JP4793566B2 - Wireless communication apparatus and wireless communication method - Google Patents

Description

  The present invention relates to a technique for correcting signal characteristics of a radio signal in digital radio communication.

  In the digital wireless communication system, a spectrum mask is defined in order to prevent a wireless signal transmitted from a wireless device from affecting wireless communication between other stations. Each wireless device performs control so that the spectrum of the transmission signal satisfies this rule.

  By the way, the modulation circuit mounted on the wireless device is generally configured in consideration of the balance between cost and performance. Many of them have a configuration in which a modulated wave is generated by an analog quadrature modulator from a signal that has been subjected to digital / analog conversion through waveform shaping by digital processing and nonlinear distortion correction.

  In the above configuration, if the signal input to the analog quadrature modulator has an error due to, for example, a DC offset, carrier leak is caused in the transmission signal, and as a result, it becomes difficult to satisfy the spectrum mask. In addition to the DC offset described above, analog circuits have imperfections that lead to level errors and Ich / Qch orthogonal deviations, which cause communication quality to deteriorate.

  Conventionally, there has been a method of finely adjusting a variable resistor or the like provided in an analog unit manually as a countermeasure for deterioration in communication quality. However, it takes time to make adjustments, and it is difficult to cope with characteristic deterioration due to temperature changes and changes with time. Therefore, as one countermeasure, for example, a technique described in Patent Document 1 described below has been proposed. In this document, a quadrature demodulator, analog-to-digital converter, and DSP are added to the conventional modulation circuit, and a DC offset is tried so that it approaches the quadrature demodulator output when there is no input to the quadrature demodulator. A transmitter is described in which carrier leak is suppressed by changing.

On the other hand, a quasi-synchronous detection technique is generally used for a demodulation circuit of a wireless device. In a demodulation circuit using quasi-synchronous detection, the oscillation frequency of the LO (local oscillator) does not completely match the carrier frequency of the input signal. Therefore, the baseband signal after demodulation has a phase rotation corresponding to the frequency difference. The element remains. This element is removed using a carrier recovery circuit having a feedback loop configuration, but the removed baseband signal still has imperfections in the signal generated on the transmission side. As a technique for compensating for this inconvenience, for example, a technique described in Patent Document 2 described later has been proposed.
JP 2000-244596 A JP 2001-211220 A

  According to the technique described in Patent Document 1, it is possible to appropriately cope with temperature changes, power supply voltage fluctuations, and the like. However, the modulation circuit in the transmitter of the document requires a demodulation circuit that is not necessary for the original modulation function, which complicates the circuit and increases the cost accordingly.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a technique for easily correcting imperfections of a transmission signal caused by analog processing in a modulation circuit of a wireless communication apparatus.

A radio communication apparatus according to the present invention is a radio communication apparatus that communicates radio signals between its own station and an opposite station, and correction for correcting signal characteristics of the radio signal to be transmitted by the opposite station at the opposite station. calculated values, demodulating means for transmitting the correction value to the opposite station, and means for correcting by the correction value received signal characteristics of the radio signal to be transmitted to the opposite station from said opposite station, a radio signal from the opposite station A demodulation circuit for obtaining a correction value to be transmitted to the opposite station based on an error between a signal characteristic including a DC offset component of the baseband signal obtained by the demodulation and a prescribed signal characteristic, and a correction obtained by the demodulation circuit A data processing circuit that multiplexes the value with the transmission data of the auxiliary signal and extracts the correction value for correction at the local station from the baseband signal, and for correction of the multiplexed transmission data at the local station A modulation circuit that corrects with the correction value and modulates the transmission data, and the demodulation circuit includes an error correction unit that corrects an error between a signal characteristic of the baseband signal and a specified signal characteristic, and a plurality of carrier waves An absolute phase detection circuit that obtains an absolute phase corresponding to the opposite station from the phase, and a correction value that converts the error relating to signal characteristics into a value corresponding to the absolute phase and uses the value as the correction value to be multiplexed with transmission data characterized in that it comprises a converting circuit.

The radio communication method according to the present invention is a radio communication method for communicating a radio signal between the own station and the opposite station, wherein the transmission means sets the signal characteristics of the radio signal to be transmitted by the opposite station to the opposite station. Obtaining a correction value for correction, transmitting the correction value to the opposite station, and correcting the signal characteristic of the radio signal to be transmitted to the opposite station with the correction value received from the opposite station. And the demodulation circuit demodulates the radio signal from the opposite station, and the correction to be transmitted to the opposite station based on the error between the signal characteristic including the DC offset component of the baseband signal obtained by the demodulation and the specified signal characteristic. A demodulation step for obtaining a value, and a data processing circuit multiplexes the correction value obtained by the demodulation circuit with transmission data of an auxiliary signal, and extracts the correction value for correction at the own station from the baseband signal And a modulation circuit corrects the multiplexed transmission data with the correction value for correction at the local station, and modulates the transmission data. In the demodulation step, an error correction unit includes: A step of correcting an error between the signal characteristic of the baseband signal and a prescribed signal characteristic, an absolute phase detection circuit obtaining an absolute phase corresponding to the opposite station from a plurality of carrier wave phases, and a correction value conversion circuit Converting the error relating to the signal characteristics into a value corresponding to the absolute phase, and setting the value as the correction value to be multiplexed on the transmission data .

  According to the present invention, an analog value such as a DC offset component can be obtained without supplying any special hardware to the wireless communication device by supplying a correction value obtained by the local station with respect to the signal characteristics of the wireless signal to the opposite station. Processing incompleteness can be compensated for between the own station and the opposite station. Thereby, cost reduction and productivity improvement in the system can be realized, and it is possible to cope with a change with time and a temperature change in each wireless communication device.

  FIG. 1 shows a block diagram of an embodiment of the present invention. The illustrated wireless communication apparatus 100 and wireless communication apparatus 200 have the same configuration described later. Hereinafter, for convenience, radio communication apparatus 100 will be described as its own station, and the other radio communication apparatus 200 will be described as an opposite station.

  The receiver 6 of the radio communication device 100 receives the radio signal transmitted from the radio communication device 200 of the opposite station via the antenna 7, and generates a reception IF (intermediate frequency) signal. The demodulation circuit 4 demodulates the reception IF signal generated by the receiver 6 to generate an Ich (in-phase component) signal and a Qch (quadrature component) signal that are baseband signals. A correction value for correcting the signal characteristic is supplied to a TX DPU (data processing device for transmission) 1.

  The TX DPU 1 multiplexes the supplied correction value for the opposite station into an auxiliary signal, converts the auxiliary signal and the main signal into Ich / Qch signals as transmission data, and supplies them to the modulation circuit 3. The modulation circuit 3 generates a transmission IF signal from the supplied Ich / Qch signal and supplies it to the transmitter 5. The transmitter 5 converts the frequency of the supplied IF signal into an RF signal having a predetermined frequency, and transmits it to the radio communication apparatus 200 that is the opposite station through the antenna 7.

  In general, in a wireless communication system, not only a main signal but also an auxiliary signal such as monitoring information is transmitted and received between the own station and the opposite station. Since this auxiliary signal has a narrower band than the main signal, a large amount of data cannot be transmitted / received, but it is suitable for transmitting / receiving information having a relatively small data amount. In this embodiment, this is the reason why the correction value for the opposite station is multiplexed with the auxiliary signal.

  The radio communication device 200 of the opposite station supplies the RF signal from the radio communication device 100 received through the antenna 8 to the receiver 9. The receiver 9 converts the frequency of the RF signal into an IF signal and supplies it to the demodulation circuit 11. The demodulation circuit 11 supplies a baseband signal, which is reception data obtained by demodulating the IF signal, to an RX DPU (Reception Data Processing Device) 13.

  The RX DPU 13 takes out a correction value included in the received data and supplies it to the modulation circuit 12. This correction value is the above-described correction value multiplexed on the auxiliary signal by the radio communication apparatus 100. Based on the supplied correction value, the modulation circuit 12 corrects the transmission data to be transmitted to the radio communication apparatus 100, such as level error, orthogonal deviation, and DC offset deviation.

  Note that, since the configurations of the wireless communication device 100 and the wireless communication device 200 are the same as described above, the series of operations described above is performed even when the viewpoint of the station is changed, that is, the own station is set as the wireless communication device 200. The same applies to the case where the station is the wireless communication device 100, and a description thereof will be omitted.

  FIG. 2 shows the configuration of the demodulation circuit 4 (11). The demodulating circuit 4 shown in the figure has a configuration based on a baseband sampling type quasi-synchronous wave detection type demodulating circuit. Further, an equalizer or a circuit for compensating characteristics of the analog part of the demodulation circuit 4 may be added to the illustrated configuration.

  The demodulation circuit 4 is an error correction unit in the present invention, that is, a DC offset correction circuit 21, an orthogonal deviation correction, as a circuit for detecting and correcting an error between the signal characteristic of the radio signal from the opposite station and the specified signal characteristic. A circuit 22, a level correction circuit 23, and a control information generation circuit 24 are included. Further, the demodulation circuit 4 is handled by the correction value conversion circuit 25 that converts the correction values supplied from these correction circuits (21, 22, 23) into correction values for the opposite station, and the opposite station (200). And an absolute phase detection circuit for detecting an absolute phase corresponding to the carrier phase.

  In the demodulation circuit 4 shown in FIG. 2, the analog quadrature demodulator 15 converts the IF signal input from the receiver 6 into an Ich / Qch baseband signal using an output signal from the LO (local oscillator) 16. . Ich / Qch baseband signals are converted to digital signals via LPF (low-pass filter) 17a and 17b and A / D (analog-digital converter) 18a and 18b, and EPS (infinite phase shifter) It is input to 19. The EPS 19 removes the phase rotation element included in the supplied baseband signal, and then supplies it to the DC offset correction circuit 21.

  The DC offset correction circuit 21 corrects and corrects the DC offset component of the current baseband signal based on the control information fed back from the control information generation circuit 24 regarding the DC offset component of the baseband signal processed in the past. The baseband signal is supplied to the orthogonal deviation correction circuit 22. Further, the DC offset correction circuit 21 supplies an Ich / Qch correction value related to the DC offset component to the correction value conversion circuit 25.

  The orthogonal deviation correction circuit 22 corrects the orthogonal deviation between Ich / Qch in the baseband signal based on the control information from the control information generation circuit 24, and supplies the corrected baseband signal to the level correction circuit 23. Further, the Ich / Qch correction values related to the orthogonal deviation are supplied to the correction value conversion circuit 25. The level correction circuit 23 corrects the amplitude error of the baseband signal based on the control information from the control information generation circuit 24, and outputs the corrected baseband signal to the absolute phase detection circuit 26. Further, the Ich / Qch correction value related to the amplitude error is supplied to the correction value conversion circuit 25.

  The control information generation circuit 24 is used for correction processing in each correction circuit (21, 22, 23) based on Ich / Qch of the baseband signal that has undergone a series of correction processing regarding DC offset components, orthogonal deviation, and level error. Control values to be generated and fed back to each.

  The absolute phase detection circuit 26 detects the absolute phase corresponding to the opposite station and supplies the information to the correction value conversion circuit 25. The correction value conversion circuit 25 converts the various correction values supplied from the correction circuits (21, 22, 23) into values that can be used in the opposite station in accordance with the information from the absolute phase detection circuit 26, and converts them. Output to TX DPU1.

  The arrangement order of the DC offset correction circuit 21, the orthogonal deviation correction circuit 22, and the level correction circuit 23 is not limited to that shown in FIG. 2, and can be changed as appropriate. However, if a phase rotation element is included in the input baseband signal, that element is reflected in the correction value, so each correction circuit (21, 22, 23) removes the phase rotation element. Place it after the EPS19.

  FIG. 3 shows a configuration example of the DC offset correction circuit 21. The DC offset correction circuit 21 includes an averaging circuit 27a / 27b that generates a correction value by averaging control values supplied from the control information generation circuit 24 with respect to Ich / Qch of the baseband signal, and the generated correction value as EPS19. And an adder 28a / 28b for adding to the input signal from. The Ich / Qch correction value output from the averaging circuit 27a / 27b is added to Ich / Qch from the EPS 19, thereby correcting the DC offset component of the baseband signal. The Ich / Qch output from the adders 28a / 28b is a baseband signal with the DC offset component corrected, and is supplied to the orthogonal deviation correction circuit 22.

  FIG. 4 shows a configuration example of the orthogonal deviation correction circuit 22. This configuration example is based on the configuration proposed in the above-mentioned Patent Document 2 (Japanese Patent Laid-Open No. 2001-211220), but detects the Ich / Qch orthogonality and corrects the orthogonal deviation. As long as the configuration is obtained, the configuration is not limited to that illustrated.

  As shown in FIG. 4, the orthogonal deviation correction circuit 22 averages the control values from the control information generation circuit 24 related to the orthogonal deviation to generate a correction value, and the correction value and the DC offset correction circuit 21 Of the Qch input value, and an adder 30 that adds the multiplication result to the Ich input value from the DC offset correction circuit 21. The output of the averaging circuit 29 is supplied to the correction value conversion circuit 25 as a value for correcting the Ich / Qch orthogonal deviation.

  FIG. 5 shows a configuration example of the level correction circuit 23. The level correction circuit 23 averages the control values from the control information generation circuit 24 related to the amplitude error to generate correction values, and multiplies the Ich / Qch signal from the orthogonal deviation correction circuit 22 by the correction values. Multipliers 33a and 33b are configured. The correction value of the amplitude error is supplied to the correction value conversion circuit 25, and the Ich / Qch baseband signal is output to the control information generation circuit 24 and the absolute phase detection circuit 26.

  FIG. 6 shows a configuration example of the absolute phase detection circuit 26. The absolute phase detection circuit 26 applies phase rotation to the input Ich / Qch signals by phase rotators 34a, 34b, and 34c that give 90 °, 180 °, and 270 ° phase rotation, and data from the Ich / Qch signals of each phase. Demapping circuits 35a and 35b and 35c and 35d to be formed, frame synchronization circuits 36a and 36b and 36c and 37d for verifying the success or failure of frame synchronization for the data formed by demapping, and frame synchronization among the data of each phase And an absolute phase selection circuit 37 for specifying data established.

  FIG. 7 shows the configuration of the modulation circuit 3 (12). The Ich / Qch signal input from the TX DPU1 is band-limited by the waveform shaping filter 38 and then multiplied by the Ich / Qch level correction value for the own station supplied from the RX DPU2 in the multipliers 39a and 39b. The Further, after being added with the orthogonal correction value from the RX DPU2 by the adders 40a and 40b, the adder 42a and 42b add with the Ich / Qch offset correction value from the RX DPU2.

  Ich / Qch data corrected by various correction values is converted to analog signals by D / A (digital / analog converter) 43a and 43b, and then unnecessary high frequency components by LPF (low-pass filter) 44a and 44b Then, in the quadrature modulator 45, the signal is converted into an IF signal using the output of the LO 46 as a carrier wave and output to the transmitter 5.

  Next, the operation of this embodiment will be described. The radio wave transmitted from the antenna 8 of the radio communication device 200 serving as the opposite station is received by the antenna 7 of the own station (100), converted into an IF signal by the receiver 6, and input to the demodulation circuit 4.

  As described with reference to FIG. 2, the demodulation circuit 4 converts the input IF signal into a baseband Ich / Qch signal by the quadrature demodulator 15 and the LO 16. LPFs 17a and 17b remove unnecessary high frequency components from the Ich / Qch signal, and A / Ds 18a and 18b convert Ich / Qch into a digital signal.

  Here, the oscillation frequency of LO16 is almost the same as the oscillation frequency of LO46 (FIG. 7) in the modulation circuit 12 of the opposite station, but is not completely coincident, so the frequency of LO16 and LO46 is used as the baseband signal. The phase rotation corresponding to the difference remains. Therefore, the EPS 19 cancels the phase rotation by giving the baseband signal the phase rotation opposite to the remaining phase rotation according to the value supplied from the carrier reproduction circuit 20.

  Since the baseband signal from which phase rotation has been removed by EPS19 includes imperfections in analog processing in the modulation circuit 12 of the opposite station, these corrections are performed as follows. The correction target is a DC offset component, an orthogonal shift between Ich / Qch, and an amplitude error.

  The DC offset correction circuit 21 averages the Ich / Qch control information from the control information generation circuit 24 with respect to the Ich / Qch input signals output from the EPS 19, as described with reference to FIG. Is added. Control information relating to the DC offset component provided by the control information generation circuit 24 can be obtained by the following method.

  FIG. 8 shows the arrangement of QPSK signal points on the IQ complex plane according to the presence or absence of a DC offset. In the illustrated example, only the DC offset component is considered for convenience. The white point in the figure is the original signal point, that is, the signal point when the baseband signal does not contain a DC offset component, and the black point is the signal point when the DC offset component appears only on Ich (horizontal axis). It is. When the baseband signal includes a DC offset component, the four signal points form a square similar to the original signal point, but the position deviates from the original position as in the illustrated example.

  In the example of FIG. 8, it is assumed that the output value of Ich / Qch is expressed by a 2-bit two's complement. When there is no DC offset, “1” and “0” appear in the lower bits with a probability of 50%. On the other hand, when there is a DC offset, the lower bit has a higher probability of appearing “1” than “0”. Accordingly, the control information is obtained by inverting the lower bits and averaged, so that the DC offset correction value can be obtained.

  As described with reference to FIG. 4, the orthogonal deviation correction circuit 22 averages the control information from the control information generation circuit 24 to obtain a correction value, which is multiplied by the Qch input and then added to the Ich input.

  FIG. 9 shows the arrangement of QPSK signal points depending on the presence or absence of orthogonal deviation. The illustrated example is an arrangement that takes into account only orthogonal deviation. When there is an orthogonal shift, the shape formed by the four signal points changes from the original square to a parallelogram. The example of FIG. 9 is a case where a shift has occurred in the Ich (horizontal axis) direction. Therefore, orthogonal correction is performed by adding and subtracting the amplitude of the Ich signal to bring it closer to the original square. The baseband signal whose orthogonal deviation is corrected is supplied to the level correction circuit 23.

  As described with reference to FIG. 5, the level correction circuit 23 has a mechanism for multiplying the baseband signal Ich / Qch by the average of the control information from the control information generation circuit 24.

  FIG. 10 shows the arrangement of QPSK signal points depending on the presence or absence of level errors. The illustrated example is an arrangement that takes into account only level errors. If there is a level error, the four signal points extend from the original square to a rectangle. In order to correct the level error, the correction value is set using control information such that the signal point is “1” for the point inside the original point and “0” for the point outside the original point. May be generated and multiplied to the Ich / Qch signal. In the case of the illustrated example, the above operation can be realized by taking Ex-OR (exclusive OR) of 2-bit output and further inverting it.

  The baseband signal thus corrected is supplied to the absolute phase detection circuit 26. If the baseband signal includes all of the DC offset component, the quadrature shift, and the level error, the signal point is located at a position off the center as shown in FIG. It appears as a parallelogram that extends in either direction (horizontal axis).

  Here, in general, when quadrature modulation such as QPSK / QAM is used, since there are four types of phase uncertainty in the carrier phase reproduced in the demodulation circuit (4), Ich / Qch in the demodulation circuit (4) However, it does not necessarily correspond to Ich / Qch in the modulation circuit (12) on the transmission side. Therefore, there is a high probability that each correction value cannot be used as it is on the transmission side. Therefore, the absolute phase is detected by the absolute phase detection circuit 26 and the information is supplied to the correction value conversion circuit 25, thereby converting the correction value into a value that can be used on the transmission side.

  As shown in FIG. 6, the absolute phase detection circuit 26 applies phase rotation of 90 °, 180 °, and 270 ° to the input Ich / Qch signal by phase rotators 34a, 34b, and 34c, respectively. Together with the input signal itself, that is, Ich / Qch that is not subjected to phase rotation, a total of four types of signals having phases different by 90 ° are generated. The value of each signal by the phase rotation can be obtained by the following equation 1 where “I” and “Q” are before rotation and “I ′” and “Q ′” are after rotation.

[Equation 1]
0 ° rotation: I ′ = Q, Q ′ = I
90 ° rotation: I ′ = − Q, Q ′ = I
180 ° rotation: I ′ = − I, Q ′ = − Q
270 ° rotation: I ′ = Q, Q ′ = − I

  After obtaining the four types of phases as described above, they are input to the demapping circuits 35a and 35b and 35c and 35d, and data corresponding to the signal point represented by the Ich / Qch signal is output.

  Further, output data corresponding to each phase is input to the frame synchronization circuits 36a and 36b and 36c and 36d. Here, since any one of the four types of phases corresponds to the opposite station, only one piece of data can establish frame synchronization among the output data of the frame synchronization circuits (36a to 36d). The absolute phase selection circuit 37 identifies data that can properly establish frame synchronization, and detects the corresponding phase as an absolute phase. Information on the detected absolute phase is supplied to the correction value conversion circuit 25.

  The correction value conversion circuit 25 converts the correction value obtained from each correction circuit (21, 22, 23) into a value that can be used on the opposite station side based on the phase information from the absolute phase detection circuit. The DC offset correction value is converted by setting the pre-conversion Ich / Qch correction values to “Oi” and “Oq” and the post-conversion values to “Oi´” and “Oq´”. It is calculated | required by the formula shown in Formula 2.

[Equation 2]
0 ° rotation: Oi ′ = Oq, Oq ′ = Oi
90 ° rotation: Oi ′ = − Oq, Oq ′ = Oi
180 ° rotation: Oi ′ = − Oi, Oq ′ = − Oq
270 ° rotation: Oi ′ = Oq, Oq ′ = − Oi

  Further, in the correction value conversion circuit 25, the correction value of the orthogonal deviation is obtained as follows. FIG. 11 shows a rotated QPSK signal point arrangement when there is an orthogonal deviation. From FIG. 11, it can be seen that 0 ° and 180 °, 90 ° and 270 ° have the same arrangement. In the case of 0 ° and 180 °, correction is made by adjusting the amplitude of Ich (horizontal axis), and in the case of 90 ° and 270 °, the amplitude of Qch (vertical axis) is adjusted. Therefore, the circuit for orthogonal correction in the modulation circuit (3, 12) is configured to be able to adjust both Ich / Qch amplitudes.

  Here, regarding the orthogonal deviation, if the correction value before conversion is “α”, the Ich / Qch correction values “αi” and “αq” in each phase, and the correction values “I ′” and “Q” after conversion “′” Is obtained by the following equation (3).

[Equation 3]
For 0 ° and 180 °: αi = α and αq = 0, and I ′ = I + αi · Q and Q ′ = Q
For 90 ° and 270 °: αi = 0 and αq = α, and I ′ = I and Q ′ = Q + αq · I

  Further, regarding the level correction value, if the Ich / Qch correction values before conversion are “Gi” and “Gq”, the correction values “Gi ′” and “Gq ′” after conversion are expressed by the following equation (4). Desired.

[Equation 4]
In the case of 0 ° and 180 °: Gi ′ = Gi, Gq ′ = Gq
For 90 ° and 270 °: Gi ′ = Gi, Gq ′ = Gq

  Through the conversion process as described above, the correction value conversion circuit 25 converts the correction values from the correction circuits (21, 22, 23) into values applicable to the modulation circuit 12 of the opposite station, and converts them to the TX DPU1. Supply.

  The TX DPU 1 multiplexes the correction value for the opposite station with the auxiliary signal and uses it as transmission data. Further, the TX DPU 1 converts transmission data into Ich / Qch signals and supplies them to the modulation circuit 3. The modulation circuit 3 generates a transmission IF signal from the supplied Ich / Qch signal and supplies it to the transmitter 5. In the transmitter 5, the IF signal is frequency-converted to a predetermined radio frequency (RF) and transmitted to the opposite station through the antenna 7.

  The opposite station (200) demodulates the radio signal received from the antenna 9 into a baseband signal by the demodulation circuit 11 to form data, and the RX DPU 13 extracts various correction values multiplexed on the data. Then, the extracted correction value is supplied to the modulation circuit 12.

  The modulation circuit 12 has the configuration described with reference to FIG. The input Ich / Qch signal is band-limited by the waveform shaping filter 38, and further multiplied by the Ich / Qch level correction value supplied from the RX DPU 13 by the multipliers 39a and 39b, thereby correcting the level error. The

  Subsequently, in the adders 40a and 40b and the multipliers 41a and 41b, by calculating the orthogonal deviation correction value from the RX DPU 13 and the Ich / Qch signal in which the level error is corrected, Ich or Qch The quadrature correction is performed by changing the amplitude of. Further, after the DC offset correction is performed in the adders 42a and 42b, the signals are converted into analog signals by the D / A 43a and 43b. The LPFs 44 a and 44 b remove unnecessary high frequency components included in the analog signal and supply them to the quadrature modulator 45.

  The quadrature modulator 45 generates an IF signal by quadrature modulating the output of the LO 46. The IF signal generated in this way is in a state where the imperfections of the analog parts after D / A 43a and 43b are corrected. Transmitter 10 transmits an IF signal to radio communication apparatus 100 through antenna 8.

  According to the embodiment described above, in the digital radio apparatus using the quasi-synchronous detection type demodulation circuit (4, 11), by supplying the correction value obtained by the demodulation circuit of the own station to the opposite station, a special Without the need for additional hardware, incomplete analog processing such as a DC offset component can be compensated for between the own station and the opposite station. Further, since the correction value for the opposite station is multiplexed and supplied to the auxiliary signal, the correction value can be easily exchanged.

  Thereby, cost reduction and productivity improvement in the system can be realized, and it is possible to cope with a change with time and a temperature change in each wireless communication device.

  The demodulating circuits (4, 11) in the above embodiment are of the BB (baseband) sampling type as shown in FIG. 2, but in implementing the present invention, instead of this type, FIG. An IF sampling type demodulator circuit 4 ′ (11 ′) as shown may be used.

  As shown in FIG. 12, the demodulation circuit 4 ′ (11 ′) is configured to demodulate the IF signal input from the receiver (6, 9) after converting it to a digital signal. According to this configuration, it is difficult to realize high-speed processing as compared with the BB sampling type as shown in FIG. 2, but since the processing of the quadrature demodulator 51 is digital processing, there is an advantage that demodulation accuracy is improved. Therefore, what is necessary is just to select suitably the type of FIG. 2 or FIG. 12 according to the specification calculated | required by the radio | wireless communication apparatus (100, 200).

  In the above embodiment, quadrature modulation such as QPSK or QAM is applied as the modulation format. However, the scope of the present invention regarding the modulation format is not limited to quadrature modulation, and other types such as BPSK, for example. It may be a modulation format.

It is a block diagram which shows the structure of embodiment of the radio | wireless communication apparatus which concerns on this invention. It is a block diagram which shows the structure of the demodulation circuit in embodiment. It is a block diagram which shows the structure of the DC offset correction circuit in embodiment. It is a block diagram which shows the structure of the orthogonal deviation correction circuit in embodiment. It is a block diagram which shows the structure of the level correction circuit in embodiment. It is a block diagram which shows the structure of the absolute phase detection circuit in embodiment. It is a block diagram which shows the structure of the modulation circuit in embodiment. It is explanatory drawing regarding DC offset in embodiment. It is explanatory drawing regarding the orthogonal shift | offset | difference in embodiment. It is explanatory drawing regarding the level error in embodiment. It is explanatory drawing regarding the orthogonal deviation correction value in embodiment. It is a block diagram which shows the other structural example of the demodulation circuit in embodiment.

Explanation of symbols

100, 200 Wireless communication device 1, 14 TX DPU
2, 13 RX DPU
3, 12 Modulation circuit 4, 11 Demodulation circuit 5, 10 Transmitter 6, 9 Receiver 7, 8 Antenna 15: Analog quadrature demodulator, 16/46: LO (local oscillator), 17a / 17b / 44a / 44b: LPF (Low-pass filter), 18a / 18b: A / D (analog / digital converter), 19: EPS (infinite phase shifter), 20: carrier recovery circuit, 21: DC offset correction circuit, 22: orthogonal deviation correction Circuit: 23: Level correction circuit, 24: Control information generation circuit, 25: Correction value conversion circuit, 26: Absolute phase detection circuit 27a / 27b, 29, 32a / 32b Average circuit 28a / 28b, 30, 40a / 40b, 42a / 42b Adder 31, 33a / 33b, 39a / 39b, 41a / 41b Multiplier 34a / 34b / 34c / 34d Phase rotator 35a / 35b / 35c / 35d DEMAP ( Mapping circuit)
36a / 36b / 36c / 36d Frame synchronization circuit 37 Absolute phase selection circuit 38 Waveform forming filter 43a / 43b D / A (digital / analog circuit)
45 Quadrature modulator

Claims (7)

A wireless communication device for communicating a wireless signal between the own station and the opposite station,
It obtains a correction value for the opposite station corrects the signal characteristics of the radio signal to be transmitted in the opposite station, and means for transmitting the correction value to the opposite station,
Means for correcting a signal characteristic of a radio signal to be transmitted to the opposite station by a correction value received from the opposite station ;
A demodulation circuit for demodulating a radio signal from the opposite station and obtaining a correction value to be transmitted to the opposite station based on an error between a signal characteristic including a DC offset component of the baseband signal obtained by the demodulation and a prescribed signal characteristic; ,
A data processing circuit that multiplexes the correction value obtained by the demodulation circuit into transmission data of an auxiliary signal and extracts the correction value for correction at the local station from the baseband signal;
A modulation circuit that corrects the multiplexed transmission data with the correction value for correction at the local station and modulates the transmission data;
The demodulation circuit includes:
An error correction unit that corrects an error between the signal characteristic of the baseband signal and the specified signal characteristic;
An absolute phase detection circuit for obtaining an absolute phase corresponding to the opposite station from a plurality of carrier wave phases;
A correction value conversion circuit that converts the error relating to signal characteristics into a value corresponding to the absolute phase and sets the value as the correction value to be multiplexed with transmission data;
A wireless communication apparatus comprising: The absolute phase detection circuit, the baseband signal converts each signal obtained by matching a plurality of carrier phase on the received data, means for determining success or failure of frame synchronization to the received data, successful frame synchronization The wireless communication apparatus according to claim 1, further comprising means for selecting a carrier phase corresponding to received data as an absolute phase of the opposite station. The error correcting unit, a wireless communication apparatus according to claim 1 or 2, characterized in that it comprises a circuit for the DC offset component and the signal characteristics. The error correction section, and the angle between the orthogonal component and in-phase component of the baseband signal, any one of claims 1 to 3, characterized in that it comprises a circuit for amplitude and the signal characteristics of the baseband signal Item 1. A wireless communication device according to item 1. The demodulation circuit includes a demodulator that demodulates an intermediate frequency signal based on a radio signal from an opposite station to generate the baseband signal, and a converter that converts an output from the demodulator into a digital signal. the wireless communication apparatus according to any one of claims 1 to 4, characterized. The demodulation circuit includes a converter that converts an intermediate frequency signal based on a radio signal from an opposite station into a digital signal, and a demodulator that modulates an output from the converter to generate the baseband signal. the wireless communication apparatus according to any one of claims 1 to 4, characterized. A wireless communication method for communicating a wireless signal between a local station and an opposite station ,
A step of transmitting a correction value for correcting the signal characteristic of a radio signal to be transmitted by the opposite station at the opposite station, and transmitting the correction value to the opposite station;
A correcting unit correcting a signal characteristic of a radio signal to be transmitted to the opposite station by a correction value received from the opposite station;
A demodulation circuit demodulates a radio signal from the opposite station, and calculates a correction value to be transmitted to the opposite station based on an error between a signal characteristic including a DC offset component of the baseband signal obtained by the demodulation and a specified signal characteristic. The desired demodulation step;
A data processing circuit that multiplexes the correction value obtained by the demodulation circuit with transmission data of an auxiliary signal and extracts the correction value for correction at the local station from the baseband signal;
A modulation circuit comprising: correcting the multiplexed transmission data with the correction value for correction at a local station, and modulating the transmission data;
In the demodulation step,
An error correction unit correcting an error between a signal characteristic of the baseband signal and a specified signal characteristic;
An absolute phase detection circuit obtaining an absolute phase corresponding to the opposite station from a plurality of carrier wave phases;
A correction value conversion circuit converting the error relating to signal characteristics into a value corresponding to the absolute phase, and setting the value to the correction value to be multiplexed with transmission data;
Wireless communication method, which comprises a.

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