WLAN Design Fails – welcome to the Wi-Fi wall of shame

Designing Wi-Fi ain't just throwing boxes on ceilings. Screw it up, and you’re in for dropped calls, angry users, and support tickets till you die.

Classic Design Crimes – the “bad design” section

  • Insufficient coverage: You got holes, dead zones, slow corners. Clients crawl or fall off. You need proper signal where people are. Period.
  • No capacity thinking: Just 'cause there's signal doesn't mean it works. 100 users on 2 APs? Good luck. You need throughput, not just green dots.
  • Scalability who? Built for today, dead tomorrow. Add users, boom – it collapses. Design needs growth space, man.
  • Missing features: Got coverage but no onboarding? No roaming? No guest? Congrats, your network’s technically useless.

Cookie-Cutter Design – copy/paste stupidity

  • Overkill hardware = empty wallet: "One AP per room" sounds safe… till you realize you're burning budget for no reason.
  • Underkill = rage: Not overbuilt? Cool. Now it's underbuilt. Welcome to buffering land. “Coverage only” means performance hell.

No Design – like, literally none

  • Slow creep deploys: You added APs randomly over 3 years. Now it’s RF chaos, like 10 radios yelling on the same channel.
  • Plug it where Ethernet is: Ethernet’s not a design tool. Putting APs only where there’s cable = blind coverage and wasted gear.

Bonus screw-ups – the deep cuts

  • No Define phase: No clear requirements = no hope. If you don’t know apps, devices, business needs – you’re designing in the dark.
  • Ignoring the building: Concrete, steel, weird ceiling heights – all ignored? Yeah, your RF predictions are now fan fiction.
  • RF analysis? Nah: Didn’t check noise, SNR, or Bluetooth wars going on? You’re flying blind.
  • No post-survey: You didn’t validate. Your APs look nice but don’t work right. Nobody’s surprised but you.
  • APs in dumb places: Wrong height, wrong power, wrong antenna = bad signal. RF doesn’t care how clean your install looks.
  • Channel mess: CCI, ACI everywhere. Especially in 2.4 GHz, where there’s only 3 usable channels and you somehow use all 11.
  • QoS? What QoS? Voice and video die without it. Latenz ist King. You miss that, you miss the point.
  • No line of sight: Doing mesh or bridge? If you block LoS or 1st Fresnel, your link’s toast.
  • Bad survey skills: You scanned all channels “just in case”, clicked the wrong spot on the floorplan, skipped passive – now your data's trash.

Design like you mean it

A good WLAN design needs brains, not guesswork. Know the RF, know the needs, plan hard, test harder. Get it wrong, and your inbox will explode. Get it right, and users won’t even notice it exists – which is exactly how it should be.

Insufficient Coverage – when Wi-Fi just ain't there

This one’s a classic. You think you got Wi-Fi, but users are falling off the edge. We’re talkin’ dead zones and turtle-speed signal. It’s not just annoying – it kills apps, calls, and your rep.

What it really means

  • Dead spots: No signal. Nada. Clients drop or can’t connect. Users rage.
  • Low-data-rate zones: Wi-Fi’s there, but it’s crawling. Video? Nope. VoIP? Forget it.
  • Fix it? You need proper coverage. That means strong enough signal + stability for the apps clients actually use.

Where the mess starts

Bad Design = Bad Wi-Fi
  • No coverage: You guessed wrong or didn’t care. Now the signal doesn’t reach.
  • No capacity: Signal’s fine, but it can't carry the load. Throughput dies.
  • No growth: You built for today, forgot tomorrow. Add more users, it burns down.
  • No features: Roaming? Guest? Onboarding? If you didn’t plan it – it’s not there.
Cookie-Cutter Designs (aka Lazy Copy/Paste)
  • “1 AP per classroom” they said. “It’ll be fine” they said. But it’s not.
  • Coverage-only mindset = low user satisfaction. You get what you settle for.
No Design at All – just vibes and cable ports
  • Organic growth gone wild: You added APs over time, now it’s a CCI party with poor planning.
  • Wherever there’s Ethernet: You slapped APs near ports, not users. Congrats – you covered the janitor’s closet.

Other classic fails that wreck coverage

  • Weak requirements phase: Didn’t ask what the business needs? Congrats – now it’s a guessing game.
  • Ignored the walls: Concrete, steel, weird layouts – didn’t account for 'em? Your RF map's now fan fiction.
  • Didn’t study RF behavior: You skipped checking interference, SNR, RSSI, Noise. Now the clients suffer.
  • Wrong AP placement: Height, tilt, location, power – you messed it up, and now your signal’s gone sideways.
  • No channel plan: You got APs yelling on the same channel, stepping on each other’s toes. Classic CCI/ACI mess.
  • No post-survey: You didn’t check your install. Users are your QA team now – bad move.
  • Bad survey tools: Used the wrong gear? Didn’t measure both sides of walls? Skipped passive scans? Boom – useless data.

Wanna fix bad coverage? Stop wingin’ it. Do your homework. Know the space, know the tech, validate everything. Design like you give a damn – or brace for helpdesk hell.

No Capacity – when your Wi-Fi's outta gas

So your signal bars look good... but your apps still crawl? Yeah, that's No Capacity. Means the network can’t handle all them hungry clients beggin’ for bandwidth. Coverage is there, but throughput’s crying in a corner.

Where it all goes sideways

Bad Design – the usual suspect
  • Too few APs, too many users: Everyone’s fighting for airtime. Nobody wins.
  • No scalability: Built for yesterday, breaks tomorrow.
  • No features: No onboarding, no guest access, no plan. Congrats, it's chaos.
Cookie-Cutter Disaster
  • “1 AP per room” they said... but forgot to check what folks actually do in there.
  • Low-density design in a high-density world? Nah. That’s a bottleneck with extra steps.
No Design? No chance.
  • APs slapped near Ethernet ports: Good for switchports, bad for users.
  • Grew like weeds: Threw in APs as needed. Now it’s CCI city and nothing works right.

Other juicy mistakes killing your capacity

  • Didn’t define needs: No clue about user count, apps, client types? That’s planning with your eyes closed.
  • Overpowered APs: Big signal, big problems. Too many clients on one cell = slow everything.
  • No channel planning: CCI and ACI got your airtime on lockdown. Every packet waits in line.
  • Ignored density: Lots of people? You need more APs, lower power, tighter cells. Duh.
  • No QoS: VoIP sounds like a robot in a blender. Video buffers forever. Priorities, people!
  • No validation survey: Didn’t test after install? You’re flying blind and wondering why Zoom keeps freezing.

So how do you fix this mess?

Design like you mean it
  • Add more APs if the place is jam-packed.
  • Turn down AP power. Go small cell, go smart.
  • Plan your channels. Don’t just hope for the best.
  • Design for the weakest client – not your shiny MacBook, but grandma’s barcode scanner.
Config like a pro
  • Turn on RRM – let the system adjust when things get noisy.
  • Band steering: Push dual-band clients to 5 GHz and free up 2.4 GHz.
  • Load balancing: Don’t let one AP do all the heavy lifting.
  • Airtime fairness: Give everyone a turn, even the slow kids.
  • Drop those low data rates – force clients to roam, not cling to weak signals like it’s 2009.
  • Make sure QoS tags are real and respected. DSCP ain’t just alphabet soup.
Validate or suffer
  • Do post-install surveys. Like, really. Not just one walk with your phone.
  • Use iPerf, TamoSoft, whatever floats your packets – test real throughput.
  • Sniff the air – protocol analyzers, spectrum tools, full nerd mode. Find that interference monster.

Wrap-up: It ain’t just signal strength, bro

You can have five bars and still be toast. Capacity is about airtime, design, and smart planning. Build for what people do, not just where they sit. Plan, test, tune, repeat. Or just keep rebooting and praying. Your call.

 

Channel Interference – When Wi-Fi Gets Cranky

Yeah, even if your signal bars are full, your Wi-Fi can still suck. Why? Two words: Channel Interference. It’s like trying to have a convo at a concert – everyone’s yelling, and nobody hears a damn thing.

Types of Interference – The Usual Suspects

1. Co-Channel Interference (CCI)

Same channel, same area. Two APs shoutin’ on the same radio station. Now they gotta take turns talking, which means everyone waits. It’s not the AP’s fault alone – your clients (laptops, phones, that smart fridge) are all guilty too.

Why it happens: Lazy planning. Tossing APs into the ceiling wherever there’s an Ethernet drop. Adding more APs over time without thinking. Crowd the channel, kill the speed.

2. Adjacent-Channel Interference (ACI)

This one’s sneakier. It’s when you use channels that are too close together – like 1, 2, 3 – and they overlap. Especially messy in 2.4 GHz land where channels are too chubby for their own good. Even 5 GHz isn’t safe if you go wide with your channels or jam antennas together.

Fixing the Mess – What You Can Actually Do

1. Smart AP Placement
  • Use more APs but turn the power way down. More small cells, less shouting across the room.
  • Don’t stack APs on top of each other floor-to-floor. You’re just making vertical noise.
2. Good Ol’ Channel Planning
  • 2.4 GHz: Stick to channels 1, 6, 11. Period. No heroes here.
  • 5 GHz: You’ve got more room, so spread out. But don’t go crazy – keep ‘em spaced.
  • Use narrow channels (20 MHz) in crowded places. Less overlap, more happy clients.
3. Adjust That Power
  • Too much power = interference. Too little = dead zones. Find your zen.
  • For wireless bridges? Match the power on both ends. No drama.
4. Antennas Matter
  • Directional antennas = aim the signal, reduce the noise. Boom.
  • Pick antennas that fit the space, not just what looks fancy on a spec sheet.
5. RRM (Radio Resource Management)

Let the system auto-magically tune channels and power. Just don’t expect miracles. Still needs a brain behind the scenes.

6. Airtime Tricks
  • Band Steering: Push dual-band devices to 5 GHz. 2.4 GHz is already overloaded like a German Autobahn at rush hour.
  • Load Balancing: Don't let one AP babysit 100 devices while another naps. Spread the love.
  • Airtime Fairness: Don’t let old, slow clients hog the mic. Share it better.
  • Kill low data rates: Turn off 1, 2, 5.5 Mbps if you can. Speeds things up but might create holes. Use with caution.
7. Validate Like a Pro
  • Run a post-install survey. Don’t just pray – verify.
  • Use tools like:
    • Spectrum analyzers – find rogue microwaves and other crap.
    • Protocol sniffers – see who’s chatting too much or too slow.
    • Throughput testers – make sure the network isn’t just a paper tiger.
    • Survey software – because heatmaps look cool and also tell you where things suck.

Interference kills performance. Doesn’t matter how many APs you got if they’re yelling over each other. Plan better, place smarter, and validate always. Or keep rebooting your Wi-Fi and wondering why Netflix buffers every damn time.

 

Post-Installation Site Survey – The Final Exam for Your Wi-Fi

You can design all day and hang APs like holiday lights, but if you don’t run a Post-Installation Site Survey (aka validation survey), you’re basically flying blind. This is where you find out if your Wi-Fi’s just good on paper, or actually holds up in the real world.

Why You Gotta Do It

  • Check Your Homework: Did you actually build what you designed? Signal’s not enough. You need to validate coverage, capacity, and function. Otherwise, congrats – you built a nice failure.
  • Reality Check on RRM: Even if you’re using fancy auto-stuff like Radio Resource Management (RRM), don’t trust it blindly. Validate that it’s not goin’ rogue.

What You Should Be Looking At

  • Coverage: Not just “can I see an AP?” – we’re talkin’ good signal (RSSI), strong SNR, and enough APs in view for decent roaming. Weak coverage = dead apps = angry users.
  • App Performance: Voice, video, data – does it all run smooth, or does VoIP sound like a broken fax machine? This is where you find out.
  • Capacity Under Load: Simulate real usage. Connect a bunch of clients and see if your WLAN holds up or melts down.
  • Load Handling: One user’s fine. Ten’s okay. A hundred? You better hope your design holds, or you’re gettin’ calls.

Find the Skeletons in the Closet

  • Bad configs: Wrong channels, power too high, features off that should be on (Band Steering, Aggregation, etc.)
  • Hardware flubs: Missed APs? Too many? Not enough? Wrong spots? Fix it before the launch party.
  • Interference party: Post-surveys are how you catch CCI/ACI and random non-Wi-Fi crap (microwaves, wireless cams, etc.). Break out the spectrum analyzer.

Before You Go Live – Tune It Up

Post-survey lets you tweak the system before it goes into production. Fix it now or cry later when users start lighting up your inbox with complaints.

Use the Right Tools

  • Passive Surveys: For mapping out signal strength, interference, and if your channels make sense.
  • Active Surveys: Actually test throughput and client experience. You’ll see if Beamforming’s workin’ or not.

Skipping the Post-Installation Site Survey is like skipping a test drive on a race car you just built. It might start. Doesn’t mean it’s race-ready. Validate. Always. Your users will thank you (or at least, stop yelling).

 

If you got the feeling now like “Yeah, I totally get Wi-Fi!” – then uh... nope. That was just a Design - Fail show up, my friend. There’s a whole bookshelf waitin’ for you if you wanna be a real Wi-Fi geek. CWNA, CWAP, CWDP, CWSP... yeah, it’s a ride. Buckle up.

Just a quick FYI:
This article’s got no tables or fancy graphics – on purpose. It’s built that way so screen readers and text-to-speech tools don’t freak out. Keepin’ it clean for the accessibility crew.

Heads up, Wi-Fi nerds:
This whole guide was put together using the CWNP books CWDP and CWAP. All the deep-dive stuff about Design and Failures, 802.11 weirdness, and packet wrangling comes straight outta those.

Written by: Enrico Aderhold
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