I'd agree with the Wikipedia article, that it sounds like MIMO, in that it requires the beam to have a spatial extent. From the Wikipedia article: > can thus

I'd agree with the Wikipedia article, that it sounds like MIMO, in that it requires the beam to have a spatial extent. From the Wikipedia article: > can thus access a potentially unbounded set of states That's what people originally thought about MIMO. MIMO's not unbounded. The limit to the number of states is related to the surface area of the volume enclosing the antenna, with the unit of distance being the wavelength. A result radio astronomers already knew when the comms people derived it. With absolutely no evidence to back it up, I'd guess that the same limit applies to OAM multiplexing. As an aside, when one expresses physics in terms of information theory my understanding is that the maximum the number of bits that can be stored in a volume of space (also the number of bits requited to completely describe that volume of space) is related to the surface area of the volume with the linear unit being Plank lengths. Is MIMO capacity in some way a fundamental limit in communications? [1] https://physics.stackexchange.com/questions/497475/can-anyone-explain-the-planck-area https://physics.stackexchange.com/questions/497475/can-anyon...