JP3444805B2 - Modulation accuracy measurement circuit - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a modulation accuracy measuring circuit for testing communication terminals, and more particularly, to a code error rate of a transmitter even when the amount of deterioration of the code error rate due to phase noise is large. The present invention relates to a modulation accuracy measuring circuit capable of measuring a modulation error for determining an appropriate modulation accuracy specified value with respect to an allowable deterioration amount.

[0002]

2. Description of the Related Art Each device constituting a transmitter has a deterioration factor which deteriorates the quality of a transmission signal. Due to these deterioration factors, the transmission signal causes a phase error which is a deviation in the phase direction from the ideal signal point and an amplitude error which is a deviation in the amplitude direction. That is, a modulation error occurs. On the other hand, as a result of deterioration of the quality of the transmission signal due to the above deterioration factors, deterioration of the code error rate occurs.

However, in reality, since the receiver also has a deterioration factor, it is impossible to measure only the deterioration amount of the code error rate due to the deterioration factor of the transmitter. Therefore, it is necessary to define the modulation accuracy in order to suppress the deterioration amount of the code error rate due to the deterioration factor of the transmitter to be less than the allowable value.

Modulation accuracy is specified in various systems, but a method of defining the modulation accuracy using a measured value of the modulation error representing the amount of error of the transmission signal from the ideal signal point is often used. . In practice, a modulation accuracy measurement circuit is used to measure the modulation error of the modulation signal output from the transmitter.

FIG. 10 shows a configuration example of a conventional modulation accuracy measuring circuit for correcting a phase error. In the figure, the reception signal A (t) received by the reception circuit 1 is the signal extraction circuit 2
And to the phase rotation circuit 3. Signal extraction circuit 2
Is N used to estimate the phase error amount from the demodulated signal A (t).
A phase error amount estimation signal P (t) consisting of (N ≧ 1, N: integer) signals is extracted.

The phase error amount estimation signal P (t) output from the signal extraction circuit 2 is input to the signal holding circuit 4 in order to collect a number of phase error amount estimation signals suitable for phase error amount estimation. . In the signal holding circuit 4, the phase error estimation signal P
(T) is held by the number M of sets (M ≧ 1, M: integer) suitable for estimating the phase error amount extracted in a certain period.

In the phase error detection circuit 5, the signal holding circuit 4
The phase error amount is detected using the phase error estimation signal group Q (t) composed of the M sets of phase error estimation signals P (t) held in. In the phase rotation circuit 3, the received signal A by the phase error amount detected by the phase error detection circuit 5 is received.
By rotating the phase of (t) in the reverse direction, the phase error can be corrected with high accuracy. The signal B (t) output from the phase rotation circuit 3 is input to the signal accuracy measurement circuit 6 and the modulation error is measured.

[0008]

In order to define the modulation accuracy by using the modulation error, the relationship between the deterioration amount of the code error rate due to the deterioration factor of the transmitter and the modulation error must be 1: 1. There is. Therefore, when there is a single deterioration factor, the relationship between the modulation error measured by the conventional modulation accuracy measurement circuit and the deterioration amount of the code error rate caused by the deterioration factor of the transmitter is compared with various deterioration factors. View.

Then, in a region where the code error rate is largely deteriorated, a deterioration factor that causes only a phase error like phase noise is the same code error as other deterioration factors that cause both a phase error and a vibration error. A small modulation error is taken with respect to the rate deterioration amount. From this, it can be seen that even in a system in which the deterioration amount of the code error rate is the same, the value of the modulation error changes greatly if the combination of the deterioration factors is different.

Therefore, when the amount of deterioration of the code error rate due to the phase noise is large, there is a problem in that it is not possible to determine an appropriate modulation accuracy specified value for the allowable amount of deterioration of the code error rate of the transmitter. It is an object of the present invention to provide a modulation accuracy measuring circuit that measures a modulation error so that the modulation accuracy can be defined even when the deterioration amount of the code error rate due to the phase noise is large. . .

[0011]

According to the invention, the aforesaid problems are solved by the means defined in the claims. That is, the invention of claim 1 is the first receiving means for receiving a signal whose phase error amount changes with the passage of time, and N (N ≧ 1) for estimating the phase error amount from the output signal of the receiving means. , N: integer) first signal extracting means for extracting signals,

A set number N of phase error amount estimation signals extracted by the first signal extraction means is suitable for phase error amount estimation included in a fixed period M (M ≧ 1, M: integer) The first signal holding means for holding only the signal and the M sets of phase error amount estimation signals held in the first signal holding means
(L ≧ 1, L: integer) pairs, first storage means for performing a shift register type operation with a tap number L to be stored,

M × L stored in the first storage means
A first phase error amount detecting means for detecting a smoothed phase error amount calculated from a pair of phase error amount estimating signals; and a phase error amount detected by the first phase error amount detecting means. A modulation accuracy measuring circuit comprising first phase rotating means for rotating the phase of a received signal in reverse, and first signal accuracy measuring means for measuring a modulation error of an output signal of the first phase rotating means.

According to a second aspect of the present invention, in the modulation precision measuring circuit according to the first aspect, the first signal precision measuring means is a vector which is an effective value of an error from the normal position of the input signal on the phase plane. It is configured to measure the error.

According to a third aspect of the invention, a plurality of second receiving means for receiving a multi-carrier signal whose phase error amount changes with the passage of time, and estimation of the phase error amount from the output signals of the second receiving means. Second signal extracting means for extracting N (N ≧ 1, N: integer) signals for

A set of N phase error amount estimation signals extracted by the second signal extracting means is set in a number M (M ≧ l, M: integer) suitable for phase error amount estimation included in a certain period. ) Is further held, and M sets of phase error amount estimation signals held in the second signal holding means are further L
(L ≧ 1, L: integer) a second storage means for performing a shift register type operation with the number of taps L to be stored.

M × stored in the second storage means
Second phase error amount detecting means for detecting a smoothed phase error amount calculated from the L sets of phase error amount estimation signals;
Second phase rotating means for rotating the phase of the received signal in reverse by the phase error amount detected by the second phase error amount detecting means, and measuring the modulation error of the output signal of the second phase rotating means. A modulation accuracy measuring circuit including a signal accuracy measuring means.

According to a fourth aspect of the present invention, in the modulation precision measuring circuit according to the third aspect, the second signal precision measuring means is a vector which is an effective value of an error from the normal position of the input signal on the phase plane. It is configured to measure the error.

According to a fifth aspect of the present invention, a third receiving means for receiving a multicarrier signal whose phase error amount changes with the passage of time, and a multicarrier signal output from the third receiving means are demultiplexed. Demultiplexing means for outputting a subcarrier signal, first signal selecting means for extracting an effective subcarrier signal from the output of the demultiplexing means, and estimation of the phase error amount from the output signal of the first signal selecting means For N (N ≧
Second signal extraction means for extracting (1, N: integer) signals,

A set number N of phase error amount estimation signals extracted by the second signal extraction means is suitable for phase error amount estimation included in a certain period M (M ≧ 1, M: integer) L for holding the second signal holding means for holding only the signal and the M sets of phase error amount estimation signals held in the second signal holding means.
(L ≧ 1, L: integer) pairs, and second storage means for performing a shift register type operation with the number of taps L to be stored,

M × L stored in the second storage means
A second phase error amount detecting means for detecting a smoothed phase error amount calculated from a set of phase error amount estimating signals; and a phase error amount detected by the second phase error amount detecting means. A modulation accuracy measuring circuit comprising second phase rotating means for rotating the phase of a received signal in reverse, and second signal accuracy measuring means for measuring a modulation error of an output signal of the second phase rotating means.

According to a sixth aspect of the present invention, in the modulation precision measuring circuit according to the fifth aspect, the second signal precision measuring means is a vector which is an effective value of an error from the normal position of the input signal on the phase plane. It is configured to measure the error.

According to a seventh aspect of the present invention, there is provided a fourth receiving means for receiving an OFDM signal whose phase error amount changes with the passage of time, and a freeer for demultiplexing the output signal of the fourth receiving means. A conversion operation means, a second signal selection means for extracting an effective non-multiplexed signal from the output of the Fourier transform operation means, and an estimation of the phase error amount from the output signal of the second signal selection means. Second signal extraction means for extracting N (N ≧ 1, N: integer) signals;

A set number N of phase error amount estimation signals extracted by the second signal extraction means is suitable for phase error amount estimation included in a fixed period M (M ≧ 1, M: integer) The second signal holding means for holding only the signal and the M sets of phase error amount estimation signals held in the second signal holding means
(L ≧ 1, L: integer) pairs, and second storage means for performing a shift register type operation with the number of taps L to be stored,

M × L stored in the second storage means
A second phase error amount detecting means for detecting a smoothed phase error amount calculated from a set of phase error amount estimating signals; and a phase error amount detected by the second phase error amount detecting means. A modulation accuracy measuring circuit comprising second phase rotating means for rotating the phase of a received signal in reverse, and second signal accuracy measuring means for measuring a modulation error of an output signal of the second phase rotating means.

According to an eighth aspect of the present invention, in the modulation precision measuring circuit according to the seventh aspect, the second signal precision measuring means is a vector which is an effective value of an error from the normal position of the input signal on the phase plane. It is configured to measure the error.

The vector error when the phase noise is present alone is smaller than the vector error when the deterioration amount of the code error rate due to other deterioration factors is equal. Paying attention to this point, the modulation accuracy measuring circuit of the present invention includes a plurality of phase error estimation signal groups Q (t) including the phase error estimation signal P (t) by the number M of sets suitable for phase error estimation. The phase error calculated from the smoothed signal is corrected.

As a result, the curve showing the relationship between the deterioration amount of the code error rate and the modulation error when the phase noise is present alone becomes the same as that of the other deterioration factors. Therefore, the relationship between the amount of deterioration of the code error rate caused by the deterioration factor of the transmitter and the modulation error is one to one. Therefore, the modulation accuracy can be defined using the modulation error measured by the modulation accuracy measurement circuit of the present invention.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a first embodiment of the modulation accuracy measuring circuit of the present invention. This embodiment is claim 1.
It corresponds to the invention of. In the figure, the receiving circuit 1, the signal extracting circuit 2, the phase rotating circuit 3, the signal holding circuit 4, and the signal accuracy measuring circuit 6 have the same functions as those of the conventional configuration shown in FIG.

The feature of this embodiment is that the storage circuit 7 and the phase error detection circuit 8 are provided as means for detecting the phase error amount smoothed over a plurality of sets of phase error estimation signal groups Q (t). It is in. That is, unlike the conventional circuit that estimates the phase error using the phase error amount estimation signal group Q (t), the L sets of phase error estimation signal group Q (t) stored in the storage circuit 8 are stored. Since the phase detection is performed using the phase error, the phase error is smoothed and the modulation error amount caused by the phase noise is increased.

Received signal A output from the receiving circuit 1
(T) is input to the signal extraction circuit 2 and the phase rotation circuit 3. The signal extraction circuit 2 extracts N signals for phase error estimation from the received signal A (t). A set of N phase error amount estimation signals P extracted by the signal extraction circuit 2
(T) is input to the signal holding circuit 4.

The signal holding circuit 4 holds the phase error amount estimation signal P (t) by the number M of sets suitable for the phase error amount estimation. These M sets of phase error amount estimation signals are referred to as a phase error amount estimation signal group Q (t), and in the conventional circuit, the phase error estimation signal group Q (t) is a set of signals suitable for estimating the phase error amount. If so, it was used to estimate the amount of phase error.

However, in the circuit of the present invention, the storage circuit 7 is further used to store only L sets of the phase error estimation signal group Q (t) output from the signal holding circuit 4. The phase error detection circuit 8 detects the smoothed phase error amount over the L sets of phase error correction signal groups Q (t) stored in the storage circuit 7.

The phase rotation circuit 3 reversely rotates the phase of the received signal A (t) by the phase error amount detected by the phase error detection circuit 8. The signal accuracy measuring circuit 6 measures the modulation error of the signal C (t) in which the smoothed phase error amount is corrected over the L sets of phase estimation signal groups Q (t).

FIG. 2 shows a second embodiment of the modulation accuracy measuring circuit of the present invention. This embodiment corresponds to the invention of claim 2. In the figure, the receiving circuit 1, the signal extracting circuit 2, the phase rotating circuit 3, the signal holding circuit 4, the memory circuit 7, and the phase error detecting circuit 8 are the same as those in the first embodiment of FIG. 1 described above. Since it has the function of, the description is omitted.

In this example, in the phase rotation circuit 3, L
The signal C (t), which has been subjected to the correction of the phase error amount smoothed over the set of phase error signal groups Q (t), is input to the vector error measuring circuit 9 and the vector error is measured.

FIG. 3 shows a third embodiment of the modulation accuracy measuring circuit of the present invention. This embodiment corresponds to the invention of claim 3. Here, the modulated signal is assumed to be a multicarrier signal. In the figure, the signal extraction circuit 11, the phase rotation circuit 12, and the signal accuracy measurement circuit 16 correspond to multi-carriers, and signals are input in parallel.

Further, the phase rotation circuit is so constructed as to output in parallel as many as the number of inputs. The feature of the present embodiment is that the storage circuit 1 is provided as means for detecting the smoothed phase error amount over a plurality of sets of phase error estimation signal groups S (t).
4 and the phase error detection circuit 15 are provided.

That is, the phase error amount estimation signal group S
Unlike the conventional circuit in which the phase error is estimated by using (t), the phase error is detected by using the L sets of phase error estimation signal groups S (t) stored in the storage circuit 14. Are smoothed to increase the amount of modulation error caused by phase noise.

A plurality of receiving circuits 10-1 to 10-K (K>
The received signal D (t) output from (1, K: integer) is input to the signal extraction circuit 11 and the phase rotation circuit 12.
The signal extraction circuit 11 extracts N signals for phase error estimation from the received signal D (t).

A set of N phase error estimation signals R (t) extracted by the signal extraction circuit are input to the signal holding circuit 13. The signal holding circuit 13 holds the phase error amount estimation signal R (t) by the number M of sets suitable for the phase error amount estimation. These M sets of phase error amount estimation signals are used as the phase error amount estimation signal group S (t), and in the conventional circuit, the phase error estimation signal group S (t) is a set of signals suitable for estimating the phase error amount. And used for estimating the phase error amount.

However, in the circuit of the present invention, the storage circuit 14 is further used to store only L sets of the phase error estimation signal group S (t) output from the signal holding circuit 13. The phase error detection circuit 15 detects the smoothed phase error amount over the L sets of phase error correction signal groups S (t) stored in the storage circuit 14.

The phase rotation circuit 12 reversely rotates the phase of the received signal D (t) by the phase error amount detected by the phase error amount detection circuit 15. The signal accuracy measuring circuit 16 measures the modulation error of the signal E (t) in which the smoothed phase error amount is corrected over the L sets of phase error estimation signal groups S (t).

FIG. 4 is a diagram showing a fourth embodiment of the modulation accuracy measuring circuit of the present invention. This embodiment corresponds to the invention of claim 4. In the figure, the receiving circuit 10-1
-10-K, signal extraction circuit 11, phase rotation circuit 12, signal holding circuit 13, storage circuit 14, phase error detection circuit 15
Has the same function as in the case of the third embodiment shown in FIG. 3 described above, and a description thereof will be omitted.

In the phase rotation circuit 12, the signal E (t) corrected by the amount of phase error smoothed over the L sets of phase error signal groups S (t) is input to the vector error measuring circuit 17 to generate a vector. Error measurements are taken.

FIG. 5 is a diagram showing a fifth embodiment of the modulation accuracy measuring circuit of the present invention. This embodiment corresponds to the invention of claim 5. Here, the modulated signal is assumed to be a multicarrier signal. In the figure, the signal extraction circuit 1
1, the phase rotation circuit 12, and the signal accuracy measurement circuit 16 are compatible with multi-carriers and have a configuration in which signals are input in parallel.

Further, the phase rotation circuit is so constructed as to output in parallel with the number of inputs. The feature of the present embodiment is that the storage circuit 1 is provided as means for detecting the phase error amount smoothed over a plurality of sets of phase error estimation signal groups U (t).
4 and the phase error detection circuit 15 are provided.

That is, the phase error amount estimation signal group U
Unlike the conventional circuit in which the phase error is estimated by using (t), the phase error is detected by using the L sets of phase error estimation signal groups U (t) stored in the storage circuit 14. Are smoothed to increase the amount of modulation error caused by phase noise.

The received signal output from the receiving circuit 18 is
The demultiplexing circuit 19 releases the multiplexing. The signal selection circuit 20 selects a valid signal from the demultiplexed signals output from the demultiplexing circuit 19. Signal selection circuit 20
The signal F (t) output from is input to the signal extraction circuit 11 and the phase rotation circuit 12.

The signal extraction circuit 11 extracts N signals for phase error estimation from the received signal F (t). A set of N phase error amount estimation signals T (t) extracted by the signal extraction circuit 11 is input to the signal holding circuit 13. The signal holding circuit 13 holds the phase error amount estimation signal T (t) by the number M of sets suitable for the phase error amount estimation.

These M sets of phase error amount estimation signals are used as a phase error amount estimation signal group U (t), and in the conventional circuit, the phase error estimation signal group U (t) is a signal suitable for estimating the phase error amount. It was used to estimate the amount of phase error.
However, in the circuit of the present invention, only L sets of the phase error estimation signal group U (t) output from the signal holding circuit 13 are further stored by using the storage circuit 14.

The phase error detection circuit 15 detects the smoothed phase error amount over the L sets of phase error correction signal groups U (t) stored in the storage circuit 14. The phase rotation circuit 12 reversely rotates the phase of the reception signal F (t) by the phase error amount detected by the phase error amount detection circuit 15. In the signal accuracy measurement circuit 16, L sets of phase error estimation signal groups U
The modulation error of the signal G (t) corrected for the amount of phase error smoothed over (t) is measured.

FIG. 6 is a diagram showing a sixth embodiment of the modulation accuracy measuring circuit of the present invention. This embodiment corresponds to the invention of claim 6. The signal extraction circuit 11, the phase rotation circuit 12, the signal holding circuit 13, the storage circuit 14, the phase error detection circuit 15, the reception circuit 18, the demultiplexing circuit 19, and the signal selection circuit 20 are the fifth described in FIG. Since it has the same function as that of the above embodiment, the description thereof will be omitted. Phase rotation circuit 12
, The signal G corrected for the phase error amount smoothed over the L sets of phase error estimation signal groups U (t)
(T) is input to the vector error measuring circuit 17, and the vector error is measured.

FIG. 7 is a diagram showing a seventh embodiment of the modulation accuracy measuring circuit of the present invention. This embodiment corresponds to the invention of claim 7. Here, the modulated signal is assumed to be an OFDM signal. In the figure, the signal extraction circuit 11, the phase rotation circuit 12, and the signal accuracy measurement circuit 16 are configured to input signals in parallel.

Further, the phase rotation circuit is constructed so as to output signals in parallel as many as the number of inputs. The feature of the present embodiment is that as means for detecting the amount of phase and phase error smoothed over a plurality of sets of phase error estimation signal groups Q (t),
The storage circuit 14 and the phase error detection circuit 15 are provided.

That is, the phase error amount estimation signal group W
Unlike the conventional circuit in which the phase error is estimated by using (t), the phase error is detected by using the L sets of phase error estimation signal groups W (t) stored in the storage circuit 14. Are smoothed to increase the amount of modulation error caused by phase noise.

The received signal output from the receiving circuit 21 is
The Fourier transform operation circuit 22 releases the multiplexing.
The signal selection means 20 selects a valid signal from the demultiplexed signals output from the Fourier transform operation circuit 22. The signal H (t) output from the signal selection circuit 20
Is input to the signal extraction circuit 11 and the phase rotation circuit 12.

The signal extraction circuit 11 extracts N signals for phase error estimation from the received signal H (t). The set of N phase error amount estimation signals V (t) extracted by the signal extraction circuit 11 is input to the signal holding circuit 13. The signal holding circuit 13 holds the phase error amount estimation signal V (t) by the number M of sets suitable for the phase error amount estimation.

These M sets of phase error amount estimation signals are used as the phase error amount estimation signal group W (t), and in the conventional circuit, the phase error estimation signal group W (t) is a signal suitable for estimating the phase error amount. It was used to estimate the amount of phase error.
However, in the circuit of the present invention, only L sets of the phase error estimation signal group W (t) output from the signal holding circuit 13 are further stored by using the storage circuit 14.

The phase error detection circuit 15 detects the smoothed phase error amount over the L sets of phase error correction signal groups W (t) stored in the storage circuit 14. The phase rotation circuit 12 reversely rotates the phase of the reception signal H (t) by the phase error amount detected by the phase error amount detection circuit 15. In the signal accuracy measuring circuit 16, L sets of estimated signal groups for phase error W
The modulation error of the signal I (t) corrected for the amount of phase error smoothed over (t) is measured.

FIG. 8 is a diagram showing an eighth embodiment of the modulation accuracy measuring circuit of the present invention. This embodiment corresponds to the invention of claim 8. In the figure, the signal extraction circuit 1
1, phase rotation circuit 12, signal holding circuit 13, storage circuit 1
4, the phase error detection circuit 15, the signal selection circuit 20, the reception circuit 21, and the Fourier transform circuit 22 have the same functions as those of the seventh embodiment shown in FIG.

In the phase rotation circuit 12, the signal I (t) corrected by the phase error amount smoothed over the L sets of phase error estimation signal groups W (t) is input to the vector error measurement circuit 17, Vector error measurements are made.

FIG. 9 is a diagram showing the relationship between the modulation error measured by the modulation accuracy measuring circuit by computer simulation and the deterioration amount of the code error rate. The vector error and the equivalent CNR deterioration amount at a packet error rate of 10% were used to represent the deterioration amount of the modulation error and the code error rate, respectively.

In the figure, the vertical axis indicates the packet error rate of 10.
The equivalent CNR deterioration amount in%, and the horizontal axis is the effective value of the vector error. The white squares in the figure represent the case of the circuit of the present invention (the number of OFDM symbols used for phase error estimation: 5).
Also, the black circles indicate the conventional circuit (OF used for phase error estimation.
The number of DM symbols is 1).

Note that this simulation is calculated in the AWGN environment in the eighth embodiment. The calculation conditions are a transmission rate of 24 Mbit / s, a modulation / demodulation method of 16 QAM-QFDM / coherent detection, and a number of subcarriers of 4
8, the number of IFFT points is 64, the guard interval is 800 ns, the packet length is 1000 bytes, and the error correction is convolutional code with constraint length 7 and 3-bit soft decision Viterbi decoding.

The deterioration factors considered are phase noise, non-linear distortion of high-power amplifier, quadrature phase error and quadrature amplitude ratio error generated in the quadrature modulator, IFFT internal operation quantization error, DA
C quantization error. The above deterioration factors were simulated within the range of easily realizable parameters.

It is assumed that the phase error estimation signal is inserted at the 3rd 26th 46th counting from the subcarrier having the lower frequency among the 48 subcarriers. The phase error is calculated by performing vector addition of the extracted signals and subtracting the phase when there is no phase error from the calculated phase of the signal.

At the receiver, in order to reduce the effect of thermal noise, 2
After correcting the phase error using the six phase error amount estimation signals extracted from the 0FDM symbol, the code error rate is obtained from the demodulated signal. Further, since the modulation accuracy measuring circuit can receive the transmission signal without power attenuation, thermal noise can be ignored.

Therefore, the conventional circuit is a circuit configured to perform phase error estimation using three phase error amount estimation signals extracted from one OFDM symbol. On the other hand, the circuit of the present invention is a circuit configured to estimate the phase error using 15 phase error amount estimation signals extracted from 50 FDM symbols. Vector error and equivalent CN in the conventional circuit configuration
It can be seen that the relationship between the R deterioration amounts is not 1: 1.

For example, the variation of the equivalent CNR deterioration amount when the vector error takes a value of 10% is 0.5 dB or more. In the modulation accuracy measuring circuit of the present invention,
The vector error measured after the phase error of the received signal is corrected using the 15 phase error estimation signals included in the FDM symbol has a relationship of approximately 1: 1 with the equivalent CNR deterioration amount. Was confirmed.

As a result, the equivalent CNR resulting from the phase noise is
It has been clarified that the modulation accuracy can be defined by using the vector error measured by the circuit of the present invention even in the system having a large deterioration amount.

[0072]

As described above, the modulation error measured by the modulation accuracy measuring circuit of the present invention is caused by the phase noise which is difficult to be defined by the modulation error measured by the conventional modulation accuracy measuring circuit. It is possible to specify the modulation accuracy even in a system in which the deterioration amount of the code error rate is large. Also,
By measuring the modulation error using the modulation accuracy measuring circuit of the present invention, there is also an advantage that the accurate deterioration amount can be easily known when designing and improving the transmitter.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of a modulation accuracy measuring circuit of the present invention.

FIG. 2 is a block diagram showing a second embodiment of a modulation accuracy measuring circuit of the present invention.

FIG. 3 is a block diagram showing a third embodiment of the modulation accuracy measurement circuit of the present invention.

FIG. 4 is a block diagram showing a fourth embodiment of the modulation accuracy measurement circuit of the present invention.

FIG. 5 is a block diagram showing a fifth embodiment of the modulation accuracy measurement circuit of the present invention.

FIG. 6 is a block diagram showing a sixth embodiment of the modulation accuracy measuring circuit of the present invention.

FIG. 7 is a block diagram showing a seventh embodiment of the modulation accuracy measurement circuit of the present invention.

FIG. 8 is a block diagram showing an eighth embodiment of the modulation accuracy measurement circuit of the present invention.

FIG. 9 is a diagram showing a relationship between an equivalent CNR deterioration amount and a vector error by computer simulation.

FIG. 10 is a block diagram showing a configuration example of a conventional modulation accuracy measurement circuit.

[Explanation of symbols]

1,10,18,21 Receiver circuit 2,11 Signal extraction circuit 3,12 Phase rotation circuit 4,13 Signal holding circuit 5,8,15 Phase error detection circuit 6,16 Signal accuracy measurement circuit 7,14 Memory circuit 9,17 Vector error measurement circuit 19 demultiplexing circuit 20 signal selection circuit 22 Fourier transform operation circuit

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masahiro Morikura 3-19-2 Nishishinjuku, Shinjuku-ku, Tokyo Nihon Telegraph and Telephone Corporation (56) Reference JP-A-11-331299 (JP, A) JP-A-7-297859 (JP, A) JP-A-10-23086 (JP, A) Satoshi Hori, Tomoaki Kumagai, Tohru Sakata, Masahiro Morizou, Study on modulation accuracy determination in OFDM system, IEICE Technical Research Report, January 21, 1999, SAT98-68, Vol. 98, No. 535, P.I. 15-20 (58) Fields investigated (Int.Cl. ⁷ , DB name) H04L 27/22 H04J 1/00 H04J 11/00

Claims (8)

(57) [Claims] 1. A first receiving means for receiving a signal whose phase error amount changes with the passage of time, and N for estimating the amount of phase error from an output signal of said receiving means.
First signal extraction means for extracting (N ≧ 1, N: integer) signals, and a set of N phase error amount estimation signals extracted by the first signal extraction means are included in a certain period. For holding the number of sets M (M ≧ 1, M: integer) suitable for estimating the phase error amount, and for estimating the M sets of phase error amounts held by the first signal holding unit A first storage unit that performs a shift register type operation with a tap number L for further storing L (L ≧ 1, L: integer) sets of signals, and M × L sets stored in the first storage unit. First phase error amount detecting means for detecting a smoothed phase error amount calculated from the phase error amount estimating signal, and the received signal by the phase error amount detected by the first phase error amount detecting means. Of the output signal of the first phase rotation means for rotating the phase of the first phase rotation means in reverse. A modulation accuracy measuring circuit, comprising: first signal accuracy measuring means for measuring a tonal error. 2. The modulation accuracy measuring circuit according to claim 1, wherein the first signal accuracy measuring means is configured to measure a vector error which is an effective value of an error of an input signal from a normal position on a phase plane. 3. A plurality of second receiving means for receiving a multi-carrier signal whose phase error amount changes over time, and N (for estimating the phase error amount from the output signal of the second receiving means. N ≧ l, N: integer) second signal extracting means for extracting signals and a set of N phase error amount estimation signals extracted by the second signal extracting means are included in a certain period. Second signal holding means for holding the number M of sets (M ≧ 1, M: an integer) suitable for estimating the phase error amount, and M sets of phase error amount estimation held by the second signal holding means Second storage means for performing a shift register type operation with the number of taps L for further storing L (L ≧ 1, L: integer) sets of signals, and M × L sets stored in the second storage means The second phase that detects the smoothed phase error amount calculated from the phase error amount estimation signal of Error amount detecting means, second phase rotating means for rotating the phase of the received signal in reverse by the phase error amount detected by the second phase error amount detecting means, and output signal of the second phase rotating means And a second signal accuracy measuring means for measuring the modulation error of the modulation accuracy measuring circuit. 4. The modulation accuracy measuring circuit according to claim 3, wherein the second signal accuracy measuring means is configured to measure a vector error which is an effective value of an error of the input signal from the normal position on the phase plane. 5. A third receiving means for receiving a multi-carrier signal whose phase error amount changes with time, a demultiplexing means for demultiplexing an output signal of the third receiving means, and the demultiplexing. First signal selecting means for extracting an effective signal from the output of the means, and N (N ≧ 1, N: integer) signals for estimating the phase error amount from the output signal of the first signal selecting means. A second signal extracting means for extracting, and a set number N (M) of sets of phase error amount estimation signals extracted by the second signal extracting means suitable for phase error amount estimation included in a certain period. Second signal holding means for holding only (≧ 1, M: integer) and M sets of phase error amount estimation signals held in the second signal holding means are further L (L ≧ 1, L: integer) A second storage unit that performs a shift register type operation with the number of taps L to be stored as a set; Second phase error amount detecting means for detecting a smoothed phase error amount calculated from M × L sets of phase error amount estimation signals stored in the storing means, and the second phase error amount detecting means Second phase rotating means for rotating the phase of the received signal in reverse by the amount of phase error detected by the means, and second signal accuracy measuring means for measuring the modulation error of the output signal of the second phase rotating means. A modulation accuracy measuring circuit comprising: 6. The modulation accuracy measuring circuit according to claim 5, wherein the second signal accuracy measuring means is configured to measure a vector error which is an effective value of an error of the input signal from the normal position on the phase plane. 7. A fourth receiving means for receiving an OFDM signal whose phase error amount changes with the passage of time, and a Fourier transform computing means for demultiplexing the output signal of the fourth receiving means. Second signal selecting means for extracting an effective non-multiplexed signal from the output of the Fourier transform computing means, and N (N ≧ 1) for estimating the phase error amount from the output signal of the second signal selecting means. , N: integer) second signal extracting means for extracting signals, and a set of N phase error amount estimation signals extracted by the second signal extracting means for the phase error amount included in a certain period. The second signal holding unit holds only the number M of sets (M ≧ 1, M: an integer) suitable for estimation, and the M sets of phase error amount estimation signals held in the second signal holding unit, Shift register type operation with the number of taps L to store L (L ≧ 1, L: integer) pairs Second storage means for performing, and a second phase error amount for detecting a smoothed phase error amount calculated from M × L sets of phase error amount estimation signals stored in the second storage means. Detecting means, second phase rotating means for rotating the phase of the received signal in reverse by the phase error amount detected by the second phase error amount detecting means, and modulation of the output signal of the second phase rotating means. A modulation accuracy measuring circuit, comprising: a second signal accuracy measuring means for measuring an error. 8. The modulation accuracy measuring circuit according to claim 7, wherein the second signal accuracy measuring means is configured to measure a vector error which is an effective value of an error of the input signal from the normal position on the phase plane.