Performing a wlan site survey
This presentation is the property of its rightful owner.
Sponsored Links
1 / 51

Performing a WLAN Site Survey PowerPoint PPT Presentation


  • 112 Views
  • Uploaded on
  • Presentation posted in: General

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

Download Presentation

Performing a WLAN Site Survey

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


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 analysis

RF Spectrum Analysis

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 analysis2

RF Spectrum Analysis

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 interference2

Wi-Fi Interference


Wi fi interference3

Wi-Fi Interference


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


Protocol analysis2

Protocol Analysis

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


Received signal strength2

Received Signal Strength

Pg 322


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.


  • Login