JP2007043608A - Amplitude/phase controller and receiving system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an amplitude/phase controller capable of speedily controlling an amplitude/phase even if a modulation scheme of an inputted signal is switched to different one. <P>SOLUTION: A multiplier 26 multiplies an inputted complex I/Q signal by a weight coefficient W calculated by a weight coefficient calculator 28 and outputs a result. A signal selector 34 selects and outputs either a hard determination signal Z or a reference signal V as a convergence target signal R. The convergence target signal R is inputted to an adder 30 via a polarity inverter 32. The adder 30 adds the signal outputted from the multiplier 26 and a polarity-inverted convergence target signal -R and inputs a result to the weight coefficient calculator 28. Furthermore, the inputted complex I/Q signal and a correction coefficient acquired by a correction coefficient reference section 42 are inputted to a multiplier 44. The weight coefficient calculator 28 executes an adaptation algorithm based on a corrected input signal Xp resulting from multiplying the inputted complex I/Q signal by the correction coefficient and an error signal (e) and calculates the weight coefficient W. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an apparatus for controlling and outputting at least one of amplitude and phase of an input complex signal.

  Digital modulation signals are widely used in digital wireless communications. The digital modulation signal is obtained by associating a symbol code with a digital code consisting of one bit or a plurality of bits as a unit with a physical quantity such as a phase of a carrier wave, a change amount thereof, and an amplitude at a predetermined time interval. Various digital modulation signal schemes are conceivable depending on the physical quantity of the carrier wave to which the symbol code is associated. For example, a PSK (Phase Shift Keying) modulation scheme in which the symbol code is associated with the phase of the carrier wave, and the symbol code is the carrier wave. There are QAM (Quadrature Amplitude Modulation) modulation schemes and the like associated with the amplitude and phase.

  The modulation component signal of the digital modulation signal is represented by a complex I / Q signal in which the real part is an in-phase component signal (hereinafter referred to as I signal) and the imaginary part is a quadrature component signal (hereinafter referred to as Q signal). Can do. Complex I / Q signals can be represented by complex vectors on the complex plane. Points represented by complex vectors in the complex plane are generally referred to as symbol points. The point represented by the complex vector of the complex I / Q signal changes discretely at a time interval in which the symbol code is associated with a physical quantity such as the phase of the carrier wave, its change amount, amplitude, etc., that is, the symbol period.

  The absolute value and the declination of the complex vector representing the complex I / Q signal are respectively associated with the amplitude and phase of the digital modulation signal. In this specification, the absolute value and declination of a complex vector representing a complex I / Q signal are referred to as the amplitude and phase of the complex I / Q signal, respectively, and these are collectively referred to as amplitude phase. Also, the absolute value of the complex vector representing the symbol point on the complex plane is referred to as the absolute value of the symbol point, and the declination of the complex vector representing the symbol point is referred to as the symbol point phase.

  FIG. 3 shows a configuration example of a complex I / Q signal used in digital wireless communication. The complex I / Q signal is obtained by arranging unit frames 22 in time series. The unit frame 22 includes a reference code frame 22a and an information code frame 22b. The receiving device receives and demodulates a unit frame 22 assigned in advance among a plurality of unit frames 22 connected in time series.

  The reference code frame 22a is a signal in which the reference code represented by the digital code string is associated with the amplitude or phase of the complex I / Q signal, and the information code frame 22b is a complex code of the information code represented by the digital code string. This is associated with the amplitude or phase of the I / Q signal. Here, the reference code is a code for the reception device to perform processing related to the reception operation, and the information code is a code including substantial information transmitted from the transmission device to the reception device, such as sound, an image, a program, and a database. It is.

  In the digital modulation signal, the accuracy of the device on the transmission side and the reception side is insufficient, the characteristics of the propagation path of the electromagnetic wave, the amplitude error, the phase error, etc. caused by the interference wave being superimposed on the reception wave, Or an error of a combination of these (hereinafter referred to as an amplitude phase error) is included. The amplitude phase error appears as an error of the absolute value of the symbol point of the complex I / Q signal or an error of the phase of the symbol point, which causes a decoding error of the digital code string. Therefore, the larger the amplitude / phase error contained in the digital modulation signal, the stronger the tendency of the error rate of the extracted digital signal to increase.

  The error rate is an index indicating the goodness of the reception state of the receiving apparatus. Further, reception performance such as reception sensitivity and interference wave resistance can be evaluated by an error rate. For example, it can be said that the reception sensitivity is better as the tendency of the error rate to increase when the received signal power decreases. Also, under the condition that a received signal with a certain power is received and an interference wave is received at the same time, the tolerance to the interference wave is better as the error rate tends to increase when the interference wave power increases. You can say that.

  FIG. 4 shows a configuration example of the receiving device 3 in the prior art. The receiving device 3 receives a digital modulation signal that is quadrature modulated by the I signal and the Q signal that form the complex I / Q signal of FIG.

  The receiving device 3 includes an antenna 10, a radio receiving unit 12, a quadrature detection unit 14, an A / D conversion unit 16, an amplitude / phase control unit 50, a code detection unit 20, and a timing synchronization unit 24. The receiving device 3 includes an amplitude phase control unit 50 that controls the amplitude phase of the complex I / Q signal in order to reduce the influence of the amplitude phase error included in the digital modulation signal and suppress the tendency of the error rate to increase. Yes. Thereby, the receiving performance of the receiving device 3 can be improved.

  The radio reception unit 12 performs high frequency amplification, frequency conversion to an intermediate frequency, and intermediate frequency amplification on the digital modulation signal received via the antenna 10 and inputs the result to the quadrature detection unit 14. The quadrature detection unit 14 extracts an I signal and a Q signal from the input digital modulation signal.

  The I signal and Q signal extracted by the quadrature detection unit 14 are input to the A / D conversion unit 16. The A / D converter 16 discretizes each of the I signal and the Q signal according to the symbol clock signal CK. Then, a complex I / Q signal is generated with the discretized I signal as a real part and the discretized Q signal as an imaginary part, and is input to the amplitude phase controller 50 and the timing synchronizer 24. In FIG. 4, j is an imaginary unit, and the complex I / Q signal is described as I + jQ.

  The timing synchronization unit 24 extracts a symbol period from the complex I / Q signal output from the A / D conversion unit 16 and generates a symbol clock signal CK synchronized therewith. The timing synchronization unit 24 inputs the generated symbol clock signal CK to the A / D conversion unit 16, the amplitude / phase control unit 50, and the code detection unit 20. Each of the A / D conversion unit 16, the amplitude phase control unit 50, and the code detection unit 20 operates at a timing according to the symbol clock signal CK.

  The timing synchronization unit 24 stores a waveform pattern of a complex I / Q signal corresponding to the reference code frame 22a. Then, the input of the reference code frame 22a is started by taking a waveform correlation between the complex I / Q signal output from the A / D converter 16 and the complex I / Q signal corresponding to the reference code frame 22a. Detect timing. When the timing synchronization unit 24 detects the timing at which the input of the reference code frame 22a is started, the weight coefficient calculation provided in the amplitude phase control unit 50 includes timing information T indicating the timing at which the input of the reference code frame 22a is started. Input to the unit 28.

  The amplitude phase control unit 50 controls the amplitude phase of the input complex I / Q signal and inputs the complex I / Q signal to the code detection unit 20. A complex I / Q signal as a series of unit frames 22 is input to the amplitude / phase control unit 50. The receiving device 3 demodulates only the unit frame 22 assigned in advance. Therefore, the amplitude phase control unit 50 newly controls the amplitude phase every time the assigned unit frame 22 is input.

  The amplitude / phase control unit 50 calculates an error signal representing a deviation of a symbol point indicated by a complex I / Q signal with respect to a reference symbol point defined in advance on a complex plane, and the complex I / Q signal is minimized so that the error signal is minimized. Amplitude phase control is performed.

  The amplitude phase control unit 50 includes a multiplication unit 26, a weight coefficient calculation unit 28, an addition unit 30, a polarity inversion unit 32, a signal selection unit 34, a hard decision unit 36, and a reference signal generation unit 40.

  The complex I / Q signal input to the amplitude / phase control unit 50 is input to the multiplication unit 26 and the weight coefficient calculation unit 28.

  The multiplier 26 multiplies the input complex I / Q signal by the weight coefficient W input from the weight coefficient calculator 28, and outputs this as the output signal Y of the amplitude phase controller 50. The output signal Y is input to the adding unit 30 and the hard decision unit 36. The weight coefficient W is a complex coefficient used for controlling the amplitude phase of the complex I / Q signal. The absolute value of the weight coefficient W represents the rate at which the amplitude of the complex I / Q signal is changed, and the declination angle represents the angle at which the phase of the complex I / Q signal is changed. Therefore, the multiplication unit 26 multiplies the complex I / Q signal by the weight coefficient W, whereby the amplitude phase of the complex I / Q signal can be changed according to the weight coefficient W.

  The hard decision unit 36 extracts the coordinate value of the symbol point from the output signal Y, performs a hard decision on the extracted coordinate value of the symbol point, and based on the hard decision, obtains the coordinate value of the symbol point to be originally taken. The hard decision signal Z corrected to a value is output. Here, the hard decision is a process of determining a coordinate value that should be originally taken based on a coordinate value of a determination target symbol point that is a symbol point to be determined. The determination is made by dividing the complex plane so that one section includes one reference symbol point which is a symbol point defined by the modulation method, and the determined symbol point found in one section is within the one section. Are located at the position of one reference symbol point defined within one section. For example, the to-be-determined symbol point A in FIG. 5 exists in a position not defined in the 16QAM modulation system in the section (1, -3). Therefore, in the hard decision, the to-be-determined symbol point A located in the section (1, -3) is considered to be located at the coordinate point 1-j3 of the reference symbol point of the section (1, -3).

  The reference signal generation unit 40 inputs the reference signal V to the signal selection unit 34. The amplitude and phase of the reference signal V change according to the reference code stored in the reference signal generation unit 40. This reference code is the same as the reference code included in the transmitted reference code frame 22a, and a common code determined in advance between the transmitting device and the receiving device 3 is applied.

  The signal selection unit 34 receives the hard decision signal Z and the reference signal V, and selects either the hard decision signal Z or the reference signal V according to the switching information S input from the weight coefficient calculation unit 28. , And output to the polarity inversion unit 32 as the convergence target signal R. The convergence target signal R is a signal that serves as a reference for the amplitude phase of the output signal Y. The polarity inversion unit 32 multiplies the convergence target signal R by −1 to invert the polarity and outputs the result to the addition unit 30.

  The adder 30 adds the output signal Y and the convergence target signal R whose polarity is inverted, and inputs the result to the weight coefficient calculator 28 as an error signal e. Since the polarity of the convergence target signal R is inverted in the polarity inversion unit 32, the error signal e is a signal obtained by subtracting the convergence target signal R from the output signal Y.

The weight coefficient calculation unit 28 executes an adaptation algorithm that converges the error signal e to the minimum value based on the error signal e and the complex I / Q signal input to the amplitude phase control unit 50. As a result, the amplitude phase of the output signal Y of the amplitude phase control unit 50 converges to the amplitude phase of the convergence target signal R. As an adaptation algorithm, an LMS algorithm, an RLS algorithm, or the like can be applied. The LMS algorithm can be expressed by a recurrence formula shown in the following formulas (1) to (3).
(Equation 1) Y (i) = X (i) · W (i) ^* (1)
(Equation 2) W (i + 1) = W (i) −μ · X (i) · e (i) ^* (2)
(Equation 3) e (i) = X (i) · W (i) ^{* −} R (i) (3)
Here, Y (i) is an output signal of the amplitude phase control unit 50, μ is an arbitrary constant for determining convergence and followability, X (i) is an input signal of the amplitude phase control unit 50, and W (i ) Is a weight coefficient, e (i) is an error signal, and R (i) is a convergence target signal. A variable marked with * in the upper right means that it is a complex conjugate variable of the variable, and i in parentheses of each variable is an integer representing a calculation step that increases with time.

  I representing the calculation step increases by 1 for each symbol period of the input complex I / Q signal. In this case, the LMS algorithm expressed by the equations (1) to (3) executes the unit calculation step of the algorithm every time the unit symbol period elapses. This also applies to other adaptive algorithms such as the RLS algorithm. That is, the step of executing the adaptation algorithm is synchronized with the timing at which the symbol point of the complex I / Q signal appears according to the symbol clock signal CK.

  The adaptation algorithm executed by the weight coefficient calculation unit 28 differs in the signal applied as the convergence target signal R when the reference code frame 22a is input and when the information code frame 22b is input. . While the reference code frame 22a is input, a pull-in process for executing the adaptation algorithm is performed using the reference signal V output from the reference signal generation unit 40 as the convergence target signal R. On the other hand, while the information code frame 22b is being input, the follow-up process is executed in which the adaptation algorithm is executed using the reference signal V output from the reference signal generation unit 40 as the convergence target signal R.

  The timing at which the state where the reference code frame 22a is input to the state where the information code frame 22b is input is detected based on the timing information T input from the timing synchronization unit 24 and the symbol clock signal CK. . The weight coefficient calculation unit 28 grasps the timing at which the input of the reference code frame 22a is started based on the timing information T. Then, the number of pulses of the symbol clock signal CK is counted from the time when the input of the reference code frame 22a is started, and when the number reaches the number of symbol points included in the reference code frame 22a, the signal selection unit 34. Is input to the signal selector 34 for switching the signal to be selected as the convergence target signal R. The signal selector 34 selects and outputs one of the two signals according to the switching information S.

  Thus, the pull-in process is performed while the reference code frame 22a is input, and the follow-up process is performed while the information code frame 22b is input for the following reason. From the viewpoint of simplifying the process of the amplitude / phase control unit 50, it is desired to only perform the tracking process. However, at the time immediately after the input of the unit frame 22 is started, that is, the time immediately after the head of the reference code frame 22a is received, the weight coefficient W for reducing the amplitude phase error is not yet determined. Therefore, even if the adaptation algorithm is executed using the hard decision signal Z for such a signal as the convergence target signal R, the possibility that the error signal e converges in a short time is low. Therefore, while the reference code frame 22a is being received, the weight coefficient W output from the weight coefficient calculation unit 28 is sufficiently converged to perform a process of drawing the amplitude phase of the output signal Y to an ideal value. Preferred.

  After the pull-in process, the follow-up process is performed because it is necessary to maintain the amplitude phase of the output signal Y at an ideal value. Since the information code included in the information code frame 22b is a code including substantial information transmitted from the transmission device to the reception device 3, the information code itself does not include information regarding the change pattern of the amplitude phase like the reference code. Absent. However, since the symbol point of the information code frame 22b has a regularity that ideally appears at a position determined by the modulation method, the tracking process uses this regularity. That is, as long as the error of the absolute value of the symbol point of the information code frame 22b and the error of the phase of the symbol point are within the range of one section on the complex plane, the signal output from the amplitude / phase control unit 50 The state in which the amplitude phase is drawn to an ideal value can be maintained.

  The code detector 20 extracts the coordinate value of the symbol point from the output signal Y, obtains a digital code string from the symbol code based on the extracted coordinate value of the symbol point, and outputs a digital signal in which this is arranged in time series Output.

  As described above, in the receiving device 3, the amplitude phase error included in the received digital modulation signal is reduced by the amplitude phase control unit 50. As a result, the error rate of the digital signal output from the code detector 20 can be reduced and the reception performance can be improved.

  The amplitude / phase control unit 50 of FIG. 4 has the following problem regarding the convergence of the adaptation algorithm.

  In many cases, the reference code frame 22a and the information code frame 22b of the digital modulation signal shown in FIG. That is, since the reference code is a code for the receiving apparatus to perform processing related to the receiving operation, it is desirable that a modulation scheme that facilitates processing related to the receiving operation is applied to the reference code, while the information code is used to transmit the transmitting apparatus. This is because it is desirable to apply a modulation scheme with a large amount of information to be transmitted per unit time to the information code.

  For example, consider a case where the PSK modulation scheme is applied to the reference code frame 22a and the QAM modulation scheme is applied to the information code frame 22b. Since the absolute value of the symbol point of the PSK modulation scheme is the same for all symbol points, the absolute value of the symbol point indicated by the complex I / Q signal is the adaptation algorithm when the reference code frame 22a is received. There is no variation for each execution step. However, since the absolute values of the symbol points of the QAM modulation scheme are not the same for all the symbol points, the absolute values of the symbol points indicated by the complex I / Q signal are adaptive when the information code frame 22b is received. Fluctuates for each execution step of the conversion algorithm. Therefore, when the reference code frame 22a is received and when the information code frame 22b is received, the time average value of the absolute value or power value of the symbol point indicated by the input complex I / Q signal is May be different. Here, the time average value of the absolute value of the symbol point refers to the time average value of the absolute value of the symbol point when the complex I / Q signal indicates all the symbol points at a uniform frequency, The time average value of the power value of the symbol point means a time average value of the power value of the symbol point when the complex I / Q signal indicates all the symbol points at a uniform frequency.

  The new weight coefficient W in the adaptation algorithm is calculated using the correction amount based on the input signal in the previous step. For example, in the LMS algorithm, the second term on the right side of equation (2) is the correction amount, which depends on the input signal X in the previous step. If the correction amount converges as the adaptation algorithm execution step increases, the output signal Y of the amplitude phase control unit 50 converges to a value in which the influence of the amplitude phase error is reduced. However, the convergence time of the amplitude phase error included in the output signal Y varies greatly depending on how the correction amount changes with an increase in the execution step. Therefore, the correction amount is preferably defined so as to give an optimum value for quickly converging the amplitude phase error included in the output signal Y.

  In the amplitude phase control unit 50 of FIG. 4, when the modulation scheme for the reference code frame 22a and the modulation scheme for the information code frame 22b are different, as described above, when the reference code frame 22a is received. In many cases, the absolute value of the symbol point or the time average value of the power value indicated by the complex I / Q signal differs from when the information code frame 22b is received. In a general adaptation algorithm, when the time average value is different, the time average value of the correction amount is also different. The correction amount itself shows a different value for each execution step, but the time average value of the correction amount is considered to indicate an effective value that affects the convergence of the adaptation algorithm.

  Accordingly, when switching from the reference code frame 22a to the information code frame 22b, there is a difference in the correction amount that there is a difference in the absolute value of symbol points or the time average value of the power value indicated by the complex I / Q signal. It is considered equal. If the equivalent distance of the correction amount at the time of switching from the reference code frame 22a to the information code frame 22b is too large, the absolute value of the error signal e increases rapidly at the beginning when the information code frame 22b is input, The convergence time in the subsequent follow-up process becomes long.

  Thus, when the convergence in the tracking process deteriorates, the tendency of the error rate of the digital signal output from the receiving apparatus 3 to increase increases, and the reception performance deteriorates. This problem becomes more prominent when the QAM modulation scheme is multi-valued to increase the communication capacity of the wireless communication system.

  The present invention has been made for such a problem, and an amplitude phase control device capable of quickly controlling an amplitude phase even when the modulation method of an input signal is switched to a different one. provide.

  The present invention relates to an amplitude phase control device that controls at least one of the amplitude or phase of an input complex signal to produce an output signal, the output signal with respect to a reference signal serving as a reference for at least one of amplitude and phase A difference signal generation unit that generates a difference signal representing a difference between the input signal, a correction input signal generation unit that generates a correction input signal obtained by correcting the input complex signal according to the modulation method of the input complex signal, And an amplitude phase changing unit that changes at least one of an amplitude and a phase of the input complex signal based on the difference signal and the modified input signal.

  In the amplitude phase control device according to the present invention, either the first complex signal that is a complex signal of the first modulation method or the second complex signal that is a complex signal of the second modulation method is input. When the second complex signal is input, the modified input signal generator generates an amplitude based on the time average value of the absolute value of the amplitude based on the information presentation value of the first complex signal and the information presentation value of the second complex signal. It is preferable that the modified input signal is generated by multiplying the input complex signal by a coefficient calculated from the ratio of the absolute value to the time average value.

  In the amplitude phase control device according to the present invention, either the first complex signal that is a complex signal of the first modulation method or the second complex signal that is a complex signal of the second modulation method is input. When the second complex signal is input, the modified input signal generator generates a time average value of power based on the information presentation value of the first complex signal and a time average of power based on the information presentation value of the second complex signal. It is preferable that the modified input signal is generated by multiplying the input complex signal by a coefficient calculated from the square root of the ratio to the value.

  A radio reception unit that receives the quadrature modulation signal; a quadrature detection unit that extracts an in-phase component signal and a quadrature component signal from the quadrature modulation signal received by the radio reception unit; the in-phase component signal and the quadrature component signal; In a receiving system comprising a complex signal generating unit that generates a complex signal from the digital signal and a digital demodulating unit that extracts a digital signal from the complex signal, the amplitude phase control device according to the present invention is applied to the digital demodulating unit Is preferred.

  ADVANTAGE OF THE INVENTION According to this invention, even when it switches to the thing from which the modulation system of the input signal differs, the amplitude phase control apparatus which can control an amplitude phase rapidly is realizable. Therefore, by applying the amplitude phase control apparatus according to the present invention to a receiving apparatus that receives signals of a plurality of different modulation schemes, it is possible to suppress an increase in the error rate of the output signal that occurs when the modulation scheme is switched. it can.

  FIG. 1 shows a configuration of a receiving apparatus 1 according to the embodiment of the present invention. The receiving apparatus 1 includes an antenna 10, a radio receiving unit 12, a quadrature detection unit 14, an A / D conversion unit 16, an amplitude / phase control unit 18, a code detection unit 20, and a timing synchronization unit 24. The same components as those of the receiving apparatus 3 in FIG.

  The radio reception unit 12 performs high frequency amplification, frequency conversion to an intermediate frequency, and intermediate frequency amplification on the digital modulation signal received via the antenna 10 and inputs the result to the quadrature detection unit 14. The quadrature detection unit 14 extracts an I signal and a Q signal from the signal input from the wireless reception unit 12 and inputs the signal to the A / D conversion unit 16. The A / D converter 16 generates a complex I / Q signal obtained by discretizing each of the input I signal and Q signal according to the symbol clock signal CK, and inputs the complex I / Q signal to the amplitude phase controller 18.

  The amplitude phase control unit 18 includes multiplication units 26 and 44, a weight coefficient calculation unit 28, an addition unit 30, a polarity inversion unit 32, a signal selection unit 34, a hard decision unit 36, a reference signal generation unit 40, and a correction coefficient reference unit 42. It is prepared for. The same components as those of the amplitude / phase control unit 50 of FIG.

  In the configuration of the amplitude phase control unit 18 in FIG. 1, a part different from the amplitude phase control unit 50 in FIG.

The correction coefficient reference unit 42 inputs a complex I / Q signal input to the amplitude phase control unit 18, that is, a correction coefficient corresponding to the modulation method of the input signal X, to the multiplication unit 44. Multiplying unit 44 is input to the weight coefficient calculation unit 28 as the corrected input signal X _p by multiplying the value input from the correction coefficient reference section 42 to the input signal X. Further, the switching information S is input from the weight coefficient calculation unit 28 not only to the signal selection unit 34 but also to the correction coefficient selection unit 42a.

  FIG. 2 shows the configuration of the correction coefficient reference unit 42. The correction coefficient reference unit 42 includes a correction coefficient selection unit 42a, a pull-in process correction coefficient generation unit 42b, and a follow-up process correction coefficient generation unit 42c.

  The switching information S output from the weight coefficient calculation unit 28 is input to the correction coefficient selection unit 42a. The correction coefficient selection unit 42a selects either the output value of the pull-in process correction coefficient generation unit 42b or the output value of the follow-up process correction coefficient generation unit 42c according to the switching information S, and inputs the selected value to the multiplication unit 44.

Thus, while the reference numeral frame 22a is input to the amplitude-phase control section 18, upon pull-in process at the time correction coefficient generator 42b pull-generated processed correction coefficient alpha ₁ is inputted to the multiplier 44, the information code frame While 22 b is being input to the amplitude phase control unit 18, the tracking process correction coefficient α ₂ generated by the tracking process correction coefficient generation unit 42 c is input to the multiplication unit 44.

Here, it is preferable to have the relationship of the following equation (4) between the correction coefficient α ₁ during the pull-in process and the correction coefficient α ₂ during the follow-up process.
(Expression 4) α ₂ / α ₁ = Hn / Hm (4)
Here, Hn is a time average value for the absolute value of the symbol point in the modulation scheme applied to the reference code frame 22a (a symbol when the complex I / Q signal indicates all symbol points at a uniform frequency). Hm is the time average value for the absolute value of the symbol point in the modulation scheme applied to the information code frame 22b. For example, if α ₁ = 1, α ₂ is determined as α ₂ = Hn / Hm. Further, the relationship between the correction coefficient α ₁ during the pull-in process and the correction coefficient α ₂ during the follow-up process can be expressed as the following expression (5) instead of the expression (4).
(Equation 5) α ₂ / α ₁ = (Pn / Pm) ^1/2 (5)
Here, Pn is the time average value of the power calculated from the symbol point in the modulation scheme applied to the reference code frame 22a, and Pm is the power calculated from the symbol point in the modulation scheme applied to the information code frame 22b. Is the time average value. Here, the power calculated from the symbol point is the frequency at which the complex I / Q signal uniformly distributes all the symbol points when the power of the symbol point is defined by using the absolute value of the symbol point as a voltage value or a current value. The time average value of the power calculated from the symbol points when

Pull-in process at the time correction coefficient generation unit 42b and the follow-up process time correction coefficient generating unit 42c is calculated in advance based on the respective ideal when pull-in process is previously calculated based on the symbol point correction coefficient alpha ₁ and an ideal symbol point It is preferable that the follow-up processing correction coefficient α ₂ is stored in advance.

In addition, a power measuring means (not shown) for measuring the time average value of the power calculated from the symbol points based on the input signal X is provided, and the correction coefficient α during the pull-in process is based on the result measured by the power measuring means. It is also possible to employ a configuration in which ₁ and the correction coefficient α ₂ at the time of the tracking process are calculated and input to the correction coefficient generation unit 42b and the correction coefficient at the time of the tracking process 42c, respectively.

Multiplying unit 44, the input signal X, and inputs the modified input signal X _p multiplied by the value input from the correction coefficient reference section 42 to the weight coefficient calculation unit 28.

Similar to the amplitude / phase control unit 50, the amplitude / phase control unit 18 according to the present embodiment performs pull-in processing when a complex I / Q signal for the reference code frame 22a is input, and performs a complex I / Q signal for the information code frame 22b. When is input, follow-up processing is performed. In the pull-in process, the signal selection unit 34 selects the reference signal V output from the reference signal generation unit 40 as the convergence target signal R, and in the tracking process, the hard determination signal Z output from the hard determination unit 36 is the convergence target signal R. Choose as. In the pull-in process, the correction coefficient reference unit 42 inputs the correction coefficient α ₁ during the pull-in process to the multiplication unit 44, and in the tracking process, the correction coefficient reference unit 42 multiplies the correction coefficient α ₂ during the tracking process by the multiplication unit 44. To enter.

The weight coefficient calculation unit 28 executes an adaptation algorithm based on the corrected input signal _Xp and the error signal e. For example, the LMS algorithm is expressed by a recurrence formula shown in the following formulas (6) to (10).
(Expression 6) Y (i) = X (i) · W (i) ^* (6)
(Expression 7) W (i + 1) = X (i) −μX _p (i) · e (i) ^* (7)
(Equation 8) e (i) = X (i) · W (i) ^{* −} R (i) (8)
(Equation 9) X _p (i) = α · X (i) (9)
(Equation 10) α = α ₁ (when a reference code frame is input), α ₂ (when an information code frame is input) (10) where Y (i) is an output signal of the amplitude / phase control unit 18, μ is a convergence property, An arbitrary constant for determining the followability, X (i) is an input signal of the amplitude / phase control unit 18, W (i) is a weight coefficient, e (i) is an error signal, R (i) is a convergence target signal, X _p (i) is a corrected input signal. A variable marked with * in the upper right means that it is a complex conjugate variable of the variable, and i in parentheses of each variable is an integer representing a calculation step that increases with time.

  Next, the principle of improving the convergence of the amplitude / phase control unit 18 according to the present embodiment will be described.

  When receiving a digital modulation signal having a different modulation scheme between the reference code frame 22a and the information code frame 22b, the receiving apparatus 1 according to the present embodiment receives an input when the reference code frame 22a is switched to the information code frame 22b. There may be a gap in the absolute value of the symbol point indicated by the complex I / Q signal or the time average value of the power value. This gap is considered to be equivalent to the gap of the correction amount with respect to the weight coefficient W in the adaptation algorithm.

  If the equivalent distance of the correction amount is too large, the convergence time of the amplitude phase error included in the output signal Y is prolonged. Therefore, when the complex I / Q signal of the modulation method applied to the information code frame 22b is input, if the correction amount of the weight coefficient W is corrected by the distance, it is included in the output signal Y. It can be said that it is possible to shorten the convergence time of the amplitude phase error. The equivalent distance of the correction amount is represented by the ratio of the time average value of the absolute value of the symbol point indicated by the signal of the information code frame 22b to the time average value of the absolute value of the symbol point indicated by the signal of the reference code frame 22a. The Alternatively, it is represented by the square root of the ratio of the time average value of power calculated from the symbol point indicated by the signal of the information code frame 22b to the time average value of power calculated from the symbol point indicated by the signal of the reference code frame 22a. Therefore, after switching from the reference code frame 22a to the information code frame 22b, the difference in the correction amount can be reduced by multiplying the input signal X by the reciprocal of this ratio.

Based on such a principle, the amplitude and phase control unit 18 according to the present embodiment calculates the power calculated from the time average value of the absolute value of the symbol point of the complex I / Q signal or the symbol point of the complex I / Q signal. is intended to apply the modified input signal X _p obtained by correcting the magnitude of the input signal X to be inversely proportional to the square root of the time average value in the calculation of the weight coefficients W.

  The amplitude / phase control unit 18 corrects the input signal X based on the expression (4) or (5) when the reference code frame 22a is input and when the information code frame 22b is input. The coefficients are different for each frame. As a result, the equivalent distance of the correction amount of the weight coefficient W when switching from the reference code frame 22a to the information code frame 22b can be reduced, and the amplitude phase error included in the output signal Y can be quickly detected in the follow-up process. Can be converged to.

  As described above, the amplitude phase control unit 18 controls the amplitude phase of the complex I / Q signal and inputs the complex I / Q signal to the code detection unit 20. The code detector 20 extracts the coordinate value of the symbol point from the input complex I / Q signal, obtains a digital code string from the symbol code based on the extracted coordinate value of the symbol point, and arranges this in time series Output the digital signal.

  Here, the configuration and operation of the amplitude phase control unit 18 have been described on the assumption that the same modulation scheme is applied within the information code frame 22b. However, the amplitude / phase control unit 18 according to the embodiment of the present invention is applied not only when the same modulation scheme is applied within the information code frame 22b but also when the modulation scheme is switched within the information code frame 22b. Is possible. In this case, for each of a plurality of modulation schemes applied in the information code frame 22b, a correction coefficient having the same definition as the equation (4) or (5) is calculated, and the modulation scheme is calculated in the information code frame 22b. What is necessary is just to make it the structure which selects the correction coefficient according to a modulation system, whenever it switches.

  In the receiving apparatus 1 according to the present embodiment, the convergence of the amplitude / phase control unit 18 can be improved, so that the tendency of an increase in the error rate of the digital signal output from the receiving apparatus 1 is suppressed, and the receiving performance is improved. Can be made.

It is a figure which shows the structure of the receiver which concerns on embodiment of this invention. It is a figure which shows the structure of a correction coefficient reference part. It is a figure which shows the structure of the digital modulation signal which a receiver receives. It is a figure which shows the structure of the receiver by a prior art. It is a figure explaining a hard decision.

Explanation of symbols

  1, 3 receiver, 10 antenna, 12 wireless receiver, 14 quadrature detector, 16 A / D converter, 18, 50 amplitude phase controller, 20 code detector, 22 unit frame, 22a reference code frame, 22b information Code frame, 24 timing synchronization unit, 26, 44 multiplication unit, 28 weight coefficient calculation unit, 30 addition unit, 32 polarity inversion unit, 34 signal selection unit, 36 hard decision unit, 40 reference signal generation unit, 42 correction coefficient reference unit , 42a correction coefficient selection unit, 42b correction coefficient generation unit during pull-in processing, 42c correction coefficient generation unit during tracking processing.

Claims (4)

An amplitude and phase control device that controls at least one of the amplitude and phase of an input complex signal to generate an output signal,
A difference signal generation unit that generates a difference signal representing a difference of the output signal with respect to a reference signal serving as a reference of at least one of amplitude and phase;
A modified input signal generation unit that generates a modified input signal by modifying the input complex signal according to the modulation method of the input complex signal;
An amplitude phase changing unit that changes at least one of an amplitude and a phase of an input complex signal based on the difference signal and the corrected input signal;
An amplitude phase control apparatus comprising: The amplitude / phase control apparatus according to claim 1,
Either a first complex signal that is a complex signal of the first modulation scheme or a second complex signal that is a complex signal of the second modulation scheme is input,
When the second complex signal is input,
The modified input signal generator is calculated from a ratio between a time average value of the absolute value of the amplitude based on the information presentation value of the first complex signal and a time average value of the absolute value of the amplitude based on the information presentation value of the second complex signal. An amplitude / phase control apparatus characterized in that the modified input signal is generated by multiplying the inputted complex signal by the coefficient obtained. The amplitude / phase control apparatus according to claim 1,
Either a first complex signal that is a complex signal of the first modulation scheme or a second complex signal that is a complex signal of the second modulation scheme is input,
When the second complex signal is input,
The modified input signal generation unit calculates a coefficient calculated from the square root of the ratio between the time average value of power based on the information presentation value of the first complex signal and the time average value of power based on the information presentation value of the second complex signal. An amplitude / phase control apparatus, wherein the corrected input signal is generated by multiplying the input complex signal. A radio receiver for receiving the quadrature modulation signal;
A quadrature detection unit that extracts an in-phase component signal and a quadrature component signal from the quadrature modulation signal received by the wireless reception unit;
A complex signal generator for generating a complex signal from the in-phase component signal and the quadrature component signal;
A digital demodulator for extracting a digital signal from the complex signal;
A receiving system comprising:
4. The reception system comprising: the digital demodulating unit comprising the amplitude phase control device according to claim 1, which controls at least one of an amplitude and a phase of the complex signal. 5.

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