Transmitter and receiver

Abstract

To improve time interleaving effect in TDM without increasing transmission delay.SOLUTION: A transmitter used in a broadcasting system that performs layered transmission includes: time division multiplexing means for multiplexing signals of a plurality of layers within a frame by time division multiplexing; and transmission means for transmitting the multiplexed signals multiplexed by the time division multiplexing means. The time division multiplexing means divides each of a plurality of sub-frames associated with the plurality of layers into a plurality of blocks in a time direction, and disperses and arranges the plurality of blocks within the time direction in the frame.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present invention relates to a transmitting apparatus and a receiving apparatus for use in a broadcasting system.

Background Art

[0002] Towards higher quality and enhanced functionality of terrestrial digital broadcasting, studies are underway on a next-generation terrestrial broadcasting transmission scheme (hereinafter referred to as the "advanced terrestrial broadcasting scheme") that inherits the features of the current ISDB-T (Integrated Services Digital Broadcasting-Terrestrial) scheme specified in Non-Patent Document 1 (see, for example, Patent Document 1 and Non-Patent Document 2).

[0003] In ISDB-T, hierarchical transmission provides mobile reception services and fixed reception services simultaneously on a single channel. In the advanced terrestrial broadcasting scheme as well, it is assumed that a plurality of services and content will be transmitted within a single channel via hierarchical transmission.

[0004] Here, ISDB-T enables hierarchical transmission based on frequency division multiplexing (FDM). Specifically, hierarchical transmission is realized by dividing the transmission band of one channel into 13 segments and allocating segments for mobile reception and fixed reception respectively. By setting the mobile reception layer to the central 1 segment, narrowband reception can be performed, which is advantageous for the receiving apparatus as it enables power-saving reception.

[0005] On the other hand, European and American broadcasting standards such as DVB-T2 and ATSC (Advanced Television Systems Committee) 3.0 enable hierarchical transmission based on time-division multiplexing (TDM). Specifically, the hierarchy can be divided into OFDM symbol units, and multiple subframes, such as mobile reception subframes and fixed reception subframes, can be provided (see, for example, Non-Patent Document 3). In the case of TDM, the FFT (Fast Fourier Transform) size can be changed for each subframe, making it possible to set the optimal FFT size according to the service.

[0006] Furthermore, broadcast systems need to transmit control information such as transmission parameters in addition to mainline signals such as content. In ISDB-T, which is based on FDM, a specific OFDM subcarrier is allocated for the transmission of control information, and this control information is transmitted on a frame-by-frame basis. In the case of ISDB-T, this corresponds to the TMCC (Transmission and Multiplexing Configuration and Control) signal. On the other hand, in DVB-T2 and ATSC3.0, which are based on TDM, control information is transmitted using the first few symbols of the frame. In ATSC3.0, this corresponds to the bootstrap and preamble signals. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2018-198426 [Non-patent literature]

[0008] [Non-Patent Document 1] ARIB STD-B31 (Association of Radio Industries and Businesses) [Non-Patent Document 2] NHK R&D No. 172, pp. 2-47, November 2018. [Non-Patent Document 3] ATSC 3.0 Standard:Physical Layer Protocol A / 322:2020 P245-249, https: / / www.atsc.org / wp-content / uploads / 2020 / 01 / A322-2020-Physical-Layer-Protocol.pdf [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] When using TDM as the multiplexing method in broadcast systems, the effect of time interleaving is smaller compared to when using FDM. This effect is particularly pronounced when the proportion of mobile receiver subframes to the total signal is small. Increasing the time interleaving length can mitigate this effect, but increasing the interleaving length comes with an increase in transmission delay.

[0010] Therefore, the present invention aims to provide a transmitting device and a receiving device that improve the time interleaving effect in TDM without increasing transmission delay. [Means for solving the problem]

[0011] The first embodiment of the transmitting device is a transmitting device used in a broadcasting system that performs hierarchical transmission, and comprises a time-division multiplexing means for multiplexing signals of multiple layers within a frame by time-division multiplexing, and a transmitting means for transmitting the multiplexed signals multiplexed by the time-division multiplexing means. The time-division multiplexing means divides each of the multiple subframes associated with the multiple layers into multiple blocks in the time direction, and arranges the multiple blocks distributed in the time direction within the frame.

[0012] A receiving device according to a second embodiment is a receiving device used in a broadcasting system that performs hierarchical transmission, comprising: receiving means for receiving a multiplexed signal obtained by multiplexing signals of multiple hierarchical levels within a frame by time division multiplexing from a transmitting device; and time division multiplexing separation means for separating a plurality of blocks obtained by dividing each of a plurality of subframes associated with the plurality of hierarchical levels in the time direction, the plurality of blocks which are distributed in the time direction within the frame, from the multiplexed signal. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a transmitting device and a receiving device that improve the time interleaving effect in TDM without increasing transmission delay. [Brief explanation of the drawing]

[0014] [Figure 1] This figure shows the transmission bandwidth in the broadcasting system according to the embodiment. [Figure 2] This diagram shows the characteristics of TDM and FDM, respectively. [Figure 3] This figure shows a schematic configuration of the broadcasting system according to the embodiment. [Figure 4] This figure shows examples of signal configurations when TDM and FDM configurations are used for the signal configuration of hierarchical signals. [Figure 5] This figure shows an example of a signal configuration when a combination of FDM and TDM is used for the signal configuration of a hierarchical signal. [Figure 6] This figure shows an example of a signal configuration when using frame boundary pilots. [Figure 7] This figure shows the operation in the intermittent reception ON mode according to the embodiment. [Figure 8] This figure shows the operation in the intermittent reception off mode according to the embodiment. [Figure 9] This figure shows the operation in the intermittent reception off mode according to the embodiment. [Figure 10] This figure shows the operation in the intermittent reception off mode according to the embodiment. [Figure 11] This is a diagram illustrating the operation in the intermittent reception off mode according to the embodiment. [Figure 12] This is a diagram illustrating the operation in the intermittent reception off mode according to the embodiment. [Figure 13] This is a diagram illustrating an example of the transmission apparatus according to the embodiment. [Figure 14] This is a diagram illustrating an example of the reception apparatus according to the embodiment. [Figure 15] This is a diagram for explaining the effects of the embodiment. [Figure 16] This is a diagram for explaining the effects of the embodiment. [Modes for Carrying Out the Invention]

[0015] The embodiment will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

[0016] (1) Broadcast System First, the broadcast system according to the present embodiment will be described with reference to FIG. 1 to FIG. 3. The broadcast system according to the present embodiment is a system compatible with the advanced terrestrial broadcasting scheme, and is a terrestrial digital television broadcast system that performs hierarchical transmission.

[0017] (1.1) Transmission Band in Broadcast System The transmission band in the broadcast system according to the present embodiment will be described with reference to FIG. 1. In the present embodiment, the total bandwidth of one channel is assumed to be 6 MHz.

[0018] As shown in Figure 1(a), ISDB-T divides the transmission bandwidth of one channel (5.57 MHz) into 13 segments in the frequency direction. Of these, the central segment is allocated as a partial reception band α for mobile reception services, and the remaining 12 segments are allocated as a non-partial reception band β for fixed reception services. Receiving equipment for mobile reception (i.e., mobile devices) can perform power-saving reception through narrowband reception by setting the mobile reception layer to the central segment.

[0019] Here, the mobile reception layer is the layer to which transmission parameters with higher transmission tolerance (e.g., carrier modulation scheme, coding rate) are applied compared to the fixed reception layer. The fixed reception layer is the layer to which transmission parameters with lower transmission tolerance are applied compared to the mobile reception layer, and is the layer for transmitting higher-quality video compared to the mobile reception layer. The mobile reception layer is sometimes called layer A, and the fixed reception layer is sometimes called layer B. Below, we will describe an example that supports layered transmission with up to three layers (layer A, layer B, and layer C), and in which different transmission parameters can be set for each layer.

[0020] Figures 1(b) and (c) show the transmission bandwidth of the advanced terrestrial broadcasting system. In the advanced terrestrial broadcasting system, compared to ISDB-T, the transmission bandwidth is divided into many segments, and the bitrate of each layer is being considered to be adjusted more finely. As shown in Figure 1(b), in the compatibility mode of the advanced terrestrial broadcasting system, the bandwidth of one channel is 5.57 MHz, the same as ISDB-T. The number of segments within the transmission bandwidth is, for example, 33, and the parts at both ends of the transmission bandwidth are adjustment bandwidths γ. As shown in Figure 1(c), in the normal mode of the advanced terrestrial broadcasting system, the transmission bandwidth is expanded compared to ISDB-T, for example, to a transmission bandwidth of 5.83 MHz. The number of segments within the transmission bandwidth is, for example, 35. In both the compatibility mode and the normal mode, the partial reception bandwidth α can be the bandwidth of the central 1 to 9 segments, and the rest can be the non-partial reception bandwidth β.

[0021] Thus, in the advanced terrestrial broadcasting system, multiple bandwidths are defined as the bandwidth corresponding to a single channel. Furthermore, the advanced terrestrial broadcasting system is expected to inherit the features of ISDB-T and perform hierarchical transmission based on FDM. However, FDM has some drawbacks compared to TDM. Therefore, the broadcasting system according to this embodiment is a broadcasting system that can support both TDM and FDM multiplexing methods.

[0022] (1.2) Overview of the multiplexing method Refer to Figure 2 to explain the characteristics of TDM and FDM.

[0023] Regarding synchronization performance, TDM enables short-time signal detection and various types of synchronization (frequency synchronization, symbol synchronization, frame synchronization) using a preamble signal at the beginning of the frame (signal start). In contrast, FDM uses a TMCC signal assigned to a specific subcarrier (hereinafter also simply referred to as "carrier"), so synchronization requires at least one frame's worth of signal. Therefore, TDM is superior to FDM in terms of synchronization performance regarding initial signal detection. Accordingly, in this embodiment, a broadcasting method is adopted that takes advantage of the benefits of TDM by placing the preamble signal at the beginning of the frame. Furthermore, in this embodiment, a TMCC signal is placed at a time position following the preamble signal, and the transmission parameters of subsequent subframes and layers are notified to the receiving device by the TMCC signal.

[0024] Regarding the flexibility of signal multiplexing, TDM allows for the selection of appropriate FFT sizes for mobile and fixed reception, offering greater parameter flexibility. The FFT size refers to the number of FFT samples used in the modulation and demodulation processing of OFDM (Orthogonal Frequency Division Multiplexing) signals. For example, an FFT size of 8192 is denoted as 8kFFT. For instance, 8kFFT can be used for mobile reception and 32kFFT for fixed reception. In contrast, FDM requires the use of the same FFT size (e.g., 16kFFT) for both mobile and fixed reception. Therefore, TDM is superior to FDM in terms of signal multiplexing flexibility. Accordingly, this embodiment utilizes the advantages of TDM by dividing a frame into multiple subframes and allowing the FFT size to be set individually for each subframe.

[0025] Regarding power saving, TDM can achieve power savings by using a time-partial receiver on the receiving device side and switching the receiver (RF circuit) on and off. This intermittent reception operation is sometimes called intermittent reception. In contrast, FDM uses a frequency-partial receiver on the receiving device side and performs narrowband reception. Power saving is possible by narrowing the bandwidth. Therefore, it can be said that the power saving performance of TDM and FDM is equivalent. In this embodiment, a broadcasting system that can use both TDM and FDM can be used in combination. This makes it possible to use both time-partial reception and frequency-partial reception in combination, achieving further power savings.

[0026] Regarding scalability, TDM allows for easy addition of subframes and easy introduction of signals for new services. In contrast, FDM is relatively difficult to expand. Therefore, TDM is superior to FDM in terms of scalability. Thus, in this embodiment, it is possible to introduce expansion frames by adding subframes that transmit signals for new services, thereby utilizing the advantages of TDM as a broadcasting method.

[0027] Regarding multipath characteristics, TDM is robust against frequency-selective fading because the receiving device receives over a wide bandwidth (i.e., frequency interleaving is highly effective). In contrast, FDM can receive over a wide bandwidth in the fixed receiving layer, but it receives over a narrow bandwidth in the mobile receiving layer, resulting in weaker resistance (i.e., frequency interleaving is less effective in narrowband reception). Therefore, TDM is superior to FDM in terms of multipath characteristics.

[0028] Regarding speed tolerance, at low speeds, TDM has intermittent signals in the time direction, making it difficult to achieve the benefits of time interleaving, while FDM has continuous signals in the time direction, resulting in a high benefit of time interleaving. Therefore, FDM is superior to TDM in terms of speed tolerance at low speeds. Thus, for services associated with low-speed movement, it may be possible to configure the system to allow the occupancy of specific segments, thereby leveraging the advantages of FDM. Furthermore, regarding speed tolerance at high speeds, TDM can use an FFT size suitable for mobile reception. In FDM, the characteristics depend on the FFT size used.

[0029] Thus, FDM and TDM each have different advantages, and the optimal multiplexing method varies depending on the service requirements. In this embodiment, the broadcasting system is designed to allow the application of the optimal multiplexing method according to the service requirements. Specifically, by providing a broadcasting system that allows the selection of either TDM or FDM multiplexing methods, broadcasters can select the optimal signal multiplexing method according to the service.

[0030] Furthermore, this embodiment employs a signal configuration that allows for the continuous multiplexing of multiple subframes in the time direction using TDM. Within each subframe, a signal configuration that allows for hierarchical division and multiplexing at the segment level, similar to FDM, may be used. However, it may also be possible to support signal multiplexing like TDM using multiple subframes, or like FDM using multiple layers in a single subframe. It may also be possible to configure only specific subframes to be hierarchically divided using FDM.

[0031] (1.3) Outline of the broadcasting system Referring to Figure 3, the schematic configuration of the broadcasting system 1 according to this embodiment will be described. The broadcasting system 1 includes a transmitting device 100 and a receiving device 200. The receiving device 200 may include multiple types of receiving devices 200, including those for fixed reception.

[0032] (1.3.1) Schematic configuration of the transmitting device The transmitting device 100 includes a control signal generation means 101, a hierarchical signal generation means 102, a multiplexing means 103, and a transmitting means 104.

[0033] The control signal generation means 101 generates control signals used for at least one of synchronization and control in broadcast transmission and outputs the generated control signals. The control signal generation means 101 includes a preamble signal generation unit 110 that generates a preamble signal among the control signals, and a TMCC signal generation unit 120 that generates a TMCC signal among the control signals. The preamble signal is a signal placed at the beginning of a frame. The preamble signal is a signal used by the receiving device 200 to establish synchronization. The preamble signal is configured to include information necessary for the receiving device 200 to receive the TMCC signal. The TMCC signal is a signal that follows the preamble signal, that is, a signal placed in the time interval after the beginning of the frame. The TMCC signal is a signal used for control in broadcast transmission and is configured to include TMCC information necessary for the receiving device 200 to receive the hierarchical signal.

[0034] The control signal generation means 101 may generate a control signal that includes information indicating whether or not partial reception using a partial reception band (i.e., narrowband reception) is enabled. This makes it possible to turn partial reception on or off. For example, a partial reception flag is transmitted by a preamble signal. This allows intermittent and partial reception to be performed only for layers within a specific subframe, which is effective in reducing the power consumption of the receiver.

[0035] The control signal generation means 101 may generate a control signal that includes information indicating the number of subframes in a frame and information indicating the number of layers within each subframe. For example, subframes can be specified in units of the number of symbols, and layers can be specified in units of the number of carriers or segments. By including information indicating the number of subframes in a frame and information indicating the number of layers within each subframe in the control signal, the receiving device 200 can appropriately receive signals from each layer within each subframe based on the control signal. The control signal generation means 101 may also generate a control signal that includes information indicating the FFT size specified for each subframe and information indicating the carrier modulation scheme and coding rate specified for each layer within each subframe. Since the FFT size and guard interval length can be specified for each subframe, signal multiplexing with different OFDM symbol lengths is possible. Furthermore, for layers, the carrier modulation scheme and coding rate can be variably set while the FFT size and guard interval length remain constant. For example, the TMCC signal includes transmission parameters related to the subsequent signal configuration, such as transmission mode (SISO, MISO, MIMO), number of subframes, number of layers within a subframe, number of subframe symbols, number of segments in each layer, number of modulation levels in each layer (carrier modulation scheme), time interleave length, and coding rate.

[0036] The control signal generation means 101 may generate a control signal that includes information indicating that a subframe is an extension frame, if a subframe to be used as an extension frame is provided. This makes it easier to expand the service by taking advantage of the benefits of TDM. For example, the length of the extension frame is specified by a preamble signal or a TMCC signal. A receiving device 200 that does not support the extension frame signal can receive normal subframes while ignoring the extension frame.

[0037] The control signal generation means 101 may generate a control signal that includes information specifying one of SISO transmission, MIMO transmission, or MISO transmission for each layer or subframe. This allows the transmission mode to be variably set for each layer or subframe.

[0038] The hierarchical signal generation means 102 generates signals of multiple layers, each associated with a different service. For example, the services include mobile reception services and fixed reception services. The services may also include voice services and video services. In this embodiment, the hierarchical signal generation means 102 generates signals of two layers (layer A, layer B) or three layers (layer A, layer B, layer C). The hierarchical signal generation means 102 can set different transmission parameters (e.g., carrier modulation scheme, coding rate) for each layer in the signal.

[0039] The multiplexing means 103 multiplexes the preamble signal generated by the preamble signal generation unit 110, the TMCC signal generated by the TMCC signal generation unit 120, and the signals of multiple layers generated by the layer signal generation means 102, and outputs a multiplexed signal. The multiplexing means 103 includes an FDM means (frequency division multiplexing means) 103a that multiplexes signals of two or more layers included in the multiple layers using FDM within the transmission bandwidth of one channel, and a TDM means (time division multiplexing means) 103b that multiplexes signals of two or more layers included in the multiple layers using time division multiplexing within one frame. Because the multiplexing means 103 has both the FDM means 103a and the TDM means 103b, the transmitting device 100 used in the broadcasting system 1 can support both FDM and TDM, and broadcasters can apply the optimal multiplexing method according to the service requirements.

[0040] In this embodiment, the TDM means 103b performs TDM by dividing a frame into multiple subframes in the time direction. The FDM means 103a performs FDM by dividing the channel transmission bandwidth into two or more layers of segments in the frequency direction in at least one subframe. By dividing a frame into subframes in the time direction and dividing each subframe into two or more layers of segments in the frequency direction, it becomes possible to combine TDM and FDM. This enables efficient broadcast transmission by taking advantage of the respective benefits of TDM and FDM.

[0041] The TDM means 103b places a control signal in the first time interval of the frame (i.e., the beginning portion of the frame). By placing the control signal used for synchronization and control of broadcast transmission in the first time interval of the frame, the receiving device 200 can establish synchronization early at the beginning of the frame.

[0042] The FDM means 103a may place a segment of a specific layer (e.g., layer A) associated with a mobile receiving service within a subframe containing that specific layer segment within a partial receiving band of the transmission band. This enables partial reception using FDM, such as ISDB-T, even while using TDM. The FDM means 103a may also place a TMCC signal associated with a mobile receiving service within a partial receiving band. This enables partial reception of the TMCC signal.

[0043] The TDM means 103b may multiplex at least one subframe containing signals of multiple layers and a subframe used as an extension frame using TDM. This makes it easier to expand the service by taking advantage of the benefits of TDM.

[0044] The transmitting means 104 transmits the multiplexed signal, which has been multiplexed by the multiplexing means 103, via broadcast waves. The transmitting means 104 may perform single-antenna transmission using one transmitting antenna, or multiple-antenna transmission using two or more transmitting antennas. In this embodiment, the transmitting means 104 is assumed to support multiple-antenna transmission using two transmitting antennas, with the transmission system associated with one transmitting antenna being called "system 1" and the transmission system associated with the other transmitting antenna being called "system 2". Therefore, the broadcast system 1 can support various transmission methods such as SISO (Single-Input Single-Output), MISO (Multiple-Input Single-Output), MIMO (Multiple-Input Multiple-Output), SFBC (Space-Frequency Block Code), STBC (Space-Time Block Code), and SDM (Space Division Multiplexing). In STBC, two data symbols are paired in the time direction, and the complex conjugate and sign inversion of the data carrier symbol are performed. Furthermore, SFBC performs complex conjugate and sign inversion of the data carrier symbol by pairing two data symbols in the frequency direction.

[0045] (1.3.2) Schematic configuration of the receiving device The receiving device 200 includes a receiving means 201, a control signal processing means 202, a multiplexing means 203, and a hierarchical signal processing means 204.

[0046] The receiving means 201 receives a multiplexed signal from the transmitting device 100 via broadcast waves and outputs a received signal, which is the received multiplexed signal. In the time direction, the multiplexed signal is multiplexed by TDM, consisting of a preamble signal placed at the beginning of the frame, a TMCC signal placed in the time interval after the preamble signal, and one or more subframe signals placed after the TMCC signal. Each subframe may be multiplexed by FDM, consisting of one or more layers of signals in the frequency direction. The receiving means 201 may perform single-antenna reception using one receiving antenna, or multiple-antenna reception using two or more receiving antennas.

[0047] The control signal processing means 202 processes the control signals included in the received signal. The control signal processing means 202 includes a preamble signal processing unit 32 that processes the preamble signal among the control signals, and a TMCC signal processing unit 33 that processes the TMCC signal among the control signals. The preamble signal processing unit 32 establishes synchronization based on the preamble signal. The preamble signal processing unit 32 also demodulates the preamble signal and, based on the information transmitted in the preamble signal, identifies transmission parameters for receiving and processing the TMCC signal and outputs the identified transmission parameters. The TMCC signal processing unit 33 demodulates and decodes the TMCC signal based on the transmission parameters identified by the preamble signal processing unit 32, identifies transmission parameters for receiving and processing the hierarchical signal based on the TMCC information transmitted in the TMCC signal, and outputs the identified transmission parameters.

[0048] The multiplexing / decoupling means 203 multiplexes and decouples multiple layers of signals from the received signal (multiplexed signal) based on the transmission parameters output by the TMCC signal processing unit 33, and outputs one or more layers of signals associated with the selected service. The multiplexing / decoupling means 203 includes a TDM decoupling means (time-division multiplexing / decoupling means) 203a that decouples layers of signals multiplexed by TDM within one frame, and an FDM decoupling means (frequency-division multiplexing / decoupling means) 203b that decouples layers of signals multiplexed by FDM within the transmission bandwidth of one channel. Specifically, the TDM decoupling means 203a extracts a target subframe containing the layer of signals associated with the selected service. The FDM decoupling means 203b acquires the signal of that layer from the target subframe extracted by the TDM decoupling means 203a and outputs the acquired layer of signals.

[0049] The hierarchical signal processing means 204 processes (demodulates and decodes) the hierarchical signal output by the multiplexing / decoupling means 203 based on the transmission parameters output by the TMCC signal processing unit 33 to acquire hierarchical data (e.g., video data), and outputs the acquired hierarchical data.

[0050] (2) An example of a signal configuration An example of a signal configuration according to this embodiment will be described with reference to Figures 4 to 6.

[0051] (2.1) TDM configuration and FDM configuration Referring to Figure 4, examples of signal configurations using TDM and FDM configurations for hierarchical signals will be explained. Figure 4(a) shows an example of a signal configuration using a TDM configuration for hierarchical signals, and Figure 4(b) shows an example of a signal configuration using an FDM configuration for hierarchical signals. Note that the bandwidth of the transmission band may be in normal mode or compatible mode.

[0052] As shown in Figure 4(a), the transmitter 100 arranges the preamble signal, TMCC signal, and hierarchical signal using TDM. When the number of subframes in a frame is "2" and the number of hierarchical levels within each subframe is "1", the signal configuration is as shown in Figure 4(a). The beginning of the frame where the preamble signal is placed consists of multiple symbol sections (four symbols in the example in Figure 4). The time section where the TMCC signal is placed is immediately after the preamble signal, and the first symbol section of the TMCC signal is consecutive with the last symbol section of the preamble signal. In the example in Figure 4, the time section where the TMCC signal is placed consists of two symbol sections. For example, the subframe immediately following the TMCC signal is subframe #1, and the A-hierarchical signal is placed in this subframe. The subframe immediately following subframe #1 is subframe #2, and the B-hierarchical signal is placed in this subframe. Each of subframes #1 and #2 consists of multiple symbol sections. If the FFT size and guard interval length are set differently for subframe #1 and subframe #2, the symbol lengths of subframe #1 and subframe #2 will differ from each other. In the example shown in Figure 4(a), the time length of each symbol interval constituting subframe #1 is shorter than the time length of each symbol interval constituting subframe #2.

[0053] Within a frame, the time domain consisting of the preamble section and the TMCC section may be called the control domain. Within a frame, the time domain other than the control domain, i.e., the region in which one or more subframes are located, may be called the data domain.

[0054] As shown in Figure 4(b), even when FDM arrangement is used for the signal configuration of the hierarchical signals, the signal configuration of the preamble signal and TMCC signal is the same as in Figure 4(a). When the number of subframes in a frame is set to "1" and the number of hierarchical levels within each subframe is set to "2", the signal configuration is as shown in Figure 4(b). Each hierarchical level consists of one or more segments. Each hierarchical level may also be specified in units of less than one segment (e.g., 1 / 3 of a segment).

[0055] Referring to Figure 5, we will explain an example of a signal configuration using a combination of FDM and TDM for the hierarchical signal configuration, focusing on the differences from Figure 4.

[0056] If the number of subframes within a frame is set to "2", the number of layers in the first subframe #1 is set to "2", and the number of layers in the other subframe #2 is set to "1", the signal configuration will be as shown in Figure 5. The signal configurations of the preamble signal and TMCC signal are the same as in Figure 4.

[0057] For example, subframe #1 could be a layer designed for mobile reception, and subframe #2 a service layer designed for fixed reception. Subframe #1 could contain audio-only content in layer A, and video-only content in layer B, for instance. This configuration is effective when you want to ensure high resilience only for audio services received by mobile devices.

[0058] (2.2) Frame boundary pilot Referring to Figure 6, an example of a signal configuration using a frame boundary pilot will be explained.

[0059] The transmitter 100 may place frame boundary SPs (Scattered Pilots) for the first and last symbols within a subframe. Frame boundary SPs may have a higher pilot density than normal SPs. When a signal is composed of multiple subframes, transmission path estimation at the subframe boundaries can become complex; therefore, inserting frame boundary SPs can improve the accuracy of transmission path estimation at the frame boundaries. Whether or not to include frame boundary SPs can be specified by the TMCC signal. The placement of normal SPs can also be specified by the TMCC signal. Parameters related to SPs may be specified for each layer within the subframe. Furthermore, by setting the boost ratio of SPs inserted as frame boundary SPs to 1, the power allocated to the data carrier between symbols can be kept constant.

[0060] In the signal configuration example shown in Figure 6, the number of symbols constituting a subframe is "11". The transmitting device 100 notifies the receiving device 200 of the number of symbols constituting the subframe, "11", based on the TMCC information for each subframe in the TMCC signal. Also, in the signal configuration example shown in Figure 6, a normal SP has a frequency-direction spacing (Dx) of "3" and a time-direction spacing (Dy) of "4". A frame boundary SP has a time-direction spacing (Dy) of "1".

[0061] (3) Operation in TDM The operation of TDM according to this embodiment will be described with reference to Figures 7 to 12.

[0062] (3.1) Intermittent reception ON mode Referring to Figure 7, the operation in the intermittent reception ON mode according to this embodiment will be described. The intermittent reception ON mode is a TDM mode (first mode) that uses the signal configuration of the TDM arrangement described above.

[0063] As shown in Figure 7(a), in intermittent reception ON mode, the TDM means 103b of the transmitter 100 arranges hierarchical signals in units of subframes. For example, the subframe immediately following the TMCC signal is subframe #1, and the A-hierarchical (mobile reception hierarchical) signal is placed in this subframe. The subframe immediately following subframe #1 is subframe #2, and the B-hierarchical (fixed reception hierarchical) signal is placed in this subframe.

[0064] In the example in Figure 7(a), subframe #1, associated with layer A (mobile receiving layer), has an FFT size of 8kFFT and 12 symbols. In contrast, subframe #2, associated with layer B (fixed receiving layer), has an FFT size of 32kFFT and 48 symbols.

[0065] As shown in Figure 7(b), the receiving device 200 that receives Layer A (mobile receiving layer) can turn off the power to the receiving means 201 (receiver) during the period of subframe #2, which is associated with Layer B (fixed receiving layer). In other words, the receiving device 200 that receives Layer A (mobile receiving layer) performs receiving operations only during the preamble section, TMCC section, and subframe #1 within the frame, and does not perform receiving operations during subframe #2. This makes it possible to reduce the power consumption of the receiving device 200.

[0066] However, because each subframe has intermittent signals in the time direction, the effect of time interleaving is difficult to obtain. Specifically, if noise is introduced during broadcast transmission or the reception level temporarily drops, errors occur in the layered signals. Errors include sporadic random errors and continuous burst errors, but random errors can be corrected relatively easily with error correction technology. On the other hand, burst errors are difficult to correct as they are. Interleaving is a technology that converts burst errors into random errors, making error correction easier.

[0067] In the example of level fluctuations during mobile reception shown in Figure 7(c), the received level decreases during the period of mobile reception of subframe #1. The receiving device 200, which receives the A layer (mobile reception layer), may experience burst errors in the A layer signal received in subframe #1, leading to a deterioration of its reception characteristics. While this effect can be mitigated by increasing the time interleave length, it results in an increase in transmission delay.

[0068] Therefore, in this embodiment, even when TDM is used as a multiplexing method in the broadcasting system, a new mode (second mode) is introduced that can improve the time interleaving effect. Hereinafter, this new TDM mode will be referred to as the intermittent reception off mode.

[0069] (3.2) Intermittent reception off mode Referring to Figures 8 to 12, the operation in the intermittent reception off mode according to this embodiment will be described. In the intermittent reception off mode, the receiving side (receiving device 200) does not perform intermittent reception.

[0070] (3.2.1) Transmitter operation in intermittent reception off mode As shown in Figure 8(a), in intermittent reception off mode, the TDM means 103b of the transmitting device 100 divides each of the multiple subframes associated with the multiple layers into multiple blocks in the time direction, and arranges these multiple blocks in a time-distributed manner within the frame.

[0071] The multiple layers may include a mobile reception layer and a fixed reception layer. The multiple subframes include a mobile reception subframe #1 associated with the mobile reception layer and a fixed reception subframe #2 associated with the fixed reception layer. Mobile reception subframe #1 has an FFT size of 8kFFT and a total of 12 symbols. In contrast, fixed reception subframe #2 has an FFT size of 32kFFT and a total of 48 symbols.

[0072] The TDM means 103b of the transmitting device 100 divides the mobile receiving subframe #1 into mobile receiving blocks and the fixed receiving subframe #2 into fixed receiving blocks, and arranges the mobile receiving blocks and fixed receiving blocks alternately within the frame.

[0073] Figure 8(a) shows an example where each subframe is divided into blocks with a number of divisions of "3". Therefore, each block belonging to subframe #1 (blocks #1 through #3) has 4 symbols. In other words, in the example with 3 divisions, subframe #1, which consists of a total of 12 symbols, is divided into 3 blocks, each consisting of 4 symbols. Also, each block belonging to subframe #2 (blocks #1 through #3) has 16 symbols. In other words, subframe #2, which consists of a total of 48 symbols, is divided into 3 blocks, each consisting of 16 symbols.

[0074] By using a signal configuration as shown in Figure 8(a), for example, if I=1 (time interleave length = signal length within one frame) is used as the time interleave parameter, the effect can be mitigated even if some signals within a frame are degraded due to a decrease in the received level, as shown in Figure 8(b). Therefore, it is possible to improve the time interleave effect in TDM without increasing the interleave length (without increasing the transmission delay).

[0075] Figure 9 shows an example where each subframe is divided into blocks, with 12 divisions. Therefore, each block belonging to subframe #1 (blocks #1 through #12) has 1 symbol. In other words, in the example with 12 divisions, subframe #1, which consists of 12 symbols in total, is divided into 12 blocks, each consisting of 1 symbol. Similarly, each block belonging to subframe #2 (blocks #1 through #12) has 4 symbols. In other words, subframe #2, which consists of 48 symbols in total, is divided into 12 blocks, each consisting of 4 symbols.

[0076] In intermittent reception off mode, multiple boundaries between subframe #1 and subframe #2 occur. The SP placement at subframe boundaries (specifically, block boundaries) may use densely packed frame boundary SPs (see Figure 6). The on / off status of frame boundary SPs can be specified by TMCC.

[0077] The TDM means 103b of the transmitting device 100 may switch between an intermittent reception on mode, in which multiple subframes are placed within a frame without block division, and an intermittent reception off mode, in which multiple blocks obtained by block division are distributed in the time direction within the frame. The intermittent reception on mode is an example of a first mode in which the receiving side performs intermittent reception by stopping the reception of subframes other than the desired subframe. The intermittent reception on mode is an example of a second mode in which the receiving side does not perform intermittent reception.

[0078] In the receiving device 200 that supports intermittent reception, in intermittent reception ON mode, after demodulating the preamble signal and TMCC signal, the power of the receiving means 201 (receiver) is turned ON only during the period when the signal of the subframe to be received (desired subframe) is being transmitted. Power consumption can be reduced by turning off the power during other times. Such intermittent reception is particularly effective for battery-powered receiving devices 200 such as mobile terminals. On the other hand, in receiving devices 200 with a power supply, such as in-vehicle terminals, it is more effective to turn off intermittent reception to improve reception characteristics. The transmitting device 100 can apply the optimal TDM mode from among the intermittent reception ON mode and intermittent reception OFF mode, for example, according to the service requirements.

[0079] The control signal generation means 101 of the transmitting device 100 generates a control signal that includes at least one of the following: mode information indicating the mode to be applied from among intermittent reception on mode and intermittent reception off mode, and division information indicating the number of divisions when dividing a subframe into blocks. This control signal is a preamble signal placed at the beginning of the frame, or a TMCC signal that follows the preamble signal. For example, the TMCC signal generation unit 120 of the control signal generation means 101 generates and outputs a TMCC signal (TMCC information) that includes at least one of the mode information and division information.

[0080] Here, the mode information may be a 1-bit flag that is a first value (e.g., "0") when intermittent reception is on mode, and a second value (e.g., "1") when intermittent reception is off mode. Alternatively, the division information may function as the mode information. For example, setting a value in the division information that indicates no block division may indicate that intermittent reception is on mode. Furthermore, the division information may not be the number of divisions itself, but a value indicating the number of blocks. The division information may also be information indicating the number of blocks for each subframe.

[0081] Note that while Figures 8 and 9 show examples where the number of divisions is a divisor of the number of symbols in subframes #1 and #2, as shown in Figure 10, other numbers of divisions may also be used. In Figure 10, subframe #1 consists of 14 symbols. If the number of divisions is 3, subframe #1 is divided into two blocks (blocks #1 and #2) consisting of 5 symbols each, and one block (block #3) consisting of 4 symbols each. Also, subframe #2 consists of 49 symbols. If the number of divisions is 3, subframe #2 is divided into one block (block #1) consisting of 17 symbols each, and two blocks (blocks #2 and #3) consisting of 16 symbols each.

[0082] Furthermore, in the examples shown in Figures 8 to 10, each subframe was divided into the same number of blocks, and the blocks of each subframe were arranged alternately to form a frame. However, each subframe may also be divided and arranged by randomization. Specifically, as shown in Figure 11, the TDM means 103b of the transmitting device 100 may divide a plurality of subframes into blocks on a symbol basis, and then arrange each block, which has been rearranged in the time direction using a predetermined randomization method, within the frame.

[0083] Figure 11 shows an example where subframe #1 consists of 12 symbols and subframe #2 consists of 48 symbols. As shown in Figure 11(a), the TDM means 103b of the transmitting device 100 first sums the symbols in each subframe and assigns a symbol number, which becomes the total number of symbols. In the example in Figure 11(a), symbol numbers 0 to 11 are subframe #1, and symbol numbers 12 to 59 are subframe #2, resulting in a total of 60 symbols. Next, as shown in Figure 11(b), the TDM means 103b of the transmitting device 100 rearranges the 60 symbols by randomization. Examples of randomization include a method that uses random numbers (pseudorandom number sequences) to perform the randomization uniquely, or a method that uses a randomization table. The randomization rules, such as the generation formula and randomization table used for generating random numbers, are assumed to be the same rules in advance in both the transmitting device 100 and the receiving device 200.

[0084] For example, a randomized table, as shown in Figure 12, is a table that associates symbol numbers before sorting with symbol numbers after sorting, one symbol at a time. Figure 12 shows an example of preparing a long randomized table that can handle both a total of 120 symbols and a total of 60 symbols. In the case of a total of 60 symbols, symbols up to "59" are used as the symbol numbers before sorting, and values ​​after that are skipped.

[0085] (3.2.2) Operation of the receiving device in intermittent reception off mode In the receiving device 200 according to this embodiment, the receiving means 201 receives a multiplexed signal obtained by multiplexing signals of multiple layers within a frame using TDM from the transmitting device 100. The TDM separation means 203a separates the multiplexed signal (received signal) from the multiple blocks obtained by dividing each of the multiple subframes associated with the multiple layers in the time direction, which are distributed in the time direction within the frame.

[0086] Multiple layers may include a mobile reception layer and a fixed reception layer, and multiple subframes may include a mobile reception subframe #1 associated with the mobile reception layer and a fixed reception subframe #2 associated with the fixed reception layer. The TDM separation means 203a of the receiving device 200 that performs mobile reception may separate and acquire blocks belonging to mobile reception subframe #1 (mobile reception blocks). The TDM separation means 203a of the receiving device 200 that performs fixed reception may separate and acquire blocks belonging to fixed reception subframe #2 (fixed reception blocks).

[0087] The TDM separation means 203a of the receiving device 200 may separate the mobile receiving block and the fixed receiving block that are alternately arranged within the frame. Here, the mobile receiving block is a block obtained by dividing the mobile receiving subframe #1 in the time direction, and the fixed receiving block is a block obtained by dividing the fixed receiving subframe #2 in the time direction.

[0088] The TDM separation means 203a of the receiving device 200 may separate blocks obtained by dividing a plurality of subframes into symbol units, and each block is rearranged in the time direction within the frame using a predetermined randomization method. For example, the TDM separation means 203a of the receiving device 200 performs the reverse processing of the randomization process performed by the TDM means 103b of the transmitting device 100 to separate and acquire blocks belonging to a desired subframe.

[0089] The receiving means 201 of the receiving device 200 may receive control signals multiplexed with multiplexed signals, which are used for at least one of synchronization and control in broadcast transmission. The control signals may be preamble signals placed at the beginning of a frame, or TMCC signals following the preamble signals. The control signals include at least one of mode information indicating the mode to be applied from among intermittent reception on mode (first mode) and intermittent reception off mode (second mode), and division information indicating the number of divisions when dividing each of a plurality of subframes into blocks. The TDM separation means 203a of the receiving device 200 separates and acquires blocks belonging to a desired subframe based on the mode information and / or division information included in the control signals received by the receiving means 201.

[0090] (4) Example of a transmitting device An example of the transmitting device 100 according to this embodiment will be described with reference to Figure 13.

[0091] The transmitting device 100 includes a preamble signal generation unit 110 that generates a preamble signal, a TMCC signal generation unit 120 that generates a TMCC signal, a subframe #1 component 130a that constitutes subframe #1, a subframe #2 component 130b that constitutes subframe #2, an extension frame component 130c that constitutes an extension frame, a TDM frame component 140 that constitutes a frame, an orthogonal modulation unit 25, and a DAC (digital to analog converter) unit 26. The TDM frame component 140 constitutes at least a part of the TDM means 103b described above. The orthogonal modulation unit 25 and the DAC unit 26 constitute at least a part of the transmitting means 104 described above. Each of the parts shown in Figure 13 may operate in synchronization with the same sampling clock.

[0092] Figure 13 shows two subframe components, subframe #1 component 130a and subframe #2 component 130b, but three or more subframe components may be provided. Each subframe component has a similar block configuration. An example of providing a subframe component individually for each subframe is shown, but a configuration in which one subframe component is shared by time-division multiplexing is also possible. An example of using three layers, A to C, is shown, but a configuration using only two layers, A and B, is also possible. An example of providing two transmission systems, system 1 and system 2, is shown, but a configuration with only one system is also possible.

[0093] Subframe #1 component 130a includes energy spreading units 11 (11a, 11b, 11c) provided for each layer, error correction coding units 12 (12a, 12b, 12c) provided for each layer, carrier modulation units 13 (13a, 13b, 13c) provided for each layer, and system separation units 14 (14a, 14b, 14c) provided for each layer. When there is only one transmission system (for example, when using SISO), the system separation unit 14 is not required. The energy spreading units 11, error correction coding units 12, and carrier modulation units 13 constitute at least a part of the layered signal generation means 102 described above.

[0094] The energy diffusion unit 11 (11a, 11b, 11c) applies energy diffusion processing to the data of the corresponding hierarchical level and outputs the hierarchical data after energy diffusion processing. The error correction coding unit 12 (12a, 12b, 12c) applies error correction coding processing to the data of the corresponding hierarchical level and outputs the hierarchical data after error correction coding processing in FEC (Forward Error Correction) block units. LDPC (Low Density Parity Check) coding can be used as the error correction code. The carrier modulation unit 13 (13a, 13b, 13c) applies carrier modulation processing to the data of the corresponding hierarchical level, maps the data to a carrier, and outputs the hierarchical data (carrier symbol) after carrier modulation processing. Hereinafter, the hierarchical data after carrier modulation processing will be referred to as the hierarchical signal. The system separation unit 14 (14a, 14b, 14c) separates and outputs the hierarchical signals of the corresponding hierarchical levels into two systems.

[0095] Furthermore, the subframe #1 component 130a includes a hierarchical synthesis unit 15 (151, 152) provided for each system, a band division unit 16 (161, 162) provided for each system, a time interleave (IL) unit 17 (171, 172) provided for each system, a frequency IL unit 18 (181, 182) provided for each system, a band synthesis unit 19 (191, 192) provided for each system, a frame composition unit 20 (201, 202) provided for each system, an IFFT (Inverse Fast Fourier Transform) unit 21 (211, 212) provided for each system, a GI (Guard interval) addition unit 22 (221, 222) provided for each system, a MISO encoding unit 23, and a switching unit 24. The band splitting units 16 (161, 162) and the band combining units 19 (191, 192) constitute at least a part of the FDM means 103a described above.

[0096] The hierarchical synthesis unit 15 (151, 152) performs hierarchical synthesis processing on each hierarchical signal of the corresponding system and outputs each hierarchical signal after hierarchical synthesis processing. The band division unit 16 (161, 162) divides the hierarchically synthesized signal into each band by performing band division processing and outputs the hierarchical signal after band division processing. For example, a part of the C hierarchical signal is divided into an adjustment band as needed. The time IL unit 17 (171, 172) performs interleaving processing in the time direction (i.e., in the direction of the symbol arrangement order in each carrier) on the band-divided hierarchical signal and outputs the hierarchical signal after time interleaving. The frequency IL unit 18 (181, 182) performs interleaving processing in the frequency direction on the hierarchical signal after time interleaving and outputs the hierarchical signal after frequency interleaving. The band synthesis unit 19 (191, 192) synthesizes the signals of each band after frequency interleaving to constitute a data segment. The frame structuring unit 20 (201, 202) constructs an OFDM frame by adding a pilot signal (SP) and an Lch signal to the input carrier symbol (data segment). The IFFT unit 21 (211, 212) processes the OFDM frame using IFFT to generate a valid symbol signal. The GI addition unit 22 (221, 222) adds a GI signal, which is a copy of the end of the valid symbol signal, to the beginning of the valid symbol signal output by the IFFT unit 27. The GI is set so that the delay time of the multipath delay wave does not exceed the GI length. The frame structuring unit 20, the IFFT unit 21, and the GI addition unit 22 constitute the OFDM modulation unit. The MISO coding unit 23 performs spatiotemporal coding (STBC coding or SFBC coding) on ​​the 1-system signal to generate a 2-system signal. The switching unit 24 selects the output from the two-system bandwidth combining unit 192 in the case of spatial division multiplexing (SDM) using MIMO, and selects the output from the MISO encoding unit 23 in the case of MISO, and outputs it to the frame constructing unit 202. This switching is linked to the processing of the system separation unit 14.

[0097] The TDM frame configuration unit 140 (1401, 1402) multiplexes the preamble signal output by the preamble signal generation unit 110, the TMCC signal output by the TMCC signal generation unit 120, the subframe #1 signal output by the subframe #1 configuration unit 130a, the subframe #2 signal output by the subframe #2 configuration unit 130b, and the extension frame signal output by the extension frame configuration unit 130c into a single frame using TDM and outputs the multiplexed signal.

[0098] The quadrature modulation unit 25 (251, 252) quadrature modulates the signal output by the TDM frame constructor 140 (1401, 1402) and outputs it to the DAC unit 26. The DAC unit 26 (261, 262) performs digital-to-analog conversion on the quadrature modulated signal and outputs it as an IF signal. After predetermined modulation processing, the IF signal output is output from different antennas (transmission systems).

[0099] (5) Example of a receiving device An example of the receiving device 200 according to this embodiment will be described with reference to Figure 14.

[0100] The receiving device 200 includes a receiving unit 31, a preamble signal processing unit 32, a TMCC signal processing unit 33, a target subframe extraction unit 34, an FFT unit 35, a propagation path estimation unit 36, an equalization unit 37, a hierarchical separation unit 38, and a hierarchical signal processing means 204. The receiving unit 31 corresponds to the receiving means 201 described above. The preamble signal processing unit 32 and the TMCC signal processing unit 33 constitute the control signal processing means 202 described above. The target subframe extraction unit 34 constitutes the TDM separation means 203a described above. The hierarchical separation unit 38 constitutes the FDM separation means 203b described above.

[0101] The receiving unit 31 receives a signal in which the preamble signal, TMCC signal, and subframe signal are multiplexed using TDM, and outputs the received signal. The receiving unit 31 is composed of an ADC (analog to digital converter) unit and a quadrature demodulation unit, etc. The preamble signal processing unit 32 demodulates the preamble signal and acquires control information. Specifically, the preamble signal processing unit 32 identifies the amount of time shift applied to the preamble signal sequence in the time domain and acquires control information corresponding to the identified amount of shift. The TMCC signal processing unit 33 processes (demodulates and decodes) the TMCC signal based on the control information acquired by the preamble signal processing unit 32. The TMCC signal processing unit 33 acquires TMCC information with a variable number of bits depending on the number of subframes in the frame and the number of layers within each subframe. The target subframe extraction unit 34 extracts the subframe signal (OFDM signal) of the target subframe based on the TMCC information acquired by the TMCC signal processing unit 33. The FFT unit 35 performs an FFT on the OFDM signal from which the GI has been removed, converting it into a frequency-domain hierarchical signal. The propagation path estimation unit 36 ​​estimates the propagation path based on the arranged SPs and outputs the propagation path estimation result to the equalization unit 37. The equalization unit 37 uses the propagation path estimation result to perform an equalization process on the hierarchical signal and estimate the original carrier symbols. The hierarchical separation unit 38 separates the band-combined hierarchical signal into A-layer, B-layer, and C-layer carrier symbols based on the TMCC information acquired by the TMCC signal processing unit 33 and outputs them.

[0102] The hierarchical signal processing means 204 includes frequency deinterleaving (DIL) units 39 (39a, 39b, 39c) provided for each hierarchical level, time DIL units 40 (40a, 40b, 40c) provided for each hierarchical level, LLR calculation units 41 (41a, 41b, 41c) provided for each hierarchical level, error correction decoding units 42 (42a, 42b, 42c) provided for each hierarchical level, and energy despreading units 43 (43a, 43b, 43c) provided for each hierarchical level. The frequency DIL units 39 (39a, 39b, 39c) perform deinterleaving in the carrier frequency direction for the carrier symbols of the corresponding hierarchical level. The time DIL units 40 (40a, 40b, 40c) perform deinterleaving in the time direction for the frequency-deinterleaved carrier symbols, returning them to their original arrangement before interleaving on the transmitting side. The LLR calculation unit 41 (41a, 41b, 41c) calculates the LLR (Log Likelihood Ratio) of the carrier symbols of the corresponding hierarchical level. The error correction decoding unit 42 (42a, 42b, 42c) performs error correction decoding based on the LLR. The energy despreading unit 43 (43a, 43b, 43c) applies energy despreading to the hierarchical signal after error correction decoding and outputs it.

[0103] (6) Effects of the Embodiment The effects of this embodiment will be explained based on computer simulation results with reference to Figures 15 and 16.

[0104] As shown in Figure 15(a), the comparative example is an example of intermittent reception on mode, i.e., no block division of each subframe is performed. Here, it is assumed that mobile reception subframe #1 is 10 symbols (14 μs), fixed reception subframe #2 is 54 symbols (287 μs), and the total data area within each subframe is 301 μs.

[0105] On the other hand, as shown in Figure 15(b), the embodiment is an example of intermittent reception off mode, that is, an example in which each subframe is divided into blocks. Here, the number of divisions is assumed to be "10". Note that the parameters such as the FFT size applied to each subframe are the same in the comparative example and the embodiment.

[0106] As shown in Figure 16, a comparison of the required C / N with respect to the maximum Doppler frequency shows that the embodiment has an improved required C / N compared to the comparative example. Here, the mobile receiver signal placed in mobile receiver subframe #1 has an FFT size of 8kFFT, a modulation scheme of QPSK, a coding rate of 7 / 16, and a time interleave parameter I=1.

[0107] Thus, the TDM means 103b of the transmitting device 100 according to this embodiment divides each of the multiple subframes associated with multiple layers into multiple blocks in the time direction, and arranges these multiple blocks in a time-distributed manner within the frame. This makes it possible to mitigate the effects of degradation of some signals within a frame due to a decrease in reception level. Therefore, it is possible to improve the time interleaving effect in TDM without increasing the interleaving length (without increasing the transmission delay).

[0108] (7) Other embodiments The preamble signal mentioned above can be any signal placed at the beginning of a frame or a signal used for synchronization, and signals with similar configuration and function are included in the term "preamble signal." Therefore, it may be called by other names such as "synchronization signal." Similarly, the TMCC signal mentioned above can be any signal used for control (various settings) in broadcast transmission, and signals with similar configuration and function are included in the term "TMCC signal." Therefore, it may be called by other names such as "control signal" or "setting signal."

[0109] A program may be provided that causes a computer to execute each of the processes performed by the above-described devices (transmitter 100, receiver 200). The program may be recorded on a computer-readable medium. Using a computer-readable medium, it is possible to install the program on a computer. Here, the computer-readable medium on which the program is recorded may be a non-transient recording medium. The non-transient recording medium is not particularly limited, but may be a recording medium such as a CD-ROM or DVD-ROM. Furthermore, the circuits that execute each of the processes performed by the above-described devices (transmitter 100, receiver 200) may be integrated, and the device may be configured using a semiconductor integrated circuit (chipset, SoC).

[0110] Although the embodiments have been described in detail above with reference to the drawings, the specific configuration is not limited to those described above, and various design changes can be made without departing from the gist of the invention. [Explanation of Symbols]

[0111] 1: Broadcasting System 11: Energy diffusion section 12: Error Correction Encoding Unit 13: Carrier modulation section 14: System separation section 15: Hierarchical Composition Unit 16: Bandwidth division section 17: Time IL section 18: Frequency IL section 19: Bandwidth Synthesis Unit 20: Frame component 21:IFFT section 22: GI addition section 23:MISO encoder 24: Switching section 25: Quadrature Modulation Section 26:DAC section 27:IFFT section 31: Receiving unit 32: Preamble signal processing unit 33: TMCC signal processing unit 34: Target subframe extraction section 35:FFT section 36: Propagation path estimation unit 37: Equalization section 38: Hierarchical separation section 39: Frequency DIL section 40: Time DIL Department 41: LLR calculation unit 42: Error correction and decoding unit 43: Energy backdiffusion section 100: Transmitter 101: Control signal generation means 102: Hierarchical signal generation means 103: Multiple means 103a :FDM means 103b :TDM means 104: Transmission method 110: Preamble signal generation unit 111:Sequence generator 112: Mapping section 113: Conversion section 114: Control Information Generation Unit 115: Relative cyclic shift section 116: Absolute Cyclic Shift Section 117: Cyclic shift section 118: CP addition part 120:TMCC signal generation section 120a:TMCC information generation section 121: Energy diffusion section 122: Error Correction Encoding Unit 123: Repetitive coding section 124: Carrier modulation section 125: Phase rotation section 126: Frequency IL section 127: Pilot insertion section 128:IFFT section 129: GI addition 130a: Subframe A component 130b: Subframe B component 130c: Expansion frame component 140: TDM frame components 200: Receiving device 201: Receiving means 202: Control signal processing means 203: Demultiplexing means 203a :TDM separation means 203b :FDM separation means 204: Hierarchical signal processing means

Claims

1. A transmitting device used in a broadcasting system that performs hierarchical transmission, A time-division multiplexing means that multiplexes signals of multiple layers within a frame using time-division multiplexing, The system includes a transmitting means for transmitting multiplexed signals multiplexed by the time-division multiplexing means, The time-division multiplexing means is characterized by dividing each of the multiple subframes associated with the multiple layers, each of which can be set to have a different FFT (Fast Fourier Transform) size and a different GI (Guard Interval) length, into a plurality of blocks in the time direction, and distributing the plurality of blocks in the time direction within the frame.

2. The aforementioned multiple layers include a mobile receiving layer and a fixed receiving layer, The transmitting device according to claim 1, characterized in that the plurality of subframes include a mobile receiving subframe associated with the mobile receiving layer and a fixed receiving subframe associated with the fixed receiving layer.

3. The transmission device according to claim 2, characterized in that the time-division multiplexing means divides the mobile receiving subframe into mobile receiving blocks and the fixed receiving subframe into fixed receiving blocks, and alternately arranges the mobile receiving blocks and the fixed receiving blocks within the frame.

4. A transmitting device for use in a broadcasting system that performs hierarchical transmission, A time-division multiplexing means for multiplexing signals of multiple layers within a frame by time-division multiplexing, wherein each of the multiple subframes associated with the multiple layers is divided into multiple blocks in the time direction, and the multiple blocks are distributed and arranged in the time direction within the frame; The system includes a transmitting means for transmitting multiplexed signals multiplexed by the time-division multiplexing means, The time-division multiplexing means is a transmitting device characterized by dividing the plurality of subframes into blocks on a symbol-by-symbol basis and arranging each block, which has been rearranged in the time direction using a predetermined randomization method, within the frame.

5. The transmission device according to any one of claims 1 to 4, characterized in that the time-division multiplexing means switches between a first mode in which the plurality of subframes are arranged within the frame without block division, and a second mode in which the plurality of blocks obtained by block division are arranged in a time-distributed manner within the frame.

6. The first mode is a mode in which the plurality of subframes are arranged in a continuous manner in the time direction within the frame in order to enable intermittent reception in which the receiving side selectively receives only a specific subframe, The transmitting device according to claim 5, characterized in that the second mode is a mode that restricts intermittent reception on the receiving side by distributing the plurality of blocks obtained by dividing each of the plurality of subframes alternately in the time direction.

7. A receiving device used in a broadcasting system that performs hierarchical transmission, A receiving means for receiving a multiplexed signal obtained by multiplexing multiplexed signals of multiple layers within a frame using time division multiplexing from a transmitting device, The system comprises a plurality of blocks obtained by dividing each of the plurality of subframes associated with the plurality of layers in the time direction, and a time-division multiplexing means for separating the plurality of blocks, which are distributed in the time direction within the frame, from the multiplexed signal. The receiving device is characterized in that the plurality of subframes can be set to have at least one of different FFT (Fast Fourier Transform) sizes and different GI (Guard Interval) lengths.

8. The aforementioned multiple layers include a mobile receiving layer and a fixed receiving layer, The receiving device according to claim 7, characterized in that the plurality of subframes include a mobile receiving subframe associated with the mobile receiving layer and a fixed receiving subframe associated with the fixed receiving layer.

9. The time-division multiplexing means separates the mobile receiving blocks and fixed receiving blocks that are alternately arranged within the frame. The aforementioned mobile receiving block is a block obtained by dividing the mobile receiving subframe in the time direction, The receiving device according to claim 8, characterized in that the fixed receiving block is a block obtained by dividing the fixed receiving subframe in the time direction.

10. A receiving device for use in a broadcasting system that performs hierarchical transmission, A receiving means for receiving a multiplexed signal obtained by multiplexing multiplexed signals of multiple layers within a frame using time division multiplexing from a transmitting device, The system comprises a plurality of blocks obtained by dividing each of the plurality of subframes associated with the plurality of layers in the time direction, and a time-division multiplexing means for separating the plurality of blocks, which are distributed in the time direction within the frame, from the multiplexed signal. The time-division multiplexing means is a receiving device characterized by separating each block obtained by dividing the plurality of subframes into symbol units, and sorting each block in the time direction within the frame using a predetermined randomization method.

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