A site survey is required for proper implementation of a wireless network. No one can tell exactly how wireless equipment will operate in every circumstance without a survey. This includes both in-building wireless LANs and bridges between buildings.
This is especially true within a building where there are hidden obstacles in the walls / Racking or other existing wireless applications, and is equally true for outdoor wireless links where obstacles such as trees and power lines are involved.
Wireless surveys analyze the conditions required to provide an optimal radio link. The complexity of the survey depends on the nature and details of the proposed network. These details include the physical area of the network, factors within the building, and for outdoor bridges the number of sites involved, the terrain and the distance between sites.