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In a DAMA system, the network allocates
communications bandwidth to each call
from a pool of frequency channels
on a demand-assigned basis. When a
caller at a remote terminal requests
service the request is made to a Network
Control System (NCS) over the shared
DAMA common signalling channel. The
NCS functions as a "switchboard in
the sky". The NCS determines if the
call is valid and then establishes
the channel (including bandwidth)
between the originating site and the
called number. Circuits remain active
only as long as needed, then are broken
to free bandwidth for other users.
When the call is completed, the NCS
is informed by the remote terminals
and the freed bandwidth is returned
to the frequency pool. By using a
DAMA system a single transponder can
support several thousand subscribers.
Any remote unit can be configured
to perform as the Network Control
System with the addition of some hardware
and Network Management System (NMS)
software. The hardware, together with
the NMS, serves as the single focal
point for system level control within
the satellite communications network.
The NCS can be located anywhere within
the satellite footprint.
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DAMA systems quickly and transparently assign communication links or circuits to users on a call-by-call basis. After use (hang up), channels are immediately returned to the central pool, for reuse by others. By using DAMA, many subscribers can be served using only a fraction of the satellite resources required by dedicated, point-to-point Single-Channel-Per-Carrier (SCPC) networks.
The business case for DAMA is a strong one. DAMA saves satellite users money, optimises use of scarce satellite resources, and can increase service provider revenues. Service providers using DAMA are able to pack more services into the same satellite bandwidth, with a resulting increase in their profit-making opportunities. For military applications, many users compete for very limited communications resources. DAMA's inherent network management capabilities provide positive control of those resources.
Bottom Line�.
DAMA systems are versatile, reduce communication costs, and provide the customer total control of their satellite-based network.
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