JP2023124722A - Content transmission signal generation apparatus, ofdm frame generation apparatus, and program - Google Patents

Abstract

To improve transmission efficiency of content data.SOLUTION: A content transmission signal generation apparatus 100 includes: a TLV unit 106 which generates a TLV packet; an OFDM frame configuration information generation unit 107 which generates FEC block byte offset information, TLV storage byte offset information, and LLch offset information; a synchronization control packet configuration unit 103 which generates a synchronization control packet including the FEC block byte offset information; a byte offset addition unit 108 which adds the TLV storage byte offset information to a hierarchical data TLV packet to generate a hierarchical data packet; an LLch offset addition unit 109 which adds the LLch offset information to an LLch data TLV packet to generate an LLch data packet; and an insertion unit 111 which inserts sequence number to the synchronization control packet, the hierarchical data packet, and the LLch data packet, to generate a content transmission signal.SELECTED DRAWING: Figure 2

Description

The present invention relates to a content transmission signal generation device, an OFDM (Orthogonal Frequency Division Multiplexing) frame generation device, and a program.

In the advanced system for next-generation digital terrestrial television broadcasting (hereinafter referred to as "advanced system"), IP (Internet Protocol)-based XMI (Internet Protocol)-based XMI ( Using an eXtensible Modulator Interface) packet is under study (see, for example, Patent Document 1).

In addition, in recent years, due to large earthquakes, abnormal weather, etc., there is an increasing need to quickly convey information. Therefore, in order to deliver information with high immediacy such as earthquake early warnings to viewers with low delay, XMI is considering a low-delay transmission channel called LLch (Low Latency channel) that does not perform processing such as time interleaving. there is

In addition, in XMI, in order to realize SFN (Single Frequency Network), the program transmission signal is output from the re-multiplexer at a fixed length and at a constant rate in the same way as the current terrestrial digital broadcasting TS (Transport Stream). . For this reason, stuffing or null data is transmitted in portions where there is no actual data to achieve a fixed length and a constant rate, and parity portions of LDPC are filled with nulls before transmission. Regarding LLch transmission, a 5-byte LLch area is always reserved for one XMI packet other than synchronization control information. Therefore, even when there is no content to be transmitted on the LLch, empty data is always transmitted.

JP 2018-78551 A

In experiments on an advanced method using XMI packets, the transmission rate of XMI when transmitting video/audio data (content data) at about 30 Mbps with SISO (Single Input Single Output) was about 50 Mbps, and MIMO (Multiple Output) was used. Input Multiple Output) requires a transmission band of about 100 Mbps when transmitting content data of about 60 Mbps. That is, approximately 40% of the rate of XMI packets will be discarded at the station. In addition, the maximum transmission rate of STL (Studio to Transmitter Link)/TTL (Transmitter to Transmitter Link) for transmitting the content transmission signal of the current digital terrestrial broadcasting from the performance hall to the broadcasting station is about 40 Mbps with the current parameters. Therefore, it is impossible to transmit the content data of the advanced method in XMI packets using the existing STL transmitter.

SUMMARY OF THE INVENTION An object of the present invention, which has been made in view of such circumstances, is to provide a content transmission signal generation device, an OFDM frame generation device, and a program capable of improving the transmission efficiency of content data.

A content transmission signal generation device according to one embodiment is a content transmission signal generation device that transmits a content transmission signal to an OFDM frame generation device, and is a layer-specific TLV packet obtained by encapsulating a packet containing layer-specific content data into a TLV packet. A TLV conversion unit for generating a hierarchical data TLV packet and an LLch data TLV packet obtained by encapsulating a packet containing LLch data transmitted with a lower delay than the content data into a TLV packet, and the OFDM frame generation device. FEC block byte offset information indicating the byte offset from the OFDM frame beginning of the FEC block in the OFDM frame, TLV storage byte offset information indicating the storage location of the TLV packet in the FEC block, and the LLch data in the OFDM frame an OFDM frame configuration information generation unit that generates LLch offset information indicating an allocation position; a synchronization control packet configuration unit that generates a synchronization control packet including the FEC block byte offset information; and the TLV storage for the TLV packet. a byte offset addition unit that adds byte offset information to generate a hierarchical data packet; an LLch offset addition unit that adds the LLch offset information to the LLch data TLV packet to generate an LLch data packet; and the synchronization control. an insertion unit that inserts a sequence number into the packet, the layer data packet, and the LLch data packet to generate a content transmission signal.

Furthermore, in one embodiment, the LLch offset information may include information indicating a leading symbol position and a leading carrier position when allocating the LLch data to the OFDM frame.

Furthermore, in one embodiment, when the LLch data TLV packet is divided, the LLch offset information indicates whether the LLch data TLV packet after each division is the leading portion, the trailing portion, or the leading portion. and information indicating whether it is other than the final part.

Furthermore, in one embodiment, the inserting unit may further insert packet type information indicating which of the synchronization control packet, the hierarchical data packet, and the LLch data packet corresponds.

Further, an OFDM frame generation device according to one embodiment is an OFDM frame generation device that receives the content transmission signal from the content transmission signal generation device, prepares an FEC block area, and based on the TLV storage byte offset information a TLV mapping unit that maps the layer data TLV packets to the FEC block area; and a FEC block that concatenates the layer data TLV packets and stores the FEC blocks in the main signal area based on the FEC block byte offset information for one OFDM frame. a data processing unit that performs error correction encoding processing and interleaving processing on the FEC blocks; and an LLch that directly modulates the LLch data by a predetermined modulation method to generate LLch carrier symbols. and an OFDM frame constructing unit that constructs an OFDM frame by multiplexing the LLch carrier symbols to the data processed by the data processing unit.

A program according to one embodiment causes a computer to function as the content transmission signal generation device.

A program according to one embodiment causes a computer to function as the OFDM frame generation device.

According to the present invention, it is possible to improve the transmission efficiency of content data.

1 is a block diagram showing a configuration example of a distribution system according to one embodiment of the present invention; FIG. 1 is a block diagram showing a configuration example of a content transmission signal generation device according to an embodiment of the present invention; FIG. 4 is a diagram showing a configuration example of a TLV packet generated by the content transmission signal generation device according to one embodiment of the present invention; FIG. 4 is a flowchart showing an operation example of the content transmission signal generation device according to one embodiment of the present invention; FIG. 2 is a diagram showing the packet structure of a conventional XMI packet; 1 is a diagram showing a conventional FEC block and an OFDM frame; FIG. 4 is a diagram showing a configuration example of an STLP packet generated by the transmission signal generation device according to one embodiment of the present invention; FIG. FIG. 4 is a diagram showing a usage example of an LLch start flag and an LLch end flag generated by the transmission signal generation device according to one embodiment of the present invention; FIG. 4 is a diagram showing a usage example of LLch symbol offsets and LLch byte offsets generated by the transmission signal generator according to one embodiment of the present invention; 1 is a block diagram showing a configuration example of an OFDM frame generation device according to an embodiment of the present invention; FIG. FIG. 3 is a diagram showing a configuration example of an FEC block generated by the OFDM frame generation device according to one embodiment of the present invention; 5 is a flowchart showing an operation example of OFDM frame generation of the OFDM frame generation device according to one embodiment of the present invention;

An embodiment will be described in detail below with reference to the drawings.

(delivery system)
FIG. 1 is a diagram showing a configuration example of a distribution system 1 according to one embodiment of the present invention. A distribution system 1 shown in FIG. 1 includes a performance hall 10 and a broadcasting station 20 . The concert hall 10 includes a multiplexer 11 (11a-11c), a remultiplexer 12, and an STL transmitter 13. The broadcasting station 20 comprises an STL receiver 21 , a packet monitor 22 , a traffic smoother 23 , a modulator 24 and a transmitter 25 . The performance hall 10 and the broadcasting station 20 are connected via a content transmission line 30 as a network.

The multiplexing device 11a multiplexes content signals (video/audio signals and caption signals) for the A layer input from the outside, packetizes them into packets of a predetermined format, and sends them to the re-multiplexing device 12 as a package for the A layer. Output. In this embodiment, the multiplexing device 11 generates MMTP (MMT Protocol) packets, which are MMT (MPEG Media Transport) format packets.

Similarly, the multiplexer 11b multiplexes an externally input layer B content signal, packetizes it into packets of a predetermined format, and outputs the packet to the remultiplexer 12 as a layer B package. The multiplexing device 11c multiplexes content signals for layer C input from the outside, packetizes them into packets of a predetermined format, and outputs them to the re-multiplexing device 12 as packages for layer C. FIG.

A transmission line between the multiplexing device 11 and the re-multiplexing device 12 is an IP transmission line. Output.

The remultiplexing device 12 remultiplexes a plurality of hierarchical package data multiplexed by the multiplexing devices 11a, 11b, 11c and LLch data into one system, and transmits an SLTP format content transmission signal to the STL transmitter 13. Output.

The STL transmitter 13 transmits the content transmission signal to the broadcasting station 20 via the content transmission line 30 .

The STL receiver 21 receives the content transmission signal from the concert hall 10 via the content transmission line 30 .

The packet monitoring device 22 monitors packet transmission delays to stabilize broadcasting. For example, the packet monitor 22 monitors the time stamps of packets. This time stamp functions as a time stamp that indicates the transmission time that serves as a reference for the time at which the traffic smoother 23 should transmit the packet. Note that the broadcasting station 20 does not necessarily have to include the packet monitoring device 22 .

The traffic smoother 23 outputs packets at regular intervals with accurate time stamps. For example, the traffic smoother 23 corrects the time stamp of packets using time information obtained from an external GPS (Global Positioning System) server, PTP (Precision Time Protocol) server, NTP (Network Time Protocol) server, or the like. . Then, the traffic smoother 23 outputs the packet with the corrected time stamp to the modulation device 24 at the transmission time indicated by the corrected time stamp. Traffic smoother 23 need not be a dedicated device and may be in the form of computer software. Also, the packet monitoring device 22 may incorporate the traffic smoother 23 . Note that the broadcasting station 20 does not necessarily have to have the traffic smoother 23 .

The modulation device 24 modulates the timestamp-corrected packet input from the traffic smoother 23 and outputs the modulated packet to the transmitter 25 .

The transmitter 25 generates a broadcast wave according to the packet input from the modulator 24 and transmits it to the outside of the broadcasting station 20 via an antenna.

(content transmission signal generator)
Next, the content transmission signal generation device 100 according to one embodiment of the present invention will be described. The content transmission signal generation device 100 is incorporated into the re-multiplexer 12 or the functionality of the re-multiplexer 12 in associated equipment. The content transmission signal generation device 100 does not need to be dedicated hardware, and may be in the form of computer software.

A conventional content transmission signal generation device (remultiplexing device) generates TLV (Type Length Value) packets, constructs FEC blocks and OFDM frames from the TLV packets, and divides the OFDM frames into XMI packets. On the other hand, the content transmission signal generation device 100 according to the present invention generates a TLV packet and then generates a content transmission signal without generating an FEC block. The content transmission signal generation device 100 then transmits the content transmission signal to an OFDM frame generation device, which will be described later.

FIG. 2 is a block diagram showing a configuration example of the content transmission signal generation device 100. As shown in FIG. The content transmission signal generation device 100 shown in FIG. , a TLV (Type Length Value) conversion unit 106 , an OFDM frame configuration information generation unit 107 , a byte offset addition unit 108 , an LLch offset addition unit 109 , a hierarchical synthesis unit 110 and an insertion unit 111 .

The frame time generation unit 101 generates frame period information indicating the OFDM frame period and time information indicating time based on PTP (Precision Time Protocol)/NTP (Network Time Protocol) input from the outside. Then, frame time generating section 101 outputs frame period information to synchronization control packet forming section 103 and outputs time information to inserting section 111 . The time information is indicated, for example, in NTP (Network Time Protocol) format.

TMCC generating section 102 generates TMCC information based on externally input setting information (parameters of modulating device 24 , delay control information of relay stations, etc.), and outputs the generated TMCC information to synchronization control packet forming section 103 .

Based on the TMCC information generated by TMCC generation section 102 and the frame cycle information obtained from frame time generation section 101, synchronization control packet configuration section 103 generates an OFDM frame start instruction ( For example, 1 OFDM cycle flag information) is generated and output to OFDM frame configuration information generating section 107 .

Synchronization control packet configuration section 103 also generates a synchronization control packet containing OFDM frame synchronization control information and FEC block byte offset information obtained from OFDM frame configuration information generation section 107 , and outputs the synchronization control packet to insertion section 111 . . Details of the synchronization control packet will be described later.

The layer separation unit 104 receives an MMTP/IP packet of a content signal output from a transmission facility such as a master of the music hall 10, performs layer separation according to the packet type, and extracts a packet containing content data for each layer (this embodiment). layer data of layers A, B, and C), and LLch data transmitted with a lower delay than the content data (e.g., earthquake early warning). Output.

IP header compression section 105 compresses the IP header of the MMTP/IP packet separated by layer separation section 104 as necessary, and outputs the compressed IP header to TLV conversion section 106 .

The TLV conversion unit 106 encapsulates the packets containing content data for each layer A/B/C input from the IP header compression unit 105 into variable-length TLV packets to generate layer data TLV packets for each layer. Further, the TLV generating unit 106 generates an LLch data TLV packet by encapsulating a packet containing LLch data input from the IP header compression unit 105 into a variable-length TLV packet. TLV generating section 106 outputs the hierarchical data TLV packet to byte offset adding section 108 and outputs the LLch data TLV packet to LLch offset adding section 109 . Also, the TLV generating section 106 outputs packet length information of the layer data TLV packet and the LLch data TLV packet to the OFDM frame configuration information generating section 107 .

FIG. 3 is a diagram showing a configuration example of a TLV packet. In the following description, the number attached to each field indicates an example of the number of bits in each field.

As shown in FIG. 3, the TLV packet includes information on reserved area, packet type, data length, and data area. The packet type indicates the type of TLV packet. The packet type identifies whether the TLV packet is IPv4, IPv6, or compressed IP. The data length indicates the size of data stored in the data area. The TLV conversion unit 106 stores the IP packet input from the IP header compression unit 105 in the data area. As for the reserved area, for example, all bits may be set to "1".

OFDM frame configuration information generation section 107, based on the transmission mode, GI (Guard interval) ratio, TMCC information, etc. obtained from the setting information, and the OFDM frame start instruction input from synchronization control packet configuration section 103, the broadcasting station 20 from the OFDM frame head of the FEC block byte offset information (for example, 3-byte information) is generated and output to the synchronization control packet forming unit 103 . Note that the FEC block byte offset information may be information indicating the byte offset of the FEC block from the beginning of the OFDM frame when the OFDM frame is not straddled.

Further, the OFDM frame configuration information generating unit 107 is based on the code length and coding rate (encoding setting information) obtained from the setting information, and the packet length information of the TLV packet obtained from the TLV conversion unit 106 , obtaining information on the length of the LDPC parity part and the length of the FEC block, TLV storage byte offset information (for example, 3-byte information) indicating the storage location of the TLV packet of the A / B / C layer data in the FEC block, and broadcasting and LLch offset information (for example, 3-byte information) indicating the allocation position of LLch data in the OFDM frame configured at 20 . OFDM frame configuration information generating section 107 then outputs the TLV storage byte offset information to byte offset adding section 108 and outputs the LLch offset information to LLch offset adding section 109 . A specific example of the LLch offset information will be described later.

The byte offset addition unit 108 adds the TLV storage byte offset information input from the OFDM frame configuration information generation unit 107 to the layer data TLV packet input from the TLV generation unit 106 to generate a layer data packet, and layer synthesis. Output to unit 110 .

LLch offset adding section 109 generates an LLch data packet by adding the LLch offset information input from OFDM frame configuration information generating section 107 to the LLch data TLV packet input from TLV generating section 106 , and hierarchical combining section 110 . output to

Hierarchical synthesizing section 110 synthesizes (integrates) each hierarchical data packet for each hierarchical layer A/B/C input from byte offset adding section 108 and the LLch data packet input from LLch offset adding section 109 to generate a data packet. and output to the insertion unit 111 .

Inserting section 111 inserts a sequence number into the synchronization control packet input from synchronization control packet forming section 103 to generate an STLP (Studio to Transmitter Link Protocol) packet (hereinafter referred to as a "synchronization control STLP packet"). generated and output to the outside of the content transmission signal generation device 100 as a content transmission signal. The inserting unit 111 further inserts a time stamp (first time stamp) indicating the transmission time of the synchronization control STLP packet from the content transmission signal generation device 100 into the synchronization control packet input from the synchronization control packet forming unit 103. may Details of the STLP packet will be described later.

Inserting section 111 also inserts a sequence number into the hierarchical data packet input from hierarchical synthesizing section 110 to generate an STLP packet (hereinafter referred to as "hierarchical data STLP packet"), which is used as a content transmission signal. Output to the outside of the content transmission signal generation device 100 . Similarly, inserting section 111 inserts a sequence number into the LLch data packet input from hierarchical synthesizing section 110 to generate an STLP packet (hereinafter referred to as "LLch data STLP packet"), and generates a content transmission signal. , and output to the outside of the content transmission signal generation device 100 . Hereinafter, the hierarchical data STLP packet and the LLch data STLP packet are collectively referred to as "data STLP packet".

The inserting unit 111 may further insert packet type information indicating whether the packet is a synchronization control packet, a hierarchical data packet, or an LLch data packet. That is, the packet type information is information indicating the type of STLP packet, and a specific example will be described later.

Inserting section 111 transmits one synchronization control STLP packet at the beginning and then transmits a plurality of data STLP packets every OFDM time. Inserting section 111 may insert a time stamp (first time stamp) indicating the transmission time of the data STLP packet from content transmission signal generating apparatus 100 into the data packet input from hierarchical synthesizing section 110 . Alternatively, the inserting section 111 further adds the transmission time of the synchronization control STLP packet from the content transmission signal generation device 100 and the transmission time of the data STLP packet from the content transmission signal generation device 100 to the data packet input from the hierarchical synthesis section 110 . A time stamp (second time stamp) may be inserted that indicates the difference below the decimal point from the time.

Next, the operation of the content transmission signal generation device 100 will be described with reference to FIG. FIG. 4 is a flowchart showing an operation example of the content transmission signal generation device 100. As shown in FIG.

In step S101, PTP/NTP is input and frame cycle information and time information are generated.

In step S102, setting information is input and TMCC information is generated.

In step S103, an MMTP/IP packet of a content signal is input and layer separation is performed.

In step S104, the IP header is compressed for the MMTP/IP packet.

In step S105, a hierarchical data TLV packet and an LLch data TLV packet are generated.

In step S106, OFDM frame configuration information is acquired.

In step S107, FEC block byte offset information is generated based on the OFDM frame configuration information obtained in step S106.

In step S108, based on the OFDM frame configuration information obtained in step S106 and the packet length of the layer data TLV packet generated in step S105, TLV storage byte offset information indicating the storage location of the layer data TLV packet is generated.

In step S109, based on the OFDM frame configuration information obtained in step S106 and the packet length of the LLch data TLV packet generated in step S105, LLch offset information indicating the storage location of the LLch data TLV packet is generated.

At step S110, a synchronization control packet including the FEC block byte offset information generated at step S107 is generated.

In step S111, the TLV storage byte offset information generated in step S108 is added to the hierarchical data TLV packet to form a hierarchical data packet.

In step S112, the LLch offset information generated in step S109 is added to the LLch data TLV packet to configure the LLch data packet.

At step S113, a sequence number and a time stamp are inserted into the synchronization control packet generated at step S110 to generate and output a synchronization control STLP packet. Also, a sequence number and a time stamp are inserted into the hierarchical data packet generated in step S111 to generate and output a hierarchical data STLP packet. Also, a sequence number and a time stamp are inserted into the LLch data packet generated in step S112 to generate and output an LLch data STLP packet.

FIG. 5 shows the packet configuration of a conventional XMI packet for comparison with the present invention. A conventional XMI packet includes an IPv4 header, a UDP header, an MMTP packet header (MMTP header), and an XMI header as headers. Conventional XMI packets include an XMI packet in which synchronization control information is included in the data area shown in FIG. 5(a), an XMI packet in which only data is included in the data area shown in FIG. There are four types of XMI packets, the XMI packet shown in (c) containing data and stuff bits in the data area and the XMI packet shown in FIG. 5(d) in which the data area consists of stuff bits.

As shown in FIG. 5, in order to maintain the fixed length of the XMI packet, stuffing is performed by adding stuff bits to the synchronization control information and the data unit less than the packet length. If there is no data, a constant rate is maintained by sending stuff bits as shown in FIG. 5(d). However, in this configuration, since the parity area of the FEC block is filled with nulls, useless packets are sent to the line, and there is a risk of an increase in the transmission rate and packet loss on the line.

FIG. 6 is a diagram showing conventional FEC blocks and OFDM frames. Here, an example of a coding rate of 7/16 and a code length of Middle is shown. In this case, the LDPC parity occupies 9/16 (4860 bytes) of the FEC block of 8640 bytes, resulting in a wasteful signal.

<STLP packet>
Next, an STLP packet according to one embodiment of the present invention will be described. FIG. 7 is a diagram showing a configuration example of an STLP packet (packet of content transmission signal) according to one embodiment of the present invention. FIG. 7(a) shows a synchronization control STLP packet, FIG. 7(b) shows an example of a layer data STLP packet, and FIG. 7(c) shows a layer data STLP packet with null layer data (hereinafter referred to as , referred to as a “null STLP packet”), and FIG. 7(d) shows an LLch data STLP packet. Note that the structure of the STLP packet is not limited to this example.

An STLP packet includes an IPv4 header, a UDP header, packet type information, a sequence number, and a time stamp. The packet type information, sequence number, and time stamp are inserted by the inserting unit 111 . The packet type information and sequence number are included in the XMI header of the conventional XMI packet. A frame number indicating the frame number of the OFDM frame and a frame number flag indicating the presence or absence of the frame number may be inserted into the STLP packet by the inserting section 111 .

The synchronization control STLP packet shown in FIG. 7(a) contains synchronization control information. The synchronization control information includes FEC block byte offset information indicating the byte offset of the FEC block from the beginning of the OFDM frame, generated by OFDM frame configuration information generating section 107 . This enables the FEC block to be configured on the side of the broadcasting station 20 that has received the content transmission signal. Also, the synchronization control information includes TMCC information, time information indicating the time at which the next OFDM frame should be transmitted, and the like.

The hierarchical data STLP packet shown in FIG. 7B and the null STLP packet shown in FIG. and a generated hierarchical data TLV packet or a Null TLV packet. Hierarchical data TLV packets and null TLV packets can be streamlined by transmitting input IP packets in TLV format without stuffing them to a fixed length. By placing the TLV storage byte offset information before the TLV packet and obtaining the byte offset information from the beginning of the OFDM frame, it is possible to know the beginning of the OFDM frame.

The LLch data STLP packet shown in (d) of FIG. There are two types of LLch data STLP packets, an L0ch data STLP packet corresponding to partial reception and an L1ch data STLP packet corresponding to fixed reception, and these are collectively referred to as LLch data STLP packets. By transmitting the input IP packet in the TLV format without stuffing the LLch data TLV packet to a fixed length, it is possible to slim down the packet.

The synchronization control STLP packet, layer data STLP packet, null STLP packet, and LLch data STLP packet may be distinguished by 3-bit packet type information. For example, as shown in Table 1, the STLP packet type can be determined by prescribing the STLP packet corresponding to the value of the packet type information.

The LLch offset information shown in FIG. 7(d) includes a 1-bit LLch start flag, a 1-bit LLch end flag, a 5-bit reserved area, a 9-bit LLch symbol offset, and an 8-bit LLch byte offset.

<<LLch start flag and LLch end flag>>
Next, the LLch start flag and LLch end flag included in the LLch offset information will be described. When the LLch data TLV packet is divided, the LLch start flag and the LLch end flag indicate whether the LLch data TLV packet after each division is the beginning part, the end part, or other than the beginning part and the end part. contains information indicating whether Table 2 shows specific examples of the LLch start flag and the LLch end flag.

FIG. 8 is a diagram showing a usage example of the LLch start flag and the LLch end flag described in Table 2. FIG. As shown in FIG. 8, when the data of the LLch data TLV packet is long and the LLch data STLP packet exceeds the MTU (Maximum Transmission Unit) size of 1500 bytes, the LLch data TLV packet is divided and the MTU Do not exceed size. In this figure, the LLch data TLV packet is divided into three, and the divided LLch data TLV packets are called LLch data TLV packets (1) to (3).

The LLch start flag is set to 1 when the first LLch data TLV packet (1) is included. The LLch start flag is set to 0 in the LLch data STLP packet containing the LLch data TLV packet (2) and the LLch data TLV packet (3). On the other hand, the LLch end flag is set to 1 only for the LLch data STLP packet carrying the LLch data TLV packet (3), which contains the data at the end of the LLch data TLV packet. By setting in this way, in this emergency information, LLch data TLV (1) is the first information, and LLch data TLV packet (2) and LLch data TLV packet (3) are the previous LLch data TLV packets. Remaining data can be immediately recognized. At the same time, it can be seen that the LLch Data TLV packet (3) is the last part of the LLch Data TLV packet.

<<LLch symbol offset and LLch byte offset>>
Next, LLch symbol offsets and LLch byte offsets included in LLch offset information will be described.

FIG. 9 is a diagram showing a usage example of LLch symbol offsets and LLch byte offsets. FIG. 9(a) is a schematic diagram showing the spectrum of an OFDM signal in the advanced scheme. The OFDM signal in the advanced scheme has a frequency bandwidth of 5.83 MHz (approximately 6 MHz) and may have 35 segments. In the case of 16k-FFT (Fast Fourier Transform) mode, 8 LLch data carriers (LLch carriers) exist per segment, and 280 LLch carriers exist in the total 35 segments. In addition, in FIG. 9A, the LLch carrier is indicated by a thick line.

FIG. 9(b) is a diagram showing assignment of LLch data to carrier symbols, where only 280 LLch carriers in one OFDM frame are extracted and shown. In order to configure the same OFDM frame with a plurality of modulation devices, the LLch offset information uniquely determines to which carrier symbol the LLch data is assigned. In the example shown in FIG. 9B, the LLch symbol offset indicates the leading symbol position to which LLch data is assigned, and the LLch byte offset indicates the leading carrier position to which LLch data is assigned. That is, the LLch symbol offset and the LLch byte offset make it possible to specify the starting position of the carrier symbol when allocating the LLch data to the OFDM frame.

The bitstream of LLch data TLV packets is assigned to the LLch carrier symbols of the OFDM frame after being modulated. When the bit stream of the LLch data TLV packet is DBPSK (Differential Binary Phase-Shift Keying) modulated, each LLch carrier symbol becomes 1-bit data as shown in FIG. 9(b).

The content transmission signal generation device 100 can thus improve transmission efficiency of content data by generating STLP packets that are slimmer than XMI packets.

Multiple broadcast stations 20 can construct FEC blocks and OFDM frames by receiving synchronization control STLP packets and data STLP packets. In addition, when a plurality of broadcasting stations 20 convert STLP packets into XMI packets, the same XMI packet containing emergency information can be constructed. Therefore, since the same OFDM frame can be constructed, it is possible to construct an SFN.

Also, since the STLP packet has a sequence number in its header, it is possible to apply conventional error correction technology such as Pro-MPEG (Moving Picture Experts Group).

In addition, clock generation/synchronization with reference to absolute time becomes possible by adding a time stamp to the synchronization control STLP packet and transmitting all the data packets with the differential time after the decimal point.

Also, by putting the LLch start flag and the LLch end flag on the LLch data STLP packet, debugging and STLP analysis can be easily performed.

Furthermore, since the LLch does not constitute an FEC block and is directly assigned to symbols, it is possible to transmit video and audio in a shorter time than A/B/C layer video/audio. Effective for high information.

(OFDM frame generator)
Next, the OFDM frame generation device 200 according to one embodiment of the present invention will be described. OFDM frame generator 200 is incorporated in STL receiver 21 , packet monitor 22 , traffic smoother 23 or modulator 24 . The OFDM frame generator 200 need not be dedicated hardware and may be in the form of computer software.

The OFDM frame generation device 200 receives the content transmission signal from the content transmission signal generation device 100 and generates an OFDM frame.

FIG. 10 is a block diagram showing a configuration example of the OFDM frame generation device 200. As shown in FIG. OFDM frame generation apparatus 200 shown in FIG. 10 includes packet filter section 201, layer separation section 202, TLV mapping section 203, FEC block formation section 204, energy spreading section 205, error correction coding section 206, A bit interleaving unit 207, a mapping unit 208, a hierarchical synthesis unit 209, a frame header addition unit 210, a time/frequency interleaving unit 211, a TMCC analysis unit 212, an LLch modulation unit 213, and a pilot signal generation unit 214 , an OFDM frame configuration unit 215 and an OFDM transmission processing unit 216 .

Packet filter section 201 removes the IPv4 header and UDP header from the content transmission signal (STLP packet) received from content transmission signal generation apparatus 100 , and outputs the signal to layer separation section 202 .

The layer separation unit 202 separates the layer data STLP packet into each layer and distributes it to the processing system of each layer. It also outputs LLch data STLP packets to LLch modulation section 213 . Layer separation section 202 also outputs synchronization control information included in the synchronization control STLP packet to TMCC analysis section 212 .

The TLV mapping unit 203 prepares an FEC block area, maps the layer data TLV packet to the FEC block area based on the TLV storage byte offset information included in the layer data STLP packet, and outputs it to the FEC block formation unit 204 .

Based on the FEC block byte offset information contained in the synchronization control STLP packet, the FEC block forming unit 204 forms FEC blocks for one OFDM frame, which are stored in the main signal area by concatenating the layer data TLV packets, and the energy spreading unit 205 output to

FIG. 11 is a diagram illustrating a configuration example of an FEC block. As shown in FIG. 11, the FEC block includes an FEC block header, a main signal area, a BCH parity area, an LDPC parity area, and may also include a stuff bit area.

The FEC block header is information indicating the head position of the first TLV packet stored in the main signal area of the FEC block by the number of bytes from the head of the FEC block excluding the FEC block header.

As for the size of the FEC block, three sizes are set according to the code length (Short, Middle, Long) of LDPC (Low Density Parity Check) encoding performed by the transmitter 25 . Also, the sizes of the main signal area, stuff bit area, and LDPC parity area are determined according to the coding rate. The BCH parity area is fixed at 24 bytes.

Energy spreading section 205 performs energy spreading processing on the FEC block input from FEC block forming section 204 and outputs the result to error correction encoding section 206 .

Error correction coding section 206 performs error correction coding (LDPC coding in this embodiment) on the signal input from energy spreading section 205 so as to enable transmission errors to be corrected on the receiving side, and generates a coded signal. do. Error correction coding section 206 then outputs the generated coded signal to bit interleaving section 207 .

Bit interleaving section 207 interleaves the coded signal input from error correction coding section 206 bit by bit to generate bit data in order to improve the performance of the error correction code. Bit interleaving section 207 then outputs the generated bit data to mapping section 208 .

Mapping section 208 maps the bit data input from bit interleaving section 207 onto the IQ plane, and generates carrier symbols subjected to carrier modulation according to the modulation scheme. Mapping section 208 then outputs the generated carrier symbols to hierarchical combining section 209 .

Hierarchical synthesizing section 209 synthesizes the carrier symbols input from mapping section 208 of each hierarchy, and outputs the result to frame header adding section 210 .

Frame header adding section 210 adds a frame header to the carrier symbol input from hierarchical synthesis section 209 and outputs the carrier symbol to time/frequency interleaving section 211 .

The time/frequency interleaving section 211 rearranges the order of the carrier symbols input from the frame header adding section 210 in the time direction and the frequency direction to generate an interleaved signal. Time/frequency interleaving section 211 then outputs the generated interleaved signal to OFDM frame forming section 215 .

TMCC analysis section 212 generates a TMCC signal from the synchronization control information input from layer separation section 202 and outputs the TMCC signal to OFDM frame construction section 215 .

LLch modulation section 213 directly converts the LLch data included in the LLch data STLP packet input from layer separation section 202 (that is, without performing energy spreading processing, error correction coding processing, interleaving processing, etc.) to a predetermined modulation scheme ( For example, it modulates with DBPSK) to generate LLch carrier symbols and outputs them to OFDM frame construction section 215 .

Pilot signal generation section 214 generates pilot signals (SP signal and CP signal) and outputs them to OFDM frame construction section 215 .

OFDM frame configuration section 215 inserts the TMCC signal input from TMCC analysis section 212 and the pilot signal input from pilot signal generation section 214 into the interleaved signal input from time/frequency interleaving section 211, and inserts the LLch modulation section 213 LLch carrier symbols input from are multiplexed to form an OFDM frame. OFDM frame construction section 215 then outputs the generated OFDM frame to OFDM transmission processing section 216 .

OFDM frame construction section 215 inserts LLch carrier symbols based on the positions indicated by the above-described LLch symbol offset and LLch byte offset.

OFDM transmission processing section 216 performs OFDM modulation processing on the OFDM frame input from OFDM frame construction section 215 to generate an OFDM signal, and transmits the generated OFDM signal to the receiving apparatus. More specifically, OFDM transmission processing section 216 performs IFFT (Inverse Fast Fourier Transform) processing on the OFDM symbols of the OFDM frame input from OFDM frame construction section 215 to generate effective symbols in the time domain. Generate a signal. Then, OFDM transmission processing section 216 inserts a guard interval at the beginning of the effective symbol signal, and then performs orthogonal modulation processing and D/A conversion processing to generate an OFDM signal.

Next, the OFDM frame generation operation of the OFDM frame generation device 200 will be described with reference to FIG. FIG. 12 is a flow chart showing an operation example of OFDM frame generation of the OFDM frame generation device 200 .

In step S201, layer-separated layer data STLP packets are acquired, and generation of the n-th OFDM frame is started based on TMCC information.

In step S202, generation of FEC blocks is started. That is, an FEC block area is prepared.

In step S203, the layer data TLV packet is mapped based on the TLV storage byte offset information included in the layer data STLP packet.

In step S204, it is determined whether or not the configuration of the FEC block area is completed. If the configuration of the FEC block area has not been completed, the process returns to step S203, and if the configuration of the FEC block area has been completed, the process proceeds to step S205.

In step S205, it is determined whether or not the configuration of the OFDM frame is completed. That is, it is determined whether or not the FEC block area for one OFDM frame capacity is filled with layer data TLV packets. If the configuration of the OFDM frame has not been completed, the process returns to step S202. When the configuration of the FEC block area is completed, 1 is added to n in step S206, and the process returns to step S201 to configure a new OFDM frame.

In step S301, layer-separated LLch data STLP packets are obtained, and the bitstream of the LLch data TLV packets is DBPSK-modulated.

In step S302, LLch carrier symbols are multiplexed in the nk-th OFDM frame. Here, k is an integer greater than or equal to 1, and the value of k varies according to time interleaving parameters.

The OFDM frame generation device 200 performs time interleaving processing on hierarchical data. In the time interleaving processing, one or more OFDM frames are stored in a buffer and interleaving processing is performed in the time direction. It will take a long time. The time length of one OFDM frame is approximately 300 msec. On the other hand, since OFDM frame generation apparatus 200 does not time-interleave processing for LLch data, it is possible to allocate LLch data STLP packets to OFDM frames prior to OFDM frame allocation of hierarchical data STLP packets, and to minimize emergency information. It can be delivered on time.

In addition, it becomes possible to construct OFDM frames having the same waveform that can construct an SFN in the broadcasting station 20 (OFDM frame generation device 200).

As described above, in the present invention, content transmission is performed with a slimmed-down packet configuration, and FEC block generation and OFDM frame generation are performed on the broadcasting station 20 (OFDM frame generation device 200) side. It becomes possible to transmit at a rate close to the data capacity of the original voice data. Therefore, it is possible to transmit advanced content data using the same transmission parameters as existing STL transmitters and STL receivers.

(program)
It is also possible to use a computer capable of executing program instructions to function as the content transmission signal generation device 100 or the OFDM frame generation device 200 described above. The computer stores a program describing the processing details for realizing each function of the content transmission signal generation device 100 or the OFDM frame generation device 200 in the memory of the computer, and the processor of the computer reads and executes the program. do. A part of these processing contents may be realized by hardware. Here, the computer may be a general-purpose computer, a dedicated computer, a workstation, a PC (Personal Computer), an electronic notepad, or the like. Program instructions may be program code, code segments, etc. for performing the required tasks. The processor may be a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), a DSP (Digital Signal Processor), or the like.

Also, this program may be recorded in a computer-readable recording medium. By using such a recording medium, it is possible to install the program in the computer. Here, the recording medium on which the program is recorded may be a non-transitory recording medium. The non-transitory recording medium is not particularly limited, but may be, for example, a recording medium such as a CD-ROM or a DVD-ROM. This program can also be provided by download over a network.

Although the above embodiments have been described as representative examples, it will be apparent to those skilled in the art that many modifications and substitutions may be made within the spirit and scope of the invention. Therefore, the present invention should not be construed as limited by the embodiments described above, and various modifications and changes are possible without departing from the scope of the claims. For example, it is possible to integrate a plurality of configuration blocks described in the configuration diagrams of the embodiments, or to divide one configuration block. In addition, the plurality of steps described in the flowcharts of the embodiments are executed in parallel or in a different order according to the processing capability of the device that executes each step, or as necessary, instead of being executed in chronological order according to the description. may be executed.

1 distribution system 10 concert hall 11 multiplexer 12 remultiplexer 13 STL transmitter 20 broadcasting station 21 STL receiver 22 packet monitor 23 traffic smoother 24 modulator 25 transmitter 30 content transmission line 100 content transmission signal generator 101 Frame time generation unit 102 TMCC generation unit 103 Synchronization control packet configuration unit 104 Layer separation unit 105 IP header compression unit 106 TLV conversion unit 107 OFDM frame configuration information generation unit 108 Byte offset addition unit 109 LLch offset addition unit 110 Hierarchy synthesis unit 111 Insertion Section 200 OFDM Frame Generation Apparatus 201 Packet Filter Section 202 Layer Separation Section 203 TLV Mapping Section 204 FEC Block Formation Section 205 Energy Spreading Section 206 Error Correction Encoding Section 207 Bit Interleaving Section 208 Mapping Section 209 Layer Synthesis Section 210 Frame Header Addition Section 211 Time/Frequency Interleaving Section 212 TMCC Analysis Section 213 LLch Modulation Section 214 Pilot Signal Generation Section 215 OFDM Frame Configuration Section 216 OFDM Transmission Processing Section

Claims (7)

A content transmission signal generation device for transmitting a content transmission signal to an OFDM frame generation device,
Hierarchical data TLV packets in which packets containing content data in each hierarchy are encapsulated in TLV packets, and LLch data TLV in which packets containing LLch data transmitted with a lower delay than the content data are encapsulated in TLV packets. a TLVization unit that generates a packet;
FEC block byte offset information indicating the byte offset from the beginning of the OFDM frame of the FEC block in the OFDM frame configured by the OFDM frame generation device, TLV storage byte offset information indicating the storage location of the TLV packet in the FEC block, an OFDM frame configuration information generator that generates LLch offset information indicating the allocation position of the LLch data in an OFDM frame;
a synchronization control packet configuration unit that generates a synchronization control packet including the FEC block byte offset information;
a byte offset addition unit that adds the TLV storage byte offset information to the TLV packet to generate a hierarchical data packet;
an LLch offset addition unit that adds the LLch offset information to the LLch data TLV packet to generate an LLch data packet;
an insertion unit that inserts a sequence number into the synchronization control packet, the hierarchical data packet, and the LLch data packet to generate a content transmission signal;
A content transmission signal generation device comprising: 2. The content transmission signal generation apparatus according to claim 1, wherein said LLch offset information includes information indicating a leading symbol position and a leading carrier position when allocating said LLch data to said OFDM frame. When the LLch data TLV packet is divided, the LLch offset information indicates whether the LLch data TLV packet after each division is the beginning part, the end part, or other than the beginning part and the end part. 3. The content transmission signal generation device according to claim 1 or 2, comprising information indicating the. The content according to any one of claims 1 to 3, wherein the inserting unit further inserts packet type information indicating which of the synchronization control packet, the hierarchical data packet, and the LLch data packet corresponds. Transmission signal generator. An OFDM frame generation device for receiving the content transmission signal from the content transmission signal generation device according to any one of claims 1 to 4,
a TLV mapping unit that prepares an FEC block area and maps the layer data TLV packet to the FEC block area based on the TLV storage byte offset information;
an FEC block forming unit for forming one OFDM frame of FEC blocks in which the hierarchical data TLV packets are concatenated and stored in a main signal area based on the FEC block byte offset information;
a data processing unit that performs error correction coding processing and interleaving processing on the FEC blocks;
an LLch modulation unit that directly modulates the LLch data with a predetermined modulation scheme to generate an LLch carrier symbol;
an OFDM frame constructing unit configured to construct an OFDM frame by multiplexing the LLch carrier symbols to the data processed by the data processing unit;
An OFDM frame generator, comprising: A program for causing a computer to function as the content transmission signal generation device according to any one of claims 1 to 4. A program for causing a computer to function as the OFDM frame generation device according to claim 5.

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