removing the padding data.

One aspect of the present disclosure is to provide a method and apparatus for transmitting / receiving packets in a broadcast system.

It is also an aspect of the present disclosure to provide a packet sending / receiving method and apparatus for increasing data recovery efficiency in a broadcast system.

Still another aspect of the present disclosure is to provide a packet transmission / reception method and apparatus capable of achieving efficient transmission reliability in a broadcasting system.

According to another aspect of the present disclosure, there is provided a method and apparatus for transmitting / receiving data to a receiving apparatus in a broadcasting system in which a receiving apparatus can identify source symbols corresponding to the source packet in a source block have.

Still another aspect of the present disclosure is to provide a transmitting / receiving method and apparatus capable of finding a starting point of a lost source packet in source symbols of a recovered source symbol block in a broadcasting system.

Yet another aspect of the present disclosure is to provide a transmitting / receiving method and apparatus capable of removing padding data from source symbols of a source symbol block, which is partially or fully recovered in a broadcasting system.

Still another aspect of the present disclosure is to provide a transmitting / receiving method and apparatus capable of recovering all source packets by source symbols of a source symbol block that is partially or fully recovered in a broadcasting system.

A method of generating a transmission packet in a broadcasting system according to an embodiment of the present disclosure includes generating a plurality of source packets by a generation mode of one of a plurality of generation modes (ssbg_mode # 0, # 1, # 2) Generating a source symbol block having a plurality of source symbols by using a source packet block having a plurality of forward error correction (FEC) modes (FEC payload ID mode 0, FEC payload ID mode 1) Generating a repair symbol block for the generated source symbol block by one FEC scheme; generating a source packet by the plurality of source packets; and generating a repair packet by the generated repair symbol block And a step of generating,

Here, the process of generating the repair packet may include a first FEC scheme (FEC payload ID mode 1) to generate the repair symbol block, a length repair data and a repair FEC And generating the repair packet so as to include a payload identifier (ID).

The transmitter of the broadcasting system according to an embodiment of the present disclosure includes a transmitter for transmitting a transmission packet to an external device for a broadcasting service and a transmitter for transmitting the transmission packet for the broadcasting service, / RTI >

Here, the at least one processor may be configured to use a source packet block having a plurality of source packets by a generation mode of one of a plurality of generation modes (ssbg_mode # 0, # 1, # 2) A source symbol block is generated and the repair for the generated source symbol block is performed by one FEC scheme among a plurality of forward error correction (FEC) methods (FEC payload ID mode 0, FEC payload ID mode 1) A first FEC scheme (FEC payload ID mode 1) is applied to generate a symbol block, a source packet by the plurality of source packets, and to generate the repair symbol block, and a disconnection of a packet sequence number And generating the repair packet to include the length repair data and the repair FEC payload identifier (ID) in response to the repair packet.

A method for recovering a transmission packet in a broadcasting system according to an embodiment of the present disclosure includes receiving a source packet including a plurality of source packets and a repair packet including a repair symbol block, (FEC payload ID mode 0, FEC payload ID (FEC payload ID)) to generate the repair symbol block based on a plurality of flags included in a repair forward error correction (FEC) payload identifier (FEC payload ID mode 1) of a packet sequence number 1 is applied to the first FEC scheme (mode 1), and the first FEC scheme (FEC payload ID mode 1) Decoding length repair data of the repair packet in response to occurrence of a sequence number disconnection; And recovering the transport packet,

The plurality of flags may include a first flag (D) indicating discontinuation of the packet sequence number, a second flag (I) indicating that the repair packet includes the length repair data, A third flag (F: FEC_parameter_flag) indicating whether the same FEC code is used for generation of the repair symbol block and generation of the length repair data, and the number of repair symbols included in the length repair data, And a fourth flag (N: num_LRS_flag) indicating that the number of repair symbols included is the same,

Here, the repair FEC payload identifier (ID) may further include information on a length set in consideration of the first to fourth flags.

A receiving apparatus of a broadcasting system according to an embodiment of the present disclosure includes a receiver for receiving a source packet including a plurality of source packets and a repair packet including a repair symbol block, And a processor for recovering the received source packet,

The at least one processor may further include a plurality of FECs to generate the repair symbol block based on a plurality of flags included in a repair forward error correction (FEC) payload identifier (ID) of the repair packet. A first FEC scheme (FEC payload ID mode 1) among the FEC payload ID mode 0 and FEC payload ID mode 1 is applied to identify whether a packet sequence number is disconnected, ID mode 1) is applied, the length repair data of the repair packet is decoded in response to the occurrence of the disconnection of the packet sequence number, the recovered transport packet is recovered using the decoded length repair data,

The plurality of flags may include a first flag (D) indicating discontinuation of the packet sequence number, a second flag (I) indicating that the repair packet includes the length repair data, A third flag (F: FEC_parameter_flag) indicating whether the same FEC code is used for generation of the repair symbol block and generation of the length repair data, and the number of repair symbols included in the length repair data, And a fourth flag (N: num_LRS_flag) indicating that the number of repair symbols included is the same,

Here, the repair FEC payload identifier (ID) may further include information on a length set in consideration of the first to fourth flags.

Further aspects, features and advantages of the present invention as set forth above in connection with certain preferred embodiments of the present disclosure will become more apparent from the following description, taken in conjunction with the accompanying drawings, in which:

1 illustrates a hierarchical structure of an electronic device supporting broadcast services to which various embodiments proposed in this disclosure apply;

Figure 2 illustrates a two-stage FEC encoding scheme to which various embodiments proposed in this disclosure may be applied;

FIG. 3 illustrates a method of generating a source symbol block in an LA-FEC encoding structure having two layers to which various embodiments proposed in the present disclosure can be applied; FIG.

4 illustrates an example of an encoded symbol block in a broadcast system according to an embodiment of the present disclosure;

5 illustrates an example of a source symbol block generated using ssbg_mode0 in a broadcast system according to an embodiment of the present disclosure;

6 illustrates an example of a source symbol block generated using ssbg_mode 1 in a broadcast system according to an embodiment of the present disclosure;

7 illustrates an example of a source symbol block generated using ssbg_mode 2 in a broadcast system according to an embodiment of the present disclosure;

8 illustrates an example of a FEC source packet format in a broadcast system according to an embodiment of the present disclosure;

9 illustrates an example of an FEC repair packet format in a broadcast system according to an embodiment of the present disclosure;

10 illustrates an example of a source FEC payload ID in a broadcast system according to one embodiment of the present disclosure;

11 is a diagram illustrating an example of a SS_ID setting method when an LA-FEC coding scheme is used in a broadcasting system according to an embodiment of the present disclosure;

12 illustrates an example of a repair FEC payload ID in a broadcast system according to an embodiment of the present disclosure;

13 is a diagram illustrating an example of generating a source symbol block in a source packet block using ssbg_mode 2 in a communication system according to an embodiment of the present disclosure;

FIG. 14 illustrates another example of an FEC repair packet format in a broadcast system according to an embodiment of the present disclosure; FIG.

15 illustrates an example of a repair FEC payload ID in a broadcast system according to an embodiment of the present disclosure;

16 illustrates an example of a source symbol block generated using ssbg_mode2 in a broadcast system according to an embodiment of the present disclosure;

FIG. 17 illustrates an example of a length symbol block for packet length information protection in a broadcast system according to an embodiment of the present disclosure; FIG.

18 illustrates an example of an encoding symbol block when a packet drop is applied in a broadcasting system according to an embodiment of the present disclosure;

19 is a diagram illustrating an example of a length-encoded symbol block when a packet drop is applied in a broadcasting system according to an embodiment of the present disclosure;

20 is a flowchart illustrating an operation procedure of a transmitting apparatus in a broadcasting system according to an embodiment of the present disclosure;

FIG. 21 illustrates an operation procedure of a receiving apparatus in a broadcasting system according to an embodiment of the present disclosure; FIG.

22 schematically illustrates an internal structure of a transmitting apparatus in a broadcasting system according to an embodiment of the present disclosure; And

23 is a view schematically showing an internal structure of a receiving apparatus in a broadcasting system according to an embodiment of the present disclosure.

Throughout the drawings, it should be noted that like reference numerals are used to illustrate the same or similar elements and features and structures.

Hereinafter, various embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be understood, however, that this disclosure is not intended to limit the present disclosure to the particular embodiments, but includes various modifications, equivalents, and / or alternatives of the embodiments of the present disclosure. In connection with the description of the drawings, like reference numerals may be used for similar components.

In this document, the expressions "having ", " having ", " including ", or & And does not exclude the presence of additional features.

In this document, the expressions "A or B," "at least one of A and / or B," or "one or more of A and / or B," may include all possible combinations of the items listed together. For example, "at least one of A or B," "at least one of A and B," or "at least one of A or B" includes (1) at least one A, (2) at least one B, (3) at least one A and at least one B all together.

Expressions such as " first, " " second, " " first, " or " second, " etc. used in various embodiments may denote various components irrespective of order and / or importance, I never do that. The representations may be used to distinguish one component from another. For example, the first user equipment and the second user equipment may represent different user equipment, regardless of order or importance. For example, without departing from the scope of the present disclosure, the first component may be referred to as a second component, and similarly, the second component may be named as the first component.

(Or functionally or communicatively) coupled with / to "another component (eg, a second component), or a component (eg, a second component) Quot; connected to ", it is to be understood that any such element may be directly connected to the other element or may be connected through another element (e.g., a third element). On the other hand, when it is mentioned that a component (e.g., a first component) is "directly connected" or "directly connected" to another component (e.g., a second component) It can be understood that there is no other component (e.g., a third component) between other components.

As used herein, the phrase " configured to " (or set) to be "adapted to, " "" Designed to, "" adapted to, "" made to, "or" capable of "can be used. The term " configured (or set) to "may not necessarily mean " specifically designed to" Instead, in some situations, the expression "configured to" may mean that the device can "do " with other devices or components. For example, a processor configured (or configured) to perform the phrases "A, B, and C" may be a processor dedicated to performing the operation (e.g., an embedded processor), or one or more software programs To a generic-purpose processor (e.g., a CPU or an application processor) that can perform the corresponding operations.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the other embodiments. The singular expressions may include plural expressions unless the context clearly dictates otherwise. All terms used herein, including technical or scientific terms, may have the same meaning as commonly understood by one of ordinary skill in the art of the present disclosure. Commonly used predefined terms may be interpreted to have the same or similar meaning as the contextual meanings of the related art and are not to be construed as ideal or overly formal in meaning unless expressly defined in this document . In some cases, the terms defined herein may not be construed to exclude embodiments of the present disclosure.

Various embodiments to be proposed below will be described in detail with reference to the accompanying drawings.

1 is a diagram showing a hierarchical structure of an electronic device supporting broadcast services to which various embodiments proposed in the present disclosure are applied.

Referring to FIG. 1, an electronic device may have a structure in which AL-FEC is applied, for example, in an MMT. That is, the electronic device may have a hierarchical structure including an MMT application layer, a protocol layer, a transport layer, and an internet protocol (IP) layer. The electronic device may be, for example, a transmitting device or a receiving device supporting a broadcasting service.

The transmitting device determines the number of FEC source flows to protect the assets and the assets that need protection in the MMT package. One FEC source flow can protect one or more assets. The FEC source flow may consist of MMTP packets carrying one or more assets. The FEC source flow and its configuration information may be delivered in an FEC scheme.

The FEC scheme may use one or more FEC codes to generate repair symbols that constitute one or more FEC repair flows. The repair symbols may be delivered to the receiving device along with the FEC payload ID based on the MMT protocol. That is, the transmitting apparatus can forward the FEC source packets and the FEC repair packets to the receiving apparatus using the MMT protocol.

The MMT protocol of the receiving device may forward the FEC source flow and one or more FEC repair flows related to the FEC source flow in an FEC scheme. The FEC method may attempt to restore the lost MMTP packets and forward the restored MMTP packets to the MMT protocol.

The FEC scheme proposes a method of dividing an FEC source flow into source packet blocks and generating source symbol blocks by the source packet blocks. The generated source symbol blocks are FEC-encoded by FEC codes. Here, FEC encoding means to generate a repair symbol block composed of repair symbols using a source symbol block composed of source symbols. The FEC encoding algorithm can be used to create repair symbol blocks in source symbol blocks. For example, the FEC encoding algorithm described in ISO / IEC 23008-10 can be used.

The FEC scheme can operate in one of two different modes: FEC payload ID mode 0 and FEC payload ID mode 1. The FEC payload ID mode 0 adds the source FEC payload ID to the MMTP packet, and the FEC payload ID mode 1 does not modify the existing MMTP packet.

The FEC scheme can use a FEC encoding scheme to construct multi-level packets including layered or non-layered media data. This makes it possible to apply as many protection levels as necessary to each asset that constitutes one FEC source flow. The FEC source flow may be an MMTP subflow that carries a signaling message. The FEC encoding structure may include, for example, a two-stage FEC encoding structure and a layer-aware FEC (LA-FEC) encoding structure.

2 is a diagram illustrating a two-stage FEC encoding scheme to which various embodiments proposed in this disclosure may be applied.

Referring to FIG. 2, one source packet block 210 may be divided into M (> 1) source packet blocks 220-1, 220-2... 220-M. The divided source packet blocks 220-1, 220-2, ..., and 220-M may be divided into M source symbol blocks (i. E., M) by one of a plurality of source symbol block generation modes (ssbg modes) (230-1, 230-2, ..., 230-M). Each of the M source symbol blocks 230-1, 230-2,... 230-M is encoded using a first FEC code 240.

M source symbol blocks 230-1, 230-2, ..., 230-M to generate a single source symbol block 230, and transmits the generated single source symbol block 230 to a second FEC code 250). ≪ / RTI >

The M repair symbol blocks 1 ^st _P 1 and 2 ^nd _P 1 are generated by coding each of the M source symbol blocks 230 - 1, 230 - 2, and 230 -M using the first FEC code 240. ... M ^th _P1) are generated. The single source symbol block 230 is coded using the second FEC code 250 to generate one repair symbol block P2.

The LA-FEC encoding structure is an FEC encoding structure specialized for layered media data (e.g., SVC, MVC, etc.). The LA-FEC encoding scheme utilizes the association between media layers, and each media layer has an associated FEC repair flow. Where the FEC repair flow protects both the data of the associated media layer and all media layers (hereinafter referred to as complementary layers) on which the associated media layer depends.

In the LA-FEC coding structure, source packets including data of each media layer are grouped into different source symbol blocks for each layer. The source symbol blocks used for generating the repair symbols constituting one FEC repair flow are composed of the source symbol blocks constituted by the data of the media layer associated with the FEC repair flow and the source symbol blocks constituted by the supplementary layer data of the associated media layer It is a combined form. The combination of source symbol blocks composed of data of different layers follows the hierarchical structure of the media. That is, each source symbol block may follow a source symbol block composed of supplementary layer data of the media data included in the source symbol block.

The source symbol block and the repair symbol block generated according to the above description constitute one encoding symbol block and the repair symbol block P2 generated from the single source symbol block 230 may be combined with the one encoding symbol block have.

3 is a diagram illustrating a method of generating a source symbol block in an LA-FEC encoding structure having two layers to which various embodiments proposed in the present disclosure can be applied.

In FIG. 3, an enhancement layer (Enh. Layer) indicates a layer that depends on a base layer in a layered media stream.

4 is a diagram showing an example of an encoding symbol block in a broadcasting system according to an embodiment of the present disclosure.

Referring to FIG. 4, the encoded symbol block is composed of a source symbol block and a repair symbol block generated by the source symbol block. The source symbol block may be configured according to a scheme promised by the transmitting apparatus and the receiving apparatus.

In the broadcasting system, for example, one or more source symbol block generation methods may be defined, and one of them may be selected as needed to generate a source symbol block. Hereinafter, the source symbol block generation method is referred to as an SSBG mode (source symbol block generation mode). The SSBG mode selected by the transmitting apparatus can be transmitted to the receiving apparatus through a signaling message.

According to one embodiment, an encoding symbol block is composed of a source symbol block including K source symbols and a repair symbol block including P repair symbols. It is noted that the length of the source symbols and the repair symbols belonging to the encoded symbol block is equal to T byte.

In the broadcasting system supporting the multimedia service, the FEC source flow is divided and protected by the source packet block unit. The source packets belonging to the source packet block may have a fixed or variable length. The source packet block may be converted into a source symbol block according to the SSBG mode for FEC encoding.

The broadcasting system supporting the multimedia service may use, for example, three types of SSBG modes called ssbg_mode0, ssbg_mode1, and ssbg_mode2. The ssbg_mode0 may be used only when all the MMT packets constituting one source packet block have the same length. The ssbg_mode 1 and the ssbg_mode 2 may be used when the MMT packets constituting one source packet block have different lengths.

Hereinafter, embodiments in which FEC payload ID mode 0 is applied will be described with reference to FIGS. 5 to 12, and embodiments in which FEC payload ID mode 1 is applied will be described with reference to FIG. 13 to FIG.

5 is a diagram illustrating an example of a source symbol block generated using ssbg_mode 0 in a broadcast system according to an embodiment of the present disclosure.

Referring to FIG. 5, when ssbg_mode 0 is used, all MMT packets constituting one or a plurality of source packet blocks (M) may have the same length. In this case, the number (K) of the source symbols constituting the source symbol block coincides with the number (K) of the source packets constituting the source packet block, that is, the number of MMT packets. For example, it indicates that the i-th MMT packet of the source packet block is the same as the i-th symbol of the source symbol block (i = 0, 1 ... K-1). When the two-stage FEC coding structure or the LA-FEC coding structure is applied (M > 1), the i-th source symbol block is generated from the ith source packet block (i = One).

6 is a diagram illustrating an example of a source symbol block generated using ssbg_mode 1 in a broadcast system according to an embodiment of the present disclosure.

Referring to FIG. 6, when ssbg_mode 1 is used, each source symbol constituting a source symbol block may include a padding byte if necessary, so that it can be equal to the length of an MMT packet associated with the source symbol. With the exception of this point, a source symbol block can be generated in the same manner as ssbg_mode 0. That is, the number (K) of MMT packets included in one source packet block is equal to the number (K) of source symbols included in one source symbol block associated with the one source packet block.

According to ssbg_mode 1, the i-th source symbol of the source symbol block may start with two octets arranged in network byte order (upper octet first) indicating the length of the i-th MMT packet of the associated source packet block. The octets of the MMT packet #i are then arranged and the remaining part is filled with 0 octets.

When a two-stage and LA-FEC coding structure (M> 1) is used, the i-th source symbol block is generated from the i-th source packet block (i = 0, 1 ... M-1) The source symbols belonging to the source symbol block may contain the padding byte (00h) at the end.

7 is a diagram illustrating an example of a source symbol block generated using ssbg_mode 2 in a broadcast system according to an embodiment of the present disclosure.

Referring to FIG. 7, the lengths of 5 MMT packets constituting one source packet block are 34, 30, 56, 40 and 48 bytes, respectively, and the 5 MMT packets are composed of 8 source May be placed in the source symbols. In this case, the size (T) of the source symbol is 32, and each source symbol can be composed of two symbol elements (T '= T / 2 = 16 bytes).

According to one embodiment, one source symbol block in ssbg_mode 2 may be generated from a source packet block containing Ksp source packets. The one source symbol block may include Kss source symbols. All source symbols may equally include N symbol elements. This means that one source symbol block is composed of N * Kss symbol elements.

The MMT packet # 0 of the source packet block may be located in the first s0 symbol elements of the associated source symbol block.

More specifically, the first two bytes of the first of the s0 symbol elements may begin with two octets of the network byte order indicating the length of MMTP packet # 0. The octets of MMTP packet # 0 are then filled in, and the remaining part is filled with zero octets. The first MMT packet of the source packet block may be placed in the next s1 symbol elements in the source symbol block like the 0th MMT packet. If the Kss * T-sum {si * T / N, i = 0 ...... Ksp-1} is not 0 after filling up the MMT packet # Ksp-1 in the same manner, Lt; RTI ID = 0.0 > symbol < / RTI >

In the two-stage and LA-FEC coding coding schemes, a single source symbol block for the second FEC code is generated by concatenating all the source symbol blocks generated from the M source packet blocks.

Definition of specific values in SSBG mode

- Ksp: number of MMT packets (source packets) in the source packet block

- Kss: the number of source symbols in the source symbol block

- Ri: Octet of the ith MMT packet to be added to the source symbol block

- Si: length of Ri expressed in octets

- Li: Si value in two octets of network byte order

- T: source symbol size expressed in bytes

- N: the number of symbol elements that make up one source symbol

- T ': size of symbol element expressed in bytes (T' = T / N)

the smallest integer satisfying - si: si * T / N = siT '> = (Si + 2)

- Pi: si * T'- (Si + 2) zero octets

- P: Kss * T-sum {si * T ', i = 0 ...... Ksp-1} zero octets

At this time, the source symbol block may be divided into source symbols of size T after sequentially connecting P, Li, Ri, Pi (i = 0, ..., Ksp-1)

The MMTP packet, which is one of the transmission packets in the broadcasting system providing the multimedia service, can be divided into the FEC source packet and the FEC repair packet. The FEC source packet has a format for transmitting a source packet, and the FEC repair packet has a format for transmitting a repair symbol.

8 is a diagram showing an example of the FEC source packet format in the broadcasting system according to the embodiment of the present disclosure.

Referring to FIG. 8, the FEC source packet may have a format in which a source FEC payload ID is added to an MMTP packet including an MMTP packet header, an MMTP payload header, and an MMTP payload. The source FEC payload ID may provide information for identifying the source symbol or symbol element carried by the FEC source packet.

9 is a diagram showing an example of an FEC repair packet format in a broadcast system according to an embodiment of the present disclosure.

Referring to FIG. 9, an FEC repair packet may have a format including an MMTP packet header, a repair FEC payload ID, and one or more repair symbol (s). The repair FEC payload ID may provide information for identifying the repair symbol (s) and the associated source packet block included in the FEC repair packet.

If ssbg_mode 0 or ssbg_mode 1 is used, the FEC repair packet should contain only one repair symbol. If ssbg_mode 2 is used, the FEC repair packet may contain one or more repair symbols.

One or more of the remaining FEC repair packets excluding the last FEC repair packet among the FEC repair packets belonging to the FEC repair packet block should include the same number of repair symbols.

According to one embodiment, a transmitting apparatus using the MMT FEC technique must transmit information (hereinafter referred to as 'FEC configuration information') required for restoring a lost source packet to the receiving apparatus. The FEC configuration information may include a source FEC payload ID. The FEC configuration information may be included in an FEC source packet and / or an FEC repair packet depending on its use and characteristics. The FEC configuration information may be transmitted as a separate packet for a signaling message other than the FEC source packet and the FEC repair packet.

10 is a diagram illustrating an example of a source FEC payload ID in a broadcast system according to an embodiment of the present disclosure;

An example of the usage of the SS_ID field and the FFSRP_TS field in FIG. 10 is as follows.

SS_ID (32 bits) - indicates a sequence number that can identify source symbols included in the FEC source packet. This serial number returns to zero after the maximum value.

If ssbg_mode 0 or ssbg_mode 1 is used, the SS_ID value is incremented by 1 for each FEC source packet. If ssbg_mode == 10, the serial number is incremented by one for each symbol element (including symbol elements consisting of padding only), and the SS_ID value is set to the serial number of the first symbol element contained in the corresponding FEC source packet.

When the LA-FEC coding structure is used, the lowest SS_ID of the source symbol block should be equal to SS_ID_max + 1. Where SS_ID_max is the highest SS_ID of the preceding source symbol block of all flows.

11 is a diagram illustrating an example of an SS_ID setting method when an LA-FEC coding scheme is used in a broadcasting system according to an embodiment of the present disclosure.

Referring to FIG. 11, the first SS_ID of the same source symbol block in each flow can be used as a synchronization point of all source symbol blocks of all flows.

FFSRP_TS (4 bytes) - FFSRP_TS consists of TS_Indicator (1 bit) and FP_TS (31 bits).

TS_Indicator (1 bit) - Indicates the time stamp in the FEC (see Table 1). For the one-stage FEC encoding scheme and LA-FEC, the value of this field shall be set to "0".

In the case of a two-stage FEC encoding structure (M > 1), if set to "1 ", it indicates that FP_TS (31 bits) is a value for an FEC source or repair packet block.

If the FP_TS (31 bits) is set to "0 ", the next FEC source or repair packet block (M > 1 and i = 1, 2 ... M) of the two- Value.

In the case of the two-stage FEC encoding structure (M > 1), this field is set to "0" for odd-numbered FEC source packets of the i-th FEC source packet block, For source packets, it should be set to "1" (i = 1, 2 ... M).

Table 1 below describes the values of TS_Indicator.

FP_TS (31 bits) - FP_TS indicates the remaining 31 bits excluding the MSB in the 32-bit time stamp existing in the packet header of the MMTP packet transmitted first in the related FEC source packet block / FEC repair packet block.

According to one embodiment, the FFSRP_TS may optionally exist. The signaling message transmitted in a separate packet excluding the FEC source / repair packet may include, for example, a flag indicating whether the FFSRP_TS is present.

The repair FEC payload ID in the FEC configuration information may exist after the MMTP packet header in the FEC repair packet as in the example of the FEC repair packet format shown in FIG.

12 is a diagram illustrating an example of a repair FEC payload ID in a broadcast system according to an embodiment of the present disclosure.

Each field in Fig. 12 can be defined as follows.

SS_Start (32 bits) - Indicates the boundary of the associated source symbol block. If ssbg_mode 0 or ssbg_mode 1 is used, it is set to the serial number of the first source symbol of the associated source symbol block. If ssbg_mode 2 is used, it is set to the serial number of the first symbol element of the associated source symbol block.

RSB_length (24 bits) - The number of all repair symbols of the repair symbol block including one or a plurality of repair symbols transmitted in the FEC repair packet.

RS_ID (24 bits) - A serial number for identifying the first repair symbol included in the FEC repair packet. If the corresponding FEC repair packet includes more than two repair symbols, the serial number of one or more subsequent repair symbols of the first repair symbol increases by one. This is because the serial number is given by incrementing by one from 0 for repair symbols included in each repair symbol block.

SSB_length [N] (N * 24 bits) - When the LA-FEC coding structure is not used, N is "1" and SSB_length is the number of source symbols (ssbg_mode 0 or ssbg_mode 1 included in the associated source symbol block ) Or the number of source symbol elements included in the associated source symbol block (in the case where ssbg_mode 2 is used, excluding the source symbol element consisting entirely of padding).

When the LA-FEC coding structure is used, N should be equal to the number of complementary layers + 1, and SSB_length [i] is the number of source symbols included in the associated source symbol block of the i-th flow (ssbg_mode 0 or ssbg_mode 1 ) Or the number of symbol elements included in the associated source symbol block of the i-th flow (in the case where ssbg_mode 2 is used, the entire source symbol element constituted by padding is excluded).

FFSRP_TS (4 bytes) - TS_Indicator (1 bit) and subsequent FP_TS (31 bits).

TS_Indicator (1 bit) - Indicates the time stamp in the FEC (see Table 2). For the one-stage FEC encoding scheme and LA-FEC, the value of this field shall be set to "0". For a two-stage FEC coding structure (M > 1), the value of this field indicates the use for FP_TS (31 bits). That is, when the value of this field is set to "1", this indicates that the FP_TS (31 bits) is a value for the FEC source or repair packet block. If the value of this field is set to "0 ", the next FP_TS (31 bits) is stored in the i-th FEC source or repair packet block (M > 1 and i = M). ≪ / RTI >

In the case of the two-stage FEC coding structure (M > 1), this field is set to "0" for the odd-numbered FEC source packets of the i-th FEC source packet block, Can be set to "1" for source packets (i = 1, 2 ... M).

Table 2 below defines the value of TS_Indicator.

FP_TS (31 bits) - indicates the remaining 31 bits excluding the MSB in the 32-bit time stamp existing in the packet header of the MMTP packet transmitted first in the related FEC source packet block / related FEC repair packet block.

The AL-FEC message conveys the AL-FEC configuration information to the receiver or network entity.

<Table 3> to <Table 5> are examples of the format of the AL-FEC message.

Table 3 to Table 5 describe the use of each field constituting the AL-FEC message.

message_id - An identifier to identify the AL-FEC message.

version - Version information of the AL-FEC message.

length - A 16-bit field representing the length in bytes of the AL-FEC message. Indicates the length from the next field to the last byte of the AL-FEC message, where 0 is not allowed.

fec_flag - Indicates whether there is at least one source flow protected by AL-FEC. If no source flow is protected by AL-FEC, the following message is not delivered.

Table 6 below defines values of the fec_flag field.

private_fec_flag - Indicates the presence of private FEC information. If the value is "0 ", it indicates that no FEC code identified in the subsequent fec_code_id_for_repair_flow field requires private FEC information. If the value is "1 ", presence / absence of private FEC information and its length are provided using at least 1 byte (private_flag and private_field_length) for all FEC codes identified by the following fec_code_id_for_repair_flow field.

length_of_fec_flow_descriptor - length in bytes of fec_flow_descriptor

number_of_fec_flows - the number of FEC encoded flows (FEC encoded flows)

fec_flow_id - an integer value to identify the FEC encoded packet flow. Each FEC encoded packet flow has one FEC source flow associated with it and one or more FEC repair flows.

source_flow_id - An integer value to identify the FEC source flow. Each FEC source flow has one associated FEC encoded packet flow.

number_of_assets - The number of assets the FEC source flow contains.

packet_id - The value of the packet_id field in the MMTP packet header.

ssbg_mode-The SSBG mode value.

Table 7 below defines the valid values of the ssbg_mode field.

ffsrpts_flag - Indicates whether FFSRP_TS (32 bits) is present in all source FEC payload IDs and repair FEC payload IDs.

Table 8 below defines the valid values of the ffsrpts_flag field.

fec_payload_id_mode - Applied FEC payload ID mode.

Table 9 below defines the valid values of the fec_payload_id_mode field.

length_of_repair_symbol - The length of the repair symbol in bytes.

num_of_repair_symbol_per_packet - The number of repair symbols sent in one FEC repair packet when ssbg_mode 2 is used.

num_of_symbol_element_per_source_symbol - The number of symbol elements that make up a source symbol when ssbg_mode 2 is used.

fec_coding_structure - The FEC encoding structure applied to the associated FEC source flow.

Table 10 below defines the allowed values of the fec_coding_structure field.

num_of_sub_block_per_source_block - Number of divided source packet blocks constituting one source packet block in a two-stage encoding structure.

number_of_repair_flows - The number of FEC repair flows.

num_of_layer_for_LAFEC - The number of layers of media protected by a layer-aware FEC encoding scheme.

repair_flow_id - An integer identifying the repair FEC flow. Indicates the packet_id value of the MMTP packet header of the FEC repair packet. The packet_id value of the corresponding FEC repair flow is repair_flow_id.

fec_code_id_for_repair_flow - Identifier of the FEC code applied to the associated FEC repair flow.

private_flag - When set to "1", indicates that there is a private field that carries private FEC information for a specific FEC algorithm. When set to "0 ", it indicates that the private field does not exist.

Table 11 below defines the allowed values of the private_flag field.

private_field_length - The length in bytes of the private field. When private_flag = "0", the corresponding value must be set to "0" to indicate that there is no private_field.

private_field - Contains private FEC information for a specific FEC algorithm.

maximum_k_for_repair_flow - the maximum number of source symbols that make up a source symbol block.

maximum_p_for_repair_flow - Maximum number of repair symbols that make up a single repair symbol block.

The FEC protection window means the time or number of packets to which all packets belonging to the relevant FEC source packet block / FEC repair packet block are to be transmitted. Therefore, the difference between the timestamp of the last transmitted packet and the timestamp value of the first transmitted packet among the packets belonging to the related source packet block / repair packet block should not exceed the FEC protection period.

protection_window_time - indicates the maximum time difference, in milliseconds, between the first packet transmitted and the last packet transmitted among the packets belonging to the related FEC source packet block / FEC repair packet block. If the value of this field is "0 "," protection_window_size "is used.

protection_window_size - indicates the maximum number of packets between the first packet transmitted from the packet belonging to the related FEC source packet block / FEC repair packet block and the last packet transmitted. When the value of this field is "0 "," protection_window_time "is used.

As described above, the FEC scheme can operate in two different modes. The two modes may be FEC payload ID mode 0 and FEC payload ID mode 1. The FEC payload ID mode 0 is a mode for adding a source FEC payload ID to an MMTP packet, and the FEC payload ID mode 1 is a mode for not modifying the MMTP packet.

The encoding symbol of the FEC payload ID mode 1 is the same as that of the FEC payload ID mode 0. That is, the source packets (MMT packets) belonging to the source packet block are arranged in the same order as the packet_id provided for the corresponding FEC-encoded packet flow of the AL-FEC message. If the packet_id is the same, the packet_sequence_number of the MMTP packet header increases.

The source symbol block of the FEC payload ID mode 1 is the same as the source symbol block when ssbg_mode 0 and ssbg_mode 1 are used.

13 is a diagram illustrating an example of generating a source symbol block in a source packet block using ssbg_mode 2 in a communication system according to an embodiment of the present disclosure.

13, it is assumed that one source packet block is composed of, for example, five MMTP packets, and that the lengths of the five MMTP packets are 34, 30, 56, 40, and 48 bytes, respectively. The five MMTP packets may be placed in a source symbol block composed of eight source symbols. The size (T) of each of the eight source symbols will be 32. [ Each of the eight source symbols may be composed of two symbol elements (T '= T / 2 = 16 bytes).

According to the above-described assumption, one MMTP packet can be placed in one or a plurality of source symbols. For example, MMTP packet # 0 having a size of 34 bytes will be preferentially placed in two symbol elements constituting one source symbol (SS # 0) having a size of 32 bytes. The remaining 2 bytes of the MMTP packet # 0 are allocated to the first symbol element of the two symbol elements constituting the next source symbol SS # 1. In the first symbol element, the remaining 2 bytes of the MMTP packet # 0 may be allocated and the remaining bytes may be filled with padding data. The remaining four MMTP packets may be placed in the remaining source symbols using the same rule.

FEC payload ID In mode 1, the FEC source packet does not contain the source FEC payload ID, so it has the same format as the existing MMTP packet.

14 is a view showing another example of the FEC repair packet format in the broadcasting system according to the embodiment of the present disclosure.

Referring to FIG. 14, the FEC repair packet may include an MMTP packet header, a repair FEC payload ID, length repair data, and one or more repair symbols. The length repair data is optionally present, and its existence can be known through the repair FEC payload ID. The length repair data is information for protecting a length symbol composed of two octets. Each length symbol indicates the length of each packet belonging to the associated source packet block and the length of a dropped packet.

Also, if ssbg_mode0 or ssbg_mode1 is used, the FEC repair packet should contain only one repair symbol. When ssbg_mode2 is used, the FEC repair packet may contain one or more repair symbols.

Also, all the FEC repair packets except the last FEC repair packet among the FEC repair packets belonging to the FEC repair packet block must include the same number of repair symbols.

15 is a diagram showing an example of a repair FEC payload ID in a broadcasting system according to an embodiment of the present disclosure.

15, a field for providing information for each packet_id among the fields included in the repair FEC payload ID, the order of SS_start_seq_nr [i], L [i], SPB_length [i] It follows the order of packet_id. This order is also the same as the order in which the source symbols are arranged in the corresponding source symbol block.

An example of the usage of each of the fields shown in FIG. 15 is as follows.

Discontinuity_flag (D, 1 bits) - There is a discontinuity in the packet_sequence_number field value in the MMTP packet header of the FEC source packet generated by the source packets having the same packet_id included in the source packet block protected by the corresponding FEC repair packet. Respectively.

If the value is set to, for example, "0 ", there should be no interruption in the packet_sequence_number field values of source packets having the same packet_id included in the source packet block.

If the value is, for example, "1 ", then the value of the existing I field must be set to" 1 ".

T (1 bit) - Indicates the presence of a timestamp field. If the value is, for example, "0", there is no timestamp field, and if the value is, for example, "1", there is a timestamp field.

SSM (2 bits) - represents the length of the SS_start_seq_nr [i] fields that exist after. The length of the SS_start_seq_nr [i] field is "8 + 8 * SSM bits".

I (1 bit) - Indicates the presence of length repair data. If the value is set to, for example, "1", the length repair data must be present, and if the value is set to "0", for example, the length repair data should not exist. If the value of the D field is "1" or SSBG Mode 2 is used, the corresponding value must be set to "1".

FEC_parameter_flag (F, 1 bits) - Indicates whether the length repair data was generated using the same FEC code and the same parameters as the repair symbol of the FEC repair packet. For example, when the corresponding value is "0", L3, LRSB_lenght, L6, and LSB_length fields do not exist. For example, when the corresponding value is "1", L3, LRSB_lenght, L6, and LSB_length fields are present. The corresponding field must be set to "0" when the value of the I field is "0" and must be set to "1" when the value of the D field is "1".

num_LRS_flag (N, 1 bits) - Length of current FEC repair packet Indicates whether the number of length repair symbols included in repair data is equal to the number of repair symbols included in the current FEC repair packet.

If the value is set to "0", for example, the length repair data should include the same number of length repair symbols as the number of repair symbols included in the current FEC repair packet, and L5, LRS_ID, L7 and num_LRS fields Should not exist.

If the value is set to "1", for example, the length repair data may include a number of length repair symbols different from the number of repair symbols included in the current FEC repair packet, and L5, LRS_ID, L7 and num_LRS Field must exist.

The value of the corresponding field must be set to "0" when the value of the I field is "0", and must be set to "1" when the value of the F field is "1".

reserved (R: 1 bit) - Reserved for future use.

timestamp (32 bits) - indicates the timestamp field value present in the packet header of the MMTP packet transmitted first in the relevant FEC source / repair packet block.

SS_start_seq_nr [i] (8 + 8 * SSM bits) - Packet_sequence_number of packets identical to the i-th packet_id value provided in the AL-FEC message (encoded FEC flow loop) in the source packet block protected by the corresponding FEC repair packet 8 &lt; * &gt; i has values of 0, 1, ..., N-1, and N is the number of assets belonging to the coded FEC flow.

L [i] (2 bits) - indicates the length of the SPB_length [i] field located after. The length of the SPB_length [i] field is, for example, "6 + 8 * L [i]" bits.

SP_length [i] (6 + 8 * L [i] bits) - (SS_end_seq_nr [i] - SS_start_seq_nr [i] + 1). Here, SS_end_seq_nr [i] indicates that the value of the packet_id in the source packet block protected by this FEC repair packet is lower than the maximum value among the packet_sequence_number of packets identical to the i-th packet_id value provided in the AL-FEC message (encoded FEC flow loop) 8 * SSM bits.

When the value of the D field is "0 ", for example, the value of the corresponding field is i (i) in which a packet_id value in the source packet block protected by the corresponding FEC repair packet is provided in the AL-FEC message Lt; th &gt; packet_id value.

L2 (2 bits) - indicates the length of the RSB_length field located after The length of the RSB_length field is, for example, "6 + 8 * L2" bits.

RSB_length (6 + 8 * L2 bits) - indicates the number of repair symbols constituting the relevant repair symbol block.

L3 (2 bits) - indicates the length of the LRSB_length field that is located after. The length of the LRSB_length field is, for example, "6 + 8 * L3" bits. The corresponding field exists only when the value of the F field is "1 ".

LRSB_length (6 + 8 * L3 bits) - represents the number of length repair symbols constituting the associated length repair symbol block. This field exists only when the value of the F field is "1 ", for example. The fact that this field does not exist even though the value of the I field is "1 " indicates that the number of the length repair symbols constituting the length repair symbol block is equal to the number of the repair symbols constituting the repair symbol block associated with this FEC repair packet .

L4 (2 bits) - indicates the length of the SSB_length field located after. The length of the SSB_length field is, for example, "6 + 8 * L4" bits. This field exists only when SSBG Mode 2 is used.

SSB_length (6 + 8 * L4 bits) - indicates the number of source symbols constituting the associated source symbol block. This field exists only when SSBG Mode 2 is used.

L5 (2 bits) - indicates the length of the LRS_ID field located after The length of the LRS_ID field is "6 + 8 * L5" bits. This field exists only when the value of the N field is "1 ".

LRS_ID (6 + 8 * L5 bits) - Indicates an integer that can identify the first length repair symbol included in the FEC repair packet. For example, 0 for each repair symbol, given a value in the corresponding length repair symbol block. This field exists only when the value of the N field is "1 ". The fact that the corresponding field does not exist even though the value of the I field is "1 " indicates that the value of the corresponding field is the same as the value of the RS_ID field.

L6 (2 bits) - Indicates the length of the LSB_length field located after. The length of the LSB_length field is "6 + 8 * L6" bits. This field exists only when the value of the F field is "1 ".

LSB_length (6 + 8 * L6 bits) - indicates the number of length symbols constituting the association length symbol block. The corresponding field exists only when the value of the F field is "1 ". The fact that the field does not exist even though the value of the I field is "1 " indicates that the number of length symbols constituting the length symbol block is equal to the number of source symbols constituting the source symbol block associated with the FEC repair packet.

L7 (2 bits) - Indicates the length of the num_LRS field that follows. The length of the num_LRS field is, for example, "6 + 8 * L7" bits. The corresponding field exists only when the value of the N field is "1 ".

num_LRS (6 + 8 * L7 bits) - indicates the number of length-repair symbols constituting the length repair data of the corresponding FEC repair packet. This field exists only when the value of the N field is "1 ". The fact that the field does not exist even though the value of the I field is "1 " means that the value of the corresponding field is equal to the number of repair symbols included in the current FEC repair packet.

RS_ID (24 bits) - A serial number for identifying the first repair symbol included in the FEC repair packet. If the FEC repair packet includes more than two repair symbols, the serial number of the subsequent repair symbols of the first repair symbol increases by a given value, for example, by one. For example, 0 for all repair symbol blocks, and increases by a given value for each repair symbol, for example, 1. The corresponding field is transmitted in the lower 24 bits of the packet_sequence_number field of the MMTP packet header.

The FEC payload ID mode 1 described above is for an FEC operation that does not use a source FEC payload ID. It uses the repair FEC payload ID to inform the receiving device where each MMT packet (source packet) is located in the source symbol block .

When using the SSBG Mode 2 described above, the location of the source packet in the source symbol block may depend on the lengths of other source packets preceding the source packet. In addition, the value of the packet_sequence_number field of MMT packets (source packets) having the same packet_id belonging to the source packet block may have a disconnection due to an untransmitted packet. In this case, additional length repair data is required to reconstruct the source symbol block using the FEC source packet received at the receiving apparatus.

To this end, the transmitting apparatus can generate a length-repair symbol block composed of one or more length-repair symbols for protecting a length symbol block. The length symbol block is composed of length symbols, and each length symbol can have a fixed size of 2 bytes. The fixed value represents the length of the MMTP packet belonging to the "virtual source packet block ".

Let the minimum value be Smin (packet_id) and the maximum value be Smax (packet_id) among the packet_sequence_number of MMT packets having the same packet_id belonging to the source packet block. At this time, the "virtual source packet block" has a packet_sequence_number value {Smin (packet_id) +1, Smin (packet_id) +2. ... Smax (packet_id) - 1}. Untransmitted packets are not transmitted to the actual channel and are not protected by FEC. The value of the length symbol associated with a packet that has not been transmitted may be set to a predetermined value (e.g., 0).

In the above-described embodiment, the length repair symbol is generated through the same FEC code as the associated FEC repair flow. Depending on the implementation, length repair symbols may be generated using FEC codes and other FEC codes. However, in this case, other FEC codes used shall be provided to the receiving device. The value of the length symbol remaining when the number of length symbols constituting the length symbol block is larger than the number of MMT packets belonging to the associated "virtual source packet block ", can be set to a predetermined value (e.g., 0).

The num_LRS_flag field indicates whether or not the number of the length repair symbols included in the length repair data of the current FEC repair packet is the same as the number of the repair symbols included in the current FEC repair packet.

However, it should be noted that the num_LRS_flag field can be used in the following form as well as the above-mentioned form.

num_LRS_flag (N, 1 bits) - Length of the current FEC repair packet Indicates whether the length repair symbols included in the repair data have the same serial number as the repair symbols included in the current FEC repair packet.

If the value is set to, for example, "0 ", the length repair data should include the same number of length repair symbols as the number of repair symbols included in the current FEC repair packet. The identification number of each length repair symbol should be the same as the serial number of the repair symbol in the same order. Also, the L5, LRS_ID, L7, and num_LRS fields must not exist.

If the value is set to, for example, "1 ", the fields L5, LRS_ID, L7 and num_LRS must be present. This indicates that the number of the length repair symbols included in the length repair data of the current FEC repair packet and the serial number of each length repair symbol are signaled to the corresponding fields.

The value of the corresponding field must be set to "0" when the value of the I field is "0", and must be set to "1" when the value of the F field is "1". Also, for the FEC repair packets belonging to one FEC repair packet block, the value of the corresponding field must be set to the same value.

Again, this is explained as follows.

num_LRS_flag (N, 1 bits) indicates whether or not the identifier values of the length repair symbols included in the length repair data of the corresponding FEC repair packet are the same as the identifier values of the repair symbols delivered by the corresponding FEC repair packet.

For example, if the number of length repair symbols included in the length repair data is equal to the number of repair symbols included in the corresponding FEC repair packet, the value of the num_LRS_flag field may be set to "0 ". In this case, the identifier of each length repair symbol may have the same value in the same order as the identifier of the repair symbol. In this case, the repair FEC payload ID will not have the L5 field, the LRS_ID field, the L7 field, and the num_LRS field.

As another example, if the L5 field, the LRS_ID field, the L7 field, and the num_LRS field are present in the repair FEC payload ID, the value of the num_LRS_flag field may be set to "1 ". In this case, the number of the length repair symbols and the identifier value of the first length repair symbol included in the length repair data of the corresponding FEC repair packet can be explicitly provided.

Further, when the value of the I field is set to, for example, "0 ", the value of the num_LRS_flag field will be set to" 0 ". When the value of the F field is set to, for example, "1 ", the value of the num_LRS_flag field will be set to" 1 ". The value of the num_LRS_flag field will be the same for all FEC repair packets included in the corresponding FEC repair packet block.

According to one embodiment, the FEC decoder in the receiving apparatus can recover the length information of the MMT packet using the length repair data, reconstruct the related source symbol block using it, and recover the source symbol through the FEC decoding . If the length of the restored MMT packet is 0, it can be regarded as a packet that has not been transmitted.

A source symbol block including K source symbols is generated in a source packet block including K 'MMT packets (source packets) using SSBG Mode, and the source symbol block is a repair including P repair symbols Assume that a symbol block is protected. Where the length repair symbol can be generated using the same parameters as those used to protect the source symbol block. This means that the length symbol block is composed of K length symbols and the length repair symbol block is composed of P length repair symbols. At this time, the value of the first K 'length symbols is set to the MMT packet length of the related source packet block, and the value of the remaining K - K' length symbols can be set to zero.

It is a matter of course that the position of each field included in the repair FEC payload ID shown in FIG. 15 can be changed.

FIG. 16 is a diagram illustrating an example of a source symbol block generated using ssbg_mode 2 in the broadcast system according to the embodiment of the present disclosure, FIG. 17 is a diagram illustrating a length for protecting packet length information in a broadcast system according to an embodiment of the present disclosure Symbol block shown in Fig.

A transmitting apparatus according to an embodiment generates P length repair symbols and transmits them as length repair data of an FEC repair packet. In this case, the length repair symbol and the repair symbol having the same identification value can be transmitted in the same packet. In the embodiment of the repair FEC payload ID described above, LRS_ID may be omitted.

Consider a case where p number of MMT packets are not transmitted in a virtual source packet block composed of K 'MMT packets, and a source packet block composed of K' - p MMT packets is used. At this time, the value of the packet_sequence_number field of the MMT packets having the same packet_id belonging to the source packet block may have a disconnection due to the non-transmitted packet.

18 is a diagram showing an example of an encoding symbol block when a packet drop is applied in the broadcasting system according to the embodiment of the present disclosure.

Referring to FIG. 18, it can be seen that two MMT packets are not transmitted in a virtual source packet block including 10 MMT packets, so that the source packet block includes only 8 MMT packets.

FIG. 19 is a diagram showing an example of a length-encoded symbol block when a packet drop is applied in the broadcasting system according to the embodiment of the present disclosure.

Referring to FIG. 19, since the virtual source packet block includes 10 MMT packets, the length symbol block is also composed of 10 length symbols.

20 is a diagram schematically illustrating an operation procedure of a transmitting apparatus in a broadcasting system according to an embodiment of the present disclosure.

Referring to FIG. 20, in step 2010, the transmitting apparatus inputs a source packet block. The transmitting apparatus generates one or a plurality of source symbol blocks using the source packet block input in operation 2020. [ In step 2030, the transmitter performs FEC encoding on the generated source symbol blocks to generate one or a plurality of repair symbol blocks.

The transmitting apparatus determines in step 2040 whether to include the source FEC payload ID in the FEC source packet.

If it is necessary to include the source FEC payload ID in the FEC source packet, the transmitting apparatus generates one or a plurality of source FEC payload IDs in step 2080.

If it is not necessary to include the source FEC payload ID in the FEC source packet, the transmitting apparatus checks in step 2050 whether the value of the discontinuity in packet_sequence_number field is set to 1.

The packet transmitted by the transmitting apparatus may include a sequence number corresponding to the packet. The receiving apparatus can perform the rearrangement on the packet received by the sequence number. At this time, if the sequence number is disconnected, that is, if a packet having a specific sequence number is not received, the receiving apparatus needs to confirm why the packet is not received. That is, the receiving apparatus should be able to check whether a packet that has not been received is lost during transmission or a transmission is dropped by the transmitting apparatus, for example.

The value of the packet sequence number disconnection indicator field may indicate, for example, whether the disconnection of the packet sequence is due to a packet drop. In this case, the transmitting apparatus can determine that the value of the packet sequence number disconnection indicator field is set to '1'.

If the value of the packet sequence number disconnection indicator field does not need to be set to 1, the transmitting apparatus checks in step 2060 whether SSBG Mode 2 should be applied.

If the SSBG Mode 2 should be applied or the value of the packet sequence number disconnection indicator field needs to be set to 1, the transmitting apparatus generates length repair data in step 2070.

If it is necessary to generate the length repair data or to include the source FEC payload ID in the FEC source packet, the transmitting device generates one or a plurality of source FEC payload IDs in step 2080.

 It is a matter of course that the operation of the transmitting apparatus in the communication system can be variously modified from the above-described embodiment. As an example, the steps described in FIG. 20 may be over-wrapped or occur in parallel and may occur in different orders or multiple times.

As described above, information that may be required for the determination in steps 2040, 2050, and 2060 may be given as a result of operations in steps 2010, 2020, and 2030, or may be performed on a per-service or FEC And may be determined based on the transmission policy for each encoded packet flow.

It should be noted that although not shown in FIG. 20, the transmitting apparatus may include a process of generating a repair FEC payload ID.

FIG. 21 is a diagram schematically illustrating an operation procedure of a receiving apparatus in a broadcasting system according to an embodiment of the present disclosure.

21, the receiving apparatus detects that the MMTP session is started in step 2110, and receives an AL-FEC message from the transmitting apparatus in step 2120. [ The AL-FEC message may include packet_ids, ssgb_mode, and fec_payload_id_mode. The AL-FEC message has been described in detail in the foregoing, and a detailed description thereof will be omitted here.

The receiving apparatus can obtain the FEC source packet and the FEC repair packet based on the AL-FEC message received in step 2130. [ The receiving apparatus checks whether the FEC repair packet acquired in step 2140 includes the source FEC payload ID. If the source FEC payload ID exists, the receiving apparatus performs an AL-FEC decoding operation in step 2180 to recover the missing MMT packet.

If the source FEC payload ID does not exist, the receiving apparatus checks in step 2150 whether the value of the Discontinuity in packet_sequence_number field is set to 1 from the repair FEC payload ID of the FEC repair packet. If the value of the Discontinuity in Packet_sequence_number field is set to 1, the receiving apparatus performs an AL-FEC decoding operation in step 2170 to recover the length repair data. The receiving apparatus performs an AL-FEC decoding operation in step 2180 to recover the missing MMT packets.

If the value of the Discontinuity in Packet_sequence_number field is not set to 1, the receiving apparatus checks in step 2160 whether SSBG Mode 2 is applied. If the SSBG Mode 2 is not applied, the receiving apparatus performs an AL-FEC decoding operation in step 2180 to recover the missing MMT packets.

When the SSBG Mode 2 is applied, the receiving apparatus performs AL-FEC decoding operation in step 2170 to recover length repair data, and performs AL-FEC decoding operation in step 2180 to recover missing MMT packets.

Although FIG. 21 shows the operation of the receiving apparatus in the broadcasting system according to the embodiment of the present disclosure, various modifications may be made to FIG. In one example, although the sequential steps are shown in FIG. 21, it is understood that the steps described in FIG. 21 may occur over-wrap or in parallel, occur in a different order, or occur multiple times.

In the embodiment of the repair FEC payload ID described above, the D field is used to directly signal to the receiver whether the packet_sequence_number of the MMT packets having the same packet_id is disconnected. It is possible to determine that packets have not been transmitted for a certain value (for example, 0) after restoring the length of the packets using the length repair data in the receiving apparatus without directly signaling the disconnection of the packet_sequence_number.

22 is a diagram schematically showing the internal structure of a transmitting apparatus in a broadcasting system according to an embodiment of the present disclosure.

22, the transmitting apparatus 2200 includes a transmitter 2211, a processor 2213, a receiver 2215, and a storage unit 2217.

First, the processor 2213 controls the overall operation of the transmitting apparatus 2200, and in particular, controls operations related to the operation of transmitting / receiving signals in the broadcasting system. The operation related to the operation of transmitting / receiving a signal in the broadcasting system is the same as that described with reference to FIG. 1 to FIG. 21, and a detailed description thereof will be omitted here.

The transmitter 2211 transmits various signals and various messages to other devices included in the broadcasting system under the control of the processor 2213. Various signals and various messages transmitted by the transmitter 2211 are the same as those described with reference to FIG. 1 to FIG. 21, and a detailed description thereof will be omitted here.

The receiver 2215 receives various signals and various messages from other devices included in the broadcasting system under the control of the processor 2213. Various signals and various messages received by the receiver 2215 are the same as those described with reference to FIG. 1 to FIG. 21, and a detailed description thereof will be omitted here.

The storage unit 2217 stores programs and various data related to an operation related to an operation of transmitting and receiving a signal performed by the transmitting apparatus 2200 under the control of the processor 2213.

The storage unit 2217 stores various signals and various messages received by the receiver 2215 from the other devices.

22 shows a case where the transmitting apparatus 2200 is implemented as separate units such as a transmitter 2211, a processor 2213, a receiver 2215, and a storage unit 2217. However, it is needless to say that the transmitting apparatus 2200 can be implemented in an integrated form of at least two of the transmitter 2211, the processor 2213, the receiver 2215, and the storage unit 2217.

In addition, the processor 2213 of the transmitting apparatus 2200 may be implemented with at least one processor.

23 is a view schematically showing an internal structure of a receiving apparatus in a broadcasting system according to an embodiment of the present disclosure.

23, the receiving apparatus 2300 includes a transmitter 2311, a processor 2313, a receiver 2315, and a storage unit 2317.

The processor 2313 controls the overall operation of the receiving apparatus 2300, and particularly controls operations related to transmitting / receiving signals in the broadcasting system. The operation related to the operation of transmitting / receiving a signal in the broadcasting system is the same as that described with reference to FIG. 1 to FIG. 21, and a detailed description thereof will be omitted here.

The transmitter 2311 transmits various signals and various messages to other devices included in the broadcasting system under the control of the processor 2313. Various signals and various messages transmitted by the transmitter 2311 are the same as those described with reference to FIG. 1 to FIG. 21, and a detailed description thereof will be omitted here.

The receiver 2315 receives various signals and various messages from other apparatuses included in the broadcasting system under the control of the processor 2313. Various signals and various messages received by the receiver 2315 are the same as those described with reference to FIG. 1 to FIG. 21, and a detailed description thereof will be omitted here.

The storage unit 2317 stores programs and various data related to an operation related to an operation of transmitting and receiving a signal performed by the receiving apparatus 2300 under the control of the processor 2313. [ The storage unit 2317 stores various signals and various messages received by the receiver 2315 from the other devices.

23 shows a case where the receiving apparatus 2300 is implemented as separate units such as a transmitter 2311, a processor 2313, a receiver 2315, and a storage unit 2317. [ However, it is needless to say that the receiving apparatus 2300 can be implemented by integrating at least two of the transmitter 2311, the processor 2313, the receiver 2315, and the storage unit 2317.

Of course, the processor 2313 of the receiving apparatus 2300 may be implemented by at least one processor.

Certain aspects of the present disclosure may also be implemented as computer readable code in a computer readable recording medium. The computer readable recording medium is any data storage device capable of storing data that can be read by a computer system. Examples of the computer-readable recording medium include a read-only memory (ROM), a random-access memory (RAM), CD-ROMs, magnetic tapes , Floppy disks, optical data storage devices, and carrier waves (such as data transmission over the Internet). The computer readable recording medium may also be distributed over networked computer systems, and thus the computer readable code is stored and executed in a distributed manner. In addition, functional programs, code, and code segments for accomplishing the present disclosure may be readily interpreted by those skilled in the art to which this disclosure applies.

It will also be appreciated that the apparatus and method according to one embodiment of the present disclosure may be implemented in hardware, software, or a combination of hardware and software. Such arbitrary software may be, for example, a volatile or non-volatile storage such as a storage device such as a ROM or the like, such as, for example, a RAM, a memory chip, a device or an integrated circuit Memory, or a storage medium readable by a machine (e.g., a computer) as well as being optically or magnetically recordable, such as, for example, a CD, DVD, magnetic disk or magnetic tape. A method according to one embodiment of the present disclosure may be implemented by a computer or a mobile terminal including at least one processor and a memory and the memory may store programs or programs containing instructions embodying the embodiments of the present disclosure It will be appreciated that this is an example of a machine-readable storage medium suitable for the following.

Accordingly, this disclosure includes a program including code for implementing the apparatus or method described in any claim herein, and a storage medium readable by a machine (such as a computer) for storing such a program. In addition, such a program may be electronically transported through any medium, such as a communication signal carried over a wired or wireless connection, and this disclosure suitably includes equivalents thereof

Also, an apparatus according to an embodiment of the present disclosure may receive and store the program from a program providing apparatus connected by wire or wireless. The program providing apparatus may further include a memory for storing a program including instructions for causing the program processing apparatus to perform a predetermined content protection method, information necessary for the content protection method, and the like, and a wired or wireless communication with the graphics processing apparatus And at least one processor for transmitting the program to the transceiver upon request or automatically by the graphic processing apparatus.

While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments. Therefore, the scope of the present disclosure should not be limited to the embodiments described, but should be determined by the scope of the appended claims, as well as the appended claims.

Claims (20)

1. A method of generating a transmission packet in a broadcasting system,

   Generating a source symbol block having a plurality of source symbols using a source packet block having a plurality of source packets by a generation mode of one of a plurality of generation modes (ssbg_mode # 0, # 1, # 2)

   A step of generating a repair symbol block for the generated source symbol block by one FEC scheme among a plurality of forward error correction (FEC) methods (FEC payload ID mode 0 and FEC payload ID mode 1) ,

   Generating a source packet by the plurality of source packets;

   And generating a repair packet based on the generated repair symbol block,

   Here, the process of generating the repair packet may include:

   A first FEC scheme (FEC payload ID mode 1) is applied to generate the repair symbol block, and in response to the occurrence of the disconnection of the packet sequence number, the repair message includes the length repair data and the repair FEC payload identifier And generating a packet.
2. The method according to claim 1,

   Wherein a value of a discontinuity flag (D) of the repair FEC payload identifier (ID) is set to indicate that a disconnection of the packet sequence number occurs in response to the disconnection of the packet sequence number,

   (I) value of the repair FEC payload identifier (ID) is set to indicate that a disconnection of the packet sequence number has occurred, the value of the second flag (I) of the repair FEC payload identifier The packet is set to indicate that the length repair data is included in the packet.
3. 3. The method of claim 2,

   The value of the third flag (F: FEC_parameter_flag) of the repair FEC payload identifier (ID) is calculated by taking into consideration the value of the first flag (D) and the value of the second flag (I) And to indicate whether the same FEC code is used for the generation of the data.
4. The method of claim 3,

   The value of the fourth flag (N: num_LRS_flag) of the repair FEC payload identifier (ID) is set to a value of the repair flag included in the length repair data in consideration of the value of the second flag (I) The number of repair symbols included in the repair packet is equal to the number of repair symbols included in the repair packet.
5. The method of claim 1, wherein the step of generating the repair packet comprises:

   Wherein the first FEC scheme (FEC payload ID mode 1) is applied to generate the repair symbol block, and in response to applying the second generation mode (ssbg_mode # 2) to generate the source symbol block, And generating the repair packet so as to include the repair FEC payload identifier (ID)

   In response to the application of the second generation mode (ssbg_mode # 2) to generate the source symbol block, the second flag (I) value of the repair FEC payload identifier (ID) is stored in the repair packet as the length repair data Is included. &Lt; / RTI &gt;
6. 6. The method of claim 5,

   The value of the third flag (F: FEC_parameter_flag) of the repair FEC payload identifier (ID) may be the same as the value of the second flag (I) for the generation of the repair symbol block and the generation of the length repair data Is set to indicate that the user has been used.
7. The method according to claim 6,

   The value of the fourth flag (N: num_LRS_flag) of the repair FEC payload identifier (ID) is set to a value of the repair flag included in the length repair data in consideration of the value of the second flag (I) The number of repair symbols included in the repair packet is equal to the number of repair symbols included in the repair packet.
8. 8. The method according to claim 4 or 7,

   Wherein the repair FEC payload identifier (ID) further includes information on a length set in consideration of the first to fourth flags.
9. A transmitting apparatus of a broadcasting system,

   A transmitter for transmitting a transmission packet to an external device for broadcasting service; And

   A processor coupled to the transmitter for generating the transport packet for the broadcast service,

   Wherein the at least one processor comprises:

   A source symbol block having a plurality of source symbols is generated using a source packet block having a plurality of source packets by a generation mode of one of a plurality of generation modes (ssbg_mode # 0, # 1, # 2)

   A repair symbol block for the generated source symbol block is generated by one FEC scheme among a plurality of forward error correction (FEC) methods (FEC payload ID mode 0 and FEC payload ID mode 1)

   Generating a source packet by the plurality of source packets,

   A first FEC scheme (FEC payload ID mode 1) is applied to generate the repair symbol block, and in response to the occurrence of the disconnection of the packet sequence number, the repair message includes the length repair data and the repair FEC payload identifier A transmitting device for generating a packet.
10. 10. The apparatus of claim 9, wherein the at least one processor comprises:

    (D) a discontinuity flag (D) of the repair FEC payload identifier (ID) in response to the disconnection of the packet sequence number indicating that a disconnection of the packet sequence number has occurred,

    (I) value of the repair FEC payload identifier (ID) in response to being set to indicate that a disconnection of the packet sequence number has occurred, And the packet is set to indicate that the length repair data is included in the packet.
11. 11. The apparatus of claim 10, wherein the at least one processor is configured to:

    The generation of the repair symbol block and the repair of the length of the repair symbol block are performed by considering the value of the third flag (F: FEC_parameter_flag) of the repair FEC payload identifier (ID) And to indicate whether the same FEC code is used for the generation of the data.
12. 12. The system of claim 11, wherein the at least one processor comprises:

    (N: num_LRS_flag) value of the repair FEC payload identifier (ID) in consideration of the value of the second flag (I) and the value of the third flag (F) The number of repair symbols included in the repair packet is equal to the number of repair symbols included in the repair packet.
13. 10. The apparatus of claim 9, wherein the at least one processor comprises:

    Wherein the first FEC scheme (FEC payload ID mode 1) is applied to generate the repair symbol block, and in response to applying the second generation mode (ssbg_mode # 2) to generate the source symbol block, And the repair FEC payload identifier (ID)

    (I) value of the repair FEC payload identifier (ID) to the repair packet in response to the application of the second generation mode (ssbg_mode # 2) to generate the source symbol block, And the transmission information is set to indicate that the information is included.
14. 14. The apparatus of claim 13, wherein the at least one processor comprises:

    The same FEC code is used for generation of the repair symbol block and generation of the length repair data taking the value of the second flag (I) into consideration as the third flag (F: FEC_parameter_flag) value of the repair FEC payload identifier (ID) And said transmission means is configured to indicate whether or not it is used.
15. 15. The system of claim 14, wherein the at least one processor comprises:

    The value of the fourth flag (N: num_LRS_flag) of the repair FEC payload identifier (ID) is set to a value of the repair flag included in the length repair data in consideration of the value of the second flag (I) The number of repair symbols included in the repair packet is equal to the number of repair symbols included in the repair packet.
16. 16. The method according to claim 12 or 15,

    Wherein the repair FEC payload identifier (ID) further includes information on a length set in consideration of the first to fourth flags.
17. A method for a receiving apparatus to recover a transmission packet in a broadcasting system,

    Receiving a source packet including a plurality of source packets and a repair packet including a repair symbol block,

    (FEC payload ID mode 0, FEC) to generate the repair symbol block based on a plurality of flags included in a repair forward error correction (FEC) payload identifier (ID) of the repair packet. (FEC payload ID mode 1) among the FEC payload ID mode 1) and identifying whether a packet sequence number is disconnected;

    Decoding the length repair data of the repair packet in response to the first FEC scheme (FEC payload ID mode 1) is applied and the packet sequence number is disconnected;

    And recovering the missing transmission packet using the decoded length repair data,

    The plurality of flags may include a first flag (D) indicating discontinuation of the packet sequence number, a second flag (I) indicating that the repair packet includes the length repair data, A third flag (F: FEC_parameter_flag) indicating whether the same FEC code is used for generation of the repair symbol block and generation of the length repair data, and the number of repair symbols included in the length repair data, And a fourth flag (N: num_LRS_flag) indicating that the number of repair symbols included is the same,

    Wherein the repair FEC payload identifier (ID) further includes information on a length set in consideration of the first to fourth flags.
18. 18. The method of claim 17,

    The first FEC scheme (FEC payload ID mode 1) is applied to generate the repair symbol block, and the plurality of generation modes (ssbg_mode # 0, # 1, # 2) for generating the source symbol block using the source packet block, 2) is applied to the source packet, determining whether a second generation mode (ssbg_mode # 2)

    And decoding the length repair data of the repair packet in response to applying the first FEC scheme (FEC payload ID mode 1) and the second generation mode (ssbg_mode # 2).
19. A receiving apparatus of a broadcast system,

    A receiver for receiving a source packet including a plurality of source packets and a repair packet including a repair symbol block; And

    And a processor coupled to the receiver for recovering a source packet received via the receiver,

    Wherein the at least one processor comprises:

    (FEC payload ID mode 0, FEC) to generate the repair symbol block based on a plurality of flags included in a repair forward error correction (FEC) payload identifier (ID) of the repair packet. The first FEC scheme (FEC payload ID mode 1) of the FEC payload ID mode 1) is applied to identify whether the packet sequence number is disconnected,

    Wherein the first FEC scheme (FEC payload ID mode 1) is applied, the length repair data of the repair packet is decoded in response to the disconnection of the packet sequence number,

    Recovering a missing transmission packet using the decoded length repair data,

    The plurality of flags may include a first flag (D) indicating discontinuation of the packet sequence number, a second flag (I) indicating that the repair packet includes the length repair data, A third flag (F: FEC_parameter_flag) indicating whether the same FEC code is used for generation of the repair symbol block and generation of the length repair data, and the number of repair symbols included in the length repair data, And a fourth flag (N: num_LRS_flag) indicating that the number of repair symbols included is the same,

    Wherein the repair FEC payload identifier (ID) further includes information on a length set in consideration of the first to fourth flags.
20. 20. The apparatus of claim 19, wherein the at least one processor comprises:

    The first FEC scheme (FEC payload ID mode 1) is applied to generate the repair symbol block, and the plurality of generation modes (ssbg_mode # 0, # 1, # 2) for generating the source symbol block using the source packet block, 2) is applied for the source packet, and if the second generation mode (ssbg_mode # 2)

    And decodes the length repair data of the repair packet in response to the application of the first FEC scheme (FEC payload ID mode 1) and the second generation mode (ssbg_mode # 2).

Images