User's Manual

SPEEDLAN 9000 Series Installation and Operation User Guide Version 3.03
Introduction 1-13
Broadband Backbone Links
The two-high speed microwave links (50 to 155 Mb/s) provide full-duplex broadband
backbone links to other areas of the MAN. These microwave links provide the
necessary bandwidth for network expansion and eliminate bottlenecks. Service
providers can save money because they will no longer have to depend on backhaul
support from the wired telecommunications infrastructures. The three polling base
stations (represented by red-dashed links) create a broadband wireless MAN, while
operating independently from the telecommunications infrastructure. The three base
stations have been installed on three non-overlapping 2.4 GHz channels, providing 11
Mb/s of connectivity to three sectors of the network. This effectively gives the ISP base
station (e.g., about a 33 Mb/s if using a 100 Mb/s backbone) from which to increase
the network penetration and user density. Each remote base station would use
directional antennas to achieve maximum distance and to prevent interference from the
other base stations. These sectorized base stations then connect to other SPEEDLAN
9000 products, which are located in mesh clouds throughout the sectors. (In Figure 1-
6 on page 1-12, the mesh clouds are represented inside the yellow circles; the mesh
routers in the cloud are represented with blue-dashed links.) As a provider's network
grows, connections may be expanded incrementally to create entire wireless
metropolitan area networks.