WO2021140819A1 - Dispositif de détection de signal - Google Patents

Dispositif de détection de signal Download PDF

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Publication number
WO2021140819A1
WO2021140819A1 PCT/JP2020/045839 JP2020045839W WO2021140819A1 WO 2021140819 A1 WO2021140819 A1 WO 2021140819A1 JP 2020045839 W JP2020045839 W JP 2020045839W WO 2021140819 A1 WO2021140819 A1 WO 2021140819A1
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signal
standby
signal detection
unit
standby signal
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PCT/JP2020/045839
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English (en)
Japanese (ja)
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水谷　圭一
原田　博司
武 松村
愛富 酒井
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国立大学法人京都大学
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J13/00—Code division multiplex systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes

Definitions

  • the present invention relates to a signal detection device in a dynamic frequency sharing system.
  • the 5th generation mobile communication system whose full-scale operation is imminent, is expected to be a technology that can cope with this problem because it can communicate at a higher speed and a larger capacity than before.
  • 5G 5th generation mobile communication system
  • the allocation of 3.7GHz band, 4.5GHz band, and 28GHz band to 5G has already been decided, but the total allocated bandwidth is 500MHz or 600MHz for each operator, especially wireless of 6GHz or less.
  • the allocation is limited to about 100 MHz, which is by no means sufficient.
  • the frequency band assigned to the existing system primary user
  • other systems can specify or detect the place and time that the primary user is not operating, and other systems can operate under the condition that they do not interfere with the neighboring primary users.
  • Dynamic frequency sharing systems for secondary use are attracting attention.
  • the band that can be used by the secondary user is called white space. Research and development to detect and utilize this white space has been studied in Japan and overseas (see Non-Patent Document 1).
  • LSA Licensed Shard Access
  • LR frequency sharing database
  • LC LSA Controller
  • LSA in Europe is operated based on a frequency sharing database because the primary user is a fixed station.
  • a portable wireless relay communication system Field Pickup Unit: FPU
  • FPU Field Pickup Unit
  • the FPU signal is high while the operation is based on the frequency sharing database.
  • a radio wave sensor that can detect accurately, more secure sharing can be expected. Further, as for the detection performance, it is necessary to reliably detect the signal level up to 10 dB lower than the noise level of the radio.
  • an object of the present invention is to provide a signal detection device capable of detecting even a very weak signal level.
  • the present invention includes a complex cross-correlation unit that performs complex cross-correlation calculation between a received signal and a standby signal.
  • the output of the complex cross-correlation section is supplied, and the signal detection section that generates the detection result of the target signal of the OFDM method is provided.
  • the standby signal is a signal detection device that includes a signal known on the receiving side that appears periodically in the time axis direction in the target signal.
  • the circuit scale of the signal detection circuit can be simplified by simplifying the standby signal used in the correlation circuit.
  • the effects described here are not necessarily limited, and any of the effects described in the present invention may be used.
  • the content of the present invention is not construed as being limited by the effects exemplified in the following description.
  • FIG. 1 is a schematic diagram showing a frame configuration of a wireless transmission system to which the present invention can be applied.
  • FIG. 2 is a block diagram showing a schematic configuration of a signal detection device according to an embodiment of the present invention.
  • FIG. 3 is a block diagram of an example of a complex cross-correlator.
  • 4 (a) and 4 (b) are waveform diagrams of the in-phase component and the orthogonal component of the quantized Partial-CP standby signal according to the embodiment of the present invention.
  • 5 (a) and 5 (b) are waveform diagrams of the in-phase component and the orthogonal component of the Full-CP standby signal according to the embodiment of the present invention, respectively.
  • FIG. 6 is a block diagram of an example of the signal detection unit of the sample addition method.
  • FIG. 7 is a diagram showing a processing flow of a signal detection device in which a sample addition method is applied to a complex cross-correlation result when a 1FC standby signal or a 1PC standby signal is used.
  • FIG. 8 is a block diagram of an example of a signal detection unit of the symbol addition method.
  • FIG. 9 is a diagram showing a processing flow of a signal detection device in which a symbol addition method is applied to a complex cross-correlation result when a 9FC standby signal or a 9PC standby signal is used.
  • FIG. 10 is a diagram showing a processing flow of a signal detection device in which a symbol addition circuit is applied to a complex cross-correlation result when a 1FC standby signal or a 1PC standby signal is used.
  • FIG. 11 is a block diagram of a signal detection unit having a configuration in which the addition unit of the signal addition unit of the symbol addition method is connected to the addition unit of the signal detection unit of the sample addition method, and the comparison unit is further connected.
  • FIG. 12 is a diagram showing a processing flow of a signal detection device to which a sample addition circuit is applied to a complex cross-correlation result when a 1FC or 1PC standby signal is used and then a symbol addition circuit is further applied.
  • FIG. 13 is a graph showing the signal detection rate (computer simulation) of the Full-CP standby signal (1FC standby signal and 9FC standby signal) with respect to SNR in the AWGN environment.
  • FIG. 14 is a graph showing a signal detection rate (computer simulation) of Full-CP standby signals (1FC standby signal and 9FC standby signal) with respect to SNR in a 3GPP EVA channel environment.
  • FIG. 15 is a graph showing the signal detection rate (computer simulation) for the SNR of the quantized Partial-CP standby signal (1PC standby signal and 9PC standby signal) in the AWGN environment.
  • FIG. 16 is a graph showing a signal detection rate (computer simulation) obtained in the process of generating a quantized Partial-CP standby signal when a signal that does not convert a time axis signal into a Walsh waveform is used as a standby signal. is there.
  • FIG. 17 is a graph showing the signal detection rate (computer simulation) for the SNR of the quantized Partial-CP standby signal (1PC standby signal and 9PC standby signal) in the 3GPP EVA channel environment.
  • ARIB STD-B57 compliant FPU system
  • ARIB STD-B57 is a standard for portable OFDM digital wireless transmission system for transmission of television broadcast program material operated in 1.2 GHz band and 2.3 GHz band, and the first edition was formulated in December 2013. It was completed and the 2.2th edition was published in January 2018.
  • ARIB STD-B57 is a unidirectional communication system, with orthogonal frequency division multiplexing (OFDM) as the multiplexing method, and 64QAM, 32QAM, 16QAM, 8PSK, QPSK, DQPSK, BQPSK, and DBPSK as the modulation method for each carrier. Has been adopted. In addition, half mode and full mode are defined as transmission modes, and the number of inverse fast Fourier transform (IFFT) points used in the OFDM modulator / demodulator is defined as 2,048 (2K mode) and 1,024 (1K mode). ing.
  • OFDM orthogonal frequency division multiplexing
  • the occupied bandwidth is 8.40 MHz in half mode and 17.19 MHz in full mode.
  • the maximum transmission bit rate is 51.0 Mbit / s in the half mode and 105.0 Mbit / s in the full mode.
  • two modes are defined: Single-Input Single-Output (SISO) and Multiple-Input Multiple-Output (MIMO) having a configuration of 2 ⁇ 2 transmitting and receiving antennas.
  • SISO Single-Input Single-Output
  • MIMO Multiple-Input Multiple-Output
  • evaluation is performed by the SISO, 2K mode, half mode, and Continuous Pilot (CP) method.
  • GI is evaluated assuming 1/8.
  • the present invention can be applied to the case of MIMO, the case of full mode, and the case of Scattered Pilot (SP) method. Further, the GI is also applicable to cases other than 1/8.
  • FIG. 1 shows an OFDM frame configuration in the 2K half-mode CP system of ARIB STD-B57.
  • a pilot signal which is a known signal, is assigned to both transmission and reception every eight carriers.
  • the OFDM frame consists of CP, Transmission and Multiplexing Configuration Control (TMCC), Auxiliary Channel (AC), Data, and Null. There are 841 subcarriers with indexes 0 to 840, and 106 carriers (CP carriers) correspond to CP.
  • the OFDM frame of FIG. 1 is IFFTed, and a guard interval (GI) is added to form an OFDM symbol. The OFDM symbol is then quadrature modulated.
  • GI guard interval
  • FIG. 2 shows a schematic configuration of a signal detection device according to an embodiment of the present invention.
  • the OFDM signal of SISO's CP method 2K half mode based on the ARIB STD-B57 to be detected has the fading channel folded on the time axis, received by the antenna, converted into an IF signal, and passed through the A / D converter. Is input to the signal detection device 1.
  • White Gaussian noise in the device is added to the signal input to the signal detection device 1.
  • the signal detection device 1 is composed of a complex cross-correlation unit 2 and a signal detection unit 3.
  • a detection target signal and a standby signal also referred to as a replica signal or a reference signal
  • the complex cross-correlation results of these signals are input to the signal detection unit 3 in the subsequent stage, and the detection results (detection / non-detection) calculated by the detection method described later are output.
  • FIG. 3 shows the configuration of an example of the complex cross-correlation unit 2.
  • the received signal converted into a digital signal by the A / D converter 4 is supplied to the quadrature modulation demodulator 21, and the demodulated output of the I component and the Q component is obtained.
  • the received signal may be a wireless signal, noise, or the like in addition to the detection target signal.
  • the I component is supplied to the cross-correlator 22, and the Q component is supplied to the cross-correlator 23.
  • the standby signal (I) is supplied to the cross-correlator 22, and the standby signal (Q) is supplied to the cross-correlator 23.
  • the output of the cross-correlator 22 is squared by the multiplier 24 and converted to electric power
  • the output of the cross-correlator 23 is squared by the multiplier 25 and converted to electric power.
  • the outputs of the multiplier 24 and the multiplier 25 are added by the adder 26 and output to the signal detection unit 3 (see FIG. 2).
  • the cross-correlators 22 and 23 determine the complex correlation of the two time complex signals represented by the following equation (1).
  • a signal (feature amount) known on the receiving side such as the FPU preamble or pilot signal uses the feature that the same pattern appears periodically for each OFDM symbol in the time axis direction, and the preamplifier or The standby signal is composed only of signal components known on the receiving side such as a pilot signal. Since the feature quantity to be detected by the standby signal is periodically included in the time direction, a periodic peak value appears in the output of the complex cross-correlation part. The pattern depends on the standby signal pattern.
  • “Full-CP standby signal” A plurality of examples of the standby signal according to the embodiment of the present invention will be described below.
  • the standby signal used in the complex cross-correlation unit a pattern known on the receiving side such as a pilot signal of a radio wave transmitted by the primary user and a preamble is used.
  • the “Full-CP standby signal” is a signal in which only the CP carrier is mapped among the OFDM signals conforming to the ARIB STD-B57 to be detected, and the other subcarriers are null.
  • FIGS. 4 (a) and 4 (b) show the in-phase component and the orthogonal component of the Full-CP standby signal, respectively. Since 106 CPs are inserted every 8 subcarriers in the frequency direction, a repeating pattern for 8 cycles is generated in the 1 OFDM symbol on the complex plane on the time axis. However, in the in-phase component and the orthogonal component, the positive and negative are reversed every period. Then, since the portion corresponding to 1/8 of the 1 OFDM symbol is added as the GI, a repeating pattern for a total of 9 cycles is generated. (If the GI length is other than 1/8, the cycle is repeated for 8 ⁇ GI length in addition to 8 cycles.
  • 2,304 samples having the repetition pattern for these 9 cycles (2,048 corresponding to 1 OFDM symbol)
  • a standby signal 9-cycle Full-CP standby signal (9FC standby signal)”.
  • a repeating pattern for one cycle composed of 256 samples is used as the standby signal (referred to as "1 cycle Full-CP standby signal (1FC standby signal)").
  • 1FC standby signal 1FC standby signal
  • the standby signal In the complex cross-correlation unit 2, it is desirable that the standby signal length and the number of quantization bits of the standby signal can be reduced in order to reduce the amount of calculation and simplify the circuit. Therefore, after limiting the number of CP carriers used for the standby signal, the standby signal is simplified by converting the time axis signal into a Walsh waveform (referred to as “quantized Partial-CP standby signal”).
  • the quantized Partial-CP standby signal is composed of only these 16 CP carriers, and is quantized by converting the time axis signal composed of each CP carrier into a Walsh waveform. That is, the number of quantization bits can be reduced to 2 bits for the in-phase component and 3 bits for the orthogonal component.
  • the CP carrier to be selected may be arbitrarily selected from these 16 carriers.
  • FIGS. 5 (a) and 5 (b) show in-phase components and orthogonal components of the quantized Partial-CP standby signal when the above 16 CP carriers are selected and generated, respectively.
  • the quantized Partial-CP standby signal has a repeating pattern for 9 cycles in the 1 OFDM symbol section including the guard interval.
  • a "9-cycle quantized Partial-CP standby signal (9PC standby signal)" whose standby signal is an OFDM symbol composed of 945 samples having a repetition pattern for 9 cycles, and 1 composed of 105 samples.
  • Two methods of "1 cycle quantization Partial-CP standby signal (1PC standby signal)" in which the repetition pattern for each cycle is used as the standby signal can be considered.
  • the present invention combines two methods, a “sample addition method” and a “symbol addition method”, as a signal detection method for improving the signal detection capability by utilizing the periodic peak value appearing as the output of the complex cross-correlation part.
  • a sample addition method and a symbol addition method
  • a symbol addition method as a signal detection method for improving the signal detection capability by utilizing the periodic peak value appearing as the output of the complex cross-correlation part.
  • FIG. 6 shows the signal detection unit 30 of the sample addition method. This method can be applied only when the 1FC standby signal and the 1PC standby signal are used.
  • the output z (t) of the complex cross-correlation unit is supplied to the addition unit 31.
  • the adding unit 31 has a cascade connection of eight M sample delay circuits, and is adapted to add the input / output of the cascade connection and the nine outputs taken out from between the stages.
  • the addition output of the addition unit 31 is supplied to the comparison unit 32.
  • the comparison unit 32 has a comparator to which an output (electric power) obtained by squared the absolute value of the added output z'(t) is supplied.
  • the added output is supplied to the threshold value determination unit via the switch SW1.
  • the threshold value determined by the threshold value determination unit is supplied to the comparator via the switch SW2 and compared with the power of the added output z'(t). For example, if the power of the added output z'(t) is larger than the threshold value, it is determined that the signal is detected.
  • FIG. 7 is a diagram showing a processing flow of a signal detection device in which a sample addition method is applied to a complex cross-correlation result when a 1FC standby signal or a 1PC standby signal is used.
  • the correlation result z (t) shows the number of repetition cycles in the 1OFDM symbol including the guard interval. Peak values appear (that is, 9 peak values appear when the GI length is 1/8).
  • the signal detection unit can improve the noise immunity of the signal detection capability by adding up these nine peak values.
  • the threshold value required for signal detection is calculated by calculating z'(t) with the switch SW1 in the figure turned on, the switch SW2 turned off, and the input to the complex cross-correlation part being noise only, and its power. Set to the maximum value of.
  • FIG. 8 shows a signal detection unit 40 of the symbol addition method. This method is applicable when all the proposed standby signals are used.
  • the output z (t) of the complex cross-correlation unit is supplied to the addition unit 41.
  • the adding unit 41 has (N-1) sequential connections of L sample delay circuits, and is adapted to add the input / output of the cascade connections and the N outputs taken out from between the stages.
  • the addition output of the addition unit 41 is supplied to the comparison unit 42.
  • the comparison unit 42 has a comparator to which an output (electric power) obtained by squared the absolute value of a signal obtained by multiplying the added output z'(t) by 1 / N is supplied.
  • the power of the signal obtained by 1 / N of the added output z'(t) is supplied to the threshold value determination unit via the switch SW3.
  • the threshold value determined by the threshold value determination unit is supplied to the comparator via the switch SW4, and is compared with the power of the signal obtained by 1 / N of the added output z'(t). For example, if the power is larger than the threshold value, it is determined that the signal is detected.
  • z'(t) is calculated with the switch SW3 in the figure turned on, the switch SW4 turned off, and the input to the complex cross-correlation part is noise only, and the maximum value of the power is calculated.
  • FIG. 9 is a diagram showing a processing flow of a signal detection device to which the symbol addition method is applied to the complex cross-correlation result when the 9FC standby signal or the 9PC standby signal is used.
  • a peak value appears in the correlation result z (t) for each 1 OFDM symbol including a guard interval.
  • This method improves the noise immunity of the signal detection capability by adding up the peak values of N lines while shifting the correlation result z (t) by 1 OFDM symbol.
  • FIG. 10 is a diagram showing a processing flow of a signal detection device in which a symbol addition circuit is applied to a complex cross-correlation result when a 1FC standby signal or a 1PC standby signal is used.
  • FIG. 12 is a diagram showing a processing flow of a signal detection device to which a sample addition circuit is applied to a complex cross-correlation result when a 1FC or 1PC standby signal is used and then a symbol addition circuit is further applied.
  • a plurality of radio wave sensors having the signal detection device having the above-described configuration are arranged in a distributed manner, and when even one of them detects the target signal, it is regarded as “signal detection” (that is, selective diversity), so that the fading environment can be used.
  • the signal detection performance of the above may be improved. Assuming that the fading paths between the FPU and each signal detection device are independent of each other, and assuming that the signal detection rate when a single signal detection device is used is pd, the signal detection Pd when S units of sensors are used. Can be expressed by the following equation (3).
  • Computer simulation The performance of the signal detection device and the standby signal according to the embodiment of the present invention is evaluated by computer simulation. Table 1 shows the specifications of the transmitted signal.
  • the OFDM signal of the CP method 2K half mode of the SISO mode is used as the transmission signal (detection target signal). Since the AC carrier of the transmission signal is not used, all of them are Null carriers.
  • the channel model will be AWSGN and 3GPP Extended Vehicle A (EVA) model.
  • EVA Extended Vehicle A
  • the sample addition method is applied, and the symbol addition method is also applied (see FIG. 11).
  • Determination of signal detection threshold In order to determine the signal detection threshold, only Gaussian noise whose power is standardized to 1 is input to the signal detection unit, and the probability (false positive rate) that the maximum value of the power-converted correlation signal exceeds a certain value is evaluated. , The level at which the false detection rate becomes 0% was set as the threshold value. Table 2 shows the threshold values for each standby signal and the number of symbol additions N. As the value of the number of symbol additions N is increased, the average value of the noise power after addition approaches 0 by the central limit theorem, and the threshold value can be reduced.
  • FIG. 13 shows the signal detection rate of the Full-CP standby signal (1FC standby signal and 9FC standby signal) with respect to SNR in the AWGN environment.
  • the SNR required to achieve the signal detection rate of 99% is approximately the same for the 1FC standby signal and the 9FC standby signal.
  • FIG. 14 shows the signal detection ratio of the Full-CP standby signal (1FC standby signal and 9FC standby signal) with respect to SNR in the 3GPP EVA channel environment.
  • the SNR required to achieve the signal detection rate of 99% is approximately the same for the 1FC standby signal and the 9FC standby signal.
  • the larger the number of symbol additions N, the more the signal can be detected even with a lower SNR, and 99% or more of the FPU signal with SNR -14 dB can be detected by 10 symbol additions.
  • FIG. 15 shows the signal detection ratio of the quantized Partial-CP standby signal (1PC standby signal and 9PC standby signal) with respect to SNR in the AWGN environment.
  • the SNR required to achieve the signal detection rate of 99% is approximately the same for the 1PC standby signal and the 9PC standby signal.
  • the larger the number of symbol additions N, the lower the signal detection becomes possible, and with 20 symbol additions, 99% or more of the FPU signal with SNR -11 dB can be detected.
  • FIG. 16 shows a case where a signal that does not convert the time axis signal into a Walsh waveform, which can be obtained in the process of generating the quantized Partial-CP standby signal, is used as the standby signal (that is, the CP carrier used for the Full-CP standby signal). The signal detection rate of the standby signal) is shown.
  • FIG. 17 shows the signal detection ratio for the SNR of the quantized Partial-CP standby signal (1PC standby signal and 9PC standby signal) in the 3GPP EVA channel environment.
  • the circuit scale of the radio wave sensor can be simplified by a simplified method in which the standby signal used in the correlation circuit is quantized by the Walsh waveform.
  • the present invention is not limited to the above-described embodiments, and various modifications based on the technical idea of the present invention are possible.
  • the present invention can be applied to a digital television signal other than the ARIB STD-B57 system, and can be applied to an OFDM system signal other than the digital television signal.

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Abstract

Le présent dispositif de détection de signal est pourvu d'une unité de corrélation croisée complexe qui effectue un calcul de corrélation croisée complexe sur un signal de réception et sur un signal de veille, et une unité de détection de signal à laquelle une sortie de l'unité de corrélation croisée complexe est fournie et qui génère un résultat de détection d'un signal d'objet MROF. Le signal de veille comprend un signal apparaissant périodiquement dans une direction d'axe temporel et connu du côté réception dans le signal d'objet.
PCT/JP2020/045839 2020-01-10 2020-12-09 Dispositif de détection de signal WO2021140819A1 (fr)

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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009284036A (ja) * 2008-05-20 2009-12-03 Mitsubishi Electric Corp 伝送路推定装置および方法

Patent Citations (1)

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Publication number Priority date Publication date Assignee Title
JP2009284036A (ja) * 2008-05-20 2009-12-03 Mitsubishi Electric Corp 伝送路推定装置および方法

Non-Patent Citations (3)

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HARADA, HIROSHI ET AL.: "A New Estimation Method of Propagation Characteristics Using Pilot-Data- Inserted OFDM Signals for High-Mobility OFDM TransmissionScheme", IEICE TRANSACTIONS ON COMMUNICATIONS, vol. E85-B, no. 5, 1 May 2002 (2002-05-01), pages 882 - 894, XP055840207 *
OBATA, KENTARO ET AL.: "Symbol Synchronization Scheme for Wide Area M2M Wireless Communication Systems", IEICE TECHNICAL REPORT, vol. 115, no. 189, 17 August 2015 (2015-08-17), pages 71 - 76 *
SAKAI, ATOM ET AL.: "High-efficient Sensing Methods of Primary Wireless Transmission System for Dynamic Spectrum Sharingbased 5G System", 2020 23RD INTERNATIONAL SYMPOSIUM ON WIRELESS PERSONALMULTIMEDIA COMMUNICATIONS (WPMC, 19 October 2020 (2020-10-19), XP033871753 *

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