Wi-Fi Pre-Deployment Surveys (also known as AP-on-a-stick surveys) are an integral part of the process of undertaking a wireless design that actually works.
At IPTel we recommend a three stage approach to wireless RF design.
Starting with the Predictive RF Survey, and following with the Pre-Deployment survey, this allows the design to be built, tested and refined before the Access Points are actually installed.
The third and final stage is the Wi-Fi Deployment Validation Survey.
Wi-Fi Pre-Deployment Surveys: Background
First up though, a little background as to how a Pre-deployment survey fits into the process of Wi-Fi design.
Wi-Fi is a great technology that we all know and love - and use extensively.
We've all also experienced poor Wi-Fi - you can't connect, it keeps dropping out and its slow.
Wi-Fi can be designed to be very reliable, but it needs a Wi-Fi Predictive Design to ensure its been designed to support the end devices and the environment in which it will be installed.
The initial Wi-Fi design is conducted using simulation software and then this design is refined using the Wi-Fi Pre-deployment survey.
At this stage, the design is tested onsite and the design can be refined based upon real-world data.
This can save a huge amount of time as the access points can be installed in the designed locations, with certainty they will work.
Why undertake a Pre-Deployment Survey?
If you've been suffering with poor performing wireless that gives you low speeds or drops out, then you'll already recognise why you'd want to design correctly in the first place.
For those out there thinking that just a predictive will do, you might reconsider - undertaking a Wi-Fi Pre-deployment survey is a whole lot cheaper than trying to remediate an install once its been done (we get called into quite a lot of sites which haven't been designed properly - if you need help, drop us a line!).
The Wi-Fi Pre-deployment survey follows the Wi-Fi Predictive Design and allows us to come out to site and see what is actually there. We've seen buildings from standard drywall through to 30cm thick brick - and it makes a huge difference in RF terms.
There's a bit more on the overall process on our main website, detailing how wireless surveys are the best way to achieve a quality outcome for your new wireless installation.
Wi-Fi Survey Types
Let's take a quick look at how wireless surveys fit together. There are a number of survey types, which all have different roles to play. For the most part, any type of wireless LAN design uses both the Wi-Fi Predictive Design and the Wi-Fi Pre-Deployment Surveys phases as a combined pair to design, test and then improve the original design.
The three stages approach we use is outlined below:
|Wi-Fi Predictive Design||
This is the initial survey, performed offsite. RF design software is used to model each floor of the building with provided floorplans, which are adapted to reflect the physical environment(e.g. internal walls, x-ray rooms).
The survey may be undertaken to data, voice or location grades.
|Wi-Fi Pre-Deployment Survey||
This survey is performed onsite, and is to be conducted before cabling and access points are installed.
The results are used to identify any variation with the predictive survey output.
|Wi-Fi Deployment Validation Survey||
Once the network has been commissioned, a final 100% walk around survey is conducted.
There's one more survey type to be aware of - the Wi-Fi Diagnostic Survey.
Once your survey is complete, you will move on to the network design phase (depending if you're in classic or SDA design mode).
Of note is that Wi-Fi that works well is built from a number of good layers in the design process. This means that the RF designs are one aspect, but you need to conduct post installation checks, tuning and updates, to ensure you have a reliable network.
How to undertake a Pre-Deployment Survey
The pre-deployment phase requires a powered AP to be used. For this, we have designed and built our own battery powered rigs. These are neat and are built into a case so they can fly - we conduct site surveys across Australia and NZ, so the ability to fly is an important one!
Modern APs cannot just be plugged into a power source though - they have to detect a switch or they will not switch their radios on. We've overcome this in our rigs and built in the required circuitry to allow the APs to be powered. For the rigs, we have built different brackets to support different AP types across the Cisco and Aruba ranges, so we're ready at any time to conduct site surveys.
The pre-install survey is essentially then a matter of placing the powered AP in the locations we've selected and surveying. The survey results should match our predictive model - if they don't we work out if the walls are more or less attenuating than in the original predictive model. It's not always a case of adding more APs either - sometimes the survey shows the opposite and APs are removed.
Wi-Fi Pre-Deployment Surveys: Summary
Wall densities, roof types and incorrect maps are all things that can be corrected by going to site for a pre-deployment survey it is extremely valuable information to have when designing a network.
Wi-Fi design takes place across two stages - the Wi-Fi Predictive Design and the Wi-Fi Pre-deployment survey.
There are a range of other surveys available too, which are used for different purposes.
To have a network that was designed correctly with the correct information can save you a lot of money. Having attended a lot of sites which don't have the right AP density, I can say it is way cheaper to design it right the first time around.
Need some help with your RF designs? Please contact us.