Here is a summary of the multiple access control and assignment classification. You have multiple access assignment and control. Assignment and control play a very important role for the simple reason that we want to utilise the resource efficiently, that is a maximum throughput, minimum delay. Well you can have fixed assignment, and fixed assignment could have pre-assignment, beforehand you can assign, or it could be a demand assignment. In the pre-assignment category you have the conventional frequency division, time division, space division, code division, multiple access techniques, and hybrid of any one or two or there of them. In the demand assignment category you could have a distributed control or a central control, then FDMA and TDMA could be centrally controlled and allocated based on a certain demand. Or the demand assignment equipment could be placed at all the stations, where you get the distributed control in the FDMA and the TDMA system. You may not like the fixed assignment schemes, and random access becomes quite useful. Users want that any time anywhere, they want to access the medium. For that you have got the ALOHA which is called pure ALOHA, or code division multiple access, as well as the random access technique. In fact, this is another advantage of the CDMA. Or the random access could be controlled access to the various degree of control.

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