JP5306259B2 - Information compression apparatus and information compression method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an information compression device which compresses digital signals containing signals using a plurality of different frequency bands, without using a BPF requiring information on the center frequency, the signal band width, the modulation system etc. of a signal to be received. <P>SOLUTION: The information compression device includes: a time/frequency conversion unit which performs time/frequency conversion of a received signal obtained by receiving the signal which is transmitted from two or more wireless systems using different frequencies and thereby obtains frequency spectrum of the received signal; a no-signal frequency band determination unit which determines whether being a no-signal or not on the basis of the spectrum amplitude value of the frequency spectrum and replaces the signal of a band determined to be no-signal with the no-signal; and an information compression unit for compressing the signal from the no-signal frequency band determination unit. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an information compression apparatus and an information compression method for compressing a transmission signal between a broadband collective wireless transmission / reception system and a signal processing unit.

A broadband collective receiver that simultaneously accommodates a plurality of wireless systems using different bands receives all signals at once.
FIG. 1 shows an example of a multi-band wireless transceiver system.
In FIG. 1, a multi-band wireless transceiver 102 receives signals transmitted from a plurality of wireless devices using different wireless systems, and transmits signals to the signal processing unit 104 through the network 103. Here, the wireless system A wireless device 101A which is a wireless device in the wireless system A, the wireless system B wireless device 101B which is a wireless device in the wireless system B, and the wireless system C wireless device 101C which is a wireless device in the wireless system C are transmitted. The
When digital signals are used in the network 103 of FIG. 1, the analog / digital converter of the multi-band wireless transceiver 102 performs analog / digital conversion (hereinafter referred to as A / D conversion), and the received signal is converted into digital data. The
When performing this A / D conversion, there is a method of performing A / D conversion of all information as it is for the signals of all received wireless systems.

  As described above, if A / D conversion is performed on the received signal as it is, radio wave data that is data obtained by A / D conversion of the radio signal becomes enormous. A method of performing A / D conversion for a desired band by limiting with a limiting filter (hereinafter referred to as BPF) has been disclosed (for example, Non-Patent Document 1). According to this method, since signals outside the BPF band are not subjected to A / D conversion or transmission over the network, there is an advantage that a large transmission capacity is not required for the network.

Receiver Architectures for Software-defined Radios in Mobile Terminals: the Path to Cognitive Radios, Bourdoux Andre; Craninckx, Jan; Dejonghe, Antoine; Van der Perre, Liesbet, Radio and Wireless Symposium, 2007 IEEE, 9-11 Jan. 2007 Page ( s): 535-538

  However, in the method of performing A / D conversion without losing all the information in the multi-band wireless transceiver for the signals of all the radio systems received in a batch, the center frequency, signal bandwidth, and modulation of the received signals There is no need to obtain information such as the system, and there is a degree of freedom of operation, but it becomes necessary for the multiband radio transceiver to perform A / D conversion at a high sampling frequency. For this reason, the amount of signals generated by A / D conversion is enormous, and there is a problem that a large transmission capacity is required for the transmission network in order to transmit the signals as they are to the signal processing unit.

  On the other hand, in the method of performing A / D conversion after performing band limitation on the radio signal to be A / D converted in advance by BPF, a signal outside the BPF band is not subjected to A / D conversion or transmission over the network. Therefore, there is an advantage that a large transmission capacity requirement for the network is not required. However, in this method, it is necessary to obtain information such as the center frequency of the received signal, the signal bandwidth, and the modulation method from the viewpoint of setting the BPF, and there is a problem that the degree of freedom in operation is limited. there were.

  The present invention has been made in view of such circumstances, and an object of the present invention is to obtain a center frequency, a signal bandwidth, and a modulation of a received signal with respect to a digital signal including a signal using a plurality of different frequency bands. An information compression device capable of reducing both the transmission capacity required for the network to the signal processing unit and the freedom of operation by performing signal compression without using a BPF that requires information such as a method, An object is to provide an information compression method.

In order to solve the above-described problem, the present invention performs time / frequency conversion of a received signal on a received signal obtained by receiving signals transmitted from a plurality of wireless systems using different frequencies, and Based on the time / frequency conversion unit for obtaining a frequency spectrum and the spectrum amplitude value of the frequency spectrum, it is determined whether or not there is no signal, and a signal in a band determined to be no signal is replaced with no signal. A signal frequency band determination unit, an information compression unit for compressing a signal from the no-signal frequency band determination unit, and a spectrum amplitude value of a frequency spectrum obtained from the time / frequency conversion unit are measured, and a peak value of the spectrum amplitude value is measured. A peak spectrum amplitude value measuring unit for obtaining a spectrum amplitude value in a range that does not include the peak value of the spectrum amplitude value. A noise spectrum amplitude value measuring unit for obtaining a spectrum amplitude value, and measuring each frequency spectrum amplitude value on a high frequency side and a low frequency side from a frequency at which the spectrum amplitude value of the frequency spectrum peaks, and measuring the measured spectrum amplitude A noise level intersection frequency measurement unit that measures a frequency whose value is lower than the noise level, a peak value of the frequency spectrum and a frequency at which the peak is reached, a noise spectrum amplitude value, a frequency measurement value on the high frequency side, and the low frequency A signal band estimation unit that estimates a band between the frequency measurement value on the high frequency side and the frequency estimation value on the low frequency side as a signal band of the signal based on the frequency measurement value on the side And the no-signal frequency band determination unit converts the spectrum amplitude value in the signaled band estimated by the signaled band estimation unit to the spectrum amplitude value. In its leave original value, for the spectral amplitude value of the out-chromatic signal band, characterized in that no signal.

  In the present invention, time / frequency conversion is performed on a signal, a no-signal frequency band is detected, and information corresponding to the no-signal frequency band is compressed.

  In the information compression apparatus described above, the no-signal frequency band determination unit compares the no-signal determination threshold with the frequency spectrum, and a spectrum amplitude value of the frequency spectrum is equal to or greater than the no-signal determination threshold. If it is, the original value is maintained, and if the spectrum amplitude value of the frequency spectrum is less than the no-signal determination threshold, no signal is set.

  In this invention, in order to determine a frequency region where there is no signal, threshold determination is performed on a spectrum amplitude value obtained based on a certain threshold, a frequency band below the threshold is defined as a no signal band, Replace spectral amplitude values.

  Further, the present invention is the information compression apparatus described above, wherein the information compression unit converts the signal from the no-signal frequency band determination unit by compression by differential encoding, continuous length compression, and integer encoding by replacing with an integer value. The compression is performed by any one of compression by, compression by entropy coding, compression by universal coding, and compression by linear predictive coding.

  In the present invention, as a threshold value setting method used for threshold value determination, a peak of an amplitude value of a frequency spectrum is detected, and the threshold value is set based on the peak value.

  Further, the present invention provides the above-described information compression apparatus, wherein a peak spectrum amplitude value measurement unit that measures a spectrum amplitude value of a frequency spectrum obtained from the time / frequency conversion unit and obtains a peak value of the spectrum amplitude value; A threshold setting unit that calculates a no-signal determination threshold by multiplying a peak value of the obtained spectrum amplitude value by a constant, and the no-signal frequency band determination unit includes the no-signal determination threshold calculated by the threshold setting unit and The frequency spectrum is compared.

  In this invention, the peak of the frequency spectrum amplitude value is detected in order to determine the frequency region where there is no signal, the signaled band is estimated from the peak value and the noise spectrum amplitude value, and the spectrum amplitude value of the no signal frequency band is replaced. To do.

  Further, the present invention provides the above-described information compression device, wherein the spectrum amplitude value of the frequency spectrum obtained from the time / frequency conversion unit is measured to obtain a peak value of the spectrum amplitude value, and the spectrum A noise spectrum amplitude value measurement unit that measures a spectrum amplitude value in a range that does not include the peak value of the amplitude value, a frequency at which the spectrum amplitude value of the frequency spectrum peaks, and a frequency at which the spectrum amplitude value intersects the noise level Noise level intersection frequency measurement unit that performs the above, and the signal amplitude that estimates the signal band that is a signal based on the peak amplitude value and peak frequency of the frequency spectrum, and the noise frequency spectrum amplitude value and the frequency measurement value A band estimation unit, and the no-signal frequency band determination unit includes the signal band estimation. For the spectral amplitude value of the chromatic signal band estimated by parts leave the original value, for the spectral amplitude value of the out-chromatic signal band, characterized in that no signal.

  In the present invention, information compression is performed on the frequency spectrum in which the amplitude value of the no-signal frequency band is replaced, and the radio wave data is compressed.

In addition, the present invention provides a time / frequency conversion unit for a computer that performs time / frequency conversion of a received signal on a received signal obtained by receiving signals transmitted from a plurality of wireless systems using different frequencies. Obtaining the frequency spectrum of the signal, the peak spectrum amplitude value measurement unit of the computer measures the spectrum amplitude value of the frequency spectrum obtained from the time / frequency conversion unit, obtains the peak value of the spectrum amplitude value, and obtains the noise of the computer. A spectrum amplitude value measurement unit measures a spectrum amplitude value in a range not including a peak value of the spectrum amplitude value to obtain a noise spectrum amplitude value, and a noise level intersection frequency measurement unit of the computer performs a spectrum of the frequency spectrum. Each frequency from the frequency at which the amplitude value peaks to the high frequency side and low frequency side The spectrum amplitude value is measured, the frequency at which the measured spectrum amplitude value falls below the noise level is measured, and the signaled band estimation unit of the computer uses the peak value of the frequency spectrum and the peak frequency, and the noise spectrum. Based on the amplitude value and the frequency measurement value on the high frequency side and the frequency measurement value on the low frequency side, a band is provided between the frequency measurement value on the high frequency side and the frequency estimation value on the low frequency side. The no-signal frequency band determination unit of the computer determines whether or not there is no signal based on the spectrum amplitude value of the frequency spectrum, and determines whether the signal band is determined to be no signal. The information compression method is characterized in that the signal is replaced with no signal, and the information compression unit of the computer compresses the signal from the no-signal frequency band determination unit. It is.

In the present invention, A / D conversion is performed on a radio signal, and then a signal having an amplitude value of a frequency spectrum equal to or less than a threshold value is determined as no signal, and is compressed and transmitted over a network.
As a result, transmission necessary for the network reaching the signal processing unit can be performed without using a BPF that requires information such as the center frequency, signal bandwidth, and modulation method of the received signal in advance and by compressing the signal. It is possible to provide both capacity reduction and operational freedom. In addition, as shown in the numerical simulation results to be described later, the present invention has been confirmed to suppress deterioration of the code error rate (BER) even if information compression is performed by setting parameters (threshold value, compression rate). .

  As described above, according to the present invention, it is determined whether or not it is a no-signal band by using a spectrum amplitude value of a frequency spectrum obtained by subjecting a received signal to time / frequency conversion processing. The compression is performed by replacing the spectrum value with a value that is easy to compress. As a result, for a digital signal including a signal using a plurality of different frequency bands, the signal can be compressed without using a BPF that requires information such as the center frequency, signal bandwidth, and modulation method of the received signal. It can be carried out. Therefore, the transmission capacity required for the network to the signal processing unit can be reduced and the degree of freedom of operation can be compatible.

It is a block diagram of a multi-band wireless transmission / reception system. It is a block diagram showing the function of the information compression apparatus 200 in 1st Embodiment. 5 is a flowchart for explaining the operation of the information compression apparatus 200. It is a block diagram showing the function of the information compression apparatus 300 in 2nd Embodiment. 5 is a flowchart for explaining the operation of the information compression apparatus 300. It is a figure showing the simulation conditions of an information compression device. It is a figure which shows the evaluation result of the relationship between SNR and BER in comparison with 1st Embodiment and the existing technology. It is a figure which shows the relationship between SNR and compression rate in 1st Embodiment. It is a figure which shows the evaluation result of the relationship between SNR and BER in the comparison with 2nd Embodiment and the existing technology. It is a figure which shows the relationship between SNR and compression rate in 2nd Embodiment. It is a figure explaining the outline of the signal processing in 1st and 2nd embodiment. FIG. 5 is a diagram showing a waveform when performing a no-signal determination method in the first embodiment. It is a figure which shows the waveform in the case of performing the no signal determination method in 2nd Embodiment.

  Hereinafter, a broadband collective wireless transmission / reception system according to an embodiment of the present invention will be described with reference to the drawings. The broadband collective wireless transmission / reception system in the present embodiment is the same as the configuration of FIG. 1 described above, but the functions of the multi-band wireless transceiver 102 are different. Hereinafter, the information compression apparatus 200 in this embodiment will be described.

<< First Embodiment >>
FIG. 2 is a block diagram showing the function of the information compression apparatus 200 in this embodiment. The information compression apparatus 200 is mounted on the multiband radio transceiver 102, receives a received signal received by the multiband radio transceiver 102, performs information compression processing described below, and performs subsequent processing in the multiband radio transceiver 102. Output to the signal processor.
In this information compression apparatus 200, a time / frequency conversion unit 201 performs time / frequency conversion of a received signal on a received signal obtained by receiving signals transmitted from a plurality of wireless systems using different frequencies, and receives the received signal. Obtain the frequency spectrum of the signal. The peak spectrum amplitude value measuring unit 202 measures the spectrum amplitude value of the frequency spectrum obtained from the time / frequency converting unit 201 and obtains the peak value of the spectrum amplitude value. The threshold setting unit 203 calculates a no-signal determination threshold by multiplying the peak value of the spectrum amplitude value obtained by the peak spectrum amplitude value measuring unit 202 by a constant.

  The threshold determination / replacement unit 204 determines whether or not there is no signal for each band based on the spectrum amplitude value of the frequency spectrum, and replaces the signal in the band determined to be no signal with no signal. This threshold determination / replacement unit 204 compares the no-signal determination threshold calculated by the threshold setting unit 203 with the frequency spectrum, and if the spectrum amplitude value of the frequency spectrum is equal to or greater than the no-signal determination threshold, the original value signal If the spectrum amplitude value of the frequency spectrum is less than the no-signal determination threshold, no signal is set and these signals are encoded.

  The information compression unit 205 is one of a compression by differential encoding, a continuous length compression, a compression by integer encoding by replacing with an integer value, a compression by entropy encoding, a compression by universal encoding, and a compression by linear prediction encoding. Depending on what is compressed.

Next, the operation of the above-described information compression apparatus 200 will be described.
FIG. 3 shows a flow chart for obtaining 205 output signals from the input signals to 201 in FIG.
The time / frequency conversion unit 201 acquires a reception signal including signals of a plurality of different bands transmitted from the wireless devices of each wireless communication system (step S102), and performs time / frequency conversion processing to convert it into a frequency spectrum. (Step S104). The time / frequency conversion processing in step S104 includes discrete Fourier transform, fast Fourier transform, short-time Fourier transform, wavelet transform, Wigner distribution, and the like.

  When the time / frequency conversion process is performed, the peak spectrum amplitude value measuring unit 202 obtains the spectrum amplitude value from the in-phase component and the quadrature component of the frequency spectrum, and detects the peak amplitude value (step S106). As a peak detection method, there are a method of detecting the maximum amplitude in the entire spectrum, and a method of taking an average value with the spectrum amplitude of the surrounding frequencies and selecting a frequency that shifts from an increasing tendency to a decreasing tendency.

  When the peak amplitude value is detected, the threshold value setting unit 203 determines a threshold value used for determination of the no-signal area (step S108). The threshold setting unit 203 determines this threshold by obtaining a value obtained by multiplying the detected peak amplitude value by a threshold setting constant. At this time, as the maximum value of the spectrum amplitude used as a reference, an average value with the surrounding spectrum amplitude can be used in order to reduce the influence of noise.

  When the threshold is determined, the threshold determination / replacement unit 204 performs threshold determination / replacement processing (step S110). That is, the threshold determination / replacement unit 204 determines whether or not the spectrum amplitude value of the spectrum obtained in step S104 is smaller than the threshold determined by the threshold setting unit 203, and the spectrum amplitude value is less than the threshold. (Step S110-YES), it is determined that there is no signal at that frequency, and the spectrum value is replaced with a code representing no signal (Step S112).

  On the other hand, when the spectrum amplitude value is greater than or equal to the threshold (step S110-NO), the threshold determination / replacement unit 204 determines that a signal is present at that frequency, and the spectrum value maintains the original value. The code replaced by the threshold determination / replacement unit 204 is a code that can be discriminated from the value of another signaled area and is suitable for information compression described later. For example, all bits 0 and all bits 1 can be used as a code representing no signal. Regarding the comparison with the threshold value, an average value with the surrounding spectral amplitude can be used to reduce the influence of noise. Even if the spectrum amplitude is above the threshold, if the surrounding spectrum amplitude is below the threshold, it can be regarded as the influence of noise and replaced therewith to increase the efficiency of compression described later.

  The threshold determination / replacement unit 204 determines whether or not the threshold determination for all amplitude values has ended. If the threshold determination for all amplitude values has not ended (NO in step S114), the process proceeds to step S110. A threshold value determination process for the spectrum amplitude value and a spectrum value replacement process (step S112) are performed.

  On the other hand, when the threshold determination for all amplitude values is completed (YES in step S114), the information compression unit 205 performs information compression processing on the spectrum for which threshold determination / replacement processing has been performed (step S116). Here, the information compression unit 205 performs universal encoding such as differential encoding compression, run length compression, compression using an integer encoding such as an alpha code or a gamma code, regarding a spectrum value as an integer, entropy compression, lexicographic compression, and the like. Compression algorithms such as compression using encoding and compression using linear predictive encoding can be used. As a compression algorithm, it is also possible to perform continuous length compression on a spectrum determined to be no signal by outputting a code indicating no signal in the in-phase component of the spectrum and a number of consecutive non-signal regions instead of a quadrature component. it can. When the information compression process ends, the information compression unit 205 outputs the compressed spectrum value data. As a result, the compressed data is transmitted to the signal processing unit 104 via the network 103 from the multiband wireless transceiver 102 in which the information compression apparatus 200 is mounted.

  According to the embodiment described above, a signal equal to or less than the threshold value is determined as no signal from the amplitude value of the frequency spectrum of the received signal. The threshold value used here is set as a relative value obtained by multiplying the maximum value of the spectrum amplitude value by a fixed ratio, or a fixed value, so the set value depends on the center frequency, transmission speed, modulation method, and noise power of the signal. Do not depend. In this way, by setting an appropriate no-signal region determination threshold and cutting only spectrum information in a band where the amplitude value of the frequency spectrum is small, the transmission signal can be compressed without deterioration of the BER characteristics.

<< Second Embodiment >>
Next, a second embodiment will be described.
FIG. 4 is a block diagram illustrating functions of the information compression apparatus 300 according to the second embodiment. The time / frequency conversion unit 301, the peak spectrum amplitude value measurement unit 302, and the information compression unit 307 are respectively the time / frequency conversion unit 201, the peak spectrum amplitude value measurement unit 202, and the information compression unit 205 in the first embodiment. It corresponds and has the same function as the first embodiment.

  The noise spectrum amplitude value measuring unit 303 measures the spectrum amplitude value in a range not including the peak value of the spectrum amplitude value, and measures the spectrum amplitude value of the noise spectrum that is a no signal. The noise level intersection frequency measurement unit 304 measures the frequency at which the spectrum amplitude value of the frequency spectrum peaks and the frequency at which the spectrum amplitude value intersects the noise level.

  The signal band estimation unit 305 estimates a signal band that is a signal based on the peak amplitude value and peak frequency of the frequency spectrum, the noise frequency spectrum amplitude value, and the frequency measurement value. The no-signal band amplitude value replacement unit 306 converts the spectrum amplitude value within the signal band estimated by the signal band estimation unit 305 into the original value signal (signal), and the spectrum amplitude value outside the signal band. Are no signals and encode these signals.

Next, the operation of the information compression apparatus 300 in the configuration of FIG. 4 will be described.
FIG. 5 is a flowchart for explaining the operation of the information compression apparatus 300.
Here, as in the first embodiment described above, the time / frequency conversion unit 301 obtains a received signal including signals in a plurality of different bands (step S202), performs time / frequency conversion, and converts it into a frequency spectrum. (Step S204).

When the time / frequency conversion process is performed, the peak spectrum amplitude value measuring unit 302 obtains the spectrum amplitude value from the in-phase component and the quadrature component of the frequency spectrum, and detects the peak amplitude value (step S206). As the peak amplitude value detection method, the same method as in the first embodiment can be used.
When the time / frequency conversion process is performed, the noise spectrum amplitude value measurement unit 303 measures the noise spectrum amplitude value for the frequency spectrum obtained from the time / frequency conversion unit 301 (step S208). The noise spectrum amplitude value is measured by taking an average value of the spectrum amplitude value of the surrounding frequency and searching for a frequency where the average value does not change at the surrounding frequency, or a spectrum in a band where there is no peak having a large amplitude value. A method of measuring an average value of amplitude values can be used.

  When the measurement of the noise spectrum amplitude value is performed, the noise level intersection frequency measurement unit 304 outputs the noise spectrum amplitude from which the spectrum amplitude value is output from the noise spectrum amplitude value measurement unit 303 around the frequency that gives the peak amplitude value of the spectrum. Noise level intersection frequency measurement below the measured value is performed (step S210). The noise level intersection frequency is measured by measuring the frequency spectrum amplitude values on the high frequency side and the low frequency side from the frequency close to the frequency that is the peak amplitude value of the spectrum, and first the frequency that the spectrum amplitude value falls below the noise level. To do. As the amplitude value to be compared with the noise level, an average value with the surrounding spectrum amplitude can be used in order to reduce the influence of noise.

Next, the signal band estimation unit 305 includes the peak amplitude value A _peak obtained from the peak spectrum amplitude value measurement unit 302, the frequency f _peak that becomes the peak amplitude value, and the noise spectrum amplitude value obtained from the noise spectrum amplitude value measurement unit 303. A _noise , signal level band estimation processing is performed using the noise level intersection frequency (high frequency side f _{noise_u} , low frequency side f _{noise_l} ) obtained from the noise level intersection frequency measurement unit 304 (step S212).
In the signal band estimation, the zero crossing frequency at which the spectrum amplitude value of the signal is 0 is estimated from the above measured values for the high frequency side (f _{zero_u} ) and the low frequency side (f _{zero_l} ), and the band between these frequencies is Estimated to be a signaled band. For the zero crossing frequency estimation, an amplitude value of a frequency between the frequency that becomes the peak amplitude value and the noise level crossing frequency can be added and used. For the zero intersection frequency estimation, straight line estimation, polynomial estimation, function estimation, or the like can be used.

  In the case of straight line estimation, it is obtained from the following mathematical formula.

  Here, α is a value for setting an estimated value of the signaled band. α can be a constant value or can be set adaptively. Setting α to be larger than 1 can prevent the spectrum from being excessively shaved. Conversely, by setting α to be smaller than 1, it is possible to reduce the estimated bandwidth that is unnecessarily widened.

  The no-signal band amplitude value replacement unit 306 performs the amplitude value replacement process on the spectrum amplitude value of the band determined to be a signal by the signaled band estimation process (step S214). Here, the original values are maintained for the spectrum amplitude values in the signaled band, and the spectrum amplitude values other than the signaled band are set to no signal, and these signals are encoded. Here, the signal within the signal band is encoded according to the original value, and is encoded into a value representing no signal outside the signal band. When the amplitude value replacement process is performed, the information compression unit 307 performs the information compression process on the signal subjected to the amplitude value replacement process (step S216), and the spectral value data compressed by the information compression process Is output (step S218). A method similar to that of the first embodiment can be used for the amplitude value replacement process and the information compression process.

  According to the second embodiment described above, the frequency bandwidth of the signal is estimated from the peak of the amplitude value of the frequency spectrum of the received signal, the value of the noise spectrum, and the frequency that intersects the noise level. A frequency not included in the estimated bandwidth is determined as a no-signal band. Since this band estimation uses only the amplitude value of the spectrum, it does not depend on the center frequency of the signal, the transmission rate, and the modulation method. As a result, when transmitting the reception signal of the multi-band wireless transceiver to the signal processing unit at the subsequent stage, the no-signal band is estimated without information on the center frequency and bandwidth of the received signal, and the no-signal determination threshold is set sufficiently low In this case, the transmission signal can be compressed without BER degradation.

Next, the result of the numerical simulation in the above-described embodiment will be described below.
FIG. 6 is a diagram illustrating simulation conditions used for the simulation model which is the configuration of the information compression apparatus 200 in the first embodiment illustrated in FIG. In FIG. 6, the characteristics of the received signal bit error rate (BER) and the compression ratio (Compression ratio) with respect to the received signal-to-noise power ratio (SNR) were obtained as simulation conditions. Here, the compression rate is a value obtained by dividing the amount of data after compression by the amount of data before compression.

As the information compression algorithm, run length coding for transmitting a code representing the number of continuous spectrums and performing spectrum replacement was used.
As a conventional technique to be compared, characteristics when using an ideal rectangular bandpass filter (BPF) matched to the center frequency and frequency bandwidth of the received signal are also shown.

  FIG. 7 is a diagram showing the relationship between the received SNR and the BER. The value of the no-signal determination threshold is expressed by an attenuation amount from the peak spectrum amplitude value. When the no-signal determination threshold is set below 15 dB of the peak spectrum amplitude value, a BER equivalent to that when compression is not used can be obtained.

  FIG. 8 shows the received SNR and the signal compression effect when the first embodiment is applied. The compression effect is obtained from a value that is about 10 dB lower than the value expressed in dB for the attenuation from the peak spectrum amplitude of the no signal determination threshold, and if the SNR is sufficiently large, the presence of the signal in the received signal band The amount of transmission can be compressed to the same extent as the bandwidth ratio.

  According to the above-described embodiment, when the received signal of the information compression apparatus 200 is transmitted to the signal processing unit at the subsequent stage, the no-signal band is estimated without the information on the center frequency and bandwidth of the received signal, and the no-signal determination threshold is sufficient. When set low, the transmission signal can be compressed without BER degradation.

Next, the result of the numerical simulation in the above-described embodiment will be described below.
Here, the characteristics of the BER and the compression ratio with respect to the received SNR when the simulation conditions of FIG. 6 are applied to the simulation model that is the configuration of the information compression apparatus 300 in the second embodiment shown in FIG.

  FIG. 9 is a diagram showing the relationship between the received SNR and the BER in the second embodiment. When α is set to 0.7 or higher, a BER equivalent to that of an ideal BPF can be obtained when the SNR is 3 dB or higher. When the SNR is less than 3 dB, the BER deteriorates. However, by setting α to a large value, a margin for the frequency band to be transmitted is secured, and deterioration of the characteristics can be suppressed by preventing excessive spectrum cutting.

  FIG. 10 shows the received SNR and the signal compression effect when the above-described second embodiment is applied. When α is set to 0.7, if the SNR is high, the data amount can be compressed to about 1.4 times the ideal BPF ratio. When α = 1.0, the compression effect can be obtained up to a data amount of about 2.0 times the ideal BPF. When α = 2.0, the margin is large, so the data amount is 4.0 times the ideal BPF, and the compression effect is reduced.

FIG. 11 is a diagram for explaining the outline of signal processing in the first and second embodiments.
FIG. 11A is a diagram illustrating a time waveform of a reception signal input to the time / frequency conversion unit 201 of the reception signal. FIG. 11B is a diagram illustrating a waveform of a frequency spectrum obtained by performing time / frequency conversion processing on the reception signal of FIG. FIG. 11C is a diagram illustrating a frequency spectrum after replacing the spectrum of the no-signal band with the no-signal band with respect to the frequency spectrum of the reception signal illustrated in FIG. As shown in FIG. 11, the multiband radio transceivers according to the first and second embodiments determine that a signal equal to or less than a threshold value is a no-signal from the amplitude value of the frequency spectrum of the received signal.

  FIG. 12 is a diagram showing waveforms when the no-signal determination method in the first embodiment described above is performed. In this figure, when a peak amplitude value is detected by the peak spectrum amplitude value measuring unit 202, this detected value is obtained (symbol a). The threshold setting unit 203 multiplies the obtained value by a threshold setting constant to calculate a threshold used for no signal determination. As the calculated threshold value, for example, a value between a peak amplitude value and an amplitude value regarded as no signal is obtained. This value is determined as a threshold used in the threshold determination / replacement unit 204 (reference symbol b).

FIG. 13 is a diagram showing waveforms when the no-signal determination method according to the second embodiment of the present invention is performed.
In this figure, when a peak amplitude value is detected by the peak spectrum amplitude value measuring unit 302, the detected value is obtained (reference a). After the noise spectrum amplitude value is measured by the noise spectrum amplitude value measuring unit 303, the noise level intersection frequency measuring unit 304 performs noise level intersection frequency measurement around the frequency giving the peak amplitude value of the spectrum, and the spectrum The frequency spectrum amplitude values on the high frequency side (symbol b) and the low frequency side (symbol c) are measured from the frequency close to the frequency that becomes the peak amplitude value of the first, and the frequency whose spectrum amplitude value is lower than the noise level is obtained first .

  Further, by recording a program for realizing the functions of the information compression apparatuses 200 and 300 in FIG. 1 on a computer-readable recording medium, causing the computer system to read and execute the program recorded on the recording medium. Signal compression processing may be performed. Here, the “computer system” includes an OS and hardware such as peripheral devices.

Further, the “computer system” includes a homepage providing environment (or display environment) if a WWW system is used.
The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” dynamically holds a program for a short time like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory in a computer system serving as a server or a client in that case, and a program that holds a program for a certain period of time are also included. The program may be a program for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes designs and the like that do not depart from the gist of the present invention.

101A wireless communication system A wireless device 101B wireless communication system B wireless device 101C wireless communication system C wireless device 102 multi-band wireless transceiver 103 network 104 signal processing unit 200, 300 information compression device 201, 301 time / frequency conversion unit 202, 302 Peak spectrum amplitude value measurement unit 203 Threshold setting unit 204 Threshold determination / replacement unit 205, 307 Information compression unit 303 Noise spectrum amplitude value measurement unit 304 Noise level intersection frequency measurement unit 305 Signaled band estimation unit 306 No signal frequency band amplitude value replacement Part

Claims (2)

A time / frequency converter that obtains a frequency spectrum of the received signal by performing time / frequency conversion of the received signal on the received signal obtained by receiving signals transmitted from a plurality of wireless systems that use different frequencies;
Based on the spectrum amplitude value of the frequency spectrum, it is determined whether or not there is no signal, and a signal in a band determined to be no signal is replaced with a no-signal frequency band determination unit,
An information compression unit for compressing the signal from the no-signal frequency band determination unit;
A peak spectrum amplitude value measuring unit for measuring a spectrum amplitude value of a frequency spectrum obtained from the time / frequency converting unit and obtaining a peak value of the spectrum amplitude value;
A noise spectrum amplitude value measurement unit that obtains a noise spectrum amplitude value by measuring a spectrum amplitude value in a range not including the peak value of the spectrum amplitude value;
Measure the frequency spectrum amplitude value on the high frequency side and the low frequency side from the frequency at which the spectrum amplitude value of the frequency spectrum peaks, and measure the frequency at which the measured spectrum amplitude value is below the noise level An intersection frequency measurement unit;
Based on the peak value of the frequency spectrum and the peak frequency, the noise spectrum amplitude value, the frequency measurement value on the high frequency side, and the frequency measurement value on the low frequency side, the frequency measurement value on the high frequency side, and A signal band estimation unit that estimates a band between the frequency estimation value on the low frequency side as a signal band of a signal, and
The no-signal frequency band determination unit keeps the original value for the spectrum amplitude value in the signal band estimated by the signal-band estimation unit, and sets the spectrum amplitude value outside the signal band to no signal. Do
Information compression device comprising a call. The time / frequency converter of the computer
Obtain the frequency spectrum of the received signal by performing time / frequency conversion of the received signal on the received signal obtained by receiving signals transmitted from multiple wireless systems that use different frequencies,
The peak spectrum amplitude measurement part of the computer
Measure the spectrum amplitude value of the frequency spectrum obtained from the time-frequency conversion unit, obtain the peak value of the spectrum amplitude value,
The noise spectrum amplitude measurement part of the computer
Measurement of the spectrum amplitude value in a range not including the peak value of the spectrum amplitude value to obtain a noise spectrum amplitude value,
The noise level intersection frequency measurement part of the computer
Measure the frequency spectrum amplitude value on each of the high frequency side and the low frequency side from the frequency at which the spectrum amplitude value of the frequency spectrum peaks, and measure the frequency at which the measured spectrum amplitude value is below the noise level,
The signal bandwidth estimation part of the computer
Based on the peak value of the frequency spectrum and the peak frequency, the noise spectrum amplitude value, the frequency measurement value on the high frequency side, and the frequency measurement value on the low frequency side, the frequency measurement value on the high frequency side, and Estimating the band between the frequency estimation value on the low frequency side as a signal band of a signal,
The no-signal frequency band determination unit of the computer
Based on the spectrum amplitude value of the frequency spectrum, it is determined whether or not there is no signal, the signal of the band determined to be no signal is replaced with no signal,
The information compression part of the computer
An information compression method comprising compressing a signal from the no-signal frequency band determination unit.

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