Hi, original presenter here :) The beginning is FTs 101. The end gets more application-centric around OFDM and is why it feels 'unreasonably effective' to me. If it feels obvious, there's a couple of slides at the end that are food for thought jumping off points. And if that's obvious to you too, let's collab on building an open source LTE modem!

If one wants to contribute to an open-source LTE modem, the best place to start may be OpenLTE: https://en.wikipedia.org/wiki/OpenLTE The core of any LTE modem is software, even if it is written for DSPs or other low-level software.