JP3300185B2 - Radio and how to use the radio - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention calculates a correction value by comparing a transmission input signal with a demodulation transmission output signal, distorts a modulation signal in advance with the correction value, and transmits the distorted modulation signal to a transmission amplifier. The present invention relates to an improvement of a radio device of a predistorter system which corrects output distortion generated in a transmission amplifier by inputting.

[0002]

2. Description of the Related Art In general, when a linear modulation system such as QPSK or multi-level QAM is used as a digitizing radio for mobile communication, deterioration of the reception error rate or transmission due to non-linear distortion generated in a transmission amplifier is caused. Since interference to adjacent channels occurs due to the spread of the spectrum, it is necessary to perform linearization correction on the transmission amplifier. As one method of this linearization correction, conventionally, a radio device has a so-called predistorter in which a modulation signal input to a transmission amplifier is distorted in advance to cancel nonlinear distortion generated in the transmission amplifier. The method is often used. In this correction method, a receiving circuit and a demodulating circuit are provided in a transmitting unit of a wireless device, or a part of the receiving unit is used to detect a part of an output of a transmission amplifier, and then demodulated and compared with an input signal. A method is known in which a distortion correction amount is obtained from the comparison value and corrected, and control is performed so that the difference from the demodulated value is always eliminated.

FIG. 2 shows a part of a conventional radio, and FIG. 4 shows an example of a transmission waveform. The operation of the conventional radio will be described. As shown in FIG. 4, at the timing of the transmission slots 41, 42,... Shown in FIG. 4A, the transmission waveform is obtained by converting the modulated wave of the preamble signal 43 and the transmission data 44 as shown in FIG. Is to be sent. (The transmission waveform in FIG. 4B is an enlarged view of the transmission waveform transmitted at one transmission slot timing shown in FIG. 4A.) As shown in FIG. The transmission input signal applied to the input terminal 1 is output to the D / A converter 3 via the multiplier 2. The transmission input signal input to the D / A converter 3 is converted into an analog signal by the D / A converter 3,
Output to modulator 4. The modulator 4 modulates a high-frequency signal separately input to the modulator 4 with the input analog transmission signal as a modulation signal, and outputs the modulation signal to the transmission amplifier 5. The modulated signal input to the transmission amplifier 5 is amplified to a required power by the transmission amplifier 5 to become a transmission output signal, output to the antenna 7 via the duplexer 6, and transmitted from the antenna 7.

At this time, a part of the transmission output signal passes through the attenuator 8 forming the feedback circuit, is selected by the switch circuit 20, and is input to the demodulator 10 of the receiving unit. The transmission output signal input to demodulator 10 is demodulated by demodulator 10 to become a demodulated transmission output signal, which is output to A / D converter 11. The demodulated transmission output signal input to the A / D converter 11 is converted into a digital signal and output to the distortion correction value operation storage unit 19.
The distortion correction value operation storage unit 19 includes a preamble signal reception memory 18, a distortion correction value operation circuit 12, a delay detection circuit 16, a variable delay unit 15, a distortion correction value storage memory 13, and a memory address calculation circuit 14. The demodulated transmission output signal input to the distortion correction value operation storage unit 19 is first converted into a preamble signal, which is output in the preamble signal reception memory 18 before the input demodulated transmission output signal shown in FIG. , And is stored as a signal demodulated through the transmission amplifier 5. Next, the demodulated preamble signal output from the preamble signal receiving memory 18 and the input preamble signal of the transmission input signal are converted into a distortion correction value calculation circuit 1.
2 and a comparison operation is performed by a distortion correction value calculation circuit 12 to calculate a distortion correction value by the transmission amplifier 5.

However, since there is a delay difference between the two preamble signals, before being input to the distortion correction value calculation circuit 12, the output of the preamble signal reception memory 18 and the transmission input signal are used to determine the delay detection circuit 16 , The delay amount of the demodulated preamble signal is detected, the transmission input signal is delayed by the variable delay unit 15 by the detected delay amount, and the phases of the demodulated preamble signal and the input preamble signal are matched.
The distortion correction value calculation circuit 12 obtains a correction value corresponding to the amplitude value of the input signal and outputs the correction value to the distortion correction value storage memory 13.
The distortion correction value is stored in the distortion correction value storage memory 13 based on the address from the memory address calculation circuit 14 corresponding to the amplitude value of the transmission input signal. With the next transmission input signal, a distortion correction value corresponding to the amplitude value of the transmission input signal is output from the distortion correction value storage memory 13 constituting the distortion correction value calculation storage unit 19, and the transmission input signal is corrected by the multiplier 2. The transmission output signal output from the transmission amplifier 5 is corrected so that there is no distortion.

[0006]

In a conventional radio, distortion is corrected by using only a preamble signal transmitted for a very short time to correct distortion generated in a transmission amplifier. Since there is data only at the sampling point, distortion correction values for all input levels cannot be obtained in the calculation of distortion correction values, and it is necessary to obtain distortion correction values by interpolation or the like. There is a problem that the standard such as channel leakage power may not be satisfied. In order to solve the above problem, the present invention provides a feedback circuit for attenuating a transmission output signal of a transmission amplifier by an attenuator and providing a feedback circuit, and a switching circuit is provided on each of an input side and an output side. Each time, the distortion correction value of the transmission amplifier is calculated using the test signal at the time of the empty slot between each transmission slot, and the distortion generated at the output of the transmission amplifier is calculated using the distortion correction value by the test signal. It is an object of the present invention to provide a wireless device and a method of using the wireless device, which are adapted to correct the following.

[0007]

In order to achieve the above object, a radio device of the present invention comprises at least a transmission amplifier for amplifying a modulation signal modulated by a transmission input signal, and a transmission output signal of the transmission amplifier. A feedback circuit having an attenuator to be fed back, and a distortion correction value calculation for calculating and storing a distortion correction value by comparing the transmission input signal with a demodulated transmission output signal obtained by demodulating the transmission output signal fed back by the feedback circuit. Comprising a storage unit, the distortion correction value read from the distortion correction value calculation storage unit, the transmission input signal is distorted according to the amplitude value of the transmission input signal, the output distortion of the transmission amplifier was corrected In a wireless device configured to output the transmission output signal to an antenna, a switch circuit for switching and connecting the output of the transmission amplifier to the feedback circuit having the attenuator or the antenna. And a switch circuit for switching and connecting the transmission output signal from the feedback circuit having the attenuator or the reception input signal from the antenna to a demodulation circuit, wherein each of the switch circuits transmits each of the transmission input signals. It switches to the feedback circuit side every time the slot ends.

More specifically, the distortion correction value calculation and storage unit of the wireless device according to the present invention comprises: a memory address calculation circuit for calculating an address from a transmission input signal in accordance with an amplitude value; A distortion correction value storage memory that reads a correction value, a variable delay device that delays the transmission input signal and outputs the delayed transmission input signal, and compares the delayed transmission input signal with the demodulated transmission output signal. A delay detection circuit that detects a delay amount of the demodulated transmission output signal and outputs the same to the variable delay device; and compares and calculates the delayed transmission input signal from the variable delay device with the demodulated transmission output signal to calculate the distortion. A distortion correction value calculation circuit for outputting a correction value to the distortion correction value storage memory. Also, the method of using the wireless device of the present invention is such that each switch circuit is switched to a feedback circuit at the end of each transmission slot of a transmission input signal, and a test signal is provided between the transmission slot of the transmission input signal and the transmission slot. A slot is provided, a test signal is input as a transmission input signal for each test signal slot, the test signal is fed back, demodulated, and used as a demodulation transmission input signal to be compared in a distortion correction value calculation storage unit. This is to correct the generated output distortion.

[0009]

According to the present invention, there is provided a radio device comprising at least a transmission amplifier for amplifying a modulated signal modulated by a transmission input signal, a feedback circuit having an attenuator for feeding back a transmission output signal of the transmission amplifier, and the feedback circuit. A distortion correction value calculation storage unit that calculates and stores a distortion correction value by comparing a demodulated transmission output signal obtained by demodulating the transmission output signal and the transmission input signal, the distortion correction value calculation storage unit The radio device, wherein the transmission input signal is distorted in accordance with the amplitude value of the transmission input signal according to the distortion correction value read out, and the transmission output signal in which the output distortion of the transmission amplifier is corrected is output to an antenna. A switch circuit for switching and connecting the output of the transmission amplifier to the feedback circuit having the attenuator or the antenna, and the feedback circuit having the attenuator. A switch circuit for switching to the demodulation circuit to receive an input signal from the transmission output signal or the antenna from, switched to the feedback circuit side for each end of each transmission slot of the transmission input signal.

Further, a memory address calculation circuit included in the distortion correction value calculation storage unit of the wireless device of the present invention calculates an address according to the amplitude value from the transmission input signal, and the distortion correction value storage memory stores the address based on the address. The variable delay device outputs the transmission input signal delayed by delaying the transmission input signal, and the delay detection circuit compares the delayed transmission input signal with the demodulated transmission output signal. The amount of delay of the demodulated transmission output signal is detected and output to the variable delay device, and the distortion correction value calculation circuit compares and calculates the delayed transmission input signal from the variable delay device with the demodulated transmission output signal. And outputs the distortion correction value to the distortion correction value storage memory. Also, the method of using the wireless device of the present invention is such that each switch circuit is switched to a feedback circuit at the end of each transmission slot of a transmission input signal, and a test signal is provided between the transmission slot of the transmission input signal and the transmission slot. A slot is provided, a test signal is input as a transmission input signal for each test signal slot, the test signal is fed back, demodulated, and used as a demodulation transmission input signal to be compared in a distortion correction value calculation storage unit. Correct the output distortion that occurs.

[0011]

1 and 3 show an embodiment of a radio device according to the present invention.
The explanation is given using. As shown in FIG. 3, the normal transmission waveform is the same as the conventional transmission waveform in the transmission slot 3 shown in FIG.
At the timings of 1, 32,..., A preamble signal and a modulated wave of transmission data are transmitted for each slot. The transmission slots 31, 32 shown in FIG.
Is the transmission time of the own channel, but the transmission slot 3
.., 1, 32... Are transmission times of other channels.
In the radio according to the present invention, the transmission slots 31, 3
2... During the transmission time of another channel, that is, the test signal slots 35, 36,... Shown in FIG.
At the timing of..., A test signal as shown as an example in FIG. 3C is fed back from the antenna without being transmitted, and a distortion correction value is calculated using this test signal.

FIG. 1 shows a part of a wireless device. In FIG. 1, reference numeral 1 denotes an input terminal to which a transmission input signal is applied;
Is a memory address calculation circuit for calculating an address, 13
Is a distortion correction value storage memory that stores a distortion correction value, and 2 is a multiplier that multiplies an input transmission input signal by a distortion correction value (an adder may be used, but the following description will be made using the multiplier). 3
Is a DA converter that converts a transmission input signal multiplied by a distortion correction value into an analog signal, 4 is a modulator that modulates a high-frequency signal by an analog signal, 5 is a transmission amplifier that amplifies a modulated signal to a required output, and 9a is a transmission amplifier. A switch circuit for switching the output of the amplifier 5 to the feedback circuit or the antenna 7 side; 6, a duplexer; 8, an attenuator forming a feedback circuit; 9 b, a received signal from the duplexer 6 or a feedback having the attenuator 8. A switch circuit for switching a transmission output signal from the circuit to the demodulator 10; an AD converter 11 for converting a demodulated transmission input signal from the demodulator 10 into a digital signal; and a variable delay device 15 for delaying the input transmission input signal , 12 is a distortion correction value calculation circuit that calculates a distortion correction value from the demodulated transmission input signal and the delayed transmission input signal, and 16 is a delay amount detection circuit that detects the delay amount from the demodulated transmission input signal and the delayed transmission input signal. Delay detection circuit, 17 is a memory address calculation circuit 14, the distortion correction value storage memory 13, variable delay unit 15, the distortion correction value calculation circuit 12, a delay detection circuit 1
6 shows a distortion correction value calculation storage unit constituted by 6.

FIG. 1 shows a part of a radio device according to the present invention. First, a normal transmission operation state will be described. The transmission input signal applied to the input terminal 1 is supplied to a multiplier 2 and a memory address calculation circuit 14 constituting a distortion correction value calculation storage unit 17.
And the variable delay unit 15. The memory address calculation circuit 14 calculates an address corresponding to the input transmission input signal and outputs the calculated address to the distortion correction value storage memory 13. The distortion correction value storage memory 13 calculates the distortion correction value corresponding to the input address by the multiplier 2. Output to The multiplier 2 multiplies the transmission input signal input from the input terminal 1 by the distortion correction value, and
The DA converter 3 converts the transmission input signal multiplied by the distortion correction value into an analog signal and outputs the analog signal to the modulator 4. The modulator 4 modulates a high-frequency signal separately input to the modulator 4 with the input analog signal, and outputs the modulated signal to the transmission amplifier 5.
The transmission amplifier 5 amplifies the input modulated signal to a required output, outputs the transmission output signal to the antenna 7 via the switch circuit 9a and the duplexer 6, and transmits the signal from the antenna 7.

When the transmission of one transmission slot shown in FIG. 3A is completed in the above-described normal transmission operation, the switch circuits 9a and 9b are switched in synchronization with the transmission slot signal, and the attenuator 8 serving as a feedback circuit is switched. And transmission amplifier 5 and demodulator 10
Is connected, the transmission input signal of the input terminal 1 also changes, and a test signal such as that shown in FIG. 3C is input at the timing of the test signal slot shown in FIG. In each device from the terminal 1 to the switch 9a, the signal is processed in the same manner as in the normal transmission described above, and becomes a modulation test signal. Next, the modulation test signal passes through the attenuator 8, which is a feedback circuit, and is input to the receiving unit via the switch circuit 9b. The modulation test signal input to the receiver is demodulated by the demodulation circuit 10 to become a demodulation test signal, and is converted to a digital signal by the A / D converter 11. A / D converter 1
The demodulation test signal from No. 1 is input to the distortion correction value calculation storage unit 17 to calculate and store the distortion correction value. First, the distortion correction value calculation circuit 12 calculates the distortion correction value. However, since the demodulation test signal input to the distortion correction value calculation circuit 12 is delayed, the demodulation test signal and the input test signal are detected by delay. The delay amount is input to the circuit 16, the input test signal input to the variable delay unit 15 is delayed by the detected delay amount, and the phase is adjusted to the demodulation test signal.

Next, a distortion correction value calculation circuit 12 calculates a distortion correction value and outputs it to a distortion correction value storage memory 13. In the distortion correction value storage memory 13, the amplitude of the input signal calculated by the memory address calculation circuit 14 is calculated. The distortion correction value is stored at an address corresponding to the value. With the next input test signal, an address signal corresponding to the amplitude value of the input test signal is output from the memory address calculation circuit 14 to the distortion correction value storage memory 13,
The distortion correction value is output from the distortion correction value storage memory 13 to the multiplier 2. The multiplier 2 corrects the distortion of the next input test signal, and corrects the output of the transmission amplifier 5 so that there is no distortion. 1
When one test signal slot ends, the switch circuit 9
a and 9b are switched and connected to the duplexer 6 side, and the normal transmission operation is performed again.

[0016]

According to the present invention, switch circuits are provided on the input side and the output side of a feedback circuit for attenuating a transmission output signal of a transmission amplifier by an attenuator and feeding it back. In addition to switching to the feedback circuit side, the distortion correction value of the transmission amplifier is calculated using the test signal at the time of the empty slot between each transmission slot, and the distortion correction value based on the test signal is used to calculate the distortion correction value by the output of the transmission amplifier. It is possible to provide a wireless device and a method of using the wireless device that are configured to correct generated distortion, to minimize a calculation error of a distortion correction value calculation, and to calculate a calculation time in a short time in calculating a delay amount. It is valid.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram showing a part of a wireless device according to the present invention.

FIG. 2 is a circuit block diagram showing a part of a conventional wireless device.

FIG. 3 is a diagram showing (a) a timing of a transmission slot, (b) a timing of a test signal slot, and (c) an example of a test signal used in the wireless device according to the present invention.

4A and 4B are diagrams illustrating (a) transmission slot timing and (b) an example of a transmission signal used in a wireless device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... input terminal, 2 ... multiplier, 3 ... DA converter, 4 ... modulator, 5 ... transmission amplifier, 6 ... duplexer, 7 ... antenna, 8 ...
Attenuator, 9a, 9b, 20 switch circuit, 10 demodulator, 11 AD converter, 12 distortion correction value calculation circuit, 13
·································································································· 19 . 31, 32, 41, 4
2 ... transmission slot signal, 35, 36 ... test signal slot, 37, 38, 39 ... test signal, 43 ... preamble signal, 44 ... transmission data.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04B 1/40 H04B 1/04 H04L 27/20 H04L 27/36

Claims (3)

(57) [Claims] 1. A transmission amplifier for amplifying a modulated signal modulated by a transmission input signal, a feedback circuit having an attenuator for feeding back a transmission output signal of the transmission amplifier, and the transmission fed back by the feedback circuit. A distortion correction value calculation storage unit that calculates and stores a distortion correction value by comparing a demodulated transmission output signal obtained by demodulating an output signal with the transmission input signal, wherein the distortion read from the distortion correction value calculation storage unit is provided. A radio device, wherein the transmission input signal is distorted in accordance with the amplitude value of the transmission input signal according to the correction value, and the transmission output signal in which the output distortion of the transmission amplifier is corrected is output to an antenna. A switch circuit for switching the output of the antenna to the feedback circuit or the antenna having the attenuator; and the transmission output signal from the feedback circuit having the attenuator. Or a switch circuit for switching and connecting a reception input signal from the antenna to a demodulation circuit, wherein each switch circuit is switched to a feedback circuit side at the end of each transmission slot of the transmission input signal. . 2. The distortion correction value calculation storage unit according to claim 1, wherein: a memory address calculation circuit that calculates an address from a transmission input signal according to an amplitude value; and a distortion correction value stored by the address. A delay correction value storage memory for reading out the data, a variable delay device for delaying the transmission input signal and outputting the delayed transmission input signal, and comparing the delayed transmission input signal with the demodulated transmission output signal to perform the demodulation transmission. A delay detection circuit that detects an amount of delay of an output signal and outputs the output to the variable delay device; and compares and calculates the delayed transmission input signal and the demodulated transmission output signal from the variable delay device to calculate the distortion correction value. And a distortion correction value calculation circuit that outputs the distortion correction value to the distortion correction value storage memory. 3. The wireless device according to claim 1, wherein each switch circuit is switched at the end of each transmission slot of a transmission input signal, and a test signal slot is provided between the transmission slot of the transmission input signal and the transmission slot. The test signal is input as a transmission input signal for each test signal slot, the test signal is fed back and demodulated, and used as a demodulation transmission input signal to be compared in a distortion correction value calculation storage unit, and generated by a transmission amplifier. A method of using a wireless device, comprising correcting output distortion.