JP5159673B2 - Modulation method estimation device - Google Patents

Description

  The present invention relates to a modulation scheme estimation apparatus that estimates a modulation scheme of a received signal.

  As a conventional technique for estimating a modulation method of a received signal, for example, there is a technique described in Patent Document 1 below. The purpose of this technique is to improve the performance of frame modulation scheme estimation without being affected by errors in the modulation scheme estimation for each burst. As a specific method, for each burst, the reception quality is measured based on BER, SNR or the input power level at the antenna end, and the entire frame is calculated based on the modulation method estimation result for each burst reflecting the measured reception quality. The modulation scheme is estimated and output as a modulation scheme estimation result.

JP 2008-54235 A

  However, according to the above conventional technique, since the length of the processing sequence is the burst length, the processing sequence length cannot be set freely. For this reason, there has been a problem that the performance cannot be improved by improving the reliability of the signal in the apparatus for increasing the processing sequence length. As a result, the estimation accuracy of the modulation scheme cannot be increased. Further, when the reception burst length is increased and the processing sequence length is increased, there is a problem that the reception quality in the burst becomes non-uniform when the reception quality fluctuates such as in a fading environment, and the estimation performance deteriorates.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a modulation scheme estimation apparatus capable of estimating a modulation scheme with high accuracy even when reception quality fluctuates such as in a fading environment. .

In order to solve the above-described problems and achieve the object, the present invention estimates reception quality estimation means for estimating reception quality for each burst of the received signal and a modulation scheme applied to the received signal according to different estimation methods. A plurality of modulation scheme estimation means, and a modulation scheme estimation means corresponding to the reception quality estimated by the reception quality estimation means based on the correspondence between the reception quality range held in advance and the modulation scheme estimation means Output switching means for selecting and outputting the received signal to the selected modulation scheme estimation means, and the modulation scheme estimation means comprises storage means for storing the intermediate signal calculated based on the received signal The modulation method is estimated based on the intermediate signal stored in the storage means, and the estimated result is used as the modulation method determination result.

  According to the present invention, the range of reception quality is associated with the modulation scheme estimation system to be used, the reception quality of the received signal is obtained for each burst, the corresponding modulation scheme estimation system is selected based on the reception quality, and is selected. The modulation method estimation system estimates the modulation method using one or more of the input received signal and the received signal stored by itself, so that even if the reception quality fluctuates, modulation is performed with high accuracy. There is an effect that the estimation of the method can be performed.

FIG. 1 is a diagram illustrating a functional configuration example of a first embodiment of a modulation scheme estimation apparatus according to the present invention. FIG. 2 is a diagram for explaining the S / N estimation method. FIG. 3 is a diagram illustrating a functional configuration example of the modulation scheme estimation apparatus according to the second embodiment. FIG. 4 is a diagram illustrating an example of a simulation result of a modulation scheme estimation probability characteristic when the modulation scheme estimation method of the second embodiment is implemented. FIG. 5 is a diagram illustrating a functional configuration example of the modulation scheme estimation apparatus according to the third embodiment. FIG. 6 is a diagram illustrating a functional configuration example of the modulation scheme estimation apparatus according to the fourth embodiment. FIG. 7 is a diagram illustrating an example in which a reliability information calculation unit and a modulation scheme determination result update unit are added to the modulation scheme estimation apparatus of the second embodiment. FIG. 8 is a diagram illustrating an example in which a reliability information calculation unit and a modulation scheme determination result update unit are added to the modulation scheme estimation apparatus of the third embodiment.

  Embodiments of a modulation scheme estimation apparatus according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a functional configuration example of a first embodiment of a modulation scheme estimation apparatus according to the present invention. As shown in FIG. 1, the modulation scheme estimation apparatus according to the present embodiment includes an S / N estimation unit 1 that estimates an S / N (Signal / Noise) ratio based on a received signal as an estimated value of reception quality; Based on the S / N value (estimated S / N) estimated by the S / N estimation unit 1, the switch 2 that selects the output destination of the received signal to the next stage, and the modulation scheme estimation that estimates the modulation scheme of the received signal And a system group 3. The modulation scheme estimation system group 3 includes modulation scheme estimation systems 31-1 to 31-m.

  Next, the operation of the present embodiment will be described. For example, when the receiving apparatus on which the modulation scheme estimation apparatus of this embodiment is mounted receives a burst of received signals, the modulation scheme estimation processing of this embodiment is started. First, the S / N estimation unit 1 performs S / N estimation for each burst using a burst or the like of the received signal. As the S / N estimation method at this time, for example, there is the following method.

  The received signal sequence is converted into the frequency domain by processing such as discrete Fourier transform or fast Fourier transform on the received signal sequence, and if necessary, a moving average is performed to obtain a power spectrum. Then, the maximum value Smax and the minimum value Smin within a predetermined range of the obtained power spectrum are obtained, and the ratio (Smax / Smin) is set to S / N. FIG. 2 is a diagram for explaining this S / N estimation method. As shown in the figure, Smax is dominated by a desired signal, and Smin is equivalent to a frequency component without a signal and is equivalent to a noise component. The S / N estimation method is not limited to this, and other methods may be used as long as the S / N value is estimated for each burst.

  Next, based on the estimated S / N estimated by the S / N estimator 1, the modulation scheme estimation system 31-i (i = 1 to m) in which the switch 2 performs processing in the modulation scheme estimation system group 3. ). In the present embodiment, the range of estimated S / N is classified into m types, and modulation scheme estimation systems 31-1 to 31-m corresponding to each stage are determined in advance. Based on this correspondence, the switch 2 selects the modulation scheme estimation systems 31-1 to 31-m corresponding to the range to which the input estimated S / N belongs as the modulation scheme estimation system 31-i that performs processing, The received signal is output to the modulation scheme estimation system 31-i.

  The modulation scheme estimation system 31-i to which the received signal is input estimates the modulation scheme of the received signal according to a predetermined estimation method, and outputs an estimation result. The estimation method of the modulation scheme performed by the modulation scheme estimation systems 31-1 to 31-m can improve the estimation accuracy by adopting an estimation method suitable for the corresponding estimation S / N. Note that the modulation method estimation method used at this time includes a buffer (accumulation means) for accumulating feature amounts, such as a modulation method estimation device described in Japanese Patent Application Laid-Open No. 2008-2111760. A method of adding an averaging process of accumulated values performed for error suppression of the feature amount is adopted. The estimation method of the modulation scheme is not limited to this, and any method may be used as long as the estimation method is based on the received signal.

  As an estimation method of the modulation method, there is a method of estimating by accumulating received signals in order to improve the estimation accuracy. However, in the conventional method, the estimation accuracy decreases when processing sequences of different S / N are mixed. To do. In the present embodiment, the modulation scheme estimation systems 31-1 to 31-m can store the received signals and perform the modulation scheme estimation processing for each request S / N. It is possible to prevent a decrease in estimation accuracy due to the mixture of / N processing sequences and improve the estimation accuracy.

  Thus, in the present embodiment, the estimated S / N of the received signal is obtained for each burst, the modulation scheme estimation systems 31-1 to 31-m are selected for each estimated S / N, and the selected modulation scheme is selected. The estimation system 31-i estimates the modulation method using the input received signal, the received signal stored by itself, and the like. Therefore, the modulation scheme estimation can be executed by increasing the processing sequence length used for estimation without mixing the received signals of different S / N, so that the modulation scheme estimation with high accuracy can be performed. In particular, in a fading environment where the S / N varies, the effect of improving estimation accuracy by the modulation scheme estimation method of the present embodiment is high.

Embodiment 2. FIG.
FIG. 3 is a diagram illustrating a functional configuration example of the second embodiment of the modulation scheme estimation apparatus according to the present invention. As shown in FIG. 3, the modulation scheme estimation apparatus according to the present embodiment includes S / N estimation section 1 and modulation scheme estimation system 4 similar to those in the first embodiment. Components having the same functions as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and description thereof is omitted.

  The modulation scheme estimation system 4 performs a predetermined process for estimating a modulation scheme based on a burst of a received signal, and uses a first modulation scheme estimation module 41 that uses the processing result as an intermediate signal, and a first modulation scheme A switch 42 for selecting an output destination of the intermediate signal output from the estimation module 41 based on the S / N value estimated by the S / N estimation unit 1, and an intermediate signal of the first modulation scheme estimation module 41 are accumulated. A storage device group 43 that performs predetermined signal processing on the intermediate signals if necessary; a second modulation estimation method module 44 that performs modulation method estimation based on the intermediate signals output from the storage device group 43; Consists of. The storage device group 43 includes storage devices 45-1 to 45-m. The estimated S / N value range and the storage devices 45-1 to 45-m are preliminarily stored in the same manner as the correspondence between the modulation scheme estimating systems 31-1 to 31-m of the first embodiment and the S / N value range. Assume that they are associated. Then, the switch 42 outputs the intermediate signal of the first modulation scheme estimation module to the storage devices 45-1 to 45-m corresponding to the S / N values estimated by the S / N estimation unit 1 based on the correspondence. To do.

  Next, the operation of the present embodiment will be described. The operation from when the burst of the received signal is received until the S / N estimation unit 1 estimates the S / N value based on the received signal is the same as in the first embodiment. The received signal is also input to the first modulation scheme estimation module 41. The first modulation scheme estimation module 41 performs processing for estimating the modulation scheme based on the received signal. As this measure, for example, processing such as transmission rate correction, frequency deviation correction, removal of out-of-band interference components, and calculation of feature quantities are performed. Then, the first modulation scheme estimation module 41 calculates an intermediate signal using the processing result as an intermediate signal. The switch 42 selects the storage devices 45-1 to 45-m that are the output destinations of the intermediate signals based on the S / N value estimated by the S / N estimation unit 1, and the selected storage devices 45-1 to 45-m. Output an intermediate signal.

  The storage devices 45-1 to 45-m perform predetermined signal processing when necessary for the input intermediate signals, respectively, and perform intermediate signal processing (signals after treatment when signal processing is performed). ). The storage devices 45-1 to 45-m output the accumulated signals to the second modulation scheme estimation module 44 in a predetermined unit (signal sequence). The second modulation scheme estimation module 44 estimates a modulation scheme based on the input signal sequence and outputs an estimation result. As the estimation process at this time, for example, a feature amount evaluation process is performed. If the storage devices 45-1 to 45-m do not accumulate a plurality of signals, the storage devices 45-1 to 45-m output the input signals to the second modulation scheme estimation module 44, and The second modulation scheme estimation module 44 performs modulation scheme estimation based on the input signal.

  As described above, in the present embodiment, the first modulation scheme estimation module 41 implements the processing for modulation scheme estimation performed individually for each S / N value of the received signal in the first embodiment in common. doing. Then, for each S / N value, the storage devices 45-1 to 45-m accumulate intermediate signals as processing results. If there are different processing parts for each S / N value for the modulation scheme estimation, the shared storage devices 45-1 to 45-m may perform the processing.

  FIG. 4 is a diagram illustrating an example of a simulation result of the modulation scheme estimation probability characteristic when the modulation scheme estimation method of the present embodiment is implemented. The horizontal axis of the figure indicates the fading period. In a fading environment, it can be seen that the method of this embodiment (the proposed method) has a higher identification probability than the conventional method using a single storage device.

  As described above, in the present embodiment, intermediate signals obtained by processing bursts of received signals are accumulated in the storage devices 45-1 to 45-m for each range of S / N values, and the second The modulation scheme estimation module 44 estimates the modulation scheme using the accumulated result. For this reason, the modulation scheme estimation can be executed by increasing the processing sequence length used for estimation without mixing signals of different S / N values, so that a highly accurate modulation scheme estimation can be performed. In addition, since the first modulation scheme estimation module 41 performs processing that can be shared, the processed signals are accumulated for each S / N value range, so that it is easier to implement than the first embodiment. Is possible.

Embodiment 3 FIG.
FIG. 5 is a diagram illustrating a functional configuration example of the third embodiment of the modulation scheme estimation apparatus according to the present invention. As shown in FIG. 5, the modulation scheme estimation apparatus according to the present embodiment includes S / N estimation section 1 similar to that of the first embodiment and modulation scheme estimation system 4a. Components having the same functions as those in the first embodiment or the second embodiment are denoted by the same reference numerals as those in the first or second embodiment, and description thereof is omitted.

  The modulation scheme estimation system 4a is different from the modulation scheme estimation system 4 of the second embodiment except that the storage device group 43 and the second modulation scheme estimation module 44 are replaced with a storage device group 46 and a third modulation scheme estimation module 47, respectively. Is the same as that of the modulation system 4 of the second embodiment. The storage device group 46 includes modules 48-1 to 48-m and storage devices 49-1 to 49-m.

  Next, the operation of the present embodiment will be described. The operation from when the burst of the received signal is received until the S / N estimation unit 1 estimates the S / N value based on the received signal is the same as in the first embodiment. The operation of the first modulation scheme estimation module 41 is the same as that of the second embodiment, but in the present embodiment, the first modulation scheme estimation module 41 does not need to reflect the estimated S / N. To implement. The switch 42 selects the output destination of the intermediate signal that is the output of the first modulation scheme estimation module 41 based on the S / N value estimated by the S / N estimation unit 1 as in the second embodiment. The output destination is selected from the modules 48-1 to 48-m. The correspondence between the modules 48-1 to 48-m and the S / N value ranges is determined in advance in the same manner as the correspondence between the storage devices 45-1 to 45-m and the S / N value ranges in the second embodiment. I will keep it.

  The module 48-i (i = 1 to m) performs processing of a portion that needs to reflect the estimated S / N in the processing for estimating the modulation scheme, and stores the processed signal in the storage device 49- accumulate in i. The storage device 49-i outputs the accumulated signal or signal sequence to the third modulation scheme estimation module 47. Similar to the second modulation scheme estimation module 44 of the second embodiment, the third modulation scheme estimation module 47 performs modulation scheme estimation based on the input signal or signal sequence, and outputs an estimation result. .

  As described above, in the present embodiment, the first modulation scheme estimation module 41 performs a process that does not require the estimated S / N to be reflected, and the processed signal is processed according to the estimated S / N value. It was made to accumulate | store for every estimated S / N value after implementation. Therefore, a simpler configuration than that of the first embodiment can be obtained. In addition, since the modules 48-1 to 48-m perform the processing for improving the processing accuracy by reflecting the estimated S / N for each S / N value, the estimation accuracy is higher than that of the second embodiment. Can be improved.

Embodiment 4 FIG.
FIG. 6 is a diagram illustrating a functional configuration example of the fourth embodiment of the modulation scheme estimation apparatus according to the present invention. As shown in FIG. 6, the modulation scheme estimation apparatus according to the present embodiment is the same as the modulation scheme estimation apparatus according to the first embodiment except that a reliability information calculation unit 5 and a modulation scheme determination result update unit 6 are added. It is the same as that of the modulation system estimation apparatus of the form 1. Components having the same functions as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and description thereof is omitted.

  The reliability information calculation unit 5 calculates reliability information based on the S / N value estimated by the S / N estimation unit 1. The modulation scheme determination result update unit 6 accumulates a result of the modulation scheme estimation system group 3 estimating the modulation scheme (modulation scheme determination result) and reliability information, and updates the modulation scheme determination result based on the accumulated value.

  Next, the operation of the present embodiment will be described. The operation from when the received signal burst is received until the S / N estimation unit 1 estimates the S / N value based on the received signal is the same as in the first embodiment. The N estimation unit 1 also outputs the estimated S / N value to the reliability information calculation unit 5. The reliability information calculation unit 5 calculates reliability information based on the S / N value estimated by the S / N estimation unit 1 and outputs the reliability information to the modulation scheme determination result update unit 6. As the reliability information, any information may be used as long as the reliability information is high when the S / N value is good.

  The switch 2 and the modulation scheme estimation system group 3 perform the same operation as in the first embodiment, and the modulation scheme estimation system group 3 outputs the modulation scheme determination result to the modulation scheme determination result update unit 6. The modulation scheme determination result update unit 6 stores the modulation scheme determination result and reliability information in association with each other, and modulates based on the stored predetermined period or a predetermined number of modulation scheme determination results and reliability information. The determination result of the method is comprehensively obtained, and the determination result is updated with the obtained value. At this time, for example, the determination result of the modulation method with high reliability information is weighted to obtain a comprehensive determination result.

  In the example of FIG. 6, the reliability information calculation unit 5 and the modulation scheme determination result update unit 6 are added to the modulation scheme estimation apparatus of the first embodiment. Alternatively, the reliability information calculation unit 5 and the modulation scheme determination result update unit 6 are added to the third embodiment, and the calculation of the reliability information and the update process of the modulation scheme determination result are added as in the present embodiment. May be.

  FIG. 7 is a diagram illustrating an example in which a reliability information calculation unit 5 and a modulation scheme determination result update unit 6 are added to the modulation scheme estimation apparatus of the second embodiment. In this case, the modulation scheme determination result update unit 6 updates the determination result based on the determination result that is the output of the second modulation scheme estimation module 44 and the reliability information. FIG. 8 is a diagram illustrating an example in which a reliability information calculation unit 5 and a modulation scheme determination result update unit 6 are added to the modulation scheme estimation apparatus of the third embodiment. In this case, the modulation scheme determination result update unit 6 updates the determination result based on the determination result that is the output of the third modulation scheme estimation module 47 and the reliability information.

  In the present embodiment, the reliability information is calculated based on the S / N value estimated by the S / N estimation unit 1. However, the present invention is not limited to this, and other receptions such as the input power level at the antenna end. The reliability information may be calculated using the quality. Further, reliability information may be calculated based on a plurality of reception qualities.

  As described above, in this embodiment, in this embodiment, the reliability information calculation unit 5 and the modulation method determination result update unit 6 are added to the modulation method estimation apparatus of the first embodiment, and the modulation method determination result is updated. The unit 6 accumulates the determination result of the modulation scheme estimation system group 3 and the reliability information calculated by the reliability information calculation unit 5, and updates the determination result based on the accumulated information. Therefore, the modulation scheme can be determined with higher accuracy than in the first embodiment.

  As described above, the modulation scheme estimation apparatus according to the present invention is useful for a modulation scheme estimation apparatus that estimates the modulation scheme of a received signal, and in particular, a modulation scheme estimation apparatus that is used in a fading environment in which S / N varies. Suitable for

DESCRIPTION OF SYMBOLS 1 S / N estimation part 2 Switch 3 Modulation system estimation system group 31-1-31-m, 4, 4a Modulation system estimation system 41 1st modulation system estimation module 42 Switch 43, 46 Storage device group 44 2nd modulation | alteration Method estimation module 45-1 to 45-m, 49-1 to 49-m Storage device 47 Third modulation method estimation module 48-1 to 48-m Module 5 Reliability information calculation unit 6 Modulation method determination result update unit

Claims (6)

Reception quality estimation means for estimating reception quality for each burst of received signal;
A plurality of modulation scheme estimation means for estimating the modulation scheme applied to the received signal according to different estimation methods ;
Based on the correspondence between the reception quality range held in advance and the modulation scheme estimation means, the modulation scheme estimation means corresponding to the reception quality estimated by the reception quality estimation means is selected, and the selected modulation scheme estimation means Output switching means for outputting the received signal to
With
The modulation scheme estimation means includes
Storage means for storing an intermediate signal calculated based on the received signal;
With
A modulation method estimation apparatus, wherein a modulation method is estimated based on an intermediate signal stored in the storage means, and the estimated result is used as a modulation method determination result. Reception quality estimation means for estimating reception quality for each burst of received signal;
First modulation scheme estimating means for calculating an intermediate signal used for estimating the modulation scheme based on the received signal;
A plurality of storage means for storing the intermediate signal;
Based on the correspondence between the reception quality range stored in advance and the storage means, the storage means corresponding to the reception quality estimated by the reception quality estimation means is selected, and the estimated value is stored in the selected storage means. Output switching means for outputting an intermediate signal calculated based on a corresponding received signal;
Second modulation scheme estimation means for estimating a modulation scheme based on the intermediate signal accumulated in the accumulation means, and using the estimated result as a modulation scheme determination result;
A modulation scheme estimation apparatus comprising: Reception quality estimation means for estimating reception quality for each burst of received signal;
First modulation scheme estimating means for calculating an intermediate signal used for estimating the modulation scheme based on the received signal;
A plurality of second modulation scheme estimation means for performing processing depending on reception quality for estimating the modulation scheme on the intermediate signal and outputting the implemented signal as individual intermediate signals;
Storage means for storing the individual intermediate signals output by the second modulation scheme estimation means for each of the second modulation scheme estimation means;
Based on the correspondence between the reception quality range held in advance and the second modulation scheme estimation means, the second modulation scheme estimation means corresponding to the estimated value is selected, and the selected second modulation scheme estimation is selected. An output switching means for outputting an intermediate signal calculated based on the received signal corresponding to the estimated value to the means;
A third modulation scheme estimating means for estimating a modulation scheme based on the intermediate signal accumulated in the accumulation means and using the estimated result as a modulation scheme determination result;
A modulation scheme estimation apparatus comprising: Reliability information calculating means for calculating reliability information based on the reception quality of the received signal;
Determination result updating means for accumulating the reliability information and the modulation scheme determination result, and updating the modulation scheme determination result based on the stored reliability information and the modulation scheme determination result;
The modulation scheme estimation apparatus according to claim 1, further comprising:   The reception quality estimation means converts the frequency of the received signal into a frequency signal, derives a ratio between a maximum value and a minimum value within a predetermined frequency range of the frequency signal as an estimated value of the signal-to-noise ratio, The modulation method estimation apparatus according to any one of claims 1 to 4, wherein   The reception quality estimation means converts the frequency of the received signal into a frequency signal, calculates a moving average of the frequency signal, and a ratio between a maximum value and a minimum value within a predetermined frequency range of the signal after the moving average processing is performed. 5 is derived as an estimated value of the signal-to-noise ratio to obtain reception quality. 5. The modulation method estimation apparatus according to claim 1, wherein reception quality is obtained.

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