Another way to do spatial reuse
GPS supports up to 30 (24 typ) simultaneous transmissions all at L1 (~1.5 GHz). It uses orthogonal Gold codes to separate the 30 simultaneous signals. To a receiver there are 29 received sources of noise and 1 desired signal when "Gold-tuned" to the desired signal... I know this is not OAM but still in the domain of spatial reuse..
http://en.wikipedia.org/wiki/GPS_signals