Hey!
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
- Capture what Ekahau can’t capture
- 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
- Generic (band agnostic)
- 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
- Incorrect type of APs/Antennas used
- 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
- Re-design of physical WiFi
Cheers and tons of love,
Your Ninjas.