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Wireless Networking WLAN Site Survey Module-09

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Title: Wireless Networking WLAN Site Survey Module-09


1
Wireless Networking WLAN Site Survey Module-09
  • Jerry Bernardini
  • Community College of Rhode Island

2/13/2013
1
Wireless Networking J. Bernardini
2
Presentation Reference Material
  • CWNA Certified Wireless Network Administration
    Official Study Guide
  • (PWO-104), David Coleman, David Westcott,
    2009, Chapter-15,16
  • CWNA Certified Wireless Network Administration
    Official Study Guide, Fourth Edition, Tom
    Carpenter, Joel Barrett
  • Chapter 6, pages 232-318
  • The California Regional Consortium for
    Engineering Advances in Technological Education
    (CREATE) project

2/13/2013
Wireless Networking J. Bernardini
2
3
What is a Site Survey?
  • Process of planning a WLAN to meet design goals
  • When installing a WLAN for an organization, areas
    of dead space might not be tolerated
  • Ensure blanket coverage, meet per-user bandwidth
    requirements, minimize bleeding of signal
  • Factors affecting wireless coverage goals
  • Devices emitting RF signals
  • Building structure (walls, construction
    materials)
  • Open or closed office doors
  • Stationary versus mobile machinery/equipment
  • Movement of mobile walls (e.g., cubicles)

4
What is a Site Survey?
  • Factors affecting wireless coverage goals
    (continued)
  • Expansion of physical plant or growth of
    organization
  • Existing WLANs
  • Both inside organization, and within nearby
    organizations
  • Site survey Process of planning a WLAN to meet
    design goals
  • Effectiveness of a WLAN often linked to
    thoroughness of the site survey

5
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 organizations
    requirements
  • Locate unauthorized APs

6
More Site Survey Goals
  • Map nearby wireless networks to determine
    existing radio interference
  • Reduce radio interference as much as possible
  • Make wireless network secure
  • Survey provides realistic understanding of
    infrastructure required for proposed wireless
    link
  • Assists in predicting network capability and
    throughput
  • Helps determine exact location of APs and power
    levels required

7
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

8
Project Planning Overview
  • Users Requirements
  • Budget Population
  • Applications Performance
  • Security Coverage Area
  • Physical Logical Network Site Environment

9
Site Survey
  • A site survey is very important before you
    deploy a wireless network.
  • A site survey involves analyzing a site from an
    RF perspective.
  • Coverage
  • Interference Sources
  • Equipment Placement
  • Power Requirements
  • Wiring Requirements

10
Preparing for a Site Survey
  • Preliminary Plan
  • Existing Network
  • Towers and Roofs
  • Coverage
  • Access Point Locations
  • Security

11
Facility Analysis
  • What type of Facility?
  • Personal
  • Small Office Home Office, (SOHO)
  • Real-estate Office
  • Small Warehouse
  • Hospital
  • Manufacturing Plant
  • Corporate or Educational Campus

12
Physical and RF Site Surveys
  • Two major categories of site surveys
  • Physical Survey and RF Survey
  • Physical Survey
  • Examination of physical environment
  • RF Survey
  • Examination of RF activity

13
Questions Answered by Physical Site Surveys
14
Questions Answered by RF Site Survey
15
Manual RF Site Survey Breakdown
16
Obtaining Business Requirements
  • Determine business reasons why WLAN being
    proposed or extended
  • If this step skipped, almost impossible to
    properly design and implement the network
  • Primary data gathering method is interviewing
  • Must determine type of mobility required within
    organization
  • Must determine per-user bandwidth requirements
  • May be different types of users with different
    bandwidth requirements

17
Overall Business Objectives
  • Quality improvement (Better)
  • Efficiency improvement ( Faster)
  • Cost reduction (Cheaper)
  • Increased production (More)
  • Organizational continuity (Continue to exist)
  • Sarbanes-Oxley (accountability)

18
Organizations Needs and Objectives
  • Determine business requirements
  • User requirements-bandwidth related
  • Functional requirements
  • Budgetary Constraints
  • Regulatory Constraints

19
Site Survey Tools Wireless Tools
  • Most basic tool is AP itself
  • Position AP in various locations, monitor signal
    as you move
  • APs should have ability to adjust output power
  • APs should have external antenna connectors
  • Test effectiveness of different antenna types in
    different situations
  • May need DC-to-AC converter for testing
  • Notebook computer with wireless NIC also
    essential for testing
  • Previously configured and tested

20
Site Survey Tools Measurement Tools
  • Site Survey Analyzers Specifically designed for
    conducting WLAN site surveys
  • Software often built into AP
  • Receive Signal Strength Indicator (RSSI) value
  • Full-featured site survey analyzer software
    settings
  • Destination MAC Address
  • Continuous Link Test
  • Number of Packets
  • Packet Size
  • Data Retries

21
Site Survey Tools Measurement Tools (continued)
  • Site Survey Analyzers (continued)
  • Full-featured site survey analyzer software
    settings (continued)
  • Data Rate
  • Delay Between Packets
  • Packet Tx Type
  • Unicast or multicast
  • Percent Success Threshold
  • Basic survey analyzer software contains far fewer
    features

22
Spectrum Analyzers
  • Scan radio frequency spectrum and provides
    graphical display of results
  • Typically measure signal-to-noise ratio
  • Single-frequency analyzers measure
    signal-to-noise ratio at specified frequency
  • Helpful in identifying interference problems
  • Thus, helps properly position/orient AP
  • Costly 500 50,000

23
Spectrum Analyzer Measures RF energy
Frequency range 100kHz - 6 GHz. Internal
preamplifier with frequency range from 100 kHz -
6 GHz. Displayed average noise level typ. -135
dBm (RBW 100 Hz). 0.5 dB typ. level accuracy up
to 6 GHz. Resolution bandwidths 100 Hz - 1 MHz, 1
and 3 steps. Wide range of detectors sample,
max/min peak, auto peak, RMS. Cost 13,500
24
WiFi Hopper
Website http//wifihopper.com/overview.html
25
Airmagnet Site Survey Tool
2/13/2013
Wireless Networking J. Bernardini
25
26
AirMagnet Survey
  • AirMagnet Survey This WLAN planning solution
    stands apart from other market planning solutions
    by enabling enterprises to collect live signal,
    packet and spectrum data during their site
    surveys. This allows enterprises to simulate and
    measure network performance in the most
    scientific way possiblewith the most accurate
    depiction of a real-world user experience-which
    ultimately results in a better performing
    network.

2/13/2013
Wireless Networking J. Bernardini
26
27
Site Survey Tools Documentation Tools
  • Create a hard copy of site survey results
  • Make available for future reference
  • No industry-standard form for site survey
    documentation
  • Site survey report should include
  • Purpose of report
  • Survey methods
  • RF coverage details (frequency and channel plan)
  • Throughput findings
  • Sources of interference

28
Site Survey Report Material
  • Site survey report should include (continued)
  • Problem zones
  • Marked-up facility drawings with access point
    placement
  • Access point configuration
  • Use plain paper and building layout blueprints as
    tools
  • Advisable to create database to store site survey
    information and generate reports

29
Survey Security and Site Documents
  • Defining Security Requirements Consider type of
    data encryption and type of authentication that
    will take place across WLAN
  • Consider existing security policies and
    procedures
  • Gathering Site-Specific Documentation
  • Blueprints, facility drawings, and other
    documents
  • Show specific building infrastructure components
  • Inspecting the site
  • Document changes to blueprints and get visual
    perspective
  • Behind-the-scenes site inspection
  • Documenting Existing Network Characteristics New
    or expanded WLAN will dovetail into network
    already in place
  • Determine degree to which WLAN will interact with
    other wired networks
  • Legacy systems may require additional equipment
    to support WLAN

30
Performing a Site Survey Performing the Survey
  • Collecting RF Information
  • Note objects in and layout of room
  • Use digital camera
  • Position AP
  • Initial location will depend on antenna type
  • Document starting position of AP
  • Using notebook computer with site survey analyzer
    software running, walk slowly away from AP
  • Observe data displayed by analyzer program
  • Data rate, signal strength, noise floor, and
    signal-to-noise ratio

31
Position of APs
32
Collecting RF Information
  • Continue moving until data collected for all
    areas
  • Data collected used to produce
  • Coverage pattern Area where signal can be
    received from the AP
  • Data rate boundaries Range of coverage for a
    specific transmission speed
  • Throughput Number of packets sent and received
    and data rates for each
  • Total transmission range Farthest distance at
    which signal can be received by wireless device

33
Survey Data rate boundaries
34
RF Data Collection
  • Collecting Non-RF Information
  • Sources of interference can include
  • Wire mesh security windows, Aquariums, Outer
    walls, Ceramic or marble floors, Concrete floors
    or pillars, Security booth bullet-proof glass,
    Mirrors, and Elevator shafts or filing cabinets
  • Electrical and network connections
  • Outdoor Surveys Similar to indoor surveys, but
    must consider climatic conditions, trees,
    different possibilities for antenna positions

35
Performing a Site Survey Performing the Survey
  • Outdoor Surveys (continued)
  • Different tools may be required
  • GPS
  • Range finder
  • Tape measure
  • Lighting beacons, flares, and spotlights
  • Finalizing the Survey Documents Final result is
    map of optimal areas of coverage for placement of
    access point
  • If results unacceptable, must relocate AP and
    start over

36
Creating the Site Survey Report
  • Narrative section
  • State customer requirements
  • Outline methodology
  • Outline all steps taken during survey
  • Clearly state results of measurements
  • May have tables of measurements
  • Recommendations
  • Should always address security
  • Graphic section
  • Generally includes maps and diagrams of coverage
    area
  • Data rate coverage map
  • Signal-to-noise ratio plot

37
Table of measurements
38
Data rate coverage map
39
3-D signal-to-noise ratio plot is the output of
some survey applications
40
Preparing for a Site Survey
  • Facilities Analysis (Floor Plan, Maps, Satellite
    Imagery)

Satellite or Ariel Imagery
Floor Plan Network
WLAN
Naming Convention
Santa Maria,SM
BLDG-A
BLDG-B
Maps of Campus/Facilities
wlan-sm-bldga-rm12ap3
RM-12-AP3
RM-12-AP4
RM-10-AP2
41
Existing Networks
  • Is there already a network in place?
  • Wired
  • Wireless
  • Wired-Wireless
  • Topology Location of existing equipment
  • Current Users Requirements

42
Area Usage and Towers
  • Indoors, outdoors, or both.
  • Indoor
  • Building Type Floor Plan
  • HVAC Security
  • Outdoor
  • Weather Security
  • Towers Power
  • Environmental Obstructions (RF)

43
Purpose Business Requirement
  • Purpose, Needs, and Expectations
  • Define Business Model
  • User needs
  • Interview with client and users
  • Wireless impact on business operation

44
Bandwidth Roaming
  • Bandwidth and Throughput
  • 802.11 a, b, g, n and Bluetooth
  • Number of Users
  • Types of Applications
  • Environmental changes as a function of
    seasons.
  • Mobility or Roaming needs

45
Available Resources
  • Project Budget
  • Time Line
  • Trained Personnel
  • Floor Plans, CAD
  • Existing Site Survey Reports
  • Access to Equipment and Site Areas

46
Security Requirements
  • Network Security Wired and Wireless
  • Corporate Mandated Security
  • Current Security Policies
  • Hierarchy of Data Security
  • Training of Users

47
Site Survey Equipment
  • Access Point, PC Card, and USB Adaptor
  • Antennas, Cables, and Connectors
  • Desktops, Laptops, and PDAs
  • Power Supplies and Batteries
  • Ladder, Measure, and Hand Tools
  • Analysis Software
  • GPS, Cell Phone, Walkie-Talkie
  • Forms, Floor Plans, and Paper

48
Site Survey Equipment
49
Site Survey Software
Netstumbler - www.netstumbler.com This program is
great for seeing what other access points are
nearby. This can help you by seeing what other
SSID's are around so you know what NOT to name
yours, as well as help you pick a channel that
doesn't have a lot of people using it, giving you
a better signal between your access point and
your client. Works only with certain cards.
Windows and PocketPC versions are
available. Kismet - www.kismetwireless.net This
program is similar to Netstumbler, though for the
open source world. Additional features that
Kismet has include the ability to log any traffic
heard, as well as providing additional detailed
information. Unlike Netstumbler, Kismet is
COMPLETELY passive, meaning no transmitting is
done to obtain any of the information shown.
Great for finding rogue access points as well as
their users in a corporate environment. nix,
Familiar (Linux on iPAQ) and Sharp Zaurus
versions are available.
50
Site Survey Software
Airsnort - airsnort.shmoo.com This program was
used in the early days of 802.11b to determine
whether or not your access point and/or wireless
adapters used insecure initialization values for
the RC4 encryption used by WEP. Many newer AP's
and cards have resolved this by not using the
3000-something weak IV's that could lead to the
WEP key being cracked. nix/X-Windows version
available. Also WPA and WPA2 are now in use.
51
Access Point
Electrical Specifications Using the Power
Adapter Voltage (Input) 100 to 240 VAC (50-60
Hz) _at_ 0.4 A Voltage (Output) 12 VDC Power
Consumption 10 Watts Using Active
Ethernet Input Voltage 42 to 60 VDC Output
Current 200mA at 48V Power Consumption 10
Watts
Recommend 12 volts DC at 1.5 Ampere Power
Source 48 volts DC at 250 mA Power
Source Variable RF power output would be a nice
feature. If not available consider fix or
stepped attenuators.
52
Access Point Remote Power
12 volt, 7-amp/hr recharge in less than 12 hours.
12 volt, 17-amp/hr recharge in less than 12 hours.
53
Laptops PDAs
1
2
4
3
54
Spectrum Analyzer
Two basic types Hardware and Software
55
Network Protocol Analyzer
Wireshark
Fluke
AirMagnet
56
Site Survey Kit Checklist
  • See Site Survey Kit Checklist in the text.
  • Laptop or PDA
  • Wireless PC card and AP as needed.
  • Power Pack
  • Site Survey Software
  • Location maps and building diagrams
  • Cables Connectors
  • Proper Clothing

57
Site Survey Kit Checklist
  • Hand Tools and mounting hardware
  • Digital Camera
  • GPS, Terrestrial Telescope, Binoculars
  • Measuring wheel, tape measure, and level
  • Appropriate transporting equipment
  • Documentation and writing materials
  • Antennas
  • Anything else you meant to bring.

58
Conducting a Site Survey
  • Examine the network usage problems the wireless
    LAN solves.
  • Study blueprints of the proposed wireless LAN
    site.
  • Conduct a physical walk-through and inventory.
  • Measure the radio frequency (RF) transmissions.
  • Indoor and/or Outdoor Survey.

59
Indoor Survey
  • AC Power Outlets and Grounds
  • Wired Network Connectivity
  • Potential RF Obstructions (Metal)
  • Potential Interference Sources
  • Access to all areas

60
Floor Plan
65 feet
42 feet
61
Indoor Survey
65 feet
2
3
42 feet
Utilities and POP
Ethernet
RF Field
1
Gateway
Access Points
62
Outdoor Survey
  • Trees, buildings, lakes, mountains, or other
    obstructions between linked sites.
  • Consider growth and foliage of trees, bushes,
    and plants.
  • Line of Sight and distance between stations.
  • Weather common to location.
  • Towers and roofs.

63
RF Information Gathering
  • Range and Coverage Patterns
  • Data Rate Boundaries
  • Documentation
  • Throughput Test and Capacity
  • Interference Sources
  • Wired Data Connectivity
  • AC/DC Power Requirements
  • Outdoor Antennas

64
Range and Coverage Patterns
Think Three Dimensional!
AP
65
Range and Coverage Patterns
AP
-47 dB
1
-61 dB
AP
AP
2
-61 dB
New Coverage Area
- 61 dB
66
Range and Coverage Patterns
Dead Spot
1
Dead Spot
2
3
Dead Spot
AP
N
Coverage Map
A dead spot is an area or zone where wireless
network services are not available because the
signal between the client and the AP is blocked
or attenuated, usually by terrain, excessive
foliage, buildings, or architectural features.
67
Range and Coverage Patterns
11
6
11
6
1
802.11b/g
11
6
36
44
40
36
48
44
40
802.11a
40
44
48
68
Data Rate Boundaries
AP
5.5 Mbps
2 Mbps
AP
69
Throughput Test Capacity
  • Live testing of the network with actual data
    transfers.
  • Traffic congestion, bottlenecks, and future
    expansion.
  • Document baseline measurements for deliverables,
    (User Requirements) and maintenance and
    troubleshooting.

70
Interference Sources
  • Active Interference 2.4 GHz cordless phones,
    Medical Equipment, Microwave Ovens/sources,
    Bluetooth, X10 Devices, Other 802.11 Devices
  • Passive Interference Path Loss, Metal Walls,
    Concrete, Brick, Stucco, Foliage, Glass, People,
    Vehicles
  • Signal Reflections - Multipath

71
AC/DC Power Requirements
  • Is AC circuit available and at what rating?
  • Is a ground available?
  • Power over Ethernet?
  • Wired Network Connectivity
  • Backup Power

72
Outdoor Antennas
  • Temporary Antennas for a Site Survey.

73
Site Survey Report Format
  • Title Page
  • Abstract
  • Users Requirements
  • RF Coverage Area
  • Throughput
  • Interference Sources
  • Problem Areas
  • Drawings

74
Site Survey Report Format
  • Installation/Configuration Information
  • Cost Analysis
  • Conclusion
  • Appendices

75
Summary
  • A site survey is an in-depth examination and
    analysis of a proposed wireless LAN site to meet
    design goals
  • Three categories of tools used
  • Wireless tools include the access point and
    notebook computers with a wireless NIC
  • Measurement tools include site survey analyzers,
    spectrum analyzers, and network analyzers
  • Documentation tools create a hard copy of the
    site survey results for future reference
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