Modulation device, equalization determination device and program

Abstract

To perform layer transmission in which noise is added to only a specific layer.SOLUTION: A modulation device 1 comprises: a first modulator (100-1) which inputs data by layers and performs OFDM modulation processing on the data by layers; a second modulator (100-2) which inputs noise and the data by layers and performs OFDM modulation processing; an indication part (31) which indicates a noise-added layer to which the noise is added among the layers to the second modulator (100-2); a noise generation part (32) which generates the noise; and an addition part (33, 34) which adds output of the second modulator (100-2) to output of the first modulator (100-1) after level adjustment, wherein the second modulator (100-2) performs the OFDM modulation processing on the data by layers other than the noise and noise-added layer.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a modulation device, an equalization decision device, and a program. [Background technology]

[0002] Multiplexing multiple different signals in the time or frequency direction using OFDM (Orthogonal Frequency Division Multiplexing) waves is widely used mainly in the fields of communication and broadcasting. In the advanced terrestrial television broadcasting system (hereinafter simply referred to as the "advanced system"), similar to the current terrestrial digital broadcasting (ISDB-T: Integrated Service Digital Broadcasting-Terrestrial), the aim is to multiplex multiple services with different transmission tolerances, such as for mobile reception and fixed reception, into one channel using hierarchical transmission technology, that is, hierarchical transmission (see, for example, Non-Patent Document 1). As a method of hierarchical transmission, time division or frequency division multiplexing is adopted. Hereinafter, it is assumed that there are two hierarchical layers in the advanced system, that is, a mobile reception layer (corresponding to one-segment of the current terrestrial digital broadcasting) for vehicle-mounted terminals and the like, and a fixed reception layer (corresponding to full-segment of the current terrestrial digital broadcasting) for each home.

[0003] When transitioning from the current terrestrial digital broadcasting to an advanced system, it becomes necessary to change the transmission frequency of the transmitting station (broadcasting station) depending on the transition situation, i.e., channel repacking is required. The transmission frequencies are reorganized by channel repacking to achieve the final channel system. Generally, channel repacking has a large impact on households that receive a fixed reception hierarchical layer, so the following explanation focuses on the fixed reception hierarchical layer. Of course, it can also be applied to other hierarchical layers.

[0004] When channel repacking is performed, some household receivers may not function as expected by the broadcasting company, resulting in poor reception due to incorrect responses. Households that encounter such a situation are required to take some active measures, such as rescanning the channels, and those that cannot do so will not be able to watch. In such cases, the broadcasting company is forced to prepare a large-scale response to the problem, specifically a call center or individual visits that require a lot of manpower. Therefore, in order to perform channel repacking, it is desirable to have measures in place that allow receivers to achieve this smoothly.

[0005] Therefore, as one of the means for smooth channel repacking in current terrestrial digital broadcasting, a method is known in which noise is added only to the OneSeg mobile reception layer, thereby worsening the C / N (Carrier-to-Noise ratio) of the entire band while minimizing the impact on the fixed reception layer, thereby encouraging the receiver to change channels (see, for example, non-patent document 2). [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] Ministry of Internal Affairs and Communications, "Report of the Working Group on Advanced Terrestrial Digital Broadcasting Systems, Broadcasting System Committee, Information and Communications Technology Subcommittee, Information and Communications Council," [online], [Retrieved August 30, 2023], Internet<URL:https: / / www.soumu.go.jp / main_content / 000879770.pdf> [Non-Patent Document 2] Obata, et al., "Development of a One-Seg Noise Addition Method for Digital Terrestrial Broadcasting Frequency Repacking," Journal of the Institute of Image Information and Television Engineers, vol. 68, no. 1, pp. 1-5, 2014. Summary of the Invention [Problem to be solved by the invention]

[0007] In current terrestrial digital broadcasting, the central segment on the frequency axis is always the OneSeg band, so all that is needed is to add noise to that band at all times, and the algorithm is very simple. On the other hand, in the advanced method, the same layer is not always assigned to a specific frequency range. Therefore, the conventional method of adding noise to a specific frequency range cannot be applied as is.

[0008] In addition, the partial reception band of the advanced method is wider than that of the current OneSeg terrestrial digital broadcasting, accounting for 9 out of 35 segments, and includes data carriers other than those of the hierarchical layer to which noise is to be added. For example, if 3 segments are assigned to hierarchical layer A, the 9-segment partial reception band will include 3 segments of hierarchical layer A and 6 segments of other hierarchical layers. Furthermore, since frequency interleaving may be performed between layers, the conventional method of adding noise to a specific frequency region may result in noise being added to layers to which it is not desired.

[0009] SUMMARY OF THE PRESENT DISCLOSURE In view of the above circumstances, an object of the present invention is to provide a modulation device, an equalization decision device, and a program that are capable of performing hierarchical transmission in which noise is added only to a specific layer. [Means for solving the problem]

[0010] The gist of the present invention for solving the above problems is as follows.

[0011] (1) A modulation device comprising: a first modulator that inputs data for each layer and performs OFDM modulation processing on the data for each layer; a second modulator that inputs noise and the data for each layer and performs OFDM modulation processing; an instruction unit that instructs the second modulator on a noise-addition layer among the layers to which the noise is to be added; a noise generation unit that generates the noise; and an adder unit that adjusts the level of the output of the second modulator and adds it to the output of the first modulator, wherein the second modulator performs OFDM modulation processing on data for each layer other than the noise and the noise-addition layer.

[0012] (2) A modulation device comprising: a symbol generation unit that generates carrier symbols for each layer; an indication unit that indicates whether the layer is a noise-addition layer to which noise is added; a noise addition unit that adds noise only to the carrier symbols of the layer that is indicated by the indication unit to be a noise-addition layer; and an OFDM modulation unit that performs OFDM modulation processing on the carrier symbols after processing by the noise addition unit.

[0013] (3) A modulation device comprising: a symbol generation unit that generates carrier symbols for each layer; an OFDM modulation unit that performs OFDM modulation processing on the carrier symbols to generate an OFDM signal; an indication unit that indicates a noise addition layer to which noise is added among the layers; and a layer-selecting noise addition unit that determines whether the OFDM signal is the noise addition layer and adds noise if it is the noise addition layer.

[0014] (4) An equalization determination device that receives an OFDM signal in which data for each layer is OFDM modulated and a plurality of subframes are time-division multiplexed, the equalization determination device comprising: an equalization unit that performs equalization processing for each subframe; a symbol determination unit that performs symbol determination on the symbols processed by the equalization unit; an OFDM modulation unit that performs OFDM modulation processing on the symbols processed by the symbol determination unit to generate an OFDM signal; a time domain multiplexing unit that multiplexes the subframes processed by the OFDM modulation unit in the time domain; and an indication unit that indicates a noise-addition layer to which noise is added among the layers, wherein the OFDM modulation unit generates an OFDM signal in which noise is added only to the symbols of the layer indicated by the indication unit to be a noise-addition layer.

[0015] (5) An equalization determination device that receives an OFDM signal in which data for each layer has been OFDM modulated and subframes have been frequency division multiplexed, the equalization determination device comprising: an equalization unit that performs equalization processing of the received OFDM signal; a symbol determination unit that performs symbol determination on symbols processed by the equalization unit; an indication unit that indicates a noise addition layer to which noise is added among the layers; a layer selection type noise addition unit that determines whether the symbol is the noise addition layer and, if it is the noise addition layer, adds noise to the symbols processed by the symbol determination unit; and an OFDM modulation unit that performs OFDM modulation processing on the symbols processed by the layer selection type noise addition unit.

[0016] (6) A program for causing a computer to function as the modulation device according to any one of (1) to (3).

[0017] (7) A program for causing a computer to function as the equalization determination device according to (4) or (5). Effect of the Invention

[0018] According to the present invention, it is possible to perform hierarchical transmission in which noise is added only to a specific layer. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a diagram showing an example of a frame configuration in which time division multiplexing is used for hierarchical transmission in an advanced system. [Diagram 2] FIG. 1 is a diagram showing an example of a frame structure in which frequency division multiplexing is used for hierarchical transmission in an advanced system. [Diagram 3] FIG. 1 is a diagram showing an example of a frame configuration when there are two subframes in the advanced system. [Figure 4] 1 is a block diagram showing a configuration example of a modulation device; [Diagram 5] 1 is a block diagram showing an example of the configuration of an equalization determination device of a time division multiplexing system; [Figure 6] 1 is a block diagram showing an example of the configuration of an equalization determination device for a frequency division multiplexing system; [Figure 7] 1 is a block diagram showing an example of the configuration of a modulation device according to a first embodiment. [Figure 8] FIG. 11 is a block diagram showing an example of the configuration of a modulation device according to a second embodiment. [Figure 9] FIG. 11 is a block diagram showing an example of the configuration of a modulation device according to a third embodiment. [Figure 10] FIG. 2 is a diagram showing an example of a frame configuration using time division multiplexing for hierarchical transmission in the present invention. [Figure 11] FIG. 2 is a diagram showing an example of a frame structure using frequency division multiplexing for hierarchical transmission in the present invention. [Figure 12] FIG. 13 is a block diagram showing an example of the configuration of an equalization determination device for a time division multiplexing system according to a fourth embodiment. [Figure 13] FIG. 13 is a block diagram showing an example of the configuration of an equalization determination device for a frequency division multiplexing system according to a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] First, an outline of the signal configuration of the advanced method will be described. Fig. 1 shows an example of the time division multiplexing method. Fig. 2 shows an example of the frequency division multiplexing method. In either case, a frame synchronization signal and a transmission control signal (TMCC: Transmission and Multiplexing Configuration Control) are placed at the beginning of the frame. Then, subframes follow as a data section multiplexed by time division or frequency division. Here, an example is taken where the number of hierarchical layers is two. In time division multiplexing, the mobile reception layer and the fixed reception layer are transmitted in subframes 1 and 2, respectively. In frequency division multiplexing, only one subframe is used, and the mobile reception layer and the fixed reception layer are assigned to layer A and layer B, respectively, and transmitted (for example, layer A:layer B = 9:26). The above is an example of usage, and the present invention is not limited to the number of layers, and the number of layers does not have to be two.

[0021] Fig. 3 shows an example of a frame configuration section when there are two subframes. The subframe is composed of a single or multiple layers having a segment structure. In the case of the time division multiplexing method, the output signals from the transmission line coding sections for each signal section are time division multiplexed to form a signal in which the frame synchronization signal, TMCC, subframe 1, and subframe 2 are time division multiplexed as shown in Fig. 1. For details, see Non-Patent Document 1.

[0022] An example of the configuration of a modulation device is shown in Fig. 4. The modulation device 100 shown in Fig. 4 includes an input I / F (interface) unit 11, a symbol generation unit 12, a symbol processing unit 13, a pilot generation unit 14, an Lch generation unit 15, an OFDM frame configuration unit 16, an IFFT (Inverse Fast Fourier Transform) unit 17, and a GI (Guard Interval) addition unit 18. The number of layers in Fig. 4 is 1 when the signal configuration is in Fig. 1, and only layer A is used, and is 2 when the signal configuration is in Fig. 2, and both layers A and B are used.

[0023] The modulation device 100 inputs data constituting a frame for each layer of a single or multiple systems (layer-specific frame), an Lch frame, and pilot arrangement information via the input I / F unit 11. The modulation device 100 performs OFDM modulation processing on the layer-specific frame to perform hierarchical transmission.

[0024] The symbol generating unit 12 includes primary modulation units 121a, 121b, and 121c, and level adjustment units 122a, 122b, and 122c.

[0025] The primary modulation units 121a, 121b, and 121c convert the corresponding hierarchical frames into FEC (Forward Error Correction) blocks that store error correction codes, and perform energy diffusion processing, BCH encoding processing, LDPC (Low Density Parity Check) encoding processing, bit interleaving processing, and mapping processing to generate carrier symbols and output them to the level adjustment units 122a, 122b, and 122c.

[0026] The level adjustment units 122 a , 122 b , and 122 c adjust the levels of the carrier symbols for each layer and output the adjusted levels to the symbol processing unit 13 .

[0027] The symbol processing unit 13 includes a hierarchical synthesis unit 131 that hierarchically synthesizes carrier symbols of each hierarchy, a band division unit 132 that performs band division processing, a time IL (interleave) unit 133 that performs time IL processing, a frequency IL unit 134 that performs frequency IL processing, and a band synthesis unit 135 that synthesizes signals of each band to form a data segment. The frequency IL unit 134 is mainly composed of three units: "intra-hierarchical interleave", "inter-hierarchical interleave", and "intra-segment interleave".

[0028] The pilot generation unit 14 generates pilots based on the pilot arrangement information and outputs them to the OFDM frame configuration unit 16 .

[0029] The Lch generation unit 15 adds a differential reference bit to the beginning, and then performs DBPSK modulation to generate an Lch signal, and outputs the Lch signal to the OFDM frame configuration unit 16.

[0030] The OFDM frame constructing unit 16 adds the pilot generated by the pilot generating unit 14 and the Lch generated by the Lch generating unit 15 to the data segment, thereby constructing an OFDM frame.

[0031] The IFFT unit 17 receives an FFT clock, performs IFFT processing on the OFDM symbol received from the OFDM frame configuration unit 16, generates a valid symbol signal, and outputs it to the GI addition unit 18. The FFT clock may be generated internally by the modulation device 100. In the case of slave synchronization, the IFFT unit 17 receives an FFT clock transmitted from a performance venue.

[0032] The GI adding unit 18 adds a GI, which is a signal obtained by copying a portion of the end of the effective symbol signal, to the beginning of the effective symbol signal input from the IFFT unit 17, and generates a subframe.

[0033] In terrestrial broadcasting networks, there are not only master stations but also relay stations. In the case of relay stations equipped with a modulator, the system is the same as in Figure 4, but in the case of relay stations using broadcast wave relay, there is no modulator and the received modulated signal is used for retransmission. Many of them are equipped with an equalization judgment device to compensate for quality degradation on the transmission path (for example, see Reference 1). [References 1] Kawashima, et al., "Evaluation of transmission characteristics of an equalization judger for advanced terrestrial television broadcasting systems through laboratory experiments," Journal of the Institute of Image Information and Television Engineers, vol. 45, no. 27, pp. 29-32, 2021

[0034] An example of the configuration of an equalization determination device for the time division multiplexing method is shown in Figure 5. The equalization determination device is installed in a broadcast wave relay station, and corrects (equalizes) distortion in the OFDM signal received from the upper station, removes noise (determination to reproduce the original signal), and retransmits the OFDM signal. Equalization determination device 200 shown in FIG. 5 includes an ADC (A / D converter) unit 41 that performs AD conversion processing on a received OFDM signal, an orthogonal demodulation unit 42 that performs orthogonal demodulation processing, a synchronization reproduction unit 43 that performs synchronization reproduction processing, a frame synchronization signal demodulation unit 44 that demodulates a frame synchronization signal, a frame synchronization signal generation unit 45 that generates a frame synchronization signal, an AFC (Automatic Frequency Control) unit 46 that performs automatic frequency control, a TMCC generation unit 47 that generates a TMCC, a subframe 1 generation unit 49-1 that generates subframe 1, a subframe 2 generation unit 49-2 that generates subframe 2, a time domain multiplexing unit 50 that multiplexes the frame synchronization signal, the TMCC, subframe 1, and subframe 2 in the time domain, an orthogonal modulation unit 51 that performs orthogonal modulation processing, and a DAC (D / A converter) unit 52 that performs DA conversion processing.

[0035] The TMCC generation unit 47 includes a GI removal unit 471 that removes GI, an FFT unit 472 that performs FFT processing, a channel estimation unit 473 that performs channel estimation, an equalization unit 474 that performs equalization processing, a TMCC demodulation unit 475 that demodulates TMCC, a symbol determination unit 476 that determines a symbol, a TMCC modulation unit 477 that modulates TMCC, a signal addition unit 478 that adds TMCC, a pilot generation unit 479 that generates a pilot, a signal addition unit 480 that adds Lch, a pilot insertion unit 481 that inserts a pilot, an IFFT unit 482 that performs IFFT processing, and a GI addition unit 483 that adds a GI.

[0036] The subframe 1 generation unit 49-1 includes a GI removal unit 491-1 that removes a GI, an FFT unit 492-1 that performs FFT processing, a channel estimation unit 493-1 that performs channel estimation, an equalization unit 494-1 that performs equalization processing, a symbol decision unit 495-1 that performs symbol decision processing, a pilot generation unit 496-1 that generates a pilot, a signal addition unit 497-1 that adds an Lch, a pilot insertion unit 498-1 that inserts a pilot, an IFFT unit 499-1 that performs IFFT processing, and a GI addition unit 500-1 that adds a GI. The subframe 2 generation unit 49-2 has the same configuration as the subframe 1 generation unit 49-1 because it performs the same processing as the subframe 1 generation unit 49-1.

[0037] Focusing on the data carrier according to the present invention, in the case of time division multiplexing, subframe 1 and subframe 2 aligned in the time direction are separated at the rear stage of AFC unit 46. Then, FFT processing and equalization processing, etc. are performed in subframe 1 generation unit 49-1 and subframe 2 generation unit 49-2, respectively, and then symbol determination is performed to compensate for quality. Then, IFFT processing, etc. are performed again, and the signals are remultiplexed in the time direction. The signal finally output from equalization determination device 200 is the same as that in FIG. 1.

[0038] An example of the configuration of an equalization judgment device of the frequency division multiplexing method is shown in Fig. 6. The equalization judgment device 210 shown in Fig. 6 includes an ADC unit 61 that performs AD conversion, an orthogonal demodulation unit 62 that performs orthogonal demodulation, an AFC unit 63 that performs automatic frequency control, a GI removal unit 64 that removes GI, an FFT unit 65 that performs FFT processing, a TMCC demodulation unit 66 that demodulates TMCC, a channel estimation unit 67 that performs channel estimation, an equalization unit 68 that performs equalization processing, a frequency DIL unit 69 that performs frequency deinterleaving processing, a symbol judgment unit 70 that performs symbol judgment processing, a frequency IL unit 71 that performs frequency interleaving processing, a pilot generation unit 72 that generates pilots, a signal addition unit 73 that adds Lch, a pilot insertion unit 74 that inserts pilots, an IFFT unit 75 that performs IFFT processing, a GI addition unit 76 that adds GI, an orthogonal modulation unit 77 that performs orthogonal modulation processing, and a DAC unit 78 that performs DA conversion processing.

[0039] In the case of frequency division multiplexing, the signal is processed up to frequency deinterleaving, symbol determination is performed based on TMCC information to compensate for quality, and then frequency interleaving, IFFT, etc. are performed again before being output. The final output signal is the same as that shown in Figure 2.

[0040] Three embodiments of the advanced modulation device according to the present invention will be described below. They are the same for both time division multiplexing and frequency division multiplexing.

[0041] <First embodiment> Fig. 7 shows an example of the configuration of a modulating device according to the first embodiment. The modulating device 1 shown in Fig. 7 includes a first modulator 100-1, a second modulator 100-2, an instruction unit 31, a noise generating unit 32, a level adjusting unit 33, and an adding unit 34. The first modulator 100-1 and the second modulator 100-2 are the same as the modulating device 100 described above. The second modulator 100-2 is a modulator synchronized with the main first modulator 100-1. The first modulator 100-1 and the second modulator 100-2 are synchronized by using a common FFT clock.

[0042] The first modulator 100-1 inputs transmission data as usual via the input I / F unit 11-1 and modulates it as usual. The format of the transmission data is assumed to be, for example, XMI (eXtensible Modulator Interface) (see, for example, Reference 2), but is not limited to this. [Reference 2] Kabutomori, et al., "Verification of broadcasting and communication integration systems with a view to practical application of advanced terrestrial broadcasting," Journal of the Institute of Image Information and Television Engineers, vol. 47, no. 11, pp. 25-28, 2023

[0043] The instruction unit 31 instructs the second modulator 100-2 on the layer to which noise is to be added (hereinafter referred to as the “noise-added layer”). For example, the instruction unit 31 instructs the second modulator 100-2 to select layer A as the noise-added layer among layers A, B, and C.

[0044] The instruction information from the instruction unit 31 may be stored in a non-volatile memory, CD-ROM, etc. in the second modulator 100-2, or may be input from the outside. The external input may be XMI, or IP input from a computer sent to the performance studio or installed at the transmitting station, and is not limited to this. Alternatively, the instruction may be given by a physical switch provided in the second modulator 100-2.

[0045] The noise generator 32 generates dummy data that does not match the first modulator 100-1 and acts as noise for the receiver, such as a PN (Pseudo Random Noise) code.

[0046] The second modulator 100-2 inputs, via the input I / F unit 11-2, noise generated by the noise generator 32 in addition to normal transmission data. The input I / F unit 11-2 inputs only noise instead of normal transmission data to the noise-addition layer instructed by the instructing unit 31. Therefore, the second modulator 100-2 modulates noise instead of transmission data for the noise-addition layer. Noise may or may not be added to the pilot.

[0047] Level adjustment section 33 adjusts the level of the OFDM signal output from second modulator 100-2.

[0048] The adder 34 adds the signal output from the first modulator 100-1 and the signal output from the level adjuster 33 together, and outputs the result as the output of the modulation device 1.

[0049] In this way, the modulation device 1 includes a first modulator 100-1 that inputs data for each layer and performs OFDM modulation processing on the data for each layer, a second modulator 100-2 that inputs noise and the data for each layer and performs OFDM modulation processing, an instruction unit 31 that instructs the second modulator 100-2 on the noise-added layer, a noise generator 32 that generates noise, and an adder 34 that adds the output of the second modulator 100-2, the level of which has been adjusted by a level adjuster 33, to the output of the first modulator 100-1, and the second modulator 100-2 performs OFDM modulation processing on data for each layer other than the noise and the noise-added layer. With this configuration, it is possible to perform hierarchical transmission with noise of any magnitude added to any layer.

[0050] <Second embodiment> Fig. 8 shows a configuration example of a modulation device according to the second embodiment. In this embodiment, a noise addition mechanism is built into the modulation device. The modulation device 2 shown in Fig. 8 includes an instruction unit 19 and noise addition units 20a, 20b, and 20c in addition to the configuration of the modulation device 100 described above.

[0051] The instruction unit 19 instructs the noise addition units 220a, 20b, and 20 as to whether or not the layer is a noise-added layer. The method of retaining the instruction information is the same as in the first embodiment.

[0052] The noise addition units 20a, 20b, and 20c receive instructions from the instruction unit 19 and add noise to the noise-added layers, but do not add noise to layers other than the noise-added layers. The noise to be added only needs to be noise for the receiver, so it can be anything that can disrupt the mapping data that has been first modulated and level-adjusted and aligned. It is also possible to continue adding a DC component that results in the desired noise power. As an example of whitening the band and obtaining an arbitrary average power, the Box-Muller method is described below.

[0053] Generally, noise follows a normal distribution. The Box-Muller method aims to generate pseudo-random numbers that follow a normal distribution based on random numbers generated by a computer or other device. When mutually independent random numbers X and Y are generated by a computer or other device according to a uniform distribution on (0,1), Z1 and Z2 defined by equations (1) and (2) become mutually independent random variables that follow the standard normal distribution N(0,1) with mean 0 and variance 1.

number

[0054] Here, the desired amount of noise for a signal, i.e., the desired C / N [dB], is expressed as the noise variance σ 2 is expressed by equation (3).

number

[0055] Using this, the in-phase and quadrature of the noise are expressed by equations (4) and (5). By adding this value to the signal and then modulating it, the desired C / N ratio can be obtained.

number

[0056] In this way, the modulation device 2 includes a symbol generation unit 12 that generates carrier symbols for each layer, an indication unit 19 that indicates whether or not it is a noise-added layer, noise addition units 20a, 20b, and 20c that add noise only to carrier symbols of the layer indicated by the indication unit 19 to be a noise-added layer, and an OFDM modulation unit (symbol processing unit 13, pilot generation unit 14, Lch generation unit 15, OFDM frame configuration unit 16, IFFT unit 17, and GI addition unit 18) that performs OFDM modulation processing on the carrier symbols processed by the noise addition units 20a, 20b, and 20c. This configuration makes it possible to perform hierarchical transmission with noise of any magnitude added to any layer.

[0057] <Third embodiment> Fig. 9 shows a configuration example of a modulation device according to the third embodiment. In this embodiment, noise is added to the end of the modulation device. The modulation device 3 shown in Fig. 9 includes an instruction unit 21 and a hierarchical selection type noise adding unit 22 in addition to the configuration of the modulation device 100 described above.

[0058] The instruction unit 21 instructs the noise addition layer to the layer selection type noise addition unit 22. The method of holding the instruction information is the same as in the first embodiment.

[0059] The layer selection type noise addition unit 22 judges whether the input OFDM signal is the noise addition layer instructed by the instruction unit 21, and adds noise if it is the noise addition layer. The layer is determined as follows. The cyclic prefix in the frame synchronization signal for synchronous reproduction shown in Figs. 1 and 2 is used for correlation to detect the beginning position of the frame. Then, the TMCC following the frame synchronization signal is demodulated to obtain detailed transmission parameters. From the frame configuration thus determined, in the case of the time division multiplexing method, it is judged whether it is the noise addition layer (subframe) instructed by the instruction unit 21, and if it matches the noise addition layer, noise is added. In the case of the frequency division multiplexing method, it is necessary to follow the procedure of performing FFT again, adding noise only to the relevant frequency band, and then performing IFFT to return it. In contrast, the modulation devices 1 and 2 add noise at the timing when the layers are separated, so it is considered that the circuit scale of the modulation devices 1 and 2 is smaller than that of the modulation device 3.

[0060] Fig. 10 shows an example of a frame structure of the time division multiplexing method of the advanced method according to the present invention. Fig. 11 shows an example of a frame structure of the frequency division multiplexing method of the advanced method according to the present invention. When the layer to which noise is added is layer A (mobile reception layer), the signals finally output by modulation devices 1, 2, and 3 are as shown in Figs. 10 and 11. Noise is added only to layer A marked with diagonal lines, and no noise is added to other layers.

[0061] In a receiver that measures the signal quality C / N over the entire channel band, the C / N of the entire channel band appears to have deteriorated. In a home receiver that receives signals from a transmitter that has added this noise as the main station, if the transmitter transmits radio waves on a new channel, the receiver will switch to receiving the new channel. In a home that is relatively far away from the transmitter, if there is another transmitter with a better C / N that should be received, the receiver will switch to receiving the new channel. According to the present invention, such a state can be intentionally created even in the advanced method, and it becomes possible to change the receiver in the repack target area to receive a new channel or a transmitter signal with appropriate reception signal quality.

[0062] Thus, the modulation device 3 includes a symbol generation unit 12 that generates carrier symbols for each layer, an OFDM modulation unit (symbol processing unit 13, pilot generation unit 14, Lch generation unit 15, OFDM frame configuration unit 16, IFFT unit 17, and GI addition unit 18) that performs OFDM modulation processing on the carrier symbols to generate an OFDM signal, an instruction unit 21 that indicates a noise-addition layer, and a layer-selection noise addition unit 22 that determines whether the OFDM signal is a noise-addition layer or not, and adds noise if it is a noise-addition layer. With this configuration, it is possible to perform hierarchical transmission with noise of any magnitude added to any layer.

[0063] Next, two embodiments of the advanced equalization determination device according to the present invention will be described.

[0064] <Fourth embodiment> Fig. 12 shows an example of the configuration of an equalization determination device of a time division multiplexing system according to the fourth embodiment. The equalization determination device 4 shown in Fig. 12 includes instruction units 501-1 and 501-2 and noise addition units 502-1 and 502-2 in addition to the configuration of the above-mentioned equalization determination device 200. In the case of the time division multiplexing system, the noise addition unit 502-1 is arranged at the output of the subframe 1 generation unit 49-1, and the noise addition unit 502-2 is arranged at the output of the subframe 2 generation unit 49-2.

[0065] The instruction units 501-1 and 501-2 instruct the noise addition units 502-1 and 502-2 as to whether or not the layer is a noise addition layer.

[0066] The noise addition units 502-1 and 502-2 add noise when instructed by the instruction units 501-1 and 501-2. Noise may or may not be added to the pilots. The noise addition units 502-1 and 502-2 may be arranged after the GI addition units 500-1 and 500-2. In that case, since the signal is after IFFT, noise is added on the time axis (time domain).

[0067] In this way, the equalization determination device 4 is an equalization determination device that receives an OFDM signal in which data for each layer is OFDM modulated and a plurality of (two in this embodiment) subframes are time-division multiplexed, and includes equalization units 494-1, 494-2 that perform equalization processing for each subframe, symbol determination units 495-1, 495-2 that perform symbol determination on the symbols processed by the equalization units 494-1, 494-2, and an OFDM modulation unit (parallel unit) that performs OFDM modulation processing on the symbols processed by the symbol determination units 495-1, 495-2 to generate an OFDM signal. The OFDM modulation unit includes a pilot generating unit 496-1, 496-2, a signal adding unit 497-1, 497-2, a pilot inserting unit 498-1, 498-2, an IFFT unit 499-1, 499-2, and a GI adding unit 500-1, 500-2), a time domain multiplexing unit 50 that multiplexes the subframes processed by the OFDM modulation unit in the time domain, and an indication unit 501-1, 501-2 that indicates a noise-added layer, and the OFDM modulation unit generates an OFDM signal in which noise is added only to the symbols of the layer indicated by the indication unit 501-1, 501-2 to be a noise-added layer. The signal output from the equalization determination device 4 is as shown in Fig. 10, and it is possible to perform hierarchical transmission in which noise of any magnitude is added to any layer.

[0068] <Fifth embodiment> An example of the configuration of a time division multiplexing system of an equalization determination device according to the present invention is shown in Fig. 13. The equalization determination device 5 shown in Fig. 13 includes an instruction unit 79 and a layer selection type noise addition unit 80 in addition to the configuration of the equalization determination device 210 described above.

[0069] The instruction unit 79 instructs the layer selection type noise addition unit 80 on the noise addition layer.

[0070] The layer-selecting noise addition unit 80 determines whether the input signal is the noise-addition layer specified by the instruction unit 79, and adds noise if it is the noise-addition layer. Since the immediately preceding symbol decision unit 70 performs symbol decision on the data carriers after frequency deinterleaving on a carrier-by-carrier basis, it is possible to easily determine which layer the data carriers output from the symbol decision unit 70 belong to on a segment-by-segment basis, together with the TMCC demodulation information. A noise addition unit may be provided immediately before the pilot insertion unit 74, and noise may also be added to the pilots.

[0071] In this way, the equalization determination device 5 is an equalization determination device that receives an OFDM signal in which data for each layer is OFDM modulated and subframes are frequency division multiplexed, and includes an equalization unit 68 that performs equalization processing of the received OFDM signal, a symbol determination unit 70 that performs symbol determination of the symbol processed by the equalization unit 68, an instruction unit 79 that indicates the noise addition layer, a layer selection type noise addition unit 80 that determines whether the symbol is a noise addition layer and adds noise to the symbol processed by the symbol determination unit 70 if it is a noise addition layer, and an OFDM modulation unit (frequency IL unit 71, pilot generation unit 72, signal addition unit 73, pilot insertion unit 74, IFFT unit 75, GI addition unit 76, orthogonal modulation unit 77, and DAC unit 78) that performs OFDM modulation processing on the symbol processed by the layer selection type noise addition unit 80. The signal output from the equalization determination device 5 is as shown in FIG. 11, and it is possible to perform hierarchical transmission with noise of any magnitude added to any layer.

[0072] According to the above embodiment, it is possible to add noise only to any desired layer. For example, by adding noise only to the mobile reception layer, it is possible to help achieve smooth channel repacking without affecting the size of the broadcast area defined by the reception availability (or, more precisely, the field strength) of the fixed reception layer or the synchronization signal.

[0073] Furthermore, the present invention can be applied to purposes other than channel repacking. For example, when a station is scheduled to be discontinued or broadcast at reduced power, it is possible to prompt the receiver to change channels before the scheduled discontinuation.

[0074] <Program> A computer capable of executing program instructions can be used to function as the above-mentioned modulation devices 1, 2, 3 and equalization decision devices 4, 5. Here, the computer may be a general-purpose computer, a dedicated computer, a workstation, a PC (Personal Computer), an electronic notepad, etc. The program instructions may be program code, code segments, etc. for performing the necessary tasks.

[0075] The computer includes a processor, a storage unit, an input unit, an output unit, and a communication interface. The processor may be a central processing unit (CPU), a micro processing unit (MPU), a graphics processing unit (GPU), a digital signal processor (DSP), a system on a chip (SoC), or the like, and may be composed of multiple processors of the same type or different types. The processor reads out a program from the storage unit and executes it to control each of the above components and perform various arithmetic processing. At least a part of the processing contents may be realized by hardware. The input unit is an input interface that receives a user's input operation and acquires information based on the user's operation, and is a pointing device, a keyboard, a microphone, or the like. The output unit is an output interface that outputs information, and is a display, a speaker, or the like. The communication interface is an interface for communicating with an external device.

[0076] The program may be recorded on a computer-readable recording medium. By using such a recording medium, the program can be installed on the computer. Here, the recording medium on which the program is recorded may be a non-transitory recording medium. The non-transitory recording medium is not particularly limited, and may be, for example, a CD-ROM, a DVD-ROM, or a USB (Universal Serial Bus) memory. In addition, the program may be in a form that is downloaded from an external device via a network.

[0077] Moreover, the above-mentioned modulation device 1 may be configured with one or more semiconductor chips. This semiconductor chip may be equipped with a CPU that executes a program describing the processing contents for realizing each function of the modulation device 1. The same applies to the modulation devices 2 and 3 and the equalization determination devices 4 and 5.

[0078] Although the above-mentioned embodiment has been described as a representative example, it is obvious to those skilled in the art that many modifications and substitutions can be made within the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited by the above-mentioned embodiment, and various modifications or changes can be made without departing from the scope of the claims. For example, it is possible to integrate multiple building blocks shown in the configuration diagram of the embodiment, or to divide one building block.

[0079] Furthermore, although the embodiment has been described using the advanced system, the present invention is not limited to the advanced system, and can be applied to any system that uses OFDM waves, whether it be communications or broadcasting. [Explanation of symbols]

[0080] 1,2,3,100 Modulator 4,5,200,210 Equalization judgment device 11, 11-1, 11-2 Input I / F section 12, 12-1, 12-2 Symbol generation section 13, 13-1, 13-2 Symbol processing section 14, 14-1, 14-2, 72, 479, 496-1, 496-2 Pilot Generation Unit 15,15-1,15-2 Lch generation section 16, 16-1, 16-2 OFDM frame configuration section 17,17-1,17-2,75,482,499-1,499-2 IFFT section 18, 18-1, 18-2, 76, 483, 500-1, 500-2 GI Addition 19,21,31,79,501-1,501-2 Instruction part 20a, 20b, 20c, 502-1, 502-2 Noise adding section 22,80 Hierarchical selection type noise addition unit 32 Noise Generation Unit 33 Level adjustment section 34 Addition section 41,61 ADC section 42,62 Quadrature demodulation section 43 Synchronous playback section 44 Frame sync signal demodulation section 45 Frame sync signal generator 46,63 AFC section 47 TMCC generation section 49-1 Subframe 1 generation unit 49-2 Subframe 2 Generation Unit 50 time domain multiplex section 51,77 Quadrature modulation section 52,78 DAC section 69 Frequency DIL section 71,134,134-1,134-2 Frequency IL section 64,471,491-1,491-2 GI removal part 65,472,492-1,492-2 FFT section 67,473,493-1,493-2 Channel Estimation Unit 68,474,494-1,494-2 Equalization section 66,475 TMCC demodulation section 70,476,495-1,495-2 Symbol decision section 73,478,480,497-1,497-2 Signal adding section 74,481,498-1,498-2 Pilot Insertion Part 100-1 1st modulator 100-2 Second modulator 121a, 121b, 121c, 121a-1, 121b-1, 121c-1, 121a-2, 121b-2, 121c-2 Primary modulation section 122a, 122b, 122c, 122a-1, 122b-1, 122c-1, 122a-2, 122b-2, 122c-2 Level adjustment section 131, 131-1, 131-2 Hierarchical synthesis section 132, 132-1, 132-2 Band division section 133,133-1,133-2 Time IL Department 135, 135-1, 135-2 Band synthesis section 477 TMCC Modulation Section

Claims

1. a first modulator which receives data for each layer and performs OFDM modulation processing on the data for each layer; a second modulator that receives noise and the data for each layer and performs OFDM modulation processing; an instruction unit that instructs the second modulator on a noise addition layer to which the noise is to be added among the layers; A noise generator that generates the noise; an adder that adjusts the level of an output of the second modulator and adds the output of the first modulator to the output of the second modulator; Equipped with The second modulator performs OFDM modulation processing on data for each layer other than the noise and the noise-added layer.

2. a symbol generation unit that generates carrier symbols for each layer; An indication unit for indicating whether the layer is a noise addition layer to which noise is added; a noise addition unit that adds noise only to the carrier symbols of a layer that is designated as a noise-added layer by the designation unit; an OFDM modulation unit that performs OFDM modulation processing on the carrier symbols processed by the noise addition unit; A modulation device comprising:

3. a symbol generation unit that generates carrier symbols for each layer; an OFDM modulation unit that performs OFDM modulation processing on the carrier symbols to generate an OFDM signal; An indication unit that indicates a noise addition layer to which noise is to be added among the layers; a layer selection type noise addition unit that determines whether the OFDM signal is the noise-added layer and adds noise if the OFDM signal is the noise-added layer; A modulation device comprising:

4. An equalization determination device for receiving an OFDM signal in which data for each layer is OFDM modulated and a plurality of subframes are time-division multiplexed, the device comprising: an equalization unit that performs equalization processing for each subframe; a symbol determination unit that performs symbol determination on the symbols processed by the equalization unit; an OFDM modulation unit that performs OFDM modulation processing on the symbols processed by the symbol determination unit to generate an OFDM signal; a time domain multiplexing unit that multiplexes the subframes processed by the OFDM modulation unit in a time domain; An instruction unit that indicates a noise addition layer to which noise is to be added among the layers, The OFDM modulation unit generates an OFDM signal to which noise has been added only to symbols of a layer designated by the designation unit as a noise-added layer.

5. 1. An equalization determination device for receiving an OFDM signal in which data for each layer is OFDM modulated and subframes are frequency division multiplexed, comprising: an equalization unit that performs equalization processing on a received OFDM signal; a symbol determination unit that performs symbol determination on the symbols processed by the equalization unit; An indication unit that indicates a noise addition layer to which noise is to be added among the layers; a layer selection type noise addition unit that determines whether the symbol is the noise addition layer, and adds noise to the symbol processed by the symbol determination unit if the symbol is the noise addition layer; an OFDM modulation unit that performs OFDM modulation processing on the symbols processed by the hierarchical selection type noise addition unit; An equalization determination device comprising:

6. A program for causing a computer to function as the modulation device according to any one of claims 1 to 3.

7. A program for causing a computer to function as the equalization determination device according to claim 4 or 5.

Images