I think spectrum access protocol is a special case of medium access protocol. Medium access protocol can be accomplished also by time division multiple accessing, code division multiple accessing, space division multiple accessing and frequency division multiple accessing which is spectrum access protocol.

Best wishes

Thank You @Abdelhalim Zekry Sir

Agree with Dr Zekry. "Spectrum access" refers specifically to wireless medium access. But in fact, all medium access protocols ultimately address the same problem: sharing spectrum on a given medium. So it should not be surprising that the same techniques are used for wired or wireless (even though wireless creates some extra signal integrity problems).

For example, take the very first standarized coaxial Ethernet, at 10 Mb/s capacity. In fact, that medium used mostly 30 MHz of spectrum, in coax or 10BASE-T twisted pair media. One can postulate multiple such frequency spectra coexisting in a single wired or wireless medium, to show how we are always addressing the same problem.