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CWNA Guide to Wireless LANs Unit 1
Chapters 1-4
106
Computer Networking
Undergraduate 2
02/13/2012

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Term
XP
Definition
Beginning with Windows ____, all Microsoft desktop operating systems recognize a wireless NIC without the need for any external software drivers.
Term
50
Definition
Most industry experts recommend one access point for no more than ____ users if they are performing basic e-mail, light Web surfing, and occasionally transferring medium-sized files.
Term
through the unused wires in a standard unshielded twisted pair (UTP) Ethernet cable
Definition
How does an access point receive electrical power if it is mounted in a location that is not close to an electrical outlet?
Term
FCC
Definition
serves as the primary regulatory agency for wireless communications in the United States and its territorial possessions
Term
NIC
Definition
device that connects the computer to the network so that it can send and receive data
Term
wireless gateway
Definition
device that combines wireless management and security in a single appliance
Term
flash memory
Definition
type of solid-state (microchip) storage technology in which there are no moving parts
Term
de facto standard
Definition
common practices that the industry follows for various reasons, ranging from ease of use to tradition to what the majority of the users do
Term
mini PCI
Definition
small card that is functionally equivalent to a standard PCI expansion card
Term
de jure standards
Definition
standards that are controlled by an organization or body that has been entrusted with that task
Term
bridge
Definition
device that is used to connect two network segments together
Term
IEEE
Definition
world’s largest technical professional society with members around the globe
Term
Project 802
Definition
What is the name for the computer network architecture standards developed by the IEEE?
Answer
Term
802.16
Definition
Which IEEE committee establishes standards for wireless wide area networks?
Term
115
Definition
The 802.11b standard can support wireless devices that are up to ____ meters apart.
Answer
Term
diffused infrared
Definition
The IEEE 802.11 standard outlines the use of ____ transmissions for WLANs.
Term
bridges
Definition
Remote wireless ____________________ are ideal solutions for connecting sites such as satellite offices, remote campus settings, or temporary office locations when the sites are separated by obstacles such as bodies of water, freeways, or railroads that make using a wired connection impractical or very expensive.
Term
True
Definition
CF cards consist of a small circuit board that contains flash memory chips and a dedicated controller chip
Term
they can open domestic markets in larger countries to overseas competition
Definition
What is a disadvantage of standards?
Term
RJ-45
Definition
An access point has a(n) ____ wired network interface that allows it to connect by cable to a standard wired network
Term
True
Definition
The IEEE 802.11g draft was a compromise based on input from several different chip (microprocessor) manufacturers, who had a major stake in the outcome
Term
Wi-Fi Zone
Definition
When a business is registered as a ____ they are qualified be placed in an online database of wireless hotspot locations
Term
ceiling
Definition
Access points are typically mounted on a(n) ____________________ to reduce interference from surrounding objects.
Term
False
Definition
Only one type of wireless NIC is available for laptop computers.
Term
client network adapter
Definition
What is another name for a NIC?
Term
de facto
Definition
Microsoft Windows has become the ____ standard operating system today for personal desktop computers and network servers.
Term
non-root mode
Definition
If a remote wireless bridge is set to ____, it can only transmit to another bridge in root mode
Term
point-to-multipoint
Definition
Which type of remote wireless bridge connection is used to connect multiple LAN segments together?
Term
450
Definition
The radio frequency spectrum is divided into ____ different sections or bands
Term
90
Definition
A loss of 10 decibels means that ____ percent of the power has been lost in mW.
Term
Gain
Definition
____ can occur intentionally from an external power source that amplifies the signal, or unintentionally when an RF signal bounces off an object and combines with the original signal to amplify it.
Term
100
Definition
The maximum EIRP for IEEE 802.11b WLANs is ____ mW.
Term
True
Definition
Highly-directional antennas are generally concave dish-shaped devices.
Term
Frequency
Definition
____ modulation changes the number of waves representing one cycle.
Term
high-gain
Definition
A ____ dipole antenna produces a flatter signal than a standard dipole antenna
Term
radio
Definition
Which of the following types of wave is imperceptible?
Term
current
Definition
The term ____ describes the rate of electrical flow.
Term
False
Definition
A basic rule of thumb is that each 6 dB increase in EIRP results in a quadrupling of the transmission range (distance from the antenna), and a 6 dB reduction in EIRP translates into reducing the range by four
Term
False
Definition
Whenever a wave completes its trip and returns back to the starting point it has finished two cycles.
Term
impedance
Definition
Resistance is measured in ohms and the total amount of resistance is called the ____________________.
Term
antenna
Definition
A(n) ____________________ is a copper wire or similar device that has one end up in the air and the other end connected to the ground or a grounded device.
Term
Voltage Standing Wave Ratio
Definition
Which type of RF loss is caused by the equipment transmitting the signal?
Term
decibels
Definition
RF power gain and loss on a relative scale are measured in ____________________ instead of mW
Term
Ellipsoidal
Definition
What is the shape of a Fresnel zone?
Term
refraction
Definition
When an RF signal moves from one medium to another of a different density the signal actually bends instead of traveling in a straight line. This is known as ____.
Term
modem
Definition
When a digital signal needs to be transmitted over an analog medium, such as when a computer needs to send digital signals over an analog telephone line or TV cable, a device known as a(n) ____ is used.
Term
electrical power
Definition
voltage multiplied by the current
Term
oscillating signa
Definition
up-and-down wave
Term
polarization
Definition
orientation of the radio waves as they leave the antenna
Term
frequency
Definition
rate at which an event occurs
Term
diffraction
Definition
bending caused by an object in the path of the transmission
Term
modulation
Definition
changes to a signal that can be made to enable it to carry information
Term
voltage
Definition
equal to current times resistance
Term
loss
Definition
negative difference in amplitude between signals
Term
scattering
Definition
occurs when the RF signal comes in contact with elements in the air, such as rain or heavy dust particles
Term
True
Definition
In a wireless transmission data travels on invisible radio waves.
Term
Gain
Definition
____________________ is defined as the positive difference in amplitude between two signals.
Term
it does not reveal what the loss is in relation to the whole
Definition
What is a problem with measuring RF loss using a linear scale?
Term
186,000 miles
Definition
Electromagnetic waves travel freely through space in all directions at the speed of light, or approximately ____ per second.
Term
digital
Definition
A(n) ____________________ signal has numerous starts and stops throughout the signal stream.
Term
Highly-directional
Definition
____ antennas are used for long distance, point-to-point wireless links, such as connecting buildings that are up to 42 kilometers (25 miles) apart.
Term
hertz
Definition
Which of the following units is used to measure frequency?
Term
frequency shift keying
Definition
Which digital modulation technique is similar to frequency modulation?
Term
80
Definition
What is the free space loss (in dB) for IEEE 802.11b and 802.11g WLANs when the distance in meters is 100?
Term
AM
Definition
Television uses three types of modulation. The video portion uses ____.
Term
1/4 of
Definition
The length of an antenna should be about ____ the wavelength.
Term
Vertical
Definition
____ polarization is typically used in wireless LANs with the dual antennas of access points pointing upward.
Term
chipping
Definition
DSSS uses a bit pattern called a ____ code.
Term
noise level
Definition
Narrowband transmissions require significant power for the signal to be transmitted because the signal must exceed the ____________________, or the total amount of outside interference, by a substantial margin.
Term
dwell
Definition
The amount of time that a transmission occurs on a specific frequency is called the ____________________ time.
Term
between 10 and 20 Mbps
Definition
Because a device must wait to transmit until it receives the last reflected signal, this in effect puts a ceiling limit on the overall speed of the WLAN. What is the current ceiling for WLAN speed?
Term
shared wireless access
Definition
The _________________________ Protocol defines a set of specifications for wireless data and voice communications around the home.
Term
Data Link
Definition
IEEE has divided the ____ layer into two sublayers: Logical Link Control (LLC) and Media Access Control (MAC).
Term
PHY and MAC
Definition
Into which layers are WLAN features isolated by IEEE standards?
Term
complementary code keying
Definition
The ____ coding technique consists of a set of 64 8-bit code words.
Term
access point
Definition
Users can upgrade from an 802.11b network to a faster 802.11g network simply by replacing the ____________________.
Term
interference from another radio signal
Definition
What is a disadvantage of narrowband transmissions?
Term
Radio
Definition
____ signals by nature transmit on only one frequency or a very narrow portion of the frequencies.
Term
application
Definition
What is the top layer of the OSI reference model?
Term
400 milliseconds
Definition
According to FCC regulations, all FHSS systems in the 900 MHz band must change frequencies through 50 channels and cannot spend more than ____ on one frequency each 20 seconds.
Term
False
Definition
Increasing the speed of the WLAN will cause shorter delays in waiting for reflections
Term
DSSS
Definition
The Physical Layer Convergence Procedure (PLCP) standards for 802.11b are based on ____.
Term
direct sequence spread spectrum
Definition
uses an expanded redundant code to transmit each data bit
Term
frequency hopping spread spectrum
Definition
uses a range of frequencies that change during the transmission
Term
Forward Error Correction
Definition
transmits a secondary copy along with the primary information
Term
physical layer
Definition
sends signals to the network or receives signals from the network
Term
quadrature phase shift keying
Definition
can double the amount of data encoded over PSK to 250 Kbps per channel, which produces a 12 Mbps (250 Kbps x 48) data rate
Term
transport layer
Definition
ensures that error-free data is given to the user
Term
channel bonding
Definition
two channels are combined (one for sending data and the other for receiving) to provide the necessary frequency for the higher speeds
Term
orthogonal frequency division multiplexing
Definition
sending multiple signals at the same time
Term
network layer
Definition
picks the route packets take and handles addressing of packets for delivery
Term
14
Definition
The 802.11b standard specifies ____ frequencies that can be used, beginning at 2.412 GHz.
Term
Synchronization
Definition
The ____ field of an 802.11a frame consists of 10 repetitions of a short training sequence signal and two repetitions of a long training sequence signal.
Term
79
Definition
Bluetooth divides the 2.4 GHz frequency into ____ different frequencies spaced 1 GHz apart.
Term
False
Definition
Of the 52 subchannels, 32 are used for standard transmissions and 20 are used for FEC transmissions.
Term
turbo
Definition
Although 54 Mbps is the “official” top speed of 802.11a, the IEEE specification also allows for higher speeds. These higher speeds are known as ____________________ mode or 2X mode.
Term
Channe
Definition
____ is not part of a frame.
Term
10
Definition
When using the Shared Wireless Access Protocol, devices can be as far as 45 meters (150 feet) apart and can send and receive data at rates up to ____ Mbps.
Term
DSSS
Definition
Which system is preferred for 802.11b WLANs?
Term
True
Definition
The value of layers in the OSI reference model is that it divides networking into a series of tasks, and then illustrates how those tasks relate to each other.
Term
hop
Definition
In FHSS, the amount of time needed to move from one frequency to another is the ____ time.
Term
during World War II
Definition
When was the concept used by FHSS technology developed?
Term
False
Definition
When transmitting with FHSS, if interference is encountered on a particular frequency then that part of the signal will be retransmitted on the previous frequency of the hopping code.
Term
signals are broken up and the parts are sent in parallel
Definition
How does OFDM work?
Term
True
Definition
Because wireless technology has advanced at such a rapid pace, the earliest WLANs are now essentially obsolete.
Term
session
Definition
Which layer of the OSI reference model permits the devices on the network to hold ongoing communications across the network?
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