Wireless Site Survey? Wireless site survey should be the first step in deployment any new wireless network.
Wireless Site Survey
Wireless site survey, sometimes called an RF site survey, is the process of planning and designing a wireless network.
Types of Site Surveys
There are three types of wireless site survey:
Passive site surveys are performed without connecting to the access point or wireless router. The result is the most often:
- Initial site surveys
- Validate the final RF settings
- Identify the rogue access points
- Locate the locations with the possible RF problems.
In the active wireless site surveys you need to connect to the access point. The active wireless site surveys can be performed in two ways:
- BSSID – Basic Service Set Identifier Method
- SSID – Service Set Identifier Method.
In the BSSID method client is locked only to one AP (AP prevents that client from roaming).
In SSID method client associates to the one SSID and then it roams between different APs. The method is usually used for survey of multiple APs and is done after deployment.
In the predictive survey the model of the RF environment is created by the simulator software. It is very important to enter the correct data to the simulator software like the location and RF characteristics of the site obstacles.
To collect this information you need to place the temporary access points and collect information on the signal propagation in the environment.
Site survey software applications have option to collect the RF spectrum information with the hardware spectrum analyzers. The analyzer collects information from other wireless signals, like microwave ovens, cordless phones and Bluetooth, that will cause the interference.
Predictive survey is performed in the following situations:
- Before deployment
- To get data for needed WiFi devices
- In less demanding roaming requirements
The Site Survey Process
The process of the wireless site survey consists of these steps:
- Getting the exact requirements
- Getting the proper maps
- Visual inspection
- Evaluation of the existing network infrastructure
- Identify the coverage areas
- Choose the preliminary locations for the access points.
- Verification of the access point locations.
- Document the APs locations
Getting the Exact Wireless Requirements
To be able to identify the optimum number and locations for the access points, you must have a real understanding of the different requirements for that particular site:
- The primary requirements
- Type of the traffic (voice, data, video..)
- Type of the facility
- Type of the wireless clients
- The Customer facility requirements
- Single floor/multi-floor
- The wireless clients requirements
- Minimum RSSI – Receiver Signal Strength Indicator
- Minimum SNR – Signal to Noise Ratio
- Delay and Jitter
- Maximum transmit power (Tx)
Getting the Maps
Collect the maps and blueprints of the site location. If you can’t get them, you will need to make them by yourself. The diagrams should have exact locations of walls, corridors, floors… Wireless site survey applications have option to import the maps.
The next step in the wireless site survey is a visual inspection of the facility. Note any obstacles that have an impact on the WiFi signals (metal racks and partitions or any other barriers that are not located on the maps). Also note the possible best locations for placing the access points like ceiling tiles or pillars.
Evaluation of the Existing Network Infrastructure
Evaluate capacity of the existing wired networks – the backbone in which the access points will connect. This includes:
- Number of Ethernet switches
- Number and type of free ports on the switches (electrical, optical, PoE – power over Ethernet).
- Type and number of routers
- Data rate capacity of the routers
Identify the Coverage Areas
Note on the map all areas that need to have the WiFi signal. Also, you need to identify the places where the wireless coverage is not needed and also where you need to avoid the wireless coverage. The best way is to cover the site with the least number of access points, because the cost will be lower.
Choose the Preliminary Locations for the Access Points
Consider the best locations for placing the APs. Plan the overlapping between the APs – usually the best option is to have 25% of overlapping among adjacent APs. Keep in mind the channels of adjacent access points need to be far enough (the best is 5 channel difference).
Also, do not forget the mounting locations for the APs like and place for the UTP cables for the access points.
Verification of the AP Locations
After placing all the access points in preliminary locations, you need to perform the wireless site survey testing. Applications for the site survey have option to identify:
- Location of APs
- Data rates
- Signal strengths
- Signal quality
Monitor the readings in wireless site survey application and cover all needed locations. Consider the minimum needed SNR and the signal strength.
Based on all these results, reconsider the locations for the APs.
Document the AP locations
When you have optimal positions for all the APs, document them on the map. This is the last but also very important step in the wireless site survey.
Wireless Site Survey – The Final Notes
Wireless site survey is the procedure for professional deployment of the wireless networks for large areas and lot of access points. If you are interested to find out more about the wireless site survey, I recommend that you check the article Site Survey Guidelines for WLAN Deployment.
Read the article about the WiFi extenders and how increase the coverage and range of the WiFi network on WiFi Extender – The Best Way to Improve the Range and Coverage of your WiFi Network.