How to Conduct a Wireless Site Survey
A network project normally start with a plan. For wireless network project, a plan typically start with having a design and a heatmap for you to pin point exactly the best position you want to place your access points.
In a small scale wireless project its easy and safe to assume AP placement and estimate the spot wherein wireless signal can cover most area and serve wireless users. This can be applicable to small offices like retail stores, branch sites and SMB startups.
For mid size to large scale organizations that requires wireless solution, it can be more complex. Design would need consideration and factors such as wall material, establishment interior architecture, number of users and wireless devices. This type of wireless deplyment may be for bigger offices, Universities, hospitals, warehouses and airport terminals among other possible samples
We need a well prepared heatmap to assure a more smooth project implementation. A wireless deployment normally need to tap cabling works who would run connectivity from the switches to the access points. We need to be precise on the location prior to setting up your cables. Wrong AP assignment and relocation would also result to re doing cabling all over again which includes drilling holes and pulling cable over the ceilings and walls again. Number of switch port allocation and PoE budget needs to be prepared for each access points or nearby power outlet if PoE switches or injector are not an option.
What does a wireless heatmap looks like
A wireless heat map is also a floor layout similar to what you see on other construction projects. You will see how the building looks like from top view with walls, doors, windows and hallways that is measured by dimensions as well.
On a heatmap drawing you will normally place the position of the wireless access points on a certain position in the floor layout to indicate where you want to install them during the actual implementation. Aside from the AP position each access points can be presented with a simulated wireless signal coverage measured by estimated signal strength metric in -dbm (decibels).
What type of tools needed to prepare a wireless heatmap
Heatmap typically starts with a site survey of the location where you intended to implement your wireless project. Details gathered from the site survey are then load to tools to help you generate your wireless heatmap design. So what do you typically needed to complete this process?
- Floor layout – you will need a well-drawn floor plan layout so that you have good visual of the entire areas to be covered by the wireless signal. A good layout includes updated setup of the current vicinity and best included with dimensions for proper measurements. You may usual request a copy of this drawing from a building administrator
- Wireless Access Point – The access point will simulate the actual wireless coverage and strength of your wireless coverage once the actual access points are installed. This will generate signal to on a particular area on your layout. Since this AP would play the simulation wireless coverage it would best to use a model of the actual wireless access point you plan to purchase or install. Different access points differ in signal straight and coverage base on the specification of their antenna hence each access points may provide you a different data on your site surveys. On most cases including an access point on your site survey is a best way to generate simulation, on some instances a survey may go without an access point if accuracy are not much of concern.
- Heatmap tool – To present the data visually, heatmap is generated by computer aided design application. This tool normally require a floor plan to be loaded in it and added inputs from the site survey for it to simulate the output of your wireless design. There are many heatmap tools that can be downloaded. Some may be free applications while there are also paid version. There are also some heatmap tools that are available as part of a feature of some brand’s wireless system like on some wireless management or BYOD system of Cisco Meraki dashboard and HPe Aruba Airwave.
Conduct a site survey for a wireless project preparation.
Once you have all tools prepared let start with the actual site survey. The objective of the site survey is to identify and generate a simulation or an estimate of your wireless coverage you want to implement. By this you can plan the location of the access points, placing them on the most strategic location where in each wireless access points can reach more areas, people and devices.
During a site survey it be wise to understand the situation during the actual day to day operations of the wireless user in that certain areas, as well as how certain structure on that area may affect the strength of the wireless signal.
Number of concurrent users and devices
Take note of the usual average users count on a certain area. A wireless user in today’s standard most of the time have at least two or more device. User may have both his laptop, smartphone, tablet or other smart device and accessories connected to the wireless network at the same time due to the evolution into IoT( Internet-of-things). In ratio, it be safe to assume a 1:3 user to devices ratio.
This information you will need to validate so to have a understanding of how clustered together the device on this area is going to be. With this in mind you may estimate an appropriate AP model and sufficient AP quantity to address the demand of wireless loads. Think about stadiums, airports, food court and convention.
Wireless network Use Case scenario solutions
Aside from counting the users and devices, we also take note of the reason why we are considering implementing wireless solution. Not all environment are the same, though common wireless setup such as corporate offices can be typical on most cases.
Other use case for wireless setup can be on a warehouses where users normally roam around and scan an item using a wireless barcode scanner to be transmitted barcodes wirelessly to the network database for inventory.
Outdoor, where aside from being ruggedize, wireless access points may need to broadcast signal to cover a huge areas like parks and fields. Concentration of wireless signal is possible by utilizing sector antennas. There are also application for wireless bridge to connect distant locations through wireless radio where in cable may not be possible.
Just remember that the objective of the site survey and the heatmap design is more than just to pin point AP location but also to provide wireless solution to a use-case scenario.
Materials of walls, objects and other obstruction
While you examine the vicinity one thing to check are the materials that makes up the interior of the building, like walls, doors and other physical objective that can block your wireless signal coming from the access points.
Materials such as concrete and metals can reduce a large amount of wireless strength as the signal travel in it which more or less can be about 12db.
Material like dry wall, glass or body of water can also affect and weaken the signal as it pass through this objects. Though this materials can be less resistance to wireless frequency and allows more wireless to pass through it compare to the metal and concrete. Aside from the materials, the thickness and height of thus objects must also be considered as the thicker it gets the more resistance it becomes same as the height as it block more open spaces.
Signal strength and signal Interference
The purpose of having a wireless access point during a site survey is that you could actually test the signal strength of the wireless coming from a certain spot up to a certain distance. Since the Wi-Fi signal are real you can also test signal strength with the consideration of different objects and materials which the Wi-Fi signal travels into.
While the access points emit the wireless signal, the heatmap tool or analyzer can capture the signal status on the other end. This tools can generate report of wireless strength measured by -dbm (decibels) metric where in the number nearest to zero is stronger. I personally recommended the measurement -65dbi as the the boundary set for the good wireless range during site survey. Outside this range or higher -dbm reading can mean slower and weaker wireless signal thought you may still be able to connect to it.
physical objects obviously can weaken and limits the strength and range of the wireless signal, but undetected to an naked eye other factors that can also affect wireless strength such as conflicting wireless signals coming from nearby device that omit same frequency range as your wireless AP. This can be appliance or other tenant’s access points as well. Our wireless signal use the free frequency under the 2.4hz or 5ghz with various channels in that range. If you’re heatmap tool capture this signals you may decide to ether remove the conflicting device or its frequency, if not possible then you may do the adjustments on your end and assign a certain none conflicting channel on your AP intended.
As a added note, controller base access points typical have this features of automatically adjusting the best available channels, This may be good as long as there are still available channels to use. While the 2.4 ghz can easily be populated due to limited number of channel selection, you may consider shifting to 5ghz for more channels options especially today with the new wireless protocol “802.11AC wave 2”.
Access points mounting spot
By now you must had gathered a good amount of data from your tools. Last thing to consider now is the exact location to mount your access point. By this consider the ceiling height, the cabling distance needed to reach the AP from the switch, and the power source for the AP.
Most access points now are PoE ready so long as you have a PoE switch, if none then a nearby power outlet must be provision for the access points.
Consider also the height of the ceiling, generally it is always best to mount the access points on the ceiling but mounting it way to high can make it less effective as it distance away from the wireless devices accessing it.
After the wireless site survey
The objective of the site survey for your wireless project is to prepare the team for the actual wireless project implementation. By now you should have a properly gathering all data and took note of all the consideration. You have the floor plan plot with access points locations and expected wireless strength measurements for each areas. You may use this data to estimate the quantity of access points you will need for your project. Most wireless vendors typically conduct there own site survey to present a heatmap to there customers, it be best that you know as well how and understand how they are able to come up with the proposal for proper collaboration.