KR100662516B1 - Apparatus and method for estimating quality of modulated receiving signal - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to an apparatus and method for estimating a signal-to-noise ratio of a modulated received signal.

2. The technical problem to be solved by the invention

The present invention provides a method for quantizing a signal whose absolute value of a received signal is greater than or equal to a threshold at a receiving end of a digital communication system, and re-adjusting a signal-to-noise ratio (SNR) estimation range according to the distribution of the quantized signal and applying a weight accordingly. It is an object of the present invention to provide an apparatus and method for estimating a signal-to-noise ratio of a modulated received signal to efficiently estimate the quality of a received signal.

3. Summary of Solution to Invention

An apparatus for estimating a signal-to-noise ratio of a modulated received signal, the apparatus comprising: signal selecting means for selecting a signal whose absolute value is greater than or equal to a threshold value for a predetermined number of received signals; Quantization means for storing the signal selected by the signal selection means as a signal of a corresponding range among preset quantization ranges; Symbol number checking means for counting the number of symbols stored in a quantization range preset by said quantization means; Estimation range re-adjustment means for re-adjusting a range to be used for signal-to-noise ratio estimation according to the distribution of the number of symbols confirmed by the symbol number confirmation means; Intermediate value calculating means for calculating a median value for estimating a signal-to-noise ratio by applying weights to the range readjusted by the estimated range readjustment means; And signal-to-noise ratio estimating means for estimating a signal-to-noise ratio corresponding to the median value calculated by the intermediate value calculating means.

4. Important uses of the invention

The invention is used in digital communication systems and the like.

PSK modulation scheme, quality estimation of modulated received signal, range reestimation, digital communication system

Description

Apparatus and method for estimating quality of modulated receiving signal             

1 is a configuration diagram of an embodiment of a digital communication system to which the present invention is applied;

2A is a diagram illustrating an embodiment of signal values in an I-channel and a Q-channel according to symbol mapping in a BPSK modulation scheme;

FIG. 2B is a diagram illustrating an embodiment of signal values in an I-channel and a Q-channel according to symbol mapping in a QPSK modulation scheme; FIG.

FIG. 2C is a diagram illustrating an embodiment of signal values in an I-channel and a Q-channel according to symbol mapping in an 8-PSK modulation scheme; FIG.

FIG. 2D is a diagram illustrating an embodiment of signal values in an I-channel and a Q-channel according to symbol mapping in a 16-PSK modulation scheme; FIG.

3 is an exemplary explanatory diagram of a conventional signal-to-noise ratio estimation method;

4A is a diagram illustrating a relationship between a linear combination result value and a signal-to-noise ratio (SNR) in QPSK according to a conventional signal-to-noise ratio estimation method.

4B is a view showing a relationship between a linear combination result value and a signal-to-noise ratio (SNR) in 16-PSK according to a conventional signal-to-noise ratio estimation method;

5 is an explanatory diagram of an embodiment of a distribution of a received signal according to a signal-to-noise ratio (SNR) and accordingly a quantization method used in the present invention;

6 is a block diagram of an embodiment of an apparatus for estimating a signal-to-noise ratio of a modulated received signal according to the present invention;

7 is a flowchart illustrating a method for estimating a signal-to-noise ratio of a modulated received signal according to the present invention.

* Explanation of symbols for the main parts of the drawings

61 signal selection unit 62 quantization unit

63: symbol count confirmation unit 64: estimated range readjustment unit

65: intermediate value calculator 66: signal-to-noise ratio estimation unit

The present invention relates to an apparatus for estimating a signal-to-noise ratio of a modulated received signal, and more particularly, to a signal in which a magnitude of an absolute value of a received signal is greater than or equal to a threshold at a receiving end of a digital communication system. An apparatus and method for estimating a signal-to-noise ratio of a modulated received signal for efficiently estimating the quality of a received signal by readjusting a signal-to-noise ratio (SNR) estimation range according to a distribution and applying a weight thereof accordingly will be.

In general, in digital modulation, a signal is transmitted by changing one or a combination of phase, amplitude, and frequency of a carrier wave into digital data of 0's and 1's. Transmitting a signal by matching a sign to a phase change is called phase shift keying (PSK).

Binary phase shift keying (BPSK) is a basic phase shift keying scheme in which a digital signal having two values (0 or 1) to be transmitted is transmitted in correspondence with two phases of a carrier (ie, zero phase and π phase). Referred to as 'BPSK'.

Unlike BPSK, two bits of digital signals 0 and 1 of two values are collected and transmitted in correspondence with the four phases of the carrier and are referred to as quadrature PSK (QPSK). That is, it transmits by correlating (0, 0) with 0 phase, (0, 1) with π / 2 phase, (1, 0) with π phase, and (1, 1) with 3π / 2 phase. Binary phase shift keying (BPSK) is also referred to as two-phase shift keying and quadrature phase shift keying (QPSK) is also referred to as four-phase shift keying. QPSK modulated waves can transmit twice as much information as BPSK modulated waves in the same frequency band, and are widely used in the voice signal transmission and satellite communication fields of satellite broadcasting.

On the other hand, there are 8 phase shift key modulation (8PSK, hereinafter referred to as '8PSK') that can transmit 3 times the information in the same frequency band, and 16 phase shift modulation (16PSK) that can transmit 4 times the information.

To date, techniques for estimating the quality of a digitally modulated received signal include calculating a bit error rate (BER) from the received signal to estimate the quality and calculating a signal-to-noise ratio (SNR) from the PSK modulated receive signal. There is this.

US Pat. Nos. 4,393,499 and 4,580,263 describe a method for estimating the quality of a received signal by constructing a circuit capable of measuring a bit error rate (BER) at a receiver for a PSK modulated received signal. In addition, U.S. Patent No. 5,590,158 proposed by "Yamaguchi" (Name of the method and apparatus for estimating PSK modulated signals / Inventor: Yamaguchi et al. / Applicant: Advantest Corporation / Registration Date: December 31, 1996) An attempt was made to estimate the received signal quality from the digital signals of the I and Q channels of the signal. However, the method of estimating the received signal quality proposed by "Yamaguchi" has a disadvantage in that it can be efficiently applied only to the differential QPSK (DQPSK) method.

On the other hand, conventionally, a method for simply calculating a signal-to-noise ratio (SNR) of a received signal using an average value and a variance of about 500 received signals has been published in the paper (see S. Gunaratne, P. Taaghol, and R. Tafazolli, "Signal quality estimation algorithm", Electronics Letters, Vol. 36, No. 22, pp. 1882-1884, Oct. 2000). However, the above method has a problem in that it is impossible to use the PSK signal over the QPSK and the estimation is impossible in the environment where the signal-to-noise ratio is lower than 0 dB.

On the other hand, in relation to the received signal quality estimation method, the "rain attenuation compensation method using an adaptive transmission technique" (Korean Patent Application No. 10-2000-0059780, filed on October 11, 2000) is as follows.

This patent proposes a method of estimating the signal-to-noise ratio (SNR) of a PSK modulated received signal for estimating the received signal quality which must be accompanied for adaptive transmission. However, this method has non-uniform estimation error according to the estimated SNR value by using uniform quantization level and weight regardless of SNR value, and the estimated SNR value is also limited within a certain range. In addition, a more serious problem is that when using this method, the SNR cannot be estimated in the high-order PSK modulation scheme (16-PSK or more). This will be described in detail with reference to FIG. 3.

1 is a configuration diagram of an embodiment of a digital communication system to which the present invention is applied.

As shown in FIG. 1, in the digital communication system to which the present invention is applied, a binary signal output from a binary data source 101 at a transmitting end 10 is mapped to an M-ary PSK symbol at a symbol mapper 102. Signals (mapped), mapped to PSK symbols, are sent on the I-channel and Q-channel.

Thereafter, the signals transmitted on the I-channel and Q-channel are added to the noise generated in the channel 12 and arrive at the receiving end 11. Signals arriving at the I-channel and Q-channel are passed through the signal-to-noise ratio (SNR) estimator 111, and the quality of the received signal is calculated or estimated and then input to the symbol inverter 112, and the input signal is The symbol inverse in the demodulator 112 is demodulated to a binary signal.

2A to 2D are exemplary diagrams illustrating signal values in an I-channel and a Q-channel according to symbol mapping in an M-ary PSK modulation scheme.

As shown in FIG. 2A, one bit is mapped to one symbol in the BPSK modulation scheme. Therefore, data is transmitted only through the I-channel, and the value of the signal transmitted through the I-channel is 1 or -1.

On the other hand, in the QPSK modulation scheme, as shown in FIG. 2B, two bits are mapped to one symbol, and values of signals transmitted through the I-channel and the Q-channel for each symbol are 0.707 and -0.707.

As described above, in the case of the BPSK modulation method or the QPSK modulation method, the absolute amplitude of data transmitted on the I-channel and the Q-channel is always constant (1 or 0.707).

However, in the modulation scheme of 8-PSK or more, the absolute size of data transmitted on the I-channel and the Q-channel may be various values. As shown in FIG. 2C and FIG. 2D, in the case of 8-PSK, there are two absolute sizes of data transmitted in I-channel and Q-channel, 0.3827 and 0.9239, and 0.276, 0.786, and 1.176 in 16-PSK. , And 1.387.

3 is a diagram illustrating a conventional signal-to-noise ratio estimation method, and shows a signal-to-noise ratio (SNR) estimation method used in Korean Patent Application No. "10-2000-0059780".

As shown in Fig. 3, the conventional signal-to-noise ratio (SNR) estimation method first modulates the M-ary PSK to normalize the level of the received signal. Thereafter, quantization is performed on the normalized signal (before quantization) 31.

Subsequently, a linear combination is performed by adding weights to the quantized signals (after quantization) 32. Here, in order to linearly combine, a weight such as 0, 1, 4, 9, ... is applied symmetrically around the signal 31 level 1 after quantization.

Then, the signal-to-noise ratio (SNR) corresponding to the linear combination result is converted.

The conventional signal-to-noise ratio estimation method described above can be applied to BPSK and QPSK signals. However, in 8-PSK or more modulation schemes, the absolute magnitude of the signal mapped to the I-channel and the Q-channel is two or more, and the interval between each adjacent signal becomes narrower, which interferes with the adjacent signal. Therefore, there is a problem that it is difficult to apply the same method as in the BPSK signal and the QPSK signal in a situation where the interval between each symbol becomes narrower as in the modulation scheme of 8-PSK or more.

4A to 4B are diagrams illustrating a relationship between a linear combination result and a signal-to-noise ratio (SNR) according to a conventional signal-to-noise ratio estimation method.

As shown in Figs. 4A to 4B, in the case of the QPSK modulation scheme, the relationship between the linear combination result value and the signal-to-noise ratio (SNR) has a simple reduction relationship, while in the 16-PSK modulation scheme, it is not a simple reduction relationship. . Therefore, one-to-one mapping between the linear combination result and the signal-to-noise ratio (SNR) is impossible.

In addition, the conventional signal-to-noise ratio estimation method applies the same quantization range over the entire range regardless of the signal-to-noise ratio (SNR) value. However, in the actual situation, the distribution of the received signal based on the center value is very different depending on the signal-to-noise ratio (SNR) value. Therefore, it can be predicted that if a non-uniform quantization method is used according to the signal-to-noise ratio (SNR) value, accurate estimation will be possible in a wider range.

Meanwhile, the conventional signal-to-noise ratio estimation method applies the same weight over the entire range regardless of the signal-to-noise ratio (SNR) value. However, if the signal-to-noise ratio (SNR) value is high, the range of most received signals is centered around the center value. Since the weight given to the center value is zero, a linear combination multiplied by the weight at some signal-to-noise ratio (SNR) There is a problem that it is difficult to estimate the signal-to-noise ratio (SNR) because the result value is zero.

The present invention has been proposed to solve the above-mentioned problem, and a signal-to-noise ratio (SNR) estimation range according to a distribution of quantized signals is obtained by quantizing a signal whose absolute value of a received signal is greater than or equal to a threshold at a receiving end of a digital communication system. It is an object of the present invention to provide an apparatus and a method for estimating a signal-to-noise ratio of a modulated received signal to efficiently estimate the quality of a received signal by re-adjusting and applying a weight accordingly.

Other objects and advantages of the present invention can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. Also, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

An apparatus of the present invention for achieving the above object is a signal-to-noise ratio estimation apparatus of a modulated received signal, comprising: signal selecting means for selecting a signal whose absolute value is greater than or equal to a threshold value for a predetermined number of received signals; ; Quantization means for storing the signal selected by the signal selection means as a signal of a corresponding range among preset quantization ranges; Symbol number checking means for counting the number of symbols stored in a quantization range preset by said quantization means; Estimation range re-adjustment means for re-adjusting a range to be used for signal-to-noise ratio estimation according to the distribution of the number of symbols confirmed by the symbol number confirmation means; Intermediate value calculating means for calculating a median value for estimating a signal-to-noise ratio by applying weights to the range readjusted by the estimated range readjustment means; And signal-to-noise ratio estimating means for estimating a signal-to-noise ratio corresponding to the median value calculated by the intermediate value calculating means.

In addition, the method of the present invention for achieving the above object, in the method for estimating the signal-to-noise ratio of the modulated received signal, signal selection for selecting a signal whose absolute value is greater than or equal to a threshold value for a predetermined number of received signals step; A quantization step of storing the selected signal as a signal having a corresponding range among preset quantization ranges; A symbol number checking step for counting the number of symbols stored in the quantization range; A determination step of determining whether the selected range is greater than or equal to a predetermined number Nc by selecting a range in which the checked number of symbols is greater than a predetermined value n_min; As a result of the determination in the determination step, the additional range is selected so that the predetermined range is less than the predetermined number, and the weight value is applied to the predetermined number range to calculate a median value for estimating the signal-to-noise ratio. An intermediate value calculation step; A second intermediate value calculation step of grouping adjacent ranges according to the determination result of the determination step and calculating a median value for estimating a signal-to-noise ratio by grouping adjacent ranges according to the selected range having a predetermined number or more; And a signal-to-noise ratio estimating step of estimating a signal-to-noise ratio corresponding to the calculated intermediate value.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, whereby those skilled in the art may easily implement the technical idea of the present invention. There will be. In addition, in describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The features of the present invention are summarized as follows.

In the present invention, in order to solve the conventional problem, a non-uniform quantization method based on a signal-to-noise ratio (SNR) value is selected. However, the problem is that the signal-to-noise ratio (SNR) value cannot be known before the estimation of the signal-to-noise ratio (SNR), and the quantization range must be applied before quantizing the signal-to-noise ratio (SNR) value. There is.

Therefore, in the present invention, at first, a range of signals is examined by applying a very fine quantization level, and when a distribution survey for a predetermined number of received signals is completed, a range rebalancing process for estimating the quality of a received signal is performed. Perform.

On the other hand, the present invention takes a method of examining only the distribution of the values that are greater than or equal to the maximum value of the absolute value of the signal mapped to the I-channel and Q-channel. In this case, the interference applied from the adjacent signal can be minimized. Also, since the probability density distribution function for the received signal is symmetrical with respect to the center value, the distribution of the signal with the signal-to-noise ratio (SNR) value that is sufficiently stable with only one distribution is obtained. You can get a relationship.

2C to 2D, in the case of the present invention, in the case of 8-PSK, the distribution is examined only for a signal having an absolute value of 0.9239 or more among the signals coming into the I-channel and the Q-channel. In the case of -PSK, the distribution is examined only for signals above 1.387.

5 is an explanatory diagram of one embodiment of a distribution of a received signal according to a signal-to-noise ratio (SNR) and accordingly a quantization method used in the present invention.

As shown in FIG. 5, the received signals are quantized into Nf (eg, 8) ranges for signals larger than the center value, and the number of signals corresponding to each range is counted and stored. If the signal-to-noise ratio (SNR) is high, most of the received signals are distributed near the center value, so that the number of signals included in the quantization range located near the center value is large and there are few signals that are distributed elsewhere. will be. On the other hand, if the signal-to-noise ratio (SNR) is low, the signal will be distributed over the entire quantization range.

On the other hand, in the present invention, by selecting only a distribution in which the number of signals corresponding to each quantization range is a certain number or more, the range is adjusted to be smaller than the originally investigated range.

In the following description, the range Nc multiplied by the weight is adjusted to four. [Table 1] is an example of a result of examining distribution of a total of 100 signals by dividing all portions larger than the center value into 8 based on a random center value.

Nf = 8 If the SNR is high Low SNR Initial weights Range 1 57 16 0 Range 2 32 15 2 Range 3 10 15 4 Range 4 One 14 6 Range 5 0 13 8 Range 6 0 10 10 Range 7 0 9 12 Range 8 0 8 14

First of all, if the number of signals examined in each range is greater than zero (ie, n_min = 0), then select only range 1 to range 4 when the SNR is high, and select all ranges when the SNR is low. do.

Here, since Nc is assumed to be 4, when the SNR is high, the number of signals stored in the selected range may be multiplied by the initial weight. On the other hand, if the SNR is low, a total of eight ranges have been selected, in which case they must be re-adjusted to four ranges by combining adjacent ranges. In other words, when integrated, the new range 1 is added with the values stored in the existing range 1 and range 2. In this case, assuming that the weight takes the middle value of the two ranges, the weight can be summarized as shown in Table 2 below.

Nc = 4 If the SNR is high, the number (weighted) If the SNR is low, the number (weighted) Range 1 57 (0) 31 (1) Range 2 32 (2) 29 (5) Range 3 10 (4) 23 (9) Range 4 1 (6) 17 (13)

6 is a block diagram of an embodiment of an apparatus for estimating a signal-to-noise ratio of a modulated received signal according to the present invention.

As shown in FIG. 6, the apparatus for estimating a signal-to-noise ratio of a modulated received signal according to the present invention is a signal for selecting a signal whose absolute value is greater than or equal to a threshold for a predetermined number of received signals. A quantization unit 62 and a quantization range preset by the quantization unit 62 for storing the signal selected by the selection unit 61, the signal selected by the signal selection unit 61 as a signal having a corresponding range among the quantization ranges preset. A symbol count checker 63 for counting the number of symbols stored in the apparatus, and an estimation range readjuster for readjusting a range to be used for signal-to-noise ratio estimation according to the distribution of the number of symbols checked by the symbol count checker 63; (64), an intermediate value calculating section 65 for calculating a median value for estimating a signal-to-noise ratio by applying weights to the range adjusted by the estimated range readjustment section 64, and the intermediate value delay. And a signal-to-noise ratio estimation unit 66 for estimating the signal-to-noise ratio corresponding to the intermediate value section 65 is calculated.

The operation of the component will be described in more detail with reference to FIG. 7.

7 is a flowchart illustrating a method for estimating a signal-to-noise ratio of a modulated received signal according to the present invention.

First, the signal selector 61 initializes a count that is a variable for the number of received signals (count = 0) (701). Here, the received signal is a signal received through the I channel and the Q channel, respectively.

Thereafter, when the signal selector 61 receives the received signal (702), the count is increased by one (count = count + 1) (703).

The signal selector 61 then determines whether the absolute value of the received signal is greater than or equal to the threshold (704). Here, the threshold of the received signal is the maximum value of the values mapped to the I channel and the Q channel and transmitted (for example, 0.9329 in the 8PSK method and 1.387 in the 16PSK method).

As a result of the determination 704, if the absolute value of the received signal is not more than the threshold value, the process proceeds to " 702 ".

On the other hand, if the absolute value of the received signal is greater than or equal to the threshold 704, the quantization unit 62 finds the corresponding quantization range among the Nf quantization ranges and increments the counter of the corresponding range by one (that is, each quantization range). The number of signals corresponding to the number is stored and stored) (705). Here, the quantization range is a range divided by a predetermined number Nf for a signal whose absolute value of the received signal is equal to or greater than the threshold.

Thereafter, it is determined whether the value of count, which is the number of received signals, reaches a predetermined value (that is, whether or not observation of a predetermined number of received signals has been completed) (706).

As a result of the determination 706, if the value of the count does not reach the predetermined value, the process proceeds to step 702.

On the other hand, when the determination result 706, the value of the count reaches a predetermined value, the symbol number confirmation unit 63 checks the number of symbols stored in the Nf range, the stored value is a predetermined value ( A range larger than n_min) is selected (707).

Thereafter, the estimated range readjustment unit 64 determines whether the number of the selected ranges is smaller than Nc (708). The number Nc of the predetermined range is smaller than the predetermined number of quantization ranges Nf.

As a result of the determination 708, if the number of selected ranges is smaller than Nc, the estimated range readjustment unit 64 selects additional ranges so that a total of Nc are selected in order of the stored values among the unselected ranges in greater order. 709).

Thereafter, the intermediate value calculator 65 calculates the median value of the signal-to-noise ratio (SNR) conversion by multiplying the initial weight by the values stored in the Nc range (step 713).

On the other hand, if the result of the determination 708, the number of the selected range is not less than Nc, the estimated range readjustment unit 64 regroups adjacent ranges to Nc ranges (711).

Thereafter, the median value calculator 65 calculates the median value of the signal-to-noise ratio (SNR) conversion by multiplying the median value of the initial weights by the values stored in the readjusted Nc ranges (712).

Then, the signal-to-noise ratio estimator 66 fits into a look-up table or polynomial function obtained from a simulation result of the median of the signal-to-noise ratio (SNR) conversion and the signal-to-noise ratio (SNR) value. The estimated signal-to-noise ratio (SNR) based on the calculated median signal-to-noise ratio (SNR) is estimated using the calculated circuit (713).

After the signal-to-noise ratio (SNR) is calculated, once the observation of the received signal is finished, the quality of the received signal is estimated while repeating the entire process from the beginning.

In other words, if a signal is stored in Nf quantization ranges for a certain number of signals, only the range where the number of stored signals is greater than or equal to the predetermined number n_min is selected and readjusted to fewer Nc quantization ranges. Find the distribution of the signal. That is, if the selected range is less than Nc during the readjustment, the range is additionally selected so that a total of Nc may be selected in order of the stored values among the unselected ranges. In this case, the intermediate value for conversion to SNR is calculated by multiplying the weights of the respective initially specified ranges.

On the other hand, if the number of selected ranges is greater than Nc, the ranges are readjusted to Nc by grouping adjacent ranges together and adding the number of signals stored in each range. In this case, an intermediate value for converting to an SNR may be calculated by calculating a weight corresponding to the middle of the grouped ranges among the weights of each initially designated range.

As described above, the method of the present invention may be implemented as a program and stored in a recording medium (CD-ROM, RAM, ROM, floppy disk, hard disk, magneto-optical disk, etc.) in a computer-readable form. Since this process can be easily carried out by those skilled in the art will not be described in more detail.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the technical spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by the drawings.

In the present invention as described above, the receiving end of the digital communication system quantizes a signal whose absolute value of the received signal is greater than or equal to a threshold value, and adjusts a signal-to-noise ratio (SNR) estimation range according to the distribution of the quantized signal, thereby weighting the signal. By applying, there is an effect that can efficiently estimate the quality of the received signal.

In addition, the present invention provides a wider range of signal-to-noise ratio (SNR) by re-adjusting the signal-to-noise ratio (SNR) estimation range according to the distribution of the quantized signal according to the magnitude of the received signal whose magnitude is greater than or equal to the threshold. In this regard, the quality of the received signal can be estimated more accurately.

Claims (20)

An apparatus for estimating a signal-to-noise ratio of a modulated received signal, Signal selecting means for selecting a signal having an absolute value greater than or equal to a threshold for a predetermined number of received signals; Quantization means for storing the signal selected by the signal selection means as a signal of a corresponding range among preset quantization ranges; Symbol number checking means for counting the number of symbols stored in a quantization range preset by said quantization means; Estimation range re-adjustment means for re-adjusting a range to be used for signal-to-noise ratio estimation according to the distribution of the number of symbols confirmed by the symbol number confirmation means; Intermediate value calculating means for calculating a median value for estimating a signal-to-noise ratio by applying weights to the range readjusted by the estimated range readjustment means; And Signal-to-noise ratio estimating means for estimating a signal-to-noise ratio corresponding to the intermediate value calculated by the intermediate value calculating means Apparatus for estimating the signal to noise ratio of the modulated received signal comprising a. The method of claim 1, The received signal in the signal selection means, And a signal received through an I channel and a Q channel, respectively. The method of claim 2, The threshold value of the signal selected by the signal selection means, A signal-to-noise ratio estimation apparatus of a modulated received signal, characterized in that the maximum value of the values mapped to the I channel and the Q channel transmitted. The method of claim 3, wherein The quantization range of the quantization means is, And a signal divided by a predetermined number (Nf) for a signal equal to or greater than a threshold value selected by the signal selecting means. The method according to any one of claims 1 to 4, The estimated range readjustment means, As the number of symbols checked by the symbol number checking means is a value larger than a predetermined value n_min is smaller than the number Nc of a predetermined range, the range of the predetermined range is increased in the order of the number of symbols not selected. An additional range is selected so that the number is selected, and the number of the predetermined range is selected as the range in which the number of symbols checked by the symbol number checking means is greater than a predetermined value n_min is greater than the number Nc of the predetermined range. And an apparatus for estimating a signal-to-noise ratio of a modulated received signal, wherein the adjacent ranges are grouped. The method of claim 5, The number Nc of the predetermined range to be readjusted by the estimated range readjustment means, And a value less than the number of ranges (Nf) quantized by the quantization means. The method of claim 6, The weight of the intermediate value calculating means, A modulated received signal characterized in that the weight is initially set as the estimated range readjustment means selects an additional range, and is an intermediate value of the initially set weights corresponding to the grouped range as the estimated range readjustment means groups the quantization range. Signal to noise ratio estimation device. The method of claim 7, wherein The median value of the intermediate value calculating means is And multiplying the number of symbols in each range re-adjusted by the estimated range readjustment means and a corresponding weight to add a signal-to-noise ratio estimation device of the modulated received signal. The method of claim 8, The signal to noise ratio estimating means, Signal-to-noise ratio (SNR) using a look-up table prepared as a table according to the relationship between the median value for estimating the signal-to-noise ratio calculated by the intermediate value calculation means and the signal-to-noise ratio obtained through several simulations. And estimating a signal-to-noise ratio of the modulated received signal. The method of claim 8, The signal to noise ratio estimating means, Signal-to-noise ratio (SNR) using a circuit implemented by fitting the intermediate value for the signal-to-noise ratio estimation calculated by the intermediate value calculation means and the signal-to-noise ratio obtained through several simulations into a polynomial function. And estimating a signal to noise ratio of the modulated received signal. A signal to noise ratio estimation method of a modulated received signal, A signal selecting step of selecting a signal having an absolute value greater than or equal to a threshold for a predetermined number of received signals; A quantization step of storing the selected signal as a signal having a corresponding range among preset quantization ranges; A symbol number checking step for counting the number of symbols stored in the quantization range; A determination step of determining whether the selected range is greater than or equal to a predetermined number Nc by selecting a range in which the checked number of symbols is greater than a predetermined value n_min; As a result of the determination in the determination step, the additional range is selected so that the predetermined range is less than the predetermined number, and the weight value is applied to the predetermined number range to calculate a median value for estimating the signal-to-noise ratio. An intermediate value calculation step; A second intermediate value calculation step of grouping adjacent ranges according to the determination result of the determination step and calculating a median value for estimating a signal-to-noise ratio by grouping adjacent ranges according to the selected range having a predetermined number or more; And A signal-to-noise ratio estimating step of estimating a signal-to-noise ratio corresponding to the calculated intermediate value Signal to noise ratio estimation method of a modulated received signal comprising a. The method of claim 11, The received signal of the signal selection step, A method for estimating a signal-to-noise ratio of a modulated received signal, characterized in that it is a signal received via an I channel and a Q channel, respectively. The method of claim 12, The threshold of the signal selected in the signal selection step, A method for estimating a signal-to-noise ratio of a modulated received signal, characterized in that the maximum value of the values mapped to the I channel and the Q channel transmitted. The method of claim 13, The quantization range of the quantization step is, The signal-to-noise ratio estimation method of the modulated received signal, characterized in that the range divided by a predetermined number (Nf) for the signal or more selected in the signal selection step. The method of claim 14, The predetermined number Nc is, The signal to noise ratio estimation method of the modulated received signal, characterized in that less than the predetermined number of quantization range (Nf). The method of claim 15, The weight of the first intermediate value calculation step, A method for estimating a signal-to-noise ratio of a modulated received signal, characterized in that the weight is initially set for each quantization range. The method of claim 15, The weight of the second intermediate value calculation step, Method for estimating the signal-to-noise ratio of the modulated received signal, characterized in that the median value of the initially set weight corresponding to the grouped range. The method of claim 17, The intermediate value calculated in the first and second intermediate value calculation step, A method of estimating a signal-to-noise ratio of a modulated received signal, characterized in that the sum of the number of symbols in each range multiplied by a corresponding weight. The method according to any one of claims 11 to 18, The signal to noise ratio estimating step, A signal-to-noise ratio (SNR) is estimated by using a look-up table prepared as a table according to the relationship between the calculated median for estimating the signal-to-noise ratio and the signal-to-noise ratio obtained through several simulations. A signal to noise ratio estimation method of a modulated received signal. The method according to any one of claims 11 to 18, The signal to noise ratio estimating step, The signal-to-noise ratio (SNR) is estimated by using a circuit implemented by fitting the calculated relationship between the intermediate value for the signal-to-noise ratio and the signal-to-noise ratio obtained through several simulations as a polynomial function. A signal to noise ratio estimation method of a modulated received signal.

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