DIGITAL PREDISTORTION PROCESSING METHOD AND SYSTEM

• US 20150358039A1
• Filed: 12/25/2013
• Published: 12/10/2015
• Est. Priority Date: 01/16/2013
• Status: Active Grant

• Current Assignee: Datang Mobile Communications Equipment Company Limited (China Information Communication Technology Group Co. Ltd.)
• Original Assignee: Datang Mobile Communications Equipment Company Limited (China Information Communication Technology Group Co. Ltd.)
• Inventors: Xue, Bin, Xiong, Jun, Zhang, Yongli
• Granted Patent: US 9,450,621 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H03F 1/3247 using feedback acting on predistortion circuits H03F1/3264 takes precedence
• CPC Class Codes: H04B 1/0475 with means for limiting noise, interference or distortion H04B1/0483 takes precedence
• CPC Class Codes: H04B 1/62 for providing a predistortion of the signal in the transmitter and corresponding correction in the receiver, e.g. for improving the signal/noise ratio
• CPC Class Codes: H04B 2001/0433 with linearisation using feedback
• CPC Class Codes: H04L 25/49 using code conversion at the transmitter; using predistortion; using insertion of idle bits for obtaining a desired frequency spectrum; using three or more amplitude levels ; Baseband coding techniques specific to data transmission systems spectral shaping H04L25/03828
• CPC Class Codes: H04L 27/368 adaptive predistortion

Abstract

A digital predistortion processing method and system comprises extracting from a predistortion coefficient parameter table a predistortion parameter corresponding to an input signal, so as to predistort the input signal and obtain a forward transmission signal; amplifying the power of the forward transmission signal to obtain an output signal; acquiring the output signal to obtain a feedback signal; delaying a predetermined number of sampling points so as to acquire the forward transmission signal and obtain a reference signal; conducting synchronization-related calculation on the reference signal and the feedback signal, and calibrating the feedback signal; training a predistortion coefficient according to the reference signal and the calibrated feedback signal; and forming the predistortion coefficient parameter table according to the predistortion coefficient and the amplitude of the input signal. The present invention can delay a predetermined number of sampling points for a transmission signal, thus greatly improving radio frequency index (ACPR).

Claims

1. A digital predistortion processing method, comprising:

extracting a predistortion parameter corresponding to an input signal from a predistortion coefficient parameter list to perform predistortion processing with a predistortion processor on the input signal to obtain a forward sending signal;

performing power amplification processing with a power amplifier on the forward sending signal to obtain an output signal;

collecting the output signal with a receiving end capture data controller to obtain a feedback signal;

collecting the forward sending signal with a sending end capture data controller after delaying for a preset number of sampling points to obtain a reference signal;

performing synchronous correlation calculation with a synchronous correlation processor on the reference signal and the feedback signal to calibrate the feedback signal;

training a predistortion coefficient with a predistortion coefficient training module according to the reference signal and the calibrated feedback signal; and

forming a predistortion coefficient parameter list in predistortion parameter memory according to the predistortion coefficient and the amplitude of the input signal.

2. The method of claim 1, wherein the step of performing synchronous correlation calculation on the reference signal and the feedback signal to calibrate the feedback signal further comprises:

performing the synchronous correlation calculation on the reference signal and the feedback signal to achieve delay calibration, amplitude calibration and frequency calibration of the feedback signal and obtain the maximum peak point information of correlated peaks; and

performing phase calibration on the feedback signal via the phase of a signal corresponding to the maximum peak point.

3. The method of claim 2, wherein before performing the synchronous correlation calculation, the method further comprises a step of judging the power of the feedback signal, if the power of the feedback signal is not less than a set power threshold, continuing to implement the subsequent steps;

otherwise, indicating that the feedback signal is abnormal, and terminating the method.

4. The method of claim 2, wherein the maximum peak point information of correlated peaks comprises the amplitude of the maximum peak of the correlated peaks, and the step of obtaining the maximum peak point information of the correlated peaks comprises:

judging whether the amplitude of the maximum peak of the correlated peaks is larger than a set threshold, if so, continuing to implement the subsequent steps;

if not, finding the maximum peak point information of the correlated peaks again.

5. The method of claim 2, wherein after the step of performing amplitude calibration on the feedback signal, the method further comprises:

judging whether the peak power of the feedback signal after amplitude calibration is lower than a set value of reference signal peak power, if not, continuing to implement the subsequent steps;

if so, indicating that the feedback signal is excessively compressed, and terminating the method.

6. The method of claim 1, wherein the step of collecting the output signal to obtain the feedback signal comprises:

removing the rated linear gain of the collected output signal to obtain the feedback signal.

7. The method of claim 1, wherein the preset number in the delaying for a preset number of sampling points is an integer from −

5 to 5.

8. The method of claim 7, wherein the preset number is 1 or 2.

9. The method of claim 1, wherein the step of training the predistortion coefficient according to the reference signal and the calibrated feedback signal comprises:

figuring out the predistortion coefficient by using a memory polynomial model.

10. A digital predistortion processing system, comprising:

a predistortion processor, configured to extract a predistortion parameter corresponding to an input signal from a predistortion coefficient parameter list to perform predistortion processing on the input signal to obtain a forward sending signal;

a digital to analogue converter and a radio frequency transmission channel, configured to perform digital to analogue conversion on the forward sending signal and send the forward sending signal to a power amplifier;

the power amplifier, configured to perform power amplification on the forward sending signal after digital to analogue conversion to obtain an output signal;

a radio frequency receiving channel and an analogue to digital converter, configured to receive the output signal, perform analogue to digital conversion on the output signal and send the output signal to a receiving end capture data controller;

the receiving end capture data controller, configured to collect the output signal after the analogue to digital conversion to obtain a feedback signal; and

a sending end capture data controller, configured to collect the forward sending signal after delaying for a preset number of sampling points to obtain a reference signal, and send the reference signal to a synchronous correlation processor;

the synchronous correlation processor, configured to perform synchronous correlation calculation on the reference signal and the feedback signal, calibrate the feedback signal, and then send the feedback signal to a predistortion coefficient training module together with the reference signal;

the predistortion coefficient training module, configured to train a predistortion coefficient according to the reference signal and the calibrated feedback signal, and send the predistortion parameter to a predistortion parameter memory and the predistortion processor; and

the predistortion parameter memory, configured to form a predistortion coefficient parameter list according to the predistortion coefficient and the amplitude of the corresponding input signal.