TABLE OF CONTENTS Multiple access allows multiple users in the same bandwidth, satellite, and antenna system. Two basic methods are used to allow for multiple users.
The first method is a multiplexing scheme called preassigned multiple access (PAMA). This method permanently assigns a user to a channel or time. An example of a PAMA is using time slots and assigning a given time slot to each end user. Since they are permanently assigned, the users will have that given time slot and will be multiplexed with all of the other users similar to a TDM used in other communication links.
The second method of multiplexing is demand assigned multiple access (DAMA). This system is a true multiple access scheme similar to TDMA used in other communication links. It is used on an as needed basis, i.e., each user takes any time slot when needed.
Another method of providing multiple users is FDM/FDMA. These methods use frequency division to provide multiple users for one band. In systems that incorporate FDMA, the channels are separated using different frequency slots for different users.
