High-speed data transmission high-order modulation compensation power amplifier linear distortion system

Abstract

The application discloses a high-speed data transmission high-order modulation compensation power amplifier linear distortion system and belongs to the technical field of satellite high-speed data transmission. The system comprises a data processing module, a constellation mapping module, a shaping filter module, a quadrature modulation module, a radio frequency up-conversion module, a power amplifier output module, a calculation weighting parameter module and a mapping correction module. The power amplifier output signal is analyzed by a spectrum analyzer, the constellation points after compression of the power amplifier are acquired, the correction parameters are generated by comparison with standard mapping phase points, the constellation mapping is adjusted by the mapping correction module, and the amplitude compression of the peripheral phase points caused by the saturation of the power amplifier is compensated. The application can correct the phase point distribution by digital preprocessing under the working condition of the saturation of the power amplifier, effectively improve the linear distortion of the high-order modulation signal, reduce the power amplifier backoff amount, improve the power amplifier efficiency, and be suitable for the high-order modulation scene of non-amplitude balance in the satellite high-speed data transmission system.

Description

Technical Field

[0001] This invention relates to the field of high-speed satellite data transmission technology, specifically to a high-speed data transmission high-order modulation compensation power amplifier linear distortion system, used for high-speed data modulation transmission under power amplifier conditions. Background Technology

[0002] Currently, the amount of remote sensing satellite data is increasing dramatically. The massive amount of data generated by satellites needs to be transmitted to ground stations during short transit periods. The data transmission rate is mainly constrained by four factors: satellite transmission power, modulation method, antenna gain, and ground receiving capability. This invention aims to solve the linearity distortion problem caused by satellite transmission power and high-order modulation. Summary of the Invention

[0003] In view of this, the present invention provides a high-speed data transmission high-order modulation compensation power amplifier linear distortion system. The technical problem to be solved is that, under the condition of RF power amplifier saturation output, the high-order modulation with unbalanced amplitude will cause the large amplitude phase points to be compressed inward due to the power amplifier being in the saturation operating region, resulting in distortion of the entire phase diagram. Before input to the power amplifier, by changing the distribution of the high-order modulation phase mapping points, the distance between the large amplitude phase points on the periphery and the inner phase points is increased, compensating for the amplitude compression of the peripheral phase points caused by power amplifier saturation, so that after the power amplifier compression, the entire phase point distribution returns to the standard position.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A high-speed data transmission high-order modulation compensation power amplifier linear distortion system includes a data processing module, a constellation mapping module, a shaping filter module, an orthogonal modulation module, an RF up-conversion module, a power amplifier output module, a weighted parameter calculation module, and a mapping correction module.

[0006] The data processing module sends the data after front-end encoding, scrambling, and framing to the constellation mapping module; the constellation mapping module converts the data into I / Q channels containing amplitude and phase and sends the I / Q channels to the shaping and filtering module, which performs shaping filtering according to the selected shaping coefficient; the quadrature modulation module performs intermediate frequency modulation on the shaped data; the intermediate frequency modulated data is converted to digital signal by A / D conversion and then sent to the radio frequency upconversion module, which upconverts the intermediate frequency signal to the final radio frequency, which is then amplified and output by the power amplifier output module;

[0007] The output signal of the power amplifier output module is connected to an external spectrum analyzer for phase point analysis to obtain the constellation points after the power amplifier output. The constellation points generated by the phase point analysis are exported from the spectrum analyzer. The weighted parameter calculation module compares the constellation points generated by the phase point analysis with the standard mapped phase points to generate correction parameters. The mapping correction module weights the amplitude and phase of each phase point with the generated correction parameters and sends them to the constellation mapping module to adjust the mapping, finally obtaining the phase mapping of the power amplifier output module.

[0008] Compared with the prior art, the present invention has the following advantages:

[0009] Traditional high-order modulation with amplitude imbalance uses power amplifier back-off to move the power amplifier's operating point back to the linear region to improve the phase point of the power amplifier output. The disadvantage of power amplifier back-off is that it significantly reduces the power amplifier's transmission efficiency. In this application, high-order modulation with amplitude imbalance uses a method of correcting the phase point distribution position to compensate for the phase point compression caused by power amplifier saturation. The power amplifier back-off amount is small, which improves the utilization rate of the power amplifier under high-order modulation. Attached Figure Description

[0010] Figure 1 This is a principle block diagram of an embodiment of the present invention;

[0011] Figure 2 These are effect diagrams of an embodiment of the invention. Detailed Implementation

[0012] Below, in conjunction with Figure 1 , Figure 2 The present invention will be further described below.

[0013] Reference Figure 1 This embodiment is specifically a high-speed data transmission high-order modulation compensation power amplifier linear distortion system, which includes a data processing module 1, a constellation mapping module 2, a shaping filter module 3, a quadrature modulation module 4, an RF upconversion module 5, a power amplifier output module 6, a phase point analysis module 7, a weighted parameter calculation module 8, and a mapping correction module 9.

[0014] Data processing module 1 sends the data after front-end encoding, scrambling, and framing to constellation mapping module 2; constellation mapping module 2 converts the data into I / Q channels containing amplitude and phase and sends the I / Q channels to shaping and filtering module 3, which performs shaping and filtering according to the selected shaping coefficient; quadrature modulation module 4 performs intermediate frequency modulation on the shaped data; the intermediate frequency modulated data is converted to DA and then sent to RF upconversion module 5, which upconverts the intermediate frequency signal to the final RF frequency, and then amplifies it by the power amplifier output module 6 before outputting it;

[0015] The output signal of the power amplifier output module 6 is connected to an external spectrum analyzer. The phase point analysis module 7 of the spectrum analyzer performs phase point analysis to obtain the constellation points after the power amplifier output. The spectrum analyzer exports the constellation points generated by the phase point analysis. The weighted parameter calculation module 8 compares the constellation points generated by the phase point analysis with the standard mapped phase points to generate correction parameters. The mapping correction module 9 weights the amplitude and phase of each phase point with the generated correction parameters and sends them to the constellation mapping module 2 to adjust the mapping. After adjustment, the phase mapping of the power amplifier output module 6 is obtained and compared with the standard mapped phase points. If the comparison result is not ideal, the phase point analysis is performed again to iterate and generate new weighted parameters, and the mapping correction is performed again.

[0016] This embodiment uses the 16QAM debugging method as an example. Its standard mapped phase point diagram and power amplifier operating point diagram are referenced. Figure 2 The power amplifier operates in the nonlinear region.

[0017] After the standard mapping phase point diagram generated by constellation mapping module 2 is amplified, the output signal is analyzed by a spectrum analyzer to obtain the phase point diagram after power amplifier compression. The phase point distribution characteristics of the phase point diagram after power amplifier compression are that the phase points with large amplitudes have large amplitude compression, among which the four vertices of the rectangle have the largest compression, and the inner circle phase points have smaller compression.

[0018] Based on the phase point diagram after power amplifier compression, the corrected weighting parameters are calculated. The weighting parameters are the two-dimensional coordinate values ​​of 16 phase points. The corrected mapped phase point diagram is obtained by correcting the mapped phase points through the weighted parameters. The characteristic of the corrected mapped phase point diagram is that the phase points with large amplitude further increase the spacing between adjacent phase points to compensate for the compression caused by the power amplifier.

[0019] After the phase points of the modified mapped phase point diagram are amplified by the power amplifier, the output signal of the power amplifier is analyzed by a spectrum analyzer to obtain the output phase point diagram of the power amplifier. The output phase point diagram of the power amplifier is very similar to the standard mapped phase point diagram.

[0020] The above process can be iterated repeatedly until the power amplifier output phase point diagram achieves the desired effect;

[0021] Constellation mapping and mapping correction are implemented in digital processing; phase point analysis is performed using a spectrum analyzer, and the weighting parameters are calculated in Matlab.

[0022] This application utilizes a spectrum analyzer to obtain the offset between the constellation diagram after power amplifier output and the standard constellation diagram. Based on this offset, the phase point positions are corrected during constellation mapping in digital processing, thereby correcting the phase points after power amplifier output and compensating for phase point distortion caused by power amplifier saturation. This invention is applied in high-order digital transmission modulation containing power amplifiers to improve the efficiency of power amplifiers in non-amplitude balanced high-order modulation.

Claims

1. A high-speed data transmission high-order modulation compensation power amplifier linear distortion system, characterized in that, It includes a data processing module (1), a constellation mapping module (2), a shaping filter module (3), a quadrature modulation module (4), an RF upconversion module (5), a power amplifier output module (6), a weighted parameter calculation module (8), and a mapping correction module (9). The data processing module (1) sends the data after front-end encoding, scrambling and framing to the constellation mapping module (2); the constellation mapping module (2) converts the data into I / Q channels containing amplitude and phase and sends the I / Q channels to the shaping filter module (3); the shaping filter module (3) performs shaping filtering according to the selected shaping coefficient; the quadrature modulation module (4) performs intermediate frequency modulation on the shaped data; After the intermediate frequency modulation data is converted to DA, it is sent to the radio frequency upconversion module (5). The radio frequency upconversion module (5) upconverts the intermediate frequency signal to the final radio frequency, which is then amplified by the power amplifier of the power amplifier output module (6) and output. The output signal of the power amplifier output module (6) is connected to an external spectrum analyzer. The phase point analysis module (7) of the spectrum analyzer is used to perform phase point analysis to obtain the constellation point after the power amplifier output. The spectrum analyzer exports the constellation points generated by the phase point analysis. The weighted parameter calculation module (8) compares the constellation points generated by the phase point analysis with the standard mapped phase points to generate correction parameters. The mapping correction module (9) weights the amplitude and phase of each phase point with the generated correction parameters and sends them to the constellation mapping module (2) to adjust the mapping. After adjustment, the phase mapping of the power amplifier output module (6) is obtained, and the phase mapping is compared with the standard mapped phase points. If the comparison result is not ideal, the phase point analysis is performed again, new weighted parameters are iterated, and the mapping correction is performed again. Finally, the phase mapping of the power amplifier output module (6) is obtained.

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