WiFi Troubleshooting

WN Podcast 051 – Validation Survey


Validation Survey, next to the Predictive Survey & Design, is the most popular type of the engagement we do in the WiFi consultancy world. We won’t exaggerate when we say we do it at least weekly and that validating / troubleshooting WiFi is a totally crucial skill.

Here is the video version of the Podcast – you can peek at our Ekahau Validation Survey template:

And here is what we have discussed:

  • Multiple names for the same thing
    • RF Assessment
    • Validation Survey
    • Troubleshooting Survey
    • It’s actually very similar to Post Deployment survey 
  • Targeting brownfield sites
    • Capture ‘as-is’ state of WiFi
    • Data captured is used to produce an easy to read ‘summary’ followed by simple ‘recommendations’
  • Why do clients ask us to perform a Validation Survey
    • Documentation purposes
    • Having issues that are most likely related to RF (physical side of WiFi) and must be identified and rectified
    • Building business case for re-design
    • Often sold together with Configuration Assessment
    • Often leads to more business
      • Be honest and don’t exaggerate
  • How and what do we capture on-site
    • Go on site
    • Perform full, detailed, passive survey with a survey tool of your choice
      • Active vs passive – why Ekahau is not best for active
      • Best active survey test – check if WiFi works for what it was designed for
        • Voice & video – can you have a good quality call? If not – why?
        • Basic data – can you browse, scan barcodes etc.?
      • If you must do throughput test, do them locally (ePerf, WLANpi throughput test) 
      • Ping is a poor test in WiFi due to the nature of how WiFi works – DCF aka ‘The Game’
    • Grab results of your fav WiFi Scanning tool
      • Capture what Ekahau can’t capture
        • Info from QBSS data like number of associated stations, AP reported channel utilisation
        • Amendments used
        • Authentication type used
        • SS info and more
      • On top of helping understanding RF better, quick WiFi scan can identify tons of common configuration issues without having to review the configuration
    • Be accurate
      • Click where you are
      • Don’t walk on water
      • Use good quality floor plans and measure with laser tool if required
  • What do we include in the Ekahau template – quick template demo
    • Ekahau captures tons of data and gives us access to tons of different heatmaps
    • Don’t include everything, include only what is relevant for your project
    • Here are the heatmaps and other info from Ekahau that we include in our Validation Survey documents:
      • Generic (band agnostic)
        • Requirements & Areas
        • Access Points
        • Survey Routes
        • Associates APs (make sure to use ‘measured’)
        • Capacity Health
        • Data Rates
        • Throughput (only if done local tests)
        • RTT (very infrequently)
      • Per band (same heatmaps for 2.4 and 5)
        • Coverage per AP
        • Primary Signal Strength
        • Secondary Signal Strength
        • Interference / noise
        • SNR
        • CCI
        • Network Health
        • Network Issues
        • Spectrum Utilization
        • Channel Width
    • What we don’t include 
      • Capacity: Clients per AP – predicted, no value
      • Channel Coverage – can’t see a use case
      • Channel Interference – predicted, no value
      • Jitter – not best metric
      • Number of APs – use secondary coverage instead
      • Packet loss – exaggerated in Ekahau, not great metric
      • RTT – not best metric
      • Spectrum Channel Power – can’t see use case
      • Difference in Signal Strength – can be valuable to compare surveys, but never used it
  • What do we include in the Summary
    • A sentence or two about all heatmaps
    • DFS condition check
    • Types of APs / Antennas used, their suitability against env they’re in and requirements, mounting
  • Typical issues
    • Incorrect type of APs/Antennas used
      • Tendency to be scared of directional antennas
    • Dual band operation
      • Band select used
      • Some devices on terribly bad 2.4GHz
    • Coverage and SNR
      • Not sufficient coverage
      • High non-WiFi interference
      • Low SNR
    • Tons of rogue APs on site
      • Old overlays, hotspots, click shares
    • Excessive CCI 
      • Not unusual to see 30+ in central London on 5GHz
    • Not enough APs
      • Capacity requirements not met 
      • Sometimes a 100 or more associated stations
    • Insufficient secondary coverage
    • Poor WLAN config
      • No amendments used
      • Low data rates enabled
      • APs covering too much – 15m high omnis in WH?
    • High spectrum utilisation
      • More devices using WiFi than scoped
      • WiFi and non-WiFi interference
      • Too many SSIDs – seen 16 more than once
    • High packet loss
      • High airtime utilisation = tons of retransmissions = packet loss
    • Site heavily affected by DFS
  • Typical recommendations (just an example, can vary vastly)
    • Re-design of physical WiFi
      • Different APs, different antennas types, different mounting
    • Disable 2.4GHz
    • Set 5GHz statically to 20MHz
      • Channel width set to best is sometimes crazy
      • Use 40MHz until you can’t
    • Enable some amendments
      • 802.11r
      • 802.11k
    • Disable low data rates
      • 12 or 24 mandatory is typically OK with all lower disabled and all higher supported
    • Limit min and max Tx power levels in RRM
      • 5GHz should be ‘louder’ than 2.4GHz – at least 6dBm difference
      • Typical Tx levels for 5GHz – around 14-17dBm

Cheers and tons of love,

Your Ninjas.

WN Video 007 – WiFi Explorer Pro

In this video Matt from WiFi Ninjas takes you through the amazing piece of software from Adrian Granados – WiFi Explorer Pro.

Matt shows you how he has his WiFi Explorer Pro set up with his columns, what external WiFi devices/ adapters you can plug into WiFi Explorer Pro and much more!

You can download your copy of WiFi Explorer from Adrians new website: https://www.intuitibits.com

Matt referred to the Wireless Adjuster class from Devin Akin that he sat quite recently and learnt how to unlock and use even more features of WiFi Explorer Pro – we highly recommended this class. You can find out more about the Wireless Adjust class here: http://divdyn.com/wireless-adjuster-course-level-ii/

WN Video 004 – Ekahau Analyser

Matt shows you one of the WiFi tools he uses when on customer sites – the Ekahau analyser app on iOS.

This WiFi tool is great for on the go troubleshooting and spectrum analysis. You can find out more about Ekahau from here: https://www.ekahau.com

This video was made using Ecamm Live, you can find out more about Ecamm live from our referral link: https://www.ecamm.com/mac/ecammlive/?fp_ref=matt37

(you don’t get money off but we will get a small commission if you use our link)

WN Podcast 041 – Wireless Adjuster with Devin Akin

Welcome the latest WiFi Ninjas Podcast episode!

We have recently attended Devin’s virtual Wireless Adjuster class and absolutely loved it!

Content, delivery and technical depth are top notch. We both feel the WA bridges the gap between CWNA and CWAP perfectly and it is exactly what was needed on the market.

If you are worried that using ‘just’ WiFi analysers is ‘too easy’, worry not! This course is perfect for everyone on every level from CWNA to CWNE and beyond. Tips & tricks are so great, we are still excited about it even few weeks after attending the class.

We never imagined it was possible to use WiFi Explorer Pro or WinFi that efficiently and for so many scenarios.

Can’t recommend WA with Devin enough! We’re sure you’ll love it as much as we did. Every freaking second of it. Did we mention amazing labs? Arrrrggh, getting overexcited.

Listen to the show, with Devin as our very honoured guest, get pumped up and book your sit in the class. It’s worth it.

You can download WiFi Explorer Pro from clicking here


Tons of love x,

WiFi Ninjas