CN106712728A - Method for compensating power amplifier predistortion in satellite communication - Google Patents
Method for compensating power amplifier predistortion in satellite communication Download PDFInfo
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- CN106712728A CN106712728A CN201510775780.1A CN201510775780A CN106712728A CN 106712728 A CN106712728 A CN 106712728A CN 201510775780 A CN201510775780 A CN 201510775780A CN 106712728 A CN106712728 A CN 106712728A
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Abstract
The invention relates to a method for processing signals in satellite communication, and discloses a method for compensating power amplifier predistortion in the satellite communication. In the invention, the adopted predistortion compensation method is based on an adaptive indirect learning architecture of software radio, which can directly identify model parameters of a predistorter without identifying a model of an amplifier in advance, and the structure is simple. The predistorter of the structure has the exact same structure as a predistortion training network. The method comprises the following steps: taking the output of the amplifier as the input of the training network after scale transformation; comparing the output of the training network with the input sampling of the amplifier; applying an error to the adaptation of the predistorter; and when the training network is converged, completely copying parameters of the training network to the predistorter, wherein by periodically replacing coefficients, the predistorter can be adapted to the slow change of power amplifier characteristics.
Description
Technical field
The present invention relates to process signal method, the method for more particularly to a kind of power amplifier predistortion compensation in satellite communication.
Background technology
Satellite communication has a wide coverage, and communication distance is remote, the features such as construction speed is fast, it has also become a kind of important communication means of modern society.In mobile satellite communication system, it is desired to which system carries out strict Power Control, the problem is especially must take into consideration in power limited.
In satellite communication of the prior art, in order to improve the power efficiency of satellite platform to resist many warps and shadow fading, it is desired to which travelling-wave tube amplifier is tried one's best and is operated near saturation point, and this just inevitably introduces non-linear distortion.In addition, when bandwidth and multicarrier application is considered, amplifier can also produce nonlinear distortion with memory.
In satellite communication system, to reach launch requirements, signal need to have power higher, therefore need to be amplified radiofrequency signal by high power amplifier, to obtain signal power high.To improve the power of RF power amplification, power amplifier is often operated in nonlinear state, non-linear distortion occurs.
Power amplifier has amplitude-amplitude and Amplitude-Phase distorted characteristic, and the distortion of this non-linear generation has severely impacted the quality of communication.In current satellite communication system, in order to increase transmission rate and channel capacity, the digital modulation formats with high spectrum utilization of complexity are employed.Using these digital modulation formats, the change of signal envelope generates memory effect, and this memory effect introduces bigger band external diffusion, increases monkey chatter, while also generating inband distortion, causes bit error rate more serious.When RF power amplification is designed, in addition to meeting the requirement of power amplifier power output, efficiency and the linearity are two factors that must take into consideration, but the efficiency and the linearity of power amplifier are mutually contradictory.
In order to be described more fully the present invention, satellite communication model is first introduced, as shown in figure 1, comprising the following steps that.
Step 101, ICBM SHF satellite terminal emitter transmitting radiofrequency signal.
Step 102, SQRC（Square root raised cosine filter）It is filtered.
Step 103, TWT（Travelling-wave tubes）High power amplifier carries out power amplification.
Step 104, SQRC is filtered again to the signal amplified by TWT.
Step 105, judges and sampling.
Found through analysis, there are the following problems for prior art:
Non-linear distortion can increase the bit error rate in satellite communication, signal spectrum extension is produced monkey chatter and use FDMA（Frequency division multiple access, frequency division multiple access）When multicarrier intermodulation.Therefore, the nonlinear compensation to power amplifier is extremely important for the performance of whole satellite communication.
In the prior art, linearisation purpose is reached by the inverse characteristic in amplifier front construction non-linear distortion, that is, using adaptive digital pre-distortion compensating technique amplifier nonlinearity distortion.At present, the research to pre-distortion technology is confined to memoryless nonlinear amplifier mostly, but when the memory effect of amplifier is considered, if still using traditional memoryless pre-distortion technology, nonlinear compensation mechanism may fail.
The content of the invention
The self adaptation of predistorter uses indirect learning architecture in this project, it is not necessary to which first picking out the model of amplifier just can directly pick out the model parameter of predistorter, simple structure.The predistorter of this structure has identical structure with predistortion training grid.
In order to solve the above technical problems, embodiments of the present invention provide a kind of method of the power amplifier predistortion compensation in satellite communication, comprise the steps of：
The output of amplifier is using by the input after change of scale as training network；
The output of training network is compared with the input sample of amplifier；
Error is used for the self adaptation of predistorter；
After training network is restrained, you can the parameter of grid will be trained to be completely copied to predistorter；
Predistorter, can be with the slowly varying of self adaptation power amplifier characteristic by periodically changing coefficient.
Brief description of the drawings
Fig. 1 is satellite communication illustraton of model in the prior art；
Fig. 2 is the system block diagram in embodiment of the present invention；
Fig. 3 is the predistortion module figure in embodiment of the present invention；
Fig. 4 is the predistortion flow chart in embodiment of the present invention.
Specific embodiment
To make the object, technical solutions and advantages of the present invention clearer, embodiments of the present invention are explained in detail below in conjunction with accompanying drawing.However, it will be understood by those skilled in the art that in embodiments of the present invention, in order that reader more fully understands the application and proposes many ins and outs.But, even if many variations and modification without these ins and outs and based on implementation below, it is also possible to realize the application each claim technical scheme required for protection.
Embodiments of the present invention are related to a kind of method of the power amplifier predistortion compensation in satellite communication, and idiographic flow is as shown in Fig. 2 comprise the steps of.
Step 201, in the predistortion adjusting stage, wireless signal through constellation point, then through pulse shaping filter, sampling etc. process after, produce predistorter input signal.Predistortion correction is carried out in this step.After predistortion correction, by predistorter output signal.
Step 202, using the output signal in previous step as input, carries out orthogonal modulation after digital-to-analogue conversion.
Step 203, radio-frequency power amplification is carried out through the signal after ovennodulation in this step.After signal amplifies, it is transmitted by antenna.
Step 204, the signal sent out in previous step can also be received oneself.The output signal for obtaining power amplifier in this step carries out quadrature demodulation.
Step 205, to demodulated signal sampling, then it is compared with input signal, and self-adaptative adjustment is carried out to difference.The value for obtaining is used for the self-adaptative adjustment of predistorter, it is determined that to " the predistortion correction degree " of next secondary data.
In order to introduce the present invention in more detail, described in the way of functional module with reference to embodiment, for simplicity, other details unrelated to the invention are no longer illustrated and described in satellite communication.
In the present embodiment, digital baseband predistorter includes straight-polar coordinates conversion module 301, searches
Table module 302, controller module 306, adaptation module 307, up-converter module 303, radio frequency knot power amplifier module 304 and down conversion module 305.It is specific as shown in Figure 3.
Directly-polar coordinates conversion module 301 is responsible for the rectangular co-ordinate of signal and polar conversion.
Look-up table means 302 are responsible for carrying out " predistortion " signal after conversion.
Controller module 306 is then responsible for the collaborative work of modules.
Adaptation module 307, ensure that predistortion function can apply to a variety of power amplifiers, and after power amplifier long-time use, the performance change caused with temperature change, device aging, device can be pre-distorted to capture and relock, so that property retention stabilization.
The present embodiment design has 5 look-up tables, and straight-polar coordinates conversion module 301 has three less look-up tables.There are two larger look-up tables in addition, the effect of look-up table means 302 exactly carries out the distortion opposite with power amplifier, offseted with the distortion of power amplifier, realize the overall linearisation of system.The input of the module has two groups of signals, and the respectively amplitude and phase of primary signal, and adaptation module is for the same group of self-adaptative adjustment value of primary signal.
The input one of adaptation module has three pairs:The output amplitude and phase of directly-polar coordinates conversion module 301, this is both original value, is also ideal value；The output amplitude and phase of radio frequency power amplification modules 304, this is actual value;The output amplitude and phase of look-up table means 302, this is a reference value of iteration.
In order that the embodiment becomes apparent from, this method is described in the way of handling process below, as shown in figure 4, comprising the following steps that.
Step 401, prepares radio-frequency transmissions.Predistorter uses indirect learning architecture, it may not be necessary to which first picking out the model of amplifier just can directly pick out the model parameter of predistorter.
Step 402, makes training grid have identical structure with predistorter.
Step 403, recognizes predistorter model parameter.
Step 404, judges whether identification predistorter model parameter succeeds.If successfully recognized, subsequent step is performed；Otherwise return to step 403 is retried.
Step 405, the output of amplifier is using by the input after change of scale as training network.
Step 406, trains Grid Sampling.
Step 407, amplifier sampling.The output of training network is compared with the input sample of amplifier.
Step 408, obtains sampled value.
Step 409, after the output of training network is compared with the input sample of amplifier, error is used for the self adaptation of predistorter.
Step 410, convergence training grid.
Step 411, will train the parameter of grid to be completely copied to predistorter.Predistorter, can be with the slowly varying of self adaptation power amplifier characteristic by periodically changing coefficient.
Step 412, completes emission of radio frequency signals.
The step of various methods are divided above, are intended merely to describe clear, a step can be merged into when realizing or some steps are split, and are decomposed into multiple steps, as long as comprising identical logical relation, all in the protection domain of this patent；To adding inessential modification in algorithm or in flow or introducing inessential design, but the core design of its algorithm and flow is not changed all in the protection domain of the patent.
It will be understood by those skilled in the art that the respective embodiments described above are to realize specific embodiment of the invention, and in actual applications, can to it, various changes can be made in the form and details, without departing from the spirit and scope of the present invention.
Claims (1)
1. a kind of method that power amplifier predistortion in satellite communication is compensated, it is characterised in that comprise the steps of：
The output of amplifier is using by the input after change of scale as training network；
The output of training network is compared with the input sample of amplifier；
Error is used for the self adaptation of predistorter；
After training network is restrained, you can the parameter of grid will be trained to be completely copied to predistorter；
Predistorter, can be with the slowly varying of self adaptation power amplifier characteristic by periodically changing coefficient.
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| CN201510775780.1A CN106712728A (en) | 2015-11-15 | 2015-11-15 | Method for compensating power amplifier predistortion in satellite communication |
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| CN201510775780.1A CN106712728A (en) | 2015-11-15 | 2015-11-15 | Method for compensating power amplifier predistortion in satellite communication |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107770111A (en) * | 2017-12-08 | 2018-03-06 | 航天恒星科技有限公司 | Pulse-shaping combination digital pre-distortion suppresses OFDM peak-to-average ratio System and method for |
| CN111181499A (en) * | 2020-01-17 | 2020-05-19 | 南通大学 | Digital predistortion adaptive processing method and system for sea area access equipment |
-
2015
- 2015-11-15 CN CN201510775780.1A patent/CN106712728A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107770111A (en) * | 2017-12-08 | 2018-03-06 | 航天恒星科技有限公司 | Pulse-shaping combination digital pre-distortion suppresses OFDM peak-to-average ratio System and method for |
| CN111181499A (en) * | 2020-01-17 | 2020-05-19 | 南通大学 | Digital predistortion adaptive processing method and system for sea area access equipment |
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Application publication date: 20170524 |