Deploying a wireless network consists of two aspects- Coverage and Capacity planning. In this blog we are going to discuss Coverage Planning. Whether it is deploying a new wireless network or it is refreshing an existing wireless network the primary question is ‘how many APs should I deploy?’ Lets understand how we can address this question by answering the following questions-
- What is coverage planning?
- Why is coverage planning necessary?
- How to ensure coverage?
What is coverage planning?
When deploying a wireless network or planning for wireless refresh one of the primary steps is to plan for coverage planning which essentially means ‘How to ensure wireless service throughout the campus area?’
Why is coverage planning necessary?
We need coverage planning to address the following-
- All the client devices are wireless, we rarely have any wired devices in our environments.
- These wireless devices often roam in the environment so it is essential that they don’t lose wireless connectivity while they roam and there is no service degradation while they do so.
- Our environments have dry walls, metal racks which cause reflection, refraction, absorption of the wireless signals.
- Our environments are dynamic- High ceilings in warehouses, open stadiums, Low ceilings in schools and offices. The AP mounting location and elevation impacts the wireless signal pattern and coverage area.
- Our environments have varied client devices- low power devices like phones, scanners and high power devices like PCs. The planning should ensure wireless signal from the APs provides sufficient wireless signal to all the devices.
- AP and antenna types- AP coverage areas and antenna patterns vary based on the type of APs and antennas used in the deployment.
How to ensure coverage?
Predective RF design– I highly recommend using a predective RF design tool like Ekahau to determine the number of APs and their mounting locations required in your environment. This tool requires you to upload your scaled floor plan and allows you to choose the AP type that you plan to deploy. Based on the dimensions, wall types and ceiling heights defined, the tool provides an approximate RF pattern that the APs will generate when deployed. This method can be used to determine the number of APs needed in the environment to provide optimum coverage. The RF design strategy is usually sufficient to plan AP count and location in ‘not so complex’ RF environments like office spaces or schools but are not sufficient when it comes to complex RF environments like warehouses for which I suggest conducting an RF survey/AP on stick.
Passive RF site survey– This method comes in handy if there is an existing network and you are expected to leverage the existing AP locations. Passive site survey using Ekahau can be used to determine the existing wireless network, AP locations, WLANs being broadcasted and the RF patterns the existing deployment is generating. This method can be used to modify the existing environment, add/remove APs as per requirement or adjust power levels to control service areas.
AP on a stick- This method comes in handy when there is a fresh deployment. I suggest performing a predective RF design to determine approximate AP locations and then performing AP on a stick and determine the coverage pattern by placing the AP at the locations determine from the RF design.
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