How to get ready to validate a Wi-Fi infrastructure

September 12, 2016

exit survey, site survey, survey, validation survey

I first wanted to call this article “How to get ready for a validation survey”. However, following the talk from Jake’s blog post on the importance of functional validation testing along with the actual validation survey, I decided to give it this present title. Indeed, I totally agree with Jake that validating the performance of a Wi-Fi network requires more than a validation survey.

This article will answer the following questions: What does it take to get ready to perform the validation measurements? How do I get ready? What information do I need to gather? What equipment and tools do I need to gather?

CONTEXT

First, let’s talk about the context. When customers call to request a validation survey, it can have 2 different purposes:

Validate a new design and a Wi-Fi infrastructure that has recently been installed
Validate a current Wi-Fi infrastructure, usually because it is not performing up to their expectations

So the customers contact us to come and perform a validation survey (sometimes, other troubleshooting tasks can be requested). They usually have some, but limited Wi-Fi knowledge. They usually think that only coverage matters. Although coverage is important, it is not the only piece to validate if we want the Wi-Fi infrastructure to be meeting the business needs and requirements.

WHAT DO WE NEED TO GET READY?

So here is a list of things to do in order to get ready.

1 – Better understand what the business needs are
In order to better understand what the customer is expecting out of their Wi-Fi infrastructure, we need to understand what they want to do with it. So, for this task, you will need to engage a conversation with your customer asking questions such as (this is a non-exhaustive list):

How is the Wi-Fi network used? How would you want to use it?
What type of applications are you using? Are they business critical?
What are the problems you are currently experiencing (if any)?

The answers to these questions will help you define what you will be doing on site. For instance, if the customer tells you that they are experiencing more problems using a specific client device, you will be able to focus more attention and perform more testing directly from this device.

2 – Gather information about the network infrastructure
The goal of this task is to gather the information about the network equipment used. I am talking about the exact model of access points and wireless controllers as well as the OS version they are currently running. This allow us to perform some preliminaries verifications (known bugs, end of life support,…). It also allows us to gather all the vendor documentation needed in case we need it later once we are on site validating and troubleshooting.
Of course, don’t forget the LAN. Try to understand how the wireless equipment are connected to the LAN and what architecture is in use. At this stage, the best is to get a network diagram (if possible).

3 – Get an updated version of the floor plans
Obviously, this task is very important. I would emphasize on the word “updated”. A lot of good articles have been written on this topic so I am only going to give out a few tips that I use:

If you get the PDF version of the floor plans with colours, convert them to black and white. This allow a better reading of the results in your site survey program. Plus, it usually makes the file lighter.
If you get the PDF version of the floor plans, compress them in order for them to be lighter. This takes less time to load and process results in your favourite site survey program. A lot of website allow you to compress PDF files.
If you don’t have the scale on the floor plans, politely ask for it.
If they don’t manage to give it to you, use Google Earth to perform a first calibration using the building width or length. You will validate this calibration while on site using a measuring tool.

4 – Prepare your site survey files
At this point, you should have updated floor plans. You can then, create your site survey file(s) and calibrate your floor plans. If the facility you are studying is large and requires segmentation of your survey files, this can actually make you save some valuable time. This way, you can directly start your measurements as soon as you arrive on site.

5 – Get the current configuration of the Wi-Fi infrastructure
Ask your customer to provide the current configuration of their Wi-Fi infrastructure. Sometimes, they would even provide you with a remote access to their management console. From that, you will be able to perform a first validation of their configuration including:

Radio configurations: data rates, channels, Tx powers/EIRP, 802.11 protocol used
Number of clients and what 802.11 protocol they are using (are they any 802.11b clients?)
SSID profiles and their configurations (authentication, encryption…)

This will give you a good idea of what to look for when you arrive on site. Some changes can, sometimes, even be performed prior to the on site validation.

6 – Gather information about the client devices
Engage a talk with your customer about client devices and how they are an important part of their Wi-Fi system. They usually under-estimate this fact. Ask them what devices they are using on the Wi-Fi network including the name and model. Make sure you understand which one are working well and which one are having problems.
From that, you will be able to do your research and gather the Wi-Fi specifications of these client devices. These specifications includes:

IEEE 802.11 protocols supported
Frequency band supported (2.4Ghz only or dual band)
Maximum transmit power
Number of antennas
Maximum data rate supported
Drivers

When you ask about what devices are used over the Wi-Fi, don’t forget to ask what is their quantity and where they are use within the facility.

7 – Plan your physical access
Arriving on site to perform some work on a Wi-Fi infrastructure without having the proper access happened to me in the past. I ended up loosing valuable time getting these proper access. So make sure you plan in advance and arrange with your customer to have the proper access ready for you when you will be on site. Sometimes, an employee or security agent will be escorting you.

8 – Prepare your equipment
The last task will be to prepare your equipment. According to what tasks you will be performing on site, make sure you have all the equipment you need. Here is what I usually take with me when I go validate a Wi-Fi infrastructure:

A Site Survey Program (Ekahau Site Survey) and its USB dongles
2 laptops: I bring an extra one just in case I want to perform iPerf testing. I use this extra laptop as the iPerf server. This way I don’t have to bother the customer and I’m independent. You can also build a more portable solution (see link at the end of this article)
A spectrum analyzer program (Metageek Chanalyzer) and its adapter (Wi-Spy dBx)
Programs to perform packet captures and analysis (I like using AirTool, Wireshark and Metageek Eye P.A.)
A measuring tool (I use a measuring wheel)
A tool to validate the wired side (Fluke LinkSprinter)
A bunch of cables (you never know)
AirConsole and a console cable (you never know)

Feel free to bring the tools you are comfortable using.

This article only talks about how to get ready. Future discussions will probably arise related to what tasks can actually be performed on site to validate an overall Wi-Fi infrastructure. In the mean time, let me know how you usually get ready yourself?

Other Ressources:
– Why validation surveys aren’t enough, the importance of functional validation testings by Jake Snyder: http://transmitfailure.blogspot.ca/2016/08/why-validation-surveys-arent-enough.html
– Calibrating a WLAN survey plan by Nigel Bowden:
http://wifinigel.blogspot.ca/2014/09/calibrating-wireless-lan-survey-plan.html
– Building a portable Ekahau throughput (iPerf) server by Jerry Olla: http://www.ekahau.com/wifidesign/blog/2016/05/13/building-a-portable-ekahau-throughput-iperf-server/
– Blogs by our customers: from how-to-guide in-depths tricks by Ekahau: http://www.ekahau.com/wifidesign/blog/2016/02/10/blogs-by-our-customers-from-how-to-guides-in-depth-tricks/