WIRELESS COMMUNICATION DEVICE AND OPERATION METHOD
|発明の名称 （英語）||WIRELESS COMMUNICATION DEVICE AND OPERATION METHOD|
|発明の概要（英語）||The present disclosure is a wireless communication device that is capable of reducing cost and size, and an operation method. A predetermined number of strain-compensation signals obtained by subjecting each of a predetermined number of input signals to a strain-compensation process that compensates for strain in a downstream non-linear circuit are up-converted at mutually different frequencies, synthesized, and then amplified and outputted as output signals. On the basis of these output signals, an adjustment unit for adjusting the strain-compensation process performed on the input signals performs a process for inverting the signal spectra of the input signals or feedback signals when the signal spectra is compared with the input signals that correspond to the frequency components of the feedback signals for which the signal spectra are inverted in conjunction with the output signals being down-converted in a feedback unit, the process being performed with respect to the frequency components. The present technique can be used, for example, in a wireless communication device provided with a strain compensation process.|
Conventional, the occurrence of a radio signal to a wireless communication device, the radio signal transmitted from a wireless communication device to avoid the adjacent channel as interference, severely limit the radiation to the adjacent band radio wave is imposed on the method defined.
However, in general, the transmission circuit of the wireless communication apparatus included in the up-converter and the amplifier has non-linearity, so that the time-varying amplitude modulated radio signal and transmitted from the wireless communication device, due to non-linearity inter-modulation distortion (IM: intermodulation) occurs. Therefore, sufficiently reducing the intermodulation distortion of the nonlinear compensation technique becomes important. For example, as a non-linear compensation techniques, a signal input to the non-linear circuit, the reverse characteristic of the nonlinear input-output non-linear circuit so that in the pre-distort, pre-distortion method is used.
Fig. 1 is, in the conventional digital predistortion of the transmission circuit of a configuration example of a non-linear compensation in accordance with the invention.
As shown in Fig. 1, the conventional transmission circuit 11 is, DPD(Digital Pre-Distorter) 12, DAC(Digital to Analog Converter) 13, up-converter 14, local oscillator15, the power amplifier 16, coupler 17, downconverter 18, ADC(Analog to Digital Converter) 19, and a parameter adjusting unit 20 is configured.
The transmission circuit 11 is input to the input signal x, the power amplifier 16 so as to compensate for non-linearity of the pre-distort the digital signal processing is performed by DPD12, v DPD12 as the output from the distortion compensation signal. V is the distortion compensation signal, and converted into an analog signal by DAC13, up-converter 14 by the local oscillation frequency of local oscillator 15 fL mixed and upconverted to radio frequency f, power amplification in the power amplifier 16. At this time, 16 by non-linearity of the power amplifier, the distortion compensation signal DPD12 applied by the distortion is returned to the original v, the input signal x and the output signal of the same waveform as the output from the power amplifier 16. In addition, the output signal is branched by the coupler 17, down converter 18 by the local oscillation frequency of local oscillator 15 fL based on the down-converted to an intermediate frequency. Then, by a wide-to-digital converter ADC19 output signal, feedback signal input to the parameter adjustment unit 20 as y.
The transmission circuit 11 is configured to, in order to perform high-precision non-linear compensation of the digital signal processing is introduced which, in the case where a look-up table DPD12, the amplitude of the input signal x of the output signal of the amplitude value of the vector stored in the lookup table is used. Parameters to the parameter adjustment unit 20 of the look-up table can be adjusted, the transmission circuit 11 in the non-linear compensation of high precision is maintained. In addition, if the operation type is DPD12, the arithmetic circuit of a high degree of accuracy by adjusting the polynomial non-linear compensation is maintained.
On the other hand in recent years, the demand for mobile broadband wireless communication from a significant increase, not only the frequency band of the conventional situation and the bandwidth is insufficient, the addition of a new band has been carried out. However the wide bandwidth to be allocated simultaneously because it is difficult, a plurality of frequency bands used at the same time increasing the equivalent reception band, the carrier, it is contemplated that the introduction of carrier aggregation technology, has been performed. Carrier, carrier aggregation technology in the case where the discontinuous depending on a frequency band used at the same time, a plurality of different frequency bands of the transmitter is to be operated in parallel, when there are a large number of frequency bands, for each frequency band by providing a transmitter is assumed that the manufacturing cost is increased.
Therefore, a single broadband transmitter 1 a plurality of frequency bands considered is amplified at the same time, a nonlinear input-output characteristics for each frequency band are different from each other, for the non-linear compensation, the compensation is required for each frequency band.
Fig. 2 is, the simultaneous transmission of the frequency band 2 and the non-linear compensation according to one embodiment of a transmitting circuit of the prior art in accordance with the invention.
As shown in Fig. 2, the transmission circuit 11A, 2 and 12-2 two DPD12-1, 2 13-2 and two DAC13-1, one of up-converters 14-1 and 14-2 2, 15-2 and 15-1 of the local oscillator 2, power amplifier 16, coupler 17, down converter 18-1 and 18-2 of 2, 2 and 19-2 two ADC19-1, the parameter adjustment unit 20, as well as, the adder 21 a.
In the transmission circuit 11A, an intermediate frequency corresponding to the frequency 2 of the input signal x1 and x2 is, the digital predistortion circuit and the 12-2 both DPD12-1 input. Output from the distortion compensation signal DPD12-1 v1 is, after analog conversion by DAC13-1, 14-1 up-converter local oscillator 15-1 by the local oscillation frequency fL1 and mixed with, the radio frequency f1 up-converted. Similarly, output from the distortion compensation signal DPD12-2 v2 is, after analog conversion by DAC13-2, 14-2 up-converter local oscillator 15-2 by the local oscillation frequency fL2 and mixed with, the radio frequency f2 up-converted.
In this way, different radio frequency f1 and f2 up-converted by the distortion compensation signal v1 and v2 the adder 21 are combined by an adder, a non-linear circuit 16 is power-amplified in the power amplifier. At this time, 16 by non-linearity of the power amplifier, distortion compensation signal v1 and v2 returns to the original distortion, the input signal x1 and x2 same waveform as that of the output signal is outputted.
In addition, the output signal output from the power amplifier 16, branched by the branching coupler 17, down converter 18-1 and supplied to the 18-2. Then, the output signal, the down-converter 18-1 by the local oscillation frequency of local oscillator 15-1 fL1 based on the down-converted to an intermediate frequency, and converted into digital by ADC19-1, the feedback signal y1 as input to the parameter adjustment unit 20. Similarly, the output signal, the down-converter 18-2 by the local oscillation frequency of local oscillator 15-2 fL2 based on the down-converted to an intermediate frequency, and converted into digital by ADC19-2, the feedback signal y2 as input to the parameter adjustment unit 20. Therefore, the parameter adjustment unit 20, the feedback signal y1 and the feedback signal y2 is used, and 12-2 look-up table type DPD12-1 case, by adjusting the parameters of each of the look-up table, the transmission circuit 11A with high accuracy in the nonlinear compensation is maintained. It should be noted that, in the operation type is 12-2 and DPD12-1 case, by adjusting the polynomial arithmetic circuit is a high-precision non-linear compensation is maintained.
In this way, conventionally, the frequency corresponding to the transmission circuit 11A is 2, the output signal of the two sets of a feedback circuit for feeding back (down-converter 18-1 and 18-2 and 19-2 as well as ADC19-1) may need to be provided. For example, to the predistorter disclosed in Patent Document 1 also, similar to the transmission circuit 11A, one ADC 2 is configured with.
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ARIPO: BW GH GM KE LR LS MW MZ NA RW SD SL SZ TZ UG ZM ZW
EAPO: AM AZ BY KG KZ RU TJ TM
EPO: AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR
OAPI: BF BJ CF CG CI CM GA GN GQ GW KM ML MR NE SN ST TD TG
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