JP2006245972A - Transmission signal analyzer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmission signal analyzer capable of setting a pilot signal at a user side when analyzing a transmission signal of wireless communication, and analyzing the transmission signal of wireless communication without providing an analyzer for each system. <P>SOLUTION: In the transmission signal analyzer, a pilot signal is inserted into an input signal, a transmission signal of an OFDM system transmitted from a transmitting unit is received by a receiving unit, a pilot signal is extracted and compared with the pilot signal inserted in transmission, and a transmission/reception signal is analyzed. The transmission signal analyzing device comprises a pilot signal setting means which sets a parameter of a pilot signal. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an apparatus for analyzing a transmission signal of wireless communication using a communication method in which a known signal is inserted into transmission data and amplitude / phase fluctuation compensation is performed based on the known signal.

  In recent years, in digital mobile radio communication systems such as wireless LAN (Local Area Network) and land mobile communication, multiple values that require synchronous detection such as 16 QAM (Quadrature Amplitude Modulation) and 64 QAM in order to improve transmission speed. A quadrature amplitude modulation method is applied.

  A modulation method called orthogonal frequency division multiplexing (OFDM) provides a number of orthogonal subcarriers (subcarriers) in a transmission band, assigns data to the amplitude and phase of each subcarrier, and PSK. (Phase Shift Keying) and digital modulation by QAM.

  Since this OFDM scheme divides the transmission band by a large number of subcarriers, the band per subcarrier is narrowed and the modulation speed is slow, but the total transmission speed is the same as the conventional modulation system. There is.

  In the OFDM method, since data is allocated to a plurality of subcarriers, an IFFT (Inverse Fast Fourier Transform) arithmetic circuit that performs inverse Fourier transform during modulation, and an FFT (Fast Fourier Transform) that performs Fourier transform during demodulation. ) There is a feature that a transmission / reception circuit can be configured by using an arithmetic circuit. Note that an OFDM transmission / reception apparatus is disclosed in Patent Document 1, Patent Document 2, and the like.

  In digital mobile radio communication involving movement of a transmission / reception station and movement of the surrounding environment, characteristics are greatly degraded due to fading in which the amplitude and phase of a received signal fluctuate. Therefore, for example, in order to apply QAM to mobile radio communication, an effective guarantee method for amplitude and phase fluctuations of a received signal due to fading is necessary.

  For this reason, in mobile radio communication, a known signal called a pilot signal is periodically inserted between information symbols on the transmission side, and the amplitude on the reception side is based on the pilot signal received from the transmission side in the complex baseband.・ A method that compensates by estimating the phase fluctuation is adopted. As a result, the receiving side can accurately estimate the impulse response of propagation in real time. Such a communication method is described in Non-Patent Document 1, for example.

JP 2001-313627 A JP 2002-217860 A Published by Shuichi Tsujioka, Chapter 5 of “Mobile Communications”, Ohm Publishing House, May 25, 1998 First edition, first edition

  Next, a configuration of a general transceiver according to the OFDM system will be described with reference to FIG. FIG. 7A is a configuration diagram of the transmission unit. In FIG. 7A, the input data is subjected to digital modulation mapping by the mapping unit 11. The data after the digital modulation mapping is arranged in parallel by an S / P (Serial / Parallel) conversion unit 12 and a pilot signal preset by a standard or the like is inserted by a pilot signal insertion unit 13.

  The mapped data into which the pilot signal is inserted is subjected to an inverse fast Fourier transform in an IFFT (Inverse Fast Fourier Transform) unit 14 to become an OFDM modulated signal. After that, the GI (guard interval) adding unit 15 and the preamble adding unit 16 add the GI and preamble to generate an output signal.

  The signal format of the modulated OFDM signal will be described with reference to FIG. FIG. 8 shows the subcarriers modulated in the time and frequency domains as square portions. In FIG. 8, there are N subcarriers, and ΔFs is called a subcarrier interval. A set {Sn, i | n = 1... N} of the signals Sn, i having the time i-th time width Ts in the n-th subcarrier is called a symbol.

  FIG. 9 shows an example of the waveform of the OFDM signal from the transmission side, and an output OFDM signal waveform is obtained by superimposing parallel signals from the first subcarrier to the Nth subcarrier.

  FIG. 1A is a block diagram of a receiving unit. A signal received by a receiver is symbol-synchronized by a symbol synchronizing unit 21, GI is removed by a GI removing unit 22, and an FFT (Fast Fourier Transform) unit 23 is used. Perform fast Fourier transform. Then, the phase rotation, the amplitude attenuation, and the like are obtained by comparing the phase / amplitude value change of the pilot signal added on the transmission side by the compensation unit 24 with the same known pilot signal as that on the transmitter side. From these, an estimated value of correction for each carrier is calculated.

  Carrier correction is performed using the obtained correction value, P / S conversion is performed by a P / S (Parallel / Serial) conversion unit 25, and digital modulation demapping unit 26 and demapping unit 27 perform digital modulation demodulation. Demodulated data is obtained after mapping.

  When analyzing a transmission signal of wireless communication using a communication method that performs amplitude / phase variation compensation based on a pilot signal, the analysis device functions as a device on the receiving side.

  The operation of the transmission signal analysis is shown in the flowchart of FIG. After symbol synchronization of the OFDM signal in step 10A, GI is removed in step 10B, FFT is performed in step 10C, a pilot signal is extracted from the fixed pilot signal position for each standard in step 10D, and the pilot signal is extracted in steps 10E and 10F. Is used to correct the RF offset and the baseband offset, and in step 10G, the phase and amplitude of each carrier using the pilot signal are corrected. In step 10H, the pilot signal inserted on the transmission side is corrected. Are compared with the pilot signal on the receiving side for analysis.

  The pilot signal to be inserted is fixedly determined for each system based on standards such as wireless LAN IEEE802.11g, 11a, ISDB-T. For example, a pilot signal is inserted horizontally as shown in FIG. 11A, a pilot signal is inserted vertically as shown in FIG. 11A, or FIG. The pilot signal inserted for each standard is determined such that the pilot signal is inserted at specific intervals as shown in FIG.

  Since the analysis device corresponding to the pilot signal is used when analyzing the transmission signal, the user needs to prepare a device for analyzing the transmission signal of the wireless communication for each system.

  The present invention provides a transmission signal analyzing apparatus that enables a user to set a pilot signal when analyzing a wireless communication transmission signal, and can analyze the wireless communication transmission signal without providing an analysis apparatus for each system. The purpose is to do.

  In order to achieve such a problem, the invention according to claim 1 is characterized in that a pilot signal is inserted into an input signal, an OFDM transmission signal transmitted from a transmitter is received by a receiver, and a pilot signal is received. The transmission signal analyzing apparatus for extracting and comparing with the pilot signal inserted at the time of transmission and analyzing the transmitted / received signal includes pilot signal setting means for setting parameters of the pilot signal.

  According to a second aspect of the present invention, in the first aspect of the present invention, the pilot signal setting means expands the signal format of the OFDM signal into matrix data, and a pilot signal for each data in the matrix. Set the parameters.

The invention according to claim 3 is the invention according to claim 1 or 2,
The pilot signal setting means includes a mapping unit for mapping an input signal, an output of the mapping unit as an input, an S / P converter for serial-parallel conversion of the input signal, and a pilot signal as an output of the S / P converter A pilot signal insertion unit that inserts a signal, an output of the S / P converter into which the pilot signal is inserted are input, an IFFT unit that performs inverse fast Fourier transform, and an output of the IFFT unit is input, and a guard interval is added. Of the transmission unit including a guard interval addition unit and a preamble addition unit that receives the output of the guard interval addition unit and adds a preamble and outputs a transmission signal, the pilot signal insertion unit.

  According to a fourth aspect of the present invention, in the first or second aspect of the present invention, the pilot signal setting means inputs a symbol synchronization unit that performs symbol synchronization of an input signal and an output of the symbol synchronization unit. A guard interval removing unit that removes a guard interval; an FFT unit that receives the output of the guard interval removing unit as input; a fast Fourier transform; a pilot signal setting unit that sets a pilot signal; an output of the FFT unit and the pilot An output of the signal setting unit is input, a compensation unit that compensates data based on a pilot signal of the pilot signal setting unit, a P / S conversion unit that receives the output of the compensation unit and performs parallel-serial conversion, and the P / A digital modulation demapping unit that receives the output of the S conversion unit and performs digital modulation demapping; Tone de the mapping of the input and output, of the receiving part comprising a demapper for demapping a pilot signal setting section.

  According to a fifth aspect of the present invention, in the third aspect of the invention, the pilot signal insertion unit includes a first setting unit, a first pilot signal generation unit, and a first control unit.

  According to a sixth aspect of the present invention, in the fourth aspect of the present invention, the pilot signal setting unit includes a second setting unit, a second pilot signal generation unit, and a second control unit.

  The invention according to claim 7 is the invention according to claim 4 or claim 5, wherein the first and second setting units are any one of an insertion position, an amplitude, a phase value, and a power value of a pilot signal, or Set everything.

According to the present invention, it is possible to set a pilot signal to be inserted into a transmission / reception signal. Specifically, the pilot signal temporal and frequency extraction positions, amplitude values, phase values, power values, and the like can be set. Thereby, even when the standard of the transmitter / receiver to be analyzed is different, the transmission characteristic can be analyzed by setting a pilot signal according to the standard, and it is not necessary to prepare an analysis device for each different standard.
Further, since the signal format of the OFDM signal is directly taken in as matrix data to form matrix data, it is easy to understand visually and can be easily performed even when setting input is performed.

  The transmission signal analyzing apparatus according to the present invention will be described below. FIG. 1 is a block diagram showing an embodiment of the present invention. In addition, the same code | symbol is attached | subjected about the same thing as FIG. 7 which is a structural example of a prior art, and description is abbreviate | omitted.

  FIG. 1 shows a configuration in which a pilot signal setting unit 1 is provided for the compensation unit 24 in the receiving unit of FIG. The pilot signal setting unit 1 includes a setting unit 1A, a pilot signal generation unit 1B, and a control unit 1C.

  The signal format of the OFDM signal is as shown in FIG. 8, and is visually a matrix. The setting unit 1A processes the subcarrier group indicated by the square portion in FIG. 8 as a matrix, and takes in the pilot signal set in the pilot signal insertion unit 13 of the transmission unit in FIG. 7A as a pilot signal matrix. Based on this pilot signal matrix data, the phase value, amplitude value, and power value of the pilot signal according to the standard are set for each cell of the matrix. Alternatively, a known pilot signal is input and set by external input means (not shown).

  The installation unit IA includes display means for displaying the captured pilot signal matrix as matrix data.

  The pilot signal generation unit 1B generates a pilot signal based on the pilot signal information set by the setting unit 1A. The control unit 1 </ b> C controls the input / output of the setting unit 1 </ b> A and the display unit (not shown) and sets the generated pilot signal in the compensation unit 24. It is also used for analysis of received signals.

  Next, the generation state of the pilot signal matrix will be described with reference to FIG. 2, and the created pilot signal matrix is shown in FIG. In FIG. 2, when the pilot signal inserted into the OFDM signal is as shown in (a), the setting unit 1A in FIG. 1 replaces the information in FIG. 2 (a) with a matrix and extracts necessary data. The configuration is as shown in FIG.

  In FIG. 2A, the first row is information on the time position of the pilot signal, the first column is information on the extracted carrier position of the pilot signal, 1 in the first row and first column, and 0 in the first row and second column. Is entered. In the second column, the carrier phase constant flag is input, and in the others, the phase and amplitude value at each time and carrier position are input. When 1 is input after the second row and the second column of the pilot setting matrix, all the phases can be treated as being constant in the input carrier number on the left side. As the phase / amplitude value of the pilot signal, a real number or an imaginary number is input at the time and frequency positions to be extracted.

  The matrix created in this way is as shown in FIG. In the examples of FIGS. 2 and 3, the pilot signal power is 1 and the phase is 0 and π.

  Next, the operation of the pilot signal setting unit 1 of FIG. 1 will be described with reference to the flowchart of FIG. First, in step 4A, the setting unit 1A of the pilot signal setting unit 1 reads a matrix for setting pilot signals. Since the relationship between the time position and the carrier position is known from the read matrix, the carrier position of the pilot signal to be extracted at a certain time is determined in step 4B. For example, in the case of FIG. 2A, the carrier positions are “2” and “5” at time “1-6”.

  Similarly, since the relationship between the time position and the pilot phase information is known, in step 4C, the prescribed phase value and power value of the pilot signal at a certain time are determined. For example, in the case of FIG. 2A, the power is all “1” at the pilot phase value of time “1-6”. The specified phase value and power value are used for correction. In step 4D, the value of the pilot signal is extracted from the determined carrier position. The extracted pilot signal becomes a known signal in the compensator 24, and is compared with this to obtain phase rotation, amplitude attenuation, and the like of the received signal.

  As described above, the same pilot signal as that on the transmission side can be applied to the compensation unit on the reception side by extracting the pilot signal from the transmission side or setting the pilot signal with an external input unit (not shown). it can.

  Since the pilot signal is inserted at the time of generating the OFDM signal on the transmission side, it is possible to set the pilot signal on the transmission side. In other words, information such as the pilot signal insertion position, amplitude value, and phase value is required when the pilot signal is inserted. Therefore, by using a matrix having the same configuration as that of the receiving unit that performs the analysis operation, it is possible to insert these parameters at the determined pilot signal positions.

  FIG. 5 is a configuration diagram of a transmission unit provided with a pilot signal insertion unit 2 including a pilot signal setting unit 2A and a pilot signal generation unit 2B in place of the pilot signal insertion unit 13 having the configuration of FIG. The setting unit 2A of the pilot signal inserting unit 2 is similar to the configuration of the pilot signal setting unit 1 of the receiving unit, and performs setting of the pilot signal by external input means (not shown).

  In FIG. 2A, the case where the pilot signal power is 1 and the phase is 0 and π is described as an example. However, the case where the pilot signal signal power is other than 1 and the phase is other than 0 and π can also be handled. it can. Specifically, when changing the input power, the input value is changed. The phase can be changed to other than π by using an imaginary number. FIG. 6 is a usage example using imaginary numbers, and is an example when the phase is ± π / 4 and ± 3π / 4 and the pilot signal power is √2. The larger the value of the pilot signal power, the better the accuracy of the estimated values of amplitude and attenuation.

It is an example of a structure of the receiving part to which this invention is applied. It is explanatory drawing which shows the production | generation state of a pilot signal matrix. It is an example of the produced | generated matrix. 4 is a flowchart for explaining the operation of a pilot signal setting unit 1. It is an example of a structure of the transmission part to which this invention is applied. It is explanatory drawing which shows the production | generation state of the pilot signal matrix which uses an imaginary number. It is a structural example of the transmission part by a prior art, and a receiving part. It is an example of the signal format of the modulated OFDM signal. It is an example of the waveform of the OFDM signal from the transmission side. It is a flowchart explaining the operation | movement which analyzes a transmission signal. It is an example which shows the state by which the pilot signal was inserted.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pilot signal setting part 1A Setting part 1B Pilot signal generation part 1C Control part 2 Pilot signal insertion part 2A Setting part 2B Pilot signal generation part

Claims (7)

The pilot signal is inserted into the input signal, the OFDM transmission signal transmitted from the transmitter is received by the receiver, the pilot signal is extracted, compared with the pilot signal inserted at the time of transmission, and the transmission / reception signal is In the transmission signal analyzer to analyze,
A transmission signal analyzing apparatus comprising pilot signal setting means for setting parameters of a pilot signal.   2. The transmission signal analysis according to claim 1, wherein the pilot signal setting means expands the signal format of the OFDM signal into matrix data, and sets the pilot signal parameters for each data in the matrix. apparatus. The pilot signal setting means includes
A mapping unit for mapping the input signal;
An S / P converter that receives the output of the mapping unit as an input and performs serial-parallel conversion of the input signal;
A pilot signal insertion unit that inserts a pilot signal into the output of the S / P conversion unit;
An IFFT unit that receives the output of the S / P converter into which the pilot signal is inserted as input and performs inverse fast Fourier transform;
A guard interval adding unit that receives the output of the IFFT unit and adds a guard interval;
3. The pilot signal insertion unit of the transmission unit including a preamble addition unit that receives the output of the guard interval addition unit as an input, adds a preamble, and outputs a transmission signal. Transmission signal analyzer. The pilot signal setting means includes
A symbol synchronization unit that performs symbol synchronization of the input signal;
A guard interval removing unit that receives the output of the symbol synchronization unit and removes the guard interval;
An FFT unit that receives the output of the guard interval removal unit as input and performs fast Fourier transform;
A pilot signal setting unit for setting a pilot signal;
A compensation unit that inputs an output of the FFT unit and an output of the pilot signal setting unit, and compensates data based on a pilot signal of the pilot signal setting unit;
A P / S converter that performs parallel-serial conversion using the output of the compensator as an input; and
A digital modulation demapping unit that receives the output of the P / S conversion unit and performs digital modulation demapping;
3. The transmission signal analyzing apparatus according to claim 1, wherein the transmission signal analyzing apparatus is a pilot signal setting unit among receiving units including an output of the digital modulation demapping unit and having a demapping unit for demapping.   4. The transmission signal analyzing apparatus according to claim 3, wherein the pilot signal insertion unit includes a first setting unit, a first pilot signal generation unit, and a first control unit.   5. The transmission signal analyzing apparatus according to claim 4, wherein the pilot signal setting unit includes a second setting unit, a second pilot signal generation unit, and a second control unit. 6. The transmission signal analyzing apparatus according to claim 4, wherein the first and second setting units set any or all of an insertion position, an amplitude, a phase value, and a power value of a pilot signal.

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