For satellites to gain a foothold in the delivery of advanced broadband services, seamless interconnectivity with terrestrial networks is imperative. For best results, the network should be designed to exploit the unique virtue of satellite in geostationary orbit, namely that it can be a shared resource available, as needed, to many users spread over a very large proportion of the Earth's surface. This is the concept of bandwidth-on-demand. In an ideal network, each terminal communicates with all others (full-mesh connectivity), but utilises satellite capacity only on an as-needed basis. Such an architecture can be implemented if the terminals operate in a Time Division Multiple Access (TDMA) mode (transmit in bursts) and are capable of doing this at a variety of different frequencies (FDMA and TDMA).

The DAMA System (Demand Assigned Multiple Access)

A DAMA System is typically a mesh network that allows direct connection between any two nodes in the network, sharing the bandwidth of a satellite transponder space which can be allocated to each remote terminal as required. DAMA supports full mesh, Point-to-Point or Point-to-Multipoint communications, any user can connect directly to any other user anywhere within the network, and the most superior systems achieve this with TDMA. The result is economical and flexible bandwidth sharing with any mix of Voice, Fax, Video and Data traffic. The key point is that DAMA optimizes the use of satellite capacity by allocating satellite resources to each active node upon demand. By using a DAMA System, satellite resources can support a very much larger number of users.