JP2010199814A - Communication device and communication quality estimation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication technology capable of estimating communication quality by simple processing. <P>SOLUTION: A signal point acquisition part 5 obtains a reception signal point on an IP plane for each of a training symbol and a pilot symbol received in a reception part 2. A correction acquisition part 6 obtains a correction amount for the reception signal point of the pilot symbol on the basis of the reception signal point for the training symbol and a known ideal signal point. A correction part 7 corrects the reception signal point of the pilot symbol on the basis of the correction amount obtained in the correction amount acquisition part 6. A communication quality estimation part 8 estimates communication quality on the basis of the corrected reception signal point for the pilot symbol and the known ideal signal point. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a communication apparatus for estimating communication quality based on a known signal and a method for estimating communication quality based on a known signal.

  Conventionally, various techniques relating to wireless communication have been proposed. For example, Patent Document 1 discloses a technique for obtaining SINR (Signal to Interference plus Noise Power Ratio) that is an index of communication quality. Non-Patent Document 1 describes a standard for the next generation PHS (Personal Handyphone System).

Japanese Patent Laid-Open No. 2004-72724

“ARIB STD-T95“ OFDMA / TDMA TDD Broadband Wireless Access System (Next Generation PHS) ARIB STANDARD ”Version 1.1”, June 6, 2008, Japan Radio Industry Association

  Now, in communication technology, it is generally desired that communication quality can be estimated with as simple a process as possible.

  Therefore, the present invention has been made in view of the above-described points, and an object thereof is to provide a communication technique capable of estimating communication quality by simple processing.

  In order to solve the above problems, a communication apparatus according to the present invention includes a receiving unit that receives first and second known signals, and an IQ plane for each of the first and second known signals received by the receiving unit. Based on the signal point acquisition unit for obtaining the received signal point above, the received signal point of the first known signal, and the known ideal signal point on the IQ plane for the first known signal, A correction amount obtaining unit for obtaining a correction amount for the received signal point of the two known signals, a correction unit for correcting the received signal point of the second known signal based on the correction amount, and the second known signal A communication quality estimator that estimates communication quality based on the received signal point after the correction and a known ideal signal point on the IQ plane for the second known signal.

  Moreover, in one aspect of the communication apparatus according to the present invention, the communication quality estimation unit is based on the received signal point after correction for the second known signal and the ideal signal point of the second known signal. The communication quality is estimated by obtaining EVM (Error Vector Magnitude) or SINR (Signal to Interference plus Noise Power Ratio).

  The communication quality estimation method according to the present invention includes (a) a step of receiving a first known signal, (b) a step of receiving a second known signal, and (c) received in step (a). A step of obtaining a reception signal point on the IQ plane for the first known signal; and (d) a step of obtaining a reception signal point on the IQ plane for the second known signal received in the step (b). And (e) the received signal point of the second known signal based on the received signal point of the first known signal and the known ideal signal point on the IQ plane for the first known signal. (F) correcting the received signal point of the second known signal based on the correction amount; and (g) correcting the received signal for the second known signal. A point and a known logic on the IQ plane for the second known signal. Based on a signal point, and a step of estimating the communication quality.

  According to the present invention, the received signal point of the second known signal is corrected based on the correction amount obtained based on the received signal point and the known ideal signal point for the first known signal, and the received signal after correction is corrected. Communication quality is estimated based on the point and the known ideal signal point of the second known signal. Therefore, the communication quality can be estimated without performing processing for obtaining bit data corresponding to the received signal point from the received signal point on the IQ plane for the received signal. Therefore, the communication quality can be estimated with a simple process. Furthermore, since the communication quality can be estimated using only the known signal, the communication quality can be estimated even when the data signal is not transmitted in a certain time zone.

It is a figure which shows the structure of the communication apparatus which concerns on embodiment of this invention. It is a figure which shows the structural example of PRU of next generation PHS. It is a flowchart which shows operation | movement of the communication apparatus which concerns on embodiment of this invention. It is a figure for demonstrating the process which calculates | requires the corrected amount in the communication apparatus which concerns on embodiment of this invention. It is a figure for demonstrating the primary correction | amendment with respect to the data symbol in the communication apparatus which concerns on embodiment of this invention. It is a figure for demonstrating the secondary correction | amendment with respect to the data symbol in the communication apparatus which concerns on embodiment of this invention. It is a figure for demonstrating the process which estimates the communication quality in the communication apparatus which concerns on embodiment of this invention.

  FIG. 1 is a diagram showing a configuration of a communication apparatus 100 according to an embodiment of the present invention. The communication device 100 is, for example, a base station that conforms to the next-generation PHS defined in Non-Patent Document 1 described above, and a plurality of communication terminals (not shown) with an OFDMA (Orthogonal Frequency Division Multiple Access) method. Two-way wireless communication is performed. The communication device 100 can simultaneously communicate with a plurality of communication terminals by individually allocating radio resources specified in two dimensions including a time axis and a frequency axis to each of the plurality of communication terminals. Yes.

  As illustrated in FIG. 1, the communication device 100 includes a wireless communication unit 1 having a reception unit 2 and a transmission unit 3, a signal point acquisition unit 5, a correction amount acquisition unit 6, a correction unit 7, and a communication quality estimation. A unit 8, a demodulation unit 9, a transmission data generation unit 10, and a modulation unit 11 are provided. The reception unit 2 and the transmission unit 3 share the transmission / reception antenna 4.

  The receiving unit 2 performs amplification processing and down-conversion on the signal received by the transmission / reception antenna 4, converts the signal received by the transmission / reception antenna 4 into a baseband signal, and outputs the baseband signal. In the present embodiment, a signal received by the transmission / reception antenna 4 is modulated by a BPSK (Binary Phase Shift Keying) modulation method, a QPSK (Quadrature Phase Shift Keying) modulation method, or the like.

  The signal point acquisition unit 5 acquires an I component (in-phase component) and a Q component (quadrature component) of each symbol included in the baseband signal output from the reception unit 2. Thus, the signal point acquisition unit 5 obtains a reception signal point on the IQ plane for each symbol included in the baseband signal. The baseband signal includes data symbols, known training symbols, and known pilot symbols, as will be described later.

  Based on the training symbol reception signal point obtained by the signal point acquisition unit 5, the correction amount acquisition unit 6 performs the primary correction amount for the data symbol reception signal point and the correction amount for the pilot symbol reception signal point. Ask for. Further, the correction amount obtaining unit 6 obtains a secondary correction amount for the received signal point of the data symbol based on the received signal point of the pilot symbol obtained by the signal point obtaining unit 5.

  The correction unit 7 corrects the reception signal point of the data symbol based on the primary correction amount obtained by the correction amount acquisition unit 6, and then the data based on the secondary correction amount obtained by the correction amount acquisition unit 6. The received signal point after correcting the symbol is corrected again. The correction unit 7 corrects the reception signal point of the pilot symbol based on the correction amount obtained by the correction amount acquisition unit 6.

  The communication quality estimation unit 8 estimates the communication quality between the communication device 100 and the communication counterpart device based on the reception signal point of the pilot symbol corrected by the correction unit 7.

  The demodulator 9 acquires bit data corresponding to the data symbol based on the reception signal point of the data symbol corrected in two stages by the correction unit 7. Thereafter, the demodulator 9 performs error correction processing or the like on the acquired bit data, and reproduces data transmitted from the communication partner apparatus.

  The transmission data generation unit 10 generates transmission data based on the data from the communication partner apparatus reproduced by the demodulation unit 9.

  Based on the communication quality estimated by the communication quality estimation unit 8, the modulation unit 11 determines the modulation method used when the transmission data generated by the transmission data generation unit 10 is transmitted. In the next generation PHS, a plurality of modulation schemes are defined, and the modulation unit 11 selects a modulation scheme according to the communication quality estimated by the communication quality estimation unit 8 from the plurality of modulation schemes. For example, the modulation unit 11 selects a BPSK modulation method with a low data transmission rate when the communication quality is poor, and selects a QPSK modulation method with a high data transmission rate when the communication quality is good. Then, modulation section 11 modulates a plurality of subcarriers with transmission data according to the determined modulation scheme. After that, the modulation unit 11 combines the plurality of modulated subcarriers to generate a baseband signal (baseband OFDM symbol). This baseband signal is input to the transmitter 3.

  The transmission unit 3 performs up-conversion and amplification processing on the input baseband signal, and then inputs the baseband signal to the transmission / reception antenna 4. Thereby, a radio signal is transmitted from the transmission / reception antenna 4 toward the communication partner apparatus.

  Here, in the next-generation PHS, communication between a base station and a communication terminal is performed in units of 200 PRU (Physical Resource Unit). For example, in the base station, radio resources are allocated to communication terminals in units of PRU 200, and a modulation scheme used when transmitting transmission data to the communication terminals is determined for each PRU 200. One PRU 200 is represented by one subchannel having a bandwidth of 900 kHz and one slot having a time width of 625 μs. One subchannel is composed of 24 subcarriers.

  FIG. 2 is a diagram illustrating a configuration example of the PRU 200. In FIG. 2, the horizontal direction and the vertical direction indicate time and frequency, respectively. S1 to S19 in FIG. 2 indicate OFDM symbol numbers, and F1 to F24 in FIG. 2 indicate subcarrier frequency numbers. The PRU 200 is expressed in two dimensions including a time axis and a frequency axis. As shown in FIG. 2, the PRU 200 includes, for example, a plurality of data symbols 201, a plurality of training symbols 202, a plurality of pilot symbols 203, and a plurality of null symbols 204. The PRU 200 is provided with a first guard time GT1 at the beginning and a second guard time GT2 at the end in the time axis direction. In the example of FIG. 2, each of the subcarriers of frequencies F2 to F12 and F14 to F24 included in the OFDM symbol S1 is a training symbol 202, and is included in each of the OFDM symbols S5, S9, S13, and S17. Each of subcarriers of frequencies F3, F7, F11, F15, F19, and F23 is a pilot symbol 203. The subcarrier of frequency F1 is a guard carrier, and the subcarrier of frequency F13 is a DC carrier. Each of the guard carrier and the DC carrier of the OFDM symbols S1 to S19 is a null symbol 204.

  Communication apparatus 100 according to the present embodiment reproduces received data from a communication partner apparatus and estimates communication quality with the communication partner apparatus in units of PRU 200. The reception data reproduction process and communication quality estimation process in the communication apparatus 100 will be described in detail below.

  FIG. 3 is a flowchart showing a series of operations of communication apparatus 100 according to the present embodiment until reception data reproduction processing and communication quality estimation processing are performed. As shown in FIG. 3, in step ST <b> 1, the signal point acquisition unit 5 receives the plurality of training symbols 202, the plurality of pilot symbols 203, and the plurality of data symbols 201 included in one PRU 200 received by the reception unit 2. A reception signal point on the IQ plane for each is obtained.

  Next, in step ST <b> 2, the correction amount acquisition unit 6 determines the correction amounts for the reception signal points of the plurality of pilot symbols 203 based on the reception signal points of the plurality of training symbols 202 acquired by the signal point acquisition unit 5. The primary correction amounts for the reception signal points of the plurality of data symbols 201 are obtained.

  Here, the reception signal point of each symbol received by the receiving unit 2 changes from the ideal signal point depending on the characteristics of the transmission path transmitted by the symbol. In step ST2, the training symbol 202 is used to obtain a correction amount for making the received signal points of the data symbol 201 and the pilot symbol 203 close to the ideal signal point. Note that the received signal point of the data symbol 201 is corrected in two stages so as to approach the ideal signal point. In step ST <b> 2, a primary correction amount that is a first-stage correction amount is obtained for each data symbol 201.

  FIG. 4 is a diagram for explaining the processing in step ST2. FIG. 4 shows a received signal point 300 on the IQ plane of a certain training symbol 202 when the signal received by the transmission / reception antenna 4 is modulated by the QPSK modulation method.

  Since the ideal signal point 301 on the IQ plane of each training symbol 202 included in the PRU 200 is known, with respect to each training symbol 202, how much the received signal point 300 has changed from the ideal signal point 301 due to the transmission path characteristics. Can be specified. And in one slot, the characteristics of the transmission path between the communication apparatus 100 and the communication partner apparatus do not change so much, so each of the data symbol 201 and the pilot symbol 203 received after the training symbol 202 The received signal point can be considered to change from the ideal signal point in the same manner as the received signal point 300 of the training symbol 202 having the same frequency.

  Therefore, in the present embodiment, for each training symbol 202, as shown in FIG. 4, a change amount 310 of the received signal point 300 necessary for matching the received signal point 300 with the ideal signal point 301 is obtained. Specifically, the amount of change in amplitude and the amount of phase rotation for the received signal point 300 necessary to make the received signal point 300 coincide with the ideal signal point 301 are obtained. Then, the amount of change 310 obtained for the training symbol 202 having the same frequency as the primary correction amount for each data symbol 201 is employed. The primary correction amount for each data symbol 201 obtained in this way can be regarded as an estimated value of the change amount of the received signal point necessary for matching the received signal point with the unknown ideal signal point. .

  Similarly, the amount of change 310 obtained for the training symbol 202 having the same frequency as that of the received signal point of each pilot symbol 203 is employed. The correction amount for each pilot symbol 203 obtained in this way can be regarded as an estimated value of the change amount of the received signal point necessary for matching the received signal point with the ideal signal point.

  Note that the amount of change 310 obtained for the training symbol 202 depends on the characteristics of the transmission path transmitted by the training symbol 202, and therefore, the amount of change 310 can be regarded as an estimated value of the transmission path characteristics.

  Next, in step ST3, the correction unit 7 corrects the reception signal point of each data symbol 201 based on the corresponding primary correction amount. Specifically, as illustrated in FIG. 5, the correction unit 7 sets the amplitude and phase of the reception signal point 400 of each data symbol 201 on the IQ plane by the corresponding primary correction amount (change amount 310). Change. Thereby, symbol distortion due to transmission path characteristics can be canceled, and the corrected received signal point 402 for each data symbol 201 can be brought closer to the ideal signal point 401.

  Similarly, the correction unit 7 corrects the reception signal point of each pilot symbol 203 based on the correction amount corresponding thereto. Specifically, the correction unit 7 changes the amplitude and phase of the reception signal point of each pilot symbol 203 on the IQ plane by a corresponding correction amount (change amount 310). Thereby, symbol distortion due to transmission path characteristics can be canceled, and the corrected received signal point for each pilot symbol 203 can be brought close to the ideal signal point.

  When step ST3 is executed in communication apparatus 100, steps ST4 and ST5 are executed. In step ST <b> 4, the correction amount acquisition unit 6 obtains a secondary correction amount for each data symbol 201 based on the reception signal points of a plurality of pilot symbols 203 included in the PRU 200.

  Here, even within one slot, the characteristics of the transmission path between the communication apparatus 100 and the communication partner apparatus slightly change. The training symbol 202 is included only in the first OFDM symbol S1 of the PRU 200, while the plurality of data symbols 201 are spread over the OFDM symbols S2 to S19 after the OFDM symbol S1 in the PRU 200. Included in them. Therefore, the characteristics of the transmission path when the data symbol 201 is received may greatly change from the characteristics of the transmission path when the training symbol 202 is received. Therefore, the difference between the reception signal point and the ideal signal point for the training symbol 202 and the difference between the reception signal point and the ideal signal point for the data symbol 201 having the same frequency as the training symbol 202 may be greatly different. Therefore, as described above, it is assumed that the received signal point at the data symbol 201 having the same frequency as the training symbol 202 is corrected using the change amount 310 (estimated value of the transmission path characteristic) obtained for the training symbol 202. However, symbol distortion due to transmission path characteristics cannot be sufficiently canceled, and the received signal point in the data symbol 201 may not be sufficiently close to the ideal signal point. As a result, there is a possibility that the bit data corresponding to the data symbol 201 cannot be accurately obtained from the reception signal point of the data symbol 201.

  On the other hand, since the ideal signal point on the IQ plane is known for pilot symbol 203, the correction amount for the received signal point of data symbol 201 is set using pilot symbol 203 in the same manner as training symbol 202. Can be sought. Also, as shown in FIG. 2, the plurality of pilot symbols 203 are included in the PRU 200 in a temporally distributed manner, unlike the training symbols 202, so that the communication apparatus 100 includes a plurality of data symbols 201. Most of them are received at a time closer to the pilot symbol 203 than to the training symbol 202. Therefore, for most data symbols 201, the transmission path characteristics at the time of reception are not so different from the transmission path characteristics at the time of reception of pilot symbol 203.

  Therefore, in the present embodiment, the secondary correction amount of the reception signal point of each data symbol 201 is obtained using reception signal points of a plurality of pilot symbols 203. Then, the reception signal point of each data symbol 201 is corrected again with the secondary correction amount. As a result, the influence of the temporal change in the transmission path characteristics can be canceled, and the reception signal point of each data symbol 201 can be brought closer to the ideal signal point.

  In step ST4, the correction amount acquisition unit 6 first obtains the amount of change of the received signal point necessary for matching the received signal point with the known ideal signal point for each pilot symbol 203, as in step ST2. Then, the correction amount acquisition unit 6 determines the amount of change in the received signal point necessary for matching the received signal point with the ideal signal point for each data symbol 201 based on the changed amount obtained for the plurality of pilot symbols 203. Get an estimate. That is, the correction amount estimation unit 6 obtains an estimated value of the characteristics of the transmission path transmitted by each data symbol 201. In the PRU 200, an estimated value of the change amount for the data symbol 201 between two adjacent pilot symbols 203 can be obtained using, for example, an interpolation method. Further, in the PRU 200, an estimated value of the change amount for the data symbol 201 located outside the plurality of pilot symbols 203 can be obtained by using, for example, an extrapolation method. Then, the correction amount acquisition unit 6 obtains a difference between the primary correction amount obtained in step ST2 and the estimated change amount obtained in step ST4 for each data symbol 201, and obtains the difference as the secondary correction amount. And

  Next, in step ST6, the correction unit 7 corrects the received signal point after the primary correction of each data symbol 201 obtained in step ST3 again based on the corresponding secondary correction amount. FIG. 6 is a diagram showing how the received signal point 402 after correction shown in FIG. 5 is corrected based on the secondary correction amount 410. As shown in FIG. 6, the received signal point 403 after the secondary correction is obtained by changing the amplitude and phase of the corrected received signal point 402 for the data symbol 201 on the IQ plane by the secondary correction amount 410. The ideal signal point 401 is closer than the reception signal point 402 after the primary correction.

  Thereafter, in step ST <b> 7, the demodulation unit 9 obtains bit data corresponding to each data symbol 201 based on the reception signal point after the secondary correction for each data symbol 201. In the example of FIG. 6, the signal point closest to the received signal point 403 after the secondary correction among the plurality of signal points respectively corresponding to the bit data “00”, “10”, “11”, “01” is “ Since the signal point corresponds to “00”, the bit data corresponding to the data symbol 201 is “00”. In this way, appropriate bit data corresponding to each data symbol 201 can be acquired. As a result, the communication device 100 can reproduce data received from the communication partner device.

  Further, in step ST5 executed after step ST3, the communication quality estimation unit 8 determines the communication quality between the communication apparatus 100 and the communication counterpart apparatus based on the corrected received signal point for each pilot symbol 203. presume.

  Here, as described above, the reception signal point of pilot symbol 203 is corrected in step ST3 so that the influence of the transmission path characteristic is canceled. Therefore, ideally, the reception signal point after correction is ideal. It will coincide with the signal point.

  However, since noise is added to the signal received by the transmission / reception antenna 4 in the transmission path, even if the reception signal point for the reception signal is corrected as described above, the corrected reception signal point is the ideal signal point. Does not match. Since the difference between the received signal point and the ideal signal point depends on the magnitude of noise added to the signal received by the transmission / reception antenna 4, it represents the quality of communication between the communication device 100 and the communication partner device. Can be considered.

  Therefore, in the present embodiment, the communication quality estimation unit 8 determines the communication quality between the communication apparatus 100 and its counterpart apparatus based on the difference between the corrected received signal point and the ideal signal point for the pilot symbol 203. presume. The communication quality estimation unit 8 estimates the communication quality by obtaining EVM (Error Vector Magnitude), for example. FIG. 7 is a diagram for explaining the processing in step ST5.

  As shown in FIG. 7, reception signal point 500 of pilot symbol 203 is corrected by the correction amount (change amount 310) obtained in step ST2 in step ST3. Then, a difference 510 corresponding to the communication quality is generated between the reception signal point 502 after the correction of the pilot symbol 203 and the ideal signal point 501. This difference 510 becomes the EVM of the pilot symbol 203. Since the ideal signal point 501 is known, the EVM of the pilot symbol 203 can be obtained based on the received signal point 502 and the ideal signal point 501 after correction. The communication quality estimation unit 8 obtains each EVM of the plurality of pilot symbols 203 in the PRU 200. And the communication quality estimation part 8 calculates | requires the average value of several calculated | required EVM, and makes the said average value EVM in PRU200 whole. The modulation unit 11 determines a modulation method to be used when transmitting transmission data based on the average value of EVM obtained by the communication quality estimation unit 8. For example, the modulation unit 11 selects the BPSK modulation method if the average value of the EVM is greater than a predetermined threshold value, and selects the QPSK modulation method if the average value of the EVM is equal to or less than the predetermined threshold value.

  Note that the EVM of each data symbol 201 may be obtained from the EVM of a plurality of pilot symbols 203 using an interpolation method or an extrapolation method.

  Further, the communication quality estimation unit 8 may obtain SINR instead of obtaining EVM. In this case, for example, the amplitude of the corrected reception signal point 502 on the IQ plane is obtained for each of the plurality of pilot symbols 203, and the square of the average value of the obtained plurality of amplitudes is calculated. Then, the value obtained by dividing the average value of the EVM of the plurality of pilot symbols 203 obtained as described above by the square of the average value of the amplitude is defined as interference noise power. Thereafter, an average value of the power of the plurality of pilot symbols 203 is obtained, and the signal power is divided by the interference noise power by using the average value as the signal power. The value thus obtained is SIRN for the entire PRU 200. The power of pilot symbol 203 can be obtained from the amplitude on the IQ plane of reception signal point 502 after correction.

  As described above, in communication apparatus 100 according to the present embodiment, based on the received signal point on the IQ plane of training symbol 202 and the known ideal signal point on the IQ plane for training symbol 202, A correction amount for the reception signal point on the IQ plane of pilot symbol 203 is obtained, and the reception signal point of pilot symbol 203 is corrected based on the correction amount. Communication apparatus 100 estimates communication quality based on the received signal point after correction of pilot symbol 203 and a known ideal signal point on the IQ plane for pilot symbol 203.

  Thus, communication apparatus 100 according to the present embodiment uses two types of known signals, training symbol 202 and pilot symbol 203, to estimate the communication quality, so that the received signal is on the IQ plane. Communication quality can be estimated without performing processing for obtaining bit data corresponding to the received signal point from the received signal point.

  Although it is possible to estimate the communication quality by obtaining EVM or the like based on the difference between the received signal point and the ideal signal point on the IQ plane for the data symbol 201, in this case, the ideal signal of the data symbol 201 Since the point is unknown, it is necessary to obtain the ideal signal point on the IQ plane corresponding to the bit data after obtaining the bit data corresponding to the received signal point based on the received signal point of the data symbol 201. is there.

  In communication apparatus 100 according to the present embodiment, since communication quality can be estimated without performing processing for converting the obtained bit data into signal points on the IQ plane, communication quality can be estimated with simple processing. Can do.

  In the next-generation PHS, instead of data symbols, a PRU 200 including a symbol not including data called a DTX (Discontinuous Transmission) symbol may be transmitted from the communication terminal to the base station. In this case, the base station cannot receive data symbols in a certain time zone. Therefore, when the base station estimates the communication quality using the data symbols, the communication quality cannot be estimated in a certain time zone.

  Since communication apparatus 100 according to the present embodiment can estimate communication quality using only known signals, communication quality can be estimated even when a data symbol as a data signal is not transmitted in a certain time zone. it can.

  As described above, the reception signal point of data symbol 201 can be corrected using pilot symbol 203 received at a time close to the reception time of data symbol 201. The reception signal point of the data symbol 201 can be corrected so as to sufficiently cancel the distortion. Therefore, by estimating the communication quality based on the reception signal point of the data symbol 201 corrected in this way, the communication quality can be estimated with high accuracy.

  On the other hand, the reception signal point of pilot symbol 203 is corrected by using training symbol 202 received at a time slightly away from the reception time of pilot symbol 203, and therefore, the symbol symbol based on transmission path characteristics is corrected. Distortion may not be canceled sufficiently. Therefore, when the communication quality is estimated based on the received signal point corrected for pilot symbol 203 as in the present embodiment, the estimation accuracy of the communication quality is slightly higher than when data symbol 201 is used. May fall.

  However, in modulation apparatus 11, pilot symbol 203 is adjusted in communication apparatus 100 by adjusting a threshold value used when a modulation scheme is determined based on communication quality estimated by communication quality estimation section 8. Even when the modulation scheme is determined based on the communication quality estimated using the data, stable communication equivalent to the case where the modulation scheme is determined based on the communication quality estimated using the data symbol 201 Can be realized.

2 receiving unit 5 signal point acquiring unit 6 correction amount acquiring unit 7 correcting unit 8 communication quality estimating unit 100 communication device 202 training symbol 203 pilot symbol 300,500 received signal point 310 change amount 301,501 ideal signal point

Claims (3)

A receiver for receiving the first and second known signals;
A signal point acquisition unit for obtaining a reception signal point on an IQ plane for each of the first and second known signals received by the reception unit;
A correction amount for the received signal point of the second known signal is obtained based on the received signal point of the first known signal and a known ideal signal point on the IQ plane for the first known signal. A correction amount acquisition unit;
A correction unit that corrects the reception signal point of the second known signal based on the correction amount;
A communication quality estimation unit configured to estimate communication quality based on the received signal point after correction for the second known signal and a known ideal signal point on the IQ plane for the second known signal; ,Communication device. The communication device according to claim 1,
The communication quality estimation unit is configured to perform an EVM (Error Vector Magnitude) or SINR (Signal to Interference) based on the received signal point after correction for the second known signal and the ideal signal point of the second known signal. A communication device that estimates communication quality by obtaining plus noise power ratio. (A) receiving a first known signal;
(B) receiving a second known signal;
(C) obtaining a received signal point on an IQ plane for the first known signal received in the step (a);
(D) obtaining a received signal point on an IQ plane for the second known signal received in the step (b);
(E) Correction of the second known signal for the received signal point based on the received signal point of the first known signal and a known ideal signal point on the IQ plane for the first known signal. A process for determining the quantity;
(F) correcting the received signal point of the second known signal based on the correction amount;
(G) including a step of estimating communication quality based on the received signal point after correction for the second known signal and a known ideal signal point on the IQ plane for the second known signal. Communication quality estimation method.

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