Transmitter and receiver

Abstract

To increase transmission capacity by reducing a ratio of SPs to all signals in a broadcasting system using TDM.SOLUTION: A transmitter used in a broadcasting system that performs layered transmission includes: SP arrangement means for arranging SPs (Scattered Pilots) within a frame; time division multiplexing means for multiplexing signals of a plurality of layers within the frame by time division multiplexing; and transmission means for transmitting the multiplexed signals multiplexed by the time division multiplexing means. The SP arrangement means arranges the SPs only in specific sub-frames among a plurality of sub-frames associated with the plurality of layers.SELECTED DRAWING: Figure 15

Description

Technical Field

[0001] The present invention relates to a transmission device and a reception device used in a broadcast system.

Background Art

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

[0003] In ISDB-T, mobile reception services and fixed reception services are simultaneously provided in one channel by hierarchical transmission. In the advanced terrestrial broadcasting method, it is also assumed that a plurality of services and contents are transmitted within one channel by hierarchical transmission.

[0004] Here, in ISDB-T, hierarchical transmission based on frequency division multiplexing (FDM) is possible. Specifically, the transmission band of one channel is divided into 13 segments, and segments are respectively allocated for mobile reception and fixed reception, thereby realizing hierarchical transmission. By setting the mobile reception layer in the central one segment, narrow-band reception can be performed, which is advantageous in that power-saving reception can be achieved for the reception device.

[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.

[0007] 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. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2018-198426 [Non-patent literature]

[0009] [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] ATSC3.0 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 project] [Problems that the invention aims to solve]

[0010] When using TDM as a multiplexing method in a broadcasting system, the temporal interleaving effect in TDM can be improved without increasing transmission delay by dividing each of the multiple subframes into multiple blocks in the temporal direction and distributing these multiple blocks within the frame in the temporal direction.

[0011] However, distributing the signals across multiple locations results in multiple subframe boundaries (block boundaries) within a single frame. This can lead to complexity in transmission path estimation, as signals with different SP (Scattered Pilot) configurations may switch at the block level. While frame boundary SPs can be inserted at subframe boundaries (block boundaries) to reduce complexity, inserting multiple frame boundary SPs reduces transmission capacity.

[0012] Therefore, the present invention aims to provide a transmitting device and a receiving device that can increase transmission capacity in a broadcasting system using TDM by reducing the ratio of SP to the total signal. [Means for solving the problem]

[0013] The first embodiment of the transmitting device is a transmitting device used in a broadcasting system that performs hierarchical transmission, and comprises SP placement means for placing SPs (Scattered Pilots) within a frame, time division multiplexing means for multiplexing signals of multiple layers within the frame by time division multiplexing, and transmitting means for transmitting the multiplexed signals multiplexed by the time division multiplexing means. The SP placement means places the SPs only in specific subframes among a plurality of subframes associated with the plurality of layers.

[0014] The receiving device according to the second embodiment is a receiving device used in a broadcasting system that performs hierarchical transmission, and comprises: receiving means for transmitting a multiplexed signal obtained by multiplexing signals of multiple layers within a frame by time division multiplexing from a transmitting device; time division multiplexing separation means for separating a first subframe in which an SP (Scattered Pilot) is placed and a second subframe in which no SP is placed from the multiplexed signal among a plurality of subframes associated with the plurality of layers; and transmission path estimation means for performing transmission path estimation for the second subframe using the SP placed in the first subframe. [Effects of the Invention]

[0015] According to the present invention, in a broadcasting system using TDM, it is possible to provide a transmitting device and a receiving device that can increase the transmission capacity by reducing the ratio of SP to the total signal. [Brief explanation of the drawing]

[0016] [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]FIG. is a diagram showing a signal configuration example when TDM arrangement and FDM arrangement are used for the signal configuration of a hierarchical signal. [Figure 5] FIG. is a diagram showing a signal configuration example when a combination of FDM and TDM is used for the signal configuration of a hierarchical signal. [Figure 6] FIG. is a diagram showing a signal configuration example when a frame boundary pilot is used. [Figure 7] FIG. is a diagram showing the operation in the intermittent reception on-mode according to an embodiment. [Figure 8] FIG. is a diagram showing the operation in the intermittent reception off-mode according to an embodiment. [Figure 9] FIG. is a diagram showing the operation in the intermittent reception off-mode according to an embodiment. [Figure 10] FIG. is a diagram showing the operation in the intermittent reception off-mode according to an embodiment. [Figure 11] FIG. is a diagram showing the operation in the intermittent reception off-mode according to an embodiment. [Figure 12] FIG. is a diagram showing the operation in the intermittent reception off-mode according to an embodiment. [Figure 13] FIG. is a diagram for explaining the SP arrangement and transmission path estimation in the intermittent reception off-mode according to an embodiment. [Figure 14] FIG. is a diagram for explaining the SP arrangement and transmission path estimation in the intermittent reception off-mode according to an embodiment. [Figure 15] FIG. is a diagram for explaining the SP arrangement and transmission path estimation in the intermittent reception off-mode according to an embodiment. [Figure 16] FIG. is a diagram for explaining the SP arrangement and transmission path estimation in the intermittent reception off-mode according to an embodiment. [Figure 17] FIG. is a diagram for explaining the SP arrangement and transmission path estimation in the intermittent reception off-mode according to an embodiment. [Figure 18] An example of a transmission device according to an embodiment will be described. [Figure 19] An example of a reception device according to an embodiment will be described. [Figure 20]This figure shows Example 1 and its comparative example (Comparative Example 1). [Figure 21] This figure compares the required C / N ratio for Example 1 and Comparative Example 1 with respect to the maximum Doppler frequency. [Figure 22] This figure shows Example 2 and its comparative example (Comparative Example 2). [Figure 23] This figure compares the reception characteristics of Subframe #2 in a fixed reception environment (AWGN multipath) between Example 2 and Comparative Example 2. [Modes for carrying out the invention]

[0017] Embodiments will be described with reference to the drawings. In the following drawings, identical or similar parts are denoted by the same or similar reference numerals.

[0018] (1) Broadcasting system First, the broadcasting system according to this embodiment will be described with reference to Figures 1 to 3. The broadcasting system according to this embodiment is a system that corresponds to the advanced terrestrial broadcasting system and is a terrestrial digital television broadcasting system that performs hierarchical transmission.

[0019] (1.1) Transmission bandwidth in broadcasting systems Referring to Figure 1, the transmission bandwidth in the broadcasting system according to this embodiment will be described. In this embodiment, the total bandwidth of one channel is assumed to be 6 MHz.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] (1.2) Overview of the multiplexing method Refer to Figure 2 to explain the characteristics of TDM and FDM.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] (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.

[0034] (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, an SP (Scattered Pilot) placement means 104, and a transmitting means 105.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] The SP placement means 104 places SPs within a frame. SPs are pilot signals (i.e., known signals) that are distributed in the time-frequency direction and are used by the receiving device 200 to perform transmission path estimation. In this embodiment, the SP placement means 104 places SPs only in a specific subframe (also called the "first subframe") among a plurality of subframes associated with a plurality of layers. Details of this operation will be described later.

[0047] The transmitting means 105 transmits the multiplexed signal, which has been multiplexed by the multiplexing means 103, via broadcast waves. The transmitting means 105 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 105 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.

[0048] (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, a transmission path estimation means 204, an equalization means 205, and a hierarchical signal processing means 206.

[0049] 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.

[0050] 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.

[0051] The multiplexing / decoupling means 203 multiplexes and decouples multiple layers of signals from a received signal (multiplexed signal) based on 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 (i.e., a desired 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.

[0052] In this embodiment, the TDM separation means 203a separates a first subframe in which an SP is located and a second subframe in which no SP is located from the multiplexed signals, among a plurality of subframes associated with a plurality of layers. The transmission path estimation means 204 performs transmission path estimation to estimate the transmission path characteristics using the SP located in the first subframe. For example, the transmission path estimation means 204 performs transmission path estimation for the first subframe using the SP located in the first subframe. The transmission path estimation means 204 also performs transmission path estimation for the second subframe using the SP located in the first subframe. The equalization means 205 performs equalization processing on the layer signals of each subframe using the transmission path estimation results from the transmission path estimation means 204. Details of the operation related to transmission path estimation will be described later.

[0053] The hierarchical signal processing means 206 processes (demodulates and decodes) the hierarchical signal output by the multiplexing 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.

[0054] (2) Example of signal configuration An example of a signal configuration according to this embodiment will be described with reference to Figures 4 to 6.

[0055] (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.

[0056] 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.

[0057] 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.

[0058] 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).

[0059] 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.

[0060] 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.

[0061] 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.

[0062] (2.2) Example of SP arrangement Figure 6 shows an example of SP (Scattered Pilot) placement. In Figure 6, an example is shown in which not only normal SPs but also frame boundary SPs (Scattered Pilots) are placed, but in this embodiment, frame boundary SPs do not need to be placed.

[0063] Frame boundary SPs may have a higher pilot density than normal SPs. When a signal is composed of multiple subframes, transmission path estimation at subframe boundaries can become complex; therefore, inserting frame boundary SPs can improve the accuracy of transmission path estimation at 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. SP parameters 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 data carriers between symbols can be kept constant.

[0064] 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".

[0065] (3) Operation in TDM The operation of TDM according to this embodiment will be described with reference to Figures 7 to 12.

[0066] (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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] (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.

[0074] (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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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).

[0079] 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.

[0080] In intermittent reception off mode, multiple boundaries between subframe #1 and subframe #2 are generated. The SP arrangement 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. However, in this embodiment, frame boundary SPs may be turned off.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] (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.

[0090] 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).

[0091] 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.

[0092] 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.

[0093] 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.

[0094] (3.2.3) SP placement and transmission path estimation in intermittent reception off mode This embodiment describes the SP arrangement and transmission path estimation in the intermittent reception off mode.

[0095] The transmitting device 100 includes an SP placement means 104 for placing SPs within a frame, a TDM means 103b for multiplexing signals of multiple layers within a frame by time division multiplexing, and a transmitting means 105 for transmitting the multiplexed signals by the TDM means 103b. In intermittent reception off mode, the SP placement means 104 places SPs only in a specific subframe (the first subframe) among the multiple subframes associated with the multiple layers. That is, in intermittent reception off mode, the SP placement means 104 does not place SPs in subframes other than the specific subframe. This makes it possible to reduce the proportion of SPs compared to when SPs are placed in all subframes, and to increase the transmission capacity. In intermittent reception on mode, the SP placement means 104 may place SPs in all subframes.

[0096] In intermittent reception off mode, the receiving device 200 includes a receiving means 201 that transmits a multiplexed signal obtained by multiplexing signals of multiple layers within a frame using time-division multiplexing from the transmitting device 100; a TDM separation means 203a that separates a first subframe in which an SP is located and a second subframe in which no SP is located from the multiplexed signal, among a plurality of subframes associated with the plurality of layers; and a transmission path estimation means 204 that performs transmission path estimation for the second subframe using the SP located in the first subframe. In this way, since transmission path estimation for the second subframe is performed using the SP located in the first subframe, it becomes possible to perform transmission path estimation for the second subframe even if no SP is located in the second subframe.

[0097] The SP placement means 104 of the transmitting device 100 places SPs only in a specific subframe (the first subframe) among multiple subframes in the intermittent reception off mode. Specifically, in the intermittent reception off mode, the TDM means 103b of the transmitting device 100 divides each of the multiple subframes into multiple blocks in the time direction and places these multiple blocks distributed in the time direction within the frame. The SP placement means 104 of the transmitting device 100 places SPs in the blocks belonging to the specific subframe.

[0098] On the other hand, the TDM separation means 203a of the receiving device 200 separates from the multiplexed signals multiple blocks obtained by dividing each of the multiple subframes in the time direction, and which are distributed in the time direction within the frame. The transmission path estimation means 204 of the receiving device 200 performs transmission path estimation for blocks belonging to the second subframe using SPs placed in the blocks belonging to the first subframe. Specifically, for subframe #1, the transmission path estimation means 204 of the receiving device 200 performs transmission path estimation using SPs within subframe #1, but for subframe #2, it performs transmission path estimation using SPs in each block of subframe #1 before and after the block of subframe #2.

[0099] Thus, in intermittent reception off mode, each subframe is divided into multiple blocks and arranged in a time-distributed manner within the frame. Therefore, even if SPs are placed only in a specific subframe (the first subframe), the SPs will be distributed in a time-distributed manner within the frame. Consequently, the transmission path estimation means 204 of the receiving device 200 can accurately estimate the transmission path for blocks belonging to the second subframe using SPs placed in blocks belonging to the first subframe.

[0100] Multiple subframes arranged within a frame 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 SP placement means 104 of the transmitting device 100 may place SPs in the mobile reception subframe #1, which is a specific subframe (first subframe). That is, in the intermittent reception off mode, the SP placement means 104 of the transmitting device 100 may place SPs in the mobile reception subframe #1 without placing SPs in the fixed reception subframe #2. Since the mobile reception subframe #1 is used for mobile reception services, the transmission path fluctuations are more severe compared to fixed reception services. Therefore, placing SPs in the mobile reception subframe #1 makes it easier to follow the transmission path fluctuations. In contrast, since the fixed reception subframe #2 is used for fixed reception services, there is a high need for high-quality and high-capacity transmission. Therefore, by not placing SPs in the fixed reception subframe #2, it becomes possible to increase the transmission capacity of the fixed reception service.

[0101] The control signal generation means 101 of the transmitting device 100 may generate a control signal (preamble signal or TMCC signal) that includes SP information indicating the presence or absence of SPs for each of the multiple subframes within the frame. For example, the TMCC signal generation unit 120 of the control signal generation means 101 may generate a TMCC signal that includes a flag indicating the presence or absence of SPs in subframe #1 and a flag indicating the presence or absence of SPs in subframe #2. Alternatively, the TMCC signal generation unit 120 may set a value indicating the absence of SPs in the information specifying the SP placement for each subframe. For example, the TMCC signal generation unit 120 may set values ​​indicating the Dx and Dy of SPs as the SP placement for subframe #1 and set a value indicating the absence of SPs as the SP placement for subframe #2. The receiving means 201 of the receiving device 200 receives the control signal multiplexed into the multiplexed signal. The transmission path estimation means 204 of the receiving device 200 determines which subframes have SPs based on the SP information included in the control signal.

[0102] The TDM means 103b of the transmitting device 100 may place blocks belonging to a specific subframe (e.g., mobile reception subframe #1) at at least one of the beginning and end of the data area within the frame. This ensures that SPs are placed at at least one of the beginning and end of the data area, enabling the transmission path estimation means 204 of the receiving device 200 to perform transmission path estimation smoothly. For example, as shown in Figures 13 and 14, the TDM means 103b places blocks (symbols) belonging to mobile reception subframe #1 at the beginning and end of the data area within the frame. The control signal generation means 101 of the transmitting device 100 may notify information indicating whether the last symbol of the frame is subframe #1 by a control signal (e.g., TMCC signal).

[0103] Figure 13 shows an example where mobile reception subframe #1 is divided into five blocks, each containing one symbol. Also in Figure 13, an example where fixed reception subframe #2 is divided into four blocks, each containing two symbols. Figure 14 shows another example where mobile reception subframe #1 is divided into five blocks, each containing one symbol. Also in Figure 14, an example where fixed reception subframe #2 is divided into four blocks, with two of these blocks containing two symbols and the remaining two blocks containing three symbols. Figure 14 shows how to calculate the number of fixed reception symbols (m, m+1) between mobile reception symbols.

[0104] In Figures 13 and 14, examples are shown in which the symbols at the beginning and end of the data area within a frame are arranged to be the signals of subframe #1. However, the symbols at the beginning and end of the data area within a frame do not necessarily have to be the signals of subframe #1. For example, the transmission path estimation means 204 of the receiving device 200 may use the preamble signal transmitted at the beginning of each frame to estimate the transmission path at the end of the frame immediately preceding the current frame. Alternatively, the transmission path estimation means 204 can use the preamble signal, as it contains all known symbols. Thus, the transmission path estimation means 204 may use the preamble signal placed at the beginning of the frame to estimate the transmission path for at least one of the beginning and end of the frame.

[0105] Figure 15 shows a specific example of SP arrangement according to this embodiment. In Figure 15, an example is shown in which mobile reception subframe #1 is divided into 10 blocks, with each block representing one symbol. Another example is shown in which fixed reception subframe #2 is divided into 9 blocks, with each block representing one symbol. The SP arrangement means 104 of the transmitting device 100 arranges SPs in each block (each symbol) of mobile reception subframe #1. The SPs are arranged on carriers at the same position in the frequency direction.

[0106] Regarding the time interval (Dy) of SP placement, generally, a small Dy is used for mobile reception where the time variation of the transmission path is large, and a large Dy is used for fixed reception where the time variation of the transmission path is small. In the example in Figure 15, Dy=1 is used for mobile reception subframe #1, and the transmission path estimation means 204 of the receiving device 200 can perform transmission path estimation for each symbol. Although fixed reception subframe #2 does not contain SPs, the transmission path estimation means 204 can estimate the transmission path characteristics of fixed reception subframe #2 by interpolating in the time direction from the SPs of the preceding and succeeding subframes #1. For example, when the transmission path estimation means 204 estimates the transmission path characteristics of a carrier symbol within a block of fixed reception subframe #2, it first estimates the transmission path characteristics using the SPs in the blocks of mobile reception subframe #1 before and after the carrier symbol, and then estimates the transmission path characteristics of the carrier symbol as the average of the transmission path characteristics of the preceding and succeeding SPs.

[0107] In the example shown in Figure 15, blocks of subframe #1 and subframe #2 are arranged alternately with one symbol each. However, even when there are many fixed reception symbols (subframe #2) and two or more subframe #2 blocks are arranged consecutively, interpolation in the time direction can be performed using the SPs of the preceding and succeeding subframe #1 blocks. Such interpolation does not cause significant degradation in fixed reception with little time variation. In this embodiment, since subframe #2 does not contain SPs, data (hierarchical signals) can be placed in place of SPs, thereby increasing transmission capacity. For example, compared to cases where (Dx=24,Dy=1) or (Dx=24,Dy=2) are used as the SP arrangement for subframe #2, this embodiment can increase transmission capacity by 4.2% (1 / 24) and 2.1% (1 / 48), respectively.

[0108] Figure 16 shows a specific example 2 of the SP arrangement according to this embodiment. Specific example 2 is an SP arrangement in which the SPs in the frequency direction are denser compared to specific example 1.

[0109] The detectionable multipath delay time length changes depending on the frequency-direction SP spacing (Dx). Therefore, the value of Dx is usually set to allow detection of values ​​longer than the guard interval length. For this reason, if the guard interval lengths set for subframe #1 and subframe #2 are different, Dx must be set individually. In the example in Figure 15, the delay wave that subframe #2 can detect is the same as that of subframe #1, so it is not suitable for cases where different guard interval lengths are set between subframes as described above. Therefore, Figure 16 shows a configuration in which the SP ratio of subframe #1 is the same as in Figure 15, but subframe #2 can detect longer delay waves. Specifically, the SP placement means 104 of the transmitter 100 places SPs shifted in the frequency direction between two blocks of subframe #1 that are continuous in the time direction. Here, by using (Dx=3, Dy=2) as the SP placement for subframe #1, the number of SPs with frequency-direction spacing that can be interpolated in subframe #2 is increased. Furthermore, in subframe #1, the arrangement is (Dx=6, Dy=1) when viewed on a symbol-by-symbol basis, so the same characteristics as the configuration in Figure 15 are obtained.

[0110] Figure 17 shows a specific example 3 of the SP arrangement according to this embodiment. The difference from Figure 16 is that the symbols of subframe #1 are arranged in units of Dy (here, Dy=2). In Figure 17, an example is shown in which mobile reception subframe #1 is divided into 5 blocks, with each block containing 2 symbols. Another example is shown in which fixed reception subframe #2 is divided into 4 blocks, with each block containing 2 symbols. As described above, the number of divisions is set when intermittent reception is off mode, and the settings shown in Figures 16 and 17 become possible depending on the number of divisions set.

[0111] In this embodiment, the power allocated to the data carriers differs between subframe #1 and subframe #2 depending on the presence or absence of SPs. Therefore, the transmission path estimation means 204 may perform transmission path estimation to correct for the power level difference (difference in data power) between the data carriers of subframe #1 and subframe #2. For example, since SPs are inserted with boosting, the transmission path estimation means 204 may perform transmission path estimation after adjusting the power level of the SPs to match the data. Also, since the FFT sizes differ between subframe #1 and subframe #2, the transmission path estimation means 204 may interpolate the transmission path estimation value corrected to the number of carriers in subframe #2 by oversampling.

[0112] (4) Example of a transmitting device An example of the transmitting device 100 according to this embodiment will be described with reference to Figure 18.

[0113] 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 105 described above. Each of the parts shown in Figure 18 may operate in synchronization with the same sampling clock.

[0114] Figure 18 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.

[0115] 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.

[0116] 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.

[0117] 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 section 16 (161, 162) and the band combining section 19 (191, 192) constitute at least a part of the FDM means 103a described above. The frame configuration section 20 (201, 202) constitutes at least a part of the SP placement means 104 described above.

[0118] 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 SP and Lch signals 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.

[0119] 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.

[0120] 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).

[0121] (5) Example of a receiving device Referring to Figure 19, an example of the receiving device 200 according to this embodiment will be described. Here, an example of the configuration of the receiving device 200 in intermittent reception off mode will be described.

[0122] 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, and an FFT (Fast Fourier Transform) provided for each subframe. The receiver unit 31 has a Transform unit 35 (35#1, 35#2), a transmission path estimation unit 36 ​​(36#1, 36#2) provided for each subframe, an equalization unit 37 (37#1, 37#2) provided for each subframe, a hierarchical separation unit 38 (38#1, 38#2) provided for each subframe, a frequency deinterleaving (DIL) unit 39 (39#1, 39#2) provided for each subframe, a time DIL unit 40 (40#1, 40#2) provided for each subframe, an LLR calculation unit 41 (41#1, 41#2) provided for each subframe, an error correction decoding unit 42 (42#1, 42#2) provided for each subframe, and an energy despreading unit 43 (43#1, 43#2) provided for each subframe. The receiver 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 (38#1, 38#2) constitutes the FDM separation means 203b described above. The transmission path estimation unit 36 ​​(36#1, 36#2) constitutes the transmission path estimation means 204 described above. The equalization unit 37 (37#1, 37#2) constitutes the equalization means 205 described above.

[0123] The receiving unit 31 receives a signal in which the preamble signal, TMCC signal, and subframe signal are multiplexed by 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 time-domain preamble signal sequence and acquires control information corresponding to the identified shift amount. 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.

[0124] 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 target subframe extraction unit 34 may also extract the subframe signal in block units. The target subframe extraction unit 34 outputs the subframe #1 signal to the FFT unit 35#1 and the subframe #2 signal to the FFT unit 35#2. The FFT units 35 (35#1, 35#2) perform FFT processing on the OFDM signal from which the GI has been removed, converting it into a hierarchical signal in the frequency domain.

[0125] The transmission path estimation unit 36 ​​(36#1, 36#2) performs transmission path estimation using the SPs that are placed in the subframe and outputs the transmission path estimation result to the equalization unit 37. Specifically, the transmission path estimation unit 36#1 estimates the transmission path characteristics of subframe #1 using the SPs placed in subframe #1 and outputs the estimated transmission path characteristics to the equalization unit 37#1.

[0126] The transmission path estimation unit 36#2 estimates the transmission path characteristics of subframe #2 using SPs placed in subframe #1 and outputs the estimated transmission path characteristics to the equalization unit 37#2. The transmission path estimation unit 36#2 includes an SP extraction unit 361, a level correction unit 362, and a transmission path estimation value interpolation unit 363. The SP extraction unit 361 extracts SPs placed in subframe #1. The level correction unit 362 corrects the amplitude of the SPs to correct the power level difference between the data carriers of subframe #1 and subframe #2. The transmission path estimation value interpolation unit 363 estimates the transmission path characteristics of subframe #1 using the SPs, interpolates the transmission path characteristics of subframe #2 from the estimated transmission path characteristics, and outputs the transmission path characteristics of subframe #2 to the equalization unit 37#2.

[0127] Here, we will explain the details of the level correction unit 362. Subframe #1 contains a power-boosted SP, but subframe #2 does not contain an SP. Since the total transmission power is constant, the power allocated to the data carrier is greater in subframe #2 than in subframe #1. Therefore, the level correction unit 362 performs a correction to use the estimated transmission path value (transmission path characteristics) estimated (calculated) for subframe #1 in subframe #2.

[0128] For example, consider subframe #1 with an FFT size of 8kFFT, 216 carriers in one segment (36 SPs and 180 datas), and an SP boost ratio of 1.5. In this case, the transmitting side normalizes the signal so that the total power is 1. The signal power of subframe #1 before normalization is calculated by multiplying the number of carriers by the boost ratio. 36 × 1.5 × 1.5 + 180 × 1 × 1 = 261 This is how it is obtained. And for normalization, the total number of carriers / power before normalization is 216 / 261 = 0.827... This value is calculated and then multiplied by all carriers to perform the correction. However, in practice, the correction is performed using the amplitude value, so the value obtained by taking the square root of the above value is used.

[0129] In contrast, subframe #2, which does not contain SP, does not require normalization, so its total power is assumed to be 1. Therefore, the transmission path estimate obtained in subframe #1 corresponds to a value reduced to 0.827... times the above for subframe #2. Accordingly, the level correction unit 362 corrects the transmission path estimate of subframe #1 by dividing it by 0.827... and uses this correction for subframe #2. However, in practice, the amplitude value is used for correction, so the square root of the above value is used.

[0130] The equalization unit 37 (37#1, 37#2) performs equalization processing on the subframe signal (hierarchical signal) using the transmission path estimation result to estimate the original carrier symbol. The hierarchical separation unit 38 (38#1, 38#2) separates the bandwidth-combined subframe signal (hierarchical signal) into hierarchical units for each carrier symbol and outputs it based on the TMCC information acquired by the TMCC signal processing unit 33.

[0131] The frequency DIL section 39 (39#1, 39#2) performs deinterleaving in the carrier frequency direction for the carrier symbols of the corresponding hierarchical level. The time DIL section 40 (40#1, 40#2) performs 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 section 41 (41#1, 41#2) calculates the LLR (Log Likelihood Ratio) of the carrier symbols of the corresponding hierarchical level. The error correction decoding section 42 (42#1, 42#2) performs error correction decoding based on the LLR. The energy despreading section 43 (43#1, 43#2) applies energy despreading to the hierarchical signal after error correction decoding and outputs it.

[0132] (6) Effects of the Embodiment The effects of this embodiment will be explained based on computer simulation results with reference to Figures 20 to 23.

[0133] Figure 20 shows Example 1 and its comparative example (Comparative Example 1). As shown in Figure 20(a), Comparative Example 1 is an example of intermittent reception on mode, that is, an example in which block division of each subframe is not 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. On the other hand, as shown in Figure 20(b), Example 1 is an example of intermittent reception off mode, that is, an example in which block division of each subframe is performed. Here, it is assumed that the number of divisions is "10". The parameters such as the FFT size applied to each subframe are the same in Comparative Example 1 and Example 1.

[0134] As shown in Figure 21, when comparing the required C / N with respect to the maximum Doppler frequency, Example 1 shows an improved required C / N compared to Comparative Example 1. 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.

[0135] 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).

[0136] Figure 22 shows Example 2 and a comparative example thereof (Comparative Example 2). As shown in Figure 22(a), Comparative Example 2 is an example of intermittent reception on mode, that is, an example in which block division of each subframe is not performed. Here, mobile reception subframe #1 is 45 symbols (64 μs), fixed reception subframe #2 is 44 symbols (233 μs), and the total data area within each subframe is 297 μs. SPs are placed in both mobile reception subframe #1 and fixed reception subframe #2, and mobile reception subframe #1 has an SP configuration (Dx, Dy) of SP(6,1) and an SP boost ratio of 1.29, while fixed reception subframe #2 has an SP configuration (Dx, Dy) of SP(24,2) and an SP boost ratio of 2.25. On the other hand, as shown in Figure 22(b), Example 2 is an example of intermittent reception off mode, that is, block division of each subframe, in which an SP is placed in mobile reception subframe #1, but no SP is placed in fixed reception subframe #2. The SP boost ratio of mobile reception subframe #1 is the same in Comparative Example 2 and Example 2.

[0137] As shown in Figure 23, the reception characteristics of subframe #2 in a fixed reception environment (AWGN multipath) were evaluated. Example 2 shows a 0.1 dB degradation compared to Comparative Example 2, but the transmission capacity is improved by 2.1% because SP (Dx=24, Dy=2) is not included. The 0.1 dB degradation is due to the difference in transmission path estimation accuracy caused by the difference in boost ratio. Therefore, it is thought that these differences can be further reduced by slightly increasing the boost ratio within subframe #1. However, increasing the boost ratio of subframe #1 also affects the transmission characteristics of subframe #1, so it is necessary to use a value that does not cause significant degradation for both subframes #1 and #2.

[0138] As described above, the SP placement means 104 of the transmitting device 100 according to this embodiment places SPs only in a specific subframe (mobile reception subframe #1) among multiple subframes associated with multiple layers within a frame in the intermittent reception off mode. That is, the SP placement means 104 does not place SPs in subframes other than the specific subframe (fixed reception subframe #2). This makes it possible to reduce the proportion of SPs compared to the case where SPs are placed in all subframes, while suppressing the deterioration of reception characteristics, and thereby increasing the transmission capacity.

[0139] (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."

[0140] 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).

[0141] 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]

[0142] 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: Transmission 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 :SP placement means 105: Transmission method 110: Preamble signal generation unit 120:TMCC signal generation section 130a: Subframe #1 component 130b: Subframe #2 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: Transmission path estimation means 205: Equalization means 206: Hierarchical signal processing means 361: SP extraction unit 362: Level Correction Unit 363: Transmission path estimation interpolation unit

Claims

1. A transmitting device used in a broadcasting system that performs hierarchical transmission, SP placement means for arranging SP (Scattered Pilot) within the frame, A time-division multiplexing means for multiplexing signals of multiple layers within the frame by time-division multiplexing, The system includes a transmitting means for transmitting multiplexed signals multiplexed by the time-division multiplexing means, The SP placement means is characterized by placing the SP only in a specific subframe, among a plurality of subframes associated with the plurality of layers, to which transmission parameters having higher transmission tolerance are applied compared to other layers of the plurality of layers.

2. 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 in a distributed manner in the time direction within the frame. The transmitting device according to claim 1, characterized in that the SP placement means places the SP in a block belonging to the specific subframe.

3. The transmission device according to claim 2, characterized in that the time-division multiplexing means places blocks belonging to the specific subframe at at least one of the beginning and end of the data area within the frame.

4. The aforementioned multiple layers include a mobile receiving layer and a fixed receiving layer, The plurality of subframes include a mobile reception subframe associated with the mobile reception layer and a fixed reception subframe associated with the fixed reception layer. The transmitting device according to claim 1, characterized in that the SP placement means places the SP in the mobile receiving subframe as the specific subframe.

5. The system further comprises control signal generation means for generating control signals used for at least one of synchronization and control in broadcast transmission, The transmitting means transmits the multiplexed signal, in which the control signals are further multiplexed. The transmitting device according to any one of claims 1 to 4, characterized in that the control signal includes SP information indicating the presence or absence of the SP for each of the plurality of subframes.

6. The transmitting device according to claim 5, characterized in that the control signal is a preamble signal placed at the beginning of the frame, or a TMCC (Transmission and Multiplexing Configuration and Control) signal following the preamble signal.

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, A time-division multiplexing means for separating a first subframe in which a Scattered Pilot (SP) is placed, and a second subframe in which the SP is not placed, from the multiplexed signal, among the multiple subframes associated with the multiple layers, which are associated with a layer to which transmission parameters having higher transmission tolerance are applied compared to other layers of the multiple layers. A receiving device comprising: transmission path estimation means for performing transmission path estimation for the second subframe using the SP arranged in the first subframe.

8. The time-division multiplexing means separates the multiple blocks obtained by dividing each of the multiple subframes in the time direction, which are distributed in the time direction within the frame, from the multiplexed signal. The receiving device according to claim 7, characterized in that the transmission path estimation means performs the transmission path estimation for a block belonging to the second subframe using the SP arranged in a block belonging to the first subframe.

9. The receiving device according to claim 8, wherein the transmission path estimation means performs the transmission path estimation for the block belonging to the second subframe using the SP located in the block belonging to the first subframe, which is located in at least one of the beginning and end of the data area within the frame.

10. The aforementioned multiple layers include a mobile receiving layer and a fixed receiving layer, The first subframe is a mobile reception subframe associated with the mobile reception layer, The receiving device according to claim 7, characterized in that the second subframe is a fixed receiving subframe associated with the fixed receiving layer.

11. The receiving means receives the control signals multiplexed with the multiplexed signals, which are used for at least one of synchronization and control in broadcast transmission. The receiving device according to any one of claims 7 to 10, characterized in that the control signal includes SP information indicating the presence or absence of the SP for each of the plurality of subframes.

12. The receiving device according to claim 11, characterized in that the control signal is a preamble signal placed at the beginning of the frame, or a TMCC (Transmission and Multiplexing Configuration and Control) signal following the preamble signal.

13. The receiving device according to claim 7, characterized in that the transmission path estimation means performs the transmission path estimation to correct the difference in data power between the first subframe and the second subframe.

14. The receiving device according to claim 7, characterized in that the transmission path estimation means performs transmission path estimation for at least one of the leading and trailing portions of the frame using a preamble signal placed at the beginning of the frame.

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