Retail Wi-Fi: Predictive Modelling
Once you have clear design requirements and know which AP you will be deploying make sure you use a professional software package such as Ekahau Site Survey Pro to create a predictive model. This involves building a mathematical model of the building by loading in a floor plan, and drawing in the exterior and interior walls, windows and doors. You need to specify what they are made of so that the unique attenuation and reflectivity characteristics of the materials can be accounted for by the software. If a CAD drawing is available, the whole process becomes much easier because Ekahau Site Survey Pro will automatically draw the walls for you.
Once you have completed drawing the walls you must then enter the performance and capacity requirements of the network. You can now place your access points (Ekahau Site Survey Pro has a library of the antenna patterns for most common AP vendors and models) onto the floor plan in order to see how the signal will propagate and self-interfere. You can freely move APs around and change their individual channel and transmit power settings to see how it impacts the performance of the network. You can also get Ekahau Site Survey to automatically place the APs and optimise the channel plan to minimize co-channel interference based upon the performance and capacity requirements you entered.
The main advantage of predictive modelling is that it’s fairly straightforward and inexpensive to do and doesn’t require a site visit. The down-side is that it uses simplified assumptions, so if the floor plan is inaccurate, or the actual building materials behave differently in the real world, the resulting design will be incorrect. However, we still recommend them because they are extremely useful when creating an initial estimate on the quantity, location, and channel and transmit power settings of your APs.