Wireless Broadband Networks
you need a piece of equipment (CPE – see definition later) in each
building where you want to connect two LAN segments. For those situations,
where a clear line of sight is not available, one or multiple hubs may be
deployed – acting as repeaters and logical diverters of radio signals. The
Customer Premise Equipment (CPE) in most implementations consists of two
fundamental components: a Network Interface Unit (NIU) - an indoor unit
providing circuit emulation and Ethernet data services – essentially a
Transceiver and an antenna unit mounted on the top or side of the building.
In some cases, the transceiver and antenna are integrated into one unit –
e.g. in Nortel’s Reunion Broadband Wireless Access products. NIU is
connected to the data network (typically a LAN) in the two buildings.
Where multiple services (voice and data are
employed), there is another piece of equipment that is called Base station
equipment – that provides multiplexing and channel separation.
In those cases where a clear line of site is
not available between to points or where multiple locations need to be
served, there is a Hub in the center as shown in the following schematic.
Differences in data transfer between
components reveal some of the benefits of a wireless system as opposed to
other technical alternatives like cable and Digital Subscriber Line (DSL),
or traditional ISDN. Whereas
cable and DSL utilize Frequency Division Duplexing (FDD), Wireless is able
to support all applications while offering the entire bandwidth for
balancing upstream and downstream packet traffic.
Wireless does this by utilizing Time Division Multiplexing
technology, recently advocated by the Universal Wireless Communication
Consortium as the benchmark for Wireless Broadband technology.
The difference is, is that FDD requires allocations of upstream and
downstream traffic meaning they are asymmetric, and are unable to support
bandwidth-hungry 2nd generation applications such as Video Conferencing,
Multimedia Email, Interactive Gaming, Online Banking, and other applications
on the horizon for business and residence alike.