I do signal processing for wireless communication systems and write about it at https://wirelesspi.com.

You can learn more about DSP principles applied to wireless communications (i.e., SDRs) from my book https://wirelesspi.com/book.

And/or by taking a course that leads to hands on implementation of single and multi-carrier (OFDM) systems at https://wirelesspi.com/course.

I have also written about the main technologies behind 5G physical layer at https://wirelesspi.com/5g-phy.

You can reach Qasim via e-mail using info at wirelesspi dot com.