What Does Permanently Assigned Multiple Access Mean?
Permanently Assigned Multiple Access (PAMA) is one of the two major techniques used to allocate channels to users.
In PAMA, every user is assigned a fixed channel, irrespective of whether it is used or not. This is very inefficient as the channels are allotted to users even when there is no requirement.
Therefore, the majority of multiple-access systems make use of demand-assigned multiple access (DAMA), where the available channels are assigned to users on an "as-required" basis.
PAMA is also known as Fixed Assigned Multiple Access (FAMA).
Techopedia Explains Permanently Assigned Multiple Access
The PAMA protocols are considered the most effective techniques for those satellite networks with a small number of terminals (for example, less than 10) having stable as well as predictable traffic patterns.
A PAMA protocol can be employed on a frequency, code, or time basis. Key techniques are Frequency Division Multiple Access (FDMA), Code Division Multiple Access (CDMA), and Time Division Multiple Access (TDMA).
In PAMA, the capacity assignment is allocated in a fixed mode between various stations. The fluctuation in demand can result in considerable underuse of capacity.
On the contrary, in DAMA, the capacity assignment is modified as required to respond in a best way to demand modifications among the various stations.
Advantages of PAMA:
- Perfect for constant-bit-rate-type sources
- Straightforward scheduler
- Channel usage is contention-free
Disadvantages of PAMA:
- Considerable bandwidth usage
- Not flexible while working with terminals having variable bit rates
