All communication systems use power amplifiers for transmission purposes. The purpose of the experiment is to become familiar with an algorithmic method called digital pre-distortion that aims to address the nonlinearity of these amplifiers and thereby improve the efficiency of the transmission chain.
The experiment is based on an Intel WiFi card whose performance will be tested using sophisticated Keysight testing equipment. The algorithm for correcting the distortions will be implemented with the help of MATLAB software.
All communication systems use power amplifiers for transmission purposes. The purpose of the experiment is to become familiar with an algorithmic method called digital pre-distortion that aims to address the nonlinearity of these amplifiers and thereby improve the efficiency of the transmission chain.
The experiment is based on an Intel WiFi card whose performance will be tested using sophisticated Keysight testing equipment. The algorithm for correcting the distortions will be implemented with the help of MATLAB software.
Experiment description:
The experiment will take two sessions of about four hours each:
• Study on RF amplifier distortions and the method to cancel the distortion with the help of DPD which inversely distorts the input signal to the amplifier.
• Writing an algorithm in MATLAB that calculates the DPD coefficients for the purpose of linearization of the amplifier. Good knowledge in writing MATLAB software is required.
• Measurement of RF amplifier performance without DPD.
• Measurement of the performance of the RF amplifier after adding the DPD as previously calculated.
In the first session:
Writing the DPD algorithm:
1. A first algorithm that prepares the signals measured at the input and output of the amplifier for the main algorithm of the DPD.
The algorithm ensures that the two signals are at the same power, frequency and phase.
2. A second algorithm which is the main algorithm of the DPD and uses the two signals generated from the first algorithm.
3. Check the algorithm on a synthetically distorted signal.
In the second session:
Running the algorithm on the true output signal of the power amplifier:
1. Measurement of output signal of the RF amplifier using an advanced test equipment.
2. Calculate the DPD using the algorithm from the first session of the experiment.
3. Check the signal quality at the output of the RF amplifier after adding the DPD.
4. Summary and conclusions.
Remarks:
During the experiment, the students should stick to the safety guidelines of the communication laboratory that are published on the website.
Also should stick to the electrical safety instructions that are valid in each laboratory, and are taught in the compulsory course 044102.
