JPH10117160A - Demodulator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the demodulator that conducts fading distortion compensation in which processing time is reduced and power consumption is decreased while keeping the accuracy of the fading distortion compensation. SOLUTION: A fading distortion estimate circuit 31 uses a known symbol such as a pilot symbol from an input signal to estimate a distortion quantity for each data symbol of each subcarrier. A fading distortion compensation circuit 32 uses received data symbols and the distortion estimate estimated by the fading distortion estimate circuit 31 to allow normalizing shift number detection sections 33 to match digits of the data in the unit of blocks including the pilot symbol and to eliminate the distortion of the received data symbol. Thus, the processing time and the power consumption are reduced while keeping the accuracy of fading distortion compensation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a demodulator capable of compensating fading distortion used in digital mobile communications and the like, and more particularly to a demodulator capable of reducing processing time and power consumption while maintaining compensation accuracy at the same level as that of the prior art. The present invention relates to a demodulation device capable of fading distortion compensation that can be reduced.

[0002]

2. Description of the Related Art FIG. 7 is a block diagram showing a configuration of a demodulator including a conventional fading distortion compensator. FIG.
As shown in FIG. 1, a received signal 1 is input to a subcarrier separation circuit 5 for separating multicarriers into subcarriers via a synchronous detection circuit 4 for converting into baseband in-phase component signals 2 and quadrature component signals 3. From the signal separated by the carrier separation circuit 5, a pulse train having no intersymbol interference is extracted through a reception matched filter 6 and input to a fading distortion compensator 7.

A more detailed configuration of the fading distortion compensator 7 is shown in FIG. 8, and the fading distortion compensator 7 will be described below with reference to FIG. That is, the output signal from the reception matched filter 6 in FIG. 7 is separately input to the fading distortion estimation circuit 11 and the fading distortion compensation circuit 12 in FIG. Here, the fading distortion estimation circuit
In step 11, the distortion of each subcarrier is estimated in data symbol units based on the known symbol distortion amount. The distortion estimation value is input to the fading distortion compensation circuit 12, and based on the distortion estimation value from the fading distortion estimation circuit 11,
After the digitization is performed by the normalized shift number detector 13 for each data symbol in the fading distortion compensation circuit 12, the fading distortion is corrected and the fading distortion is removed.

Hereinafter, this conventional example will be described in more detail. The fading distortion estimating circuit 11 performs distortion compensation in the following manner based on the distortion estimation value for each data symbol obtained by performing an interpolation process on the basis of the distortion amount obtained from a known symbol.

The data of the n-th symbol of the first subcarrier of the received baseband signal is expressed by the following equation (1).
Further, when the distortion estimation value of the data symbol at the same time obtained by the fading distortion estimation circuit 11 is represented by a complex notation as in the following equation (2), I1b (n) + jQ1b (n) (Equation 1) Ci1 (n) + jCq1 (n) (Expression 2) In the fading distortion compensating circuit 12, after the digitization is performed in the normalized shift number detecting unit 13, the signal I1c (n) + jQ1c (n) from which the distortion is removed by performing the processing as in the following equation (3) is obtained. Obtainable. I1c (n) + jQ1c (n) = (I1b (n) + jQ1b (n)) / (Ci1 (n) + jCq1 (n)) (Equation 3) When this is further solved, = (I1b ( n) * Ci1 (n) + Q1b (n) * Cq1 (n) + j (-I1b (n) * Cq1 (n) + Q1b (n) * Ci 1 (n))) / (Ci1 (n) ^ 2+ Cq1 (n) ^ 2) (Equation 4)

Therefore, as shown in the above equation (4), using the received data symbol and the distortion estimation value of the data symbol,
After performing digit alignment for each data symbol, distortion compensation can be performed by performing multiplication and division.

[0007]

However, in the above-mentioned conventional fading distortion compensating apparatus, there is a large difference between the magnitudes of the values of all the received data symbols of all the subcarriers due to the change of the received signal level due to the effect of fading. Therefore, when performing operations such as multiplication and division in the process of performing distortion compensation, distortion of all data symbols of all subcarriers is improved in order to eliminate deterioration in accuracy due to cancellation of digits and improve compensation accuracy. In the process of compensating for the above, it is necessary to perform digit-by-data alignment and operation. Therefore, there is a problem that the processing time and the power consumption are both enormous in proportion to the number of subcarriers and the number of data symbols.

The present invention solves the above-mentioned conventional problems. A demodulation device having an excellent fading distortion compensator for reducing processing time and power consumption while maintaining the same level of compensation accuracy as that of the conventional technology. It is intended to provide a device.

[0009]

According to a first aspect of the present invention, there is provided an apparatus for digitizing data required for distortion compensation in units of a block of several symbols before and after a pilot symbol of each subcarrier. And distortion correction means for performing distortion compensation.

According to a second aspect of the present invention, a means for measuring an envelope level in a subcarrier to obtain a fading pitch and a block length of an operation for performing distortion compensation according to the fading pitch are made variable. , N distortion units (N is an integer variable).

According to a third aspect of the present invention, there is provided means for detecting a shift number for normalizing data required for processing of one of a plurality of subcarriers, and the normalization means A distortion correction unit is provided for compensating for distortion of all subcarriers using the normalized shift number obtained by the shift number detection unit.

Further, the invention according to claim 4 of the present invention provides a means for detecting a normalized shift number of data necessary for processing of an in-phase component signal or a quadrature component signal of each subcarrier, and the normalized shift number. The apparatus is provided with distortion correction means for performing distortion compensation of the in-phase component signal and the quadrature component signal using the normalized shift number obtained by the detection means.

As described above, it is possible to shorten the processing time and reduce the power consumption while maintaining the compensation accuracy at the same level as that of the prior art.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION
A demodulation device for a data transmission device using a multicarrier transmission method having a plurality of subcarriers, the demodulation performing fading distortion compensation using pilot symbols periodically inserted into a data symbol sequence in each of the subcarriers In the apparatus, a fading distortion estimating means for calculating an amount of distortion due to fading for each data symbol of each subcarrier from the inserted pilot symbol, and a block of several symbols before and after the pilot symbol of each subcarrier. A demodulation apparatus characterized by comprising a distortion correction means for performing digit compensation in units of units and performing distortion compensation, wherein a distortion compensation process in a distortion compensation unit is compensated for data symbols for which distortion compensation is performed in block units. Is performed to correct the distortion of the data symbol. It is not necessary to perform all of the data normalization shift number detected for necessary to perform, shortening the processing time, also has the effect of making it possible to reduce the power consumption.

According to a second aspect of the present invention, there is provided a demodulation apparatus for a data transmission apparatus using a multi-carrier transmission system having a plurality of subcarriers, wherein each of the subcarriers has a periodicity in a data symbol sequence. A fading distortion estimating means for calculating a fading distortion amount for each data symbol of each subcarrier from an inserted pilot symbol, in a demodulation device for performing fading distortion compensation using a pilot symbol that is sequentially inserted; A demodulator comprising: means for measuring an envelope level in a subcarrier to obtain a fading pitch; and distortion correcting means for performing digit compensation in blocks of N symbols in accordance with the fading pitch to perform distortion compensation. And fading distortion compensation was performed. By making the number of data symbols included in one block of the processing variable according to the difference in the fading pitch, even if the fading pitch is slow, the number of shifts for performing digit alignment for guaranteeing compensation accuracy more than necessary is required. Since the processing is not required and the appropriate number of data symbols per block can be set according to the fading pitch, the processing time can be reduced and the power consumption can be reduced depending on the situation. It has the action of:

According to a third aspect of the present invention, there is provided a demodulation apparatus for a data transmission apparatus using a multicarrier transmission system having a plurality of subcarriers, wherein a period of a data symbol sequence is A demodulation device that performs fading distortion compensation using pilot symbols that have been sequentially inserted, wherein the fading distortion estimating means calculates a distortion amount due to fading for each data symbol of each subcarrier from the inserted pilot symbols; A means for detecting a shift number for normalizing data necessary for compensating for one of the subcarriers, and a normalized shift number obtained by the normalized shift number detecting means. Compensation for the subcarrier used for detection and other subcarriers. A demodulation device comprising distortion correction means, wherein normalization is performed only on one subcarrier among a plurality of subcarriers to perform distortion compensation processing, and the number of shifts used in the calculation at that time Is stored in the memory, and is used for the distortion compensation processing of other subcarriers, so that the processing amount can be significantly reduced in proportion to the number of subcarriers, thereby shortening the processing and reducing power consumption. It is possible to achieve the effect.

According to a fourth aspect of the present invention, there is provided a demodulation apparatus for a data transmission apparatus using a multi-carrier transmission system having a plurality of subcarriers, wherein each of the subcarriers has a periodicity in a data symbol sequence. A fading distortion estimating means for calculating a fading distortion amount for each data symbol of each subcarrier from the inserted pilot symbols, and Means for detecting a shift number for normalizing data necessary for performing distortion compensation on an in-phase component signal or a quadrature component signal of a carrier, and a normalized shift number obtained by the normalized shift number detecting means. Distortion correction that uses the in-phase component signal and the quadrature component signal to compensate for distortion using A demodulation device characterized by having a stage, for example, normalization is performed only on the in-phase component signal to perform distortion compensation processing, and the number of shifts used for the operation at that time is stored in a memory, and Is used for the distortion compensation processing of the orthogonal component signal, the normalization processing can be reduced to half of the conventional example, the processing amount can be reduced, and the processing can be shortened and the power consumption can be reduced. It has the effect that it becomes possible.

FIG. 1 shows an embodiment of the present invention.
This will be described with reference to FIG.

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
It is a block diagram which shows the structure of the fading distortion compensation apparatus in the demodulation apparatus which performs fading distortion compensation of 1st Embodiment. In FIG. 1, a fading distortion estimating circuit 31 is shown.
Is for estimating the amount of distortion for each data symbol of each subcarrier using a known symbol such as a pilot symbol from an input signal. Fading distortion compensation circuit 32
Is a received data symbol and fading distortion estimation circuit 31
The normalized shift number detection unit 33 performs data digit alignment in block units using the distortion estimation value estimated by the above, and then removes distortion of the received data symbol.

The operation of the fading distortion compensator configured as described above will be described with reference to FIG.

Now, consider one subcarrier among a plurality of subcarriers obtained by separating a received signal. Assuming that the subcarriers are arranged in the slot format shown in FIG. 2 (a), fading distortion estimating section 31 performs reception pilot for data at the position of a pilot symbol (known data symbol) included in each subcarrier. The distortion value of the known pilot symbol of the symbol is detected (FIG. 2B).

This process is performed in the same manner for each pilot symbol of each subcarrier to detect a distortion value. Then, by performing interpolation processing based on the detected distortion value, the distortion amounts of all other data symbols are estimated (FIG. 2C).

In FIG. 2D, three symbols before and after each pilot symbol of each subcarrier are set as one block, and data necessary for distortion compensation is normalized on a block basis, and is expressed by the above equation (4). By performing the calculation, distortion compensation is performed and data is reproduced.

As described above, according to the first embodiment of the present invention, the distortion compensation processing in the distortion compensating section 32 is performed by compensating the data symbols for which distortion compensation is performed on a block basis, so that There is no need to detect the number of normalized shifts for all data necessary for performing distortion correction, and it is possible to reduce processing time and reduce power consumption.

(Second Embodiment) FIG. 3 shows a second embodiment of the present invention.
It is a block diagram which shows the structure of the fading distortion compensation apparatus in the demodulation apparatus which performs fading distortion compensation of 1st Embodiment. In FIG. 3, the fading distortion estimating circuit 41 is used.
Is for estimating the amount of distortion for each data symbol of each subcarrier using a known symbol such as a pilot symbol from an input signal. Fading distortion compensation circuit 42
The received data symbol and fading distortion estimation circuit 41
The normalized shift number detection unit 43 performs digit alignment of data in units of N blocks using the distortion estimation value estimated by the above, and then removes the distortion of the received data symbol.

In the fading pitch detection circuit 44, an envelope is detected by an envelope detector, and the envelope level is compared with a preset threshold by a comparator. Is counted by using a counter to determine the fading pitch, and the number of symbols per block (= N) is specified in the subsequent distortion compensation processing.

The operation of the fading distortion compensator configured as described above will be described with reference to FIGS.

The amount of distortion of each data symbol is estimated by the same method as described in the first embodiment.

In the second embodiment, when the distortion is compensated for using the estimated distortion value, the fact that the change in the level of the received signal due to the difference in the fading pitch differs is used. That is, when the fading pitch is fast (FIG. 4 (d1)), the number of data symbols included per block in the processing for performing distortion compensation is reduced, and when the fading pitch is slow (FIG. 4 (d)).
In 2)), distortion compensation processing is performed so that the number of data symbols included in one block is increased.

As described above, according to the second embodiment of the present invention, the number of data symbols included in one block in the process of performing fading distortion compensation is made variable by the difference in fading pitch. Is slow, there is no need to perform a shift number detection process for performing digit alignment to guarantee compensation accuracy more than necessary, and an appropriate number of data symbols per block can be set according to the fading pitch. Therefore, the processing time can be reduced and the power consumption can be reduced depending on the situation.

(Third Embodiment) A fading distortion compensator according to a third embodiment has a basic configuration of the first embodiment.
There is no difference from the fading distortion compensator of the embodiment (FIG. 1).

In this embodiment, the operation of the fading distortion compensating circuit will be described in particular by using the distortion estimation value of each data symbol of each subcarrier detected by the same method as described in the first embodiment. This will be described with reference to FIG.

In FIG. 5, a fading distortion estimating circuit 51 is shown.
Is for estimating the amount of distortion for each data symbol of each subcarrier using a known symbol such as a pilot symbol from an input signal. Fading distortion compensation circuit 52
In the normalized shift number detection unit 53, for example, all the data required for performing distortion compensation on the subcarrier 1 are normalized, and the shift number at that time is stored in a memory. Performs the operation of the above equation (4) shown in the conventional example for each data symbol using the detected shift number.

Here, for data symbols included in subcarriers other than subcarrier 1, distortion compensation processing is performed using the number of shifts obtained when the normalization used when performing distortion compensation for subcarrier 1 is performed. .

As described above, according to the third embodiment of the present invention, distortion compensation is performed by normalizing only one subcarrier among a plurality of subcarriers.
The number of shifts used in the calculation at that time is stored in a memory, and is used for the distortion compensation processing of other subcarriers, so that the processing amount can be significantly reduced in proportion to the number of subcarriers. Processing can be shortened and power consumption can be reduced.

(Fourth Embodiment) A fading distortion compensator according to a fourth embodiment has the basic configuration of the first embodiment.
There is no difference from the fading distortion compensator of the embodiment (FIG. 1).

In this embodiment, the fading distortion compensating circuit among them is used by using the distortion estimation value of each data symbol of each subcarrier detected by the same method as described in the first embodiment. Will be described with reference to FIG.

In FIG. 6, a fading distortion estimating circuit 61 is shown.
Is for estimating the amount of distortion for each data symbol of each subcarrier using a known symbol such as a pilot symbol from an input signal. Fading distortion compensation circuit 62
Performs normalization on data necessary for distortion compensation of the in-phase component signal of the data symbol of each subcarrier in the normalized shift number detection unit 63, and stores the shift number at that time in a memory. For the in-phase component signal, distortion compensation is performed using the normalized data, and subsequently, for the quadrature component signal, distortion compensation is performed using the shift number when the in-phase component signal normalization and distortion compensation are performed.
This process is performed for all data symbols of all subcarriers.

As described above, according to the fourth embodiment of the present invention, the distortion compensation processing is performed by normalizing only the in-phase component signal, and the number of shifts used in the calculation at that time is stored in the memory. By using it for the distortion compensation processing of the orthogonal component signal, the normalization processing can be halved compared to the conventional example, and the processing amount can be reduced, thereby shortening the processing and reducing power consumption. Can be achieved.

[0040]

As is clear from the above-described embodiment, the demodulation apparatus according to the first embodiment of the present invention uses the data necessary for distortion compensation as a block of several symbols before and after the pilot symbol of each subcarrier. A distortion correction unit that performs digit alignment in units and performs distortion compensation. The distortion compensation processing in the distortion compensation unit is performed by compensating the data symbols for which distortion compensation is performed in units of blocks, thereby distorting the data symbols. It is not necessary to detect the number of normalized shifts for all data necessary for performing the correction, and the processing time can be reduced and the power consumption can be reduced.

The demodulator according to the second embodiment of the present invention measures the envelope level of a subcarrier to obtain a fading pitch and the block length of an operation for performing distortion compensation according to the fading pitch. A distortion correction means for performing distortion correction in blocks of N symbols (where N is an integer), which is variable, is provided. The number of data symbols included in one block of the processing for fading distortion compensation is determined by the fading pitch. In this case, even if the fading pitch is slow, there is no need to perform a shift number detection process for performing digit alignment for ensuring compensation accuracy more than necessary. Since the number of data symbols per unit can be set, the processing time can be reduced depending on the situation. , Also an effect that it is possible to reduce power consumption.

Further, the demodulation apparatus according to the third embodiment of the present invention comprises: means for detecting a shift number for normalizing data necessary for processing for one of a plurality of subcarriers; The apparatus is provided with distortion correction means for compensating distortion of all subcarriers using the normalized shift number obtained by the normalized shift number detection means, and for one subcarrier among a plurality of subcarriers. Only normalization is performed and distortion compensation processing is performed, and the number of shifts used in the calculation at that time is stored in a memory, and is used for distortion compensation processing of other subcarriers, whereby processing is performed in proportion to the number of subcarriers. This makes it possible to greatly reduce the amount of data, which leads to an effect that processing can be shortened and power consumption can be reduced.

The demodulating apparatus according to the fourth embodiment of the present invention comprises means for detecting the number of normalized shifts of data necessary for processing the in-phase component signal or the quadrature component signal of each subcarrier, Using the normalized shift number obtained by the normalized shift number detecting means, the distortion correcting means for compensating the distortion of the in-phase component signal and the quadrature component signal. Compensation processing is performed, and the number of shifts used for the operation at that time is stored in a memory, and is used for the distortion compensation processing of the orthogonal component signal, so that the normalization processing can be reduced to half compared with the conventional example. Thus, the processing amount can be reduced, and the processing can be shortened and the power consumption can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a fading distortion compensator in a demodulator according to a first embodiment of the present invention;

FIG. 2 is a diagram for explaining processing performed by a fading distortion compensator in the demodulator according to the first embodiment of the present invention;

FIG. 3 is a block diagram showing a configuration of a fading distortion compensator in a demodulator according to a second embodiment of the present invention;

FIG. 4 is a diagram for explaining processing performed by a fading distortion compensator in a demodulator according to a second embodiment of the present invention;

FIG. 5 is a block diagram showing a configuration of a fading distortion compensator in a demodulator according to a third embodiment of the present invention;

FIG. 6 is a block diagram showing a configuration of a fading distortion compensator in a demodulator according to a fourth embodiment of the present invention;

FIG. 7 is a block diagram showing a configuration of a conventional demodulator that performs fading distortion compensation;

FIG. 8 is a block diagram of a fading distortion compensator in a conventional demodulator.

[Explanation of symbols]

 Reference Signs List 1 received signal 2 in-phase component signal 3 quadrature component signal 4 synchronous detection circuit 5 subcarrier separation circuit 6 matched filter 7 fading distortion compensator 11, 31, 41, 51, 61 fading distortion estimating circuit 12, 32, 42, 52, 62 Fading distortion compensation circuit 13, 33, 43, 53, 63 Normalized shift number detector 44 Fading pitch detector

Claims (4)

[Claims] 1. A demodulation device for a data transmission device using a multicarrier transmission method having a plurality of subcarriers, wherein fading is performed using pilot symbols periodically inserted into a data symbol sequence in each of the subcarriers. In a demodulation device for performing distortion compensation, a fading distortion estimating means for calculating an amount of distortion due to fading for each data symbol of each subcarrier from an inserted pilot symbol, and data necessary for distortion compensation by a pilot symbol of each subcarrier. A demodulation device comprising a distortion correcting unit for performing digit compensation in units of blocks of several symbols before and after and performing distortion compensation. 2. A demodulation device for a data transmission device using a multicarrier transmission method having a plurality of subcarriers, wherein fading is performed using pilot symbols periodically inserted in a data symbol sequence in each of the subcarriers. In a demodulator for performing distortion compensation, a fading distortion estimating means for calculating an amount of distortion due to fading for each data symbol of each subcarrier from an inserted pilot symbol, and fading by measuring an envelope level in each of the subcarriers A demodulation device comprising: means for calculating a pitch; and distortion correction means for performing distortion compensation by performing digit alignment in block units of N symbols (N is an integer) according to a fading pitch. 3. A demodulator for a data transmission apparatus using a multicarrier transmission method having a plurality of subcarriers, wherein fading is performed using pilot symbols periodically inserted in a data symbol sequence in each of the subcarriers. In a demodulation device for performing distortion compensation, a fading distortion estimating means for calculating an amount of distortion due to fading for each data symbol of each subcarrier from an inserted pilot symbol, and distortion compensation for one of the plurality of subcarriers. Means for detecting the number of shifts for normalizing the data necessary for performing the above, and distortion compensation for all subcarriers is performed using the normalized number of shifts obtained by the normalized number of shifts detecting means. A demodulator comprising distortion correction means. 4. A demodulation device for a data transmission device using a multicarrier transmission system having a plurality of subcarriers, wherein fading is performed using pilot symbols periodically inserted in a data symbol sequence in each of the subcarriers. In a demodulation device that performs distortion compensation, a fading distortion estimating unit that calculates an amount of distortion due to fading for each data symbol of each subcarrier from an inserted pilot symbol, and an in-phase component signal or a quadrature component signal of each subcarrier. Using a means for detecting a normalized shift number for each data symbol, and a normalized shift number obtained by the normalized shift number detection means,
A demodulation device comprising a distortion correcting means for compensating distortion of an in-phase component signal and a quadrature component signal.