The site-to-site design example in Figure
is for a
point-to-point connection requiring a bridge link across a freeway. The
required distance is only half 0.8 km (0.5 mile). Therefore, the antennas need
to be mounted at 3.9 m (13 ft). Assuming that the antennas are mounted on the
roofs of the buildings, this is not a problem because the buildings exceed the
minimum height. The cabling from the bridge to the antenna is 6.09 m (20 ft) in
Building A and 15.24 m (50 ft) in Building B. This does not have an impact,
because the distance is so short. In this case, use patch antennas so that the
beam can be kept focused and not be concerned with interference from other
companies.
The design example in Figure
is a
rural area that requires a distance of 40 km (25 miles). Because of the long
distance, parabolic dishes were chosen and cable lengths were kept to a
minimum. A rate of 11 Mbps will be impossible because of the distance, so a
2-Mbps rate will be used. This configuration is well within the necessary
specifications. Even though it is possible to reach a distance of 81.6 km (58
miles) at 2 Mbps, please note that line of sight over 40 km (25 miles) is hard
to align and therefore is not recommended.
The design example in Figure
shows a
metropolitan area that leverages a point-to-multipoint implementation. The omni
antenna poses a potential problem of interference with other WLAN customers
using the same channels, but it is reasonable to think that no interference
exists.
The design sample in Figure
shows a
headquarters building within a metropolitan area where three separate
point-to-point links have been implemented. Such a configuration could be
required because of interference from other companies using WLANs. This is
instead of simply using a point-to-multipoint design. In addition, the
buildings will receive greater bandwidth in this configuration than they would
using point-to-multipoint. This is because there is no shared bandwidth in this
design. Antenna mounting is not a concern because of the short distance and
already tall buildings.