JP2002118495A - Spread spectrum communication correlator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spread spectrum communication correlator capable of reducing power consumption by decreasing a circuit scale and completely realizing a correlation calculation of a reception base band signal. SOLUTION: The spread spectrum communication correlator comprises an adder, a subtracter for adding and subtracting an in-phase component and an orthogonal component of the reception base band signal, and a phase rotator for conducting a phase rotation of output results of the adder and the subtracter based on values of a reference diffusion code of the in-phase component and the orthogonal component to output demodulated results of the respective components. Thus, the circuit scale can be reduced, the power consumption can be reduced. A correlation calculation of the reception base band signal can be completely realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spread spectrum communication correlator for demodulating a received signal by performing a correlation operation between a received baseband signal and a reference spreading code in a spread spectrum communication system. The present invention relates to a correlator for spread spectrum communication that performs a correlation operation by rotating a phase.

[0002]

2. Description of the Related Art In a spread spectrum communication system used in radio communication such as a cellular phone, a transmitter modulates information data and then performs orthogonal spread modulation using a spread code sequence having a rate higher than that of the data modulation. Generates a transmission complex signal. Hereinafter, QPSK (Quadrature Phase Shift Keying) which is a modulation method of information data and spread codes used in a spread spectrum communication system.
The modulation will be described. A transmission complex signal Tx generated when orthogonal spread modulation is performed on the transmission side is represented by the following equation (1).

[0003]

(Equation 1)

In the equation (1), S is information data, Si is the in-phase component, Sq is a quadrature component, C is a spreading code sequence, Ci is an in-phase component, and Cq is a quadrature component. . Txi and Txq represent the in-phase component (I phase) signal and the quadrature component (Q phase) signal of the baseband signal after spread modulation output from the transmitter, respectively. The in-phase component and the quadrature component are in an orthogonal relationship. Therefore, each orthogonal component S
q and Cq are multiplied by an imaginary number j. Further, n added to each signal indicates a time sequence of the spread code sequence.

To extract transmission information data from a transmission complex signal on the receiver side, that is, to demodulate the reception data, a complex conjugate correlation operation is performed on the transmission complex signal and the same spreading code sequence used for spreading modulation. There is a need. Assuming that the transmission spreading code sequence and the complex conjugate code sequence are C ^* ,
The correlation operation Rx performed in the receiver is represented by the following equation (2).

[0006]

(Equation 2)

Therefore, when formula (2) is constituted by a logic circuit or the like, four systems of multiplication processing circuits and four systems of accumulation processing circuits are required. In the equation (2), T ₀ represents the minimum sampling unit (time) when performing correlation processing in the receiver, and the information data Si and Sq are code-spread at a rate N times the rate of the information data. Therefore, the number n of cumulative addition takes a value of n = 1 to N.

A sliding correlator has been conventionally used as a device for performing a correlation operation in a receiver. FIG.
FIG. 1 is a configuration block diagram of a conventional sliding correlator. The sliding correlator in FIG. 7 is a complex-type sliding correlator that can realize the correlation operation represented by Expression (2). In FIG. 7, Txi represents a received baseband signal in-phase component (I phase), and Txq represents a received baseband signal quadrature component (Q phase).
Same as xq. Also, Ci and Cq represent in-phase and quadrature component reference spreading codes, respectively.
i, the same as Cq.

In the sliding correlator shown in FIG. 7, the multiplication in equation (2) is performed by multipliers 71a to 71d, and the addition / subtraction is performed by adders 72a and 72b. The multiplication result of the reference spreading code and the received baseband signal is obtained. Is integrated by the number of samples and discharge (update) at each sample rate.
This is executed in the accumulators 73a and 73b. The accumulator 73a performs a convolution operation on the in-phase component and the accumulator 73b performs a convolution operation on the quadrature component, and outputs respective correlation outputs SC _i and SC _q .

A process of demodulating a received baseband signal in a conventional sliding correlator will be described. When the equation (1) is substituted into the equation (2), the equation (2) is expressed as the following equation (3).

[0011]

(Equation 3)

In the equation (3), Cii and Cqq are autocorrelation functions of the reference spreading codes of the in-phase component and the quadrature component, respectively, where Cii = Cqq = 1. Therefore, the relationship between each component output from the sliding correlator in FIG. 7 and the correlation output is expressed by the following equation (4).

[0013]

(Equation 4)

Therefore, it is apparent from the equation (4) that the received baseband signal is demodulated by executing the correlation operation in the conventional sliding correlator.

The above-described sliding correlator is used when the timing of the received baseband signal and the timing of the reference spreading code generated on the receiver side match. When it is necessary to detect the timing of the received baseband signal and the reference spreading code and correct the phase, a matched filter is used. The matched filter stores the received baseband signal and the reference spreading code in a time-series manner, and executes a correlation operation for each sample. The same arithmetic processing as that of the sliding correlator is executed for each sample.

FIG. 8 is a block diagram showing the configuration of a conventional matched filter. The matched filter in FIG. 8 is a complex type matched filter that executes the correlation operation represented by the equation (2) for each sample. In the matched filter of FIG. 8, the received baseband signal in-phase component Tx is sampled every sample.
i, and the received baseband signal quadrature component Txq are input to delay units 81a and 81b, respectively. Delay devices 81a and 81
“b” has a configuration in which n registers are connected in series. When data is input, the data stored so far is shifted to the next-stage register to update each register.

The in-phase component of the received baseband signal, the orthogonal component of the received baseband signal, and the reference spread code storage unit (not shown) for the in-phase component and the orthogonal component output from the delay units 81a and 81b for each sample. N reference spreading codes Ci (1) to Ci (n) for n in-phase and quadrature components,
Cq (1) to Cq (n) are used as multipliers 82a-1 to 82a-
n, 82b-1 to 82b-n, 82c-1 to 82c-
n, 82d-1 to 82d-n are respectively input and multiplied, and the result of the multiplication is input to adders 83a to 83d to perform an addition process. Adders 83a to 83d
Are further added to an adder 84a and a subtractor 84b.
The adder 84a outputs the correlation output MFi of the in-phase component, and the subtractor 84b outputs the correlation output MFq of the quadrature component. In the matched filter of FIG. 8, the correlation operation of equation (2) is performed for each sample by the operation described above. The output correlation outputs MFi and MFq of each component take the maximum value at the timing when the time series of the received baseband signal stored in the delay unit and the time sequence of the reference spreading code match, so that the peak path can be detected. .

[0018]

However, the conventional correlator for spread spectrum communication requires a large number of multipliers and adders in order to realize the correlation operation, so that the circuit scale is increased. there were. In particular, since the matched filter has a large number of multipliers and adders for the purpose of performing a correlation operation for each sample,
There is a problem that the circuit size is further increased, and since they operate at the sampling period, the power consumption is increased.

As a conventional example for solving such a problem,
JP-A-11-308149 published on November 5, 1999
No. "4-phase correlator" (applicant: Mitsubishi Electric Corporation, inventor: Kazuaki Ishioka et al.) Has been proposed. This conventional example switches the code of the in-phase component and the quadrature component of the received baseband signal based on the reference spreading code of the in-phase component and the quadrature component, that is, by providing signal selecting means for performing a phase rotation operation, Since the number of means and adding means can be reduced, a small and low power consumption correlator can be realized.

In the conventional correlator described above, FIG.
FIG. 1 shows a configuration diagram of a typical four-phase correlator. In this four-phase correlator, only a phase rotation of an in-phase component and a quadrature component of a received baseband signal is performed. The configuration 1 alone does not satisfy the above equation (4), and does not completely realize the correlation operation. Therefore, in order to realize the correlation operation, it is necessary to further supplement the logic circuit elements, but there is no disclosure in the prior art.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a correlator for spread spectrum communication capable of reducing a circuit scale, reducing power consumption, and completely implementing a correlation operation. I do.

[0022]

A correlator for spread spectrum communication according to the present invention for solving the above-mentioned problems of the prior art comprises a baseband signal of a four-phase modulated spread spectrum signal, a reference spread code, A correlator for spread spectrum communication that performs a correlation operation of: an adder that performs an addition process on a received baseband signal in-phase component and a received baseband signal quadrature component; and the reception baseband in-phase component signal and the reception baseband quadrature component. A subtractor for performing a subtraction process with a signal; an adder; and 0 for an output result of the subtractor.
A phase rotator that performs a demodulation process by applying any one of phase rotations of °, -90 °, -180 °, and -270 °, and outputs a demodulation result of an in-phase component and a quadrature component; and a demodulation result of the in-phase component. And an in-phase component adder that outputs the accumulated addition result as an in-phase component correlation output, and a quadrature component adder that adds the quadrature component demodulation results and outputs the accumulated addition result as a quadrature component correlation output. A phase rotator comprising: a first multiplier that multiplies the addition result output from the adder with a reference spreading code of an in-phase component; and a subtractor. A second multiplier for multiplying the output subtraction result by the orthogonal component reference spreading code; and a third multiplier for multiplying the in-phase component reference spreading code by the orthogonal component reference spreading code. Multiplied by the third multiplier An in-phase component data selector that selects one of the multiplication results of the first multiplier or the second multiplier based on the result and outputs the result as an in-phase component demodulation result; A quadrature component data selector that selects one of the multiplication results of the first multiplier or the second multiplier based on a result and outputs the result as a quadrature component demodulation result. The circuit scale can be reduced, the power consumption can be reduced, and the correlation operation of the received baseband signal can be completely realized.

A correlator for spread spectrum communication according to the present invention includes an adder for performing an adding process of a received baseband signal in-phase component and a received baseband signal quadrature component, and a receiving baseband in-phase component signal and a received baseband quadrature signal. A subtracter that performs a subtraction process with a component signal, an addition output delayer that stores and delays an output result of the adder and outputs an addition result stored at a different timing, and stores an output result of the subtractor. A subtraction output delayer that delays and outputs a subtraction result stored at a different timing; and an addition output delayer and an output result of the subtraction output delayer provided for each output result of the subtraction output delayer. 0 °, -90
°, -180 °, and -270 ° to apply any one of the phase rotations to perform demodulation processing, and output a plurality of phase rotators that output demodulation results of in-phase and quadrature components, and output from all phase rotators. The in-phase component adder that outputs the accumulated in-phase component demodulation results and outputs the accumulated addition result as a correlation output of the in-phase components, and the demodulation results of the quadrature components output from all the phase rotators are added and accumulated. A quadrature component adder that outputs an addition result as a quadrature component correlation output.The correlator for spread spectrum communication includes a phase rotator that outputs the addition result output from the addition output delay unit and a reference to the in-phase component. A first multiplier for performing multiplication with a spreading code, a second multiplier for performing multiplication of the subtraction result output from the subtraction output delay unit and a reference spreading code for orthogonal components, and a reference for in-phase component reference; Spreading code and orthogonal A third multiplier for performing multiplication with the reference spread codes, on the basis of the multiplication result of the third multiplier,
Based on the in-phase component data selection unit that selects one of the multiplication results of the first multiplier and the second multiplier and outputs the result as a demodulation result of the in-phase component, based on the multiplication result of the third multiplier, And a quadrature component data selector that selects one of the multipliers or the multiplication result of the second multiplier and outputs the result as a quadrature component demodulation result.
The circuit scale can be significantly reduced, power consumption can be reduced, and time-series correlation calculation of a received baseband signal can be completely realized.

[0024]

Embodiments of the present invention will be described with reference to the drawings. A correlator for spread spectrum communication according to an embodiment of the present invention includes an adder that adds an in-phase component and a quadrature component of a received baseband signal, and a subtractor that subtracts the in-phase component and the quadrature component of the received baseband signal. And a phase rotator that demodulates a received baseband signal by performing a phase rotation based on a value of a reference spreading code of an in-phase component and a quadrature component with respect to an output result of the adder and the subtractor, The phase rotator is a first multiplier that multiplies a received baseband signal by an in-phase component and a reference spreading code of the in-phase component, and a second multiplier that multiplies the received baseband signal by a quadrature component and the orthogonal component by a reference spreading code. 2 multiplier, a third multiplier for multiplying the in-phase component and the quadrature component by the reference spreading code, and a first multiplication result or a second multiplication result based on an output result of the third multiplier. Izu A phase rotator having an in-phase component data selector and a quadrature component data selector for outputting a signal, whereby the circuit scale can be reduced, power consumption can be reduced, and correlation calculation of a received baseband signal can be realized. Can be.

FIG. 4 shows an addition output delay unit according to the present invention.
, The subtraction output delay unit is the delay unit 42b in FIG. 4, and the in-phase component adder is the accumulator 23a in FIG.
The adder 45a in FIG. 4, the quadrature component adder in the accumulator 23b in FIG. 2, the adder 45b in FIG. 4, the first to third multipliers in the multipliers 31a to 31c in FIG. The data selector corresponds to the data selector 32a in FIG. 3, and the orthogonal component data selector corresponds to the data selector 32b in FIG.

In the description of the prior art, the transmission information data and the spreading code sequence are indicated by symbols in equation (1), but in four-phase modulation, the combinations of values that the spreading code sequences Ci and Cq can take are (Ci, Cq) = (+ 1, + 1), (-1, +
1), (-1, -1), and (+1, -1). For example, a spread code sequence (Ci, Cq) = (+ 1, +1)
In the case of (1), the expression (1) can be expressed as the following expression (5).

[0027]

(Equation 5)

Similarly, when describing the case of another spreading code sequence pattern, it can be expressed by the following equations (6) to (8).

[0029]

(Equation 6)

FIG. 1 is a diagram showing a positional relationship of a transmission complex signal on a plane (hereinafter referred to as an IQ plane) having spread codes of an in-phase component and a quadrature component on coordinate axes. In FIG. 1, assuming that the state of equation (5) is a point in the first quadrant on the IQ plane, the states of equations (5) to (8) correspond to points shown in each quadrant. That is, equation (5) is for data Si-Sq, Si + S generated from information symbols.
q is rotated by 0 °, and similarly, equation (6) is 90 °.
°, equation (7) is 180 °, and equation (8) is 270 °.

The spread modulation / demodulation using the spread code sequence is performed by performing rotation modulation on the IQ plane. In other words, the transmitter performs spread modulation, that is, the phase rotation processing of transmission information data on the IQ plane. The four-state signal represented by the equation (8) is transmitted. On the receiver side,
In accordance with the reference spreading code sequence, the correlator performs a phase rotation process that is reverse to the spread modulation at points indicating the equations (5) to (8) in the IQ plane, and then performs a necessary addition or subtraction process. To perform the demodulation of the transmission information data Si and Sq.

The process of demodulating transmission information data in the correlator according to the present invention will be specifically described. When multiplication of the expressions (5) to (8) by the complex conjugate spreading code C ^* = Ci−Cq is performed, the expressions are represented as (5) ′ to (8) ′ below.

[0033]

(Equation 7)

Therefore, in order to demodulate the information data Si and Sq as shown by the equations (5) ′ to (8) ′ to the equation (4), first, a rotation process that is reverse to the spread modulation is performed. That is, in the case of the expression (5) ′, the rotation by 0 °, that is, the real part input signal 2Si and the imaginary part input signal 2Sq may be output as they are. Similarly, in the case of the expression (6) ′, after rotating −90 °, that is, multiplying the real part input signal −2Sq by −1, the real part input signal and the imaginary part input signal are exchanged and output, and (7) In the case of the expression (8) ', the real part input signal -2Si and the imaginary part input signal -2Sq are respectively multiplied by 11, and then output. , Imaginary part input signal-2Si
Is multiplied by 1 and then the real part input signal and the imaginary part input signal are interchanged and output.

The output result of the above-described reverse rotation processing is subjected to cumulative addition processing by a cumulative adder in the case of a sliding correlator, and added by a real part and imaginary part adder in the case of a matched filter. Is output as a correlation calculation result, the correlation in each correlator is completed.

FIG. 2 is a block diagram showing the configuration of the sliding correlator according to the first embodiment of the present invention. FIG. 3 is a block diagram showing the configuration of the phase rotator 22 in the sliding correlator of FIG. Hereinafter, the configuration of the sliding correlator according to the first embodiment (hereinafter, referred to as Embodiment 1) of the present invention will be described with reference to FIGS. The sliding correlator according to the first embodiment of the present invention includes an adder 21a, a subtractor 21b, a phase rotator 22, and accumulators 23a and 23b. The phase rotator 22 includes multipliers 31a to 31c,
It is composed of data selectors 32a and 32b.

The adder 21 a adds the received baseband signal in-phase component and the received baseband signal quadrature component, and outputs the addition result to the phase rotator 22. Subtractor 21
b subtracts the received baseband signal in-phase component and the received baseband signal quadrature component, and outputs the subtraction result to the phase rotator 22. Incidentally, in the above conventional example, the adder 2
The configuration of the device corresponding to 1a and the subtractor 21b is not shown, which is a clear difference from the conventional example. The phase rotator 22 performs a phase rotation process on the output results of the adder 21a and the subtractor 21b based on the values of the reference spreading codes of the in-phase component and the quadrature component, and outputs the demodulation results of the in-phase component and the quadrature component. I do. The accumulators 23a and 23b accumulatively add the demodulation results of the in-phase component or the quadrature component, and output the accumulative addition result for one symbol of each component as a correlation output. The accumulator 23a outputs the correlation output of the in-phase component, and the accumulator 23b outputs the correlation output of the quadrature component.

The multiplier 31a multiplies the addition result of the adder 21a by the reference spreading code of the in-phase component, and outputs the output result to the data selectors 32a and 32b. Multiplier 3
1b multiplies the subtraction result of the subtractor 21b by the reference spreading code of the orthogonal component, and outputs the output result to the data selection unit 32a.
And 32b. The multiplier 31c multiplies the in-phase component and the quadrature component by a reference spreading code, and outputs an output result to the data selection units 32a and 32b. Based on the multiplication result of the multiplier 31c, the data selection units 32a and 32b select one of the multiplication results of the multiplier 31a or the multiplier 31b.
The accumulator 23 uses one of the multiplication results as a demodulation result.
a or 23b. The data selector 23a outputs the demodulated result of the in-phase component to the accumulator 23a, and the data selector 23b.
Outputs the orthogonal component demodulation result to the accumulator 23b.

Next, the operation of the sliding correlator according to the first embodiment of the present invention will be described with reference to FIGS. The received baseband signal in-phase component Txi and the received baseband signal quadrature component Txq are first output to the adder 21a and the subtractor 21b in the sliding correlator of FIG. When the received signal of each component is input, the adder 21a calculates Txi + Txq and the subtractor 21b calculates -Tx + Txq.
The calculation of xi + Txq is performed. This arithmetic processing multiplies the received signal by a complex conjugate spreading code, that is, (5) to
The conversion process from the expression (8) to the expressions (5) ′ to (8) ′ is performed. The real part in the expressions (5) ′ to (8) ′ is calculated by the adder 21a, and the imaginary part is calculated by the subtracter 21b. Is output. Hereinafter, the output result of the multiplier 21a is referred to as a real part of input received data, and the output result of the subtracter 21b is referred to as an imaginary part of input received data.

The real part of the input received data and the imaginary part of the input received data are input to the phase rotator 22 together with the in-phase component reference spreading code Ci and the orthogonal component reference spreading code Cq.
In FIG. 3, a multiplier 31a is provided with a reference spreading code Ci for the real part of the input received data and the in-phase component, and a multiplier 31b is provided with a reference spreading code Cq for the imaginary part of the input received data and the orthogonal component.
The multiplier 31c multiplies the reference spreading code Ci of the in-phase component by the reference spreading code Cq of the quadrature component. The multiplication results of the multipliers 31a to 31c are respectively output to the data selection unit 3
2a and 32b.

The data selectors 32a and 32b provide the multiplier 31a or the multiplier 32b based on the multiplication result of the multiplier 31C, that is, the multiplication result of the reference spreading code Ci of the in-phase component and the reference spreading code Cq of the orthogonal component. One of the output results is selected and output. Specifically, the data selection units 32a and 32b perform data selection when the multiplication result in the multiplier 31C is "1", that is, when the in-phase component reference spreading code Ci and the orthogonal component reference spreading code Cq are equal. The unit 32a outputs a real part of the input reception data, and the data selection unit 32b outputs an imaginary part of the input reception data. Multiplier 3
When the multiplication result in 1C is “−1”, that is, when the reference spreading code Ci for the in-phase component and the reference spreading code Cq for the orthogonal component are different, the data selection unit 32a outputs the imaginary part of the input received data and the data selection unit 32b. Outputs the input received data real part.

In the sliding correlator of FIG. 2, the data selectors 32a and 32b perform reverse rotation processing on the received signal. That is, the reference spreading code sequence Ci
0 °, -90 °, -180 °, based on the value of
Rotated by any one of -270 °,
Finally, a demodulation result represented by equation (4) can be obtained for each component. As a result of the reverse rotation processing on the received signal, the demodulation result of the in-phase component is output from the data selector 32a.
A demodulation result of the orthogonal component is output from the data selection unit 32b. In FIG. 3, the output result of the data selection unit 32a is a real part of the phase rotation output, and the output result of the data selection unit 32b is the imaginary part of the phase rotation output.

The demodulation results of the respective components output from the data selectors 32a and 32b are respectively added to the accumulators 23a and 23a.
b, and after accumulating and adding the number of samples, correlation outputs SCi and SCq of each component are output.

FIG. 4 is a block diagram showing a configuration of the matched filter according to the first embodiment of the present invention. Hereinafter, the configuration of the matched filter according to Embodiment 1 of the present invention will be described.
This will be described with reference to FIG. The matched filter according to Embodiment 1 of the present invention includes an adder 41a, a subtractor 41b,
Delay units 42a and 42b and reference spreading code storage unit 43
a, 43b, phase rotators 44-1 to 44-n, and adders 45a, 45b.

The adder 41a adds the received baseband signal in-phase component and the received baseband signal quadrature component, and outputs the addition result to the delay unit 42a. Subtractor 41b
Performs subtraction of the received baseband signal in-phase component and the received baseband signal quadrature component, and outputs the subtraction result to the delay unit 42b.
Output to Each of the delay units 42a and 42b includes n registers. When a new output result is input from the adder 41a or the subtractor 41b, each register shifts the data stored so far to the next-stage register. And outputs it to the phase rotators 44-1 to 44-n. The delay unit 42a can store an addition result of the adder 41a, and the delay unit 42b can store n subtraction results of the subtractor 41b. The reference spreading code storage units 43a and 43b accumulate the reference spreading codes of the in-phase component or the quadrature component and output to the phase rotators 44-1 to 44-n. The reference spreading code storage unit 43a stores the reference spreading code of the in-phase component, and the reference spreading code storage unit 43b stores the reference spreading code of the orthogonal component. The reference spreading codes that can be stored in the reference spreading code storage units 43a and 43b may be either one type or a plurality of types. The phase rotators 44-1 to 44-n perform a phase rotation process on the output results of the delay units 42a and 42b based on the values of the reference spreading codes of the in-phase component and the quadrature component. Outputs the demodulation result of the component. The configuration of the phase rotators 44-1 to 44-n is the same as that of the phase rotator 22 in the sliding correlator of the first embodiment. The adders 45a and 45b include phase rotators 44-1 to 4-4.
4-n, add the demodulation results of the in-phase component or the quadrature component output from 4-n, and output a correlation output at each sample timing. The adder 45a outputs the correlation output of the in-phase component to the adder 45a.
b outputs correlation outputs of orthogonal components.

Next, the operation of the matched filter according to Embodiment 1 of the present invention will be described with reference to FIG. In the matched filter according to the embodiment of the present invention, when the received baseband signal in-phase component Txi and the received baseband signal orthogonal component Txq are input, they are output to the adder 41a and the subtractor 41b. In the adder 41a and the subtractor 41b, similarly to the sliding correlator of the first embodiment of the present invention described above, the received signal is multiplied by a complex conjugate spreading code, and the adder 41a performs (5) ′. ~
The real part in the equation (8) ′ is a delay unit (real part) 42a.
In the subtractor 41b, the imaginary part is a delay unit (imaginary part) 42b.
Respectively. The reference spreading code Ci of the in-phase component and the reference spreading code Cq of the orthogonal component are stored in a reference spreading code storage unit (real part) 43a and a reference spreading code storage unit (imaginary part) 43b, respectively.

Each of the delay units 42a and 42b has n registers connected in series. When data is input, the data stored so far is shifted to the next-stage register to update each register. Is going. Delay device 4
2a and 42b, the in-phase component of the received baseband signal and the quadrature component of the received baseband signal for each sample, and n reference in-phase components and quadrature components output from the reference spreading code storage units 43a and 43b. The spreading code is input to each of the phase rotators 44-1 to 44-n, subjected to reverse rotation processing, and the demodulation result of each component is output.

The demodulation results output from the phase rotators 44-1 to 44-n are input to the adders 45a and 45b, where the demodulation result of the number of samples is added, and the adder 45a outputs the same phase. The component correlation output MFi is output from the adder 45b, and the orthogonal component correlation output MFq is output from the adder 45b.
In the matched filter of FIG. 4, by the operation described above,
The correlation operation of the equation (2) is executed for each sample. The output correlation outputs MFi and MFq of the respective components take the maximum value at the timing when the time series of the received signal stored in the delay unit and the time sequence of the reference spreading code match, so that the peak path can be detected.

In the matched filter of FIG. 4, the number of adders for adding the demodulation result for each sample can be reduced from four to two. Since this adder adds a plurality of input data, the circuit scale can be greatly reduced by reducing this adder. Further, since the power consumption is proportional to the circuit scale, if the circuit scale is reduced, the power consumption can be reduced.

According to the sliding correlator according to Embodiment 1 of the present invention, an adder for adding the in-phase component and the quadrature component of the received baseband signal and a subtractor for subtracting the in-phase component and the quadrature component of the received baseband signal are provided. A phase rotator that performs demodulation processing of a received baseband signal for each component by performing a phase rotation process in a direction opposite to the spread modulation on the output result of the adder and the subtractor, and The effect of being able to completely realize the correlation calculation of the received baseband signal compared with the correlator of the above-described conventional example by being constituted by the accumulator that performs the correlation output for each component by separately performing the cumulative addition. There is.

Further, according to the matched filter according to the first embodiment of the present invention, an adder that adds the in-phase component and the quadrature component of the received baseband signal and subtracts the in-phase component and the quadrature component of the received baseband signal. A subtractor, an adder output delayer that stores and delays the output result of the adder and outputs an addition result for each sample timing, and stores and delays an output result of the subtractor and outputs the subtraction result for each sample timing. A demodulation process of the received baseband signal is performed for each component by performing a phase rotation process to the output of the subtraction output delay device, the addition output delay device, and the subtraction output delay device in a direction reverse to the spread modulation. It is composed of a plurality of phase rotators and a cumulative adder that performs a cumulative output of the demodulation results output from all the phase rotators for each component to perform correlation output for each component for each sample. By the fact, the correlation calculation of the received baseband signal for each sampling timing can be fully realized, as compared with the conventional matched filter, drastically can reduce the circuit scale, and there is an effect that power consumption can be reduced.

The sliding correlator and the matched filter according to the first embodiment of the present invention exhibit the above-described effects even when all of them are configured to be executed by analog elements or partially by analog. .

Attention is again directed to equations (5) to (8) representing the transmission complex signal for each pattern of the spreading code sequence. Since equation (5) can be regarded as a state in which data generated from the information symbol is rotated by 0 °, equation (6) is obtained by rotating equation (5) by 90 ° and equation (7) based on equation (5). Rotates 180 °,
Equation (8) can be regarded as being in a state rotated by 270 °. Considering the demodulation processing of the transmission information data based on this fact, in equation (5), the received baseband signal is rotated by 0 °, and in equation (6), −90 ° is obtained.
Rotate, and in formula (7), rotate -180 °
In equation (8), after rotating by -270 ° and converting to a phase rotation signal, (phase rotation signal in-phase component + phase rotation signal quadrature component) is used as the demodulation result of the in-phase component, and (phase rotation signal in-phase component−phase) By using the rotation signal orthogonal component) as the demodulation result of the orthogonal component, the correlation operation of the transmission information data represented by the equation (4) can be performed.

FIG. 5 is a block diagram showing the configuration of a sliding correlator according to the second embodiment of the present invention. The configuration and operation of each element constituting the sliding correlator of FIG. 5 are the same as those of the sliding correlator of FIG. The sliding correlator in FIG. 5 includes an adder 51a and a subtractor 51.
2 is different from the sliding correlator in FIG. 2 in that b is provided at the output destination of the accumulators 53a and 53b.

The correlator according to the first embodiment of the present invention adds or subtracts the in-phase component of the received baseband signal and the quadrature component of the received baseband signal and outputs the result to the phase rotator. In the sliding correlator of the embodiment (hereinafter, referred to as Embodiment 2), both components of the received baseband signal are directly input to the phase rotator, and the phase rotation signal output from the phase rotator is accumulated by the accumulator. After performing the cumulative addition process, by adding or subtracting the processing result of the in-phase component and the processing result of the quadrature component to obtain a demodulation result,
Correlation calculation of transmission information data is enabled.

FIG. 6 is a block diagram showing a configuration of a matched filter according to the second embodiment of the present invention. The configuration and operation of each element constituting the matched filter of FIG. 6 are the same as those of the matched filter of FIG. The matched filter in FIG. 6 includes an adder 61a and a subtractor 61b,
5B differs from the matched filter of FIG. 4 in that the configuration is provided at the output destination of 5b. In the matched filter according to the second embodiment of the present invention, the in-phase component and the quadrature component obtained by adding the phase rotation signals output from the plurality of phase rotators are added, and the addition result is added or subtracted to obtain the demodulation result. By doing so, correlation calculation of transmission information data can be performed.

The sliding correlator and the matched filter according to the second embodiment of the present invention can also perform the demodulation operation of the received signal for the above-described reason, and have the same size as the sliding correlator and the matched filter of the first embodiment. Therefore, there is an effect that the correlation operation of the received baseband signal can be completely realized. Further, in the matched filter, the circuit scale can be reduced as compared with the related art, and since the power consumption is proportional to the circuit scale, there is an effect that the power consumption can be reduced. As in the case of the sliding correlator and the matched filter according to the first embodiment, the above-described effects can be obtained even in a case where all analog elements or a part of analog circuits are used.

[0058]

According to the correlator for spread spectrum communication of the present invention, an adder for adding a received baseband signal in-phase component and a received baseband signal quadrature component is provided. A subtractor for performing a subtraction process on the band orthogonal component signal; an adder; and 0 °, −90 °, −180 °, −
A phase rotator that outputs a demodulation result of the in-phase component and the quadrature component by adding any one of the phase rotations of 270 ° to perform a demodulation process, and integrates and discharges the demodulation result of the in-phase component to obtain a correlation output of the in-phase component And a quadrature component accumulator that integrates and discharges the demodulation result of the quadrature component and performs a correlation output of the quadrature component. A first multiplier for multiplying the component by the reference spreading code, a second multiplier for multiplying the subtraction result output from the subtractor by the reference spreading code for the orthogonal component, A third multiplier for multiplying the reference spreading code by the reference spreading code of the orthogonal component, and a first multiplier or a second multiplier based on a multiplication result of the third multiplier. Select one of the multiplication results and output it as the in-phase component demodulation result A quadrature component that selects one of the multiplication results of the first multiplier or the second multiplier based on the multiplication result of the in-phase component data selection unit and the third multiplier and outputs the result as a quadrature component demodulation result The use of the phase rotator including the data selection unit has the effects of reducing the circuit scale, reducing power consumption, and completely implementing the correlation operation.

Further, according to the correlator for spread spectrum communication of the present invention, an adder for performing an adding process of a received baseband signal in-phase component and a received baseband signal quadrature component;
A subtractor for performing a subtraction process between the received baseband in-phase component signal and the received baseband quadrature component signal, and an addition output delay unit for storing and delaying the output result of the adder and outputting the addition result stored at a different timing A subtraction output delayer that stores and delays the output result of the subtractor and outputs the subtraction result stored at a different timing, an addition output delayer, and a subtraction output delayer provided for each output result of the subtraction output delayer. 0 °,-with respect to the output result of the dexterous delayer and the subtractor delayer
A plurality of phase rotators that perform demodulation processing by applying any one of phase rotation of 90 °, −180 °, and −270 °, and output a demodulation result of an in-phase component and a quadrature component. The demodulation result of the output in-phase component is added,
Adds the in-phase component adder that outputs the accumulated addition result as the correlation output of the in-phase component, and the demodulation results of the quadrature components output from all the phase rotators, and outputs the accumulated addition result as the correlation output of the quadrature component. A correlator for spread spectrum communication including a quadrature component adder, and the phase rotator is:
A first multiplier for multiplying the addition result output from the addition output delayer with the reference spreading code of the in-phase component, a subtraction result output from the subtraction output delayer, and a reference spreading code for the orthogonal component , A third multiplier for multiplying the in-phase component reference spreading code and the orthogonal component reference spreading code, and a multiplication result of the third multiplier. The in-phase component data selection unit that selects one of the multiplication results of the first multiplier or the second multiplier and outputs the result as a demodulation result of the in-phase component, and a multiplication result of the third multiplier, A phase rotator having a quadrature component data selection unit that selects one of the multiplication results of the first multiplier or the second multiplier and outputs the result as a demodulation result of the quadrature component provides a large circuit scale. And reduce power consumption,
In addition, there is an effect that a time series correlation operation of the received baseband signal can be completely realized.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a positional relationship of a transmission complex signal on an IQ plane.

FIG. 2 is a configuration block diagram of a sliding correlator according to the first embodiment of the present invention.

FIG. 3 is a block diagram illustrating a configuration of a phase rotator in the sliding correlator of FIG. 2;

FIG. 4 is a configuration block diagram of a matched filter according to the first embodiment of the present invention.

FIG. 5 is a configuration block diagram of a sliding correlator according to a second embodiment of the present invention.

FIG. 6 is a configuration block diagram of a matched filter according to a second embodiment of the present invention.

FIG. 7 is a configuration block diagram of a conventional sliding correlator.

FIG. 8 is a configuration block diagram of a conventional matched filter.

[Explanation of symbols]

21a, 41a, 51a, 61a, 72a, 84a ... adders, 21b, 41b, 51b, 61b, 72b, 8
4b: subtractor 22, 44, 52, 64: phase rotator 23a, 23b, 53a, 53b, 73a, 73
b: cumulative adder, 31a, 31b, 31c, 71a, 71
b, 71c, 71d, 82a, 82b, 82c, 82d
... Multipliers, 32a, 32b ... Data selectors, 42
a, 42b, 62a, 62b, 81a, 81b ... delay unit, 43a, 43b, 63a, 63b ... reference spreading code storage unit, 45a, 45b, 65a, 65b, 83
a, 83b, 83c, 83d ... adders (matched filters)

Claims (2)

[Claims] 1. A spread spectrum communication correlator for performing a correlation operation between a received baseband signal of a four-phase modulated spread spectrum signal and a reference spreading code, comprising: a received baseband signal in-phase component and a received baseband signal quadrature component. An adder for performing an addition process on the reception baseband in-phase component signal and a reception baseband quadrature component signal; a subtracter for performing a subtraction process on the reception baseband in-phase component signal and the reception baseband quadrature component signal. , −
A phase rotator that performs demodulation processing by adding any one of 90 °, −180 °, and −270 ° to output a demodulation result of an in-phase component and a quadrature component, and adds the demodulation result of the in-phase component. And an in-phase component adder that outputs the accumulated addition result as a correlation output of the in-phase component, and a quadrature component adder that adds the demodulation result of the quadrature component and outputs the accumulated addition result as a correlation output of the quadrature component. A phase rotator, wherein the phase rotator multiplies an addition result output from the adder by a reference spreading code of an in-phase component, and the subtractor A second multiplier that multiplies the subtraction result output from the above with the orthogonal component reference spreading code, and multiplies the in-phase component reference spreading code and the orthogonal component reference spreading code. With a third multiplier An in-phase component data selection unit that selects one of the multiplication results of the first multiplier or the second multiplier based on a multiplication result of the third multiplier and outputs the result as a demodulation result of an in-phase component; A quadrature component data selection unit that selects one of the multiplication results of the first multiplier or the second multiplier based on the multiplication result of the third multiplier and outputs the result as a quadrature component demodulation result And a phase rotator comprising: 2. A spread spectrum communication correlator for performing a correlation operation between a received baseband signal of a four-phase modulated spread spectrum signal and a reference spreading code, comprising: a received baseband signal in-phase component and a received baseband signal quadrature component. An adder that performs an addition process with the subtractor; a subtractor that performs a subtraction process between the received baseband in-phase component signal and the received baseband quadrature component signal; An addition output delay unit that outputs the addition result stored in the subtraction unit; a subtraction output delay unit that stores and delays the output result of the subtractor and outputs a subtraction result stored at a different timing; And each of the output results of the subtraction output delay unit is 0 °, −90 °, -18 with respect to the output results of the adder delay unit and the subtractor delay unit. 0 °,
A plurality of phase rotators that perform demodulation processing by adding any one of -270 ° phase rotations and output demodulation results of in-phase and quadrature components; and the in-phase components output from all the phase rotators. And an in-phase component adder that outputs the accumulated addition result as a correlation output of the in-phase component, and adds the demodulation results of the quadrature components output from all the phase rotators, and accumulates the addition result. And a quadrature component adder that outputs a quadrature component correlation output, wherein the phase rotator is for adding the output result from the addition output delay unit and for referencing the in-phase component. A first multiplier that performs multiplication with a spreading code, a second multiplier that performs multiplication of the subtraction result output from the subtraction output delay unit and a reference spreading code of an orthogonal component, reference Multiplier for multiplying the spreading code for use with the reference spreading code for the orthogonal component, and the first multiplier or the second multiplication based on a multiplication result of the third multiplier. Component data selection unit that selects one of the multiplication results of the multiplier and outputs the result as a demodulation result of the in-phase component, and the first multiplier or the second multiplier based on the multiplication result of the third multiplier. A correlator comprising a quadrature component data selector for selecting one of multiplication results of the multiplier and outputting the result as a quadrature component demodulation result.