JP6296739B2 - Transmitter - Google Patents

Description

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

  In the ISDB-T (Integrated Services Digital Broadcasting-Terrestrial) system, which is a terrestrial digital broadcasting system in Japan, an OFDM frame composed of 204 OFDM (Orthogonal Frequency Division Multiplexing) symbols is used as a transmission data format.

  The OFDM frame length in the ISDB-T system (the time length of the OFDM frame), as shown in (Equation 1), in addition to the number of OFDM symbols per OFDM frame, the bandwidth per segment (segment bandwidth) ) It is uniquely determined by Bws, the number of carriers C per segment, and the guard interval (GI) length.

  OFDM frame length = number of OFDM symbols per OFDM frame × (C / Bws + GI length) (Equation 1)

  Actually, as shown in FIG. 5, in the OFDM frame configuration in the ISDB-T system, the segment bandwidth Bws is fixed at 428.571 kHz, and the number of OFDM symbols per OFDM frame is fixed at 204. is there.

  In ISDB-T mode 3, the number of carriers per segment is set to 432, the guard interval length is set to 1/8, and the OFDM frame length is set to 231.336 ms.

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

  In the next-generation terrestrial broadcasting system, in order to realize further large-capacity transmission, to increase the number of carriers per segment by increasing the FFT (Fast Fourier Transform) size, and to use the band more efficiently In addition, reduction of the segment bandwidth Bws is being studied.

  Parameters such as FFT size and segment bandwidth Bws can be arbitrarily set for each broadcasting station.

  However, when (Formula 1) that defines the OFDM frame configuration in the ISDB-T system is applied to the next-generation terrestrial broadcasting system, the number of carriers C per segment increases as the FFT size increases, and the OFDM frame length becomes ISDB- It becomes longer than the OFDM frame length in the T method.

  As a result, there is a problem that it takes time to establish synchronization and switch viewing channels, and the convenience of viewers deteriorates.

  Further, when the OFDM frame length is different for each broadcasting station, there is a problem that the viewing channel switching time is different for each broadcasting station.

  In particular, in the operation of switching the viewing channel instantaneously (channel zapping operation) such as broadcasting station A → broadcasting station B → broadcasting station C → broadcasting station D... According to the difference in OFDM frame length for each broadcasting station, Each channel switching time results in a different result, and there is a problem that convenience for viewers is deteriorated.

  Therefore, the present invention has been made in view of the above-described problems, and a transmission device, a reception device, a chip, and a digital broadcasting system that can avoid a situation where the convenience of the viewer is deteriorated in the next-generation terrestrial broadcasting system. The purpose is to provide.

  A first feature of the present invention is a transmission apparatus, an OFDM frame configuration unit configured to generate an OFDM frame corresponding to an input signal based on an input segment bandwidth and FFT size And a transmission unit configured to transmit a transmission signal generated by performing a predetermined process on the generated OFDM frame, and the OFDM frame generated by the OFDM frame configuration unit The gist is that the length of the frame is configured to be a fixed length defined for each added gart interval length.

  A second feature of the present invention is a receiving device, which is configured to detect a segment bandwidth and an FFT size from a transmission signal transmitted by the transmitting device, and based on the FFT size. The input signal based on the number of OFDM symbols per OFDM frame corresponding to the combination of the segment bandwidth and the FFT size, and an FFT unit configured to perform FFT processing on the input signal And a signal demodulator configured to perform a demodulation process.

  A third feature of the present invention is a chip mounted on a receiving device, which is configured to detect a segment bandwidth and an FFT size from a transmission signal transmitted by the transmitting device; Based on the FFT unit configured to perform FFT processing on the input signal based on the FFT size, and on the number of OFDM symbols per OFDM frame corresponding to the combination of the segment bandwidth and the FFT size And a signal demodulator configured to perform demodulation processing on the input signal.

  A fourth feature of the present invention is a digital broadcasting system including a plurality of transmission apparatuses, and the length of the OFDM frame generated by each of the plurality of transmission apparatuses is the same as the added gart interval length. In some cases, they are configured to be the same, and the gist is that the segment bandwidth and the FFT size are variable in each configuration of the OFDM frame.

  As described above, according to the present invention, it is possible to provide a transmission device, a reception device, a chip, and a digital broadcasting system that can avoid a situation where the viewer's convenience deteriorates in the next-generation terrestrial broadcasting system. .

It is a functional block diagram of the transmission apparatus which concerns on the 1st Embodiment of this invention. It is a functional block diagram of the receiver which concerns on the 1st Embodiment of this invention. It is a figure which shows an example of the OFDM frame structure (per segment) used with the digital broadcasting system which concerns on the 1st Embodiment of this invention. It is a figure which shows an example of the OFDM frame structure (per 1 channel) used with the digital broadcasting system which concerns on the 1st Embodiment of this invention. It is a figure which shows an example of the OFDM frame structure (per segment) used with the conventional ISDB-T system.

(Digital broadcasting system according to the first embodiment of the present invention)
A digital broadcast system according to the first embodiment of the present invention will be described with reference to FIGS.

  The digital broadcast system according to the present embodiment is a digital broadcast system compatible with the next-generation terrestrial broadcast system, and includes the transmission device 10 shown in FIG. 1 and the reception device 30 shown in FIG. For example, it is assumed that the transmission device 10 is installed in a broadcasting station and the reception device 30 is installed in each home.

  Here, in the digital broadcast system according to the present embodiment, the transmission device 10 is configured to be able to transmit signals belonging to a plurality of layers.

  Such a hierarchy includes a hierarchy (for example, 1 segment) where a partial reception signal is transmitted, a hierarchy (for example, 12 segments) where a non-partial reception signal is transmitted, and the like. For example, a mobile reception service (one-segment broadcasting service) signal is assumed as the partial reception signal, and a fixed reception service signal is assumed as the non-partial reception signal.

  Note that the transmission device 10 may be configured not to transmit signals belonging to a plurality of hierarchies.

  As shown in FIG. 1, the transmission apparatus 10 according to the present embodiment includes a layer division unit 10A, an energy spreading unit 10B, an error correction coding unit 10C, a bit interleaving unit 10D, a mapping unit 10E, and a time interleaving. Unit 10F, layer synthesis unit 10G, OFDM frame configuration unit 10H, IFFT (Inverse FFT) unit 10I, GI addition unit 10J, orthogonal modulation unit 10K, and transmission unit 10L.

  The hierarchy dividing unit 10A is configured to divide an input TS (Transport Stream) signal into data belonging to each hierarchy. In the example of FIG. 1, the hierarchy dividing unit 10A is configured to divide the input TS signal into signals belonging to the A layer to the C layer.

  Here, the energy spreading unit 10B, the error correction coding unit 10C, the bit interleaving unit 10D, the mapping unit 10E, and the time interleaving unit 10F are configured to be provided for each layer.

  The energy spreading unit 10B is configured to perform energy spreading processing on a signal for each layer input from the layer dividing unit 10A in order to avoid a situation in which only a specific frequency component becomes large. . For example, the energy spreading unit 10B is configured to perform a process of calculating an exclusive OR between the signal for each layer input from the layer dividing unit 10A and the pseudo random signal.

  The error correction encoding unit 10C is configured to perform error correction encoding processing on the signal for each layer input from the energy spreading unit 10B. For example, the error correction encoding unit 10C is configured to perform FEC (Forward Error Correction) processing on a signal for each layer input from the energy spreading unit 10B.

  The bit interleaving unit 10D is configured to perform bit interleaving processing on the signals for each layer input from the error correction coding unit 10C.

  The mapping unit 10E is configured to perform mapping processing (carrier modulation processing) on the signal for each layer input from the bit interleaving unit 10D. For example, the mapping unit 10E is configured to generate a carrier symbol by mapping a signal for each layer input from the bit interleaving unit 10D to an IQ plane and performing carrier modulation processing.

  The time interleaving unit 10F is configured to perform time interleaving processing on a signal (carrier symbol) for each layer input from the mapping unit 10E.

  The hierarchy synthesizing unit 10G is configured to synthesize signals for each hierarchy input from the time interleaving units 10F.

  The OFDM frame configuration unit 10H is configured to configure an OFDM frame corresponding to the signal input from the layer synthesis unit 10G.

  Specifically, the OFDM frame configuration unit 10H is configured to generate an OFDM frame for the signal input from the hierarchical synthesis unit 10G based on the input OFDM frame configuration information.

  Here, the OFDM frame configuration information includes the segment bandwidth Bws, the FFT size, and the like. Alternatively, the OFDM frame configuration information may include the number of symbols per OFDM frame instead of the segment bandwidth Bws.

  As shown in FIGS. 3 and 4, the length of the OFDM frame generated by the OFDM frame configuration unit 10H is configured to be a fixed length defined for each added gart interval length GI. Yes.

  FIG. 3 shows an example of an OFDM frame configuration of the next generation terrestrial broadcasting system per segment, and FIG. 4 shows an example of an OFDM frame configuration of the next generation terrestrial broadcasting system per channel (6 MHz). For example, the OFDM frame configuration unit 10H adjusts the number of symbols per OFDM frame and the number of carriers C per segment based on the input segment bandwidth Bws and FFT size, and adds the length of the OFDM frame. It is configured to have a fixed length defined for each gart interval length GI.

  Here, as shown in FIGS. 3 and 4, the OFDM frame length when the added gart interval length GI is 1/8 is 290.304 ms, and the OFDM in mode 3 of the current ISDB-T system is used. This is a value equivalent to the frame length of 231.336 ms.

  According to such a configuration, compared with the OFDM frame configuration in the current ISDB-T system, there is no delay in synchronization establishment or channel switching due to an increase in the OFDM frame length, and the convenience of the viewer is deteriorated. Can be avoided.

  The IFFT unit 10I is configured to perform IFFT processing on the signal input from the OFDM frame configuration unit 10H.

  The GI adding unit 10J is configured to add a guard interval GI to the signal input from the IFFT unit 10I.

  The quadrature modulation unit 10K is configured to generate a transmission signal by performing quadrature modulation processing on the signal input from the GI addition unit 10J.

  The transmission unit 10L is configured to transmit a signal (transmission signal) input from the quadrature modulation unit 10K via one or a plurality of transmission antennas.

  As shown in FIG. 2, the receiving apparatus 30 according to the present embodiment includes a receiving unit 30A, an orthogonal demodulating unit 30B, a GI removing unit 30C, a detecting unit 30D, an FFT unit 30E, and a signal demodulating unit 30F. It has.

  The receiving unit 30A is configured to receive a transmission signal transmitted by the transmission device 10 via one or a plurality of reception antennas.

  The orthogonal demodulator 30B is configured to perform orthogonal modulation processing on the signal input from the receiver 30A.

  The GI removal unit 30C is configured to remove the guard interval GI from the signal input from the orthogonal demodulation unit 30B.

  The detection unit 30D is configured to detect the segment bandwidth Bws and the FFT size from the signal input from the GI removal unit 30C.

  For example, the detection unit 30D may be configured to detect the FFT size being used by measuring the carrier interval in the above signal.

  The FFT unit 30E is configured to perform an FFT process on the signal input from the detection unit 30D based on the FFT size detected by the detection unit 30D.

  The signal demodulator 30E performs a demodulation process on the signal input from the FFT unit 30E based on the number of OFDM symbols per OFDM frame corresponding to the combination of the segment bandwidth Bws and the FFT size detected by the detector 30D. It is configured to apply.

  For example, the demodulation process is a process reverse to the process (energy conversion process, error correction encoding process, bit interleave process, mapping process, and time interleave process) performed by the transmission apparatus 10 illustrated in FIG.

  Of the functions of the receiving device 30 shown in FIG. 2, all or part of the quadrature demodulator 30B, GI remover 30C, detector 30D, FFT unit 30E, and signal demodulator 30F may be included in the chip. Good.

  In addition, the digital broadcasting system according to the present embodiment includes a plurality of transmission apparatuses 10, and the length of the OFDM frame generated by each of the plurality of transmission apparatuses 10 is the same as the added gart interval length. In some cases, they may be configured to be the same.

  Here, in each configuration of the OFDM frame, the segment bandwidth Bws, the FFT size, and the like may be configured to be variable.

  The characteristics of the present embodiment described above may be expressed as follows.

  A first feature of the present embodiment is a transmitting apparatus 10, which is configured to generate an OFDM frame corresponding to an input signal based on the input segment bandwidth Bws and the FFT size. A frame configuration unit 10H, and a transmission unit 10L configured to transmit a transmission signal generated by performing predetermined processing on the generated OFDM frame, and the OFDM frame configuration unit 10H The summary is that the length of the generated OFDM frame is configured to be a fixed length defined for each added gart interval length.

  A second feature of the present embodiment is the receiving device 30, and a detection unit 30 </ b> C configured to detect the segment bandwidth Bws and the FFT size from the transmission signal transmitted by the transmitting device 10, and detection Based on the FFT size, the FFT unit 30D configured to perform FFT processing on the input signal, and OFDM per OFDM frame corresponding to the combination of the detected segment bandwidth Bws and FFT size The gist of the present invention is to include a signal demodulator 30E configured to demodulate an input signal based on the number of symbols.

  A third feature of the present embodiment is a chip mounted on the receiving device 30, which is configured to detect the segment bandwidth Bws and the FFT size from the transmission signal transmitted by the transmitting device 10. Corresponds to the combination of the detected segment bandwidth Bws and the FFT size, and the FFT unit 30D configured to perform FFT processing on the input signal based on the detected FFT size The gist of the present invention is to include a signal demodulator 30E configured to perform demodulation processing on an input signal based on the number of OFDM symbols per OFDM frame.

  According to the above configuration, in the next-generation terrestrial broadcasting system, even when the number of carriers C per segment due to the increase in FFT size is increased or the segment bandwidth Bws is reduced, synchronization establishment or viewing is possible. It is possible to avoid a situation where it takes time to switch channels and the convenience of the viewer is deteriorated.

  A fourth feature of the present embodiment is a digital broadcasting system including a plurality of transmission devices 10, and the length of an OFDM frame generated by each of the plurality of transmission devices 10 is determined by the added gart interval length. In the case of being identical, they are configured to be the same, and the gist is that the segment bandwidth Bws and the FFT size are configured to be variable in each configuration of the OFDM frame.

  According to this configuration, since the OFDM frame length used in each broadcasting station provided with the next-generation terrestrial broadcasting transmission device 10 can be made the same, the channel switching time in all the broadcasting stations is made the same. It is possible to improve the convenience of the viewer even during the channel zapping operation.

  Although the present invention has been described in detail using the above-described embodiments, it is obvious to those skilled in the art that the present invention is not limited to the embodiments described in this specification. The present invention can be implemented as modified and changed modes without departing from the spirit and scope of the present invention defined by the description of the scope of claims. Therefore, the description of the present specification is for illustrative purposes and does not have any limiting meaning to the present invention.

DESCRIPTION OF SYMBOLS 10 ... Transmitting apparatus 10A ... Hierarchical division part 10B ... Energy spreading | diffusion part 10C ... Error correction encoding part 10D ... Bit interleaving part 10E ... Mapping part 10F ... Time interleaving part 10G ... Hierarchical synthesis part 10H ... OFDM frame structure part 10I ... IFFT part 10J: GI adding unit 10K ... orthogonal modulation unit 10L ... transmitting unit 30 ... receiving device 30A ... receiving unit 30B ... orthogonal demodulating unit 30C ... GI removing unit 30D ... detecting unit 30E ... FFT unit 30F ... signal demodulating unit

Claims (1)

A transmitting device,
An OFDM frame configuration unit configured to generate an OFDM frame corresponding to the input signal based on the input segment bandwidth and the FFT size;
A transmission unit configured to transmit a transmission signal generated by performing predetermined processing on the generated OFDM frame, and
The transmission apparatus according to claim 1, wherein a length of the OFDM frame generated by the OFDM frame configuration unit is a fixed length defined for each added gart interval length.

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