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| Design Methodology | Specialist Equipment | Bespoke Reports |
Designed in Partnership with the Customer
We view the design process as a partnership. We prefer to adhere to best practice in our Wi-Fi designs (see some of our Technical Design Articles for examples), but for practical or economic reasons, you may not be able to adhere to them. For instance, it may not be possible to install APs in their ideal locations, facing down from the centre of ceilings, because of physical cabling or security restrictions. If this is the case, we will explain the implications. For example placing a line of APs in corridors will cause interference problems that can severely impact the performance/capacity of your Wi-Fi. We can assess your current cabling/routes and discuss possible cabling strategies, or alternative remediation strategies such as the use of specialist antennas, or base a design on limiting the Wi-Fi to 20Mhz-wide 5GHz band channels. We can then put a design together, based on the agreed criteria for performance/capacity.
Designed to Incorporate Client Device Behaviour
Client devices have their own Wi-Fi behaviour and requirements which will affect the cell size and other aspects of configuration, they also limit the performance of your Wi-Fi (see How Client Devices Limit Your Wi-Fi Performance for some examples) which defines its capacity. We take into account the behaviour and performance requirements of your preferred client devices. We would ideally profile their Wi-Fi behaviour before the design of your Wi-Fi begins. For example, a device may only operate on a certain Wi-Fi band, it may only support a sub-set of the Wi-Fi channels available in the UK, and it may only implement certain clauses within the Wi-Fi standards, so these limitations would need to be supported. Then within these constraints we would determine the optimum configuration of the Wi-Fi required for performance and roaming.
Built for the Intended Applications
Different applications put different demands on Wi-Fi designs, you may only be using a data service at the moment, but you may need to migrate to a voice or video service or a Real-Time Location Service in the future. An understanding of any specific applications that the Wi-Fi will be required to deliver is therefore essential to the design process.
Further information about some specific application design criteria will be added to our articles Designing for Voice and Designing for Location Services.
Meaningful Criteria for Design and Reporting
One of the outputs of a Wi-Fi site survey is a heat map. Heat maps show various Wi-Fi quality measures such as signal strength, which are colour coded on the map. But a heat map showing the received signal strength from an AP is misleading, and one could argue is also meaningless, unless the AP has first been configured to meet the design requirements of client devices and the overall performance/capacity requirements of the network. An AP may be set to a high power, and it may produce an excellent heat map, but this will not represent the experience of client devices as we explain in our article Signal Strength MUST Be tuned! That is why we focus on these design elements first, to arrive at a meaningful criteria that we can then design for and measure against in our design reports. The heat maps we report will then show the performance of the Wi-Fi when all components are configured to their designed criteria, and also show how much tolerance has been factored into the design to cope with varying RF conditions/behaviour. It is important to allow tolerance in the design as we explain in our article Tolerances Required for Polarisation and Other Effects, so this will also be part of our agreed criteria.
It is recommended that any Wi-Fi design is based on on-site survey measurements.
Our on-site surveys include a look at the overall RF spectrum, which can identify practical sources of interference that have implications for the Wi-Fi design. Lots of devices now transmit on the Wi-Fi bands because they are public bands. Even automated lighting uses radio beams to detect motion, and this can interfere with your Wi-Fi. There may also be other Wi-Fi devices in the area which would interfere with your Wi-Fi. These observations will only be picked up from a site survey.
Our surveys also take measurements of the building characteristics and their effects on any Wi-Fi design. Every building is different and the way a building, or even a single wall, affects Wi-Fi often varies because of what is hidden within the construction of the building and how that effects radio waves. There is no way to know for sure what these effects are unless measurements are taken on site. Furthermore, the more common Wi-Fi planning tools used in the industry only model signal losses through walls. It is not just distances and losses that account for the strength of a signal, because reflections can also cause significant peaks and troughs where signals overlap. Measurements are required to properly quantify these effects.
Also, because of these effects, AP cells do not form neat circles, an so on-site measurements are essential to find the best AP locations and configuration to build an effective Wi-Fi design. We use multiple APs during our site surveys to reduce the overall survey time. This allows us to test alternative AP positions effectively. It also allows us to test the full extent of several AP cells at a time, and as Wi-Fi signals extend quite a way (measured to about -85dBm depending on the standard) it allows us to save time whilst taking extensive measurements. This ensures that our heatmaps show the full extent of the signal of APs in our design, and not just the local signal, which provides an accurate picture of channel overlap/interference to validate our design. Using multiple APs also allows us to undertake some simple throughput and roaming tests, to ensure that the client devices will work as expected with the Wi-Fi when deployed.
After investing in a quality Wi-Fi design, it makes sense to perform a quick survey once the new Wi-Fi network has been installed, to make sure that it has been installed and configured as it was originally designed, and that the design is working as expected, and this can include some performance tests.
Since it is the client experience that defines the effectiveness of the Wi-Fi network, we can also go a step further. We can optionally provide temporary licenses for a professional application that you can load onto your devices which will test and monitor the Wi-Fi experience. This will highlight any hidden problems that need to be resolved.
Click on this link to find out more about our Client Device Performance App
Should any issues be found then we can perform rudimentary analysis and diagnostics using a Handheld Diagnostic Tester, or we can do detailed diagnostic work using a Protocol Analyser.
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