Information Technology Reference
In-Depth Information
Access Point
FIGURE 13.7A
One of the three basic types of wireless links: (a) indoor point-to-multipoint.
Outdoor Point-to-Point Links
An outdoor point-to-point connection is typically made to connect two buildings,
each with an internal wired network (Fig. 13.7b). The main differences from the
indoor network are that the APs must use special bridging software, and that weath-
erproof outdoor directional antennas are connected via an appropriate length of RF
cable to the indoor-mounted AP. The server is then connected to the wired LAN,
and the bridge is complete.
The operation is somewhat more complex than the classic wireless LAN,
because each building may have an extensive wired LAN, and the appropriate
bridge tables must be constructed by either wireless server/bridge. A router function
could also be employed, which would allow the buildings to have separate network
addressed (IP subnets, or IPX network numbers). Bridges intended for outdoor
point-to-point operation require special software on the AP.
Outdoor point-to-point bridging can span distances of up to 20 km, if there is
clear line of sight and high-gain directional antennas are used. However, it is some-
times possible to bounce signals off buildings and other structures. Other consider-
ations are the provision of very low loss RF cable to the antennas and lightning
protection for the outdoor structures.
