JP2022038506A - Transmission device, relay device, and receiving device - Google Patents

Abstract

To suppress the error of a retransmitted signal received under the condition of high area reception C/N by a receiving device without adding noise to a signal by a relay device.SOLUTION: A degenerate amount information generation unit 24 of a relay device 2-1 obtains degenerate amount information from a relay station reception C/N using a predetermined function. The relay device 2-1 transmits a broadcast wave including a main line signal, degenerate amount information, and TxID of the relay device 2-1. An LLR processing unit 33 of a receiving device 3-1 estimates a noise variance estimated value σ2 from an equalization signal, adjusts the noise variance estimated value σ2 on the basis of the degenerate amount information extracted from the equalization signal, obtains a noise variance adjustment value σ'2, and calculates an LLR on the basis of the equalization signal and the noise variance adjustment value σ'2. As a result, the noise variance adjustment value σ'2 can be set to a large value under the condition that the relay station reception C/N is low and the area reception C/N is high, and the LLR can be degenerated.SELECTED DRAWING: Figure 3

Description

The present invention relates to a digital signal transmitting device, a relay device, and a receiving device, and more particularly to a technique for suppressing data errors in a system that relays a broadcast wave of digital broadcasting, determines a symbol, and receives a retransmitted signal. ..

Conventionally, a digital broadcasting system that employs an LDPC code, which is a high-performance error correction code, has been standardized, and actual broadcasting has already been performed in some countries. The LDPC code is a block code characterized by a low density of "1" in the parity check matrix and a long code length, and is known to obtain performance close to the Shannon limit.

In conventional terrestrial digital broadcasting, a convolution code is used for the internal code and a read solomon code is used for the external code. However, since the LDPC code was put into practical use, a new method using the LDPC code for the internal code and the BCH code for the external code Proposals are being made one after another. By using a high-performance LDPC code, it is possible to increase the number of symbol modulation multi-values and improve the transmission rate.

Examples of the broadcasting system using the LDPC code include an advanced wideband satellite digital broadcasting system, DVB-S2, DVB-T2, DVB-NGH and the like. The DVB-T2 is a European terrestrial digital broadcasting system using an LDPC code, and a non-regular LDPC code having a code length of 64,800 bits is adopted.

In Japan, terrestrial digital broadcasting by ISDB-T is being carried out. ISDB-T, like DVB-T2, is a method based on orthogonal frequency division multiplexing (OFDM), and a convolutional code is used as the internal code.

Also in Japan, a next-generation terrestrial digital broadcasting system using an LDPC code has been proposed (see, for example, Non-Patent Document 1). In the current ISDB-T, 64QAM that transmits 6 bits with one symbol is adopted in the fixed reception layer, but 256QAM that transmits 8 bits with one symbol, 1024QAM that transmits 10 bits, and 4096QAM that transmits 12 bits. Etc. are examined, and it is expected that the transmission capacity will be expanded.

In Japan, many relay stations are installed to deliver the radio waves of terrestrial digital broadcasting all over the country, and many of the relay stations receive, amplify, and retransmit the radio waves of higher-level stations as a relay method. Broadcast wave relay is adopted.

The relay device installed in the relay station not only simply receives the radio waves transmitted from the higher-level station, amplifies and retransmits them, but also equalizes the multipath distortion contained in the received radio waves. And some have a function of removing noise components by determination processing. Such a relay device is useful for reducing signal quality deterioration in multi-stage relay.

FIG. 27 is a block diagram showing an overall configuration example of a terrestrial broadcasting system including a conventional transmitting device, a relay device, and a receiving device. This terrestrial broadcasting system shows a configuration in the case of relaying a broadcast wave, and uses an LDPC code as an error correction code. The terrestrial broadcasting system includes a transmitting device 100 provided in the master station, a relay device 200 provided in the relay station, and a receiving device 300 provided in a general household.

The transmission device 100 applies LDPC coding to the broadcast signal by the LDPC coding unit 101, modulates the bit series after LDPC coding by the modulation unit 102, and transmits the broadcast wave. The broadcast wave from the transmission device 100 is transmitted to the relay device 200 via the transmission line 150 between the transmission device 100 and the relay device 200.

The relay device 200 receives the broadcast wave transmitted from the transmission device 100, equalizes the received signal to the transmission line equalization unit 201 by the transmission line equalization unit 201, and uses the symbol determination unit 202 to convert the received signal into the signal after the transmission line equalization. The symbol determination is performed, and the remodulation unit 203 remodulates the signal after the symbol determination. Then, the relay device 200 retransmits the broadcast wave. The broadcast wave from the relay device 200 is transmitted to the receiving device 300 via the transmission line 250 between the relay device 200 and the receiving device 300.

The receiving device 300 receives the broadcast wave retransmitted from the relay device 200, performs transmission line equalization on the received signal by the transmission line equalization unit 301, and LLR (log likelihood ratio) calculation unit. The LLR is calculated from the signal after equalization of the transmission line at 302, and the LLR is decoded by the LDPC decoding unit 303. This makes it possible to restore the original broadcast signal.

In addition, in a terrestrial broadcasting system, when designing a broadcasting area by installing a relay station, a method is studied in which each transmitting station multiplexes the TxID (identification signal) of its own station (unique to the transmitting station) to the transmission signal and transmits it. Has been done. By using this TxID, the receiving device can identify from which transmitting station the received signal is transmitted. The TxID is a signal for identifying the transmitting station.

FIG. 28 is a block diagram showing an overall configuration example of a terrestrial broadcasting system assuming transmission / reception of TxID. This terrestrial broadcasting system is a terrestrial broadcasting system shown in FIG. 27 with a function of transmitting and receiving TxID added. The terrestrial broadcasting system includes a transmitting device 110 provided in the master station, a relay device 210 provided in the relay station, and a receiving device 310 provided in a general household.

The transmission device 110 generates the TxID of its own station by the TxID generation unit 103, and modulates the TxID by the modulation unit 104. Then, the transmission device 110 synthesizes the modulated signal of the broadcast signal generated by the LDPC coding unit 101 and the modulation unit 102 by multiplexing the modulated signal of TxID, and transmits the broadcast wave. The broadcast wave from the transmission device 110 is transmitted to the relay device 210 via the transmission line 150.

The relay device 210 generates the TxID of its own station by the TxID generation unit 204, and modulates the TxID by the modulation unit 205. Then, the relay device 210 synthesizes the modulated signal of the broadcast signal generated by the transmission line equalization unit 201, the symbol determination unit 202, and the remodulation unit 203 by multiplexing the TxID modulated signal, and regenerates the broadcast wave. Send. The broadcast wave from the relay device 210 is transmitted to the receiving device 310 via the transmission line 250.

The receiving device 310 receives the broadcast wave retransmitted from the relay device 210, and outputs the original broadcast signal obtained by the transmission line equalization unit 301, the LLR calculation unit 302, and the LDPC decoding unit 303. Further, the receiving device 310 extracts the TxID modulated signal from the received signal by the TxID extraction unit 304 and demodulates the TxID modulated signal to obtain the TxID of the transmission source of the received signal. As a result, the receiving device 310 can recognize from which transmitting station the received signal is transmitted.

"Transmission Technology for Advanced Terrestrial Broadcasting Special Issue", NHK Technology R & D, No. 172, published in November 2018, p2-p47

In the terrestrial broadcasting system shown in FIGS. 27 and 28, receiving the broadcast wave transmitted from the transmission devices 100 and 110 of the master station, which is the higher station, by the relay devices 200 and 210 of the relay station is referred to as higher station reception. .. When the relay devices 200 and 210 receive the signal at the higher station, the ratio (C / N ratio) between the signal power of the received signal and the power of the white Gaussian noise is called the relay station reception C / N.

Further, receiving the broadcast wave retransmitted from the relay devices 200 and 210 of the relay station by the receiving devices 300 and 310 is called area reception. When the receiving devices 300 and 310 receive area reception, the ratio (C / N ratio) between the signal power of the received signal and the power of white Gaussian noise is referred to as area reception C / N.

Here, since the relay station reception C / N is low, it is assumed that a symbol error occurs in the relay devices 200 and 210. In this case, when the area reception C / N is sufficiently higher than the required C / N, the LLR (initial LLR) initially given to the LDPC decoding process in the receiving devices 300 and 310 becomes a high value. Then, there is a high possibility that the symbol error will be reflected in the decoding result as it is, and as a result, the erroneous signal may be restored.

The LDPC code decoding process by the receiving devices 300 and 310 is a process of improving the LLR of the entire bit of the LDPC code by repeatedly exchanging the LLR of each bit between the bit node and the check node. Therefore, in order to fully demonstrate the correction ability, the initial LLR given first is important. This initial LLR is obtained from the distance between the received signal point and the constellation point, and the noise dispersion in area reception. When the area reception C / N is high, the noise dispersion becomes small and the initial LLR becomes a high value.

When the relay devices 200 and 210 perform the symbol hardness determination, the signal points of the received signals of the relay devices 200 and 210 are remapped to the nearest constellation points. Therefore, when the relay station reception C / N is low, it may be remapped to a point different from the signal point of the transmission signal from the transmission devices 100 and 110. This means that the repeaters 200, 210 will retransmit the erroneous signal.

When the receiving devices 300 and 310 receive this signal in the high area reception C / N, the decoding process is started in a state where the initial LLR of all bits is high, and the LDPC decoding unit 303 determines the erroneously determined signal. Can't.

As described above, in the terrestrial broadcasting system shown in FIGS. 27 and 28, there is a problem that an error occurs in the receiving devices 300 and 310 even though the area reception C / N is high.

In order to solve such a problem, it is assumed that a method (soft determination) for determining a symbol based on LLR is used in the relay devices 200 and 210. By using the soft determination, it is possible to reduce the error even when the area reception C / N is high. However, this method cannot completely suppress errors.

Further, a method of adding noise to data (for example, TMCC, LLch) used for noise dispersion estimation among the signals retransmitted by the relay devices 200 and 210 has been proposed (the same applicant of the present patent application). (See Japanese Patent Application No. 2019-195792, which was unpublished at the time of filing the patent application filed in Japan).

By adding noise to TMCC, LLch, etc. used for noise dispersion estimation, the area reception C / N can be intentionally lowered and the LLR can be degenerated (the absolute value of the LLR can be reduced). By degenerating the LLR, the symbol error may be overturned in the LDPC decoding process, and as a result, the error can be suppressed in a state where the area reception C / N is high. However, the relay devices 200 and 210 need to be provided with a circuit for adding noise, and the transmission characteristics of TMCC, LLch and the like are deteriorated.

Therefore, the present invention has been made to solve the above-mentioned problems, and an object of the present invention is to receive a transmission device for transmitting a broadcast wave and a broadcast wave transmitted from the transmission device, determine a symbol, and retransmit. In a terrestrial broadcasting system including a relay device and a receiving device that receives a broadcast wave retransmitted from the relay device, the receiving device performs an area reception C / N without adding noise to the signal. It is an object of the present invention to provide a transmitting device, a relay device, and a receiving device capable of suppressing an error in a retransmitted signal received under high conditions.

In order to solve the above-mentioned problem, the transmitting device according to claim 1 is a transmitting device that performs LDPC coding on a broadcast signal, modulates the signal after LDPC coding, and transmits the broadcast wave of the main line signal. A reduction amount information generation unit that generates information on the reduction of the LLR when the receiving device that receives the wave calculates the LLR (log-like probability ratio) as the reduction amount information, and the reduction amount information generation unit that generates the information. A modulation unit that modulates the reduction amount information to generate a reduction amount information signal, a synthesis unit that synthesizes the main line signal and the reduction amount information signal generated by the modulation unit, and a synthesis unit synthesized by the synthesis unit. The shrinkage amount information indicating that the shrinkage processing off is provided with a transmission unit for transmitting the broadcast wave including the main line signal and the shrinkage amount information signal, and the shrinkage amount information generation unit does not perform the shrinkage processing for the LLR. It is characterized by producing.

Further, the relay device according to claim 2 receives the broadcast wave transmitted from the transmission device, performs transmission line equalization on the signal of the broadcast wave, performs symbol determination on the signal after transmission line equalization, and performs symbol determination. In a relay device that remodulates a later signal and retransmits a broadcast wave of a main line signal, the C / N ratio in the relay device is set as a relay station reception C / N based on the signal after equalization of the transmission path. Using the relay station reception C / N estimation unit to be estimated and a predetermined function or table, the data corresponding to the relay station reception C / N estimated by the relay station reception C / N estimation unit is used as the broadcast wave. The withdrawal amount information generation unit generated as the withdrawal amount information regarding the withdrawal of the LLR when the receiving device receiving the LLR (log-like likelihood ratio) calculates, and the withdrawal amount information generated by the withdrawal amount information generation unit. A modulation unit that modulates the main line signal to generate a reduction amount information signal, a synthesis unit that synthesizes the main line signal and the reduction amount information signal generated by the modulation unit, and the main line signal synthesized by the synthesis unit. And, the transmission unit for transmitting the broadcast wave including the reduction amount information signal is provided, and the higher the relay station reception C / N of the reduction amount information generation unit, the lower the degree of the reduction of the LLR. Therefore, the lower the relay station reception C / N is, the higher the degree of decompression of the LLR is, and the depletion amount information is generated.

Further, the relay device according to claim 3 is the relay device according to claim 2, wherein the reduction amount information generation unit uses the receiving device to equalize the LLR to the signal and noise dispersion adjustment value σ ' ² . As a process of degrading the LLR when calculating from, the noise dispersion addition value σ ² _add is added to the noise dispersion estimated value σ ² estimated from the signal after the transmission path equalization, and the noise dispersion adjustment value σ ' ² When the addition method for obtaining the relay station is used, the higher the relay station reception C / N, the smaller the noise dispersion addition value σ ² _add , and the lower the relay station reception C / N, the noise dispersion. The noise dispersion added value σ ² _add is generated as the reduction amount information so that the addition value σ ² _add becomes large, and the noise dispersion estimated from the signal after the transmission path equalization is performed as a process of reducing the LLR. When the estimated value σ ² is the noise dispersion clip value σ ² _clip or more, the noise dispersion estimated value σ ² is set as the noise dispersion adjustment value σ ' ² , and the noise dispersion estimated value σ ² is the noise dispersion clip value σ ² _clip . When it is less than, when the clip processing in which the noise dispersion clip value σ ² _clip is set to the noise dispersion adjustment value σ ' ² is used, the higher the relay station reception C / N, the more the noise dispersion clip value σ ² The noise dispersion clip value σ ² _clip is generated as the reduction amount information so that the _clip becomes smaller and the relay station reception C / N becomes lower, the noise dispersion clip value σ ² _clip becomes larger. It is characterized by.

Further, in the relay device according to claim 4, in the relay device according to claim 2, the relay station receiving C / N estimation unit relays the entire band based on the signal after the transmission line is equalized. The station reception C / N or the relay station reception C / N for each segment is estimated, and the reduction amount information generation unit estimates by the relay station reception C / N estimation unit using the predetermined function or table. The data corresponding to the relay station reception C / N in the entire band is generated as the reduction amount information in the entire band, or the data corresponding to the relay station reception C / N in each segment is generated. It is characterized in that it is generated as the shrinkage amount information for each segment.

Further, the receiving device according to claim 5 receives broadcast waves transmitted from the transmitting device and the relay device, respectively, applies transmission line equalization to the broadcast wave signal, and LLR (log number) from the signal after the transmission line equalization. In a receiving device that calculates the likelihood ratio) and performs LDPC decoding to restore the broadcast signal, an extraction unit that extracts a reduction amount information signal from the broadcast wave signal and the reduction amount information extracted by the extraction unit. It is provided with a demodulator that demolishes a signal to obtain information on the amount of shrinkage, and an LLR processing unit that calculates the LLR based on the signal after equalization of the transmission path and the information on the amount of shrinkage obtained by the demodulator. , The LLR processing unit is estimated by the noise dispersion estimation unit that estimates the noise dispersion estimation value σ ² based on the signal after the transmission path equalization, and the noise dispersion estimation unit based on the reduction amount information. The noise dispersion adjustment unit that adjusts the noise dispersion estimated value σ ² to obtain the noise dispersion adjustment value σ ' ² , the signal after the transmission path equalization, and the noise dispersion adjustment value σ obtained by the noise dispersion adjustment unit. The LLR calculation unit that calculates the LLR based on ' ² is provided, and the reduction amount information when the broadcast wave transmitted from the transmission device is received is not processed to reduce the LLR. The data indicating the processing off is used, and the reduction amount information when the broadcast wave transmitted from the relay device is received, the higher the relay station reception C / N, which is the C / N ratio in the relay device, the higher. The noise dispersion adjusting unit is used as data indicating the degree to which the LLR is reduced so that the degree to which the LLR is reduced is low and the lower the relay station reception C / N is, the higher the degree to which the LLR is reduced is. However, when the shrinkage amount information indicates that the shrinkage processing is off, the noise dispersion estimated value σ ² is set as the noise dispersion adjustment value σ ' ² , and the shrinkage amount information indicates the degree to which the LLR is retracted. In this case, the noise dispersion adjustment value σ ' ² that reflects the degree of decompression of the LLR is obtained.

Further, in the receiving device according to claim 6, the receiving device according to claim 6 uses the addition method as a process in which the noise dispersion adjusting unit reduces the LLR, and the transmitting device and the relay device make noise. When the dispersion addition value σ ² _add is generated as the reduction amount information, the noise dispersion addition value σ ² _add is added to the noise dispersion estimated value σ ² , the noise dispersion adjustment value σ ' ² is obtained, and the LLR is obtained. When the noise dispersion clip value σ ² _clip is generated as the regression amount information by the transmission device and the relay device, the noise dispersion estimated value σ ² is the noise dispersion clip. When the value is σ ² _clip or more, the noise dispersion estimated value σ ² is set as the noise dispersion adjustment value σ ' ² , and when the noise dispersion estimated value σ ² is less than the noise dispersion clip value σ ² _clip , the noise dispersion clip. It is characterized in that the value σ ² _clip is set to the noise dispersion adjustment value σ ' ² .

Further, the transmitting device according to claim 7 applies LDPC coding to the broadcast signal, modulates the signal after LDPC coding to generate a main line signal, and modulates the TxID (identification signal) of its own device. In a transmission device that generates a TxID after modulation and transmits a broadcast wave that combines the main line signal and the TxID after modulation, the C / estimated by the relay device that receives the broadcast wave transmitted from the transmission device. The relay station reception C / N, which is the N ratio, and the TxID of the relay device are received from the relay device, the broadcast wave transmitted from the transmission device, and the broadcast wave retransmitted from the relay device. When the receiving device that receives the LLR calculates the LLR (log likelihood ratio), it does not perform the processing to reduce the LLR. It generates the reduction amount information indicating the reduction processing off, and uses a predetermined function or table to generate the reception unit. The higher the relay station reception C / N received by the broadcaster, the lower the degree of deceleration of the LLR, and the lower the relay station reception C / N, the higher the degree of decompression of the LLR. In addition, the shrinkage amount information indicating the degree of shrinkage of the LLR is generated, the TxID of the transmission device, the shrinkage amount information indicating the shrinkage processing off corresponding to the TxID, and the TxID and the TxID of the relay device. A broadcast signal that generates the broadcast signal including the correspondence table generated by the correspondence table generation unit and the correspondence table generation unit that generates the correspondence table including the reduction amount information indicating the degree of reduction of the LLR corresponding to the above. A generation unit, a synthesis unit that synthesizes the main line signal generated by subjecting the broadcast signal generated by the broadcast signal generation unit to the LDPC coding and the modulation, and the TxID after the modulation, and the above. It is characterized by including a transmission unit for transmitting the main line signal synthesized by the synthesis unit and the broadcast wave including the TxID.

Further, in the transmission device according to claim 8, the broadcast signal generation unit stores the corresponding table in the data broadcasting area of fixed reception and partial reception of the broadcast signal, and the transmission device is described. It is characterized in that the broadcast signal including the corresponding table is generated.

Further, the receiving device according to claim 9 receives the broadcast wave transmitted from the transmitting device and the relay device according to claim 7, respectively, applies a transmission line equalization to the signal of the broadcasting wave, and after the transmission line equalization. In a receiving device that calculates LLR (log likelihood ratio) from the signal of the above and performs LDPC decoding to restore the broadcast signal, the TxID (identification signal) of the transmitting device and the TxID of the relay device are obtained from the signal of the broadcast wave. The shrinkage amount corresponding to the TxID extracted by the extraction unit from the extraction unit to be extracted and the corresponding table restored by performing LDPC decoding by calculating LLR from the signal after equalization of the transmission line. It is provided with a reduction amount information reading unit for reading information, and an LLR processing unit for calculating the LLR based on the signal after the transmission line equalization and the reduction amount information read by the reduction amount information reading unit. The LLR processing unit uses the noise dispersion estimation unit that estimates the noise dispersion estimation value σ ² based on the signal after the transmission line equalization, and the reduction amount information read by the reduction amount information reading unit. Based on this, the noise dispersion adjustment unit that adjusts the noise dispersion estimation value σ ² estimated by the noise dispersion estimation unit to obtain the noise dispersion adjustment value σ ' ² , the signal after the transmission line equalization, and the noise dispersion. A LLR calculation unit that calculates the LLR based on the noise dispersion adjustment value σ ' ² obtained by the adjustment unit is provided, and the noise distribution adjustment unit indicates that the reduction amount information indicates that the reduction process is off. In this case, the noise dispersion estimated value σ ² is set to the noise dispersion adjustment value σ ' ² , and when the shrinkage amount information indicates the degree of shrinkage of the LLR, the noise dispersion estimation reflects the degree of shrinkage of the LLR. It is characterized by finding the value σ ² .

As described above, according to the present invention, the transmission device that transmits the broadcast wave, the relay device that receives the broadcast wave transmitted from the transmission device, determines the symbol, and retransmits the broadcast wave, and the relay device retransmits the broadcast wave. In a terrestrial broadcasting system configured to include a receiving device for receiving a broadcast wave, the retransmitted signal received by the receiving device under a high area reception C / N condition without adding noise to the signal by the relay device. Errors can be suppressed.

It is a schematic diagram which shows the whole configuration example of the terrestrial broadcasting system which comprises the transmitting device, the relay device and the receiving device of Examples 1 and 2. It is a block diagram which shows the structural example of the transmission apparatus of Example 1. FIG. It is a block diagram which shows the structural example of the relay apparatus of Example 1. FIG. It is a flowchart which shows the processing example of the degenerate amount information generation part. It is a figure which shows an example of the relationship between the relay station reception C / N and the noise dispersion addition value σ ² _add (C / N conversion value). It is a figure which shows an example of the relationship between a relay station reception C / N and a noise dispersion clip value σ ² _clip (C / N conversion value). It is a block diagram which shows the structural example of the receiving apparatus of Example 1. FIG. It is a block diagram which shows the structural example of the LLR processing part. It is a flowchart which shows the processing example of the LLR processing part. It is a figure explaining the process (in the case of an addition method) of the 1st configuration example of a noise dispersion adjustment part. It is a figure which shows the noise dispersion adjustment value ^σ'2 (in the case of an addition method) obtained by the 1st configuration example of a noise dispersion adjustment part. It is a figure explaining the processing (in the case of a clip method) of the 2nd configuration example of a noise dispersion adjustment part. It is a figure which shows the relationship between the noise dispersion estimated value σ 2 input by the 2nd configuration example of a noise dispersion adjustment part, and the noise dispersion adjustment value σ ' ² (in the case of a clip method) output. It is a figure which shows the noise dispersion adjustment value ^σ'2 (in the case of a clip method) obtained by the 2nd configuration example of a noise dispersion adjustment part. It is a block diagram which shows the configuration example of the transmission apparatus of Example 2. It is a flowchart which shows the processing example of the correspondence table generation part. It is a figure which shows the example of the correspondence table (in the case of an addition method). It is a figure which shows the example of the correspondence table (in the case of a clip method). It is a block diagram which shows the configuration example of the relay device of Example 2. It is a block diagram which shows the configuration example of the receiving apparatus of Example 2. It is a flowchart which shows the processing example of the degenerate amount information reading part. It is a figure which shows the simulation system. It is a figure which shows the simulation specification (in the case of an addition method). It is a figure which shows the BER characteristic (in the case of an addition method) obtained by a simulation. It is a figure which shows the simulation specifications (in the case of a clip method). It is a figure which shows the BER characteristic (in the case of a clip method) obtained by a simulation. It is a block diagram which shows the whole configuration example of the terrestrial broadcasting system which is configured with the conventional transmission device, the relay device and the receiving device. It is a block diagram which shows the whole structure example of the terrestrial broadcasting system when the transmission and reception of TxID are assumed.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. The first embodiment of the present invention is characterized in that the transmitting device and the relay device generate and transmit the degenerate amount information, and the receiving device degenerates the LLR based on the degenerate amount information. Further, in the second embodiment of the present invention, the transmitting device generates and transmits a corresponding table including the degenerate amount information for each of the transmitting device and the relay device, and the receiving device transmits the received signal from the corresponding table. It is characterized in that the degenerate amount information corresponding to the TxID is read out and the LLR is degenerated based on the degenerate amount information.

Here, degenerating LLR means reducing the absolute value of LLR. When the absolute value of LLR is large, it means that the probability of bit value 0 or 1 is high, and when the absolute value of LLR is small, it means that the probability of bit value 0 or 1 is low.

By degenerating LLR, the absolute value of LLR becomes small, and the probability of its bit value 0 or 1 becomes low. When the LDPC decoding process is performed using the LLR in such an ambiguous state, the symbol error may be overturned and the error may be corrected.

As a result, it is possible to suppress an error in the retransmitted signal received by the receiving device under a high area reception C / N situation without adding noise to the data used by the relay device for noise dispersion estimation.

[Ground broadcasting system]
FIG. 1 is a schematic diagram showing an overall configuration example of a terrestrial broadcasting system including a transmitting device, a relay device, and a receiving device of the first and second embodiments. This terrestrial broadcasting system includes a transmitting device 1 provided in a master station, a relay device 2 provided in a relay station, and a receiving device 3 provided in a general household.

This terrestrial broadcasting system applies a method of multiplexing TxID by the terrestrial broadcasting system shown in FIG. 28 to a main line signal. In the first embodiment, the degenerate amount information is transmitted from the transmitting device and the relay device to the receiving device, and in the second embodiment, the corresponding table including the TxID and the degenerate amount information is transmitted from the transmitting device to the receiving device.

[Example 1]
First, Example 1 will be described. As described above, the first embodiment is an example in which the transmitting device and the relay device generate and transmit the degenerate amount information, and the receiving device degenerates the LLR based on the degenerate amount information.

[Master Station / Transmitter 1 / Example 1]
First, the transmission device 1 provided in the master station in the first embodiment will be described. FIG. 2 is a block diagram showing a configuration example of the transmission device 1 of the first embodiment. The transmission device 1-1 includes an LDPC coding unit 10, a modulation unit 11, 15, a degenerate amount information generation unit 12, a TxID generation unit 13, a multiplex information generation unit 14, and a synthesis unit 16.

The LDPC coding unit 10 inputs a broadcast signal, performs LDPC coding on the broadcast signal, and outputs the signal after LDPC coding to the modulation unit 11. The modulation unit 11 inputs the signal after LDPC coding from the LDPC coding unit 10, modulates the signal after LDPC coding, and outputs the modulated signal as a main line signal to the synthesis unit 16.

The degeneration amount information generation unit 12 has preset degeneration amount information indicating that degeneration processing is not performed (degeneration processing is off) (noise dispersion addition value σ ² _add = 0 when the degeneration method is the addition method, clip method). In this case, the noise dispersion clip value σ ² _clip = 0) is generated as the degeneracy amount information of the master station. Then, the degenerate amount information generation unit 12 outputs the degenerate amount information to the multiplex information generation unit 14. The degeneracy amount information is information regarding the degeneracy of the LLR when the receiving device 3-1 described later calculates the LLR.

Here, it is assumed that whether the degenerate method is the addition method or the clip method is preset in the terrestrial broadcasting system. The noise dispersion addition value σ ² _add = 0 or the noise dispersion clip value σ ² _clip = 0 indicates the degeneration processing off in which the noise dispersion is not adjusted when calculating the LLR in the receiving device 3-1 described later. This is because when the broadcast wave is directly transmitted from the transmitting device 1-1 to the receiving device 3-1 described later, the symbol determination by the relay device 2-1 described later is not performed, so that a symbol error may occur. This is because it is not necessary to degenerate the LLR in the receiving device 3-1.

When the degeneration method is the addition method, the receiving device 3-1 described later can recognize that the degeneration processing off instruction has been received when the noise dispersion addition value σ ² _add = 0, and the noise dispersion addition value σ. ² When _add ≠ 0, it can be recognized that the instruction to perform the degeneration process has been received. Further, the receiving device 3-1 described later can recognize that the degeneration processing off instruction has been received when the noise dispersion clip value σ ² _clip = 0 when the degeneration method is the clip method, and the noise dispersion clip. When the value σ ² _clip ≠ 0, it can be recognized that the instruction to perform the degeneration process has been received.

The TxID generation unit 13 generates a preset identification signal of its own station (unique to the master station) as a TxID, and outputs the TxID to the multiplex information generation unit 14.

The multiplex information generation unit 14 inputs the degenerate amount information from the degenerate amount information generation unit 12, and also inputs the TxID from the TxID generation unit 13, and generates a bit sequence by multiplexing the degenerate amount information and the TxID. Then, the multiplex information generation unit 14 outputs the bit sequence as multiplex information to the modulation unit 15.

The modulation unit 15 inputs the multiplex information from the multiplex information generation unit 14, modulates the multiplex information, and outputs the modulated multiplex information to the synthesis unit 16 as a multiplex information signal. For example, the modulation unit 15 encodes the multiplex information with a highly correlated sequence such as a Gold signal, and applies BPSK modulation to the encoded multiplex information to attenuate it, thereby generating a multiplex information signal.

The synthesizing unit 16 inputs the main line signal from the modulation unit 11, inputs the multiplex information signal from the modulation unit 15, synthesizes the main line signal and the multiplex information signal by multiplexing, and combines the combined main line signal and the multiplex information signal. , Output to a transmitter (not shown). Then, the transmission unit (not shown) transmits a broadcast wave including the main line signal and the multiplex information signal (degenerate amount information and TxID of the transmission device 1-1) synthesized by the synthesis unit 16.

As a result, the main line signal, the degenerate amount information indicating the degeneration processing off, and the TxID of the degenerate device 1-1 are transmitted from the transmission device 1-1.

Further, the receiving device 3-1 described later can receive the degeneration amount information indicating the degeneration processing off from the transmitting device 1-1, so that the degenerate processing is not performed on the signal received from the transmitting device 1-1. can do.

In the transmission device 1-1, the multiplex information generation unit 14 multiplexes the degenerate amount information and the TxID, the synthesis unit 16 synthesizes the main line signal and the multiplex information signal, and the transmission unit (not shown) generates the main line signal and the multiplex information signal. Changed to transmit the broadcast wave including. On the other hand, the transmission device 1-1 does not have to transmit the TxID. In this case, the transmission device 1-1 does not include the TxID generation unit 13 and the multiplex information generation unit 14, and the modulation unit 15 inputs the reduction amount information from the reduction amount information generation unit 12 to perform modulation and modulation. The later shrinkage amount information is generated as a shrinkage amount information signal. Then, the synthesis unit 16 synthesizes the main line signal and the degenerate amount information signal, and the transmission unit (not shown) transmits a broadcast wave including the main line signal and the degenerate amount information signal.

[Relay station / Relay device 2 / Example 1]
Next, the relay device 2 provided in the relay station in the first embodiment will be described. FIG. 3 is a block diagram showing a configuration example of the relay device 2 of the first embodiment. The relay device 2-1 includes a transmission line equalization unit 20, a symbol determination unit 21, a remodulation unit 22, a relay station reception C / N estimation unit 23, a degenerate amount information generation unit 24, a TxID generation unit 25, and multiple information generation. It includes a unit 26, a modulation unit 27, and a synthesis unit 28.

The relay device 2-1 receives the broadcast wave transmitted from the transmission device 1-1. The transmission line equalization unit 20 inputs the received broadcast wave signal, performs transmission line equalization on the broadcast wave signal, and transmits the signal after the transmission line equalization to the relay station reception C / N estimation unit 23 and symbol determination. Output to unit 21.

The symbol determination unit 21 inputs the signal after the transmission line equalization from the transmission line equalization unit 20, performs symbol determination on the signal after the transmission line equalization, and outputs the signal after the symbol determination to the remodulation unit 22. .. The remodulation unit 22 inputs the signal after the symbol determination from the symbol determination unit 21, and remodulates the signal after the symbol determination.

Here, in the process from the transmission line equalization unit 20 to the remodulation unit 22, the multiplex information signal (reduction amount information and TxID) included in the broadcast wave signal transmitted from the transmission device 1-1 is removed and re-modulated. The modulated signal becomes the main line signal. The remodulation unit 22 outputs the remodulated signal as a main line signal to the synthesis unit 28.

The relay station reception C / N estimation unit 23 inputs the signal after the transmission line equalization from the transmission line equalization unit 20, and estimates the relay station reception C / N based on the signal after the transmission line equalization. Then, the relay station reception C / N estimation unit 23 outputs the relay station reception C / N to the degenerate amount information generation unit 24.

FIG. 4 is a flowchart showing a processing example of the degenerate amount information generation unit 24. The degenerate amount information generation unit 24 inputs the relay station reception C / N from the relay station reception C / N estimation unit 23 (step S401). Then, the degenerate amount information generation unit 24 uses a predetermined function to obtain degenerate amount information (noise dispersion addition value σ ² _add when the degenerate method is an addition method, and noise when the clip method is used) from the relay station reception C / N. The distributed clip value σ ² _clip ) is obtained (step S402).

Here, in the predetermined function, when the degeneration method is the addition method, the higher the relay station reception C / N, the lower the degree of degeneration of the LLR calculated by the receiving device 3-1 described later, so that the noise is reduced. A small value is output as the dispersion addition value σ ² _add , and a large value is output as the noise dispersion addition value σ ² _add in order to increase the degree of degeneracy of the LLR as the relay station reception C / N is lower. It is a function (having a negative correlation characteristic).

Further, when the degeneration method is the clip method, the predetermined function outputs a small value as the noise dispersion clip value σ ² _clip in order to reduce the degree of degeneration of the LLR as the relay station reception C / N is higher. However, the lower the relay station reception C / N is, the higher the degree of degeneracy of the LLR is, so that a large value is output as the noise dispersion clip value σ ² _clip (having a negative correlation characteristic).

The degenerate amount information generation unit 24 outputs the degenerate amount information to the multiplex information generation unit 26 (step S403).

The degenerate amount information generation unit 24 may use a preset table to read the degenerate amount information corresponding to the relay station reception C / N and output the degenerate amount information. The table stores the relay station reception C / N and the degenerate amount information corresponding to the relay station reception C / N, and has the same negative correlation characteristics as the above-mentioned predetermined function.

Further, the degenerate amount information generation unit 24 may generate a degenerate amount information having a uniform value in the entire band. Further, the degenerate amount information generation unit 24 may generate degenerate amount information for each segment. In this case, the relay station reception C / N estimation unit 23 estimates the relay station reception C / N for each segment, and the degenerate amount information generation unit 24 uses a predetermined function or a preset table for each segment. Then, the degenerate amount information is obtained from the relay station reception C / N. This processing for each segment is effective when multipath is included in the reception of the higher station.

Further, the degenerate amount information generation unit 24 may generate degenerate amount information for each predetermined number of segments in units of a predetermined number of segments, or may generate degenerate amount information for each carrier. good. In this case, the relay station reception C / N estimation unit 23 estimates the relay station reception C / N for each predetermined number of segments or carriers. Then, the degenerate amount information generation unit 24 obtains the degenerate amount information from the relay station reception C / N by using a predetermined function or a preset table for each of a predetermined number of segments or carriers.

FIG. 5 is a diagram showing an example of the relationship between the relay station reception C / N and the noise dispersion addition value σ ² _add (C / N conversion value). The horizontal axis shows the relay station reception C / N [dB], and the vertical axis shows the noise dispersion addition value σ ² _add (C / N conversion value) [dB].

As shown in FIG. 5, the relationship between the two is that the higher the relay station reception C / N, the larger the noise dispersion addition value σ ² _add (C / N conversion value), and the lower the relay station reception C / N. It has a characteristic (positive correlation characteristic) that the noise dispersion addition value σ ² _add (C / N conversion value) becomes smaller as it becomes.

That is, as the function used in the reduction amount information generation unit 24 (when the reduction method is the addition method), as described above, the higher the relay station reception C / N, the smaller the value as the noise dispersion addition value σ ² _add . Is output, and the lower the relay station reception C / N is, the larger the value is output as the noise dispersion addition value σ ² _add (having a negative correlation characteristic).

This is because when the relay station reception C / N is low, symbol errors are likely to occur, and by setting a large value as the noise dispersion addition value σ ² _add , the LLR is calculated when the area reception C / N is high. This is because the noise dispersion adjustment value σ ' ² used in the case can be set to a large value, and the LLR can be degenerated.

The same applies when the degenerate amount information generation unit 24 uses a preset table, and a table that reflects the characteristics of the above-mentioned function is used. Further, this function changes depending on the carrier modulation method, transmission parameters such as the coding rate, and the like. This is because, in the receiving device 3-1 described later, the appearance of an error when the area reception C / N is high changes depending on the transmission parameter or the like, and the noise dispersion addition value σ ² _add also changes.

FIG. 6 is a diagram showing an example of the relationship between the relay station reception C / N and the noise dispersion clip value σ ² _clip (C / N conversion value). The horizontal axis shows the relay station reception C / N [dB], and the vertical axis shows the noise dispersion clip value σ ² _clip (C / N conversion value) [dB].

As shown in FIG. 6, the relationship between the two is that the higher the relay station reception C / N, the larger the noise dispersion clip value σ ² _clip (C / N conversion value), and the lower the relay station reception C / N. The more it becomes, the smaller the noise dispersion clip value σ ² _clip (C / N conversion value) has (positive correlation characteristic).

That is, as the function used in the reduction amount information generation unit 24 (when the reduction method is the clip method), as described above, the higher the relay station reception C / N, the smaller the noise dispersion clip value σ ² _clip . Is output, and the lower the relay station reception C / N is, the larger the value is output as the noise dispersion clip value σ ² _clip (having a negative correlation characteristic).

This is because when the relay station reception C / N is low, symbol errors are likely to occur, and by setting a large value as the noise dispersion clip value σ ² _clip , the noise dispersion estimated value is set when the area reception C / N is high. This is because σ ² can be easily clipped, the noise dispersion adjustment value σ ' ² used when calculating the LLR can be made larger than that before clipping, and the LLR can be reduced.

The same applies when the degenerate amount information generation unit 24 uses a preset table, and a table that reflects the characteristics of the above-mentioned function is used. Further, this function changes depending on the transmission parameters such as the carrier modulation method and the coding rate, as in the case where the degeneration method is the addition method.

Returning to FIG. 3, the TxID generation unit 25 generates a preset identification signal of its own station (relay station-specific) as a TxID, and outputs the TxID to the multiplex information generation unit 26.

The multiplex information generation unit 26 inputs the degenerate amount information from the degenerate amount information generation unit 24, inputs the TxID from the TxID generation unit 25, and generates a bit sequence by multiplexing the degenerate amount information and the TxID. Then, the multiplex information generation unit 26 outputs the bit sequence as multiplex information to the modulation unit 27.

The modulation unit 27 inputs the multiplex information from the multiplex information generation unit 26, modulates the multiplex information, and outputs the modulated multiplex information to the synthesis unit 28 as a multiplex information signal. For example, the modulation unit 27 encodes the multiplex information in a highly correlated series such as a Gold signal, and applies BPSK modulation to the encoded multiplex information to attenuate it, similarly to the modulation unit 15 shown in FIG. , Generate multiplex information signals.

The synthesizing unit 28 inputs the main line signal from the remodulation unit 22 and inputs the multiplex information signal from the modulation unit 27, and synthesizes the main line signal and the multiplex information signal by multiplexing the main line signal and the multiplex information signal. Is output to a transmitter (not shown). Then, the transmission unit (not shown) transmits a broadcast wave including the main line signal and the multiplex information signal (degenerate amount information and TxID of the relay device 2-1) synthesized by the synthesis unit 28.

As a result, the main line signal, the degenerate amount information (noise dispersion addition value σ ² _add or noise dispersion clip value σ ² _clip ) and the TxID of the relay device 2-1 are transmitted from the relay device 2-1.

Further, the receiving device 3-1 described later can receive the degenerate amount information from the relay device 2-1 and can perform the degeneration process based on the degenerate amount information on the signal received from the relay device 2-1. can.

In the relay device 2-1 the multiplex information generation unit 26 multiplexes the contraction amount information and the TxID, the synthesis unit 28 synthesizes the main line signal and the multiplex information signal, and the transmission unit (not shown) generates the main line signal and the multiplex information signal. Changed to transmit the broadcast wave including. On the other hand, the relay device 2-1 does not have to transmit the TxID. In this case, the relay device 2-1 does not include the TxID generation unit 25 and the multiplex information generation unit 26, and the modulation unit 27 inputs the reduction amount information from the reduction amount information generation unit 24 to perform modulation and modulation. The later shrinkage amount information is generated as a shrinkage amount information signal. Then, the synthesis unit 28 synthesizes the main line signal and the degenerate amount information signal, and the transmission unit (not shown) transmits a broadcast wave including the main line signal and the degenerate amount information signal.

[Receiver / Receiver 3 / Example 1]
Next, the receiving device 3 provided in the general household in the first embodiment will be described. FIG. 7 is a block diagram showing a configuration example of the receiving device 3 of the first embodiment. The receiving device 3-1 includes a transmission line equalization unit 30, a multiplex information extraction unit 31, a demodulation unit 32, an LLR processing unit 33, and an LDPC decoding unit 34.

The receiving device 3-1 receives the broadcast wave transmitted from the transmitting device 1-1 and the relay device 2-1 respectively. The transmission line equalization unit 30 inputs the received broadcast wave signal, performs transmission line equalization on the broadcast wave signal, and outputs the signal after the transmission line equalization to the LLR processing unit 33.

The multiplex information extraction unit 31 inputs the received broadcast wave signal, extracts the multiplex information signal from the broadcast wave signal, and outputs the multiplex information signal to the demodulation unit 32. For example, the multiplex information extraction unit 31 sequentially correlates with the broadcast wave signal by using a highly correlated series such as the Gold signal used in the modulation units 15 and 27 shown in FIGS. 2 and 3. , Extracts the multiplex information signal that is multiplexed with the broadcast wave signal.

The demodulation unit 32 inputs a multiplex information signal from the multiplex information extraction unit 31, demodulates the multiplex information signal corresponding to the modulation units 15 and 27 shown in FIGS. 2 and 3, and is a signal after demodulation. The degenerate amount information and TxID are separated from the multiplex information. Then, the demodulation unit 32 outputs the TxID and outputs the degeneracy amount information to the LLR processing unit 33.

When the broadcast wave does not include TxID, the receiving device 3-1 includes a degenerate amount information extraction unit instead of the multiplex information extraction unit 31, and the degenerate amount information extraction unit uses the received broadcast wave signal. The degenerate amount information signal is extracted, and the demodulation unit 32 obtains the degenerate amount information by demolishing the degenerate amount information signal.

The LLR processing unit 33 inputs the signal after the transmission line equalization from the transmission line equalization unit 30, and also inputs the reduction amount information from the demodulation unit 32, and the noise dispersion estimated value is based on the signal after the transmission line equalization. Estimate σ ² . Then, the LLR processing unit 33 adjusts the noise dispersion estimated value σ ² based on the degeneracy amount information, and obtains the noise dispersion adjustment value σ ' ² . Then, the LLR processing unit 33 calculates the LLR based on the signal after the transmission line equalization and the noise dispersion adjustment value σ ' ² , and outputs the LLR to the LDPC decoding unit 34.

Here, when the degenerate amount information is the information transmitted from the transmission device 1-1, the degenerate amount information is information indicating that the degenerate processing is off (when the degenerate method is the addition method, the noise dispersion addition value σ ² _add = 0, in the case of the clip method, the noise dispersion clip value σ ² _clip = 0). In this case, the degeneration process is not performed in the LLR processing unit 33. On the other hand, when the shrinkage amount information is the information transmitted from the relay device 2-1 the shrinkage amount information is the noise dispersion addition value σ ² _add ≠ 0 in the case of the addition method, and the noise dispersion clip value in the case of the clip method. σ ² _clip ≠ 0. In this case, the degeneration process is performed in the LLR processing unit 33. The details of the LLR processing unit 33 will be described later.

The LDPC decoding unit 34 inputs the LLR from the LLR processing unit 33, performs LDPC decoding on the LLR, restores the original broadcast signal, and outputs the LLR.

(LLR processing unit 33)
Next, the LLR processing unit 33 shown in FIG. 7 will be described in detail. FIG. 8 is a block diagram showing a configuration example of the LLR processing unit 33, and FIG. 9 is a flowchart showing a processing example of the LLR processing unit 33. The LLR processing unit 33 includes a noise dispersion estimation unit 40, a noise dispersion adjustment unit 41, and an LLR calculation unit 42.

The LLR processing unit 33 inputs the signals x _I and x _Q after the transmission line equalization from the transmission line equalization unit 30, and the decompression amount information (noise dispersion addition value σ ² _add or noise dispersion clip value) from the demodulation unit 32. σ ² _clip ) is input (step S901). x _I is the I-axis component of the received symbol and x _Q is the Q-axis component of the received symbol.

The noise dispersion estimation unit 40 inputs the signals x _I and x _Q after the transmission line equalization, and obtains the noise dispersion estimation value σ ² based on the signals x _I and x _Q after the transmission line equalization (step S902). ). Then, the noise dispersion estimation unit 40 outputs the noise dispersion estimation value σ ² to the noise dispersion adjustment unit 41.

The noise dispersion adjusting unit 41 inputs the noise dispersion estimated value σ ² from the noise dispersion estimation unit 40 and also inputs the decay amount information, and the noise dispersion adjustment value σ'based on the noise dispersion estimated value σ ² and the decay amount information. ² is obtained (step S903). Then, the noise dispersion adjustment unit 41 outputs the noise dispersion adjustment value σ ' ² to the LLR calculation unit 42. The details of the noise dispersion adjusting unit 41 will be described later.

The LLR calculation unit 42 inputs the signals x _I and x _Q after equalization of the transmission path, and also inputs the noise dispersion adjustment value σ ' ² from the noise dispersion adjustment unit 41. Then, the LLR calculation unit 42 obtains λ _k (LLR) based on the signals x _I , x _Q and the noise dispersion adjustment value σ ' ² after the transmission line equalization using the following equations (step S904). The LLR calculation unit 42 outputs λ _k to the LDPC decoding unit 34 (step S905).

The above equation (1) is λ from the Euclidean distance between the receiving point, which is the signal x _I , x _Q after the equalization of the transmission path, and the specified point of the constellation, and the noise dispersion (noise dispersion adjustment value σ ' ² ). It is an expression to calculate _k .

λ _k is the log-likelihood ratio of the k-th bit when the carrier modulation multi-valued number is M = 2 ^V. The carrier modulation multi-valued number is M = 2 ^V , the specified signal point arrangement is sm (0 ≤ _m <2 ^V ), the I and Q coordinates are sm _{, I} , sm _{, Q} , and the real part of the received symbol is x. Let _I , the imaginary part be x _Q , and the noise dispersion adjustment value be σ ' ² . _{Sk, 0} , Sk, 1 are a set of signal points in which the kth bit represents 0 _{, 1} , respectively.

(Noise dispersion adjustment unit 41)
Next, the processing of the noise dispersion adjusting unit 41 shown in FIG. 8 and the process of step S903 shown in FIG. 9 will be described in detail.

(When the degeneracy method is the addition method)
FIG. 10 is a diagram illustrating processing (in the case of the addition method) of the first configuration example of the noise dispersion adjusting unit 41. The noise variance adjusting unit 41-1 to which the addition method is applied adds the noise variance addition value σ ² _add of the degenerate amount information to the noise variance estimated value σ ² by using the following equation, and the noise variance adjustment value σ ' ² Ask for.

FIG. 11 is a diagram showing a noise dispersion adjustment value σ ' ² (in the case of the addition method) obtained by the first configuration example of the noise dispersion adjustment unit 41. In FIG. 11, the horizontal axis represents the area reception C / N [dB], and the vertical axis represents the noise dispersion adjustment value σ ' ² .

From FIG. 11, the correspondence between the area reception C / N and the noise dispersion adjustment value σ ' ² is that the higher the area reception C / N, the smaller the noise dispersion adjustment value σ ' ² , and the area reception C / N becomes. It can be seen that the lower the value, the larger the noise dispersion adjustment value σ ' ² (negative correlation characteristic).

This negative correlation characteristic has the greatest degree when there is no noise addition (no adjustment), that is, when the noise variance addition value σ ² _add = 0 of the degenerate amount information. That is, the degree of this negative correlation characteristic becomes larger as the noise dispersion addition value σ ² _add becomes smaller, and the degree becomes smaller as the noise dispersion addition value σ ² _add becomes larger.

When there is no noise addition (no adjustment), that is, when the degeneration processing is off, the noise dispersion addition value σ ² _add = 0, and when the area reception C / N is high, the noise dispersion adjustment value σ ' ² becomes small and the initial LLR. Is a high value.

On the other hand, when the noise dispersion addition value σ ² _add ≠ 0, the noise dispersion is adjusted by the noise dispersion adjustment unit 41-1 shown in FIG. 10, so that when the area reception C / N is high, the noise dispersion is not added. Therefore, the noise dispersion adjustment value σ ' ² becomes large, and the initial LLR can be reduced.

As a result, the initial LLR of all the bits of the received signal is degenerated, so that the bit erroneously determined by the relay device 2-1 can be corrected in the LDPC decoding unit 34 in the subsequent stage.

(When the degeneration method is the clip method)
FIG. 12 is a diagram illustrating processing (in the case of the clip method) of the second configuration example of the noise dispersion adjusting unit 41, and FIG. 13 is a noise dispersion estimated value input by the second configuration example of the noise dispersion adjusting unit 41. It is a figure which shows the relationship between σ 2 and the noise dispersion adjustment value σ ' ² (in the case of a clip method) to be output. In FIG. 13, the horizontal axis indicates the noise dispersion estimated value σ ² , and the vertical axis indicates the noise dispersion adjustment value σ ' ² .

As shown in FIG. 13, the noise variance adjusting unit 41-2 to which the clip method is applied uses the following equation when the noise variance estimated value σ ² is equal to or more than the noise variance clip value σ ² _clip of the degenerate amount information. The noise variance estimated value σ ² is set to the noise variance adjustment value σ ' ² as it is. On the other hand, when the noise dispersion estimated value σ ² is less than the noise dispersion clip value σ ² _clip , the noise dispersion adjusting unit 41-2 applies clipping processing to the noise dispersion estimated value σ ² and makes the noise dispersion clip value σ ² _clip noise. Set the variance adjustment value σ ' ² .

FIG. 14 is a diagram showing a noise dispersion adjustment value σ ' ² (in the case of the clip method) obtained by the second configuration example of the noise dispersion adjustment unit 41. In FIG. 14, the horizontal axis represents the area reception C / N [dB], and the vertical axis represents the noise dispersion adjustment value σ ' ² .

From FIG. 14, the correspondence between the area reception C / N and the noise dispersion adjustment value σ ' ² is that the higher the area reception C / N, the smaller the noise dispersion adjustment value ^σ'2 and the area reception C / N. It can be seen that the lower the value, the larger the noise dispersion adjustment value σ ' ² (negative correlation characteristic).

This negative correlation characteristic is that when there is no noise addition (no adjustment), that is, when the degeneration processing is off, the noise dispersion clip value σ ² _clip = 0, and in the entire range of the area reception C / N where the clip processing is not performed. It is appearing.

In addition, this negative correlation characteristic appears in the range where the area reception C / N that is not clipped based on the clip position is low when the noise dispersion clip value σ ² _clip = 1.00 × 10 ^-3 . There is. Further, in the high range of the area reception C / N in which the clip processing is performed with reference to the clip position, the noise dispersion adjustment value σ ' ² is a constant value.

When there is no noise addition (no adjustment), that is, when the noise dispersion clip value σ ² _clip = 0, when the area reception C / N is high, the noise dispersion adjustment value σ ' ² becomes small and the initial LLR becomes a high value. Become.

On the other hand, when the noise dispersion clip value σ ² _clip ≠ 0, the noise dispersion is adjusted by the noise dispersion adjustment unit 41-2 shown in FIG. 12, so that when the area reception C / N is high, the noise dispersion is not added. Therefore, the noise dispersion adjustment value σ ' ² becomes large (the noise dispersion adjustment value σ ' ² becomes a constant value), and the initial LLR can be reduced.

That is, by appropriately generating the noise dispersion clip value σ ² _clip , the initial LLR is not degenerated near the required C / N in the area reception C / N, and the area reception C / N in which an error can occur is high. Then, the initial LLR can be degenerated. As a result, the initial LLR of all the bits of the received signal is degenerated, so that the LDPC decoding unit 34 can correct the bits erroneously determined by the relay device 2-1.

As described above, according to the transmission device 1-1 of the first embodiment, the degeneration amount information generation unit 12 has a preset degeneration amount information indicating that the degeneration process is off (when the degeneration method is an addition method, noise dispersion addition is performed). The value σ ² _add = 0, and in the case of the clip method, the noise dispersion clip value σ ² _clip = 0) is generated as the degeneracy amount information of the master station.

The multiplex information generation unit 14 multiplexes the degenerate amount information and the TxID of the own station to generate the multiplex information, and the modulation unit 15 modulates the multiplex information to generate the multiplex information signal.

The synthesis unit 16 synthesizes by multiplexing the main line signal and the multiplex information signal generated by the LDPC coding unit 10 and the modulation unit 11, and the transmission unit (not shown) is the main line signal and the multiplex information synthesized by the synthesis unit 16. A broadcast wave including a signal (degenerate amount information and TxID of the transmission device 1-1) is transmitted.

Further, according to the relay device 2-1 of the first embodiment, when the broadcast wave is received from the transmission device 1-1, the relay station reception C / N estimation unit 23 is the signal equalized by the transmission line equalization unit 20. The relay station reception C / N is estimated based on. The degenerate amount information generation unit 24 uses a predetermined function to generate degenerate amount information from the relay station reception C / N (noise dispersion addition value σ ² _add when the degeneration method is an addition method, noise dispersion clip when the degeneration method is a clip method). Find the value σ ² _clip ).

As a result, the higher the relay station reception C / N, that is, when the symbol error is less likely to occur, a smaller noise dispersion addition value σ ² _add or noise dispersion clip value σ ² _clip is obtained. On the other hand, when the relay station reception C / N is lower, that is, when a symbol error is likely to occur, a large noise dispersion addition value σ ² _add or noise dispersion clip value σ ² _clip is obtained.

The multiplex information generation unit 26 multiplexes the degenerate amount information and the TxID of the own station to generate the multiplex information, and the modulation unit 27 modulates the multiplex information to generate the multiplex information signal.

The synthesizing unit 28 synthesizes by multiplexing the main line signal and the multiplex information signal generated by the symbol determination unit 21 and the remodulation unit 22. Then, the relay device 2-1 transmits a broadcast wave including a main line signal and a multiplex information signal (degenerate amount information and TxID of the relay device 2-1).

Further, according to the receiving device 3-1 of the first embodiment, the multiplex information extraction unit 31 extracts the multiplex information signal from the received broadcast wave signal, and the demodulation unit 32 demodulates the multiplex information signal and demodulates it. The demodulation amount information and the TxID are separated from the multiplex information which is the later signal.

The LLR processing unit 33 estimates the noise variance estimated value σ ² from the signal equalized by the transmission line equalization unit 30, adjusts the noise variance estimated value σ ² based on the contraction amount information, and adjusts the noise variance adjusted value σ. ' ² is obtained, and LLR is calculated based on the signal and noise dispersion adjustment value σ ' ² after channel equalization.

Here, when the degeneration method is the addition method, the LLR processing unit 33 adds the noise variance addition value σ ² _add of the degeneration amount information to the noise variance estimated value σ ² to obtain the noise variance adjustment value σ ' ² . On the other hand, when the reduction method is the clip method, the LLR processing unit 33 uses the noise dispersion estimation value σ ² as it is as the noise dispersion adjustment value when the noise dispersion estimation value σ ² is the noise dispersion clip value σ ² _clip or more of the reduction amount information. If σ ' ² is set and the noise dispersion estimate σ ² is less than the noise variance clip value σ ² _clip , the noise variance estimate σ ² is clipped and the noise variance clip value σ ² _clip is set to the noise variance adjustment value σ. 'Set to ²

The LDPC decoding unit 34 performs LDPC decoding on the LLR, restores the original broadcast signal, and outputs the original broadcast signal.

Thereby, under the situation where the relay station reception C / N is low and the area reception C / N is high, the noise dispersion adjustment value σ ' ² can be set to a large value, and the LLR can be degenerated. Conventionally, the relay station reception C / N cannot be reflected in the LLR in the receiving device 3, and when a symbol error occurs because the relay station reception C / N is low, when the area reception C / N is high, The error could not be corrected in the receiving device 3.

In the embodiment of the present invention, the relay station reception C / N is reflected in the LLR in the receiving device 3, and the LLR is degenerated, so that the absolute value of the LLR becomes small and the probability of the bit value 0 or 1 becomes low. When the LDPC decoding process is performed using the LLR in such an ambiguous state, the symbol error may be overturned and the error may be corrected.

Therefore, it is possible to suppress an error in the retransmitted signal received by the receiving device 3-1 under a high area reception C / N situation without adding noise to the signal by the relay device 2-1.

[Example 2]
Next, Example 2 will be described. As described above, in the second embodiment, the transmitting device generates and transmits a corresponding table including the degenerate amount information for each of the transmitting device and the relay device, and the receiving device receives the TxID of the transmission source of the received signal from the corresponding table. This is an example in which the degenerate amount information corresponding to is read out and the LLR is degenerated based on the degenerate amount information.

[Master Station / Transmitter 1 / Example 2]
First, the transmission device 1 provided in the master station in the second embodiment will be described. FIG. 15 is a block diagram showing a configuration example of the transmission device 1 of the second embodiment. The transmission device 1-2 includes an LDPC coding unit 10, a modulation unit 11, 15, a TxID generation unit 13, a synthesis unit 16, and a corresponding table generation unit 17.

Since the LDPC coding unit 10, the modulation unit 11 and the TxID generation unit 13 are the same as the LDPC coding unit 10, the modulation unit 11 and the TxID generation unit 13 shown in FIG. 2, description thereof will be omitted here.

The modulation unit 15 inputs TxID from the TxID generation unit 13, modulates the TxID, and outputs the modulated TxID to the synthesis unit 16. For example, the modulation unit 15 encodes the TxID with a highly correlated sequence such as a Gold signal, and applies BPSK modulation to the encoded TxID to attenuate it, thereby generating the modulated TxID.

A receiving unit (not shown) provided in the transmitting device 1-2 receives the relay station reception C / N and TxID of the relay device 2-2 transmitted via a dedicated line or the like from the relay device 2-2 described later. Then, the receiving unit outputs the relay station reception C / N and TxID of the relay device 2-2 to the corresponding table generation unit 17.

FIG. 16 is a flowchart showing a processing example of the corresponding table generation unit 17. The correspondence table generation unit 17 inputs the relay station reception C / N and TxID of the relay device 2-2 from a reception unit (not shown) (step S1601).

Similar to the processing of the degeneration amount information generation unit 12 shown in FIG. 2, the corresponding table generation unit 17 has a preset degeneration amount information (noise dispersion addition value σ ² _add = 0 or noise dispersion clip) indicating that the degeneration processing is off. The value σ ² _clip = 0) is generated as the degeneracy amount information of the master station.

The corresponding table generation unit 17 uses a predetermined function in the same manner as the processing of the degeneration amount information generation unit 24 shown in FIGS. 3 and 4, and degenerate amount information (noise dispersion addition value σ) from the relay station reception C / N. ² _add or noise dispersion clip value σ ² _clip ) is obtained (step S1602).

The corresponding table generation unit 17 has preset TxID of its own station (unique to the master station, transmission device 1-2) and degeneration amount information of the master station, and TxID of the relay device 2-2 and degeneration generated in step S1602. A correspondence table is generated from the quantity information (step S1603). Then, the corresponding table generation unit 17 outputs the corresponding table to a broadcast signal generation unit (not shown) (step S1604).

FIG. 17 is a diagram showing an example of a corresponding table (in the case of an addition method). The correspondence table in the case of the addition method is composed of the noise variance addition value σ ² _add of TxID and degeneracy amount information.

In the correspondence table of FIG. 17, the TxID of the transmission device 1-2 which is the master station and the noise dispersion addition value σ ² _add = 0 indicating the reduction processing off corresponding to the TxID are received from the first relay device 2-2. The TxID of the relay device 2-2 and the noise dispersion addition value obtained in step S1602 corresponding to the TxID σ ² _add = 1.0 × 10 ^-3 , and the relay received from the second relay device 2-2. The TxID of the device 2-2 and the noise dispersion addition value σ ² _add = 2.5 × 10 ^-3 obtained in step S1602 corresponding to the TxID are stored.

The TxID and noise dispersion addition value σ ² _add for each relay device 2-2 (for each relay station) are the relay device 2-2 which is the transmission source of the relay station reception C / N and TxID received by the transmission device 1-2. It is data for each.

FIG. 18 is a diagram showing an example of a corresponding table (in the case of the clip method). The corresponding table in the case of the clip method is composed of the noise dispersion clip value σ ² _clip of the TxID and the degeneracy amount information.

In the correspondence table of FIG. 18, the TxID of the transmission device 1-2 which is the master station and the noise dispersion clip value σ ² _clip = 0 indicating the reduction processing off corresponding to the TxID are received from the first relay device 2-2. The TxID of the relay device 2-2 and the noise dispersion clip value σ ² _clip = 2.0 × 10 ^-3 obtained in step S1602 corresponding to the TxID, and the relay received from the second relay device 2-2. The TxID of the device 2-2 and the noise dispersion clip value σ ² _clip = 8.0 × 10 ^-3 obtained in step S1602 corresponding to the TxID are stored.

The TxID and noise distribution clip value σ ² _clip for each relay device 2-2 (for each relay station) are the relay device 2-2 which is the transmission source of the relay station reception C / N and TxID received by the transmission device 1-2. It is data for each.

As in the case of the first embodiment, the corresponding table generation unit 17 reads out the degenerate amount information corresponding to the relay station reception C / N by using a preset table instead of the predetermined function. The degeneracy amount information may be requested.

Further, the corresponding table generation unit 17 may generate the degeneration amount information of a uniform value in the entire band as in the degeneration amount information generation unit 24 shown in FIG. 3, and may generate the degeneration amount information for each segment. It may be generated. Further, the corresponding table generation unit 17 may generate the degeneracy amount information for each predetermined number of segments, or may generate the degeneracy amount information for each carrier.

Returning to FIG. 15, the broadcast signal generation unit (not shown) inputs a corresponding table from the corresponding table generation unit 17, stores the corresponding table in the broadcast signal, generates a broadcast signal including the corresponding table, and outputs the broadcast signal to LDPC. It is output to the coding unit 10. For example, the broadcast signal generation unit stores the correspondence table in the ES (Engineering Service) used for software update by broadcast waves, the fixed reception and partial reception data broadcasting area, or the LLch. Generate a broadcast signal that includes.

The broadcast signal including the corresponding table is LDPC-encoded by the LDPC coding unit 10 and modulated by the modulation unit 11, so that the main line signal including the corresponding table is generated.

The synthesizing unit 16 inputs the main line signal including the corresponding table from the modulation unit 11, inputs the modulated TxID from the modulation unit 15, and combines the main line signal and the modulated TxID by multiplexing. Then, the transmission unit (not shown) transmits a broadcast wave including the main line signal synthesized by the synthesis unit 16 and the TxID of the transmission device 1-2.

As a result, the main line signal including the corresponding table and the TxID of the transmission device 1-2 are transmitted from the transmission device 1-2. As shown in FIGS. 17 and 18, the corresponding table was obtained by using the TxID of the transmission device 1-2, the degeneration amount information indicating the degeneration processing off, the TxID of each relay device 2-2, and a predetermined function. It consists of degenerate amount information.

Further, the receiving device 3-2, which will be described later, can receive the TxID and the corresponding table of the transmitting device 1-2 from the transmitting device 1-2. The receiving device 3-2 can determine from the received TxID that the received signal is a signal transmitted from the transmitting device 1-2. Further, the receiving device 3-2 can read the degenerate amount information corresponding to the received TxID using the received correspondence table and perform the degeneration process based on the degenerate amount information.

[Relay station / Relay device 2 / Example 2]
Next, the relay device 2 provided in the relay station in the second embodiment will be described. FIG. 19 is a block diagram showing a configuration example of the relay device 2 of the second embodiment. The relay device 2-2 includes a transmission line equalization unit 20, a symbol determination unit 21, a remodulation unit 22, a relay station reception C / N estimation unit 23, a TxID generation unit 25, a modulation unit 27, and a synthesis unit 28. There is.

The relay device 2-2 receives the broadcast wave transmitted from the transmission device 1-2. Since the transmission line equalization unit 20, the symbol determination unit 21, and the remodulation unit 22 are the same as the transmission line equalization unit 20, the symbol determination unit 21, and the remodulation unit 22 shown in FIG. 3, description thereof is omitted here. do.

Here, in the process from the transmission line equalization unit 20 to the remodulation unit 22, the TxID of the transmission device 1-2 included in the broadcast wave signal transmitted from the transmission device 1-2 is removed, and after remodulation. Signal becomes the main line signal. The remodulation unit 22 outputs the remodulated signal as a main line signal (including a corresponding table) to the synthesis unit 28.

The relay station reception C / N estimation unit 23 estimates the relay station reception C / N based on the signal after the transmission line is equalized, similar to the processing of the relay station reception C / N estimation unit 23 shown in FIG. .. Then, the relay station reception C / N estimation unit 23 outputs the relay station reception C / N to a transmission unit (not shown).

Similar to the processing of the TxID generation unit 25 shown in FIG. 3, the TxID generation unit 25 generates a preset identification signal of its own station (relay station specific) as a TxID. Then, the TxID generation unit 25 outputs the TxID to a transmission unit (not shown) and outputs the TxID to the modulation unit 27.

The transmission unit (not shown) inputs the relay station reception C / N from the relay station reception C / N estimation unit 23 and the TxID from the TxID generation unit 25, and inputs the relay station reception C / N of the relay device 2-2. And as TxID, it is transmitted to the transmission device 1-2 via a dedicated line or the like. As a result, the relay station reception C / N and TxID of the relay device 2-2 are fed back to the transmission device 1-2.

The modulation unit 27 inputs TxID from the TxID generation unit 25, modulates the TxID, and outputs the modulated TxID to the synthesis unit 28. For example, the modulation unit 27 encodes the TxID with a highly correlated sequence such as a Gold signal, and applies BPSK modulation to the encoded TxID to attenuate it, thereby generating the modulated TxID.

The synthesizing unit 28 inputs the main line signal from the remodulation unit 22 and inputs the modulated TxID from the modulation unit 27, and combines the main line signal and the modulated TxID by multiplexing the main line signal and the modulated TxID. Then, the transmission unit (not shown) transmits a broadcast wave including the main line signal synthesized by the synthesis unit 28 and the TxID of the relay device 2-2.

As a result, the relay station reception C / N and TxID of the relay device 2-2 are transmitted from the relay device 2-2 to the transmission device 1-2, and the main line signal including the corresponding table and the TxID of the relay device 2-2 are transmitted. Is transmitted to the receiving device 3-2.

Further, the transmission device 1-2 can receive the relay station reception C / N and TxID of the relay device 2-2 from the relay device 2-2, and the relay device 1-2 is based on the relay station reception C / N. 2-2 degeneracy amount information can be generated.

Further, the receiving device 3-2, which will be described later, can receive the TxID of the relay device 2-2 from the relay device 2-2, and the received signal is transmitted from the relay device 2-2 from the received TxID. It can be determined that it is a signal. Then, the receiving device 3-2 reads the degenerate amount information corresponding to the received TxID using the corresponding table received from the transmitting device 1-2 or the relay device 2-2, and the degenerate process based on the degenerate amount information. It can be performed.

[Receiver / Receiver 3 / Example 2]
Next, the receiving device 3 provided in the general household in the third embodiment will be described. FIG. 20 is a block diagram showing a configuration example of the receiving device 3 of the second embodiment. The receiving device 3-2 includes a transmission line equalization unit 30, an LLR processing unit 33, an LDPC decoding unit 34, a TxID extraction unit 35, and a degenerate amount information reading unit 36.

The receiving device 3-2 receives the broadcast wave transmitted from the transmitting device 1-2 and the relay device 2-2. Since the transmission line equalization unit 30, the LLR processing unit 33 and the LDPC decoding unit 34 are the same as the transmission line equalization unit 30, the LLR processing unit 33 and the LDPC decoding unit 34 shown in FIG. 7, the description thereof is omitted here. do.

Here, the LDPC decoding unit 34 extracts the corresponding table from the broadcast signal restored by the LDPC decoding process, and outputs the corresponding table to the degenerate amount information reading unit 36. For example, when the corresponding table is included in the ES, fixed reception and partial reception data broadcasting area of the broadcast signal, or LLch, the LDPC decoding unit 34 may use the ES, fixed reception and partial reception data broadcasting area of the broadcast signal. Or extract the corresponding table from LLch.

The TxID extraction unit 35 inputs the received broadcast wave signal, extracts the TxID of the transmission device 1-2 or the relay device 2-2 that has transmitted the signal from the broadcast wave signal, and degenerates the TxID. Output to the reading unit 36. For example, the TxID extraction unit 35 sequentially correlates with the broadcast wave signal by using a highly correlated series such as the Gold signal used in the modulation units 15 and 27 shown in FIGS. 15 and 19. Extract the TxID multiplexed with the broadcast wave signal.

FIG. 21 is a flowchart showing a processing example of the degenerate amount information reading unit 36. The degenerate amount information reading unit 36 inputs the corresponding table from the LDPC decoding unit 34 and inputs the TxID from the TxID extraction unit 35 (step S2101).

The degenerate amount information reading unit 36 reads the degenerate amount information corresponding to the TxID from the corresponding table (step S2102), and outputs the degenerate amount information to the LLR processing unit 33 (step S2103).

For example, when the degeneration method is an addition method and the TxID of the transmission device 1-2 is extracted by the TxID extraction unit 35, the degeneration amount information reading unit 36 uses the corresponding table shown in FIG. 17 to display the transmission device 1-2. Read the noise variance addition value σ ² _add = 0 of the degenerate amount information corresponding to TxID. Then, the degenerate amount information reading unit 36 outputs the noise dispersion addition value σ ² _add = 0 of the degenerate amount information to the LLR processing unit 33. In this case, since the noise dispersion addition value σ ² _add = 0 indicates that the degeneration processing is off, the degeneration processing is not performed in the LLR processing unit 33.

Further, the degenerate method is an addition method, and when the TxID of the relay device 2-2 is extracted by the TxID extraction unit 35, the degenerate amount information reading unit 36 uses the corresponding table shown in FIG. 17 to display the relay device 2-2. Read the noise variance addition value σ ² _add of the degenerate amount information corresponding to the TxID of. Then, the degenerate amount information reading unit 36 outputs the noise dispersion addition value σ ² _add of the degenerate amount information to the LLR processing unit 33. In this case, the degeneration process is performed in the LLR processing unit 33.

For example, when the degeneration method is the clip method and the TxID of the transmission device 1-2 is extracted by the TxID extraction unit 35, the degeneration amount information reading unit 36 of the transmission device 1-2 is based on the corresponding table shown in FIG. Read the noise dispersion clip value σ ² _clip = 0 of the degeneracy amount information corresponding to TxID. Then, the degenerate amount information reading unit 36 outputs the noise dispersion clip value σ ² _clip = 0 of the degenerate amount information to the LLR processing unit 33. In this case, since the noise dispersion clip value σ ² _clip = 0 indicates that the degeneration processing is off, the degeneration processing is not performed in the LLR processing unit 33.

Further, when the degeneration method is a clip method and the TxID of the relay device 2-2 is extracted by the TxID extraction unit 35, the degeneration amount information reading unit 36 uses the corresponding table shown in FIG. 18 to display the relay device 2-2. Read the noise dispersion clip value σ ² _clip of the degeneracy amount information corresponding to the TxID of. Then, the degenerate amount information reading unit 36 outputs the noise dispersion clip value σ ² _clip of the degenerate amount information to the LLR processing unit 33. In this case, the degeneration process is performed in the LLR processing unit 33.

As a result, the degenerate processing is performed by the LLR processing unit 33, so that the initial LLR of all the bits of the received signal is degenerated, and the LDPC decoding unit 34 corrects the bits erroneously determined by the relay device 2-2. be able to.

As described above, according to the transmission device 1-2 of the second embodiment, the corresponding table generation unit 17 uses the relay station reception C / N and TxID of the relay device 2-2 transmitted from the relay device 2-2. Input and obtain degenerate amount information (noise dispersion addition value σ ² _add or noise dispersion clip value σ ² _clip ) from the relay station reception C / N using a predetermined function.

As a result, the higher the relay station reception C / N, that is, when the symbol error is less likely to occur, a smaller noise dispersion addition value σ ² _add or noise dispersion clip value σ ² _clip is obtained. On the other hand, when the relay station reception C / N is lower, that is, when a symbol error is likely to occur, a large noise dispersion addition value σ ² _add or noise dispersion clip value σ ² _clip is obtained.

The correspondence table generation unit 17 includes the TxID of the transmission device 1-2, preset degeneracy amount information (noise dispersion addition value σ ² _add = 0 or noise dispersion clip value σ ² _clip = 0), and a relay device. A correspondence table consisting of TxID for each 2-2 and degeneracy amount information obtained by using a predetermined function is generated. A broadcast signal generation unit (not shown) generates a broadcast signal including a corresponding table.

The synthesizing unit 16 synthesizes by multiplexing the main line signal generated from the broadcast signal by the LDPC coding unit 10 and the modulation unit 11 and the TxID modulated by the modulation unit 15. Then, the transmission unit (not shown) transmits a broadcast wave including the main line signal (including the corresponding table) synthesized by the synthesis unit 16 and the TxID of the transmission device 1-2.

Further, according to the relay device 2-2 of the second embodiment, when the broadcast wave is received from the transmission device 1-2, the relay station reception C / N estimation unit 23 is the signal equalized by the transmission line equalization unit 20. The relay station reception C / N is estimated based on. Then, the relay station reception C / N and TxID of the relay device 2-2 are transmitted to the transmission device 1-2.

The synthesizing unit 28 synthesizes by multiplexing the main line signal generated by the symbol determination unit 21 and the remodulation unit 22 and the TxID modulated by the modulation unit 27. Then, the relay device 2-2 transmits a broadcast wave including the main line signal and the TxID of the relay device 2-2.

Further, according to the receiving device 3-2 of the second embodiment, the TxID extraction unit 35 extracts the TxID of the transmitting device 1-2 or the relay device 2-2 that has transmitted the signal from the received broadcast wave signal. do. The degenerate amount information reading unit 36 reads the degenerate amount information corresponding to the TxID from the corresponding table decoded and extracted by the LDPC decoding unit 34.

The LLR processing unit 33 estimates the noise variance estimated value σ ² from the signal equalized by the transmission line equalization unit 30, adjusts the noise variance estimated value σ ² based on the contraction amount information, and adjusts the noise variance adjusted value σ. ' ² is obtained, and LLR is calculated based on the signal and noise dispersion adjustment value σ ' ² after channel equalization. The LDPC decoding unit 34 performs LDPC decoding on the LLR, restores the original broadcast signal, and outputs the original broadcast signal.

As a result, the noise dispersion adjustment value σ ' ² can be set to a large value under the situation where the relay station reception C / N is low and the area reception C / N is high, as in the case of the first embodiment. Can be degenerated. Therefore, it is possible to suppress an error in the retransmitted signal received by the receiving device 3-2 under a high area reception C / N condition without adding noise to the signal by the relay device 2-2.

〔simulation result〕
Next, the simulation results for verifying the degenerate effect of LLR will be described. FIG. 22 is a diagram showing a simulation system. This simulation system is composed of a system assuming a transmission device 1 provided in a master station, a relay device 2 provided in a relay station, and a receiving device 3 provided in a general household. The following processing of the transmitting device 1, the relay device 2, and the receiving device 3 is performed as a simulation by a computer.

The transmitter 1 includes PN (pseudo-random) generation, LDPC coding, BIL (bit interleaving), carrier modulation, frequency IL (interleaving), SP (scattered pilot) insertion, IFFT (inverse fast Fourier transform) and GI (inverse fast Fourier transform). (Guard interval) is added, and the broadcast wave is transmitted. It is assumed that the broadcast wave from the transmission device 1 is transmitted to the relay device 2 and noise is generated in the transmission line between the transmission device 1 and the relay device 2. The C / N ratio affected by this noise is estimated as the relay station reception C / N.

The relay device 2 receives the broadcast wave transmitted from the transmission device 1, GI removal, FFT (fast Fourier transform), equalization, symbol determination (no determination, hard determination or soft determination), SP insertion, GI assignment, and so on. The Fourier process is performed and the broadcast wave is retransmitted. It is assumed that the broadcast wave from the relay device 2 is retransmitted to the receiving device 3 and noise is generated in the transmission line between the relay device 2 and the receiving device 3. The C / N ratio affected by this noise is the area reception C / N.

The receiving device 3 receives the broadcast wave retransmitted from the relay device 2, GI removal, FFT, equalization, frequency DeIL (deinterleave), Euclidean distance calculation between the receiving point and the signal point, noise dispersion estimation, and noise dispersion. It performs adjustment, initial LLR calculation, LDPC decoding, DeBIL (bit deinterleave) and BER (bit error rate) measurement processing.

(Simulation result in case of addition method)
First, the simulation result when the degeneracy method is the addition method will be described. FIG. 23 is a diagram showing simulation specifications (in the case of the addition method). In the simulation specifications of the addition method, the hierarchy, modulation, coding rate, SP arrangement, and relay conditions are as shown in FIG.

FIG. 24 is a diagram showing BER characteristics (in the case of the addition method) obtained by simulation. The horizontal axis represents area reception C / N [dB], and the vertical axis represents BER. The dotted line shows the characteristics when AWGN (without relay), that is, the receiving device 3 directly receives the broadcast wave from the transmitting device 1, and the solid line with * shows the characteristics when the symbol determination is not performed. The solid line with + indicates the characteristics when the hardness judgment and the noise dispersion adjustment are not performed (degeneration processing is off), and the solid line with ■ indicates the characteristics when the soft judgment and the noise dispersion adjustment are not performed. The dotted line with Δ indicates the characteristics when the softness judgment and the noise dispersion addition value σ ² _add = 1.00 × 10 ^-3 (C / N is equivalent to 30 dB). The dotted line with ◯ indicates the characteristics when the soft judgment and the noise dispersion addition value σ ² _add = 3.16 × 10 ^-3 (C / N is equivalent to 25 dB). The dotted line with × indicates the characteristics when the softness judgment and the noise dispersion addition value σ ² _add = 1.00 × 10 ^-2 (C / N is equivalent to 20 dB).

From the solid line with + in the case of no hardness determination and noise dispersion adjustment, it can be seen that an error occurs when the area reception C / N is 29 dB or more. Further, from the solid line with (1) in the case of no soft determination and no noise dispersion adjustment, it can be seen that an error occurs when the area reception C / N is 33 dB or more.

On the other hand, the noise dispersion adjustment is performed from the dotted line with △ and the dotted line with ○ such as noise dispersion addition value σ ² _add = 1.00 × 10 ^-3 and noise dispersion addition value σ ² _add = 3.16 × 10 ^-3 (reduction). In the case of performing processing), it can be seen that the error is resolved when the area reception C / N is high.

The required C / N is defined as the area reception C / N that achieves BER = 1.00E-07. From FIG. 24, the required C / N is 20.7 dB in the case of AWGN (without relay), 21.1 dB in the case of no noise dispersion adjustment, and 21 in the case of the noise dispersion addition value σ ² _add = 1.00 × 10 ^-3 . .1 dB, 21.3 dB when the noise dispersion addition value σ ² _add = 3.16 × 10 ^-3 , and 22.1 dB when the noise dispersion addition value σ ² _add = 1.00 × 10 ⁻² .

Further, the larger the noise dispersion addition value σ ² _add , that is, the larger the noise dispersion adjustment value σ ' ² , the greater the effect of suppressing an error in the high area reception C / N, but the required C / N increases. , It is a trade-off relationship.

Therefore, the noise variance adjustment value σ ' ² needs to be set to the optimum value, that is, the noise variance addition value σ ² _{add obtained} from a predetermined function also needs to be set to the optimum value. In the first embodiment, a predetermined function (a function for obtaining the noise dispersion addition value σ ² _add from the relay station reception C / N) used by the degenerate amount information generation unit 24 of the relay device 2-1 shown in FIG. 3 is optimal. It is necessary to make it. Further, in the second embodiment, it is necessary to optimize the correspondence table shown in FIG. 17 generated by the correspondence table generation unit 17 of the transmission device 1-2 shown in FIG. The correspondence table is generated using a predetermined function.

The predetermined function is defined in advance so that the BER is equal to or less than the predetermined value in the predetermined range in which the area reception C / N is high in the BER characteristic shown in FIG. 24, for example. The same applies when a table is used instead of a function.

(Simulation result for clip method)
Next, the simulation result when the degeneracy method is the clip method will be described. FIG. 25 is a diagram showing simulation specifications (in the case of the clip method). In the simulation specifications of the clip method, the hierarchy, modulation, coding rate, SP arrangement, and relay conditions are as shown in FIG.

FIG. 26 is a diagram showing BER characteristics (in the case of the clip method) obtained by simulation. The horizontal axis represents area reception C / N [dB], and the vertical axis represents BER. The dotted line shows the characteristics when AWGN (without relay), that is, the receiving device 3 directly receives the broadcast wave from the transmitting device 1, and the solid line with * shows the characteristics when the symbol determination is not performed. The solid line with (1) shows the characteristics in the case of no soft judgment and no noise dispersion adjustment (no degeneration processing). The dotted line with □ shows the characteristics when the softness judgment and noise dispersion clip value σ ² _clip = 1.00 × 10 ^-3 (C / N is equivalent to 30 dB).

When there is no noise dispersion adjustment and when the area reception C / N is high from the solid line with ■ and the dotted line with □ when the noise dispersion clip value σ ² _clip = 1.00 × 10 ^-3 , there is no noise dispersion adjustment. It can be seen that the error that occurs in is suppressed by the clip processing.

The required C / N is defined as an area reception C / N that achieves BER = 1.00E-7. From FIG. 26, the required C / N is 21.1 dB when the noise dispersion adjustment is not performed, and 21.1 dB when the noise dispersion clip value σ ² _clip = 1.00 × 10 ^-3 , and the deterioration of the required C / N is eliminated. It turns out that it will be done.

In the case of the clip method, deterioration of the required C / N can be prevented by setting the noise dispersion clip value σ ² _clip so that the noise dispersion estimated value σ ² is not adjusted in the vicinity of the required C / N.

Therefore, it is necessary to appropriately set the noise dispersion clip value σ ² _clip according to the position where an error occurs in the high area reception C / N. In the first embodiment, a predetermined function (a function for obtaining the noise dispersion clip value σ ² _clip from the relay station reception C / N) used by the degenerate amount information generation unit 24 of the relay device 2-1 shown in FIG. 3 is optimal. It is necessary to make it. Further, in the second embodiment, it is necessary to optimize the correspondence table shown in FIG. 18 generated by the correspondence table generation unit 17 of the transmission device 1-2 shown in FIG. The correspondence table is generated using a predetermined function.

The predetermined function is defined in advance so that the BER is equal to or less than the predetermined value in the predetermined range in which the area reception C / N is high in the BER characteristic shown in FIG. 26, for example. The same applies when a table is used instead of a function.

Although the present invention has been described above with reference to Examples 1 and 2, the present invention is not limited to the above Examples 1 and 2, and can be variously modified without departing from the technical idea.

In the above-mentioned Example 2, the transmission device 1-2 shown in FIG. 15 transmits the broadcast wave including the corresponding table. On the other hand, when the transmitting device 1-2 and the receiving device 3-2 are connected by communication such as the Internet, the transmitting device 1-2 transmits the corresponding table to the receiving device 3-2 via the Internet. You may do so. Further, the relay device 2-2 may transmit the corresponding table to the receiving device 3-2 via the Internet.

Further, in the above-described second embodiment, the broadcast signal generation unit (not shown) of the transmission device 1-2 shown in FIG. 15 stores the corresponding table in, for example, the ES, fixed reception and partial reception data broadcasting area, or LLch. , Changed to generate a broadcast signal including the corresponding table.

Here, it is assumed that the broadcast signal generation unit (not shown) of the transmission device 1-2 stores the corresponding table in the data broadcasting area of fixed reception and partial reception, respectively.

The LLR processing unit 33 of the receiving device 3-2 shown in FIG. 20 performs LLR processing using the signal in the data broadcasting region of the fixed reception of the broadcasting signal, and the LDPC decoding unit 34 performs the corresponding table in the LDPC decoding processing. Extract and output the corresponding table to the degenerate amount information reading unit 36.

In this case, in the initial state, the LLR processing unit 33 performs LLR processing using the signal in the data broadcasting area of the fixed reception of the broadcast signal, and the LDPC decoding unit 34 cannot extract the corresponding table by the LDPC decoding process. Suppose.

When the corresponding table cannot be extracted in the initial state, the LDPC decoding unit 34 outputs an instruction to switch the fixed reception to the partial reception to the LLR processing unit 33. Alternatively, if the corresponding table cannot be input from the LDPC decoding unit 34 in the initial state, the degenerate amount information reading unit 36 outputs an instruction to switch the fixed reception to the partial reception to the LLR processing unit 33.

When the LLR processing unit 33 inputs an instruction to switch the fixed reception to the partial reception from the LDPC decoding unit 34 or the degenerate amount information reading unit 36, the LLR processing unit 33 switches from the fixed reception to the partial reception and switches the signal in the data broadcasting area of the partial reception of the broadcast signal. LLR processing is performed using. Then, the LDPC decoding unit 34 extracts the corresponding table by the LDPC decoding process. In general, partial reception has higher tolerance than fixed reception, so that the processing of the LLR processing unit 33 is switched from fixed reception to partial reception, so that the LDPC decoding unit 34 can increase the possibility of extracting the corresponding table. ..

As a result, the degenerate amount information reading unit 36 can input the corresponding table from the LDPC decoding unit 34, the degenerate processing is performed in the LLR processing unit 33, and the occurrence of errors is suppressed. Then, the LLR processing unit 33 switches from partial reception to fixed reception. In this way, the data broadcasting area for partial reception of the broadcasting signal can be used as a safety net for recovering from an error in the initial state.

The transmitting device, relay device, and receiving device according to the present invention are useful for broadcasting wave relay by a terrestrial broadcasting system of an advanced terrestrial broadcasting system.

1,1-1,1-2,100,110 Transmitter 2,2-1,2-2,200,210 Relay device 3,3-1,3-2,300,310 Receiver 10,101 LDPC code Chemical unit 11, 15, 27, 102, 104, 205 Modulation unit 12, 24 Degradation amount information generation unit 13, 25, 103, 204 TxID generation unit 14, 26 Multiple information generation unit 16, 28 Synthesis unit 17 Corresponding table generation unit 20,30,201,301 Channel equalization unit 21,202 Symbol determination unit 22,203 Remodulation unit 23 Relay station reception C / N estimation unit 31 Multiplex information extraction unit 32 Demodition unit 33 LLR processing unit 34,303 LDPC decoding Units 35, 304 TxID extraction unit 36 Decline amount information reading unit 40 Noise dispersion estimation unit 41, 41-1, 41-2 Noise dispersion adjustment unit 42, 302 LLR calculation unit 150, 250 Transmission line σ ² _add Noise distribution addition value σ ² _clip Noise dispersion clip value σ ² Noise dispersion estimated value σ ' ² Noise dispersion adjustment value x _I , x _Q Signal after channel equalization

Claims (9)

In a transmission device that applies LDPC coding to a broadcast signal, modulates the signal after LDPC coding, and transmits a broadcast wave of a main line signal.
A degenerate amount information generation unit that generates information on the degeneracy of the LLR when the receiving device that receives the broadcast wave calculates the LLR (log-likelihood ratio) as degenerate amount information.
A modulation unit that modulates the degenerate amount information generated by the degenerate amount information generation unit to generate a degenerate amount information signal.
A compositing unit that synthesizes the main line signal and the degenerate amount information signal generated by the modulation unit, and a compositing unit.
A transmission unit for transmitting the broadcast wave including the main line signal synthesized by the synthesis unit and the degenerate amount information signal is provided.
The degenerate amount information generation unit is
A transmission device for generating the degenerate amount information indicating that the degenerate process is off without performing the degenerate process for degenerating the LLR. The broadcast wave transmitted from the transmission device is received, the signal of the broadcast wave is equalized to the transmission line, the signal after the equalization of the transmission line is subjected to symbol determination, and the signal after the symbol determination is remodulated to the main line. In a relay device that retransmits a broadcast wave of a signal
A relay station reception C / N estimation unit that estimates the C / N ratio in the relay device as a relay station reception C / N based on the signal after equalization of the transmission line.
Using a predetermined function or table, the receiving device that receives the broadcast wave receives the data corresponding to the relay station reception C / N estimated by the relay station reception C / N estimation unit, and the LLR (log-likelihood ratio). ), And the degenerate amount information generation unit generated as the degenerate amount information regarding the degeneracy of the LLR.
A modulation unit that modulates the degenerate amount information generated by the degenerate amount information generation unit to generate a degenerate amount information signal.
A compositing unit that synthesizes the main line signal and the degenerate amount information signal generated by the modulation unit, and a compositing unit.
A transmission unit for transmitting the broadcast wave including the main line signal synthesized by the synthesis unit and the degenerate amount information signal is provided.
The degenerate amount information generation unit is
The higher the relay station reception C / N, the lower the degree of degeneration of the LLR, and the lower the relay station reception C / N, the higher the degree of degeneration of the LLR. A relay device characterized by generating quantity information. In the relay device according to claim 2,
The degenerate amount information generation unit is
Noise dispersion estimated value estimated from the signal after the transmission line equalization as a process for reducing the LLR when the receiving device calculates the LLR from the signal after the transmission line equalization and the noise dispersion adjustment value σ ' ² . When using the addition method to obtain the noise variance adjustment value σ ' ² by adding the noise variance addition value σ ² _add to σ ²
The higher the relay station reception C / N is, the smaller the noise dispersion addition value σ ² _add is, and the lower the relay station reception C / N is, the larger the noise dispersion addition value σ ² _add is. In addition, the noise variance addition value σ ² _add is generated as the regression amount information.
As a process for degrading the LLR, when the noise dispersion estimated value σ ² estimated from the signal after equalization of the transmission path is equal to or larger than the noise dispersion clip value σ ² _clip , the noise dispersion estimated value σ ² is adjusted to the noise variance. When a clip process is used in which the value σ ' ² is set and the noise dispersion estimated value σ ² is less than the noise dispersion clip value σ ² _clip , and the noise dispersion clip value σ ² _clip is set to the noise dispersion adjustment value σ ' ² . To,
The higher the relay station reception C / N is, the smaller the noise dispersion clip value σ ² _clip is, and the lower the relay station reception C / N is, the larger the noise dispersion clip value σ ² _clip is. In addition, the relay device is characterized in that the noise dispersion clip value σ ² _clip is generated as the shrinkage amount information. In the relay device according to claim 2 or 3, the relay device
The relay station reception C / N estimation unit is
Based on the signal after the transmission line equalization, the relay station reception C / N in the entire band or the relay station reception C / N for each segment is estimated.
The degenerate amount information generation unit is
Using the predetermined function or table, data corresponding to the relay station reception C / N in the entire band estimated by the relay station reception C / N estimation unit is generated as the degeneration amount information in the entire band. The relay device is characterized in that data corresponding to the relay station reception C / N for each segment is generated as the degenerate amount information for each segment. The broadcast wave transmitted from the transmission device and the relay device is received, the signal of the broadcast wave is equalized to the transmission line, the LLR (log-like probability ratio) is calculated from the signal after the equalization of the transmission line, and LDPC decoding is performed. In the receiving device that restores the broadcast signal
An extraction unit that extracts a degenerate amount information signal from the broadcast wave signal,
A demodulation unit that demodulates the degenerate amount information signal extracted by the extraction unit to obtain degenerate amount information, and a demodulation unit.
A LLR processing unit that calculates the LLR based on the signal after the transmission line equalization and the degeneracy amount information obtained by the demodulation unit is provided.
The LLR processing unit is
A noise variance estimation unit that estimates the noise variance estimated value σ ² based on the signal after equalization of the transmission path, and a noise variance estimation unit.
Based on the degeneracy amount information, the noise dispersion estimated value σ ² estimated by the noise dispersion estimation unit is adjusted, and the noise dispersion adjustment value σ ' ² is obtained.
A LLR calculation unit that calculates the LLR based on the signal after the transmission line equalization and the noise dispersion adjustment value σ ' ² obtained by the noise dispersion adjustment unit is provided.
The degeneracy amount information when the broadcast wave transmitted from the transmission device is received is used as data indicating that the degeneration process is not performed to degenerate the LLR.
The higher the relay station reception C / N, which is the C / N ratio in the relay device, the higher the degree of degeneracy of the degenerate amount information when the broadcast wave transmitted from the relay device is received. The data indicates the degree of degeneration of the LLR so that the lower the relay station reception C / N, the higher the degree of degeneration of the LLR.
The noise dispersion adjusting unit is
When the degeneration amount information indicates that the degeneration process is off, the noise dispersion estimated value σ ² is set as the noise dispersion adjustment value σ ' ² .
When the degeneracy amount information indicates the degree of degeneration of the LLR, the receiving device is characterized in that the noise dispersion adjustment value σ ' ² reflecting the degree of degeneracy of the LLR is obtained. In the receiving device according to claim 5,
The noise dispersion adjusting unit is
When the addition method is used as the process of reducing the LLR and the noise dispersion addition value σ ² _add is generated as the reduction amount information by the transmission device and the relay device, the noise is added to the noise dispersion estimated value σ ² . The variance addition value σ ² _add is added to obtain the noise dispersion adjustment value σ ' ² .
When the clip method is used as the process of reducing the LLR and the noise dispersion clip value σ ² _clip is generated as the reduction amount information by the transmission device and the relay device, the noise dispersion estimated value σ ² is the noise. When the dispersion clip value σ ² _clip or more, the noise dispersion estimated value σ ² is set as the noise dispersion adjustment value σ ' ² , and when the noise dispersion estimated value σ ² is less than the noise dispersion clip value σ ² _clip , the noise. A receiving device characterized in that the dispersion clip value σ ² _clip is set to the noise dispersion adjustment value σ ' ² . The broadcast signal is LDPC-encoded, the LDPC-encoded signal is modulated to generate a main line signal, and the TxID (identification signal) of its own device is modulated to generate a modulated TxID. In a transmission device that transmits a signal and a broadcast wave that combines the modulated TxID.
A receiving unit that receives the relay station reception C / N, which is the C / N ratio estimated by the relay device that receives the broadcast wave transmitted from the transmission device, and the TxID of the relay device from the relay device.
Degeneration processing in which the receiving device that receives the broadcast wave transmitted from the transmission device and the broadcast wave retransmitted from the relay device does not perform the degeneration process when calculating the LLR (log-likelihood ratio). Generates degenerate amount information indicating off,
The higher the relay station reception C / N received by the receiver using a predetermined function or table, the lower the degree of degeneration of the LLR, and the lower the relay station reception C / N. The degenerate amount information indicating the degree of degeneracy of the LLR is generated so that the degree of degeneration of the LLR becomes higher.
Correspondence including the degeneracy amount information indicating the TxID of the transmission device and the degeneration processing off corresponding to the TxID, and the degeneration amount information indicating the degree of degeneration of the TxID of the relay device and the LLR corresponding to the TxID. Corresponding table generator to generate a table and
A broadcast signal generation unit that generates the broadcast signal including the corresponding table generated by the corresponding table generation unit, and a broadcast signal generation unit.
A compositing unit that synthesizes the main line signal generated by subjecting the broadcast signal generated by the broadcast signal generation unit to the LDPC coding and the modulation, and the TxID after the modulation.
A transmission unit that transmits the broadcast wave including the main line signal and the TxID synthesized by the synthesis unit, and the transmission unit.
A transmitter characterized by being equipped with. In the transmitter according to claim 7,
The broadcast signal generation unit
A transmission device characterized in that the corresponding table is stored in a data broadcasting area of fixed reception and partial reception of the broadcast signal, and the broadcast signal including the corresponding table is generated. The broadcast wave transmitted from the transmission device and the relay device according to claim 7 is received, the signal of the broadcast wave is equalized to a transmission line, and the signal after the transmission line equalization is used as an LLR (log-like probability ratio). In the receiving device that calculates and performs LDPC decoding and restores the broadcast signal
An extraction unit that extracts the TxID (identification signal) of the transmission device and the TxID of the relay device from the broadcast wave signal.
Degenerate amount information that reads the degenerate amount information corresponding to the TxID extracted by the extraction unit from the corresponding table restored by calculating LLR from the signal after the transmission line equalization and performing LDPC decoding. The reading unit and
A LLR processing unit that calculates the LLR based on the signal after the transmission line equalization and the degenerate amount information read by the degenerate amount information reading unit is provided.
The LLR processing unit is
A noise variance estimation unit that estimates the noise variance estimated value σ ² based on the signal after equalization of the transmission path, and a noise variance estimation unit.
The noise dispersion estimated value σ ² estimated by the noise dispersion estimation unit is adjusted based on the reduction amount information read by the reduction amount information reading unit, and the noise dispersion adjustment value σ ' ² is obtained. Adjustment part and
A LLR calculation unit that calculates the LLR based on the signal after the transmission line equalization and the noise dispersion adjustment value σ ' ² obtained by the noise dispersion adjustment unit is provided.
The noise dispersion adjusting unit is
When the degeneration amount information indicates that the degeneration process is off, the noise dispersion estimated value σ ² is set as the noise dispersion adjustment value σ ' ² .
When the degeneracy amount information indicates the degree of degeneration of the LLR, the receiving device is characterized in that the noise dispersion estimated value σ ² reflecting the degree of degeneracy of the LLR is obtained.

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