Simplex and Duplex are types of ______?
Well, perhaps I should've browsed the web a bit longer.

I've found multiple sources that use the following:


transmission mode
data transmission mode
transmission mode type


Some sources:

http://ccm.net/contents/701-data-transmission-transmission-modes

http://www.studytonight.com/computer-networks/transmission-mode

http://greatinformer.blogspot.com/2012/11/data-transmission-modes-types-of-data.html