Or you can have hybrid of anyone of these schemes. Again the application of the medium access resources and assignment techniques could be viewed like this, that one of the primarily applications is the satellite and the cellular mobiles. I have not taken cellular mobiles, I mean taking them as part of the satellites, and on the other hand you have got the local area network.
Satellites today use FDMA, TDMA, space switch TDMA and CDMA. CDMA is random access. SS-TDMA could be demand assigned, or could be pre-assigned, FDMA could be pre-assigned, TDMA could be a pre-assigned, and similarly FDMA and TDMA could be demand-assigned.
On the other hand the local area networks, they use the baseband and broadband access and control techniques, under the baseband you could have TDMA FDMA, once again they could be controlled access like the slotted ALOHA or to compassing, like as you have in the broadcast bus or to compassing in the ring, whereas one could use the bradband techniques, they primarily depend on the frequency division multiple access and time division multiple access.