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Performing a WLAN Site Survey. Define the need for and the use of a manual site survey tool and differentiate between the following manual site survey types Active surveys Passive surveys Define the need for and use of a spectrum analyzer in a manual site survey

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performing a wlan site survey
Performing a WLAN Site Survey
  • Define the need for and the use of a manual site survey tool and differentiate between the following manual site survey types
    • Active surveys
    • Passive surveys
  • Define the need for and use of a spectrum analyzer in a manual site survey
    • Identification and location of interference sources
    • Differentiation of Wi-Fi and non-Wi-Fi interference sources
  • Differentiate between manual and predictive site surveys
    • Advantages and disadvantages of each site survey methodology
  • Define the need for and use of a protocol analyzer in a manual site survey as it relates to the following
    • Identifying, locating, and assessing nearby WLANs
  • Differentiate between site surveys involving networks with and without a mesh access layer
performing a wlan site survey1
Performing a WLAN Site Survey
  • Define and differentiate between the following WLAN system architectures and understand site survey concepts related to each architecture. Identify and explain best practices for access point placement and density.
    • Multiple Channel Architecture (MCA)
    • Single Channel Architecture (SCA)
  • Identify limitations on hardware placement
    • Areas where APs or antennas cannot be placed
    • Areas beyond Ethernet distance limitations
  • Understand industry best practices for optimal use of directional and omni-directional antennas in site surveys
exam essentials
Exam Essentials
  • Understand the need for an RF spectrum analysis and how to locate sources of interference.
    • Know that an RF spectrum analysis will allow you to "see" RF in an area proposed for a wireless LAN. Identify different types of RF interference that can have an effect on a wire­less network.
  • Know the differences between manual and predictive site surveys.
    • Know that a manual site survey typically requires a complete walkthrough and testing throughout the proposed area where a wireless LAN will be deployed. A predictive site survey may require minimal time on-site and is a software-based analysis solution.
  • Identify two different types of manual site surveys.
    • Know that manual site surveys can be passive or active and the differences between each.
exam essentials1
Exam Essentials
  • Know how a protocol analyzer can be used as part of wireless LAN site survey.
    • Explain how a wireless protocol analyzer can be used to help identify existing wireless networks and how they may have an impact on the site survey.
  • Understand the importance of identifying existing wireless networks.
    • Know the impor­tance of existing wireless networks and how they may have an effect on a new wireless LAN deployment.
  • Be familiar with the limitations of placement regarding wireless infrastructure devices.
    • Explain some of the limitations regarding placement of wireless LAN devices, including access points, bridges, and antennas.
  • Understand the factors regarding proper antenna use.
    • Identify the different uses of anten­nas based on the customer requirements and characteristics of the environment.
performing a wlan site survey2
Performing a WLAN Site Survey
  • Previous Chapter was about paperwork and planning
  • This chapter about components and operations
  • RF Interferance
    • WiFi and Non-WiFi
  • Manual vs. Predictive
    • Manual Surveys
      • Active and Passive
  • Tools
    • Wireless Protocol Analyzers and Scanners
  • Different Channel Architectures
    • Multiple (MCA)
    • Single (SCA)

Pg 285

the physical site survey process
The Physical Site Survey Process
  • Up front work of gathering info, business requirements, site specific docs, defining physical and data security, user interviews
  • Now do the site survey

Pg 285

the physical site survey process1
The Physical Site Survey Process
  • Up front work of gathering info, business requirements, site specific docs, defining physical and data security, user interviews
  • Now do the site survey
  • Subjective and there are different opinions of how to do it.

Pg 285

the physical site survey process2
The Physical Site Survey Process
  • Arrange a walkthrough of the entire location
  • Take thorough notes
  • Perform RF spectrum analysis
  • Determine preliminary placement of infrastructure devices
  • Perform on-site testing
  • Determine actual placement of infrastructure devices
  • Install infrastructure hardware as specified
  • Perform on-site verification testing and make adjustments
  • Deliver final report

Pg 286

rf spectrum analysis1
RF Spectrum Analysis
  • Spectrum Analyzer
    • Shows frequency band usage
    • Physical layer hardware/software tool that analyzes radio frequency waveforms
  • Can be stand alone device or integrated into something else
    • USB or PC Card tools
    • Software that runs on existing wireless network card

Pg 286

rf spectrum analysis3
RF Spectrum Analysis
  • Find dead spots as well as interference
  • Regular analysis can be an important part of keeping a WLAN working at expected performance levels

Pg 288

wi fi and non wi fi interference sources
Wi-Fi and Non-Wi-Fi Interference Sources
  • Lots of devices operate in the uinlicesend 2.4 Ghz Ism and 5 Ghz UNII bands
    • Other WLANs
  • Non Wi-Fi examples
    • Microwave Ovens
    • Cordless Telephones
    • Bluetooth Devices
    • Medical Equipment
    • Manufacturing or industrial equipment
    • Wireless Security Cameras
    • Radar Systems
    • Etc

Pg 289

spectral analysis
Spectral Analysis
  • Chanalyzer on the CD
wi fi interference
Wi-Fi Interference
  • Co-Channel
    • Same channel
  • Adjacent Channel
    • Channel that overlaps
  • FHSS 2.4 Ghz
  • DSSS 2.4 Ghz
  • ERP-OFDM 2.4Ghz
  • OFDM 5 Ghz
  • HT-OFDM 2.4 Ghz and 5 Ghz

Pg 294

wi fi interference1
Wi-Fi Interference
  • WLANs that interfere could be ad-hoc or infrastructure
  • RF Spectrum Analysis can give you some indication of where the interference is

Pg 294

wi fi interference4
Wi-Fi Interference
  • CWNP defines
  • Adjacent Overlapping
    • Channels 1 and 2
  • Adjacent Non-Overlapping
    • Channels 1 and 6
  • Co-Channel
    • Two APs using same channel in same physical area

Pg 298

performing a manual site survey
Performing a Manual Site Survey
  • Provides accurate results
  • Requires a physical walk through
    • Record information to determine the performance of clients and devices
  • Record
    • Signal Strength
    • Signal to Noise Ratio (SNR)
    • Data Rate of connected devices

Pg 298

performing a manual site survey1
Performing a Manual Site Survey
  • Can use inexpensive tools or commercially designed software
  • Used to determine placement of hardware infrastructure
  • Can be time consuming and expensive
    • Especially at larger sites

Pg 299

obtaining a floor plan or blueprint
Obtaining a Floor Plan or Blueprint
  • Review floor plan
    • Often acquired during planning phase
  • Note AP placement
  • Note SNR readings and coverage

Pg 300

identifying existing wireless networks
Identifying Existing Wireless Networks
  • ID existing WLANs
  • Note coverage and RF interference
    • Can use free software like NetStumbler
    • Can use commercial software

Pg 300

testing access point placement
Testing Access Point Placement
  • Typically done with a mobile AP on a pole and a powered cart
  • The AP is moved from one location to another while the Site Surveyor takes measurements with RF Site Survey software.
  • Associate to device from site survey computer
  • Can even test actual devices and applications in some cases

Pg 301

analyzing the results
Analyzing the Results
  • Analyze results
    • Determine final placement
    • Make adjustments
    • Add access points
    • Different antenna choices

Pg 303

advantages and disadvantage of manual site surveys
Advantages and Disadvantage of Manual Site Surveys
  • Advantage
    • Very accurate
    • Physical characteristics are tested
    • Verification of actual RF coverage
    • Can mark exact installation locations
  • Disadvantages
    • Time consuming
    • Usually only one access point Used for testing
    • Requires walkthrough of entire location
    • May require an escort

Pg 303

software assisted manual site survey
Software Assisted Manual Site Survey
  • Manual Surveys can often be done with basic open source tools
  • Can also be performed with additional software that can help with
    • Performing active or passive surveys
    • Import floor plans
    • Automatically record data
    • Give a visual representation of RF signal
    • Perform post-survey analysis

Pg 303

passive site survey
Passive Site Survey
  • Monitoring the air and recording RF data from all access points and stations in “hearing range”
  • No association to AP
  • No traffic is passed between survey station and AP

Pg 304

active site survey
Active Site Survey
  • Survey machine associates to an AP to take readings
    • Some believe it is more accurate
  • Send and receive RF signals
    • Can record signal strength

Pg 305

active passive site survey
Active& Passive Site Survey
  • Both require many of the same tools
    • Difference is often features/capabilities of software
    • Better documentation and automation

Pg 305

manual site survey toolkit
Manual Site Survey Toolkit
  • Floor Plan
  • Spectrum Analyzer
  • Access Points
  • Client Device
  • Battery packs/Extension Cords
  • Antennas
  • Temporary Mounting Hardware
  • Measuring Device (Tape or Wheel)
  • Digital camera
  • Pens, Paper, Pencil
  • Ladder
  • Cart

Pg 306

performing a predictive site survey
Performing a Predictive Site Survey
  • Done without on-site survey
  • Can use commercial software
    • Sometimes functions are built in to wireless LAN Controller/Switch
  • Often called “Virtual” site surveys because they are performed off-site with computer-aided modeling software. Software predicts how RF signals will travel from each AP.
  • Require the use of imported vector or raster graphics
  • Use databases of loss values for RF obstacles such as doors, walls, and windows
  • Can accurately predict where to place APs for best coverage/throughput
  • Output information is only as good as input information (it’s a computer after all)
  • When used in concert with a manual site survey, accuracy is significantly improved

Pg 308

performing a predictive site survey1
Performing a Predictive Site Survey
  • Cant take into account interference from existing sources

Pg 308

protocol analysis
Protocol Analysis
  • Often used for wired networks
  • Many tools available
  • Watches all wireless frames to let you view details and do analysis
  • Used to
    • Troubleshoot network problems
    • Gather security information
    • Optimize performance

Pg 308

protocol analysis1
Protocol Analysis
  • Can help locate
    • Access points
    • Ad-hoc networks
    • Wireless bridges
    • Mesh Networks
    • Client Devices

Pg 308

documenting existing network characteristics
Documenting Existing Network Characteristics
  • Understanding current infrastructure is important
  • What frequency range will the new WLAN work on?
  • Are there any existing LANs in RF space?
  • Will all or part of the existing WLAN be utilized in new deployment?
  • What effect will the neighboring wireless networks have on the deployment?

Pg 318

rf coverage requirements
RF Coverage Requirements
  • Size of area
  • Number of users
  • Obstacles
  • Signal Propagation
  • RF range
  • Bandwidth requirements of applications
  • Frequency Band of WLAN hardware

Pg 318

infrastructure hardware selection and placement
Infrastructure Hardware Selection and Placement
  • Survey helps determine location of hardware based on
    • RF Coverage
    • Bandwidth
    • Aesthetics
    • Applications
    • Cell Overlap
    • Channel Reuse

Pg 320

infrastructure connectivity and power requirements
Infrastructure Connectivity and Power Requirements
  • Need to know the existing wired infrastructure
    • Distribution
  • Power availability
    • POE is an option

Pg 320

received signal strength
Received Signal Strength
  • Goal is two way communications
  • Reliable connectivity
  • Receiver must have enough signal to determine what was sent
  • Use the received Signal strength to show the amount of power received in a transmission

Pg 321

received signal strength1
Received Signal Strength
  • Amount of received signal strength required is affected by type of applications and RF noise
    • Noise is interference
  • Signal to Noise Ration (SNR) is difference between signal and noise floor
    • Signal is -65dBm and noise floor is -95dBm
      • SNR is 30 dB

Pg 321

antenna use considerations
Antenna Use Considerations
  • Omnidirectional
    • Dipole
  • Semidirectional
    • Patch
    • Panel
    • Sector
    • Yagi
  • Highly Directional
    • Parabolic

Pg 323

testing multiple antenna types
Testing Multiple Antenna Types
  • During Survey, you may want to try and document different antennas
  • Aesthetics can affect choice
  • Other site requirements

Pg 323

channel architectures
Channel Architectures
  • Two main architectures
    • Multiple Channel
      • APs are set to different channels that don’t overlap to minimize interference
      • Can be manually set or automatically chosen
    • Single Channel
      • Fairly New technology
      • Controller can manage all APs in same channel
        • Not everyone transmits at same time

Pg 325

single channel architecture sca
Single Channel Architecture (SCA)
  • Stacking, Spanning, Blanketing
    • Each floor in a building has a channel

Pg 326

installation limitations
Installation Limitations
  • May be limited in where you can install APs
  • May be limited in antenna choice
    • Mounting
    • Cabling
    • Aesthetics
    • Height
  • Ethernet/POE
    • Max cable run

Pg 326

site survey report
Site Survey Report
  • Typically a Microsoft Word or Adobe PDF formatted document that includes:
    • AP locations, configurations, and mounting considerations
    • Documentation exported from a predictive or manual RF Site Survey software tool
    • Deployment recommendations
exam essentials2
Exam Essentials
  • Understand the need for an RF spectrum analysis and how to locate sources of interference.
    • Know that an RF spectrum analysis will allow you to "see" RF in an area proposed for a wireless LAN. Identify different types of RF interference that can have an effect on a wire­less network.
  • Know the differences between manual and predictive site surveys.
    • Know that a manual site survey typically requires a complete walkthrough and testing throughout the proposed area where a wireless LAN will be deployed. A predictive site survey may require minimal time on-site and is a software-based analysis solution.
  • Identify two different types of manual site surveys.
    • Know that manual site surveys can be passive or active and the differences between each.
exam essentials3
Exam Essentials
  • Know how a protocol analyzer can be used as part of wireless LAN site survey.
    • Explain how a wireless protocol analyzer can be used to help identify existing wireless networks and how they may have an impact on the site survey.
  • Understand the importance of identifying existing wireless networks.
    • Know the impor­tance of existing wireless networks and how they may have an effect on a new wireless LAN deployment.
  • Be familiar with the limitations of placement regarding wireless infrastructure devices.
    • Explain some of the limitations regarding placement of wireless LAN devices, including access points, bridges, and antennas.
  • Understand the factors regarding proper antenna use.
    • Identify the different uses of anten­nas based on the customer requirements and characteristics of the environment.
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