When conducting a site survey, several paramount factors that may affect the performance of the WLAN must be thoroughly considered.
If we are going to install the WLAN in a building, we should know whether they are many walls or large structures or any types of obstacles to block the RF signal. Where will the network to be installed, in an open environment or closed environment such as building or office. Some environments that contain certain object such as large filing cabinets, concrete pillars, steel beams and even heavy machinery may reduce the range of wireless access points. The amount of RF interference (RFI) and electromagnetic interference (EMI) are actually present and paramount. Some environments that include cordless phones, electronic devices, microwave ovens could degrade WLAN performance must also be considered.
Identifying AP locations and the antennas to be used is very important in a site survey. To provide seamless Radio Frequency (RF) coverage for WLAN, APs must be positioned with wide enough overlapping coverage to ensure there are no gaps, or dead spots within the coverage area. We must also identify the areas where additional APs, antennas or repeaters may be needed to overcome interferences, signal loss or range problems.
RF signals transmit and broadcast through the air are subject to attenuation, signal strength loses while encountering obstacles. The distance between the AP and client affects WLAN bandwidth and therefore capacity. The distance between client’s device and AP increases, the signal strength will then decrease. In this case, the bandwidth has to decrease to maintain the connection. The channel assignments for APs will need to be far enough apart to avoid inter-access point interference.
We cannot determine exactly the overall effect of all the objects in most sites if we do not do the testing and verification as the actual attenuation will vary widely.