Quiz Questions

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Quiz Questions

• What is Ad-Hoc?
• What is an AP?
• What is a MAN?
• What is ESS?
• Name two devices that can cause interference on a
  wireless network?
• Name two non-routable IP address?
• What is a free utility for doing site surveys?
• What is a default gateway?

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CH 4

• Quiz And H.W.
• Lecture
• Lab
• NIC Set-up
• Out to WEB

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RF In Wireless

• An AP is a Transceiver
• It operates at the 2.4Ghz band of the Radio
  Frequency Spectrum.
• Low power, super high frequency (microwave)
• Transceivers transmit and receive RF (Radio
  Frequency) energy

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Radio Frequency

• Refers to the electromagnetic field that is
  generated when an alternating current is input to
  an antenna.
• Can be used for wireless broadcasting and
  communications over a significant portion of the
  electromagnetic radiation spectrum

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Radio Frequency cont.

• from about 9 kilohertz (kHz) to thousands of
  gigahertz (GHz)
• This portion is referred to as the RF Spectrum
• As the frequency is increased beyond the RF
  spectrum
• electromagnetic energy takes the form of infrared
  (IR)

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Radio Frequency cont.

• visible light
• ultraviolet (UV)
• X rays
• gamma rays
• Many types of wireless devices make use of RF
  fields
• radio, television, cordless and cellular
  telephones, satellite communication systems, and
  many measuring and instrumentation systems used
  in manufacturing.

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IR

• Visible light frequencies
• Used by
• remote control boxes
• cordless mice
• Palm, and other PDAs

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Where is 2.4Ghz?
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This may help!

• The RF spectrum is divided into several ranges,
  or bands. Each of these bands, other than the
  lowest frequency segment, represents an increase
  of frequency corresponding to an order of
  magnitude (power of ten).

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Where is 2.4Ghz?
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8 Bands

• This chart at the bottom of the page depicts the
  eight bands in the RF spectrum, showing frequency
  and bandwidth ranges.

802.11bg
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Antennas
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RF is Manipulated with Antennas

• Antennas control signal pattern and power.
• Done through
• Size
• Shape
• Power
• Materials

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Antenna Radiation Patterns
Horizontal Plane Yagi Slice
Horizonal Plane Bread Slice Pannel, Low backend
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Antenna Radiation Patternscont
Yagi Few Elements, More elements the cleaner it
gets Not as Clean
Yagi
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AP Power

• Typical AP transmits between 50 to 300 milliwatts
• Wireless PC cards USB adapters transmit 50
  milliwatts or less
• A 2400 MHz - 1/10 watt signal will travel up to
  20 miles or less than 20 inches depending on
  antenna design, placement and terrain
• Milliwatt one thousandth of a watt

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Cisco Aironet 350

• 100 mW Radio
• Read Product Data Sheets!!

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Linksys WAP 11 ver 2.6

• 100 mW Radio
• You can push it up to almost 300mW
• Enterprise AP????

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Terrain Survey

• Before choosing an antenna do a survey!!!
• Trees, hills, mountains, buildings
• Not always what you can see but where RF will go
• Beware.. Trees grow!
• Geographic Information Systems GIS

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Terrain Survey cont.

• Attenuation by rain, fog smoke (limited effect,
  but important)
• Remember conditions change, and things move!
• City development plans.
• Plan Ahead!!!

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GIS with Topo
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GIS TOPO
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Line of Site????
From City Hall Roof
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1.23735 miles
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Local Codes Ordinances

• Regulate the placement of antennas.
• Antennas higher than the roof line are regulated
  in most urban areas.
• Antennas masts and towers have very strict
  regulations.
• Some home owner associations and business
  associations have additional restrictions.

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Local Codes Ordinances cont.

• Check before you install.
• Maintain your customer base by following the
  rules.
• RF causes interference in other electronic
  devices
• You may be required resolve interference
• Analog devices are more susceptible

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Local Codes Ordinances cont.

• First come first serve. If you create the
  interference its your responsibility to solve
  it!!!!!

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RF is potentially hazardous to humans and
animals.

• RF from an 802.11b device is more hazardous than
  RF produced by CB radio at the same wattage
• Federal Band on 30 MHz and its harmonics (300,
  3000). These frequencies resonate with human
  organs. These frequencies are used for weapons
  development.

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RF is potentially hazardous to humans and
animals.cont.

• Avoid using damaged or modified equipment
• Use of RF amplifiers requires special FCC
  approval

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• Antenna Types

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Parabolic dish

• directional
• narrow pattern
• high gain- long distance point-to point)

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Yagi antenna

• Directional
• Enclosed
• narrow pattern
• high gain
• point-to-point

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Panel antenna

• semi-directional
• Medium to low gain

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Vertical antenna

• omni directional
• medium low gain

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Connectors

• Connector Conspiracy!!!
• Nothing matches!!!
• Antenna manufactures tend to use standardized
  connections
• Pre-assemble systems before final installation to
  avoid connector conflicts

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COAX

• Coax antenna cables
• Keep them short (line loss)

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Coax cont.

• Consume distances with CAT5 not coax antenna
  cable
• Resolve some 120AC connection problems with
  devices that supply power-over-Ethernet
• Getting CAT5 to exterior of a building can be
  difficult. Consult Universal Building Codes
  (UBC), and local building codes
• Order pre-assembled cables carefully or learn how
  to build your own

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Masts Towers

• Use buildings for elevation 1st
• In many cases increasing antenna height will
  improve signal strength
• Lighting protection (required by code)
• Serviceability (what goes up must come down for
  repair and service)
• Stay off the tower. Hire a State licensed
  contractor
• Wind rating

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FCC Federal Communication Commission

• FCC Notice Whenever changing, replacing or
  installing, amplifiers, antennas, cables or
  additional components not part of the OEM 802.11
  product the installer must understand and follow
  the requirements of FCC part 15. Download a copy
  of Part15 from the FCC website for detailed
  information.

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What we do with antennas!
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First attempt!

• Wireless Weather Station

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Final Result
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QUIZ

• Antennas transmit and receive AC voltage. True
  or False
• 2400 MHz is the same frequency as 2.4 GHz. True
  or False
• The FCC regulates Universal Building Codes True
  or False
• RF stands for Radio Field True or False
• Line Loss refers to attenuation of signal in coax
  cable True or False

• 6. Which type of antenna is best to form a
  wireless bridge between two buildings 200 ft
  apart?
• Bridge antenna
• Dome antenna
• Panel antenna
• Parabolic Dish

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QUIZ cont.

• 7.What portion of the spectrum has been in use in
  the computer world over 10 years?
• 8. How many bands in the RF spectrum?
• 9. List 3 types of antennas.

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Homework

• Read Antenna_Basics_Cisco or Week 3 Reading
• On Web Site
• Write one page bullits on Cisco Paper
• NO LATE HOMEWORK