True/False
Indicate whether the sentence or statement is true
or false.
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1.
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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.
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2.
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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.
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3.
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Increasing the speed of the WLAN will cause shorter delays in waiting for
reflections.
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4.
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Because wireless technology has advanced at such a rapid pace, the earliest WLANs are
now essentially obsolete.
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5.
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Of
the 52 subchannels, 32 are used for standard transmissions and 20 are used for FEC
transmissions.
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Multiple Choice
Identify the
letter of the choice that best completes the statement or answers the question.
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6.
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What
is the top layer of the OSI reference model? a. | application | c. | physical | b. | presentation | d. | transport | | | | |
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7.
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Which
layer of the OSI reference model permits the devices on the network to hold ongoing communications
across the network? a. | presentation | c. | transport | b. | session | d. | network | | | | |
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8.
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____
signals by nature transmit on only one frequency or a very narrow portion of the
frequencies. a. | Broadband | c. | Radio | b. | Computer | d. | Heat | | | | |
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9.
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What
is a disadvantage of narrowband transmissions? a. | requires a complicated
algorithm | c. | expensive to
implement | b. | not well regulated | d. | interference from another radio
signal | | | | |
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10.
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When
was the concept used by FHSS technology developed? a. | during World War
I | c. | in the
1960s | b. | during World War II | d. | in the 1980s | | | | |
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11.
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In
FHSS, the amount of time needed to move from one frequency to another is the ____
time. a. | dwell | c. | lift | b. | switch | d. | hop | | | | |
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12.
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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. a. | 20
milliseconds | c. | 400
milliseconds | b. | 30 milliseconds | d. | 1 second | | | | |
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13.
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Bluetooth divides the 2.4 GHz frequency into ____ different frequencies spaced 1 GHz
apart.
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14.
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DSSS
uses a bit pattern called a ____ code. a. | hopping | c. | dwelling | b. | setting | d. | chipping | | | | |
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15.
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____
is not part of a frame. a. | Length | c. | Channel | b. | Parity | d. | Data | | | | |
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16.
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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? a. | under 10 Mbps | c. | between 20 and 30 Mbps | b. | between 10 and
20 Mbps | d. | over 50
Mbps | | | | |
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17.
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How
does OFDM work? a. | signals are
broken up and the parts are sent in parallel | b. | the same signal
is sent on multiple channels | c. | one signal is sent twice on the same
channel | d. | a signal is sent over a wired network at the same time as the
wireless network | | |
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18.
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Which
system is preferred for 802.11b WLANs? a. | DSSS | c. | OFDM | b. | FHSS | d. | All are equally preferred | | | | |
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19.
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IEEE
has divided the ____ layer into two sublayers: Logical Link Control (LLC) and Media Access Control
(MAC). a. | Physical | c. | Transport | b. | Data Link | d. | Session | | | | |
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20.
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Into
which layers are WLAN features isolated by IEEE standards? a. | PHY and
PMD | c. | PHY and
MAC | b. | MAX and
PLCP | d. | PMD and
PLCP | | | | |
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21.
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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.
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22.
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The
Physical Layer Convergence Procedure (PLCP) standards for 802.11b are based on ____.
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23.
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The
802.11b standard specifies ____ frequencies that can be used, beginning at 2.412
GHz.
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24.
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The
____ coding technique consists of a set of 64 8-bit code words. a. | chipping | c. | Barker | b. | fixed scramble | d. | complementary code keying | | | | |
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25.
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What
techniques are used by vendors to achieve 2x mode for transmissions? a. | combine two
frequency channels | c. | reallocating the
individual carriers | b. | use different coding rate
schemes | d. | All of the
above | | | | |
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26.
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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. a. | Rate | c. | Synchronization | b. | Service | d. | Parity | | | | |
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Completion
Complete each sentence or
statement.
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27.
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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.
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28.
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The
amount of time that a transmission occurs on a specific frequency is called the ____________________
time.
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29.
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The
_________________________ Protocol defines a set of specifications for wireless data and voice
communications around the home.
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30.
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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.
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31.
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Users
can upgrade from an 802.11b network to a faster 802.11g network simply by replacing the
____________________.
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Matching
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Match each term with the correct statement below. a. | physical
layer | f. | direct sequence
spread spectrum | b. | channel bonding | g. | quadrature phase shift keying | c. | frequency
hopping spread spectrum | h. | transport
layer | d. | Forward Error Correction | i. | orthogonal frequency division
multiplexing | e. | network layer | | | | |
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32.
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uses
an expanded redundant code to transmit each data bit
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33.
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uses
a range of frequencies that change during the transmission
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34.
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transmits a secondary copy along with the primary information
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35.
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sends
signals to the network or receives signals from the network
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36.
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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
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37.
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ensures that error-free data is given to the user
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38.
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two
channels are combined (one for sending data and the other for receiving) to provide the necessary
frequency for the higher speeds
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39.
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sending multiple signals at the same time
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40.
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picks
the route packets take and handles addressing of packets for delivery
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Short Answer
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41.
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What
is the Open Systems Interconnection (OSI) reference model?
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42.
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What
is a disadvantage of narrowband transmissions?
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43.
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Describe the FCC restrictions on FHSS.
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44.
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What
are the advantages to using DSSS with a chipping code?
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45.
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How
does OFDM avoid problems caused by multipath distortion?
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46.
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What
are the fields that make up a PLCP frame?
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47.
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There
are two disadvantages to using U-NII. What are they?
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48.
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The
modulation techniques used to encode the 802.11a data vary depending upon the speed. Describe
the techniques used to transmit at 24 Mbps.
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49.
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The
802.11g standard outlines two mandatory modes along with one optional mode. Describe each
mode.
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50.
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What
are disadvantages of the 802.11g standard?
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