Building-to-building Design
Design examples

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.