JPH0795130A - Spread spectrum signal receiver - Google Patents

Abstract

PURPOSE:To decide a signal in an excellent way even when the level of an interference wave is high by providing a means eliminating an interference wave component included in an inverse spread signal of a desired wave with an inverse spread signal of the interference wave satisfying a specific condition. CONSTITUTION:A reception signal subjected to spread spectrum processing is inputted from an input terminal 40. A multiplex inverse spread circuit 41 inputs the reception signal and uses a desired wave and a spread code of an interference wave to extract plural inverse spread signals. An inverse spread signal selection circuit 42 selects and outputs a signal satisfying a specific condition among plural inverse spread signals. Furthermore, a selection information signal representing which inverse spread signal is selected is inputted to a linear synthesis circuit 43. The linear synthesis circuit 43 multiplies a weight coefficient with the selected inverse spread signal to synthesize the signals thereby eliminating an interference wave component from the inverse spread signal of the desired wave to provide plural interference wave eliminated inverse spread signals. A detector 44 decides the signal by using the plural interference wave eliminated inverse spread signals of the desired wave and outputs a decision signal from an output terminal 45.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is used in digital wireless communication. In particular, it relates to a technique for removing an interference wave in a received signal in a spread spectrum communication system.

[0002]

2. Description of the Related Art In recent years, a CDMA (Code Division Multiple Access) system using a spread spectrum system has been studied in order to effectively use frequencies in digital mobile communication. Although it is affected by frequency selective fading in a multi-wave transmission path such as a mobile propagation path, the RA is a spread spectrum signal receiver suitable for such a propagation path.
There is a KE receiver.

The structure of a conventional RAKE receiver will be described with reference to FIG. FIG. 10 is a block diagram of a conventional device. The received signal is input from the input terminal 1. CDM
In the A system, the same frequency band is used by stations having different spreading codes. Therefore, this received signal has a desired wave that has been band-spread with a spreading code such as a PN code and an interference wave that has been spread with a different spreading code. Since the correlation between different spreading codes is low, in order to demodulate the desired wave, the same spreading code as that of the desired wave is used to obtain the correlation with the received signal.
That is, it must be despread. Despreading circuit 2
Performs despreading using the spreading code of the desired wave output from the spreading code generation circuit 3 for the received signal. The output of the despreading circuit 2 is a plurality of despread signals separated for each path of the multipath propagation path. The level selection circuit 4 selects one having a higher level from the plurality of despread signals. The detection circuit 5 makes a signal determination using the selected despread signal and outputs a determination signal from the output terminal 7. Here, the despreading circuit 2 and the spreading code generation circuit 3 correspond to despreading means, and the level selection circuit 4 and the detection circuit 5 are components of the detector 6 and correspond to detection means.

Next, the configuration of the despreading circuit 2 will be described with reference to FIG. FIG. 11 is a block diagram of a conventional despreading circuit 2. The received signal and the spread code of the desired wave are input from the input terminals 8 and 19, respectively. Complex multiplier 9
The received signal is multiplied by the spread code and input to the integration circuit 13. This operation corresponds to the correlation between the received signal and the spreading code, that is, despreading. A spreading code such as a PN code has a strong autocorrelation property, and a signal cannot be extracted in the process of despreading unless the timing of the spreading code in transmission / reception matches. Now, assuming that the timings of the spreading code of the preceding wave component and the spreading code of the desired wave in the multiple wave propagation path match, the path component of the preceding wave is extracted from the integrating circuit 13 and output from the output terminal 16 as a despread signal. To be done. Similarly, the complex multipliers 10 and 20 output the T output from the delay circuits 11 and 12, respectively.
_c , 2T _c (T _c : clock cycle of spread code) The delayed spread code is multiplied and input to the integration circuits 14 and 15, respectively. Assuming that the timings of the spread code of the delayed wave component and the delayed spread code in the multiple wave propagation path are the same, T _c and 2T _c are output from the integrating circuits 14 and 15, respectively.
The path component of the delayed delayed wave is extracted and output from the output terminals 17 and 18 as a despread signal.

Next, the structure of the level selection circuit 4 will be described with reference to FIG. FIG. 12 shows a conventional level selection circuit 4
It is a block configuration diagram of. The despread signal is input from the input terminals 21 to 23. The square operation circuits 28 to 30 output the level signals of the respective despread signals and input them to the level detection circuit 27. The level detection circuit 27 controls the selection circuit 24 so as to select only the despread signal whose level signal exceeds a certain threshold. The selection circuit 24 outputs the selected despread signal from the output terminals 25 and 26.

Next, the structure of the detection circuit 5 will be described with reference to FIG. FIG. 13 is a block diagram of a conventional detection circuit 5. The despread signal selected from the input terminals 31 and 34 is input. The complex multipliers 33 and 36, and the despread signal and the delay circuit 32 and 35
The despread signal delayed by the symbol period T is multiplied and output. This operation corresponds to differential detection. The results of this multiplication, that is, the differential detection outputs, are added up by the adder 37. The decision circuit 38 makes a signal decision by hard decision based on the output signal of the adder 37, and outputs a decision signal from the output terminal 39.

[0007]

In such a CDMA system, the same frequency band is used by stations having different spreading codes. Since the correlation between different spreading codes is low, the signal of another station, that is, the interference wave, can be regarded as a low-level noise component in the despreading process if the level is low. However, when the level of the interference wave is very high, a high level interference wave component remains in the despread signal of the desired wave, and the transmission characteristics are significantly deteriorated. An interference canceller function is required to suppress this deterioration, but this function does not work well in the conventional spread spectrum receiver RAKE receiver shown in FIG. Therefore, when the level of the interference wave is very high, there is a drawback that the transmission characteristics are significantly deteriorated.

The present invention has been made against such a background, and an object of the present invention is to provide a spread spectrum signal receiver capable of performing a good signal determination even in a situation where the level of an interference wave is high.

[0009]

According to the present invention, an inverse terminal for extracting a despread signal of a desired wave by using an input terminal to which a spread spectrum received signal is inputted and the received signal and a spreading code of a desired wave. A spread spectrum signal receiver including a spread circuit and a detector that determines a signal output from the despread circuit.

Here, a feature of the present invention is that the despreading circuit includes means for extracting a despread signal of the interference wave by using a spreading code of the interference wave. An interference wave removing means is inserted between the device and the device, and the interference wave removing means selects a despread signal of the interference wave satisfying a specific condition from the despread signal of the interference wave, and the specific condition is satisfied. And a means for removing an interference wave component included in the despread signal of the desired wave by the despread signal of the interference wave.

It is preferable that the despreading circuit includes means for extracting a despread signal for each of the desired wave and the interference wave that have passed through a plurality of paths.

The selecting means selects a despread signal of the interference wave having a strong correlation with the despread signal of the desired wave from the despread signal of the interference wave as a despread signal of the interference wave satisfying the specific condition. It is desirable to prepare. Also, the means for selecting, as the despread signal of the interference wave satisfying the specific condition, the despread signal of the interference wave to be despread using the spreading code having a strong correlation with the spreading code used for despreading the desired wave. It is also possible to adopt a configuration including means for selecting.

The despreading circuit, the selecting means, and the removing means are provided for each diversity branch, and the detector selects the output of the removing means provided for each diversity branch. It may be configured to include a signal determination unit.

The despreading circuit outputs the signal power of the interference wave component contained in the despread signal of the desired wave and the despread signal power of the desired wave, and the despreading circuit according to the output of the comparing means. Means for selecting either the despread signal of the desired wave or the despread signal of the desired wave from which the interference wave component output from the removing means is removed, and a signal according to the signal output from the selecting means It may be configured to include a determining unit. Further, the selecting means may be provided for each diversity branch, and the detector may be configured to include a means for determining a signal by selecting an output of the selecting means.

[0015]

The despread signal of the desired wave and the despread signal of the plurality of interference waves are extracted from the spread spectrum received signal by using the spreading codes of the desired wave and the interference wave. An interference wave component can be removed from the despread signal of the desired wave by selecting one from the despread signals of the interference wave that satisfies a specific condition and multiplying the despread signal of the desired wave by a weighting coefficient and combining. . Signal determination is performed using this interference wave despread signal of the desired wave.

The despread signal of the interference wave satisfying the specified condition is, for example, the despread signal of the interference wave having a strong correlation with the despread signal of the desired wave among the despread signals of the plurality of interference waves. It is also possible to use a despread signal of an interference wave satisfying the above condition, or a despread signal of an interference wave that is despread using a spreading code having a strong correlation with the spreading code used for despreading the desired wave. It can also be a despread signal of the wave.

As a result, good signal determination can be performed even in a situation where the level of the interference wave is high.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram of a first embodiment device of the present invention. FIG. 2 is a block diagram of the multiple despreading circuit 41 of the first embodiment of the present invention. FIG. 3 is a block diagram of the despread signal selection circuit 42 according to the first embodiment of the present invention. FIG. 4 is a block diagram of the linear synthesis circuit 43 of the first embodiment of the present invention. FIG. 5 is a block diagram of the detection circuit of the detector 44. FIG. 6 is a block diagram of a detection circuit including branch metric calculation circuits 157 and 159. FIG. 7 shows branch metric calculation circuits 157 and 159.
It is a block configuration diagram of.

According to the present invention, the despread signal of the desired wave is extracted using the input terminal 40 to which the spread spectrum received signal is input and the received signal and the spreading code of the desired wave. This is a spread spectrum signal receiver including a desired wave despreading circuit 47 in the despreading circuit 41 and a wave detector 44 for determining a signal output from the desired wave despreading circuit 47.

Here, the feature of the present invention is that the multiple despreading circuit 41 uses the spreading code of the interference wave to extract the despreading signal of the interference wave. An interference wave removing section 190 as an interference wave removing means is interposed between the multiple despreading circuit 41 and the detector 44.
0 is a despread signal selection circuit 42 as a means for selecting a despread signal of an interference wave satisfying a specific condition from the despread signal of an interference wave, and a despread signal of a desired wave by a despread signal of an interference wave satisfying the specific condition. The linear combining circuit 43 is provided as means for removing the interference wave component included in the spread signal. Desired wave despreading circuit 47 includes means for extracting a despread signal for each desired wave that has passed through a plurality of paths. Similarly, the interference wave despreading circuits 49 and 5
1 includes means for extracting despread signals for each of the interference waves that have passed through a plurality of paths.

Next, the operation of the first embodiment of the present invention will be described. The spread spectrum received signal is input from the input terminal 40. The multiple despreading circuit 41 receives this received signal as an input and extracts a plurality of despread signals using the spreading codes of the desired wave and the interference wave. The despread signal selection circuit 42 selects and outputs one that satisfies a specific condition from a plurality of despread signals. Also, a selection information signal indicating what kind of despread signal has been selected is input to the linear synthesis circuit 43. The linear combination circuit 43 removes the interference wave component from the despread signal of the desired wave by multiplying the selected despread signal by a weighting coefficient and combines them to output a plurality of interference-removed despread signals of the desired wave. To do. The detector 44 performs signal determination using a plurality of interference removal despread signals of the desired wave, and outputs the determination signal from the output terminal 45.

The operation of the multiple despreading circuit 41 will be described in more detail with reference to FIG. The received signal is input from the input terminal 46. The desired-wave despreading circuit 47 despreads the received signal using the desired-wave spreading code output from the desired-wave spreading code generation circuit 48, and outputs the despread signal of each desired wave for each of a plurality of paths from the output terminals 53 to 55. Output. Interference wave despreading circuit 49
And 51 despread the received signal using different spreading codes of the interference waves output from the interference wave spreading code generation circuits 50 and 52, respectively, and output the interference waves for each path from the output terminals 56 to 58 and the output terminals 59 to 61. The despread signal of is output.

The operation of the linear synthesis circuit 43 will be described in more detail with reference to FIG. A plurality of despread signals selected from the input terminals 62 to 67 are input. The despread signals input from the input terminal 62 are multiplied by different weighting factors in the complex multipliers 68 to 70. Here, the complex multiplier 68-
Reference numeral 70 is a component of the multiplex multiplier 71. Similarly, the despread signals input from the input terminals 63 to 67 are input to the multiplexing multipliers 72 to 76, respectively, and are multiplied by the weighting coefficient. The adder 77 combines the outputs of the multiplex multipliers 71 to 76 and outputs the combined output from the output terminal 80. Adder 7
8 and 79 perform the same operation, and output the addition result to output terminal 8
Output from 1 and 82. The selection information signal output from the despread signal selection circuit 42 is input from the input terminal 84.
This selection information signal is a signal indicating what kind of despread signal has been selected, and is input to the weighting coefficient memory 83. The weighting coefficient memory 83 selects and outputs one from a plurality of sets of weighting coefficients stored in advance according to the selection information signal. This weighting coefficient is used for the desired wave spreading code generating circuit 48 and the interference wave spreading code generating circuit 5.
0 and 52 are the elements of the spread code of the desired wave and the interference wave output by 0 and 52, the correlation matrix of their delayed spread codes, and their inverse matrix. Therefore, it can be calculated in advance and stored in the weighting coefficient memory 83.

The interference wave component included in the despread signal of the desired wave is generated because the correlation between the desired wave and the spread code of the interference wave is not "0", and the despread signal of the interference wave has this correlation coefficient. Is almost proportional to the product of. Therefore, if the despread signals of the desired wave and the interference wave are multiplied by the weighting factors and combined, the interference wave component can be removed from the despread signal of the desired wave, so that the signal can be judged well even when the level of the interference wave is high. You can

The structure of the detector 44 can be the same as that of the detector 6 of FIG. 10, but another structure is also possible. Another configuration is shown in FIG.
It will be described with reference to FIGS. The detector 44 is composed of a level selection circuit that selects one of the outputs of the linear synthesis circuit 43 whose level exceeds a certain threshold value, and a detection circuit that makes a signal determination based on the output of this level selection circuit. The level selection circuit is the same as that of the conventional example shown in FIG. The function of the level selection circuit can be added to the multiple despreading circuit. In this case, the detector 4
The level selection circuit of 4 is unnecessary.

The detection circuit shown in FIG. 4A has an input terminal 1
A plurality of interference wave elimination despread signals of desired waves selected from 34 and 138 are input. The complex multipliers 136 and 140 receive the interference wave elimination despread signal and the delay circuit 135.
In 139 and 139, the interference wave elimination despread signal delayed by one symbol period T of the modulated wave is multiplied by complex multipliers 136 and 140 and output. This operation corresponds to differential detection. The differential detection outputs are multiplied by tap coefficients in complex multipliers 137 and 141, respectively, and added in an adder 142.
The decision circuit 143 makes a signal decision by hard decision based on the output signal of the adder 142, and outputs a decision signal from the output terminal 144. The subtractor 145 outputs the difference between the input and output signals of the determination circuit 143, that is, the estimation error. The tap coefficient control circuit 146 receives the estimation error and the differential detection output, and is an RLS (Recursive Least Square: RLS) which is a recursive algorithm of the least square method so that the mean square of the estimation error is minimized.
Estimate the tap coefficient using the recursive least squares method) algorithm and output it. In this way, by controlling the tap coefficient, it is possible to remove a small amount of the interference wave component remaining in the interference wave removal despread signal of the desired wave. The LMS algorithm and Kalman filter can also be applied to this tap coefficient estimation algorithm.

The detection circuit shown in FIG. 4B has an input terminal 1
A plurality of interference wave elimination despread signals of desired waves selected from 34 and 138 are input. The complex multipliers 137 and 141 multiply the tap coefficients, and the adder 142 adds them. The decision circuit 143 makes a signal decision by hard decision based on the output signal of the adder 142, and outputs a decision signal from the output terminal 144. The subtractor 145 outputs the difference between the input and output signals of the determination circuit 143, that is, the estimation error. The tap coefficient control circuit 146 receives the estimation error and the outputs of the complex multipliers 137 and 141, and estimates and outputs the tap coefficient using the RLS algorithm so that the mean square of the estimation error is minimized. In this way, by controlling the tap coefficient, it is possible to remove a small amount of the interference wave component remaining in the interference wave removal despread signal of the desired wave. Further, maximum ratio combining of a plurality of interference wave-removing despread signals is possible, and transmission characteristics are improved. This tap coefficient estimation algorithm uses LM
The S algorithm and Kalman filter can also be applied.

The detection circuit shown in FIG. 5 receives a plurality of interference wave despread signals of the desired wave selected from the input terminals 134 and 138. Branch metric arithmetic circuit 1
57 and 159 are despread signals for removing interference waves of a desired wave,
The signal sequence candidate output from the maximum likelihood sequence estimation circuit 161 is input, and a branch metric that is likelihood information for the signal sequence candidate is output. Branch metric calculation circuit 15
The branch metrics output from 7 and 159 are added up by the adder 160 and output as a combined branch metric. The maximum likelihood sequence estimation circuit 161 calculates the cumulative sum of this combined branch metric as a log-likelihood function, and outputs the signal sequence candidate with the maximum log-likelihood function as a determination signal from the output terminal 144.

FIG. 6 shows a branch metric operation circuit 157.
And 159 shows the block configuration. The branch metric operation circuits 157 and 159 shown in FIG. 6A receive the interference wave elimination despread signal of the desired wave selected from the input terminal 163. The subtractor 164 is a complex multiplier 165.
Outputs the difference between the estimated signal output by and the despread signal with interference wave removed as an estimation error. The square calculation circuit 167 outputs a signal obtained by multiplying the square of the absolute value of the estimation error by a negative constant to the signal terminal 1
Output from 69 as a branch metric. A signal sequence candidate is input from the input terminal 168, and the complex multiplier 16
Reference numeral 5 multiplies the current signal candidate included in the signal sequence candidate by the tap coefficient and outputs the estimated signal. The tap coefficient control circuit 166 receives the estimation error and the current signal candidate, estimates the tap coefficient using the RLS algorithm so as to minimize the mean square of the estimation error, and outputs the tap coefficient. The LMS algorithm and Kalman filter can also be applied to this tap coefficient estimation algorithm.

The branch metric operation circuits 157 and 159 shown in FIG. 6B receive the interference wave elimination despread signal ys (k) of the desired wave selected from the input terminal 163. ys (k) is an L including delay circuits 171 to 173.
The interference wave elimination despread signal input to the shift register 188 of each stage and delayed for each T is output from the shift register 188. The present time k and the past interference wave elimination despread signal are input to the complex multipliers 174 to 178, and the input terminal 16
The signal sequence candidate {am (k)} inputted from 8 is inversely modulated. When the modulation method is PSK (Phase Shift Keying), the inverse modulation is equivalent to multiplying the complex conjugate of the signal sequence candidate {am (k)}, and here the primary modulation of the received signal is PSK. The complex multipliers 179 to 182 and the adder 183 calculate the linear combination of the demodulated past interference wave elimination despread signal and output it as an estimated signal of the demodulated current interference wave elimination despread signal. Subtractor 184
Outputs the difference between the demodulated current interference wave removal despread signal and this estimation signal as an estimation error. The squaring circuit 185 outputs a signal obtained by multiplying the square of the absolute value of the estimation error by a negative constant as a branch metric from the output terminal 169.

Next, the despread signal selection circuit 42 of the first embodiment of the present invention will be described with reference to FIG. FIG. 7 is a block diagram of the despread signal selection circuit 42 according to the first embodiment of the present invention. The despread signal of the desired wave is input from the input terminals 95 to 97, and the despread signal of the interference wave is input from the input terminals 98 to 103. The correlation calculation circuit 104 detects a despread signal having a strong correlation with the despread signal of the desired wave from the plurality of despread signals of the interference wave. The despread signal of the interference wave having a strong correlation is mixed with the despread signal of the desired wave as an interference wave component, and is a signal necessary for the interference wave removal performed by the linear synthesis circuit 43. Further, the correlation calculation circuit 104 controls the selection circuit 105 to output the despread signal having a strong correlation to the output terminals 110-1.
Output from 12. Also, a selection information signal indicating what kind of despread signal has been selected is output from the output terminal 106. The despread signal of the desired wave is output terminal 10 as it is.
Output from 7 to 109.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 8 is a block diagram of the despread signal selection circuit 42 according to the second embodiment of the present invention. Input terminals 113 to 11
The despread signal of the desired wave is input from 5. Further, despread signals of interference waves are input from the input terminals 116 to 121. The correlation calculation circuit 125 is used in the desired wave spreading code generation circuit 1
22 and the spreading code of the desired wave and the interference wave output from the interference wave spreading code generation circuits 123 and 124 are spread with a spreading code having a strong correlation with the spreading code of the desired wave from a plurality of despread signals of the interference wave. Detect the despread signal. The despread signal of these interference waves has a high possibility of being mixed as an interference wave component in the despread signal of the desired wave.
3 is a signal required for interference removal performed by the third embodiment. Further, the correlation calculation circuit 125 controls the selection circuit 126 to output the despread signal of the interference wave spread by the spreading code having a strong correlation with the spreading code of the desired wave from the output terminals 131 to 133. A selection information signal indicating whether the spread signal is selected is output from the output terminal 127. The despread signal of the desired wave is output from the output terminals 128 to 130 as it is.

Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 9 is a block diagram of a third embodiment device of the present invention. The third embodiment of the present invention is an extension of the first embodiment of the present invention to a diversity reception configuration. Here, the number of diversity branches is set to two. The spread spectrum received signal of the first diversity branch is input from the input terminal 85, and the spread spectrum received signal of the second diversity branch is input from the input terminal 89. In the first diversity branch, the multiple despreading circuit 8
6, a despread signal selection circuit 87 and a linear combination circuit 88 are installed, and in the second diversity branch, a multiple despread circuit 90, a despread signal selection circuit 91, and a linear combination circuit 9 are provided.
2 are installed. The outputs of the linear combination circuit 88 and the linear combination circuit 92 are a plurality of interference wave removal spread signals of the desired wave output for each diversity branch. Detector 9
3 performs signal determination using these interference wave elimination despread signals, and outputs a determination signal from the output terminal 94. Since the third embodiment of the present invention performs diversity reception, transmission characteristics are improved. It goes without saying that the despread signal selection circuit 42 of the second embodiment of the present invention can also be applied to the third embodiment of the present invention.

Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 10 is a block diagram of the device of the fourth embodiment of the present invention. The spread spectrum received signal is input from the input terminal 40. The multiple despreading circuit 41 receives this received signal as an input and extracts a plurality of despread signals using the spreading codes of the desired wave and the interference wave. Here, the multiple despreading circuit 41 corresponds to a despreading means. The despread signal selection circuit 42 selects and outputs one that satisfies a specific condition from a plurality of despread signals. Also, a selection information signal indicating what kind of despread signal has been selected is input to the linear synthesis circuit.
Here, the despread signal selection circuit 42 corresponds to the despread signal selection means. The linear synthesizing circuit 43 removes the interference wave component from the despread signal by multiplying the selected despread signal by a weighting coefficient and synthesizing the despread signal to obtain a plurality of interference-removing despreads of not only the desired wave but also the interference wave. Output a signal. Interference removal of interference wave In the despread signal, the interference wave component from other stations including the desired wave is removed. Here, the linear combination circuit 43 corresponds to an interference wave removing means. The control circuit 200 controls the selection circuit 201 based on the interference removal despread signal, and outputs one of the desired wave despread signal and the desired wave interference removal despread signal as the selection signal. Specifically, the ratio of the signal power of the interference wave component included in the despread signal of the desired wave to the despread signal power of the desired wave, that is, CIR, is calculated, and C
When the IR exceeds a certain threshold value, the despread signal of the desired wave is selected, and when it does not exceed the threshold value, the interference removal despread signal of the desired wave is selected. The control is performed in this manner because when the CIR is large, that is, when the signal power of the interference wave component is small, the noise power is amplified in the above-described interference removal process, so that the transmission characteristics deteriorate when the interference is removed. Here, the control circuit 200 and the selection circuit 201 correspond to selection means. The detector 6 makes a signal determination using this selection signal, and outputs a determination signal from the output terminal 7. Here, the detector 6 corresponds to a detecting means. The fourth embodiment of the present invention works well in both high and low levels of interference waves.

Next, a fifth embodiment of the present invention will be described with reference to FIG. FIG. 11 is a block diagram of the device of the fifth embodiment of the present invention. The fifth embodiment of the present invention is an extension of the fourth embodiment of the present invention to diversity reception. Here, the number of diversity branches is set to 2. The spread spectrum received signal of the branch 1 is input from the input terminal 85, and the spread spectrum received signal of the branch 2 is input from the input terminal 89. Multiple despreading circuits 86 and 90, despreading signal selection circuits 87 and 91, linear combination circuits 88 and 92, control circuits 300 and 400, and selection circuits 301 and 401 are installed for each diversity branch. The selection circuits 301 and 401 for each diversity branch output a selection signal. The detector makes a signal determination using these selection signals, and outputs a determination signal from the output terminal 94. Here, the detector 93 corresponds to a detecting means. Similar to the fourth embodiment of the present invention, it works well in both high and low interference wave levels.

[0036]

As described above, according to the present invention,
It is possible to realize a spread spectrum signal receiver that can make a good signal determination even when the level of the interference wave is high.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of an apparatus according to a first embodiment of the present invention.

FIG. 2 is a block configuration diagram of a multiple despreading circuit according to the first embodiment of the present invention.

FIG. 3 is a block configuration diagram of a linear synthesis circuit according to the first embodiment of the present invention.

FIG. 4 is a block configuration diagram of a detection circuit of a detector.

FIG. 5 is a block configuration diagram of a detection circuit including a branch metric calculation circuit.

FIG. 6 is a block configuration diagram of a branch metric operation circuit.

FIG. 7 is a block configuration diagram of a despread signal selection circuit according to the first embodiment of the present invention.

FIG. 8 is a block configuration diagram of a despread signal selection circuit according to a second embodiment of the present invention.

FIG. 9 is a block configuration diagram of an apparatus according to a third embodiment of the present invention.

FIG. 10 is a block configuration diagram of a fourth embodiment device of the present invention.

FIG. 11 is a block configuration diagram of a fifth embodiment device of the present invention.

FIG. 12 is a block diagram of a conventional example device.

FIG. 13 is a block diagram of a conventional despreading circuit.

FIG. 14 is a block configuration diagram of a conventional level selection circuit.

FIG. 15 is a block diagram of a conventional detection circuit.

[Explanation of symbols]

1, 8, 19, 21, 22, 23, 31, 34, 40,
46, 62-67, 84, 85, 89, 95-103,
113 to 121, 134, 138, 163, 168 Input terminal 2 despreading circuit 3 spreading code generating circuit 47 desired wave despreading circuit 48 desired wave spreading code generating circuit 49, 51 interference wave despreading circuit 50, 52 interference wave spreading code Generation circuit 4 Level selection circuit 5 Detection circuit 6, 44, 93 Detection device 7, 16-18, 25, 26, 39, 45, 53-6
1, 80-82, 94, 106-112, 127-13
3, 144, 186 output terminals 9, 10, 20, 33, 36, 68 to 70, 136, 1
37, 140, 141, 165, 174-182 Complex multipliers 11, 12, 32, 35, 135, 139, 171-1
73 Delay Circuit 13-15 Integration Circuit 24, 105, 126, 201, 301, 401 Selection Circuit 27 Level Detection Circuit 28-30 Square Operation Circuit 37, 77-79, 142, 160, 183 Adder 41, 86, 90 Multiple despreading circuit 38,143 Determining circuit 42,87,91 Despreading signal selecting circuit 43,88,92 Linear combining circuit 71-76 Multiplexing multiplier 83 Weighting coefficient memory 122 Desired wave spreading code generating circuit 123,124 Interfering wave spreading Code generation circuit 104, 125 Correlation calculation circuit 145, 164, 184 Subtractor 146, 166 Tap coefficient control circuit 157, 159 Branch metric calculation circuit 161 Maximum likelihood sequence estimation circuit 167, 185 Square calculation circuit 188 Shift register 190 Interference removal Part 200, 300, 400 control circuit

Claims (6)

[Claims] 1. An input terminal to which a spread spectrum received signal is input, a despreading circuit for extracting a despread signal of the desired wave using the received signal and a spreading code of the desired wave, and the despreading circuit. In the spread spectrum signal receiver including a detector for determining the output signal of the signal, the despreading circuit includes means for extracting the despread signal of the interference wave using the spreading code of the interference wave, Interference wave removing means is interposed between the spreading circuit and the detector, and this interference wave removing means selects means for selecting the despread signal of the interference wave satisfying a specific condition from the despread signal of the interference wave, A spread spectrum signal receiver comprising means for removing an interference wave component included in a despread signal of a desired wave by a despread signal of an interference wave satisfying the specific condition. 2. The selecting means selects, from the despread signal of the interference wave, the despread signal of the interference wave having a strong correlation with the despread signal of the desired wave, as the despread signal of the interference wave satisfying the specific condition. The spread spectrum signal receiver according to claim 1, further comprising means. 3. The despreading signal of an interference wave that despreads using a spreading code having a strong correlation with a spreading code used for despreading the desired wave, the selecting means reverses the interference wave that satisfies the specific condition. A means for selecting as a spread signal is provided.
The spread spectrum signal receiver described. 4. The despreading circuit, the selecting means, and the removing means are provided for each diversity branch, and the detector includes means for selecting a signal of the output of the removing means and determining a signal. A spread spectrum signal receiver according to any one of claims 1 to 3. 5. A means for comparing the signal power of the interference wave component included in the despread signal of the desired wave with the despread signal power of the desired wave, and an output from the despreading circuit according to the output of the comparing means. Means for selecting either the despread signal of the desired wave or the despread signal of the desired wave from which the interference wave component output from the removing means is removed, and a signal output from the selecting means Therefore, the spread spectrum signal receiver according to any one of claims 1 to 3, further comprising a signal judging means. 6. The spread spectrum signal receiver according to claim 5, wherein said selecting means is provided for each diversity branch, and said detector comprises means for selecting the output of said selecting means to determine a signal. .