
The book is now in 2nd edition, and I've both of the 1st and 2nd editions, it's really a masterpiece.
The 2nd edition covers many of the 'gotchas' of OFDM implementation and covers several error detection and correction techniques, that're not in the 1st edition.
Modern PHY is like bit twiddling in programming, 99% programmer don't do it and don't care unless you are doing HPC or device driver. In networking those who're doing PHY belong to communication engineering field. For modern networking the relevant PHY mostly dealing with digital I/Q signal for wired/wireless and there are many excellent books on the subject such as this [2].
[1]The Art of Electronics (2015):
https://news.ycombinator.com/item?id=38748370
[2] Digital Signal Processing in Modern Communication Systems
https://www.amazon.com/Digital-Signal-Processing-Communicati...
1) For general applied and engineering Maths book perhaps you can look into both textbooks by Prof. Kuldeep Singh and they uses Matlab but Octave should be fine [1].
a) Engineering Mathematics Through Applications b) Linear Algebra
2) For signal processing especially for communication I'd highly recommend "Digital Signal Processing in Modern Communication Systems" by Andreas Schwarzinger. It introduces the modern communication systems from the first principles to the more applied OFDM systems with examples that can be run using either Matlab or Octave. Just get the book it's really good even if you're not interested in communication systems.
3) If you want to learn more advanced applied engineering books on signal processing I'd recommend reading books on time-frequency techniques both linear and non-linear. For introduction check the book "Explorations in Time-Frequency Analysis" by Patrick Flandrin. Time-frequency analysis is most probably going to be pervasive very soon for increasing the accuracy of AI and ML by providing better intermediate processing of data features.
There is an interesting project for open source LoRa physical layer implementation in GNU Radio. The authors had to reverse engineer the LoRa physical layer for the implementation because it is proprietary unlike the data link layer LoRaWAN part of it [2].
[1]Digital Signal Processing in Modern Communication Systems:
https://www.amazon.com/Digital-Signal-Processing-Communicati...
[2]LoRa PHY based on GNU Radio: