conducting site surveys for wlan performance and reliability

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Copyright Airmagnet


  • 1. Conducting Site Surveys forWLAN Performance and Reliability Mike Diss SE, EMEA, AirMagnet [email_address] June 16, 2010

2. AirMagnet Overview

  • Founded in 2001; based in Sunnyvale, California, USA
  • Amassed over 8,500 customers 75 of the Fortune 100
    • 25,000+ Product Licenses Sold
  • Worldwide support in more than 120 countries
  • Global footprint of authorized resellers and distributors
  • Recently acquired by Fluke Networks (Worldwide HQ: Everett, WA)

AirMagnet is the leader in wireless LAN security, performance and compliance solutions for wireless LANs. 3. WLAN Lifecycle: Best Practice to Cope with Constant Changes in Wireless

  • Pre-Deployment Design and Planning
    • Design wireless network tailored to environment, user and application needs
  • Operational Management
    • Proactively monitor WiFi, RF, Voice performance to identify problems before impact
  • Security Management
    • Iron-clad protection with visibility and defense from all forms of wireless threats

4. Conducting Site Surveys forWLAN Performance and Reliability 5. History of WLAN Design Goals

  • Old Way
    • Minimum # of Access Points
    • Maximum Power
    • 30+ Users per AP
    • Bandwidth what Bandwidth
  • New Way
    • 10 Users per AP
    • Minimum Power
    • Lots of Access Points
    • Network Performance (& Signal Quality) is Paramount

6. Need for Site Surveys

  • New Installations
    • How many APs needed?
    • Where should they be placed?
    • How should they be configured?
  • Existing Installations
    • Were the correct number of APs deployed?
    • Were they deployed in the best location?
  • Ongoing Network Optimization
    • Support for new users
    • Support for new technology
    • Support for new applications

7. Site Surveying Phases

  • Preparation
  • Site Survey
  • Analysis
  • Reporting & Sign-off
  • Periodic Site Surveys

8. Phase 1: Preparation Phase

  • Preparation checklist Questions to ask
    • Do you know all the stakeholders?
    • Is wireless access needed for indoors or outdoors or both?
    • Are any building blueprints or street maps available?
    • Where do you require coverage?
    • What type of business is it?
    • Is this a new deployment or an add-on to the existing one?

9. Phase 1: Preparation Phase (Continued)

    • If adding to an existing wireless network:
      • Are you unhappy with it? Are users complaining? Or is your business expanding?
      • What equipment have you installed? Where are they installed?
    • Think about capacity
      • How many users require wireless service and what applications will they use?
      • What is the geographical distribution for the users?
      • Will they be using applications where they need to roam? What are their throughput requirements?

10. Phase 1: Preparation Phase (Continued)

    • Are there any known major non Wi-Fi interfering sources? Do you know their locations?
    • Is this a multi-floor deployment?
    • What are the security requirements?
    • Where are the power and Ethernet drops throughout the facility? Is the customer open to installing new drops?
    • What is the anticipated growth for the future?

11. Phase 1: Preparation Phase (for 802.11n)

  • Questions to ask for 802.11n networks
    • Am I deploying an 802.11n Greenfield network or do I need to support legacy 802.11a/b/g devices?
    • Will the 802.11n devices be deployed in the 2.4 GHz or 5 GHz Band? Or do you want the Site Survey product to recommend the choice?
    • What type of clients will be connecting to the network?
    • Will I deploy 802.11n devices for my Guest Network?
    • Do I see coverage overlap from APs that belong to my neighbor? Is that coverage from 802.11n or legacy 802.11a/b/g devices?

12. Phase 2: Site Survey

  • Load floor plan maps
    • Supported format
    • Simple, black and white plans
    • Calibrate your floor map scale
  • Survey tips and tricks
    • Perform a visual inspection of the facility
      • Can I get everywhere I need to?
    • Figure out where you require coverage and where you dont including areas that obscure results
    • Perform survey during normal business hours
    • Dont scan unwanted channels
      • Exterior survey to discover RF channels being used

13. Phase 2: Site Survey

  • Survey tips and tricks
    • Make good judgement on the Signal Propagation Assessment value
    • Measurement intervals accuracy
      • Auto Logging Data Period
      • No further than what your Signal Propagation Assessment is set to
    • Take readings on both sides of the wall
    • Also take readings along the perimeter of the rooms
    • Recommendation:Plan your walking path
      • Results in more accurate clicking

14. Phase 2: Site Survey

  • Survey tips and tricks
    • Take readings around the outside of your building
    • Place your man where you are headed for and then click when you reach that location
    • Dont try and do it all in one go
      • Enable you to retract when necessary
    • Switch between auto sampling and click only sampling as you walk around
      • Auto sampling for straight line walks (i.e. corridors)
      • Click only for points within a room
    • Size of hashing at click points indicates range of Signal Propagation Assessment

15. Phase 2: Site Survey

  • Perform your surveys
    • Passive Surveys
      • Collect signal data from all APs & Stations in the area
    • Active Surveys
      • Collect actual performance metrics (data rate, retries, etc)
      • Mandatory for 802.11n deployments
    • Iperf Surveys
      • Collect uplink/downlink performance statistics

16. RF Spectrum Site Survey

  • Gather RF Spectrum Data
    • Non Wi-Fi devices operate in the same spectrum as Wi-Fi
    • Cause interference and severely degrade the overall network performance
    • Even more important for time sensitive applications
    • Locate interfering devices on floor map
    • Preferred method: Collect RF data at the same time as a Wi-Fi Survey

17. Phase 3: Analysis Phase

  • Visualize Wi-Fi signal coverage
  • Visualize real-world user performance metrics
    • Data rates, retries, losses
    • Uplink/downlink performance
  • Visualize Roaming areas
  • Visualize areas that suffer from Channel Interference

18. RF Coverage Analysis

  • Visualize Wi-Fi signal coverage at every location
  • Locate dead spots in your coverage
  • Know coverage for yo


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