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25 Cards in this Set
- Front
- Back
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Dominant wireless LAN (WLAN) Technology
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802.11
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What 802 working group creates 802.11 standards?
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IEEE 802.11 Working Group
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How can firms provide WLAN coverage throughout a a large building?
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By placing access points throughout the building.
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Is wireless radio transmission usually expressed in terms of wavelength or frequency?
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Frequency
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Omnidirectional Antennas
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Transmit and receives signals equally well from all directions.
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Dish Antenna
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Focuses on a stronger signal by pointing in a particular direction.
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Under what circumstance would you use an omnidirectional antenna?
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When transmitting between short distances
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Under what circumstances would you use a dish antenna?
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When transmitting between long distances
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What type of antennas are used in WLANs?
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Omnidirectional
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What attenuates more rapidly with distance?
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Radio signals
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Shadow zone (dead spot)
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Caused by an obstruction blocking a direct path between the sender and receiver
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What is the most serious propagation problem in WLANs?
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Multipath interference
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In radio, how can you send different signals without the signals interfering with one another?
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By sending each signal through a different channel.
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Does a signal travel at a single frequency or over a range of frequencies?
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Over a range of frequencies.
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What is channel bandwidth?
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The range of frequencies in a channel.
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What do we call a system whose channels have large bandwidth?
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A broadband channel.
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Do WLANs today use licensed or unlicensed bands?
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Unlicensed
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What is the advantage of using unlicensed bands?
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No need for government approval
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What is the disadvantage of using unlicensed bands?
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No way to stop interference from other nearby users
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In unlicensed bands what type of transmission method is required by regulators
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Spread spectrum transmission (SST)
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Which licensed band is defined the same way in most countries around the world?
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The 2.4 gigahertz band
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If these two waves are out of phase, they will negate each other, giving no signal.
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Direct Wave and Reflected Wave
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The frequency spectrum is divided into two blocks of frequency called?
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Service bands
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The name of a network is called what?
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Service Set ID (SSID)
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Multiuser (Multiple input/ Multiple output) MIMO does what?
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Allows two wireless hosts to transmit at the same time.
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