It's a good but hard question... Because cellular is huge.
In a professional context, nobody knows it all in details. There are specializations: core network and RAN, and inside RAN protocol stack vs PHY, and in PHY algos vs implementation, etc.
It's about as readable as it can get. The PHY part is pretty awful by comparison. If you have a PHY interest, you'll need to look for technical books as the specs are quite hermetic (but it's not my field either).
In a professional context, nobody knows it all in details. There are specializations: core network and RAN, and inside RAN protocol stack vs PHY, and in PHY algos vs implementation, etc.
You can see all the cellular specs (they're public) from there: https://www.3gpp.org/specifications-technologies/specificati...
5G (or NR) is the series 38 at the bottom. Direct access: https://www.3gpp.org/ftp/Specs/archive/38_series
It's a lot ;) But a readable introduction is the 38.300 spec, and the latest edition for the first 5G release (R15, or "f") is this one: https://www.3gpp.org/ftp/Specs/archive/38_series/38.300/3830...
It's about as readable as it can get. The PHY part is pretty awful by comparison. If you have a PHY interest, you'll need to look for technical books as the specs are quite hermetic (but it's not my field either).