 for backhaul of wireless networks but it has not seen an uptake either in Asia or in US largely due to unavailability of required frequencies. The details on LMDS can be found in [9]. 7.3.6 VSAT upgrade with DVB-S2/DVB-RCS The Satellite VSAT (Very Small Aperture Terminal) system is only one of the few viable, but costly backhaul options for remote or scattered areas connectivity. In recent years two-way satellite broadband VSAT systems based on DVB-RCS (Digital Video Broadcasting - Return Channel via Satellite) standard started to appear in the market. VSAT implements DAMA (Demand Assigned Multiple Access) for high- speed Internet access services. DAMA is a technology used to assign a bandwidth to clients who don't need to use it constantly. DAMA systems assign communication channels or circuits based on requests issued from user terminals to a network control system. When the circuit is no longer in use, the channels are then returned to the central pool for reuse by others. The same capabilities can be used to dynamically control and groom individual base station traffic on a call-by-call basis. This technology is particularly suitable for situations in which many remote base stations (e.g., 100) each handle only limited traffic (e.g., less than 2 Mbps), as is often the case in rural and low density areas. A high level DVB-RCS network architecture is shown in Figure 7.7. In its basic form, DVB-RCS provides "hub-spoke" connectivity; i.e., all user terminals are connected to a central hub that both controls the system and acts as a traffic gateway between the users and the wider Internet. The user terminal consists of a small indoor unit, and an outdoor unit with an antenna size not much bigger than a conventional direct-to-home TV receiver. The outdoor unit connects to the RCS terminal which communicates with the hubs via satellite. The DVB-S2 (Digital Video Broadcast - Satellite Second Generation) also provides an option for low traffic carrying sites and is capable of handling voice or mixed voice and data se