JP2000232393A - Phase correction device for CDMA reception signal - Google Patents

Abstract

(57) Abstract: A phase correction device that accurately corrects phase rotation of a received signal using an in-phase signal and a quadrature signal detected from a signal received by a CDMA method using an output signal of an oscillator. And a CDMA receiver. SOLUTION: A partial correlation value acquiring means 5 of a CDMA receiver is provided.
For example, for each of the in-phase signal and the quadrature signal for one spreading code, for example, a partial correlation value of the first half signal part and a partial correlation value of the second half signal part are obtained,
In 8, 2 relating to the first half signal portion obtained at the time of the correlation peak
The phase rotation between the vector composed of the two partial correlation values and the vector composed of the two partial correlation values relating to the latter half of the signal portion is detected, and the correcting means 10 performs the phase rotation of the received signal based on the average value of the phase rotation. Is corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CDMA receiving signal phase correction apparatus and a CDMA receiver for correcting the phase rotation of a signal received by the CDMA method, and more particularly, to a CDMA receiver having a relatively large phase rotation. The present invention relates to a technique for correctly correcting phase rotation.

[0002]

2. Description of the Related Art For example, DS-CDMA (Direct Sequenc)
In a mobile communication system using the e Code Division Multiple Access (direct spreading code division multiple access) method, multiplexing communication is performed by assigning an individual spreading code to each channel for communication. In such a mobile communication system, for example, a CDMA transmitter inserts pilot symbols into transmission symbols and transmits these symbols wirelessly, while a CDMA receiver receives the symbols and receives the pilot symbols. The amplitude / phase variation is detected from the despread signal, and the amplitude and phase of the received symbol are corrected using the detected amplitude / phase variation.

FIG. 4 shows an example of a communication frame transmitted from the CDMA transmitter as described above. In this communication frame configuration, pilot symbols are periodically inserted into data symbols to be transmitted. ing. In addition,
The pilot symbol pattern is the same as the CDMA transmitter and C
The same pattern is set in the DMA receiver.

FIG. 5 shows a configuration example of a CDMA receiver. The CDMA receiver includes an oscillator 41 for outputting a signal (carrier) and a quadrature detector 42 for performing quadrature detection.
A spreading code generating unit 43 for generating a spreading code used in the transmission channel, a matched filter (MF) 44 for performing despreading, a path timing detecting unit 45 for detecting path timing, Path extractor 46 for outputting a spread symbol (a received symbol after despreading)
And a demodulation unit F for demodulating, decoding, and determining data from the despread symbols.

The demodulation unit F includes a plurality of synchronous detection units D1 to Dm for performing synchronous detection and a plurality of synchronous detection units D1 to Dm.
A combining unit 52 that combines the despread symbols after amplitude / phase compensation output from m and a determination unit 53 that determines the despread symbols after combining are provided. Here, a plurality of synchronous detection units D1 to Dm are provided corresponding to a plurality of paths.

Each of the synchronous detectors D1 to Dm has a reference pilot symbol generator 47 for generating a reference pilot symbol and a complex conjugate multiplication result of the despread symbol and the reference pilot symbol. A complex conjugate multiplier 48 for outputting as a fluctuation amount, an averaging unit 49 for outputting the amplitude / phase fluctuation amount averaged over a plurality of symbols as an amplitude / phase compensation value, and a delay unit 50 for delaying a despread symbol. And a complex conjugate multiplier 51 that performs complex conjugate multiplication of the delayed despread symbol and the amplitude / phase compensation value to compensate for the despread symbol. In addition, since the configuration of each of the synchronous detection units D1 to Dm is the same, FIG. 5 shows only the configuration of the first synchronous detection unit D1, and the configuration of the second synchronous detection unit D2 to the m-th synchronous detection unit Dm Illustration is omitted.

Next, an example of the processing performed by the CDMA receiver having the above configuration will be described, and the phase rotation occurring in the received signal will be described. That is, CDMA
Radio frequency band signal (RF signal)
Is input to the quadrature detection unit 42, and the carrier output from the oscillator 41 is input to the quadrature detection unit 42, and the quadrature detection unit 42 uses the carrier to quadrature the received signal with a baseband in-phase signal. The signals are converted (down-converted) into signals (that is, decomposed into baseband in-phase and quadrature components), and the converted in-phase and quadrature signals are output to the matched filter 44.

The above-mentioned in-phase signal and quadrature signal are input to the matched filter 44, and the in-phase and quadrature spreading codes generated by the code generator 43 are input as reference spreading codes. In 44,
By despreading the in-phase signal by correlating the input in-phase signal with the spread code corresponding to the in-phase signal, the input quadrature signal is correlated with the spread code corresponding to the quadrature signal. This despreads the orthogonal signal.

The signal despread by the matched filter 44 is output to a path timing detector 45 and a path extractor 46. The path timing detector 45 detects the timing at which a correlation peak appears from the input despread signal. Then, the detected timing is output to the path extracting unit 46 as the path timing. The path extracting section 46 outputs the despread signal at the path timing input from the path timing detecting section 45 among the despread signals output from the matched filter 44 to the demodulating section F as a despread symbol.

Here, the despread symbols output from the path extraction unit 46 to the demodulation unit F include, for example, a phase error due to fading and a frequency error due to the accuracy of the oscillator 41 (error in the oscillation frequency of the oscillator). Since such errors are included, phase rotation (phase shift) occurs in the in-phase signal and the quadrature signal in the despread symbol. In addition, for example, amplitude fluctuation occurs in the despread symbol.

Here, for convenience of explanation, the above-described phase rotation will be described more specifically on the assumption that amplitude fluctuation does not occur in the above-mentioned despread symbol. For example, the coordinate point of the despread symbol when no phase rotation occurs is A (I, Q), and the coordinate point of the despread symbol when the phase rotation of phase Φ occurs is A ′ (I ′, Q). ')
Then, I ′ and Q ′ are expressed as in Equation 1. In addition,
I and I corresponding to the X coordinate of the coordinate point represent the in-phase component (component of the in-phase signal) of the despread symbol, and Q and Q ′ corresponding to the Y coordinate of the coordinate point represent the orthogonal component ( (A component of a quadrature signal).

[0012]

(Equation 1)

As shown in the above equation (1), a despread symbol composed of an in-phase signal and a quadrature signal that are orthogonal to each other is expressed in quadrature coordinates (XY coordinates) when there is no phase rotation. Is rotated by the phase rotation Φ. In FIG. 6, an example of the above-described one coordinate point A is indicated by a black circle and an example of the other coordinate point A ′ is indicated by a white circle. It rotates by the phase rotation Φ with respect to the point A.

As described above, in the despread symbol output from the path extraction unit 46, a phase rotation occurs in the in-phase component and the quadrature component, and the despread symbol in which such phase rotation has occurred is detected by the synchronous detection of the demodulation unit F. The data is input to the units D1 to Dm.
Then, in the synchronous detection units D1 to Dm, as follows:
The phase rotation of the despread symbol is extracted and compensated (corrected) using the pilot symbol for reference.

For example, received symbols (despread symbols)
Is a pilot symbol, it is assumed that the pilot symbol that should be at the above-mentioned coordinate point A is input to the synchronous detectors D1 to Dm as a symbol of the coordinate point A ′ by the phase rotation Φ. The reference pilot symbol generators 47 of the synchronous detectors D1 to Dm output the symbol corresponding to the coordinate point A as a reference pilot symbol, and input the reference pilot symbol (coordinate point A) and the path extractor 46. Pilot symbol (coordinate point A ')
Are subjected to complex conjugate multiplication by the complex conjugate multiplier 48.

In the complex conjugate multiplication by the complex conjugate multiplier 48, the phase variation B (cosΦ, sinΦ) of the symbol at the coordinate point A ′ with respect to the symbol at the coordinate point A is calculated. It corresponds to the phase rotation Φ of A ′. FIG. 7 shows an example of the phase fluctuation amount B. The averaging unit 49 includes a complex conjugate multiplier 48
Is input, and the averaging unit 4
In step 9, the input phase variation B is averaged over a plurality of pilot symbols to reduce the effect of noise, and the average value of the phase variation is output to the complex conjugate multiplier 51 as a phase compensation amount.

On the other hand, the pilot symbol (coordinate point A ') output from the path extraction unit 46 is input to a delay unit 50, which delays the pilot symbol by the averaging time of the averaging unit 49. Output to the complex conjugate multiplier 51. The complex conjugate multiplier 51 performs complex conjugate multiplication of the delayed pilot symbol input from the delay unit 50 and the phase compensation amount input from the averaging unit 49, that is, the pilot symbol is inversely rotated by the phase Φ. The original symbol (symbol at coordinate point A) is reproduced.

For example, when the received symbol (despread symbol) is a data symbol other than the pilot symbol, the phase rotation occurring in the received symbol is considered to be constant over the period of the pilot symbol, and By using the phase compensation amount calculated using the pilot symbols as the compensation amount of the data symbol as it is, the data symbol is compensated and the original data symbol is reproduced.

In the synchronous detectors D1 to Dm, the data symbols are compensated while updating the above-mentioned phase compensation amount for each cycle of the pilot symbols, and the original data symbols are reproduced. Further, as described above, the synchronous detection units D1 to D
m are provided. Each of the synchronous detectors D1 to Dm performs synchronous detection on each path separated in the process of despreading, and the synchronous detectors D1 to Dm compensate for phase fluctuations. Are output to combining section 52.

The combining section 52 combines the data symbols for each path input from the plurality of synchronous detection sections D1 to Dm and outputs the combined data symbols to the determination section 53. The determination unit 53 obtains the determined binary data (“0” value or “1” value) by determining whether the combined data symbol is “0” value or “1” value. I do.

[0021]

However, in the phase correction performed by the CDMA receiver as described above, for example, a phase error generated in a received symbol (despread symbol) due to a large frequency error due to the accuracy of the oscillator is generated. If the phase rotation becomes too large to be considered to be constant over the pilot symbol period, there is a problem that the phase rotation cannot be correctly corrected. In addition, since the phase rotation cannot be correctly corrected as described above, there is a problem that the characteristics of demodulated data are greatly deteriorated.

Here, a case where the phase rotation becomes too large to be considered to be constant over the pilot symbol period will be described with reference to FIG. For example, as shown in FIG. 8A, it is assumed that an (original) pilot symbol having no phase rotation is fixedly set to a symbol at coordinates P (1, 1). As in the case of the coordinates A and A 'described above, the X coordinate of the coordinate point represents the in-phase component of the symbol, and the Y coordinate of the coordinate point represents the orthogonal component of the symbol.

As shown in FIG. 8B, a received symbol when the above-mentioned pilot symbol P is received with a certain frequency error is set as a symbol of a coordinate point L, and a phase rotation generated in the received symbol is determined. Δθ1 (for example, 0 <
Δθ1 <+ π / 2). In this case, as shown in FIG. 8C, the amount of phase variation of the received symbol is L ′ (a1, a
A1 = cos (Δθ1), and a2 =
sin (Δθ1).

As shown in FIG. 8D, a received symbol when the above-mentioned pilot symbol P is received with another frequency error is used as a symbol of a coordinate point T, and a phase rotation generated in the received symbol is determined. Δθ2 (for example, +3
π / 2 <Δθ2 <+ 2π). In this case, FIG.
As shown in (e), the phase variation of the received symbol is T ′
It is represented by (b1, b2), where b1 = cos (Δθ2) and b2 = sin (Δθ2).

Here, as shown in FIG.
For example, when the value of the phase rotation Δθ1 is a value of 0 to + π or a value of 0 to −π, the phase rotation can be correctly corrected by the phase correction shown in the above-described conventional example. However, as shown in FIG. 8D, for example, the phase rotation Δ
If the value of θ2 exceeds + π or -π, the phase rotation cannot be corrected correctly. Specifically, in the case of FIG. 8D, the actual phase rotation Δθ2
Is between + 3π / 2 and + 2π,
Δθ3 (| Δθ3 | = 2π
The phase rotation of -Δθ2) is detected as having occurred, so that the phase rotation cannot be corrected correctly.

As described above, in the phase correction as shown in the conventional example, the error detection range of the phase (the error range in which the detection can be compensated) is ± π, that is, the value of the phase rotation is ± π. If the value is within the range, the phase rotation can be corrected correctly. However, if the value of the phase rotation exceeds ± π, the actual phase variation and the detected phase variation (phase compensation amount) The error increases, and the phase rotation cannot be corrected correctly.

As described above, the case where the phase rotation becomes so large that it cannot be considered to be constant over the pilot symbol period means, for example, that the phase rotation exceeds ± π in one communication frame time. In such a case, the phase between the vector of the received symbol (for example, the vector of the coordinate T described above) and the vector of the reference pilot symbol (for example, the vector of the coordinate P described above) is obtained. Since rotation is not accurately detected, phase rotation cannot be corrected correctly.

Although a phase error due to fading also occurs in the received symbol as described above, this phase error can be generally regarded as being constant over the period of the pilot symbol, so that the above-described problem hardly occurs. . Further, in the phase correction as shown in the above conventional example, phase correction is performed using a pilot symbol in a communication frame. Therefore, it is necessary to perform phase correction using a symbol (for example, a data symbol) other than the pilot symbol. There was a problem that it could not be done.

For example, Japanese Patent Laid-Open Publication No. Hei 6-244820 discloses that an in-phase signal (Ich signal) and a quadrature signal (Qch signal) detected from a received signal by using quadrature detection are used for the in-phase signal. Automatic frequency control (AFC: Au) is performed by multiplying a spreading code (or a spreading code of an orthogonal signal) and obtaining the phase rotation (frequency deviation value) of the received signal from the multiplication result.
Although a signal processing circuit that performs phase correction by tomatically frequency control is described, in this signal processing circuit, phase rotation is performed only when the phase of one cycle of the spreading sequence (for one spreading code) can be regarded as substantially constant. Could not be corrected correctly. In other words, the phase error detection range is within ± π for one spread code (one symbol), and the phase rotation exceeding ± π in this time could not be corrected correctly.

The present invention has been made to solve such a conventional problem. For example, it is possible to correct the phase rotation of a signal received by a CDMA system using symbols other than pilot symbols. A phase correction device for a CDMA reception signal, which can substantially widen a phase error detection range, thereby correctly correcting the phase rotation even when the phase rotation of the reception signal is relatively large; It is an object to provide a CDMA receiver.

[0031]

In order to achieve the above object, a phase correction apparatus for a CDMA reception signal according to the present invention uses, for example, an in-phase signal detected from a signal received by a CDMA method using an output signal of an oscillator. And the quadrature signal, and using these signals, the phase rotation of the received signal is corrected as follows. That is, first, the partial correlation value acquiring means selects two adjacent signal portions having the same length from the detected in-phase signals for one spreading code, and corresponds to each selected signal portion and each signal portion. A partial correlation value with the spreading code is obtained, and two signal portions corresponding to each of the two signal portions are selected from the detected orthogonal signals of one spreading code, and the selected signal portions and the respective signal portions are selected. A partial correlation value between the signal part and the corresponding spreading code is obtained.

As a specific example, a case where a signal portion of (1/2) spread code ((1/2) symbol) is selected is shown. In this case, the in-phase signal of one spread code is selected. 2
Two equally divided signal parts are selected,
Two signal parts formed by dividing the orthogonal signal for one spreading code into two equal parts are selected, and partial correlation values for these four signal parts are obtained.

Next, one of the partial correlation values obtained from the in-phase signal at the time of the correlation peak by the phase rotation detecting means and the one partial correlation value corresponding to the partial correlation value obtained from the quadrature signal at the time of the correlation peak are calculated. , And a phase rotation between a vector composed of the other partial correlation value acquired from the in-phase signal and the other partial correlation value acquired from the quadrature signal.

More specifically, for example, a vector composed of components such as (one partial correlation value obtained from the in-phase signal and one partial correlation value obtained from the quadrature signal) and a vector (obtained from the in-phase signal) The phase rotation between the other partial correlation value and the vector composed of components such as the other partial correlation value acquired from the orthogonal signal) is detected. Then, the correction means corrects the phase rotation of the received signal based on the phase rotation detected as described above.

Therefore, according to the present invention, if the value of the phase rotation between the two vectors is within ± π, the phase rotation of the received signal can be correctly corrected. If the phase rotation is within ± π within the time corresponding to the signal portion (for example, 1/2 symbol or 1/4 symbol) selected from the signal, it can be corrected correctly, and the phase error detection range can be substantially reduced. Can be widened. For this reason, even when the phase rotation of the received signal is relatively large, the phase rotation can be correctly corrected, thereby preventing the characteristics of demodulated data or the like from being significantly deteriorated by the phase rotation. be able to. Further, in the present invention, for example, the phase rotation can be corrected using a symbol other than the pilot symbol.

In the CDMA reception signal phase correction apparatus according to the present invention, the phase rotation detecting means detects a plurality of phase rotations from three or more vectors, and the average value detecting means detects an average value of the plurality of phase rotations. And the correction means makes correction based on the average value detected by the average value detection means.

Therefore, for example, even if the accuracy of detecting the phase rotation is slightly deteriorated due to noise, the above-described averaging reduces the influence of the deterioration and improves the accuracy of the phase correction. Can be improved. In addition,
The above three or more vectors may be detected, for example, only in a received signal (in-phase signal and quadrature signal) for one spreading code, or may be detected, for example, in a received signal for a plurality of spreading codes. May be done.

In the CDMA received signal phase correction device according to the present invention, the correction is performed by the feedback control of the frequency of the signal output from the oscillator. As described above, by controlling and adjusting the frequency of the signal output from the oscillator, the phase of the in-phase signal or the quadrature signal detected from the received signal can be adjusted using the output signal. In addition, the phase rotation of the received signal can be corrected (for example, when there is an oscillation frequency error of the oscillator, the phase rotation due to the error can be prevented).

In the CDMA reception signal phase correction apparatus according to the present invention, the despreading means despreads the in-phase signal and the quadrature signal with corresponding spreading codes, and the correction means despreads. The phase rotation of the received signal is corrected by correcting the phase rotation of the signal. Thus, the phase rotation of the received signal can be corrected by correcting the phase rotation of the signal after despreading. Since the above-mentioned partial correlation value acquiring means and despreading means both take correlation between a received signal (in-phase signal or quadrature signal) and a spreading code, these means are shared by a common circuit or the like. It can also be configured to simplify the device.

In the CDMA receiver according to the present invention,
When a signal transmitted by the CDMA method is received and the received signal is subjected to quadrature detection using a signal output from an oscillator, the phase rotation of the received signal is corrected as follows. That is, first, the quadrature detection means detects the in-phase signal and the quadrature signal from the received signal using the signal output from the oscillator, and obtains the length from the in-phase signal for one spreading code detected by the partial correlation value acquisition means. Two adjacent signal portions having the same length are selected, and a partial correlation value between each selected signal portion and a corresponding spreading code is obtained. Two signal portions corresponding to each of the two signal portions are selected, and a partial correlation value between each of the selected signal portions and the corresponding spread code is obtained.

Next, one of the partial correlation values obtained from the in-phase signal at the time of the correlation peak by the phase rotation detecting means and one of the partial correlation values corresponding to the partial correlation value obtained from the quadrature signal at the time of the correlation peak are calculated. , And a phase rotation between a vector composed of the other partial correlation value acquired from the in-phase signal and the other partial correlation value acquired from the quadrature signal. Then, the phase rotation of the received signal is corrected based on the phase rotation detected by the correction unit.

Therefore, in the CDMA receiver according to the present invention, the phase error detection range can be substantially widened as in the case of the above-described phase correcting device for a CDMA reception signal according to the present invention. Even when the phase rotation of the received signal is relatively large, the phase rotation can be correctly corrected, and the phase rotation can be corrected using, for example, a symbol other than the pilot symbol.

[0043]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment according to the present invention will be described with reference to the drawings. Since the CDMA receiver according to the present invention applies the phase correction device for the CDMA reception signal according to the present invention to the receiver, in this example, an example of the CDMA receiver according to the present invention will be described. 2 shows an embodiment of a phase correction device for a CDMA reception signal according to the present invention.

FIG. 1 shows an example of a CDMA receiver according to the present invention. The CDMA receiver includes a voltage-controlled oscillator 1 for outputting a signal (carrier) and a quadrature detector 2 for performing quadrature detection. And A / D for performing analog-digital conversion
Converter 3, a correction unit (AFC circuit unit) C1 for correcting the phase rotation of the received signal, a path extracting unit 11 for outputting a despread symbol at the time of path timing (a received symbol after despreading), and a despread symbol Demodulates and decodes data from
A demodulation unit 12 for making a determination or the like is provided.

Here, the correction section C1 corresponds to, for example, an example of a phase correction apparatus for a CDMA reception signal according to the present invention. The correction section C1 generates a spread code used in a transmission channel. Spreading code generator 4 and matched filter (MF) 5 for calculating despreading and partial correlation values
A complex conjugate multiplier 6 for performing complex conjugate multiplication, a path timing detection unit 7 for detecting path timing, an Arctan operation unit 8 for performing arc tangent operation, and an averaging unit 9 for performing averaging processing. A frequency control unit 10 for controlling the voltage controlled oscillator 1 is provided.

The voltage controlled oscillator 1 has a function of oscillating a signal (carrier) and outputting the oscillated signal to the quadrature detector 2. The frequency of the signal output from the voltage controlled oscillator 1 can be changed under the control of the frequency control unit 10 described later.

The quadrature detection unit 2 receives a radio frequency band signal (RF signal) received by the CDMA system, inputs a carrier output from the voltage controlled oscillator 1, and uses the carrier to generate the received signal. Is converted (down-converted) into an analog baseband in-phase signal and a quadrature signal and output to the A / D converter 3. In this example, by the function of the quadrature detection unit 2,
Quadrature detection means for detecting an in-phase signal and a quadrature signal from a received signal using a signal output from the oscillator is configured.

The A / D converter 3 converts an in-phase signal or a quadrature signal which is an analog baseband signal input from the quadrature detector 2 into a digital signal, and
It has the function of outputting to The code generation unit 4 includes a spread code for an in-phase signal (spread code for an in-phase signal) and a spread code for an orthogonal signal (a spread code for an orthogonal signal) used in a transmission channel.
Are output to the matched filter 5 as spreading codes for reference. In addition, as the spreading code for the in-phase signal and the spreading code for the orthogonal signal, for example, the same spreading code may be used, or different spreading codes may be used.

The matched filter 5 has a function of correlating the in-phase signal and the quadrature signal input from the A / D converter 3 with the respective reference spreading codes input from the code generator 4. It has a function of outputting the correlation value of one spreading code (one symbol) as a despread signal to the path timing detecting unit 7 and the path extracting unit 11 and outputting the selected partial correlation value to the complex conjugate multiplier 6. are doing.

Here, a detailed configuration example of the above-described matched filter 5 of the present embodiment is shown with reference to FIG. FIG. 2 shows a configuration example of the matched filter 5 according to the present embodiment and a complex conjugate multiplier 6.
And a path timing detection unit 7, an Arctan operation unit 8, and an averaging unit 9. As shown in the figure, the matched filter 5 of this example includes an in-phase processing unit Z1 for processing an in-phase signal, an orthogonal processing unit Z2 for processing an orthogonal signal,
A selector S for selecting and outputting a partial correlation value in accordance with an external correlation vector selection signal.

The in-phase processing section Z1 stores an in-phase register R1 (in this example, the number of taps is n) for storing an in-phase signal input from the A / D converter 3, and an in-phase spreading code. An in-phase shift register (not shown);
A plurality (n in this example) of multipliers J1 to Jn for multiplying the in-phase signal stored in the in-phase register R1 and the in-phase spreading code stored in the in-phase shift register, and a plurality of these multipliers A plurality of adders K1 to K9 for adding the results of multiplication by the devices J1 to Jn in a tournament manner are provided.

The in-phase register R1 has a function of storing an in-phase signal for one spreading code (one symbol). In this example, the in-phase signal stored in the n taps is one spreading code. Minute signal. That is, the in-phase spreading code of the present example is configured by arranging n values (“0” values or “1” values). The in-phase shift register has n taps, for example, like the in-phase register R1, and has a function of sequentially shifting the in-phase spread code to be stored.

Each of the multipliers J1 to Jn is connected to an in-phase register R1.
, Corresponding to each of the taps, the value of the common-mode signal stored in each tap of the common-mode register R1 and the value of the common-mode spreading code stored in each tap of the common-mode shift register Has the function of multiplying by By this multiplication, n multiplication results are obtained.

The adders K1 to K9 are provided in a plurality of stages, for example, as shown in FIG.
It has a function of adding n multiplication results by 1 to Jn to the tournament formula. Specifically, the first-stage adder K
At 1 to K4, for example, the multiplication result of the first and second taps from the left of the in-phase register R1 shown in FIG. 2 is added by the adder K1, and the multiplication result of the third and fourth taps is added to the adder K1. K2, and the (n-1) -th and n-th tap multiplication results are added by the adder K4, so that (n / 2) addition results are obtained.

Similarly, the second-stage adders K5 and K6
Then, for example, the first-stage adders K1 to K shown in FIG.
4, the addition result by the first and second adders K1 and K2 from the left is added by the adder K5, and the addition result by the first and second adders K3 and K4 from the right is added by the adder K6. So that (n /
4) Addition results are obtained. Similarly, an addition result is obtained by the adder of each stage, and for example, 2
The adder (not shown) in the immediately preceding stage obtains four addition results, and the adders K7 and K8 in the immediately preceding stage from the final stage have 2 addition results.
Are obtained, and one adder is obtained in the adder K9 at the last stage.

Here, in general, when a signal modulated using a spreading code for n taps (chips) is despread by the spreading code, the sum of the multiplication results for u taps is calculated by the tournament method described above. And a partial correlation value for u taps are obtained, and the partial correlation value is a correlation value (1
It is known that the value (u / n symbol correlation value) is u / n times the symbol correlation value. Specifically, for example, 1
The (2 / n) symbol correlation value is output from each of the adders K1 to K4 of the stage, and similarly, the (1/4) symbol correlation value is output from each of the adders two stages before the last stage. Output from the adders K7 and K8 immediately before the last stage, (1
/ 2) The symbol correlation value is output, and the final stage adder K9
Outputs a one-symbol correlation value.

As shown in FIG. 1, in this example, the one-symbol correlation value output from the adder K9 at the last stage is input to the path timing detector 7 and the path extractor 11. Further, as shown in FIG. 2, in this example, the partial correlation values output from the adders K1 to K8 in stages other than the last stage are input to the selector S.

Similarly to the in-phase processing unit Z1, the quadrature processing unit Z2 has a register R2 for storing the quadrature signal input from the A / D converter 3 (in this example, the number of taps is n). ), A shift register (not shown) for storing the orthogonal spreading code, and a plurality (n in this example) for multiplying the orthogonal signal stored in the register R2 by the orthogonal spreading code stored in the shift register. ) Multipliers G,
A plurality of adders H for adding the multiplication results of the plurality of multipliers G in a tournament manner are provided. Note that, for the multiplier G and the adder H, only one of them is denoted by a sign (G, H), and the other is omitted.

Register R provided in orthogonal processing section Z2
2, the multiplier G, the adder H, and the like are the same as those provided in the above-mentioned in-phase processing unit Z1. As in the case of the in-phase processing unit Z1, the orthogonal processing unit Z2 uses the orthogonal processing unit Z2. The one-symbol correlation value obtained for the signal is output to the path timing detection unit 7 and the path extraction unit 11, and the partial correlation value obtained for the orthogonal signal is output to the selector S.

The selector S selects and combines a partial correlation value for an in-phase signal and a partial correlation value for an orthogonal signal obtained from the same signal portion, for example, according to a correlation vector selection signal input from the outside. This is output to the complex conjugate multiplier 6 as the first selected correlation vector, and the partial correlation value of the in-phase signal obtained from the adjacent signal part having the same length as the signal part and the part of the quadrature signal are obtained. It has a function of selecting and combining a correlation value and outputting this to the complex conjugate multiplier 6 as a second selected correlation vector.

Here, in this example, as a preferable mode,
The case where the selector S selects the (1/2) symbol correlation value is shown. Specifically, for example, the in-phase register R1
VL, the partial correlation value obtained from the right half is denoted by VR, the partial correlation value obtained from the left half of the orthogonal register R2 is denoted by WL, and the partial correlation value obtained from the right half is denoted by WL. Assuming that the obtained partial correlation value is WR, the first selected correlation vector (VL, WL) and the second selected correlation vector (VR, WR) are output to the complex conjugate multiplier 6. Note that these vectors are represented by XY orthogonal coordinates, VL and VR corresponding to the X coordinate represent components for the in-phase signal, and WL and WR corresponding to the Y coordinate represent components for the orthogonal signal. Is represented.

The above-described correlation vector selection signal is output from a control unit that controls each process performed in, for example, a CDMA receiver. As a method of specifying which partial correlation value is to be selected by the selector S, the correlation vector selection signal does not necessarily have to be used as in this example. For example, which partial correlation value is to be selected is determined by the selector. It is also possible to use a mode or the like preset in S.

In this embodiment, two adjacent signal portions having the same length are selected from the in-phase signals for one spread code by the functions of the in-phase processing section Z1, the orthogonal processing section Z2, and the selector S. , And obtains a partial correlation value between each selected signal portion and a spreading code corresponding to each signal portion.
A part for selecting two signal parts corresponding to each of the two signal parts from the orthogonal signals for the spread codes, and obtaining a partial correlation value between the selected signal parts and the spread codes corresponding to the respective signal parts. A correlation value acquisition unit is configured.

In this embodiment, the in-phase processing unit Z
1 or the orthogonal processing unit Z2 obtains a correlation value (1 symbol correlation value) between the in-phase signal or the quadrature signal and the spreading code, and despreads the in-phase signal or the quadrature signal to obtain the in-phase signal or the quadrature signal. Despreading means for despreading the orthogonal signal with a corresponding spreading code is provided.

The complex conjugate multiplier 6 has a function of performing complex conjugate multiplication of two selected correlation vectors input from the selector S, and outputting the multiplication result to the Arctan operation unit 8. Here, in such complex conjugate multiplication, a phase rotation vector (phase variation) between two selected correlation vectors is obtained as a multiplication result.

More specifically, in this example, for example, a phase rotation vector of the first selected correlation vector with respect to the second selected correlation vector is obtained as a multiplication result. If the value of this phase rotation is Δθ, , (Cos (Δθ), si
n (Δθ)). In this example, the phase rotation value Δθ is the amount of phase rotation due to the frequency error of the oscillator 1 at (１ ／) symbol time, that is, the first selected correlation vector obtained from the rear signal portion. Has a phase rotation Δθ at (１ ／) symbol time applied to the second selected correlation vector obtained from the preceding signal portion.

The path timing detecting section 7 detects a timing position at which the one-symbol correlation value input from the matched filter 5 reaches a peak as a path timing, and sends the detected path timing to the Arctan calculating section 8 and the path extracting section 11. It has a function to output. In general,
When a peak appears in one symbol correlation value (1/2)
Peaks also appear in the symbol correlation value, (1/4) symbol correlation value, and the like.

The Arctan operation unit 8 calculates the phase rotation Δθ at the time of path timing (at the time of correlation peak) based on the phase rotation vector input from the complex conjugate multiplier 6 and the path timing input from the path timing detection unit 7. And outputs the result to the averaging unit 9. Note that, specifically, the phase rotation Δθ can be calculated by Expression 2.

[0069]

(Equation 2)

In the present embodiment, one of the partial correlation values obtained from the in-phase signal at the time of the correlation peak and one of the partial correlation values at the time of the correlation peak are obtained by the functions of the complex conjugate multiplier 6, the path timing detection unit 7, and the Arctan operation unit 8 described above. From the vector composed of the partial correlation value obtained from the quadrature signal and the corresponding one of the partial correlation values, and the other partial correlation value obtained from the in-phase signal and the other partial correlation value obtained from the quadrature signal, A phase rotation detecting means for detecting a phase rotation with respect to the constructed vector is configured.

The averaging unit 9 has a function of averaging the phase rotation Δθ input from the Arctan operation unit 8, and in this example, a plurality of phase rotations Δθ obtained at a plurality of consecutive correlation peaks are set. And outputs the average value to the frequency control unit 10. In the present example, such a function of the averaging unit 9 constitutes an average value detecting means for detecting an average value of a plurality of phase rotations. In order to perform such averaging, the phase rotation detecting means detects a plurality of phase rotations based on three or more vectors.

The frequency controller 10 calculates a frequency error of the voltage controlled oscillator 1 based on, for example, the average value of the phase rotation Δθ input from the averaging unit 9 and oscillates the voltage controlled oscillator 1 so that the error is eliminated. It has a function to feedback control the frequency. In the present example, this feedback control is performed by outputting a frequency control signal from the frequency control unit 10 to the voltage controlled oscillator 1, and the above-described control causes the above-described phase rotation Δθ to approach zero.

In the present embodiment, such a function of the frequency control section 10 constitutes a correcting means for correcting the phase rotation of the received signal based on the phase rotation detected by the phase rotation detecting means. As described above, the correction is performed by feedback-controlling the frequency of the signal output from the oscillator, and the correction is performed based on the average value detected by the average value detection means.

The path extracting unit 11 receives a one-symbol correlation value from the matched filter 5, inputs a path timing from the path timing detecting unit 7, latches the input one-symbol correlation value at the path timing, and The 1-symbol correlation value (despread symbol) obtained by
2 is provided.

The demodulation unit 12 has a function of demodulating, determining and decoding the despread symbol input from the path extraction unit 11, and outputting the decoded data. Further, the demodulation unit 12 of this example has a function of performing amplitude compensation processing of received signals (in-phase signals and quadrature signals) using pilot symbols or the like, or fading in a short period of time (for example, without extending over a plurality of frames). It has a function of compensating for the generated phase rotation. Note that the correction unit C1 provided in the CDMA receiver of the present example is mainly suitable for compensating a constant rotation for a relatively long time (for example, over a plurality of frames).

Next, the CDMA according to the present embodiment having the above-described configuration will be described.
4 shows an example of processing performed by a receiver. That is, C
Radio frequency band signal (RF
Signal) is input to the quadrature detection unit 2, and the carrier output from the voltage controlled oscillator 1 is input to the quadrature detection unit 2, and the quadrature detection unit 2 uses the carrier to convert the received signal to the baseband signal. Downconvert to a phase signal and a quadrature signal.

The A / D converter 3 digitizes the in-phase signal and the quadrature signal down-converted by the quadrature detector 2 and outputs the digitized signal to the matched filter 5. As described above, the matched filter 5 performs despreading by correlating the in-phase signal or the quadrature signal input from the A / D converter 3 with the reference spreading code, thereby obtaining the in-phase signal or the quadrature signal. The one-symbol correlation value is output to the path timing detection unit 7 and the path extraction unit 11, and the two selected correlation vectors are output to the complex conjugate multiplier 6.

The path timing detector 7 detects the path timing based on the one-symbol correlation value input from the matched filter 5, and determines the detected path timing as Arc.
Output to the tan operation unit 8 and the path extraction unit 11. The path extraction unit 11 latches the matched filter output (one symbol correlation value) at the time of the path timing and outputs it as a despread symbol, and the demodulation unit 12 demodulates the despread symbol and reproduces data.

As described above, the complex conjugate multiplication unit 6
, The Arctan operation unit 8 and the averaging unit 9 calculate the average value of the phase rotation Δθ of the received signal (the in-phase signal and the quadrature signal) at the time of the path timing, and the frequency control unit 10 calculates the average value of the received signal based on the average value. Correct the phase rotation.

As described above, the CDMA receiver of this embodiment receives a signal transmitted by the CDMA method, performs quadrature detection on the received signal using the signal (carrier) output from the oscillator 1, and detects the signal. When performing despreading or the like by correlating an in-phase signal and a quadrature signal with a spreading code, as described above, a phase rotation Δθ is detected based on a partial correlation value for a signal portion shorter than one spreading code, and Automatic control of the oscillation frequency of the oscillator 1 based on the phase rotation Δθ (AF
C) to correct the phase rotation of the received signal.

Therefore, in the CDMA receiver of this embodiment, if the value of the phase rotation between the two selected correlation vectors (1/2 symbol time in this example) is within ± π, the phase rotation of the received signal is Can be correctly corrected, and in this way, the error detection range of the phase (the error range in which the detection can be compensated) can be substantially widened. For this reason,
Even when the phase rotation of the received signal is relatively large, the phase rotation can be correctly corrected, whereby the characteristics of demodulated data and the like are greatly deteriorated due to, for example, the phase rotation caused by the accuracy of the oscillator 1. Can be prevented. Further, in the CDMA receiver of this example, for example, the phase rotation can be corrected using symbols other than the pilot symbols.

In the CDMA receiver of this embodiment, since the phase rotation of the received signal is corrected based on the average value of the detected phase rotation Δθ, for example, the accuracy of detecting the phase rotation Δθ is slightly deteriorated by noise. Even if it is, the influence of the deterioration can be reduced by averaging, and the accuracy of the phase correction can be improved. Also, the CDM of this example
In the A receiver, since the partial correlation value acquiring means for acquiring the partial correlation value and the despreading means for performing despreading are constituted by a common circuit, the apparatus can be simplified.

In this example, as described above, CDMA
The receiver has been described as an example.
The same applies to the phase correction device for the A reception signal.
When the phase rotation of the received signal is corrected using the in-phase signal and the quadrature signal detected from the signal received by the method using the output signal of the oscillator, the detection range of the phase error is substantially widened, etc. As a result, it is possible to prevent the characteristics of demodulated data or the like from being significantly degraded due to phase rotation.

Next, a second embodiment according to the present invention will be described with reference to FIG. FIG. 3 shows an example of a CDMA receiver according to the present invention.
The configuration is the same as that of the CDMA receiver shown in the first embodiment except that the configuration for correcting the phase rotation of the received signal using the detected phase rotation Δθ is different.

The CDMA receiver of this embodiment includes an oscillator 21 for outputting a signal (carrier), a correction unit C2 for correcting the phase rotation of the received signal, etc., and the CDM shown in the first embodiment.
A quadrature detector 22 similar to that provided in the A receiver, A
A / D converter 23, a path extraction unit 31, and a demodulation unit 32 are provided. Note that the oscillator 21 of the present example does not necessarily have to have a variable oscillation frequency.

The correcting unit C2 includes a frequency error correcting unit 30 for correcting the phase rotation of the despread symbol,
A code generation unit 24, a matched filter 25, a complex conjugate multiplier 26, a path timing detection unit 27, an Arctan operation unit 28, and an averaging unit 29 similar to those provided in the correction unit C1 shown in the embodiment are provided. ing.

In this embodiment, the CDM shown in the first embodiment is used.
A description of the same parts as the configuration of the A receiver is omitted,
Hereinafter, the configuration of the frequency error correction unit 30 which is different from the configuration of the CDMA receiver shown in the first embodiment will be described. That is, in this example, the frequency error correction unit 30 is provided between the path extraction unit 31 and the demodulation unit 32,
The average value of the phase rotation Δθ calculated by the averaging unit 29 is input to the frequency error correction unit 30.

In this example, the despread symbol output from the path extraction unit 11 includes a phase rotation, and such a despread symbol is input to the frequency error correction unit 30. The frequency error correction unit 30 corrects the phase rotation of the despread symbol input from the path extraction unit 31 based on the average value of the phase rotation Δθ input from the averaging unit 29, and sends the corrected despread symbol to the demodulation unit 32. It has a function to output. Specifically, for example, when the (1/2) symbol correlation value is used as in the case of the first embodiment, (1/1)
2) By applying a phase rotation of about -Δθ to the despread symbol in the symbol time, the phase rotation (phase shift) of the despread symbol can be made close to zero.

In this example, such a frequency error correction unit 3
The function of 0 constitutes a correcting means for correcting the phase rotation of the received signal based on the phase rotation detected by the phase rotation detecting means. In this example, the correcting means calculates the average value of the phase rotation detected by the average value detecting means. Correction based on
Further, the phase rotation of the received signal is corrected by correcting the phase rotation of the despread signal (in the present example, the above-described despread symbol).

As described above, also in the CDMA receiver of this embodiment, the phase error detection range can be substantially widened, for example, as in the case of the CDMA receiver shown in the first embodiment. Thus, it is possible to prevent the characteristics of the demodulated data from being greatly deteriorated by the phase rotation. Further, the same effect can be obtained with the phase correction device for a CDMA reception signal according to the present invention.

Here, in the above-described first and second embodiments, as a preferable mode for improving the accuracy of the phase correction, the phase rotation Δθ of the received signal is calculated using the (）) symbol correlation value. Although the mode in which the detection is performed and the correction is performed has been described, a mode in which the phase rotation Δθ of the received signal is detected and corrected using, for example, a (1/4) symbol correlation value may be used.

The reason why the accuracy of the phase correction is relatively improved when the (1/2) symbol correlation value is used is as follows.
This is because the signal-to-noise ratio (S / N ratio) is improved because the symbol correlation value is larger than the (1/4) symbol correlation value or the like. If such an S / N ratio is not considered, (1)
/ 4) (1/2) when symbol correlation value or the like is used
As compared with the case where the symbol correlation value is used, the pull-in range of the frequency error (phase error detection range) can be substantially widened. That is, for example, when a (1/4) symbol correlation value or the like is used, if the phase rotation at (1/4) symbol time or the like is within ± π, the phase rotation of the received signal can be correctly corrected. , (1/2) symbol correlation value is wider than in the case of using the correlation value.

Thus, as an example, when the phase rotation of the received signal is relatively large, the phase rotation of the received signal is roughly corrected by correction using (1/4) symbol correlation value or the like. It is also preferable to use a mode in which when the phase rotation of the signal becomes relatively small, the mode is switched to the correction using the (1/2) symbol correlation value to correct the phase rotation of the received signal with high accuracy.
The method for correcting the phase rotation of the received signal using the detected phase rotation Δθ is not particularly limited, and the point is that the phase rotation of the received signal due to an error can be made close to zero.

The modulation scheme used for communication between the CDMA transmitter and the CDMA receiver is not particularly limited, and various schemes such as a PSK modulation scheme and an amplitude modulation scheme may be used. Also, the present invention is not necessarily applied to a CDMA transmitter and a CDM such as a QPSK modulation system.
It is not necessary to apply the present invention to a CDMA receiver of a system in which an in-phase signal and a quadrature signal are simultaneously communicated with the A receiver. For example, a single-phase signal (in-phase signal or CD of the system in which the quadrature signal is transmitted
It can also be applied to MA receivers.

Specifically, for example, even when a signal of only one phase is transmitted from the CDMA transmitter, the signal may be rotated in phase when passing through the radio section. In such a case, if the present invention is applied to the CDMA receiver to perform the phase correction as shown in the first and second embodiments, the CDMA receiver can receive the one-phase signal received. The phase rotation can be accurately corrected.

In the first and second embodiments,
The mode in which the averaging units 9 and 29 average the phase rotation Δθ of the received signal at the time of a plurality of continuous correlation peaks has been described. For example, the phase rotation of the received signal is determined using (て) symbol correlation value or the like. In the case of correction, three or more vectors can be obtained from received signals (in-phase signal and quadrature signal) for one spreading code, and two or more phase rotations Δθ are detected using these vectors. You can also. In addition, when the detection accuracy of the phase rotation Δθ is not so much affected by noise or the like, the detected phase rotation Δθ need not always be averaged.

The phase correction of the CDMA reception signal shown in the first and second embodiments is performed, for example, by controlling the processor by executing a control program in a hardware resource including a processor and a memory. And each functional unit for executing the processing may be configured as an independent hardware circuit.

[0098]

As described above, the CD according to the present invention is
According to the phase correction device for the MA reception signal, the in-phase signal and the quadrature signal detected by using the output signal of the oscillator from the signal received by the CDMA method are used, for example, as shown in the above-described embodiment. Since the phase rotation (phase shift) of the received signal is detected based on the signal and the partial correlation value of the quadrature signal, it is possible to substantially widen the phase error detection range and the like. For example, it is possible to prevent data characteristics from being significantly degraded by phase rotation.

In the CDMA received signal phase correction apparatus according to the present invention, a plurality of phase rotations are detected and averaged,
Since the phase rotation of the received signal is corrected based on the average value, for example, even if the accuracy of detecting the phase rotation is slightly deteriorated due to noise, the influence of the deterioration is reduced and the phase correction is performed. Accuracy can be improved.

Further, according to the CDMA receiver according to the present invention, when the signal transmitted by the CDMA system is received and the received signal is subjected to quadrature detection or the like using the signal output from the oscillator, the CDMA receiver according to the present invention described above. Since the phase rotation of the reception signal is corrected by the same processing as that of the phase correction device for the CDMA reception signal, the error detection range of the phase can be substantially widened as described above.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a CDMA receiver according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration example of a matched filter.

FIG. 3 is a diagram illustrating an example of a CDMA receiver according to a second embodiment of the present invention.

FIG. 4 is a diagram illustrating an example of a communication frame.

FIG. 5 is a diagram illustrating a configuration example of a conventional CDMA receiver.

FIG. 6 is a diagram for explaining phase rotation of a received signal.

FIG. 7 is a diagram illustrating an example of a phase fluctuation amount.

FIG. 8 is a diagram for explaining a conventional problem.

[Explanation of symbols]

1,, 21..oscillator, 2,22..quadrature detector,
3, 23 ··· A / D converter, 4, 24 · · · code generator, 5, 25 · · matched filter, 6, 26 · · · ·
Complex conjugate multiplier, 7, 27... Path timing detector,
8, 28 ··· Arctan operation unit, 9, 29 · · · average unit, 10 · · · frequency control unit, 11, 31 · · · path extraction unit, 12, 32 · · · demodulation unit, 30 · · · frequency error correction unit, C1, C2... Correction section, R1, R2... Register, Z1... In-phase processing section, Z2... Quadrature processing section, J1 to Jn, G... Multiplier, K1 to K9, H.
Adder, S-selector,

Claims (5)

[Claims] 1. A CDMA system for correcting a phase rotation of a received signal by using an in-phase signal and a quadrature signal detected from a signal received by a CDMA method using an output signal of an oscillator.
A phase correction device for a received signal, wherein two adjacent signal portions having the same length are selected from the detected in-phase signals for one spreading code, and the selected signal portions correspond to the respective signal portions. A partial correlation value with the spreading code is obtained, and two signal portions corresponding to each of the two signal portions are selected from the detected orthogonal signals of one spreading code, and the selected signal portions and the respective signal portions are selected. A partial correlation value acquiring means for acquiring a partial correlation value between the signal portion and the corresponding spread code; and a partial correlation value acquired from the in-phase signal at the time of the correlation peak and the portion acquired from the quadrature signal at the time of the correlation peak A vector composed of a correlation value and one corresponding partial correlation value, and a vector composed of the other partial correlation value acquired from the in-phase signal and the other partial correlation value acquired from the quadrature signal. Phase rotation detection means, the detected and correction means for correcting the phase rotation of the received signal based on the phase rotation, the phase correcting apparatus of the CDMA received signal, comprising the detecting phase rotation. 2. The phase correction device for a CDMA reception signal according to claim 1, wherein said phase rotation detecting means detects a plurality of phase rotations from three or more vectors, and detects an average value of the plurality of phase rotations. An apparatus for correcting a phase of a CDMA reception signal, comprising: average value detection means, wherein the correction means performs correction based on the average value detected by the average value detection means. 3. The CDMA according to claim 1 or 2,
A phase correction device for a CDMA reception signal, wherein the correction unit performs the correction by performing feedback control on a frequency of a signal output from the oscillator. 4. The CDMA according to claim 1 or 2,
A phase correction device for a received signal, comprising: despreading means for despreading the in-phase signal and the quadrature signal with corresponding spreading codes, wherein the correction means corrects a phase rotation of the despread signal. A phase correction device for a CDMA reception signal, wherein the phase correction of the reception signal is corrected. 5. A CDMA receiver that receives a signal transmitted by a CDMA system and performs quadrature detection on the received signal using a signal output from an oscillator. Quadrature detection means for detecting a phase signal and a quadrature signal; selecting two adjacent signal portions having the same length from the detected in-phase signals for one spreading code, and selecting each selected signal portion and the corresponding signal portion And a partial correlation value with the corresponding spreading code is obtained, and two signal portions corresponding to each of the two signal portions are selected from the detected orthogonal signals of one spreading code, and each of the selected signal portions is A partial correlation value acquiring means for acquiring a partial correlation value between each of the signal portions and the corresponding spreading code; and a partial correlation value acquired from the in-phase signal at the time of the correlation peak and the orthogonal signal at the time of the correlation peak. A vector composed of the partial correlation value obtained from the signal and one of the corresponding partial correlation values, the other partial correlation value obtained from the in-phase signal, and the other partial correlation value obtained from the quadrature signal. A CDMA receiver, comprising: a phase rotation detecting unit that detects a phase rotation between the received signal and a correction vector that corrects the phase rotation of the reception signal based on the detected phase rotation.