Last updated on July 26th, 2020
WiFi site survey is recommended for companies facing issues with their WLAN. But what exactly is a WiFi site survey ?! What information does it generate? And do you really need to do commission one for your organization ?
WiFi site survey is a type of RF site survey. A WiFi site survey software tool loaded to a mobile computing device like a laptop or mobile phones or tablet helps to conduct the survey. The analysis of transmission of wireless signals in the WiFi frequencies of 2.4 GHz and 5 GHz is the main purpose of a WiFi site survey .
Invisible Medium of Transmission
In case of a wired LAN, the data travels inside cables from client device to the internal switches. The transmission losses in data cables are almost negligible and full rated speed of cables can be mostly realized. The transmission in one cable does not realistically affect transmissions in other cables.
WiFi devices operate using radio signals in the frequencies surrounding 2.4 GHz and 5 GHz. The transmission of information from and to client devices happen completely in the air medium, through open spaces inside and outside the office environment.
As there is no fixed pathway between clients and wireless Access Points, the transmission of data becomes very complicated. The success of information transaction starts depending on various factors unrelated to network hardware. WLANs from neighbors, microwaves ovens, cordless phones, wireless CCTVs, rogue access points, construction materials etc affect data transmission.
Such kind of influences from non-network sources are invisible to our naked eye. In fact the transmission and progression of signals from one’s own WLAN is invisible. It will be difficult to manage something that cannot be seen and measured.
Usefulness of WiFi Site Survey
Tools like WiFi site survey software and WiFi spectrum analyzer can capture these invisible signals for analysis and further management. WiFi site survey can generate a WiFi heat map. Spectrum analyzer can plot signals from non-802.11 sources using specialized hardware and software.
Understanding Interference from a WiFi Heat Map
WiFi site survey generates a WiFi heat map. It helps to visualize the 802.11 signals present in the area of survey. The WiFi site survey software tool integrates with external or internal WLAN adapters in the laptop/mobile phone for the survey. During the survey, the software tool captures all available 802.11 WLAN signals in the area and identifies and color codes each signal.
The color codes are given as per RSSI (Received Signal Strength Indicator) values in the survey device. The color scale used for plotting the WiFi heat map is usually provided in the generated heat map.
Let us take the below sample customer WiFi heat map in Fig.1 to understand it further:
As seen, the colors vary from deep red to orange, yellow, green, blue and white. The corresponding RSSI numbers are varying from around -35 dBm to -90 dBm and above. the strongest signals represented by red color are around -35 dBm in strength and are the areas where interference is the highest. These places most probably have the interference sources- rogue access points in this case.
This map gives a fair idea of the amount of 802.11 interference spread in this place. Armed with such WiFi heat map, one can go around the office to physically check and remove the WiFi interference coming from other 802.11 WiFi sources. Without this WiFi heat map, it would have been difficult to appreciate the severity of interference in this particular case.
WiFi interference is one of the major causes of WiFi connectivity issues and a WiFi site survey using WiFi spectrum analyzer tools helps to find and mitigate it. There could be many other reasons for poor WiFi performance like noise coming from non 802.11 sources like microwave ovens from the pantry, cordless phones etc. It is important to find and mitigate them with spectrum analyzer surveys. Wrong configuration of wireless controller and access points may also cause issues. A configuration audit will reveal the same.
Using a WiFi heat map to understand signal dead spots
WiFi heat map reveals signal dead spots in the office area as well. Lets look at the below sample map in Fig.2 for reference.
As seen in the map above, there are many white spots appearing right inside the office area. These are the spots where WiFi signals from the WLAN are not above the acceptable limits for data transmissions. The users sitting inside these signal dark spots will have either have difficulty in connecting to the WLAN or have a very slow network through a weak connectivity.
The above information gathering is possible only through a WiFi site survey and this further reiterates the importance it.
If you are facing persistent connectivity issues in your office, you NEED to get a professional WiFi Site Survey done as the first of many probable steps to fix WiFi network issues and optimize WLAN.