Interestingly, optical was one of the PHYs for the original 802.11: indirect (diffuse) infrared. I think the idea was that the AP and the individual nodes would

Interestingly, optical was one of the PHYs for the original 802.11: indirect (diffuse) infrared. I think the idea was that the AP and the individual nodes would communicate by scatter off the office ceiling. (The other two PHYs were FHSS and DSSS on 2.4GHz, the latter of which morphed into the 802.11b that gained wide popularity.)