The Unlicensed National Information Infrastructure (U-NII) is a viable spectrum that can offer commercial results. Here are two examples:
In a university campus environment there are a number of distributed buildings from the main information technology (IT) center. In order to provide high-speed broadband service, a grouping of access points (AP), each having six sectors (360 degrees of coverage each), are installed on the rooftop. In the IT center a patch panel is used to connect to the anchor switch, which multiplexes the traffic over an OC-3 to the ATM network.
One control server sitting in the IT center has enough capacity to manage all the APs and subscriber units over two connections between itself and the anchor switch. One is an ATM25 connection to carry the PVCs, which connect the control server to the APs and SUs as well as the TCP/IP connection to the element management system. The second is a 10/100 Base T Ethernet connection to manage the anchor switch.
That configuration supports long-of-sight to six buildings on campus, providing 20 Mbits/second per sector of broadband coverage for engineering, administration and research, and Internet access from student rooms.
Recently, a digital subscriber line (DSL) service provider discontinued service, leaving its customers without high-speed Internet access. A fixed wireless service provider quickly supplied service by adding sectors to already installed APs, and installing SUs on the customer's buildings. To attach the customer's equipment, the DSL modem was replaced by an inexpensive 10 Base T Ethernet hub connecting to the local-area network already existing at the business.
At the basestation, the additional APs were connected to an Ethernet switch. To accommodate that traffic to the Internet, another router was required. The protocol supported by this architecture is RFC1483 bridging.