Re-multiplexing device and program

Abstract

To provide a re-multiplexing device that suppresses a decrease in transmission efficiency and the occurrence of jitter and is compatible with the TDM system.SOLUTION: A re-multiplexing unit 100 includes: a TLV packetizing unit 103 that encapsulates, for each layer, a data signal of the layer to generate a TLV packet; a pseudo-FEC block constitution unit 104 that constitutes, for each layer, a pseudo-FEC block constituted of a header area, a main signal area in which the TLV packets of the layer are stored, and a BCH parity area; a pseudo-multiplex frame constitution unit 105 that constitutes, for each layer, a pseudo-multiplex frame by concatenating the pseudo-FEC blocks of the layer; an MMI packetizing unit 106 that generates, for each layer, an MMI packet obtained by adding a header including control information corresponding to a TDM method to data units obtained by dividing the pseudo-multiplex frame of the layer into fixed-length data units; and a packet sending unit 109 that multiplexes the MMI packets of each of the multiple layers and outputs them at a constant rate.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a remultiplexing device and a program. [Background technology]

[0002] As the next-generation terrestrial digital broadcasting system, development is underway on an advanced terrestrial broadcasting system (hereinafter referred to as the "advanced system") that will improve frequency utilization efficiency compared to the current terrestrial digital broadcasting system, ISDB-T (Integrated Services Digital Broadcasting-Terrestrial).The advanced system will support IP (Internet Protocol) as a multiplexing format and will also support hierarchical transmission technology, which remultiplexes multiple programs with different transmission tolerances and transmission capacities, such as for mobile and fixed reception, and transmits them on a single modulated wave.

[0003] In current terrestrial broadcasting, multiple program programs, each consisting of multiplexed video, audio, and data, are remultiplexed into one by a remultiplexing device and transmitted to a transmitting station in the form of a program transmission signal to which synchronization control information necessary for modulation is added. A similar mechanism is being considered for the advanced system, in which a program transmission signal generated by a remultiplexing device in a broadcasting station is transmitted to the transmitting station via the broadcaster's private wireless line (Studio to Transmitter Link (STL) / Transmitter to Transmitter Link (TTL)) or a commercial wired IP line. The fixed-length, fixed-rate XMI (eXtensible Modulator Interface) (see, for example, Patent Document 1) and the variable-length, variable-rate STLP (Studio to Transmitter Link Protocol) have been developed as program transmission signals transmitted to the transmitting station. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-071760 Summary of the Invention [Problem to be solved by the invention]

[0005] Until now, development has been carried out assuming the use of frequency division multiplexing (FDM), which divides the frequency of Orthogonal Frequency Division Multiplexing (OFDM) frames, as a hierarchical transmission technology. However, in the method recommended as "Technical Conditions for Broadcasting Systems" by the Information and Communications Technology Subcommittee of the Ministry of Internal Affairs and Communications' Information and Communications Council in July 2023, the OFDM frame structure has been revised, making it possible to apply time division multiplexing (TDM), which divides the time of OFDM frames, as a hierarchical transmission technology.

[0006] XMI has the advantage of being easy to process because it is fixed length and fixed rate, but the disadvantage is that it transmits LDPC (Low-Density Parity-Check) parity, which means that more data other than actual data such as video and audio is transmitted, reducing transmission efficiency. STLP does not transmit LDPC parity, which prevents a decrease in transmission efficiency and has the advantage of low processing delays in the remultiplexer, but it has the disadvantage of being variable length and variable rate, which makes it difficult to transmit program transmission signals between the studio and transmitting station when signals are sent in bursts, resulting in large jitter.

[0007] XMI and STLP are program transmission signals compatible with the FDM system, but no program transmission signals compatible with the TDM system currently exist. Therefore, there is a need to develop a program transmission signal that is compatible with the TDM system while suppressing the decline in transmission efficiency and the generation of jitter.

[0008] An object of the present invention is to solve the above-mentioned problems and to provide a remultiplexing device and program that can suppress a decrease in transmission efficiency and the occurrence of jitter, and can generate a program transmission signal compatible with the TDM system. [Means for solving the problem]

[0009] (1) A remultiplexing device according to the present disclosure remultiplexes data signals of multiple layers, each having different transmission capacities and delay tolerances, to a modulation device that configures a time-division OFDM frame in which the data signals are each assigned to a plurality of time-divided subframes, and outputs the remultiplexed data signals to the modulation device. The remultiplexing device includes: a TLV packetization unit that encapsulates the data signals of each layer to generate a TLV packet for each layer; a pseudo-FEC block configuration unit that configures, for each layer, a pseudo-FEC block configured of a header area, a main signal area in which the TLV packets of that layer are stored, and a BCH parity area; a pseudo-multiplex frame configuration unit that configures, for each layer, a pseudo-multiplex frame corresponding to one OFDM frame by concatenating the pseudo-FEC blocks of that layer; an MMI packetization unit that divides the pseudo-multiplex frame of that layer into fixed-length data units and generates MMI packets by adding headers to the data units that include control information corresponding to the time division method; and a packet transmission unit that multiplexes the MMI packets of each of the multiple layers and outputs the MMI packets to the modulation device at a constant rate.

[0010] (2) In the remultiplexing device described in (1), the MMI packetization unit includes, as the control information, information indicating the subframe that transmits the data signal of the layer in the header that is added to the data unit for each layer.

[0011] (3) In the remultiplexing device described in (2), one subframe is frequency-divided into multiple layers, and the MMI packetization unit includes, as the control information, information indicating the subframe that transmits the data signal of the layer and the layer in the subframe in the header that is added to the data unit for each layer.

[0012] (4) A program according to the present disclosure causes a computer to function as a remultiplexing device according to any one of (1) to (3). [Effects of the Invention]

[0013] According to the remultiplexing device and program of the present disclosure, it is possible to suppress a decrease in transmission efficiency and the occurrence of jitter, and to generate a program transmission signal compatible with the TDM system. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a diagram illustrating an example of a configuration of a broadcasting system according to an embodiment of the present disclosure. [Figure 2] 2 is a diagram illustrating an example of the configuration of a remultiplexing unit illustrated in FIG. 1. FIG. [Figure 3A] FIG. 1 is a diagram illustrating the configuration of an FEC block. [Figure 3B] 3 is a diagram showing the configuration of a pseudo-FEC block configured by the pseudo-FEC block configuration unit shown in FIG. 2. FIG. [Figure 4] 3 is a diagram showing the configuration of an MMI packet generated by an MMI packetizing unit shown in FIG. 2. FIG. [Figure 5] FIG. 5 is a diagram illustrating the configuration of an MMI header shown in FIG. [Figure 6A] FIG. 1 is a diagram illustrating an example of the configuration of an OFDM frame. [Figure 6B] FIG. 10 is a diagram illustrating another example of the configuration of an OFDM frame. [Figure 6C] FIG. 10 is a diagram illustrating yet another example of the configuration of an OFDM frame. [Figure 7] 6 is a diagram showing an example of bit allocation for the data unit types shown in FIG. 5. FIG. [Figure 8] FIG. 10 is a diagram showing the configuration of synchronization control information. [Figure 9] 3 is a diagram for explaining the configuration of an MMI packet by a remultiplexing unit shown in FIG. 2.

[0023] FIG. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0016] Fig. 1 is a diagram illustrating an example configuration of a broadcasting system 1 according to an embodiment of the present disclosure. The broadcasting system 1 illustrated in Fig. 1 transmits a program transmission signal from a performance studio 2 to a transmission studio 3, where an OFDM frame is constructed and transmitted via a transmission antenna 4. The following describes, as an example, a case in which the current terrestrial digital broadcasting system (hereinafter referred to as the "current system") and an advanced system are applied. The following also describes, as an example, a case in which a TDM system is applied as a hierarchical transmission technology, in which data signals of multiple layers with different transmission capacities and delay tolerances are each assigned to multiple subframes obtained by time-dividing an OFDM frame.

[0017] As shown in FIG. 1, the performance venue 2 is provided with a control terminal 21, a storage unit 22, an advanced system transmission system 23, a current system transmission system 24, and a transmission unit 25.

[0018] The control terminal 21 outputs control information related to the transmission of advanced broadcast waves to the advanced broadcast transmission system 23.

[0019] The storage unit 22 stores data signals in which video, audio, subtitles, etc. are multiplexed at multiple layers with different transmission capacities and delay tolerances, and outputs the data signals to the advanced transmission system 23. The storage unit 22 outputs packets (MMTP packets) in which the data signals at each layer have been packetized in a predetermined format (for example, MMTP (MPEG Media Transport Protocol)), and IP packetized the packets (MMTP / IP packets) to the advanced transmission system 23.

[0020] The advanced transmission system 23 remultiplexes data signals of multiple layers transmitted in the advanced system, adds synchronization control information, and outputs the remultiplexed signals as program transmission signals to the transmission unit 25. The advanced transmission system 23 packetizes the data signals and synchronization control information into a predetermined format and outputs the packetized signals to the transmission unit 25. Hereinafter, the packets output by the advanced transmission system 23 are referred to as MMI (MMTP for Modulator Interface) packets. As shown in FIG. 1, the advanced transmission system 23 includes an emergency information generation unit 231, an EPG generation unit 232, a selection / multiplexing unit 233, and a remultiplexing unit 100 as a remultiplexing device according to the present disclosure.

[0021] The emergency information generating unit 231 generates emergency information such as an emergency earthquake alert and outputs it to the selecting and multiplexing unit 233. The EPG generating unit 232 generates an electronic program guide (EPG) and outputs it to the selecting and multiplexing unit 233.

[0022] The selection / multiplexing unit 233 acquires data signals (MMT / IP packets) of each layer from the memory unit 22 in accordance with the control information output from the control terminal 21, multiplexes the emergency information output from the emergency information generation unit 231 and the EPG output from the EPG generation unit 232 onto the acquired data signals, and outputs the multiplexed signals to the re-multiplexing unit 100.

[0023] Re-multiplexing section 100 re-multiplexes the data signals of multiple layers output from selection / multiplexing section 233, and outputs the result as an MMI packet to transmission section 25. Details of re-multiplexing section 100 and the MMI packet will be described later.

[0024] The current system transmission system 24 includes a remultiplexer 241. Data signals (TS: Transport Stream) of multiple layers transmitted in the current system are input to the remultiplexer 241. The remultiplexer 241 remultiplexes the input data signals of multiple layers into one TS (broadcast TS) and outputs the same to the transmitter 25.

[0025] The transmitting unit 25 transmits the MMI packets output from the advanced system transmission system 23 and the broadcast TS output from the current system transmission system 24 to the transmitting station 3 via, for example, an STL.

[0026] The transmitting station 3 is provided with a receiving section 31, an advanced standard modulator 32, an advanced standard transmitter 33, a current standard modulator 34, and a current standard transmitter 35.

[0027] The receiving unit 31 receives the MMI packets and broadcast TS transmitted from the performance studio 2. The receiving unit 31 outputs the received MMI packets to the advanced standard modulation device 32, and outputs the received broadcast TS to the current standard modulation device 34.

[0028] Based on the MMI packet output from the receiver 31, the advanced modulation device 32 constructs a time-division OFDM frame in which data signals of multiple layers are each assigned to multiple time-divided subframes, and outputs the frame to the advanced transmitter 33.

[0029] The advanced-standard transmitter 33 transmits the OFDM frame output from the advanced-standard modulator 32 via the transmission antenna 4 .

[0030] Based on the broadcast TS output from the receiving unit 31, the current system modulation device 34 constructs a time-division OFDM frame in which multiple layer data signals are each assigned to multiple time-divided subframes, and outputs the frame to the current system transmitter 35.

[0031] The current system transmitter 35 transmits the OFDM frame output from the current system modulation device 34 via the transmission antenna 4 .

[0032] Next, a description will be given of the configuration of the remultiplexing section 100 as a remultiplexing device according to the present disclosure. Fig. 2 is a diagram showing an example of the configuration of the remultiplexing section 100 according to the present embodiment.

[0033] 2, the remultiplexing unit 100 according to this embodiment includes a packet filter 101, an IP header compression unit 102, a TLV packetization unit 103, a pseudo-FEC block construction unit 104, a pseudo-multiplex frame construction unit 105, an MMI packetization unit 106, a synchronization control MMI packet construction unit 107, a stuff MMI packet construction unit 108, and a packet transmission unit 109. The packet filter 101, the IP header compression unit 102, the TLV packetization unit 103, the pseudo-FEC block construction unit 104, the pseudo-multiplex frame construction unit 105, and the MMI packetization unit 106 are provided corresponding to each of a plurality of layers with different transmission capacities and delay tolerances that are transmitted in the advanced system.

[0034] A data signal (MMTP / IP packet) of the corresponding layer is input to the packet filter 101. The packet filter 101 selects (packet filters) a packet to be transmitted based on the source IP address, destination IP address, protocol type, source port number, destination port number in the UDP header, etc. of the input MMTP / IP packet, and outputs the selected MMTP / IP packet to the IP header compression unit 102.

[0035] The IP header compression unit 102 compresses the IP header of the MMTP / IP packet output from the packet filter 101 as necessary, and outputs the result to the TLV packetization unit 103 .

[0036] The TLV packetizer 103 receives signaling information (SI) (TLV-SI) in TLV format. The SI defines, for example, a terrestrial distribution system descriptor that indicates the physical conditions of a terrestrial transmission path. The TLV packetizer 103 encapsulates the received TLV-SI and the MMT / IP packet output from the IP header compressor 102 into a TLV packet to generate a TLV packet. The TLV packetizer 103 outputs the generated TLV packet to the pseudo-FEC block constructor 104. That is, the TLV packetizer 103 encapsulates the data signal of each layer into a TLV packet for each layer to generate a TLV packet.

[0037] The pseudo FEC block constructing unit 104 constructs a pseudo FEC (Forward Error Correction) block from the TLV packets output from the TLV packetizing unit 103 .

[0038] In XMI, FEC blocks are generated from TLV packets at regular intervals. Figure 3A shows the structure of an FEC block. As shown in Figure 3A, an FEC block consists of an FEC block header area, a main signal area, a BCH parity area, and an LDPC parity area.

[0039] The main signal area stores TLV packets. The FEC block header area stores information indicating the beginning position of the first TLV packet stored in the main signal area, specifically the position of the first byte of the first TLV packet stored in the FEC block, as the number of bytes from the beginning of the FEC block excluding the FEC block header. The BCH parity area and LDPC parity area store the bit "1".

[0040] The size of the FEC block is set to two sizes depending on the code length (Short or Normal) of the LDPC coding. The sizes of the main signal area, BCH parity area, and LDPC parity area are determined according to the coding rate. For example, when the coding rate is 7 / 16 and the code length is Normal, the size of the FEC block is 8640 bytes (FEC block header area: 2 bytes, main signal area: 3754 bytes, BCH parity area: 24 bytes, LDPC parity area: 4860 bytes).

[0041] The pseudo-FEC block constructing unit 104 generates a pseudo-FEC block from a signal block obtained by excluding the LDPC parity area from the FEC block described with reference to Fig. 3A. That is, as shown in Fig. 3B, the pseudo-FEC block constructing unit 104 constructs a pseudo-FEC block for each layer, which is composed of a header area (FEC block header area), a main signal area storing the TLV packet of the layer, and a BCH parity area.

[0042] Referring back to FIG. 2, the pseudo-FEC block constructor 104 outputs the constructed pseudo-FEC block to the pseudo-multiplex frame constructor 105 .

[0043] The pseudo multiplex frame constructing unit 105 sequentially concatenates the pseudo FEC blocks output from the pseudo FEC block constructing unit 104 to construct a multiplex frame (hereinafter referred to as a "pseudo multiplex frame") corresponding to one OFDM frame. That is, the pseudo multiplex frame constructing unit 105 constructs a pseudo multiplex frame corresponding to one OFDM frame by concatenating the pseudo FEC blocks of each layer for each layer. The pseudo multiplex frame constructing unit 105 outputs the constructed pseudo multiplex frame to the MMI packetizing unit 106.

[0044] The MMI packetizer 106 divides the pseudo-multiplex frame output from the pseudo-multiplex frame constructor 105 into data units of a fixed length (for example, 1080 bytes). Then, the MMI packetizer 106 generates MMI packets by adding headers corresponding to IP, UDP, MMTP, and MMI to the data units. The header corresponding to MMI is a header that includes control information corresponding to the TDM method. For example, as shown in FIG. 4, the MMI packetizer 106 constructs an MMI packet by adding an IPv4 header (20 bytes), a UDP header (8 bytes), an MMTP header (12 bytes), and an MMI header (7 bytes) to the data units. That is, the MMI packetizer 106 divides the pseudo-multiplex frame of each layer into fixed-length data units for each layer, and generates MMI packets by adding a header (MMI header) that includes control information corresponding to the TDM method to the data units. Because the data units and the headers added to the data units each have a fixed length, the MMI packets are fixed-length.

[0045] Referring back to FIG. 2, MMI packetization section 106 outputs the generated MMI packets to packet transmission section 109.

[0046] The synchronization control MMI packet construction unit 107 constructs an MMI packet (synchronization control MMI packet) that stores synchronization control information indicating information related to transmission control, such as transmission parameters for constructing an OFDM frame, the timing of transmitting the OFDM frame, and TMCC (Transmission and Multiplexing Configuration Control) information, in place of a data unit, and outputs the MMI packet to the packet sending unit 109.

[0047] The stuff MMI packet constructing unit 108 constructs an MMI packet (stuff MMI packet) in which stuff bits of the same size as the data units are stored instead of the data units, and outputs the MMI packet to the packet sending unit 109. The stuff MMI packet is used to keep the number of MMI packets output per second by the remultiplexing unit 100 constant even when the modulation method or coding rate is different.

[0048] The packet sending unit 109 multiplexes the MMI packets for each of the multiple layers and outputs them to the transmitting station 3 (advanced modulation device 32) at a constant rate. Specifically, the packet sending unit 109 outputs one synchronization control MMI packet at the beginning of the OFDM frame, followed by the MMI packets for each layer. After all the MMI packets for each layer have been output, the packet sending unit 109 outputs stuff MMI packets so that the number of MMI packets that make up the OFDM frame remains constant.

[0049] Fig. 5 is a diagram showing the configuration of the MMI header shown in Fig. 4. As shown in Fig. 5, the MMI header includes a frame number (16 bits), a data unit type (8 bits), a sequence number (16 bits), and a data unit length (16 bits).

[0050] The frame number indicates the frame number to which the data unit or synchronization control information included in the MMI packet belongs. The frame number is a value that starts from 0 and goes up to 65535, and returns to 0 when it reaches 65535.

[0051] The data unit type indicates the type of payload after the MMI header of the MMI packet. The advanced system is expected to use an FDM system in which the portion after the frame synchronization signal and TMCC signal at the beginning of the OFDM frame is frequency-divided into multiple layers, as shown in Figure 6A, and an FDM system in which the portion after the frame synchronization signal and TMCC signal at the beginning of the OFDM frame is time-divided into multiple subframes, as shown in Figure 6B. It is also expected that one subframe will be frequency-divided into multiple layers, or one layer will be frequency-divided into multiple sublayers, as shown in Figure 6C.

[0052] The data unit type indicates the type of payload of the MMI packet (whether it is synchronization control information or a data unit), and if the payload is a data unit, the number of the subframe (subframe number) in which the MMI packet is transmitted, the number of the layer (layer number) in which the MMI packet is transmitted, and the number of the sub-layer (sub-layer number) in which the MMI packet is transmitted.

[0053] Fig. 7 is a diagram showing an example of bit allocation for payload type, subframe number, layer number, and sub-layer number. MMI packetization section 106 sets the value of the data unit type based on, for example, the bit allocation shown in Fig. 7. In this way, MMI packetization section 106 includes, in the header (MMI header) added to the data unit for each layer, information indicating the subframe (subframe number) that transmits the data signal of that layer as control information corresponding to the TDM method.

[0054] Furthermore, the MMI packetization unit 106 includes, as control information compatible with the TDM method, information indicating the subframe (subframe number) in which the data signal of the corresponding layer is transmitted and the layer (layer number) in the subframe in the header (MMI header) added to the data unit for each layer. By doing so, even when one subframe is divided into multiple layers as shown in Figure 6C, it is possible to identify the subframe and layer in which the data signal is transmitted.

[0055] If synchronization control information is included in the payload of the MMI packet, all 8 bits of the data unit type are set to "0." That is, synchronization control MMI packet configuration section 107 sets all 8 bits of the data unit type included in the MMI header of the synchronization control MMI packet to "0."

[0056] 5 again, the sequence number indicates the order of each data unit type in the MMI packet. The sequence number starts from 0 and goes up to 65535, and then wraps around to 0 when it reaches 65535.

[0057] The data unit length indicates the data length of the payload. Stuff bits may be added to the synchronization control information and data units. The data unit length indicates the data length of the payload excluding the stuff bits.

[0058] FIG. 8 is a diagram showing the structure of the synchronization control information.

[0059] As shown in FIG. 8, the synchronization control information includes a transmission timestamp, a leap second identifier, a reservation, current frame synchronization control information, and stuffing.

[0060] The transmission timestamp indicates the time at which a packet was output from the packet transmission unit 109 of the remultiplexing unit 100. The leap second indicator indicates the system clock on which the transmission timestamp is set when leap second adjustment is performed on the system clock of the remultiplexing unit 100. The reserved bits are bits prepared for future expansion, and may be set to 0, for example. The current frame synchronization control information indicates the synchronization control information of the current OFDM frame. The stuffing bits are bits that do not contain information and are inserted to adjust the bit length of the synchronization control information. The size of the transmission timestamp is 8 bytes, and the size of the leap second identifier and reserved bits is 1 byte (leap second identifier: 2 bits, reserved: 6 bits). The size of the current frame synchronization control information varies depending on the frame configuration of the OFDM frame.

[0061] As shown in FIG. 8, the current frame synchronization control information includes frame synchronization information (4 bytes), TMCC (12 bytes), frame information (2 bytes), subframe information, layer information, sub-layer information, and network synchronization information.

[0062] The frame synchronization information is information for establishing frame synchronization. The TMCC indicates the TMCC information required for modulating the current OFDM frame.

[0063] The frame information indicates whether or not the TMCC information in the current OFDM frame has been updated, countdown information until the transmission parameters are switched if they are to be switched, the number of subframes included in the current OFDM frame, and so on.

[0064] The subframe information indicates the transmission parameters of the corresponding subframe. The subframe information corresponding to one subframe is 3 bytes, and indicates the number of subframes included in the current OFDM frame (N SF ) subframe information is provided. Therefore, the total subframe information is 3*N SF It is a byte.

[0065] The layer information indicates the transmission parameters of the corresponding layer. The layer information corresponding to one layer is 2 bytes, and the number of layers included in the current OFDM frame (N L ) hierarchical information is provided. Therefore, the total hierarchical information is 2*N SF It is a byte.

[0066] The sub-layer information indicates the transmission parameters of the corresponding sub-layer. The sub-layer information corresponding to one sub-layer is 5 bytes, and the number of sub-layers included in the current OFDM frame (N SL ) sub-hierarchical information is provided. Therefore, the total number of sub-hierarchical information is 5*N SL It is a byte.

[0067] The network synchronization information is information that specifies the timing at which a plurality of transmitting stations 3 that make up an SFN (Single Frequency Network) transmit broadcast waves. The network synchronization information includes, for example, information related to delay control such as maximum delay time and time offset. The size of the network synchronization information is determined by N SYNC It is a byte.

[0068] Next, the operation of generating an MMI packet by the multiplexing unit 100 according to this embodiment will be described with reference to FIG.

[0069] As mentioned above, for a coding rate of 7 / 16 and medium code length, the size of an FEC block is 8,640 bytes (FEC block header area: 2 bytes, main signal area: 3,754 bytes, BCH parity area: 24 bytes, LDPC parity area: 4,860 bytes). In XMI, FEC blocks are concatenated to form a multiplexed frame corresponding to one OFDM frame. In this case, one OFDM frame is 135,072 bytes, so only the first FEC block (FEC block 1) through partway through the 16th FEC block (FEC block 16) can be included in one multiplexed frame. The remainder of FEC block 16 must be transmitted in the next OFDM frame. Thus, when one FEC block spans multiple OFDM frames, a portion of the previously received FEC block must be buffered until the remaining portion is received, complicating the configuration and processing of the modulation device.

[0070] In this embodiment, the pseudo-FEC block constructor 104 constructs a pseudo-FEC block that does not include the LDPC parity portion of the FEC block. Therefore, in the example shown in FIG. 9, the size of the pseudo-FEC block is 3780 bytes. Therefore, as shown in FIG. 9, the pseudo-multiplex frame constructor 105 can construct a pseudo-multiplex frame that includes pseudo-FEC block 1 corresponding to FEC block 1 to pseudo-FEC block 16 corresponding to FEC block 16. Furthermore, the beginning of the next pseudo-multiplex frame will be the beginning of the 17th pseudo frame. Thus, in this embodiment, one pseudo-FEC block does not span across OFDM frames, which prevents the configuration and processing of the modulation device from becoming complicated.

[0071] As shown in Figure 9, in this embodiment, pseudo FEC blocks 1 to 16 (16 pseudo FEC blocks) are included in one pseudo multiplex frame (pseudo multiplex frame n), pseudo FEC blocks 17 to 32 (16 pseudo FEC blocks) are included in the next pseudo multiplex frame (pseudo multiplex frame n+1), pseudo FEC blocks 33 to 47 (15 pseudo FEC blocks) are included in the next pseudo multiplex frame (pseudo multiplex frame n+2), and pseudo FEC blocks 48 to 63 (16 pseudo FEC blocks) are included in the next pseudo multiplex frame (pseudo multiplex frame n+3). Specifically, pseudo-multiplex frame n contains 16 pseudo-FEC blocks because 135072 / 8649=15.6333; pseudo-multiplex frame n+1 contains 16 (=32-16) pseudo-FEC blocks because (135072×2) / 8649=31.2666666; and pseudo-multiplex frame n+2 contains 15 (=47-32) pseudo-FEC blocks because (135072×3) / 8649=46.9 (and so on). Because pseudo-multiplex frame n+2 contains one fewer pseudo-FEC block than the other pseudo-multiplex frames, one dummy pseudo-FEC block is inserted into pseudo-multiplex frame n+2. That is, a dummy pseudo-FEC block is inserted into the pseudo-multiplex frame every three pseudo-multiplex frames. This allows the frame length of each pseudo-multiplex frame to be constant.

[0072] The MMI packetization unit 106 divides the pseudo-multiplexed frame into data units of a predetermined size (1080 bytes in the example shown in Figure 9), and adds the headers (IPv4 header, UDP header, MMTP header, and MMI header) described with reference to Figure 4 to the data units to form MMI packets.

[0073] Packet sending unit 109 sends out a synchronization control MMI packet at the beginning of the OFDM frame, and then sends out MMI packets output from MMI packetization unit 106 of each layer at a constant rate. Packet sending unit 109 also sends out stuff MMI packets as necessary so that the number of MMI packets that make up the OFDM frame remains constant.

[0074] As described above, the multiplexing unit 100 serving as a multiplexing device according to the present disclosure includes a TLV packetizing unit 103, a pseudo-FEC block constructing unit 104, a pseudo-multiplex frame constructing unit 105, an MMI packetizing unit 106, and a packet transmitting unit 109. The TLV packetizing unit 103 encapsulates the data signal of each layer to generate a TLV packet. The pseudo-FEC block constructing unit 104 constructs a pseudo-FEC block for each layer, which is composed of a header area, a main signal area storing the TLV packets of that layer, and a BCH parity area. The pseudo-multiplex frame constructing unit 105 constructs a pseudo-multiplex frame corresponding to one OFDM frame by concatenating the pseudo-FEC blocks of that layer. The MMI packetizing unit 106 divides the pseudo-multiplex frame of that layer into fixed-length data units for each layer and generates an MMI packet by adding a header containing control information corresponding to the time division method to the data unit. The packet sending unit 109 multiplexes the MMI packets of each of the multiple layers and outputs them to the modulation device at a constant rate.

[0075] A pseudo multiplexed frame is divided into fixed-length data units, and a header (MMI header) containing control information corresponding to the time division method is added to the data units to form packets (MMI packets), thereby generating a program transmission signal corresponding to the TDM method.

[0076] In addition, a pseudo-multiplex frame is constructed from a pseudo-FEC block consisting of a header area, a main signal area storing TLV packets, and a BCH parity area (i.e., not including LDPC parity), and the pseudo-multiplex frame is divided into fixed-length data units to construct an MMI packet. Therefore, since there is no need to transmit LDPC parity, a decrease in transmission efficiency can be suppressed.

[0077] Furthermore, an MMI packet is a fixed-length data unit to which a header (fixed length) is added, and is therefore of a fixed length. Furthermore, the MMI packet is output at a constant rate. Since fixed-length MMI packets are output at a constant rate in this manner, the occurrence of jitter can be suppressed. Therefore, according to the present disclosure, it is possible to suppress a decrease in transmission efficiency and the occurrence of jitter, and to generate a program transmission signal compatible with the TDM system.

[0078] Although not specifically mentioned in the embodiments, a program may be provided that causes a computer to function as a remultiplexing device (remultiplexing unit 100). The program may also be recorded on a computer-readable medium. The computer-readable medium can be used to install the program on a computer. Here, the computer-readable medium on which the program is recorded may be a non-transitory recording medium. The non-transitory recording medium is not particularly limited, and may be, for example, a recording medium such as a CD-ROM or a DVD-ROM.

[0079] In addition, a chip may be provided that is configured with a memory that stores programs for executing each process performed by the remultiplexing device (remultiplexing unit 100) and a processor that executes the programs stored in the memory and is mounted on the remultiplexing device (remultiplexing unit 100).

[0080] Although the above-described embodiments have been described as typical examples, it will be apparent to those skilled in the art that many modifications and substitutions are possible within the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited by the above-described embodiments, and various modifications and changes are possible without departing from the scope of the claims. For example, multiple building blocks shown in the block diagrams of the embodiments can be combined into one, or one building block can be divided. [Explanation of symbols]

[0081] 1 Broadcasting System 2 Performance hall 3 Transmitting Station 4 transmitting antennas 21 Control terminal 22 Memory section 23 Advanced Transmission System 24 Current Transmission System 25 Transmitter 31 Receiving unit 32 Advanced Modulation Device 33 Advanced transmitter 34 Current system modulation device 35 Current system transmitter 100 Remultiplexer (Remultiplexer) 101 Packet Filter 102 IP header compression unit 103 TLV Packetization Unit 104 Pseudo FEC block component 105 Pseudo multiplex frame component 106 MMI Packetizer 107 Synchronous control MMI packet configuration section 108 Staff MMI Packet Component 109 Packet sending unit

Claims

1. A remultiplexing device that remultiplexes and outputs data signals of a plurality of layers to a modulation device that configures a time division OFDM frame in which data signals of a plurality of layers having different transmission capacities and delay tolerances are respectively assigned to a plurality of time-divided subframes, the remultiplexing device comprising: a TLV packetization unit for encapsulating a data signal of each layer to generate a TLV packet; a pseudo-FEC block constructing unit for constructing a pseudo-FEC block for each layer, the pseudo-FEC block being composed of a header area, a main signal area storing TLV packets of the layer, and a BCH parity area; a pseudo-multiplex frame constructing unit that constructs a pseudo-multiplex frame corresponding to one OFDM frame by concatenating the pseudo-FEC blocks of each layer; an MMI packetization unit that divides the pseudo-multiplex frame of each layer into fixed-length data units for each layer, and generates MMI packets by adding headers containing control information corresponding to the time division method to the data units; a packet sending unit that multiplexes the MMI packets of the plurality of layers and outputs the multiplexed MMI packets to the modulation device at a constant rate.

2. 2. The remultiplexing device according to claim 1, The MMI packetization unit includes, as the control information, information indicating a subframe in which a data signal of the layer is transmitted, in a header added to the data unit for each layer.

3. 3. The remultiplexing device according to claim 2, One subframe is frequency-divided into multiple layers, A remultiplexing device in which the MMI packetization unit includes, as the control information, information indicating a subframe in which a data signal of the layer is transmitted and a layer in the subframe in a header added to the data unit for each layer.

4. A program that causes a computer to function as the remultiplexing device according to claim 1.

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