Week 1 : Creation of gr-dpd & addition of PA blocks

I started working on the project with a healthy initial discussion and calls with my mentors. I have worked out to review my development plan and considered advices to come up with a better development sequence for various parts of project.

I have gone through the theoretical aspects of the “Digital Pre-Distortion” considering various references which are mentioned in my proposal.

To recall as in my proposal, I mainly studied the PA (Power Amplifier) modelling methods using: MP (Memory Polynomial) and GMP (Generalised Memory Polynomial).

Further, I took a brief go through of Adaptive Algorithms for DPD mainly: RLS (Regularised-Least Square) & LMS (Least Mean Square) and the static LUT (Look-Up Table) based algorithm.

Some of the major works that have been commited to the gr-dpd – GNU Radio repository are:

  • Initial commit involving the Directory Structure of the gr-dpd, CMakeLists.txt and some basic API stuff created using gr_modtool.
  • Addition of the new block, i.e., MP_model_PA involving a Memory Polynomial based Power Amplifier implemented.

Here is the relation between input and output signal of MP based model:

The before/after Spectrum plot for MP_model_PA (Order=2 and Memory Depth=2):
  • Addition of the new block, i.e., GMP_model_PA involving a Generalised Memory Polynomial based Power Amplifier implemented.

Here is the relation between input and output signal of MP based model:

The before / after Spectrum plot for GMP_model_PA (K_a=1, L_a=1, K_b=2 , M_b=2, L _b=2 )
  • Addition of the Example flowgraphs involving the above two blocks.

Further tasks proposed are:

  • Going through the complete workflow and mathematical aspects of Learning algorithms.
  • Trying to implement some basic working code on some raw input for Pre-Distortion.

Here is a link to the gr-dpd repository at GNU Radio GitHub.

Any kind of advice or suggestions on my project workflow and tasks are appreciable.

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