Slides - Ekahau

Efficient RF Design of
Wi-Fi Networks
Jussi Kiviniemi / Ekahau
Download slides: ekahau.com/Jussi
Jussi@Ekahau.com
“
Always design the network as if you will
take the support calls personally
Darrell Derosia
Wi-Fi Architect
AGENDA
• The usual yada-yada
• Tips for
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Predictive design
Pre-deployment site surveys
Post-deployment site surveys
Spectrum analysis
Who is the guy with the thick accent?
• Jussi Kiviniemi
• (bald) Head of Wi-Fi Design Tools biz
at Ekahau
• Joined Ekahau in 2002
• Twitter: @jussikiviniemi
• Linkedin: linkedin.com/in/jussos
• Download slides: ekahau.com/jussi
CWNP & Ekahau Wi-Fi Design Tools
• Ekahau has worked with CWNP
since the beginning
• Provide site survey & planning
tools to CWNTs to use in classes
• Speak at CWNP Conferences
Mark Your Calendar
CWNP Wi-Fi Trek
• September 24-26th
• San Francisco, CA
• Hear the latest in Wi-Fi
• Meet the Wi-Fi rock stars
Ekahau Wi-Fi Tools
Mobile Survey for Android
Site Survey & 3D Planner
Spectrum Analyzer
Interference Analysis
Keith Parsons
•
•
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Trained Wi-Fi for 10+ years
3,000+ engineers trained
Deployed Wi-Fi from Arctic
Circle to Antarctica
Amanda Björnberg
•
•
•
Ekahau video trainer
Host of dozens of training
videos
Helps you master Ekahau
products
Participate in making our stuff better
• Meet Harri,
Ekahau Thesis Guy
• Harri is working on his master’s
thesis
• Understand the work of Wi-Fi
engineers
• Improve the usability of Ekahau
products
• Come up with new product ideas
• Contact  harri@ekahau.com
to participate
Why pay attention to Wi-Fi Design
• Troubleshooting and fixing
a badly built network can
take months
• Pictures: bad-fi.com
Unlicensed Spectrum
Here’s Wi-Fi traffic
Non-Wi-Fi interference is like…
2.4GHz Wi-Fi Overview
• 3-4 non-overlapping
channels
• Americas:
1-11 (1,6,11)
• Europe:
1-13 (1,6,11 or
1,5,9,13)
5GHz Wi-Fi Overview
• 25 non-overlapping
channels in the US
(36-64 [8], 100-144 [12],
149-165 [5])
• Less crowded than
2.4GHz
• Not all devices support it
Life Cycle of a Wi-Fi Network
Continuous
Periodic Checkups
Monitor
Troubleshoot
Packet analysis
Spectrum
analysis
Preparation &
Requirements
Plan
Predictive
Design
PreDeployment
Site survey
Validate
Installation and
Configuration
Post-Deployment
Site Survey
Life Cycle of a Wi-Fi Network
• Wi-Fi design is an iterative process
• Work through options and adapt
• RF is alive all the time: Come back
after 6 months and you’ll find it quite
different
Preparations
• Learn Wi-Fi
• CWNP: High quality vendor neutral Wi-Fi
expert training
• Blogs (Revolution Wi-Fi, WLAN Pros, Lee
Badman, SC-Wi-Fi, NSA Show podcast)
• Vendor-specific courses: Cisco CCNx,
Aruba, Ekahau ECSE …
Management Buy-In
• You will need the management to
commit to the project…
• … to ensure sufficient
• $
• Time
Preparations
• Work with it: Nothing replaces field
experience
• Have your tools ready to go
• Learn your tools BEFORE going on-site
Preparations
• Reserve enough time, so you won’t
deploy this 
Preparations
• Familiarize yourself in advance
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Point of contact for complications
Access to areas
Advance notification to staff
Double-check the intended schedule and scope
of work
“
Designing to a budget is designing to a
WLAN failure.
Keith Parsons
Wi-Fi consultant and trainer, industry innovator
Gathering Requirements
• Sit down and talk to people!
• Network end users
• IT people
• Management
Source: Dilbert.com
Gathering Requirements
• Know exactly what areas need to be
covered and surveyed
• Restrictions: Where APs can NOT
be placed
Key Requirements
• Coverage areas
• On a map
• ALL of them
• Number of users
• Per user group
• Account for growth
• The applications used
• Per user group
• Affects coverage requirements,
and capacity
“
“If you fail to plan, you plan to fail.”
Nowhere is that as true as with designing and deploying Wi-Fi networks
Karl Schmidt
Sr. Network Engineer, NEC
Predictive Design
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Accurate scale is everything
•
Do it carefully:
Garbage in, garbage out
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Remember directional antennas
(including up/downtilt), and floor-tofloor radiation
•
Never trust an “Auto-Planner” blindly.
Tips: Faster predictive design
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Save hours or days:
Get CAD drawings
– Wall information available in CAD
drawings
– Get accurate scale automatically
If you don’t have CAD drawings, draw the
main walls, don’t overdo it
Tips: Faster predictive design
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Observe signal strength to find initial AP
placements
Then observe channel overlap to find ideal AP
channels (if manual channel assignment
used)
Finally check with data rate / throughput and
capacity heatmaps
Coverage and overlap requirements
• AP vendors have their
guidelines
• Ask also industry experts
Plan for Capacity
• User groups
• Device types
• Number of users & their devices
• Applications run on each device
“
A site survey is worth
a thousand support calls
Andrew von Nagy
Revolution Wi-Fi
Pre-Deployment Site Surveys
• Purpose: Use a couple of “APs on a
stick” on-site to make measurements
prior to deploying the entire network
• What to measure? Coverage and SNR
at the least. Preferably throughput,
spectrum.
Pre-Deployment Site Surveys
Best practices for pre-deployment
survey
• Use reasonable Tx power (not max or
min )
• Turn back at the edge of desired cell
coverage
• Use multiple Wi-Fi adapters to
measure faster, walk faster
Post-Deployment Site Surveys
• Purpose: Validate the coverage and
performance of the entire network
• Multiple Wi-Fi adapters make the
walking faster
• Requirements? Every room, or
every other enough?
• What to measure? Coverage, SNR,
throughput. Jitter (VoIP). Spectrum.
Tools to Fight Interference
• Spectrum analyzer
• Site survey tool
• A hammer ;)
Spectrum Analyzer:
Go CSI on your Wi-Fi
1. What’s Wi-Fi, what’s not
2. How bad is the
interferer – amplitude,
duty cycle and channel
3. Is the interferer constant
or periodic in nature?
Spectrum Analysis:
Wi-Fi vs Not Wi-Fi
Wi-Fi
Not Wi-Fi
Spectrum Analysis:
Questions before acting
• Is the interferer impacting your network?
• Can the interferer be eliminated?
• Will adjusting the network fix the problem?
• Is there a Wi-Fi substitute for the interferer?
• Can you break it?
Network Health Check
• Some invest in additional
infrastructure to monitor WiFi
• If you don’t, perform quick,
periodic health check site
survey walks as often as
possible (doesn’t take long).
Easy to walk, give to expert
to analyze
Wrap-Up: How to make things
More efficient
Eliminate or minimize the repetitive work.
Focus on learning the advanced stuff.
1. Design your wireless LAN carefully.
Save time with the use of CAD
drawings
2. Test and optimize the network
periodically
3. Familiarize yourself with the right tools
and best practices to make periodic
check-ups and troubleshooting
effectively
Wrap-Up: Top 3 Tips
1.
Get management buy-in
2.
Get knowledge and experience
3.
Best practices are there for a reason
“
Always design the network as if you will
take the support calls personally
Darrell Derosia
Wi-Fi Architect
Let’s look at a few examples
ekahau.com/wifidesign
Twitter: @ekahau
Mail: wifidesign@ekahau.com
Blog: ekahau.com/wifidesign/blog
Phone: 1-866-4EKAHAU