A site survey may involve completing both an active survey and/or a passive survey.
During a passive survey, RF data is collected from access points and other wireless devices
in the area. This information enables the surveyor to understand the existing RF environment
and other RF parameters. It highlights potential sources of interference and other variables
that may need to be considered when deploying a wireless network. Data captured may be
from neighbouring networks that are not under the administrative control of the client.
The passive survey requires an engineer, equipped with a specialist survey application, to
walk around the site whilst capturing non-intrusive RF data. In its passive mode, the tool does
not initiate any RF traffic to understand RF behaviour. Instead, it listens to traffic that the client
adapter hears and displays the results.
An active survey involves associating to an existing wi-fi network on site or placing a survey access point in an appropriate position as determined by the surveying engineer to test the desired coverage area.
A survey tool is used to associate to the access point and then RF data is captured and recorded to identify the performance of existing networks or to determine the optimum placement for new access points for coverage, throughput and utilisation. Using a survey access point is the default method for determining access point placement for a new wireless LAN infrastructure.
On larger projects where clients have multiple sites of similar size and layout a predictive
desktop survey may be a cost effective solution. During the predictive desktop survey a
specialist survey application is used to model the RF characteristics.
Point to Point and Point to Multi-Point Surveys
The survey often includes some, or all of the following:
Key infrastructure such as buildings and existing radio masts, which could be utilised to achieve clear line of sight for radio transmission
The availability of clear radio line of sight from each node to an identified location or hub
Local radio spectrum analysis to identify any existing radio transmissions that may affect the viability and performance of the proposed wireless network
The use of MEWP's where necessary to establish availability or radio line of sight between identified points
The use of laser height measurements of buildings and other obstacles that might impinge on the Fresnel zones associated with each proposed wireless path
Specific design challenges, especially those concerning the availability of radio line of site for each part of the network