CWNA Guide to Wireless LANs, Second Edition 1

Planning for a Wireless Network

• “If you fail to plan, then you plan to fail”• Some steps involved in planning wireless

networks similar to planning wired network– Many steps significantly different

• Basic planning steps: – Assessing needs– Weighing benefits– Calculating costs

CWNA Guide to Wireless LANs, Second Edition 2

Assessing Needs: Reviewing the Current Network (continued)

Table 6-1: Current network table

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Assessing Needs: Reviewing the Current Network (continued)

Figure 6-1: Network diagram

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Determining Benefits

• Hard Benefits• Soft Benefits

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Calculating Return on Investment

• Intel Corporation’s wireless LAN model:– Implement a pilot– Develop a report– Assemble data– Calculate ROI

Table 6-2: Three-year WLAN costs and benefits

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Designing the Wireless LAN

• Involves determining:– Which deployment scenario is best– Which IEEE wireless network standard should be

used– Type of AP management to implemented– Where wireless devices should be located

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Determining the Location of the Wireless Devices

Table 6-3: Interference by objects

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Ad Hoc Mode

Figure 6-3: Ad hoc hidden node problem

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Infrastructure Mode

Figure 6-4: Interference from using same channel

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Infrastructure Mode (continued)

Figure 6-5: Channel reuse

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Infrastructure Mode (continued)

Figure 6-6: Flip flop between access points

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Deploying a Wireless Network

• If planning/designing done correctly, deploying can be easiest step

• Must consider actual placement of APs– Place APs exactly where they were designed to go– To avoid interference, better to place APs higher

• Be careful if placing APs in plenums• If needed, can use PoE

• Good idea to configure WLAN on own network segment

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Providing User Support

• Training• Support

CWNA Guide to Wireless LANs, Second Edition 14

What is a Site Survey?

• Design goals for a site survey:– Achieve best possible performance from WLAN– Certify that installation will operate as promised– Determine best location for APs– Develop networks optimized for variety of

applications– Ensure coverage will fulfill organization’s

requirements– Locate unauthorized APs

CWNA Guide to Wireless LANs, Second Edition 15

What is a Site Survey? (continued)

• When to perform a site survey:– Before installing a new wireless network– Before changing an existing wireless network– When there are significant changes in personnel– When there are changes in network needs– After making physical changes to a building

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Site Survey Tools: Wireless Tools

Figure 7-1: Adjusting AP power levels

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Site Survey Tools: Wireless Tools (continued)

Figure 7-2: External antenna connectors

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Site Survey Tools: Measurement Tools

Figure 7-3: Full-featured site survey analyzer software setup

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Site Survey Tools: Measurement Tools (continued)

Figure 7-4: Full-featured site survey analyzer software results

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Site Survey Tools: Measurement Tools (continued)

Figure 7-6: Basic site survey analyzer software results

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Site Survey Tools: Measurement Tools (continued)

Figure 7-8: Spectrum analyzer

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Site Survey Tools: Documentation Tools

Figure 7-9: Sample site survey form

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Performing a Site Survey: Gathering Data

• Obtaining Business Requirements• Defining Security Requirements• Gathering Site-Specific Documentation• Documenting Existing Network

Characteristics

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Performing a Site Survey: Performing the Survey

Figure 7-10: Position of APs

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Performing a Site Survey: Performing the Survey (continued)

Figure 7-11: Coverage pattern

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Performing a Site Survey: Performing the Survey (continued)

Figure 7-12: Data rate boundaries

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Performing a Site Survey: Creating the Site Survey Report

Figure 7-13: Table of measurements

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Performing a Site Survey: Creating the Site Survey Report (continued)

Figure 7-14: Data rate coverage map

CWNA Guide to Wireless LANs, Second Edition 29

Performing a Site Survey: Creating the Site Survey Report (continued)

Figure 7-15: 3-D signal-to-noise ratio plot