CN102904846A - A Digital Predistortion Processing Method Adapting to Rapidly Changing Signals - Google Patents
A Digital Predistortion Processing Method Adapting to Rapidly Changing Signals Download PDFInfo
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Abstract
The invention discloses a digital pre-distortion processing method adaptive to a quick-change signal. The digital pre-distortion processing method comprises the following steps of: storing one group of training signals in a concurrent processor, when a system is started, sending the training signals to a power amplifier by the concurrent processor, acquiring an input signal and an output signal of the power amplifier to be provided to a serial processor, calculating a filter coefficient of eliminating a memory effect, after the serial processor eliminates time delay, calculating a passband ripple of the system, calculating a coefficient of reversely correcting the filter, providing the coefficient to the concurrent processor for correcting the memory effect; after the system is started, continuously acquiring the input signal and the output signal of the power amplifier by the concurrent processor, updating and correcting a memoryless and nonlinear search table in real time after eliminating time delay and gain difference; and when the system normally works, carrying out memoryless and nonlinear correction on the input signal by the concurrent processor, eliminating the memory effect, and outputting the memory effect to an emitting link. The invention is suitable for the quick-changing modern communication signal, and has the advantages of reducing out-of-band leakage and increasing frequency spectrum utilization rate and system capacity.
Description
Technical field
The present invention relates to the linearizing processing method of power amplifier (power amplifier), particularly a kind of digital pre-distortion processing method that adapts to fast changed signal.
Background technology
Along with the development of radio communication, signal bandwidth is more and more wider, its envelope rise and fall and peak-to-average force ratio also increasing, this has proposed higher linear requirement to post a letter passage, especially frequency mixer and power amplifier of broadband.This mainly is because semiconductor device has inevitable nonlinear characteristic under large-signal, when the broadband sender is operated in the inelastic region, can produce serious intermodulation component, in working band, just can cause the phase mutual interference between signal, outside working band, produce unwanted spectrum leakage.
How improving the system linearity degree is the major issue that broadband system need to solve, in order to solve the problem of the linearity, can adopt three kinds of methods: a kind of is to select suitable superlinearity semiconductor device, design the broadband sender that meets performance requirement, but this method cost is huge, and technical difficulty is very high; Second method is that whole transmission channel is carried out back-off, makes transmission channel be operated in linear zone, and this method greatly reduces the operating efficiency of system; The third method is to adopt linearization technique, namely adopts suitable peripheral circuit, and the non-linear of the passage of posting a letter proofreaied and correct, thereby present on the whole linear amplification effect to input signal at circuit, this method cost is low, and it is also more flexible that device is selected, and is optimal method at present.And in the linearization technique, effectively the simplest with digital pre-distortion (DPD) technology again.In the DPD system, signal is at first proofreaied and correct by a predistorter, then amplifies output delivering to power amplifier again, and the distorted signals characteristic that predistorter produces is opposite with the distorted characteristic of the passage of posting a letter, thereby can offset distortion component, obtain undistorted signal output.
The step that digital pre-distortion is processed normally at the input and output signal of digital baseband collection power amplifier, based on predefined power amplifier model calculating pre-distortion coefficients, is used for pre-distortion with this coefficient again.Digital pre-distortion is processed general Hardware Implementation, use ADC to gather the input and output signal of power amplifier, calculating pre-distortion coefficients carries out in the serial process devices such as DSP or soft nuclear, carrying out in the parallel processing devices such as FPGA or special chip and use pre-distortion coefficients to carry out pre-distortion, is as described in the patent of CN200810114051.1 such as application number.This Hardware Implementation Main Problems is: because the interface rate of DSP receive data is slow, DSP calculates the normally several seconds spent time of pre-distortion coefficients simultaneously, and the speed of pre-distortion hundreds of MHz normally, this that is to say that DSP can not calculate and upgrade pre-distortion coefficients in real time, therefore DSP can only upgrade the pre-distortion coefficient discontinuously, the input and output signal that namely gathers one section power amplifier calculates pre-distortion coefficients, again coefficient is passed to the pre-distortion module, whole process will expend several seconds, and the pre-distortion coefficient that current like this pre-distortion module is used is that the power amplifier inputoutput data before several seconds calculates.And the variation of present mobile communication signal is very fast, a common frame length is the millisecond magnitude, along with user's access with withdraw from, the bandwidth of mobile communication signal and changes in amplitude are very large, mobile communication system often adopts frequency hopping simultaneously, and namely the residing frequency of signal also can within the time period of different frame saltus step occur.All above-mentioned factors have all caused impact to the effect of traditional pre-distortion technology implementation, so that pre-distortion technology is difficult to produce preferably effect under the condition of fast changed signal, successive bands is produced larger interference, thereby reduced capacity and the coverage of mobile communication system.
Summary of the invention
Above-mentioned shortcoming and deficiency in order to overcome prior art the object of the present invention is to provide a kind of digital pre-distortion processing method that adapts to fast changed signal, have solved the conventional digital pre-distortion method and can not be adapted to the soon problem of the modern communications signal of change.
Purpose of the present invention is achieved through the following technical solutions: a kind of digital pre-distortion processing method that adapts to fast changed signal may further comprise the steps:
(1) before system's normal operation, one section training signal x of parallel processing device storage inside
0(t), x
0(t) bandwidth is determined by the maximum bandwidth of the required concern of power amplifier output signal;
Send training signal x by the parallel processing device by transmitting chain when (2) system starts
0(t) give power amplifier, gather power amplifier output signal y by based on feedback link simultaneously
0(t), again with x
0(t) and y
0(t) all send to the serial process device and process, the serial process device is to x
0(t) and y
0(t) do respectively Fourier transform and obtain x
0(f) and y
0(f), with y
0(f) divided by x
0(f) obtain the frequency domain passband fluctuation z of system
0(f), to z
0(f) carry out inversefouriertransform and obtain z
0(t), with z
0(t) send to the parallel processing device;
When (3) system works, gather one section power amplifier input signal x'(t by parallel processor) (x'(t) be the segment signal of x (t), be x'(t) ∈ x (t)) and one section power amplifier output signal y'(t) (y'(t) be the segment signal of y (t), be y'(t) ∈ y (t)), after eliminating time delay and gain inequality, obtain both corresponding relations by amplitude, namely | y ' (t) |=F (| x ' (t) |), make thus look-up table LUT (amp), wherein amp is the amplitude range of power amplifier input signal, and constantly gathers the power amplifier input and output signal and upgrade; The parallel processing device is according to the amplitude of x (t), finds corresponding output LUT (| x (t) |) in LUT (amp), will again
Export to the memory effect correction module, the memory effect correction module is with x (t) and z
0(t) convolution output.
Compared with prior art, the present invention has the following advantages and beneficial effect:
(1) the present invention is decomposed into memory effect elimination and two steps of memoryless Nonlinear elimination with pre-distortion, and the latter can real-time operation in the parallel processing device, thereby realized upgrading pre-distortion coefficients with the speed of Microsecond grade, and a frame length of present mobile communication signal is the millisecond magnitude, therefore the present invention can improve the renewal speed of pre-distortion coefficients greatly, catches up with fast the variation of wireless communication signals.
(2) the present invention adopts the broadband training signal the passband fluctuation of system to be proofreaied and correct before system's normal operation, this just is equivalent to the memory effect of the system of having eliminated, predistortion module just can be applicable to the signal of different bandwidth like this, thus avoided that memory effect causes non-linear.
(3) the present invention has fundamentally solved the conventional digital pre-distortion method and can not be adapted to the soon problem of the modern communications signal of change, no matter how the bandwidth of signal and amplitude change, the present invention can both keep a preferably gamma correction effect, thereby reduced the band external leakage, improved the capacity of frequency spectrum utilization rate and system.
Description of drawings
Fig. 1 is the whole hardware block diagram that the present invention is used to realize the digital pre-distortion processing.
Fig. 2 is the flow chart of digital pre-distortion processing method of the present invention.
Embodiment
Below in conjunction with embodiment and accompanying drawing, the present invention is described in further detail, but embodiments of the present invention are not limited to this.
Embodiment
Fig. 1 is the whole hardware block diagram that present embodiment is used to realize the digital pre-distortion processing, comprises serial process device, parallel processing device, transmitting chain, based on feedback link, power amplifier and antenna.
As shown in Figure 2, the digital pre-distortion processing method of the adaptation fast changed signal of present embodiment may further comprise the steps:
(1) before system's normal operation, one section training signal x of parallel processing device storage inside
0(t), x
0(t) bandwidth is determined by the maximum bandwidth of the required concern of power amplifier output signal;
Send training signal x by the parallel processing device by transmitting chain when (2) system starts
0(t) give power amplifier, gather power amplifier output signal y by based on feedback link simultaneously
0(t), again with x
0(t) and y
0(t) all send to the serial process device and process, the serial process device is to x
0(t) and y
0(t) do respectively Fourier transform and obtain x
0(f) and y
0(f), with y
0(f) divided by x
0(f) obtain the frequency domain passband fluctuation z of system
0(f), to z
0(f) carry out inversefouriertransform and obtain z
0(t), with z
0(t) send to the parallel processing device;
When (3) system works, by one section power amplifier input signal x'(t of the logical collection of parallel processor) and one section power amplifier output signal y'(t), after eliminating time delay and gain inequality, obtain both corresponding relations by amplitude, namely | y ' (t) |=F (| x ' (t) |), make thus look-up table LUT (amp), wherein amp is the amplitude range of power amplifier input signal, and constantly gathers the power amplifier input and output signal and upgrade; The parallel processing device is according to the amplitude of x (t), finds corresponding output LUT (| x (t) |) in LUT (amp), will again
Export to the memory effect correction module, the memory effect correction module is with x (t) and z
0(t) convolution output.
Above-described embodiment is the better execution mode of the present invention; but embodiments of the present invention are not limited by the examples; other any do not deviate from change, the modification done under Spirit Essence of the present invention and the principle, substitutes, combination, simplify; all should be the substitute mode of equivalence, be included within protection scope of the present invention.
Claims (1)
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| CN201210429530.9A CN102904846B (en) | 2012-10-31 | 2012-10-31 | A kind of digital pre-distortion processing method adapting to fast changed signal |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106031111A (en) * | 2014-04-26 | 2016-10-12 | 华为技术有限公司 | Coefficient training device, method and system and base station |
| CN111108685A (en) * | 2017-08-11 | 2020-05-05 | 诺基亚通信公司 | Multi-phase digital signal predistortion in a radio transmitter |
| CN111131105A (en) * | 2019-12-31 | 2020-05-08 | 上海翎沃电子科技有限公司 | Broadband pre-correction method, device and application |
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| CN101478514A (en) * | 2009-01-08 | 2009-07-08 | 福建邮科通信技术有限公司 | Method for implementing digital power pre-distortion |
| WO2010128160A1 (en) * | 2009-05-07 | 2010-11-11 | Nortel Networks Limited | Pre-distortion for a radio frequency power amplifier |
| CN101902258A (en) * | 2009-05-31 | 2010-12-01 | 大唐移动通信设备有限公司 | Method and device for acquiring digital pre-distortion processing parameter |
| CN102077462A (en) * | 2008-07-02 | 2011-05-25 | 伊诺瓦无线电股份有限公司 | Pre-distortion method and device to enhance power utility of power amplifiers in wireless digital communication applications |
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2012
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Patent Citations (4)
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| CN102077462A (en) * | 2008-07-02 | 2011-05-25 | 伊诺瓦无线电股份有限公司 | Pre-distortion method and device to enhance power utility of power amplifiers in wireless digital communication applications |
| CN101478514A (en) * | 2009-01-08 | 2009-07-08 | 福建邮科通信技术有限公司 | Method for implementing digital power pre-distortion |
| WO2010128160A1 (en) * | 2009-05-07 | 2010-11-11 | Nortel Networks Limited | Pre-distortion for a radio frequency power amplifier |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106031111A (en) * | 2014-04-26 | 2016-10-12 | 华为技术有限公司 | Coefficient training device, method and system and base station |
| CN106031111B (en) * | 2014-04-26 | 2019-04-19 | 华为技术有限公司 | A kind of coefficient training device, method, system and base station |
| CN111108685A (en) * | 2017-08-11 | 2020-05-05 | 诺基亚通信公司 | Multi-phase digital signal predistortion in a radio transmitter |
| CN111108685B (en) * | 2017-08-11 | 2023-12-26 | 诺基亚通信公司 | Polyphase digital signal predistortion in a radio transmitter |
| CN111131105A (en) * | 2019-12-31 | 2020-05-08 | 上海翎沃电子科技有限公司 | Broadband pre-correction method, device and application |
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