JP2000228657A - Receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct the phase and amplitude of a received signal without deteriorating an error rate characteristic by providing a weighting means, etc., which multiplies a received symbol after correction by amplitude value when received in a preceding stage where the received symbol after correction is converted into bit data by a quantizing means. SOLUTION: An FFT part 104 performs FFT processing of each subcarrier. A received signal after the FFT processing is subjected to synchronous detection processing in a synchronous detection circuit 105 and effects of phase rotation and amplitude fluctuation due to fading, etc., are eliminated. A level calculator 106 also calculates the receiving level of the received signal. The received signal undergoing the synchronous detection processing is subjected to weighting corresponding to the receiving level in each subcarrier, subsequently, subjected to soft decision to a transmission time signal point by a soft decision circuit 107, converted into bit data and outputted. The received signal converted into the bit data undergoes error correction processing with Viterbi decoding by a decoding part 108 and received data is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a receiving device,
In particular, the present invention relates to a receiving apparatus and a receiving method in multicarrier wireless communication using quadrature amplitude modulation.

[0002]

2. Description of the Related Art In digital mobile communication, when a transmitting station modulates a signal by a modulation method in which information is superimposed only on a phase, a receiving station needs to correct the phase rotation of a received signal.

A typical modulation method in which information is superimposed only on the phase is QPSK (Quadrature).
Phase Shift Keying).

[0004] Further, when modulation is performed by a transmitting station by a modulation method in which information is superimposed on phase and amplitude, the receiving station needs to correct not only the phase but also the amplitude of the received signal.

A typical modulation method in which information is superimposed on phase and amplitude is quadrature amplitude modulation (Quadra).
cure Amplitude Modulatio
n; hereinafter, referred to as QAM). In QAM,
There are 16-value QAM, 64-value QAM, 256-value QAM, and the like.

In a modulation method such as QPSK in which information is superimposed only on a phase, as the number of values increases, the interval between signal points on the IQ plane becomes narrower, and the error rate characteristics deteriorate. Therefore, it is considered that QAM in which information is superimposed not only on the phase but also on the amplitude will be used more often in the future where the multi-value is expected to be advanced.

[0007] Hereinafter, a conventional receiving apparatus which corrects not only the phase but also the amplitude corresponding to the communication using QAM will be described with reference to FIGS. 5 to 7. FIG. 5 is a main block diagram showing a schematic configuration of a conventional receiving apparatus.
Is a main block diagram showing a schematic configuration of a conventional synchronous detection circuit of a receiving apparatus, and FIG. 7 is a main block diagram showing a schematic configuration of a soft decision circuit of the conventional receiving apparatus.

[0008] The conventional receiving apparatus described below is
The case where it is used for multicarrier wireless communication using 16-value QAM is shown. However, for the sake of simplicity, signals of a plurality of streams are also indicated by a single arrow in the figure. Also, it is assumed that a known symbol for acquiring symbol synchronization timing is inserted into the radio signal by the transmitting station.

In FIG. 5, an antenna 501 receives a radio signal, a receiving section 502 performs a receiving process on the received signal, and a timing control section 503 responds to the symbol synchronization timing acquired by the receiving section 502. Fast Fourier Transform (Fast Fourier Transform)
r Transform (hereinafter referred to as FFT) unit 50
4 performs FFT processing on the input signal.

[0010] Various methods have already been proposed for obtaining symbol synchronization timing in receiving section 502, and a detailed description thereof will be omitted here.

[0011] The synchronous detection circuit 505 performs synchronous detection processing on the received signal, and removes the influence of phase rotation and amplitude fluctuation on the received signal due to fading or the like. Soft decision section 506 performs a soft decision on the received signal after the synchronous detection processing, converts the received symbol into bit data, and outputs the bit data.

[0012] Decoding section 507 performs error correction processing on the bit data of the received signal obtained by the soft decision to obtain received data. The error correction processing here uses Viterbi decoding.

In FIG. 6, which shows a schematic configuration of the synchronous detection circuit 505, a known symbol extraction section 601 extracts a signal in a known symbol section from a received signal based on a symbol synchronization timing specified by a timing control section 503. The signal is output to the multiplier 602, and the signal in the data symbol section is output to the arithmetic unit 607.

Here, the signal In (nT) in the known symbol section in the received signal is expressed as: In (nT) = P (nT) · A (nT) · exp (jΘ)
(NT)). Here, P (nT) is a known symbol, A (nT) is amplitude fluctuation due to fading or the like, and exp (jΘ (nT)) is a phase rotation amount due to fading or the like.

The multiplier 602 multiplies a signal in a known symbol section of the received signal by a known symbol held in advance, and calculates a phase rotation and an amplitude variation of the received signal due to the influence of fading or the like.

Here, the output of the multiplier 602 is represented by F (nT)
F (nT) = In (nT) · P (nT) = P (nT) ² · A (nT) · exp (jΘ (nT)) − where P (nT ) ² = 1, so the equation can be expressed as: F (nT) = A (nT) .exp (jΘ (nT)).

As described above, the output of the multiplier 602 is A
Since it is expressed only by (nT) and exp (jΘ (nT)), a signal representing the phase rotation and amplitude fluctuation of the received signal due to the influence of fading or the like is obtained.

The sum of squares calculation unit 603 calculates the sum of squares of the I component and the Q component of the output of the known symbol extraction unit 601.
The square value A ² (nT) of the amplitude variation of the received signal is obtained.

The divider 604 outputs the output of the multiplier 602 to A
Divide by ² (nT). Output F (nT) ′ of divider 604
F (nT) ′ = F (nT) / A ² (nT) = {A (nT) · exp (jΘ (nT))} / A ² (nT) = exp (jΘ (nT)) / A ( nT). The memory 605 includes a divider 604
Output F (nT) ′ is temporarily stored.

The switch 606 is connected to the timing control unit 50
3 based on the symbol synchronization timing indicated by
While the signal in the data symbol section of the received signal is input to the operation unit 607, the divider 604 stored in the memory 605
Is output to the arithmetic unit 607.

The operation unit 607 generates a conjugate complex number of the output of the division unit 604, and multiplies the conjugate complex number by the signal in the data symbol section of the received signal. The conjugate complex number F (nT) ^* of the output F (nT) ′ of the division unit 604 can be expressed as F (nT) ^* = exp (−jΘ (nT)) / A (nT).

Assuming that the transmitted data symbol is D (nT), the signal D _in (n) _in the data symbol section of the received signal
T) is D _in (nT) = D (nT) · A (nT) · exp (jΘ
(NT)), the output D _{out of the} arithmetic unit 607
(NT) is: D _out (nT) = D _in (nT) · F (nT) ^* = D (nT) · A (nT) · exp (jΘ (nT)) · ｛exp (−jΘ (nT)) / A (nT)｝ = D (nT) −.

In the above equation, terms indicating phase rotation and amplitude fluctuation due to the effects of fading and the like have disappeared.
Only the phase information and the amplitude information of the data symbol D (nT) are obtained.

Here, in radio communication using the 16-level QAM system, the data symbol transmitted from the transmitting station takes any one of 16 signal points on the IQ plane. Removing the phase rotation and the amplitude fluctuation from will result in any of the 16 signal points on the IQ plane. As described above, the signal point at the time of transmission of the received symbol is determined by the synchronous detection processing.

As described above, the synchronous detection circuit 505 can correct the phase and amplitude of the received signal and return the received symbol to the signal point at the time of transmission on the IQ plane.

In FIG. 7 showing a schematic configuration of the soft decision circuit 506, a threshold value A is a reference value for returning a signal point to (0, 0), and a threshold value B is a synchronous detection signal. I
The threshold value C is a threshold value for determining whether the component and the Q component are larger or smaller than the transmission signal point on the IQ plane. This is a threshold for determining whether or not there is.

The synchronous detection signal input to soft decision circuit 506 is decomposed by switch 701 into an I component and a Q component.

The I component is compared with a threshold value B by a quantization unit 706, and it is determined whether the I component is larger or smaller than a signal point at the time of transmission on an IQ plane, and bit data is output. Here, assuming that the resolution of the quantization units 706 to 709 is 6 bits, the output signal of the quantization unit 706 is bit data consisting of 6 bits obtained by determining the magnitude of the I component of the received symbol.

For the I component, the absolute value of the amplitude is calculated by the absolute value calculation unit 702, the threshold value A is subtracted by the subtractor 704, and the I component of the signal point at the time of transmission is set to 0. Further, the quantization unit 707 compares the threshold value C with the threshold value C to determine the distance in the I component direction from the transmission signal point to the reception symbol.

As described above, the output signal of quantization section 707 is bit data composed of 6 bits obtained by determining the amplitude value in the I component direction from the transmission signal point of the received symbol.

Further, the Q component is processed in the same manner, and the output signal of the quantization unit 708 is bit data composed of 6 bits obtained by judging the magnitude of the Q component of the received symbol. The signal is bit data composed of 6 bits obtained by determining the amplitude of the Q component of the received symbol.

As described above, the soft decision circuit 506 restores the bit data mapped at the transmitting station by determining the distance on the IQ plane from the received symbol to the signal point at the time of transmission.

As described above, the conventional receiving apparatus can correct the phase and the amplitude of the received signal by the synchronous detection circuit 505. Therefore, the signal received by the 16QAM system is received, demodulated, and received. Data can be obtained.

[0034]

However, in the conventional receiving apparatus, when receiving a signal modulated by the 16QAM system in multicarrier radio communication, the effect of Viterbi decoding is reduced and the error rate characteristic is deteriorated. There is a problem. Details will be described below.

In the error correction processing in Viterbi decoding, a path having the lowest likelihood sum of all subcarriers is selected.

The likelihood of each subcarrier is a distance on the IQ plane between a reception point of each symbol of each subcarrier and a signal point to be originally received detected by the synchronous detection circuit. It is obtained by the soft decision circuit 506.

However, as described above, in the conventional receiving apparatus, in order to receive the radio signal modulated by the 16-level QAM system and to detect the transmission signal point in the synchronous detection processing, not only the phase but also the amplitude is required. Need to be corrected.

Correcting the amplitude of the received signal means that the amplitude of the subcarrier whose reception level is falling can be raised to the level of other carriers. When the amplitude values are thus aligned, the quantization units 706 to 706
The distance between the received symbol and the signal point at the time of transmission calculated by 709, that is, the likelihood is equal in the subcarrier.

Therefore, for example, when there is a carrier whose reception level is falling, when the likelihood is calculated in the quantization units 706 to 709, the likelihood that if the amplitude correction is not performed, it is supposed to increase due to the reception level falling. The likelihood whose degree is lower than the actual one is calculated.

The low likelihood means that the reception level is good. Therefore, the fact that the reception level is good despite the fact that the reception level is bad is transmitted to the decoding unit 507.

As described above, in the conventional receiving apparatus that performs amplitude correction in QAM wireless communication, the soft decision circuit calculates the likelihood that does not accurately reflect the actual reception state, and calculates the likelihood based on the likelihood. As a result, the problem that the error rate characteristic deteriorates occurs.

The present invention has been made in view of the above point, and in a multicarrier radio communication using a modulation method in which information is superimposed on a phase and an amplitude, the phase of a received signal is not deteriorated without deteriorating the error rate characteristic. And a receiver for correcting the amplitude.

[0043]

The gist of the present invention is that in a multicarrier radio communication using a modulation method in which information is superimposed on a phase and an amplitude, a receiving apparatus corrects the phase and the amplitude by a synchronous detection process. , After detecting a signal point at the time of transmission on the IQ plane, weighting the received symbol by multiplying it by the amplitude value of each subcarrier, and then calculating the likelihood reflecting the actual reception state by soft decision, Viterbi decoding is performed on these likelihoods.

[0044]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A receiving apparatus according to a first aspect of the present invention includes a receiving means for receiving a signal transmitted by superimposing information on a phase and an amplitude, and correcting phase rotation and amplitude fluctuation of a received symbol. Synchronous detecting means, a quantizing means for converting received symbols corrected by the synchronous detecting means into bit data by soft decision processing, and a stage before the corrected received symbols are converted to bit data by the quantizing means. And weighting means for multiplying the corrected received symbol by an amplitude value of the received symbol at the time of reception.

According to this configuration, when receiving a signal transmitted by multicarrier radio using a modulation method in which information is superimposed on the phase and the amplitude, the reception after the phase and the amplitude are corrected by the synchronous detection processing By performing weighting according to the amplitude value of each subcarrier before performing the soft decision processing on the signal, the actual reception state can be reflected in the Viterbi decoding processing, so that the error rate characteristics deteriorate. Can be prevented.

In the receiving apparatus according to a second aspect of the present invention, in the first aspect, the weighting means averages an amplitude value at the time of reception of a received symbol to calculate a time average value for each carrier. And a normalizing unit that normalizes the amplitude value at the time of reception of the received symbol by using the time average value of the carrier to which the received symbol is sent.

According to this configuration, before multiplying the amplitude value of each subcarrier by the received signal after the synchronous detection processing, the amplitude value of each subcarrier is normalized by the time average value, and the relative value of the amplitude value of each subcarrier is multiplied. Therefore, even when the reception levels of all subcarriers are entirely reduced, it is possible to prevent the resolution at the time of quantization from lowering and obtain correct bit data.

[0048] In a receiving apparatus according to a third aspect of the present invention, in the second aspect, the quantizing means may be different from a judging section for judging the output of the averaging section to an arbitrary threshold value. If the two thresholds and the output of the averaging unit are smaller than the threshold, the smaller of the two thresholds is selected, and the output of the averaging unit is the threshold. When the value is larger than the value, a selection unit that selects the larger value of the two threshold values is adopted.

According to this configuration, when the reception levels of all subcarriers are entirely lowered, the threshold value used for quantization is changed to a small value, so that the resolution at the time of quantization is maintained and correct bit data Can be obtained. In addition, since the resolution at the time of quantization omitted without using a divider can be prevented from being lowered, and correct bit data can be obtained,
The hardware scale can be simplified.

A communication terminal device according to a fourth aspect of the present invention employs a configuration including the receiving device according to any one of the first to third aspects.

According to this configuration, in multicarrier radio communication using a modulation method in which information is superimposed on phase and amplitude, it is possible to correct the phase and amplitude of a received signal without deteriorating the error rate characteristics. it can.

[0052] The base station apparatus according to the fifth aspect of the present invention comprises:
A configuration including the receiving device according to any one of the first to third aspects is adopted.

According to this configuration, in multicarrier radio communication using a modulation method in which information is superimposed on phase and amplitude, it is possible to correct the phase and amplitude of a received signal without deteriorating the error rate characteristics. it can.

A receiving method according to a sixth aspect of the present invention includes a receiving step of receiving a signal transmitted with information superimposed on a phase and an amplitude, and a synchronous detecting step of correcting phase rotation and amplitude fluctuation of a received symbol. And a quantization step of converting the received symbol corrected by the synchronous detection step into bit data by soft decision processing, and a step before the corrected received symbol is converted into bit data by the quantization step. And a weighting step of multiplying a subsequent received symbol by an amplitude value of the received symbol at the time of reception.

According to this method, when receiving a signal transmitted by multicarrier radio using a modulation method in which information is superimposed on the phase and the amplitude, the reception after the phase and the amplitude are corrected by the synchronous detection processing By performing weighting according to the amplitude value of each subcarrier before performing the soft decision processing on the signal, the actual reception state can be reflected in the Viterbi decoding processing, so that the error rate characteristics deteriorate. Can be prevented.

In a receiving method according to a seventh aspect of the present invention, in the sixth aspect, the weighting step includes averaging an amplitude value at the time of reception of the received symbol to calculate a time average value for each carrier. And a normalizing step of normalizing the amplitude value at the time of reception of the received symbol using the time average value of the carrier to which the received symbol is sent.

According to this method, before multiplying the amplitude value of each subcarrier by the received signal after the synchronous detection processing, the amplitude value of each subcarrier is normalized by the time average value, and the relative value of the amplitude value of each subcarrier is obtained. Therefore, even when the reception levels of all subcarriers are entirely reduced, it is possible to prevent the resolution at the time of quantization from lowering and obtain correct bit data.

[0058] In a receiving method according to an eighth aspect of the present invention, in the seventh aspect, in the quantizing step, the output of the averaging step is determined to be larger or smaller than an arbitrary threshold value. When the output is smaller than the threshold, the magnitude of the threshold is reduced, and when the output of the averaging step is larger than the threshold, the magnitude of the threshold is increased.

According to this method, when the reception levels of all the subcarriers are entirely lowered, the threshold value used for quantization is changed to a small value. Can be obtained. In addition, since the resolution at the time of quantization omitted without using a divider can be prevented from being lowered, and correct bit data can be obtained,
The hardware scale can be simplified.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

In each of the following embodiments, a case is shown in which the receiving apparatus of the present invention is used for multicarrier radio communication using 16-level QAM. However,
For the sake of simplicity, signals of a plurality of streams are also indicated by a single arrow in the figure. Also, it is assumed that a known symbol for acquiring symbol synchronization timing is inserted into the radio signal by the transmitting station.

(Embodiment 1) The receiving apparatus according to the present embodiment performs weighting on a received signal after synchronous detection according to amplitude fluctuation.

Hereinafter, the receiving apparatus according to the present embodiment will be described using FIG. 1 and FIG. FIG. 1 is a main block diagram showing a schematic configuration of a receiving apparatus according to Embodiment 1 of the present invention, and FIG. 2 is a schematic configuration of a soft decision circuit of the receiving apparatus according to Embodiment 1 of the present invention. It is a principal part block diagram shown.

In FIG. 1, antenna 101 receives a radio signal, receiving section 102 performs a receiving process on the received signal, and timing control section 103 controls the signal in accordance with the symbol synchronization timing acquired in receiving section 102. The FFT unit 104 controls an FFT on the input signal.
Perform processing.

Various methods have already been proposed for obtaining the symbol synchronization timing in the receiving section 102, and any method may be used here.

The synchronous detection circuit 105 performs a synchronous detection process on the received signal, and removes the influence of the phase rotation and the amplitude fluctuation on the received signal due to fading or the like. In addition,
Regarding the correction of the phase and the amplitude here, since the same configuration and method as those of the above-described conventional receiving apparatus are employed, detailed description thereof will be omitted.

The level calculator 106 calculates the reception level of each subcarrier from the received signal after the FFT processing.

The soft decision circuit 107 performs soft decision after weighting the received signal after the synchronous detection processing according to the reception level, and outputs bit data. Details will be described later.

Decoding section 108 performs error correction processing on the bit data of the received signal obtained by the soft decision to obtain received data. The error correction processing here uses Viterbi decoding.

Next, the operation of the receiving apparatus having the above configuration will be described.

First, the reception signal received by the antenna 101 and the reception unit 102 is subjected to reception processing by the reception unit 102, and the symbol synchronization timing is detected.
The detected symbol synchronization timing is sent to the FFT unit 104 and the synchronous detection circuit 1 by the timing control unit 103.
05 is indicated.

Next, FFT processing is performed on each subcarrier by FFT section 104. The received signal after the FFT processing is subjected to synchronous detection processing by the synchronous detection circuit 105, and the effects of phase rotation and amplitude fluctuations caused by fading or the like are removed. Also, the level calculator 106
The reception level of the reception signal after the T processing is calculated.

The received signal subjected to the synchronous detection processing is weighted according to the reception level for each subcarrier by the soft decision circuit 107, and then soft-decision is performed on the signal point at the time of transmission, and is converted into bit data. Output.

The received signal converted into bit data is
An error correction process by Viterbi decoding is performed by the decoding unit 108, and received data is obtained.

Next, the configuration and operation of the soft decision circuit according to the present embodiment will be described with reference to FIG.

In FIG. 2, threshold value A is a reference value for returning the signal point to (0, 0), and threshold value B is
The threshold C is a threshold for determining whether the I component and the Q component of the synchronous detection signal are larger or smaller than the transmission signal point on the IQ plane. The threshold C is the magnitude of the amplitude value, that is, the transmission signal point. This is a threshold value for determining how much interval there is.

The switch 201 decomposes the input synchronous detection signal into an I component and a Q component. Absolute value calculation sections 206 and 207 calculate the absolute value of each of the I and Q components of the synchronous detection signal, and subtracters 208 and 209 subtract the threshold value A from each of the I and Q components of the synchronous detection signal. Then, the I component and the Q component of the signal point during transmission are set to 0.

Each of the multipliers 202 to 205 multiplies each signal before quantization by a reception level output from the level calculator 106, and performs weighting based on the amplitude value of each subcarrier.

Here, since the signals input to the multipliers 202 to 205 have been subjected to amplitude correction by the synchronous detection circuit 105, regardless of the magnitude of the reception level of each subcarrier, The signal derived from the carrier has the same amplitude value.

Therefore, by multiplying the reception level of each subcarrier by the multipliers 202 to 205 to make the amplitude value of each signal proportional to the level of the reception level of each subcarrier, the actual reception level is increased. Weighting reflecting the state can be performed.

Quantization section 210 compares the output of multiplier 202 with threshold value B, determines whether the I component is larger or smaller than the signal point at the time of transmission on the IQ plane, and outputs bit data. I do. Here, assuming that the resolution of the quantization units 210 to 213 is 6 bits, the output signal of the quantization unit 210 is bit data composed of 6 bits obtained by determining the magnitude of the I component of the received symbol.

The quantizing section 211 compares the output of the multiplier 203 with the threshold value C, determines the distance in the I component direction from the signal point at the time of transmission to the received symbol, and outputs bit data consisting of 6 bits. I do.

The quantization unit 212 performs the same processing as that of the quantization unit 210 on the Q component, and the quantization unit 213 performs the same processing as that of the quantization unit 211 on the Q component.

As described above, the soft decision circuit 107 determines the distance on the IQ plane from the received symbol weighted according to the amplitude value of each subcarrier to the signal point at the time of transmission, so that the Restore the mapped bit data.

These bit data are Viterbi-decoded by the decoding unit 108 and subjected to error correction processing. Here, the Viterbi decoding selects the path with the lowest likelihood, that is, the path with the shortest distance on the IQ plane from the received symbol to the signal point at the time of transmission. By performing weighting according to the value, the decoding unit 108 can perform Viterbi decoding based on the actual reception state.

As described above, according to the present embodiment, QA
When receiving a signal transmitted by multi-carrier wireless transmission using the M method, before performing a soft decision process on the received signal after the phase and amplitude are corrected by the synchronous detection process,
By performing weighting according to the amplitude value of each subcarrier, it is possible to reflect the actual reception state in the Viterbi decoding process, so that it is possible to prevent the error rate characteristics from deteriorating.

(Embodiment 2) The receiving apparatus according to the present embodiment has the same configuration as that of Embodiment 1, except that the amplitude value of each subcarrier multiplied by the signal after the synchronous detection processing is set This is to normalize in advance with the time average of the carrier amplitude value.

Hereinafter, the receiving apparatus according to the present embodiment will be described with reference to FIG. FIG. 3 is a main block diagram showing a schematic configuration of the soft decision circuit of the receiving apparatus according to Embodiment 2 of the present invention. The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description is omitted.

In the first embodiment, for example, when the AGC does not operate properly or the like, if the reception levels of all the sub-carriers are totally reduced and the weights by the multipliers 202 to 205 are reduced as a whole, Quantization unit 2
The resolution in 10 to 213 decreases, and correct bit data cannot be obtained.

Therefore, in this embodiment, the multiplier 202
Regarding the weighting in steps 205 to 205, if the ratio of each relative subcarrier can be multiplied without directly multiplying the amplitude value at the time of reception of the received symbol, the weighting effect of the present invention can be obtained. A value obtained by dividing the amplitude value of the carrier by the time average of the amplitude values of the subcarriers is used for weighting.

In FIG. 3, an averaging device 301 calculates a time average of the amplitude values of each subcarrier. The averaging time may be arbitrary. The divider 302 divides the amplitude value of each subcarrier by the time average of the amplitude value of each subcarrier output from the averaging device 301, normalizes the amplitude value of each subcarrier, and The relative ratio of the amplitude value is input to multipliers 202-205.

As described above, according to the present embodiment, before multiplying the amplitude value of each subcarrier by the received signal after the synchronous detection processing, the amplitude value of each subcarrier is normalized by the time average value of each subcarrier and each subcarrier is normalized. Since weighting is performed based on the relative ratio of carrier amplitude values, it is possible to prevent the resolution during quantization from lowering and to obtain correct bit data even when the reception levels of all subcarriers are entirely reduced. it can.

(Embodiment 3) The receiving apparatus according to the present embodiment has the same configuration as that of Embodiment 1, except that the threshold value used for quantization depends on the magnitude of the average amplitude value of each subcarrier. Is to change.

Hereinafter, the receiving apparatus according to the present embodiment will be described with reference to FIG. FIG. 4 is a main block diagram showing a schematic configuration of the soft decision circuit of the receiving apparatus according to Embodiment 3 of the present invention. The same components as those of the second embodiment are denoted by the same reference numerals, and the detailed description is omitted.

In the present embodiment, when the reception levels of all subcarriers are entirely reduced, the threshold used for quantization is changed to a small value, so that the resolution in quantization sections 210 to 213 is maintained. And obtain correct bit data.

In this embodiment, the threshold value D
Is an arbitrary threshold value used for determining the magnitude of the average amplitude value. The threshold values B1 and B2 are the same as those in the first and second embodiments.
, Which has the same role as the threshold value B in this example, and here, threshold value B1> threshold value B2. Similarly, thresholds C1 and C2 are thresholds having the same role as threshold C in the first and second embodiments.
Here, it is assumed that threshold value C1> threshold value C2.

In FIG. 4, a subtractor 401 subtracts an average amplitude value of each subcarrier, which is an output of the averaging device 301, from a threshold value D, and a decision device 402 judges the magnitude.

The result of the determination by the determiner 402 controls the switching of the switches 403 and 404. When the average amplitude value of each subcarrier is larger than an arbitrary threshold value D, the threshold value B1 and the threshold value C1 are used. When the average amplitude value of each subcarrier is smaller than an arbitrary threshold value D, threshold value B2 and threshold value C2 are used.

As described above, according to the present embodiment, when the reception levels of all the subcarriers are totally reduced,
Since the threshold value used for quantization is changed to a small value, the resolution at the time of quantization can be maintained and correct bit data can be obtained.

In addition, since the resolution at the time of quantization can be prevented from lowering by the configuration without using the divider and correct bit data can be obtained, the hardware scale can be simplified as compared with the second embodiment. it can.

In the first to third embodiments,
Although the case where the receiving apparatus of the present invention is applied to multi-carrier wireless communication using 16-level QAM has been described, the receiving apparatus of the present invention is not limited to this case, and the division is superimposed on the phase and amplitude. Any modulation scheme other than 16-level QAM can be applied, as well as single-carrier wireless communication. However, in consideration of the effect of fading, it is preferable to use it for multicarrier wireless communication.

[0102]

As described above, according to the present invention,
In multicarrier wireless communication using a modulation method in which information is superimposed on phase and amplitude, it is possible to correct the phase and amplitude of a received signal without deteriorating error rate characteristics.

[Brief description of the drawings]

FIG. 1 is a main block diagram showing a schematic configuration of a receiving apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a main block diagram showing a schematic configuration of a soft decision circuit of the receiving apparatus according to Embodiment 1 of the present invention.

FIG. 3 is a main block diagram showing a schematic configuration of a soft decision circuit of a receiving apparatus according to Embodiment 2 of the present invention.

FIG. 4 is a main block diagram showing a schematic configuration of a soft decision circuit of a receiving apparatus according to Embodiment 3 of the present invention.

FIG. 5 is a main block diagram showing a schematic configuration of a conventional receiving apparatus.

FIG. 6 is a main block diagram showing a schematic configuration of a synchronous detection circuit of a conventional receiver.

FIG. 7 is a main block diagram showing a schematic configuration of a soft decision circuit of a conventional receiver.

[Explanation of symbols]

 105 Synchronous detection circuit 106 Level calculator 107 Soft decision circuit 202-205 Multiplier 301 Averager

Claims (8)

[Claims] 1. A receiving means for receiving a signal transmitted with information superimposed on a phase and an amplitude, a synchronous detecting means for correcting a phase rotation and an amplitude fluctuation of a received symbol, and a reception corrected by the synchronous detecting means. A quantizing means for converting a symbol into bit data by soft decision processing; and a stage before receiving the corrected received symbol, And a weighting means for multiplying the amplitude value by: 2. The weighting means, comprising: an averaging unit that averages amplitude values of received symbols at the time of reception to calculate a time average value for each carrier; The receiving apparatus according to claim 1, further comprising: a normalizing unit that normalizes the transmitted carrier using the time average value. 3. The quantizing means includes: a judging section for judging the output of the averaging section to be larger or smaller than an arbitrary threshold; two thresholds having different magnitudes; When the output is smaller than the threshold, the smaller value of the two thresholds is selected. When the output of the averaging unit is larger than the threshold, the larger value of the two thresholds is selected. 3. The receiving device according to claim 2, further comprising: a selection unit that selects 4. A communication terminal device comprising the receiving device according to claim 1. 5. A base station device comprising the receiving device according to claim 1. Description: 6. A receiving step of receiving a signal transmitted with information superimposed on a phase and an amplitude, a synchronous detecting step of correcting a phase rotation and an amplitude fluctuation of a received symbol, and a receiving corrected by the synchronous detecting step. A quantization step of converting a symbol into bit data by a soft decision process, and a stage before the corrected reception symbol is converted into bit data by the quantization step, in which the reception symbol after the correction is received. And a weighting step of multiplying the amplitude value by: 7. The averaging step of averaging the amplitude value of a received symbol at the time of reception to calculate a time average value for each carrier, and the weighting step comprises:
7. The receiving method according to claim 6, further comprising: a normalizing step of normalizing using the time average value of the carrier to which the received symbol is sent. 8. The quantization step judges the magnitude of the output of the averaging step as an arbitrary threshold, and determines the magnitude of the threshold when the output of the averaging step is smaller than the threshold. 8. The receiving method according to claim 7, wherein the threshold value is reduced, and the magnitude of the threshold value is increased when the output of the averaging step is larger than the threshold value.