JP2015065627A - Transmitter, receiver, digital broadcast system and chip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmitter, a receiver, a digital broadcast system and a chip, enabling a receiver to appropriately extract an error correction coding block, while suppressing the reduction of transmission efficiency.SOLUTION: A transmitter 10 includes: an error correction coding unit 11 for generating an error correction coding block having a fixed length; a framing unit 12 for generating a data frame constituted by the error correction coding block; and a MIMO-OFDM modulation unit 14 for transmitting a transmission frame including the data frame and a transmission control signal. The MIMO-OFDM modulation unit 14 transmits a pointer which indicates the offset of a top position of the error correction coding block, included at the top of the data frame, relative to the top position of the data frame, together with the data frame.

Description

  The present invention relates to a transmission device, a reception device, a digital broadcasting system, and a chip.

  In ISDB-T (Integrated Services Digital Broadcasting-Terrestrial), which is a terrestrial digital broadcasting system in Japan, a transmission apparatus is provided for each transmission frame (OFDM frame) composed of data frames and control signals (TMCC information and AC signals). Send video / audio data. The control signal is inserted into the transmission frame for each transmission frame. Further, the receiving device receives data such as video and audio by synchronizing transmission frames (for example, Non-Patent Document 1).

"Transmission standard for digital terrestrial television broadcasting" ARIB STD-B31

  By the way, in the next generation terrestrial broadcasting system, it is considered to insert an error correction code block (hereinafter referred to as FEC block) in which an error correction code is added to data into a data frame.

  In such a case, in order for the receiving apparatus to appropriately extract the FEC block, the start position of the FEC block included in the start of the transmission frame needs to match the start position of the transmission frame, and the FEC block is fixed. There is a constraint that it must be long.

  On the other hand, the capacity of the data frame is variable depending on the coding rate of the signal constituting the data frame and the modulation multi-level number, and it is difficult to adjust it to an integral multiple of the fixed-length FEC block. Therefore, when the FEC block cannot be inserted into the data frame, it is necessary to insert a null value in the remaining space in the data frame.

  As described above, there is a case where a Null value has to be inserted under the above-described constraint condition, so that transmission efficiency may be reduced.

  Therefore, the present invention has been made to solve the above-described problems, and a transmission device and a reception device that enable a reception device to appropriately extract an error correction code block while suppressing a decrease in transmission efficiency. An object is to provide a device, a digital broadcasting system, and a chip.

  The first feature includes a block generation unit that generates an error correction code block having a fixed length, a frame generation unit that generates a data frame constituted by the error correction code block, the data frame, and a transmission control signal. A transmission apparatus comprising: a transmission unit that transmits a transmission frame, wherein the transmission unit includes an offset of a head position of an error correction code block included in a head of the data frame with respect to a head position of the data frame together with the data frame The gist is to transmit a pointer indicating.

  A second feature is a receiving unit that receives a transmission frame including a data frame configured by an error correction code block having a fixed length and a transmission control signal, and an extraction unit that extracts the error correction code block from the data frame; The receiving unit receives a pointer indicating an offset of a head position of an error correction code block included in a head of the data frame with respect to a head position of the data frame together with the data frame, and The gist of the extraction unit is to extract an error correction code block included in the head of the data frame based on the pointer.

  A third feature is a chip mounted on a receiving device, which includes a receiving unit that receives a transmission frame including a data frame composed of error correction code blocks having a fixed length and a transmission control signal, and the data frame. An extraction unit for extracting the error correction code block, and the reception unit, together with the data frame, indicates an offset of the start position of the error correction code block included in the start of the data frame with respect to the start position of the data frame The gist is to receive a pointer, and the extraction unit extracts an error correction code block included at the head of the data frame based on the pointer.

  A fourth feature is a digital broadcasting system including a transmission device and a reception device, and the transmission device includes a block generation unit that generates an error correction code block having a fixed length and the error correction code block. A frame generation unit that generates a data frame; and a transmission unit that transmits a transmission frame including the data frame and a transmission control signal; and the reception device receives the transmission frame, and receives the transmission frame from the data frame. An extraction unit for extracting an error correction code block; and the reception unit includes a pointer indicating an offset of a head position of the error correction code block included in the head of the data frame with respect to the head position of the data frame together with the data frame The extraction unit receives the data frame based on the pointer. And summarized in that to extract the error-correction code blocks included in the beginning of.

  According to the present invention, it is possible to provide a transmission device, a reception device, a digital broadcasting system, and a chip that enable a reception device to appropriately extract an error correction code block while suppressing a decrease in transmission efficiency.

FIG. 1 is a block diagram illustrating a transmission device 10 according to the first embodiment. FIG. 2 is a block diagram illustrating the receiving device 20 according to the first embodiment. FIG. 3 is a diagram illustrating an example of a frame structure according to the first embodiment. FIG. 4 is a diagram illustrating an example of a frame structure according to the first embodiment.

  Next, an embodiment of the present invention will be described. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones.

  Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

[Outline of Embodiment]
First, a transmission device according to an embodiment includes a block generation unit that generates an error correction code block having a fixed length, a frame generation unit that generates a data frame including the error correction code block, and the data frame And a transmission unit for transmitting a transmission frame including a transmission control signal. The transmission unit transmits a pointer indicating an offset of the head position of the error correction code block included in the head of the data frame with respect to the head position of the data frame together with the data frame.

  Second, a receiving apparatus according to an embodiment includes a receiving unit that receives a transmission frame including a data frame and a transmission control signal configured by an error correction code block having a fixed length, and the error correction code block from the data frame. And an extraction unit for extracting. The receiving unit receives, together with the data frame, a pointer indicating an offset of a head position of an error correction code block included in the head of the data frame with respect to a head position of the data frame, and the extraction unit is based on the pointer Thus, an error correction code block included in the head of the data frame is extracted.

  In the embodiment, a pointer indicating an offset of the head position of the error correction code block included in the head of the data frame with respect to the head position of the data frame is transmitted from the transmitting device to the receiving device. Therefore, even if the head position of the error correction code block included at the head of the transmission frame does not coincide with the head position of the transmission frame, the receiving apparatus can extract the error correction code block. In other words, since the error correction code block is allowed to be arranged across a plurality of transmission frames (data frames), it is not necessary to insert a null value, and a decrease in transmission efficiency is suppressed.

[First Embodiment]
(Digital broadcasting system)
Hereinafter, the digital broadcast system according to the first embodiment will be described. FIG. 1 is a block diagram illustrating a transmission device 10 according to the first embodiment, and FIG. 2 is a block diagram illustrating a reception device 20 according to the first embodiment. The digital broadcasting system includes a transmission device 10 and a reception device 20.

  In the embodiment, the digital broadcasting system is a digital broadcasting system compatible with the next generation terrestrial broadcasting system. For example, in a digital broadcasting system, (Multiple Input Multiple Output) technology and OFDM (Orthogonal Frequency Division Multiplexing) technology are applied. In the digital broadcast system, hierarchical data (for example, 1 segment, 13 segments) belonging to a plurality of layers is transmitted from the transmission device 10 to the reception device 20. In the first embodiment, a case where A layer data, B layer data, and C layer data are transmitted as layered data will be exemplified.

  As illustrated in FIG. 1, the transmission apparatus 10 includes an error correction encoding unit 11, a framing unit 12, a control signal generation unit 13, and a MIMO-OFDM modulation unit 14. The transmission device 10 is provided in, for example, a broadcasting station.

  The error correction encoding unit 11 constitutes a block generation unit that generates an error correction code block having a fixed length. Specifically, the error correction encoding unit 11 assigns an error correction code to input data such as a TS (Transport Stream) having a predetermined format.

  In the first embodiment, A layer data, B layer data, and C layer data are transmitted as layered data. Therefore, the transmitting apparatus 10 includes an error correction encoding unit 11A that generates an error correction code block of A layer data, an error correction encoding unit 11B that generates an error correction code block of B layer data, and an error in C layer data. And an error correction encoding unit 11C that generates a correction code block.

  The framing unit 12 constitutes a frame generation unit that generates a data frame composed of error correction code blocks. In the first embodiment, the framing unit 12 inserts a pointer indicating the offset of the head position of the error correction code block included in the head of the data frame with respect to the head position of the data frame into the header of the data frame. The offset is a value indicating the number of bits from the head position of the data frame to the head position of the error correction code block included at the head of the data frame.

  Thus, since the pointer described above is inserted into the header of the data frame, the error correction code block may be arranged across a plurality of data frames (transmission frames). In other words, the head position of the error correction code block included at the head of the data frame (transmission frame) may not coincide with the head position of the data frame (transmission frame).

  In the first embodiment, A layer data, B layer data, and C layer data are transmitted as layered data. Accordingly, the transmission apparatus 10 includes a framing unit 12A that generates an error correction code block of A layer data, a framing unit 12B that generates an error correction code block of B layer data, and an error correction code block of C layer data. And a framing unit 12C for generation.

  The control signal generation unit 13 generates control signals such as a TMCC (Transmission and Multiplexing Configuration Control) signal and an AC (Auxiliary Channel) signal. For example, a TMCC signal (transmission control signal) is a signal indicating transmission parameters (modulation method, number of segments, coding rate, etc.) of a plurality of layers, and a synchronization signal for synchronizing an OFDM frame (transmission frame). Including.

  The MIMO-OFDM modulation unit 14 generates an OFDM frame (transmission frame) composed of the data frame output from the framing unit 12 and the control signal output from the control signal generation unit 13. An OFDM frame (transmission frame) is defined by a predetermined number of subcarriers (frequency axis) and a predetermined number of symbols (time axis).

  Subsequently, the MIMO-OFDM modulation unit 14 performs spatial coding processing on each symbol constituting the OFDM frame to generate two systems of signals, and performs carrier modulation and IFFT processing on the two systems of signals. Then, radio signals Tx1 and Tx2 are generated by performing orthogonal transformation. The MIMO-OFDM modulation unit 14 transmits the radio signals Tx1 and Tx to the reception device 20 using a plurality of antennas. The two signals may be the same signal, but are preferably different signals from the viewpoint of transmission efficiency.

  In the first embodiment, the above-described pointer is inserted into the header of the data frame. In other words, the MIMO-OFDM modulation unit 14 constitutes a transmission unit that transmits the above-described pointer together with the data frame.

  As illustrated in FIG. 2, the reception device 20 includes a frequency conversion unit 21, an orthogonal demodulation unit 22, a MIMO-OFDM demodulation unit 23, a carrier demodulation unit 24, a control signal demodulation unit 25, an extraction unit 26, And an error correction unit 27. The receiving device 20 is provided, for example, in a receiver fixedly installed in a home or a mobile terminal that can be carried by a user.

  The frequency converter 21 receives the radio signals Rx1 and Rx2 using a plurality of antennas. Specifically, the frequency converter 21 converts the radio signals Rx1 and Rx2 into baseband signals by frequency conversion and digitizes them by AD conversion or the like.

  In the first embodiment, since the radio signals Rx1 and Rx2 are received by a plurality of antennas, the receiving device 20 includes a frequency converter 21A that processes the radio signal Rx1 and a frequency converter 21B that processes the radio signal Rx2. .

  The orthogonal demodulation unit 22 performs orthogonal demodulation of the frequency component converted by the frequency conversion unit 21.

  In the first embodiment, since the radio signals Rx1 and Rx2 are received by a plurality of antennas, the receiving device 20 processes the signal corresponding to the radio signal Rx2 and the frequency converter 21A that processes the signal corresponding to the radio signal Rx1. Frequency conversion unit 21B.

  The MIMO-OFDM demodulation unit 23 performs an FFT process and a MIMO decoding process on the two systems of signals output from the frequency conversion unit 21A and the frequency conversion unit 21B to obtain a predetermined number of subcarriers (frequency axis) and a predetermined number. An OFDM frame (transmission frame) defined by the number of symbols (time axis) is acquired. The synchronization of the OFDM frame (transmission frame) is performed by the above-described TMCC signal.

  As described above, an OFDM frame (transmission frame) is composed of a data frame and a control signal, and the above-described pointer is included in the header of the data frame. Accordingly, in the first embodiment, the MIMO-OFDM demodulator 23 constitutes a receiver that receives the pointer described above together with the data frame.

  The carrier demodulation unit 24 performs carrier demodulation of symbols constituting a data frame in the OFDM frame (transmission frame).

  The control signal demodulator 25 performs carrier demodulation of symbols constituting the transmission control signal (TMCC signal) among the control signals included in the OFDM frame (transmission frame). In addition, the control signal demodulator 25 performs carrier demodulation of symbols constituting the AC signal among the control signals included in the OFDM frame (transmission frame).

  The extraction unit 26 extracts an error correction code block from the data frame. Specifically, the extraction unit 26 determines the error correction code block included in the head of the data frame based on a pointer indicating the offset of the head position of the error correction code block included in the head of the data frame with respect to the head position of the data frame. To extract. In addition, since the error correction code block has a fixed length, the extraction unit 26 can also extract other error correction code blocks if the start position of the error correction code block included in the head of the data frame can be specified. it can.

  In the first embodiment, A layer data, B layer data, and C layer data are transmitted as layered data. Therefore, the receiving apparatus 20 extracts an extraction unit 26A that extracts an error correction code block of A layer data, an extraction unit 26B that extracts an error correction code block of B layer data, and an error correction code block of C layer data. And an extraction unit 26C.

  The error correction unit 27 performs error correction on the bit string constituting the error correction code block output from the extraction unit 26.

  In the first embodiment, A layer data, B layer data, and C layer data are transmitted as layered data. Accordingly, the receiving apparatus 20 includes an error correction unit 27A that performs error correction of a bit string that forms an error correction code block of A layer data, and an error correction unit that performs error correction of a bit string that forms an error correction code block of B layer data. 27B and an error correction unit 27C that performs error correction of a bit string constituting an error correction code block of C layer data.

(Frame structure)
Hereinafter, an example of the frame structure according to the first embodiment will be described. FIG. 3 is a diagram illustrating an example of a frame structure according to the first embodiment.

  As shown in FIG. 3, the OFDM frame (transmission frame) is configured by symbols and control signals (TMCC signal and AC signal) constituting the data frame of each layer. As described above, an OFDM frame (transmission frame) is defined by a predetermined number of subcarriers (frequency axis) and a predetermined number of symbols (time axis).

  A data frame in each layer is composed of error correction code blocks (also referred to as FEC blocks). The error correction code block may be arranged across a plurality of data frames. The error correction code block has a fixed-length bit string, but the bit string length of the error correction code block may be different for each layer.

  The header of the data frame includes, for example, a synchronization bit (Sync), a pointer, a reserve bit, and an FEC parity bit. The synchronization bit (Sync) is a bit for specifying the head position of the data frame. As shown in FIG. 4, the pointer indicates an offset (number of bits) of the head position of the error correction code block included in the head of the data frame with respect to the head position of the data frame. The reserved bit is a bit string reserved for future expansion. The FEC parity bit is a bit for performing error correction of the header of the data frame.

(Function and effect)
In the first embodiment, a pointer indicating an offset of the head position of the error correction code block included in the head of the data frame with respect to the head position of the data frame is transmitted from the transmitting device 10 to the receiving device 20. Therefore, even if the head position of the error correction code block included in the head of the transmission frame does not coincide with the head position of the transmission frame, the receiving device 20 can extract the error correction code block. In other words, since the error correction code block is allowed to be arranged across a plurality of transmission frames (data frames), it is not necessary to insert a null value, and a decrease in transmission efficiency is suppressed.

[Other Embodiments]
Although the present invention has been described with reference to the above-described embodiments, it should not be understood that the descriptions and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  In the embodiment, the pointer indicating the offset of the head position of the error correction code block included in the head of the data frame with respect to the head position of the data frame is included in the header of the data frame. However, the embodiment is not limited to this. The header described above may be included in the transmission control signal (TMCC) instead of the header of the data frame.

  Although not particularly mentioned in the embodiment, the above-described pointer is an important bit string for extracting an error correction code block, and is preferably transmitted by BPSK. That is, it is preferable that lower-order carrier modulation is applied to the pointer described above than carrier modulation applied to the error correction code block.

  In the embodiment, the case where the hierarchical data is transmitted is illustrated, but the embodiment is not limited to this. Data transmitted from the transmission device 10 to the reception device 20 may not be hierarchized.

  In the embodiment, a system using a MIMO (Multiple Input Multiple Output) technology has been illustrated. However, the embodiment is not limited to this. The embodiment may be applied to a system in which a MISO (Multiple Input Single Output) technology or a SISO (Single Input Single Output) technology is used.

  Although not particularly mentioned in the embodiment, a program for causing a computer to execute each process performed by the transmission device 10 and the reception device 20 may be provided. The program may be recorded on a computer readable medium. If a computer-readable medium is used, a program can be installed in the 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, but may be a recording medium such as a CD-ROM or a DVD-ROM.

  Or the chip | tip comprised by the memory which memorize | stores the program for performing each process which the transmitter 10 and the receiver 20 perform, and the processor which executes the program memorize | stored in memory may be provided.

  DESCRIPTION OF SYMBOLS 10 ... Transmission apparatus, 11 ... Error correction encoding part, 12 ... Framing part, 13 ... Control signal production | generation part, 14 ... MIMO-OFDM modulation part, 20 ... Reception apparatus, 21 ... Frequency conversion part, 22 ... Orthogonal demodulation part , 23 ... MIMO-OFDM demodulator, 24 ... carrier demodulator, 25 ... control signal demodulator, 26 ... extractor, 27 ... error corrector

Claims (10)

A block generator for generating an error correction code block having a fixed length;
A frame generation unit for generating a data frame constituted by the error correction code block;
A transmission unit for transmitting a transmission frame including the data frame and a transmission control signal,
The transmission device transmits a pointer indicating an offset of a head position of an error correction code block included in a head of the data frame with respect to a head position of the data frame together with the data frame.   The transmission device according to claim 1, wherein the pointer is included in the transmission control signal.   The transmission device according to claim 1, wherein the pointer is included in a header of the data frame.   The transmission apparatus according to claim 1, wherein a modulation method of the pointer is BPSK. A receiving unit for receiving a transmission frame including a data frame and a transmission control signal configured by an error correction code block having a fixed length;
An extraction unit for extracting the error correction code block from the data frame,
The receiving unit receives a pointer indicating an offset of a head position of an error correction code block included in a head of the data frame with respect to a head position of the data frame together with the data frame;
The receiving apparatus, wherein the extracting unit extracts an error correction code block included in a head of the data frame based on the pointer.   The receiving device according to claim 5, wherein the pointer is included in the transmission control signal.   The receiving device according to claim 5, wherein the pointer is included in a header of the data frame.   The receiving apparatus according to claim 5, wherein a modulation method of the pointer is BPSK. A chip mounted on a receiving device,
A receiving unit for receiving a transmission frame including a data frame and a transmission control signal configured by an error correction code block having a fixed length;
An extraction unit for extracting the error correction code block from the data frame,
The receiving unit receives a pointer indicating an offset of a head position of an error correction code block included in a head of the data frame with respect to a head position of the data frame together with the data frame;
The chip, wherein the extraction unit extracts an error correction code block included at the head of the data frame based on the pointer. A digital broadcasting system comprising a transmitting device and a receiving device,
The transmission apparatus includes: a block generation unit that generates an error correction code block having a fixed length; a frame generation unit that generates a data frame including the error correction code block; and a transmission including the data frame and a transmission control signal A transmission unit for transmitting a frame,
The receiving device includes a receiving unit that receives the transmission frame, and an extracting unit that extracts the error correction code block from the data frame,
The receiving unit receives a pointer indicating an offset of a head position of an error correction code block included in a head of the data frame with respect to a head position of the data frame together with the data frame;
The extraction section extracts an error correction code block included in the head of the data frame based on the pointer.

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