JP5042072B2 - Wireless device and signal detection method - Google Patents

Description

  The present invention relates to a radio apparatus and a signal detection method for detecting a signal of another system from a reception signal on which a signal of another radio system is superimposed.

  In recent years, with the increase in wireless systems and the diversification of services, the available frequencies are tight. Therefore, in order to effectively use the frequency resource, only when the specific wireless system can recognize that the specific wireless system is not using the frequency band for which the specific wireless system is licensed at a certain time or place. There is a system called cognitive radio that can be used even in a wireless system that has not acquired a license (hereinafter referred to as a secondary usage system) (see, for example, Patent Document 1).

  In this cognitive radio, when a radio device of a secondary usage system performs communication, it does not interfere with a radio system (hereinafter referred to as a primary usage system) for which a license exists in the vicinity. Therefore, it is necessary to detect the signal of the primary usage system and recognize the usage status. Therefore, before starting communication, signals of other wireless systems sharing the frequency are detected and used based on the magnitude of received power in the available frequency band by comparing with a threshold value. A method of recognizing a frequency band and performing communication while avoiding use of the frequency band has been proposed (for example, see Patent Document 2).

  Here, FIG. 22 is a block diagram showing a configuration of a receiving circuit for detecting a signal of another wireless system based on the magnitude of the received power according to the prior art. In FIG. 22, the quadrature detection circuit 21 performs quadrature detection on the received signal and outputs it to an A / D (Analog to Digital) conversion circuit 22. The A / D conversion circuit 22 converts the analog signal input from the quadrature detection circuit 21 into a digital signal and outputs the digital signal to the demodulation circuit 23. The demodulation circuit 23 demodulates the digital signal input from the A / D conversion circuit 22 and outputs the obtained demodulated signal to the decoding circuit 24. The decoding circuit 24 decodes the demodulated signal input from the demodulating circuit 23 and outputs the received data obtained to the access control unit 13.

The signal detection unit 30-1 includes a reception power measurement circuit 31 and a determination circuit 32 in order to detect a signal of another wireless system from the reception signal. The received power measurement circuit 31 measures received power from the digital signal input from the A / D conversion circuit 22 and outputs the received power to the determination circuit 32. The determination circuit 32 determines whether the frequency is shared by another wireless system by comparing with the threshold value based on the magnitude of the received power, and supplies the determination result to the access control unit 13. The access control unit 13 recognizes a frequency band used in another wireless system based on the determination result, and performs communication while avoiding the use of the frequency band.
JP-A-8-307937 JP 2002-186019 A

  However, in the prior art, since the signal of the other wireless system is detected before the communication is started, the other wireless system starts the communication during the communication, and the signal of the other wireless system is completely set to the received signal. When superimposed, there is a problem that it is difficult for a wireless device of a single transmission / reception circuit to detect a signal of another wireless system.

  In addition, when another wireless system suddenly starts communication during communication, there is a problem in that it interferes with communication of the other wireless system.

  In addition, when a signal of another wireless system is superimposed on the received signal, there is a problem that it is difficult to demodulate the received signal by removing the influence of the signal of the other wireless system.

  The present invention has been made in view of such circumstances, and an object of the present invention is to detect signals of other wireless systems that arrive during communication, and to suddenly cause communication of other wireless systems. A radio apparatus capable of suppressing interference with other radio systems even when started, and capable of demodulating a received signal by removing the influence of signals of other radio systems It is to provide a signal detection method.

In order to solve the above-described problem, the present invention is a wireless device belonging to any wireless system that performs communication in an environment in which a plurality of different wireless systems share a frequency, and wireless communication that transmits and receives wireless signals. Means, a known signal table for holding known signals of other wireless systems, a received signal storing means for storing received signals, and a received signal storing means based on the known signals held in the known signal table. A reception signal conversion means for converting the stored reception signal; and a signal detection means for detecting a signal of the other radio system included in the reception signal based on a conversion result by the reception signal conversion means , The received signal converting means includes a replica creating means for creating a replica of a known signal corresponding to a plurality of arrival patterns based on the known signal, and the received signal Received signal dividing means for dividing the frequency component of the replica assigned to the same frequency as the frequency component of the received signal from the frequency component of the received signal, and an average value calculation for calculating an average value of the frequency components of the received signal after the division Means and a power calculation means for obtaining the power of the average value calculated by the average value calculation means, the signal detection means based on the power obtained by the power calculation means based on the power of the other radio system. A wireless device is characterized by detecting a signal .

  According to the present invention, in the above invention, a frequency specifying table that holds a known signal and a use frequency band of the other wireless system in association with each other, and the frequency specifying table is referred to and stored in the known signal table. Based on a known signal, a frequency band specifying means for specifying a use frequency band of the other radio system, and a frequency of a transmission signal based on the use frequency band of the other radio system specified by the frequency band specifying means Transmission waveform shaping means for performing waveform shaping to suppress transmission power of all or a part of the components, or the portion of the used frequency band.

  The present invention provides the average value calculated by the average value calculation means from each frequency component of the received signal after the division when detecting an incoming signal from a wireless device of the other wireless system in the above invention. Frequency component subtracting means for subtracting the received signal, and received signal multiplier means for multiplying the frequency component of the received signal after the subtraction by the frequency component of the replica of the known signal assigned to the same frequency as the frequency component of the received signal. Furthermore, it is characterized by comprising.

In order to solve the above-described problem, the present invention is a signal detection method for detecting a signal of another wireless system in an environment in which a plurality of different wireless systems share a frequency, and stores a received signal. A step of reading a known signal of the other wireless system stored in advance, a step of converting the stored received signal based on the known signal, and a received signal based on the conversion result see containing and determining for the presence of other wireless systems of signals, said step of converting, based on the known signal, creating a known signal replica corresponding to the plurality of incoming pattern, the received Dividing the frequency component of the replica assigned to the same frequency as the frequency component of the received signal from the frequency component of the signal; and Calculating the average value of the frequency components of the received signal and calculating the power of the calculated average value. In the determining step, the signal of the other radio system is calculated based on the power. It is a signal detection method characterized by detecting.

  According to the present invention, in the above invention, the step of holding the known signal of the other wireless system and the use frequency band in association with each other, and the utilization of the other wireless system based on the known signal of the other wireless system. A waveform for suppressing the transmission power of all or a part of the frequency components of the transmission signal or a part of the used frequency band based on the step of specifying the frequency band and the specified used frequency band of the other radio system And a step of performing shaping.

According to the present invention, in the above invention, when an incoming signal from a radio device of the other radio system is detected , the average value is calculated from the frequency components of the divided received signal. Subtracting the average value, multiplying the frequency component of the received signal after the subtraction by the frequency component of the replica of the known signal, and demodulating and decoding the received signal after the multiplication It is characterized by.

  According to the present invention, the wireless device converts the received signal accumulated using the known signal of at least one other wireless system to each known signal, so that the signal matching the known signal is at least When superimposed on one received signal, each received signal can be characterized with respect to a known signal used for conversion, and one or two or more simultaneously superimposed on the received signal from the result The signal of the wireless system can be detected.

  In addition, according to the present invention, the radio apparatus divides the frequency component of the replica of the known signal in the same frequency band from the frequency component of the received signal, and then averages the frequency component of the received signal to Elements other than those related to known signals of other wireless systems can be removed, and the presence or absence of signals of other wireless systems is determined and detected by the power of the elements related to known signals of other remaining wireless systems Can do.

  According to the present invention, the wireless device uses at least one known signal to specify a use frequency band of the other wireless system, and all or a part of the frequency components of the transmission signal or the use frequency band. By implementing the waveform shaping to suppress the transmission power of this part, it is possible to suppress interference with the other radio system and improve the signal detection accuracy of the other radio system.

  Further, according to the present invention, the radio apparatus uses the average value of the received signal before signal detection obtained by the received signal converting means to receive the signal before signal detection from each frequency component of the received signal after division. By subtracting the average value of the signal and multiplying each frequency component of the received signal after the subtraction by the frequency component of the replica of the known signal, the influence from other radio systems on the received signal is removed, and the received signal is Demodulated and decoded.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
A. First Embodiment FIG. 1 is a conceptual diagram for explaining a signal detection method according to a first embodiment of the present invention. FIG. 2 is a conceptual diagram showing the relationship between frequency bands FB-A and FB-B that can be used by system A and system B, respectively. In FIG. 1, system A is a wideband system using frequency band FB-A, to which wireless devices A-0 and A-1 belong, and system B is a narrowband system using frequency band FB-B. The wireless device B-1 belongs. As shown in FIG. 2, the system A and the system B share the frequency band FB-B. The radio devices A-0 and A-1 belonging to the system A implement the signal detection method of the present invention.

  Next, FIG. 3 is a block diagram showing a configuration of the radio apparatus according to the first embodiment of the present invention. In FIG. 3, the radio apparatus according to the first embodiment includes an antenna 100, an RF (Radio Frequency) circuit 101, a reception circuit 102, an access control unit 103, a transmission circuit 104, and a known signal table storage unit 105. The RF circuit 101 converts an RF signal received by the antenna 100 into a BB (Baseband) signal and outputs it to the receiving circuit 102, while converting the BB signal input from the transmission circuit 104 into an RF signal and transmits it from the antenna 100. To do. The receiving circuit 102 demodulates and decodes the BB signal input from the RF circuit 101 and outputs received data to the access control unit 103. The transmission circuit 104 encodes and modulates transmission data input from the access control unit 103 and outputs the created BB signal to the RF circuit 101.

  The access control unit 103 controls the reception circuit 102 and the transmission circuit 104 based on reception data input from the reception circuit 102 (for example, determination results such as header information and presence / absence of signals of other wireless systems). Control of the receiving circuit 102 includes, for example, resetting a determination threshold for signal detection. The control of the transmission circuit 104 includes, for example, suspension of use of a frequency band shared with other detected wireless systems, suppression of transmission power, and the like. In addition, the access control unit 103 acquires known signal information of another wireless system from the known signal table storage unit 105 and inputs the known signal information to the receiving circuit 102 and the transmitting circuit 104.

  Next, FIG. 4 is a block diagram showing a configuration of the receiving circuit 102 according to the first embodiment. In FIG. 4, the reception circuit 102 includes an orthogonal detection circuit 201, an A / D conversion circuit 202, a demodulation circuit 203, a decoding circuit 204, and a signal detection unit 300-1. The quadrature detection circuit 201 performs quadrature detection on the BB signal input from the RF circuit 101 and outputs it to the A / D conversion circuit 202. The A / D conversion circuit 202 converts the analog signal input from the quadrature detection circuit 201 into a digital signal and outputs the digital signal to the demodulation circuit 203. The demodulation circuit 203 demodulates the digital signal input from the A / D conversion circuit 202 and outputs the obtained demodulated signal to the decoding circuit 204. The decoding circuit 204 decodes the demodulated signal input from the demodulation circuit 203 and outputs the obtained received data to the access control unit 103. Note that the decoding circuit 204 includes deinterleaving processing, error correction decoding processing, descrambling processing, and the like.

  The signal detection unit 300-1 detects a signal of another wireless system from the received signal. The signal detection unit 300-1 includes a reception signal storage unit 301, a reception signal conversion circuit 302, and a determination circuit 303. The reception signal storage unit 301 stores the reception signal input from the A / D conversion circuit 202. The reception signal conversion circuit 302 converts the reception signal acquired from the reception signal storage unit 301 based on the known signal information 105-1 input from the access control unit 103, and outputs the result to the determination circuit 303. The determination circuit 303 determines the presence / absence of a signal of another wireless system based on the conversion result input from the reception signal conversion circuit 302 and outputs the determination result to the access control unit 103.

  Next, FIG. 5 is a block diagram showing a configuration of the transmission circuit 104 according to the first embodiment. In FIG. 5, the transmission circuit 104 includes an encoding circuit 501, a modulation circuit 502, a D / A conversion circuit 503, and an orthogonal modulation circuit 504. The encoding circuit 501 encodes the transmission data input from the access control unit 103 and outputs it to the modulation circuit 502. Note that the encoding circuit 501 includes interleaving processing, error correction encoding processing, scrambling processing, and the like. The modulation circuit 502 modulates the encoded data input from the encoding circuit 501 and outputs it to a D / A (Digital to Analog) conversion circuit 503. The D / A conversion circuit 503 converts the digital modulation signal input from the modulation circuit 502 into an analog signal and outputs the analog signal to the quadrature modulation circuit 504. The quadrature modulation circuit 504 performs quadrature modulation on the analog signal input from the D / A conversion circuit 503 and outputs it to the RF circuit 101 shown in FIG.

Next, the operation of the above-described first embodiment will be described.
FIG. 6 is a flowchart for explaining the signal detection method according to the first embodiment. First, in a state where the received signal is stored in the received signal storage unit 301, the access control unit 103 uses the known signal information 105- of another wireless system (system B in FIG. 1) sharing the frequency from the known signal table 105. 1 is acquired and input to the received signal conversion circuit 302 (step Sa1). The known signal information 105-1 is information on a part or all of a fixed pattern of a frame such as a preamble, a pilot symbol, or a beacon, for example. Next, the received signal conversion circuit 302 converts the received signal using a Fourier transform circuit, an averaging circuit, or the like based on the input known signal information, so that the other wireless system that the received signal receives is known. The influence of the signal part is emphasized (step Sa2).

  More specifically, in the received signal conversion process, Fourier transform or averaging is performed according to the characteristics of the known signal information. For example, the following conversion is performed. In the time axis direction, the signal used by the system of the first embodiment has randomness (average converges to a constant value such as 0), and the known signals of other wireless systems have no randomness, A signal component and signal power of a time-series signal are averaged within a certain period. Alternatively, averaging within a certain period is performed for each carrier after Fourier transform. Alternatively, in the frequency axis direction, when the signal used by the system of the first embodiment has randomness and the known signal of another wireless system does not have randomness, the time-series signal is converted into a frequency signal by Fourier transform. The signal component and the signal power are averaged for every one symbol or every several symbols after the conversion.

  And the determination circuit 303 determines the presence or absence of the signal of another wireless system from the said conversion result (step Sa3). If the other wireless systems sharing the frequency are a plurality of different wireless systems, the above-described operation is repeated using each known signal information for each wireless system. The average power obtained by the above-described conversion process has a property that it increases only when a known signal interferes. Therefore, when the average power as the conversion result is equal to or greater than a predetermined threshold, it is determined that the known signal used for the conversion is superimposed on the received signal. In this way, the wireless device according to the first embodiment detects the presence / absence of a signal from another wireless system.

B. Second Embodiment Next, a second embodiment of the present invention will be described.
FIG. 7 is a block diagram showing the configuration of the receiving circuit 102 that implements the signal detection method according to the second embodiment. In the receiving circuit 102 according to the second embodiment, the configuration of the signal detection unit 300-2 and the known signal replica creation unit 400 corresponding to the signal detection circuit 300-1 are added to the above-described first embodiment. It is different in point. Note that portions corresponding to those in FIG. 4 are denoted by the same reference numerals and description thereof is omitted.

  In FIG. 7, the signal detection unit 300-2 includes a series-parallel conversion circuit 311, an FFT circuit 312, a subcarrier component storage unit 313, a subcarrier division circuit 314, an averaging circuit 315, a threshold storage unit 316, and a determination circuit 303. ing. The serial-parallel conversion circuit 311 parallelly converts a series of digitized reception signals input from the A / D conversion circuit 202 in accordance with a predetermined FFT (Fast Fourier Transform) point number of the next Fourier transform to be performed. 312 is output. The FFT circuit 312 performs a Fourier transform of the number of FFT points on the received signal input in parallel from the serial / parallel conversion circuit 311, and outputs the subcarrier value decomposed into frequency components to the subcarrier component storage unit 313.

  The subcarrier component storage unit 313 stores the value of the subcarrier input from the FFT 312. The subcarrier division circuit 314 divides each frequency component of the corresponding replica from the frequency component of the received signal acquired from the subcarrier component storage unit based on the known signal replica acquired from the known signal replica storage unit 404 described later. Then, the value of each frequency component after division is output to the averaging circuit 315. The averaging circuit 315 obtains an average value of the divided frequency component values input from the subcarrier division circuit 314, calculates the power of the average value, and outputs it to the determination circuit 303. The threshold value storage unit 316 stores a threshold value when the determination circuit 303 determines the presence / absence of a signal of another wireless system, and this threshold value is reset and stored by the value input from the access control unit 103. . The determination circuit 303 compares the power of the average value input from the averaging circuit 315 with the threshold value acquired from the threshold value storage unit 316 to determine the presence / absence of a signal of another wireless system.

  Next, the known signal replica creation unit 400 includes an IFFT circuit 401, an incoming signal pattern creation unit 402, an FFT circuit 403, and a known signal replica storage unit 404. The IFFT circuit 401 performs inverse Fourier transform on the known signal obtained from the known signal information 105-1 input from the access control unit 103 by an IFFT (Inverse Fast Fourier Transform) circuit 401, and outputs the result to the incoming signal pattern creation unit 402 To do. The incoming signal pattern creation unit 402 creates all incoming signal patterns using the time signal input from the IFFT circuit 401 and outputs the incoming signal pattern to the FFT circuit 403. The FFT circuit 403 Fourier-transforms the known signal replica input from the incoming signal pattern creation unit 402 and outputs the result to the known signal replica storage unit 404. The known signal replica storage unit 404 stores a replica of the known signal input from the FFT circuit 403.

  If the known signal information 105-1 input from the access control unit 103 is a time component of the known signal, the IFFT circuit 401 may not be provided. The incoming signal pattern creation unit 402 is configured with, for example, a shift register, and creates a replica of a known signal with the arrival time shifted in consideration of the arrival time shift. Also, it consists of a known signal time signal storage unit, shift register and multiplier circuit, and adder circuit. The known signal time signal stored in the storage unit is shifted in arrival time by the shift register and attenuated by the multiplier circuit. In addition, a replica of the incoming known signal may be created by simulating the propagation path environment by superimposing with an adder circuit.

  In FIG. 7, the fact that the output signals of the known signal information 105-1 are in two lines indicates that parallel signals of frequency components are output. Therefore, when the output of the known signal information 105-1 is a time series signal, the output signal of the known signal information 105-1 is one series, and the IFFT circuit 401 is omitted.

Next, the operation of the above-described second embodiment will be described.
Here, FIG. 8 is a flowchart for explaining the signal detection method of the second embodiment. First, the access control unit 103 acquires known signal information from the known signal table 105 (step Sb1). Next, based on the known signal information input from the access control unit 103 to the known signal replica creating unit 400, the known signal replica creating unit 400 creates a known signal replica for each arrival pattern, and stores the known signal replica. The data is stored in the unit 404 (step Sb2). The subcarrier division circuit 314 uses the replica to divide the frequency component of the corresponding replica from the frequency component of the received signal after Fourier transform (step Sb3).

  Next, the averaging circuit 315 obtains the average value of the frequency components of the received signal after the division and the power of the average value (step Sb4). Thereafter, the determination circuit 303 compares the power of the average value with a threshold value, and determines the presence / absence of a signal of another wireless system (step Sb5). If the average power is greater than the threshold, it is determined that the signal of the other wireless system is “present” (step Sb6). On the other hand, if the average power is less than or equal to the threshold, It is determined that the system signal is “none” (step Sb7). Finally, the determination result is output to the access control unit 103, and the process ends.

  Next, FIG. 9 is a block diagram showing another configuration example of the receiving circuit 102 according to the second embodiment. The OFDM scheme is assumed as the transmission scheme of the illustrated receiving circuit 102. In FIG. 9, the reception circuit 102 includes a serial / parallel conversion circuit 211, an FFT circuit 212, a channel equalization circuit 213, a subcarrier demodulation circuit 214, and a parallel / serial conversion circuit 215. The serial-parallel conversion circuit 211 outputs a series of digitized reception signals input from the A / D conversion circuit 202 to the FFT circuit 212 in parallel according to a predetermined number of FFT points to be performed next. The FFT circuit 212 performs a Fourier transform of the number of FFT points on the received signal input in parallel from the serial / parallel conversion circuit 211, and stores the subcarrier value decomposed into frequency components into the channel equalization circuit 213 and the subcarrier component storage. To the unit 313.

  Channel equalization circuit 213 corrects the influence of the propagation path estimated by using a known signal such as a preamble for the subcarrier component input from FFT circuit 212, and outputs the result to subcarrier demodulation circuit 214. The subcarrier demodulation circuit 214 demodulates the frequency component of the received signal after correction input from the channel equalization circuit 213 and outputs it to the parallel-serial conversion circuit 215. The parallel / serial conversion circuit 215 rearranges the demodulated reception data input in parallel from the subcarrier demodulation circuit 214 in series and outputs the serialized data to the decoding circuit 205.

  As shown in FIG. 9, by adopting the OFDM system, the serial-parallel conversion circuit 211 and the FFT circuit 212 of the demodulation circuit can be shared with the signal detection unit 300-2-1. In addition, since a signal can be assigned to each frequency component of the transmission signal, it is possible to realize an averaging process performed for detecting a signal of another wireless system with a small number of OFDM symbols. The second embodiment also has an effect of eliminating the randomness of interference components due to signals of other wireless systems by dividing frequency components by known signals.

  In FIG. 9, the two output signals of the known signal information 105-1 indicate that a parallel signal of frequency components is output. Therefore, when the output of the known signal information 105-1 is a time series signal, the output signal of the known signal information 105-1 is one series, and the IFFT circuit 401 is omitted.

C. Third Embodiment Next, a third embodiment of the present invention will be described.
FIG. 10 is a block diagram showing the configuration of the wireless device according to the third embodiment. The parts corresponding to those in FIG. In FIG. 10, in addition to the configuration shown in FIG. 3, the radio apparatus according to the third embodiment is a frequency identification table that identifies the frequency band used by another radio system based on the known signal information acquired from the known signal table 105. 106 is provided. In the frequency specification table 106, a plurality of known signals used by other wireless systems and use frequency bands are stored in association with each other. Similarly, when other wireless systems use the same known signal for a plurality of frequency bands (channels), the known signal and all the used frequency bands are stored in association with each other.

  FIG. 11 is a block diagram showing the configuration of the transmission circuit 104 of the third embodiment. The parts corresponding to those in FIG. 11, the transmission circuit 104 includes a series-parallel conversion circuit 511, an FFT circuit 512, a waveform shaping circuit 513, an IFFT circuit 514, and a parallel-serial conversion circuit 515 in addition to the configuration of the first embodiment shown in FIG. ing. The serial / parallel conversion circuit 511 outputs the digital modulation signal input from the modulation circuit 502 to the FFT circuit 512 in parallel in accordance with the number of FFT points used for Fourier transform. The FFT circuit 512 performs Fourier transform on the digital modulation signal input in parallel from the serial / parallel conversion circuit 511 and outputs the digital modulation signal to the waveform shaping circuit 513.

  The waveform shaping circuit 513 shapes the waveform of the frequency domain of the signal input from the FFT circuit 512 based on the use frequency band of another wireless system input from the access control unit 103, and outputs the waveform to the IFFT circuit 514. . The IFFT circuit 514 performs inverse Fourier transform on the signal input from the waveform shaping circuit 513 and outputs the result to the parallel-serial conversion circuit 515. The parallel / serial conversion circuit 515 rearranges the parallel signals input from the IFFT circuit 514 in series and outputs the serial signals to the D / A conversion circuit 503.

  When the transmission method used is a method in which a transmission signal is generated in the frequency domain, such as OFDM, and is converted into a time signal by inverse Fourier transform, a waveform shaping circuit immediately before the IFFT circuit that performs inverse Fourier transform It is only necessary to insert 513.

Next, the operation of the third embodiment will be described.
Here, FIG. 12 is a flowchart showing an operation until waveform shaping at the time of transmission in the third embodiment. First, the access control unit 103 acquires known signal information from the known signal table 105 (step Sc1). Next, based on the known signal information, the frequency identification table is referred to, and the use frequency band of another wireless system is identified (step Sc2).

  The known signal table 105 stores all known signals of other wireless systems that share the frequency band used by the wireless device of the third embodiment. The process for acquiring the known signal information and the process for specifying the used frequency band are respectively executed for all known signals stored in the known signal table. Alternatively, by performing communication with other devices such as carrier sense, information on the surrounding communication environment is acquired, other wireless systems used in the vicinity are recognized, and a specific known signal is selected. It may be. In addition, when performing communication using the same wireless system as other wireless devices and acquiring communication environment information, a dedicated frequency band for sharing the communication environment information may be used.

  The access control unit 103 inputs information on the frequency band used by other wireless systems to the waveform shaping circuit 513 of the transmission circuit 104, and the waveform shaping circuit 513 enters the frequency domain based on the frequency bands used by other wireless systems. The transmission power of the frequency component of the converted transmission signal is adjusted, and the operation is terminated (step Sc3). Other operations are the same as those in the first embodiment and the second embodiment, and thus the description thereof is omitted.

  Here, FIG. 13 is a conceptual diagram illustrating an example of waveform shaping of the transmission signal of the system A using the relationship between the system A and the system B in the first embodiment in the third embodiment. PS-A and B indicate power spectra of transmission signals of the system A and the system B, respectively. The present invention acquires the known signal information having the PS-B characteristics of the system B, refers to the frequency specification table storage unit 106, and specifies the use frequency band FB-B of the system B. The FB-B information is input to the waveform shaping circuit 513 together with the transmission signal of the system A having the PS-A characteristic, and a transmission signal having the PS-A ′ characteristic is generated. By performing the process of attenuating the transmission power of a specific band by the waveform shaping circuit 513, PS-A ′ has the power attenuated only in the FB-B band of the power spectrum of the PS-A transmission signal. It becomes a waveform.

  As described above, according to the third embodiment, it is possible to obtain the effects of suppressing the interference with other radio systems and improving the detection accuracy of signals of other radio systems.

D. Fourth Embodiment Next, a fourth embodiment of the present invention will be described.
The fourth embodiment is a modification of the second embodiment described above.
FIG. 14 is a block diagram showing a configuration of the receiving circuit 102 according to the fourth embodiment. It should be noted that portions corresponding to those in FIG. In FIG. 14, the receiving circuit 102 of the fourth embodiment includes an interference cancellation circuit 351, a subcarrier multiplication circuit 352, an IFFT circuit 353, and a parallel / serial conversion circuit 354 in addition to the configuration shown in FIG. The interference cancellation circuit 351 stores each frequency component of the received signal after division input from the subcarrier division circuit 314 inside the signal detection unit 300-4, and calculates the average value obtained by the averaging circuit 315. Then, the frequency is subtracted from each frequency component of the received signal after the division and output to the subcarrier multiplication circuit 352.

  The subcarrier multiplication circuit 352 multiplies the frequency component of the signal input from the interference cancellation circuit 351 by the frequency component of the replica of the known signal used for division, and outputs the result to the IFFT circuit 353. IFFT circuit 353 performs inverse Fourier transform on the signal input from subcarrier multiplication circuit 352 and outputs the result to parallel-serial conversion circuit 354. The parallel / serial conversion circuit 354 rearranges the signals input in parallel from the IFFT circuit 353 in series. The switch 355 selectively selects either the input to the demodulation circuit 203, the output from the A / D conversion circuit 202, or the output from the parallel-serial conversion circuit based on the determination result output from the determination circuit 303. Switch to. When the transmission method is the OFDM method, the IFFT circuit 353 and the parallel / serial conversion circuit 354 can be omitted.

  As shown in FIG. 9, in the OFDM method employed in the second embodiment, the serial-parallel conversion circuit 211 and the FFT circuit 212 can be shared by both the demodulation process and the detection process. The detection process is divided into two parts after being converted into frequency components by the FFT circuit 212. Therefore, in the fourth embodiment, even if the OFDM method is adopted, the signal input to the demodulation circuit 203 after removing the interference may remain the frequency component, and therefore the IFFT circuit 353 and the parallel-serial conversion circuit 354 are omitted. Can do. However, if the signal input to the demodulation circuit 203 needs to be a time-series signal, the IFFT circuit 353 and the parallel-serial conversion circuit 354 cannot be omitted.

  In FIG. 14, the fact that the output signals of the known signal information 105-1 are in two lines indicates that a parallel signal of frequency components is output. Therefore, when the output of the known signal information 105-1 is a time series signal, the output signal of the known signal information 105-1 is one series, and the IFFT circuit 401 is omitted.

Next, the operation of the fourth embodiment will be described.
FIG. 15 is a flowchart showing the operation of the signal detection method according to the fourth embodiment. In FIG. 15, the process up to the process of determining the presence / absence of signals of other wireless systems shown in steps Sd1 to Sd7 is the same as steps Sb1 to Sb7 of the second embodiment shown in FIG. The determination from the presence / absence of the signal will be described.

  First, in step Sd6, when it is determined that there is a signal of another wireless system, the determination result is output to the access control unit 103, and the signal is input to the demodulation circuit 203 based on the determination result. The switch 355 is switched, and the average value is subtracted from each frequency component of the received signal after division with respect to symbols including signals of other wireless systems (step Sd8). Next, the frequency component of the received signal after subtraction is multiplied by the frequency component of the replica of the known signal used for division (step Sd9). Finally, the signal is input to the demodulation circuit 203, the demodulated signal is input to the decoding circuit 204, the decoded signal is output to the access control unit 103, and the operation ends. On the other hand, if it is determined in step Sd7 that there is no signal from another wireless system, the determination result is output to the access control unit 103 and the operation is terminated.

  As described above, according to the fourth embodiment, it is possible to remove the influence of known signals of other wireless systems superimposed on the received signal.

E. Effects Next, effects of the present invention will be described.
Here, in the signal detection method according to the second embodiment of the present invention, the arrival of a signal of another wireless system (hereinafter referred to as system B) in the simulation model of the system shown in FIG. sometimes correctly probability could not be detected P _{MD (probability} of Miss detection) and the probability P _FA detected by mistake at the time of non-arrival _(probability of False Alarm) and the evaluation results of the evaluation will be described.

  As a transmission system, OFDM is used, and a wireless system (hereinafter referred to as system A) including a wireless device that implements the above-described signal detection method is a wideband system, and system B is a narrowband system. It is assumed that the frequency is shared. Further, the ratio (SPR) of the signal reception power of the system A and the signal reception power of the system B was set to 3 dB. FIG. 1 compares the energy detection method using the peak value of the power of the receiving circuit for detection with the signal detection method of the present invention.

Figure 17 is a diagram carrier power to noise power density ratio (CNR) shows the relationship between _{P MD} and _{P FA} at 30 dB. For example, the P _{MD =} 10%, the signal detection method according to the second embodiment of the present invention, compared with the prior art, the effect can be reduced to 1 P _FA of about 5 minutes can be obtained. Further, FIG. 18 is a diagram showing the relationship between _P MD = when 10% CNR and _{P FA} in the present invention and comparison with prior art. Signal detection method according to the second embodiment of the present invention has an effect that it is possible to reduce the P _FA regardless of CNR.

Next, FIGS. 19 and 20 are diagrams illustrating evaluation results of the signal detection method using the waveform shaping of the transmission signal according to the third embodiment of the present invention under the simulation environment described above. Here, the waveform shaping is performed so that the transmission power of the frequency component of the signal of the system A in the shared frequency band is lowered by 3 dB. As shown in FIG. 19, _{P FA} in _P MD = 10% at CNR = 30 dB, by using the waveform shaping of the transmitted signal, it can be seen that to reduce the 1 further about 6 minutes. Also in relation _P MD = 10% when the CNR and _{P FA} shown in FIG. 20, it is possible to reduce the _{P FA} regardless of the CNR, it is possible to improve the detection accuracy of other wireless systems of the signal The effect is obtained.

  Next, FIG. 21 is a diagram illustrating an evaluation result of the signal detection method according to the fourth embodiment of the present invention under the above-described simulation environment. In FIG. 21, one packet is transmitted a plurality of times with 5 OFDM symbols (of which the first two symbols are known preamble signals) in both systems A and B, and the last two symbols of the five symbols of the received packet of system A are 2 shows packet error rate (PER) characteristics when receiving interference from a signal of system B. FIG. However, random data with an average value of 0 is used as transmission data, and channel equalization using a known preamble signal is used. However, interleaving / deinterleaving processing, error correction coding / decoding processing, and scrambling are used. / Descramble processing is not used. When CNR = 30 dB, PER can remove the influence of other radio systems from the received signal, so that an effect of improving about 40% as compared with the case where this method is not used can be obtained.

It is a conceptual diagram for demonstrating the signal detection method by 1st Embodiment of this invention. It is a conceptual diagram which shows the relationship of the frequency band FB-A and FB-B which can be used for the system A and the system B, respectively. It is a block diagram which shows the structure of the radio | wireless apparatus by 1st Embodiment of this invention. 2 is a block diagram showing a configuration of a receiving circuit 102 according to the first embodiment. FIG. 2 is a block diagram showing a configuration of a transmission circuit 104 according to the first embodiment. FIG. It is a flowchart for demonstrating the signal detection method by this 1st Embodiment. It is a block diagram which shows the structure of the receiving circuit 102 which implements the signal detection method by this 2nd Embodiment. It is a flowchart for demonstrating the signal detection method of this 2nd Embodiment. It is a block diagram which shows the other structural example of the receiving circuit 102 by this 2nd Embodiment. It is a block diagram which shows the structure of the radio | wireless apparatus by this 3rd Embodiment. It is a block diagram which shows the structure of the transmission circuit 104 of the 3rd embodiment. It is a flowchart which shows the operation | movement until it performs the waveform shaping at the time of transmission in the 3rd Embodiment. In this 3rd Embodiment, it is a conceptual diagram which shows an example of the waveform shaping of the transmission signal of the system A using the relationship of the system A and the system B in 1st Embodiment. It is a block diagram which shows the structure of the receiving circuit 102 by this 4th Embodiment. It is a flowchart which shows operation | movement of the signal detection method by this 4th Embodiment. It is a flowchart which shows the simulation conditions used in order to demonstrate the effect of this invention. Carrier power to noise power density ratio (CNR) is a diagram showing the relationship between _{P MD} and _{P FA} at 30 dB. In the present invention and comparison with prior art is a diagram showing the relationship between _P MD = when 10% CNR and _{P FA.} It is a figure which shows the evaluation result of the signal detection method using the transmission signal waveform shaping method of 3rd Embodiment of this invention. It is a figure which shows the evaluation result of the signal detection method using the transmission signal waveform shaping method of 3rd Embodiment of this invention. It is a figure which shows the evaluation result of the signal detection method using the received signal demodulation method of 4th Embodiment of this invention. It is a block diagram which shows the structure of the receiving circuit which detects the signal of another radio system based on the magnitude | size of receiving power by a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Antenna 101 RF circuit 102 Reception circuit 103 Access control part 104 Transmission circuit 105 Known signal table memory | storage part 105-1 Known signal information 106 Frequency specific table memory | storage part 106-1 Use frequency band information 201 Quadrature detection circuit 202 A / D conversion circuit DESCRIPTION OF SYMBOLS 203 Demodulation circuit 204 Decoding circuit 211 Serial-parallel conversion circuit 212 FFT circuit 213 Channel equalization circuit 214 Subcarrier demodulation circuit 215 Parallel-serial conversion circuit 300-1 Signal detection part 300-2 Signal detection part 300-2-1 Signal detection part 300 -4 Signal detection unit 301 Reception signal storage unit 302 Reception signal conversion circuit 303 Determination circuit 311 Series-parallel conversion circuit 312 FFT circuit 313 Subcarrier component storage unit 314 Subcarrier division circuit 315 Averaging circuit 316 Threshold storage unit 351 Dry Removal circuit 352 Subcarrier multiplication circuit 353 IFFT circuit 354 Parallel-serial conversion circuit 400 Known signal replica creation unit 401 IFFT circuit 402 Arrival signal pattern creation unit 403 FFT circuit 404 Known signal replica storage unit 501 Coding circuit 502 Modulation circuit 503 D / A Conversion circuit 504 Quadrature modulation circuit 511 Series-parallel conversion circuit 512 FFT circuit 513 Waveform shaping circuit 514 IFFT circuit 515 Parallel-serial conversion circuit

Claims (6)

A wireless device belonging to any wireless system that performs communication in an environment in which a plurality of different wireless systems share a frequency,
Wireless communication means for transmitting and receiving wireless signals;
A known signal table holding known signals of other wireless systems;
Received signal storage means for storing received signals;
Received signal conversion means for converting the received signal stored in the received signal storage means based on the known signal held in the known signal table;
Signal detecting means for detecting a signal of the other radio system included in the received signal based on a conversion result by the received signal converting means , and
The received signal converting means includes
Based on the known signal, replica creating means for creating a replica of a known signal according to a plurality of arrival patterns;
Received signal dividing means for dividing the frequency component of the replica assigned to the same frequency as the frequency component of the received signal from the frequency component of the received signal;
Average value calculating means for calculating an average value of frequency components of the received signal after the division;
Power calculating means for obtaining power of the average value calculated by the average value calculating means;
With
The radio apparatus characterized in that the signal detection unit detects a signal of the other radio system based on the power obtained by the power calculation unit . A frequency specification table that holds a known signal and a use frequency band of the other wireless system in association with each other;
A frequency band specifying means for referring to the frequency specifying table and specifying a use frequency band of the other radio system based on a known signal held in the known signal table;
Based on the use frequency band of the other radio system specified by the frequency band specifying means, the waveform shaping is performed to suppress the transmission power of all or part of the frequency components of the transmission signal, or the part of the use frequency band. The radio apparatus according to claim 1 , further comprising: a transmission waveform shaping unit that performs. A frequency component subtracting means for subtracting the average value calculated by the average value calculating means from each frequency component of the received signal after the division when an incoming signal from a wireless device of the other wireless system is detected;
The received signal multiplication means for multiplying the frequency component of the received signal after the subtraction by the frequency component of the replica of the known signal assigned to the same frequency as the frequency component of the received signal. Item 2. The wireless device according to Item 1 . A signal detection method for detecting a signal of another wireless system in an environment where a plurality of different wireless systems share a frequency,
Accumulating received signals;
Reading a known signal of the other wireless system stored in advance;
Converting the stored received signal based on the known signal;
On the basis of the conversion result, looking contains and determining for the presence of other wireless systems of the signal included in the received signal,
The converting step includes:
Creating a replica of a known signal according to a plurality of arrival patterns based on the known signal;
Dividing the frequency component of the replica assigned to the same frequency as the frequency component of the received signal from the frequency component of the received signal;
Calculating an average value of frequency components of the received signal after the division;
Determining the calculated average power;
Including
In the determining step, a signal of the other wireless system is detected based on the power . Holding the known signal and the use frequency band of the other wireless system in association with each other;
Identifying a used frequency band of the other radio system based on a known signal of the other radio system;
Performing waveform shaping to suppress the transmission power of all or part of the frequency components of the transmission signal or the portion of the use frequency band based on the specified use frequency band of the other radio system. The signal detection method according to claim 4 . Upon detecting an incoming signal from the wireless device of said other radio systems, the frequency components of the received signal after the division, and subtracting the average value calculated in the step of calculating the average value,
Multiplying the frequency component of the received signal after the subtraction by the frequency component of the replica of the known signal;
The signal detection method according to claim 4 , further comprising: demodulating and decoding the reception signal after the multiplication.

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