Chapter 16 Flashcards

1
Q

Absorption

A

The loss of energy in an
electromagnetic signal as it
passes through a medium.
TDMM.* Page 16-9

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2
Q

AGC

A

Automatic Gain Control
A circuit arrangement used to
automatically sense variations in
the received signal levels and
adjust the gain of the receiver
amplification stages to
provide a constant output.
TDMM.* G-14

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3
Q

Amplitude

A

The size or magnitude of a
voltage or current waveform.
TDMM.* Page 16-6

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4
Q

Access Point (AP)

A

Access Point
Stand-alone hardware device or
a computer wireless adapter
with software that acts as a
wireless communication hub for
users of wireless devices to
connect with each other and to
bridge those devices to the
cabled portion of the network.
TDMM.* Page G-4

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5
Q

BSS

A

Basic Service Set
A single wireless LAN (WLAN)
access point (AP) and its
associated clients, loosely
equivalent to a wireless
collision domain.
TDMM.* Page G-19

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6
Q

DAS

A

Distributed Antenna System
A network of spatially separated
antenna nodes connected to a
common system source via
transport medium that provides
wireless service within a
geographic area or structure.
(HetNet Forum)
TDMM.* Page G-60

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7
Q

Diffraction

A

The bending of sound, radio, or
light waves around an object,
barrier, or aperture edge.
TDMM.* Page 16-9

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8
Q

Dispersion

A

The loss incurred by an RF
signal due to the natural
broadening of the wave front.
TDMM.* Page 16-12

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9
Q

ERRCS

A

Emergency Responder Radio
overage Systems
An implementation of distributed
antenna system (DAS) designed
for use by first responders or
public safety officials. These
systems re-transmit fire and police
radio sianals from outside of a
the building’s interior
allowing for continuous
communication even within
structures whose construction
greatly attenuates outside
radio signals.
TDMM: Page G-68

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10
Q

Extended Service Set
(ESS)

A

Extended Service Set
A collection of access points (APS) that are tied together by a wired backbone in a single collision domain, or by virtual LANs (VLANs) to allow Layer 2 data link layer) roaming.
TDMM.* G-73

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11
Q

Frequency

A

A measure of the rate at which a
periodic function repeats. It is
the number of cycles or events
per unit of time. For
electromagnetic signals,
frequency is expressed
in hertz (Hz).
TDMM.* Page 16-6

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12
Q

IBSS

A

Independent Basic Service Set
A group of stations in a wireless
LAN (WLAN) that communicate
directly with each other (without
the use of a central access point
[AP]). This type of network is
also called an ad hoc network.
TDMM: Page G-95

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13
Q

IR (Standard)

A

Infrared (Standard)
An inexpensive
telecommunications standard
based on the use of the
IR light spectrum.
TDMM: Page 16-66

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14
Q

LoS

A

Line of Sight
The imaginary line that connects
the observer’s eye with the
object the observer is looking at.
TDMM.* G-110

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15
Q

NIC

A

Network Interface Card
The circuitry in a device that
provides the means to connect,
via cabling or wireless to a
network.
TDMM.* Page G-129

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16
Q

OS

A

Operating System
The system software that
controls the execution of all
programs and the use of
resources on a device
such as a computer.
TDMM.* Page G-134

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17
Q

PTP

A

Point to Point
A direct connection established
between two specific locations,
as between two buildings
or devices.
TDMM.* Page G-144

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18
Q

Reflection

A

The abrupt change in direction
of a wave front at the interface
between two dissimilar media
such that the incident wave front
returns into the medium from
which it originated.
TDMM.* Page 16-9

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19
Q

Refraction

A

The abrupt change in direction
of a wave front at the interface
between two dissimilar media as
the incident wave front enters
the second medium.
TDMM.* Page 16-9

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20
Q

QoS

A

Quality of Service
1 .A commitment to
performance, based on
predefined service pararneters.
2.A measure of the level of
service provided on a network.
TDMM: Page G-156

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21
Q

Scattering

A

A change in the level, direction, frequency, or polarization of incident radiation when it encounters small particles or inhomogeneous particles whose size is similar to or smaller than the wavelength of the incident radiation.
TDMM.* Page 16-9

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22
Q

Wavelength

A

The distance between points of
a corresponding phase of one
complete cycle of a wave. In
electromagnetic systems,
wavelength is typically
measured in meters.
TDMM.* Page 16-6

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23
Q

WLAN

A

Wireless Local Access Network
A LAN that functions wirelessly
between the client and a
wireless access point (WAP).
Most modern WLANs are based
on IEEE 802.11 standards,
marketed under the Wi-Fi name.
TDMM.* Page G-209

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24
Q

Name 3 technological
considerations in
wireless design.

A

1 .Scalability of the network
2. Compatibility of the overall network
3. ImpIementation of a wireless network based around standards
TDMM.* Page 16-2

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25
Name 3 factors that define the reliability of a wireless network.
1 .Accessibility 2.Continuity 3.Consistency of service TDMM.* Page 16-3
26
Name 4 factors that affect the throughput of a wireless system.
1 .AppIication requirements 2.Number of users 3.Future requirements 4.Capabilities of the products used in the design TDMM.* Page 16-3
27
What type of impact do radio communications towers have on the footprint of a facility?
They have a limited impact on the footprint (physical environment), but the towers may have a high impact on the visual environment. TDMM.* Page 16-4
28
Name 3 reasons the rooftop of a tall building may be an unsuitable location for a cellular system.
1. Difficult to get signal to street level 2. Increased potential for interference 3. Reduced frequency reuse capabilities TDMM.* Page 16-4
29
Name 3 methods for evaluating the environment in which a wireless network will be used.
1 .Site survey 2.Propagation analysis 3.ModeIing TDMM.* Page 16-4
30
Name 5 environmental factors that can affect wireless communications.
1 .Materials 2.Vegetation 3.0bjects 4.Local geography 5.Atmosphere TDMM.* Page 16-4
31
What 2 considerations does a QOS program attempt to balance?
1 .End user expectations 2.Wireless network performance TDMM.* Page 16-4
32
What term is used to describe the size or magnitude of a voltage or current waveform?
Amplitude TDMM.* Page 16-6
33
What term is used to describe the number of cycles or events per unit of time?
Frequency TDMM.* Page 16-6
34
What unit of measure is used to express the frequency of an electromagnetic signal?
Hertz (Hz) TDMM.* Page 16-6
35
What does one hertz equal?
One cycle per second TDMM.* Page 16-6
36
What term is used to describe the distance between two points of a corresponding phase of one complete cycle of a wave?
Wavelength TDMM.* Page 16-6
37
What unit of measure is typically used for wavelengths in an electromagnetic system?
Meters TDMM.* Page 16-6
38
What term is used to describe the motion of waves through or along a medium?
Propagation TDMM.* Page 16-7
39
Define line of sight in terms of propagation.
A propagation in which the radiation from the transmitter to the receiver is unobstructed TDMM.* Page 16-7
40
Name 2 types of LOS propagation.
1 .Visual 2.Radio frequency (RF) TDMM.* Page 16-7
41
What is visual LOS?
The visual observation of one point to another as seen by the observer's eye TDMM.* Page 16-7
42
What is RF LOS?
The line of sight LOS between the receiving and transmitting antennas TDMM.* Page 16-7
43
What are Fresnel zones?
A series of concentric ellipsoids surrounding the path TDMM.* Page 16-8
44
How is the first Fresnel zone used?
As a nominal unit to measure certain distances in terms of their effect on the frequency involved rather than in terms of meters (feet) TDMM.* Page 16-8
45
What is the minimum clearance requirement for reliable wireless service (expressed in Fresnel zones)?
60 percent of F1 clearance TDMM.* Page 16-8
46
Name 2 categories of barriers and obstructions that impede electromagnetic waves.
1 .Natural 2.Man-made TDMM.* Page 16-9
47
What is free space loss?
The signal attenuation that would result if all reflection, refraction, scattering, diffraction, and absorption influences were removed TDMM.* Page 16-9
48
What term refers to the abrupt change in direction of a wave at the interface between two dissimilar media such that the incident wave front returns into the medium from which it originated?
Reflection TDMM.* Page 16-9
49
What term is used to describe abrupt change in direction of a wave at the interface between two dissimilar media such that the incident wave front enters the second medium?
Refraction TDMM.* Page 16-9
50
What term describes the change in the level, direction, frequency, or polarization of incident radiation when it encounters small particles or inhomogeneous particles whose size is similar to or smaller than the wavelength of the incident radiation?
Scattering TDMM: Page 16-9
51
What term is used to describe the bending of sound, radio, or light waves around an object, barrier, or aperture edge?
Diffraction TDMM.* Page 16-9
52
What term is used to describe the loss of energy in an electromagnetic signal as it passes through a medium?
Absorption TDMM.* Page 16-9
53
What is a sky wave?
A sky wave is a wave that is usable due to reflection and refraction in the ionosphere. TDMM.* Page 16-10
54
What is the ionosphere?
The portion of the Earth's upper atmosphere where ions and electrons are present in quantities sufficient to affect the propagation of radio waves TDMM.* Page 16-10
55
Normally, the ionosphere extends ___ to ___ above the Earth.
Normally, the ionosphere extends 48 km (30 mi) to 1000 km (621 mi) above the Earth. TDMM.* Page 16-10
56
What causes the distance to the radio horizon to exceed the optical horizon within the troposphere?
Within the troposphere, bending of radio waves by refraction makes the distance to the radio horizon exceed the distance to the optical horizon. TDMM.* Page 16-10
57
At what distances does tropospheric refraction typically affect received signals?
At distances beyond the radio horizon TDMM.* Page 16-10
58
What is a direct wave?
A direct wave is an RF wave that travels directly from the transmitting antenna to the receiving antenna. TDMM.* Page 16-70
59
How can the LOS distance be extended in terrestrial communications?
By increasing the height of the transmitting antenna and/or the receiving antenna TDMM.* Page 16-10
60
What is a ground wave?
A ground wave is a wave that travels along a surface or an interface between two mediums that have different refraction indexes. TDMM.* Page 16-10
61
What is the maximum range of a surface path when high-powered transmitters and efficient antennas are used?
=500 km (310 mi) at 2 MHz TDMM.* Page 16-11
62
What is the relationship between the range of a surface path and frequency?
The surface path range decreases as frequency increases. TDMM.* Page 16-11
63
What is isotropic gain?
The ratio of actual signal strength at the antenna in a given direction relative to an ideal isotropic radiator that uniformly distributes the signal in all directions TDMM.* Pag 16-12
64
What is fading?
The variation (with time) of the amplitude or relative phase, or both, of one or more of the frequency components of a signal TDMM.* Page 16-13
65
Name the 2 types of fading.
1 .Multipath fading 2.Delay spread TDMM: Page 16-13
66
Name 4 possible outcomes of multipath.
1 .lntersymbol interference (data corruption) 2.Cancellation of signal (nulling) 3.Decrease of signal strength (downfade) 4.1ncrease of signal strength (upfade) TDMM.* Page 16-13
67
What is modulation?
The process of altering the amplitude, frequency, or phase of a carrier signal in a measured way, which allows for other signals such as voice, data, and video to be added to it TDMM.* Page 16-14
68
Name 4 types of modulation.
1 .Amplitude modulation 2.Frequency modulation 3.Phase modulation 4.PuIse modulation TDMM.* Pages 16-14 to 16-17
69
What is amplitude modulation?
The method of superimposing a signal (e.g., voice, data) on a carrier wave in which the amplitude of the carrier envelope (carrier and sidebands) is varied in relation to the signal strength TDMM.* Page 16-14
70
What is frequency modulation?
The method of superimposing a signal (e.g., voice, data, video) on an RF carrier wave in which the instantaneous frequency of the carrier wave is varied in relation to the signal strength TDMM.* Page 16-15
71
What is phase modulation?
The method of superimposing a signal (e.g., voice, data, video) on a carrier wave in which the phase of the carrier wave is varied in relation to the signal strength TDMM.* Page 16-16
72
What is pulse modulation?
The method of superimposing a series of pulses carrying the signal (e.g., voice, data, video) on a carrier wave in which the carrier wave is varied in relation to the signal strength TDMM.* Page 16-17
73
Which modulation technique uses two different phase angles that are usually out of phase by 180 degrees?
Binary phase-shift keying (BPSK) TDMM.* Page 16-18
74
Which modulation technique uses four different phase angles that are usually out of phase by 90 degrees?
Quadrature phase-shift keying (QPSK) TDMM.* Page 16-18
75
What is complementary code keying (CCK)?
A standard adopted by the IEEE 802.11 standards committee as the basis for the high-rate physical layer extension to deliver data rates of 11 Mb/s at 2.4 GHz TDMM.* Page 16-18
76
Describe how the QAM modulation technique works.
Two carriers at the same frequency are independently amplitude modulated and combined for transmission. TDMM.* Page 16-18
77
Describe how the OFDM modulation technique works.
A large number of closely spaced orthogonal sub-carriers are combined into parallel streams. TDMM.* Page 16-18
78
How does the OFDMA modulation technique achieve a more efficient use of airtime?
By scheduling the transmissions from the clients so they do not clash with each other TDMM.* Page 16-18
79
What are harmonics?
The multiples of an alternating current's fundamental frequency TDMM.* Page 16-19
80
What is the first harmonic?
The fundamental frequency TDMM.* Page 16-19
81
What is the second harmonic?
Twice the fundamental frequency TDMM.* Page 16-19
82
What is harmonic distortion?
The presence of unwanted harmonic frequencies TDMM.* Page 16-20
83
Name 4 types of harmonic filters.
1 .High-pass filter 2. Low-pass filter 3.Band-pass filter 4.Band-stop filter TDMM.* Page 16-20
84
What term describes an increase in an RF signal's power?
Gain TDMM.* Page 16-20
85
Name 2 sources of gain.
1 .External power sources 2.Passive sources TDMM.* Page 16-20
86
What term describes a decrease in signal strength?
Loss TDMM.* Page 16-20
87
Name the 2 main sources of loss in a wireless system.
1 .lmpedance of cables and connectors 2.During signal propogation that absorbs, reflects, refracts, scatters, or destroys TDMM.* Page 16-20
88
What unit provides an absolute measurement of power?
Watt TDMM.* Page 16-21
89
What unit provides a measurement of the relative gain or loss of power?
Decibel TDMM.* Page 16-27
90
What rule is commonly used to calculate isotropic gain for antennas?
The 6 dB Rule TDMM.* Page 16-21
91
Name 8 types of information that should be gathered before the wireless network is designed.
1 .Bandwidth requirement 2.Number of users 3.Growth and expandability 4.Existing data network considerations 5.User environment 6.EM and RF noise 7. Topography, terrain, and building materials 8.Climate TDMM.* Pages 16-22 to 16-24
92
Name the 2 primary types of wireless networks.
1 .Licensed 2.Unlicensed TDMM.* Page 16-25
93
What is the frequency range for P T P licensed wireless networks?
6 GHz to 40 GHz TDMM.* Page 16-25
94
What frequencies are used primarily for public safety applications?
6 GHz to 11 GHz TDMM.* Page 16-25
95
What frequencies are primarily used in the private sector for P TP applications?
18 GHz and above TDMM.* Page 16-25
96
What frequencies are the most prevalent for wireless deployments for the unlicensed spectrum?
2.4 GHz and 5 GHz TDMM.* Page 16-25
97
What frequency range is used by amateur radio operators?
2.4 GHz and below TDMM.* Page 16-25
98
How does licensing provide a higher level of interference protection than what is found in unlicensed systems?
By limiting the use of any frequency to a single user in any one area TDMM.* Page 16-26
99
What is path loss?
The loss of the RF signal power from its originating point to the ultimate end point TDMM.* Page 16-26
100
Name 5 factors that contribute to path loss.
1 .Frequency of RF signal 2. Transmission power 3.Distance between the transmit and receive antenna 4.0bstructing materials (type and density) 5. Terrain TDMM.* Page 16-26
101
Name 5 factors used to select the proper antenna for an application.
1 .Required gain 2.AIlowable wind load 3.Frequency 4.Aesthetics 5.Zoning TDMM: Page 16-27
102
What is the purpose of a radome cover for a parabolic antenna?
To keep ice and snow from accumulating on antennas and causing additional weight and wind load TDMM.* Page 16-27
103
How does a radome cover affect an RF signal?
It causes some loss as the signal passes through the cover. TDMM.* Page 16-27
104
What is the common path loss when using radome covers?
0.5 dB isotropic TDMM.* Page 16-27
105
Name 2 problems associated with oversizing antennas.
1.Interference 2.Damage to the radio equipment TDMM.* Page 16-27
106
Name the 2 basic measurements used in analyzing radio waves and other wave forms.
1 .Frequency 2.Amplitude TDMM.* Page 16-28
107
Name the 3 categories of wireless transceivers.
1 .Half-duplex 2.Frequency division duplex 3. Time division duplex TDMM.* Page 16-28
108
What type of transceiver is incapable of transmitting and receiving signals at the same time?
Half-duplex TDMM.* Page 16-28, Table 16.2
109
How does a frequency division duplex transceiver operate?
Transmits and receives simultaneously with transmitter and receiver operating on a separate pair of frequencies or duplex channel assigned in accordance with a band plan TDMM.* Page 16-28, Table 16.2
110
How does a time division duplex transceiver operate?
Transmits and receives at RF alternately in sequential time slots on a single frequency TDMM.* Page 16-28, Table 16.2
111
Define antenna.
A means for coupling RF energy from a transmitter onto the transmission medium and from the transmission medium to a receiver TDMM.* Page 16-29
112
What will happen if the wrong connector is selected and implemented in a radio system?
Selecting the wrong connector will cause degradation and failures in the radio system. TDMM.* Page 16-30
113
Name 5 considerations for implementing an outdoor P TP solution.
1 .Distance 2. Terrain 3.Climate 4.Physical obstructions 5.Cabling attenuation TDMM.* Page 16-31
114
What is a jinpole?
A rigging tool that is used to hoist sections up the tower TDMM.* Page 16-32
115
What is the benefit of using jumpers to connect the RF media to the antenna and the equipment?
Using jumpers to connect the RF media to the antenna and the equipment allows the system to be serviced without damaging any part of the system. TDMM.* Page 16-33
116
What is the weakest part of the antenna system?
The antenna connector TDMM.* Page 16-33
117
What is the purpose of a voltage injector?
To power electronic equipment located away from a convenient source of power TDMM.* Page 16-35
118
Name the 2 major types of voltage injectors.
1 .Coaxial 2.Power over Ethernet (POE) TDMM.* Pages 16-35 to 16-36
119
How far above the roof should RF media be supported?
At least 38mm (1.50 in) TDMM: Page 16-37
120
What is a distributed antenna system?
A system that transmits and receives or relays RF signals within buildings, structures, tunnels, or other areas where wireless services cannot be provided because of lack of signal penetration from outdoor networks or where no suitable outdoor network exists TDMM.* Page 16-38
121
Name 7 components of a DAS.
1. Transmitters 2.Receivers 3.Amplifiers 4. Converters 5.Cabling 6.Connectors 7.Antennas TDMM.* Page 16-38
122
Name 5 types of cable that are commonly recognized for DAS cabling distribution.
1 .Singlemode optical fiber cabling 2.Multimode optical fiber cabling 3.Hybrid optical fiber cabling 4.Balanced twisted-pair cabling 5.Coaxial cable TDMM.* Page 16-47
123
What category/class of balanced twisted-pair cabling is recommended for DAS cabling distribution?
Category 6A/Class EA TDMM.* Page 16-47
124
Excluding the base station hardware, what is the most expensive part of a DAS?
The antenna network TDMM.* Page 16-42
125
Name the 4 types of antennas used in a DAS.
1 . Omnidirectional 2. Directional 3. Radiating cable 4. Combination of all three TDMM.* Page 16-42
126
What type of antenna broadcasts equally in all directions of only one cross section of its toroidal (doughnut-shaped) three-dimensional radiation pattern?
Omnidirectional TDMM.* Page 16-42
127
What type of antenna concentrates the radiated signal in one direction more than in another or receives a signal more readily from one direction than from another?
Directional TDMM.* Page 16-43
128
Why is a radiating coaxial cabling useful in combined systems?
Because it has a wide bandwidth, allowing operation from 70 MHz to more than 2.4 GHz (with some limitations) TDMM.* Page 16-43
129
True or False A radiating cable should be placed in a metal conduit for protection.
False. A radiating cable cannot be placed in a metal conduit because it would block the radiating signal from the cable. For this reason, the cable must conform to the environmental flame spread and fire code requirements. TDMM.* Page 16-44
130
Name 5 common types of active DAS equipment.
1. Transceivers 2. Bidirectional amplifiers 3. Unidirectional amplifiers 4. Repeaters 5. Power supply units TDMM.* Page 16-47
131
What is a transceiver?
A device that uses many of its components to transmit and receive RF signals TDMM.* Page 16-47
132
What function is typically performed by the power supply unit?
The power supply unit converts the commercial ac power to dc operating voltages. TDMM.* Page 16-47
133
What is the primary headend device?
Master control unit (MCU) TDMM.* Page 16-48
134
Name 3 suitable locations for an MCU.
1 .Main equipment room (ER) 2. Telecommunications room (TR) 3.Penthouse near the roof TDMM.* Page 16-50
135
Where is DAS backend equipment typically located?
In the TR TDMM.* Page 16-51
136
Name 6 examples of DAS backend equipment.
1. Slave processors 2. Power supplies 3. Host ports 4. Amplifiers and transceivers 5. Antenna ports 6. Antennas TDMM.* Page 76-51
137
Name the 3 primary means used by active DAS to transport radio signals.
1. Analog modulation of RF signals onto an optical carrier 2. Down conversion of RF signals to IF 3. Digital sampling of RF signals TDMM.* Page 16-52
138
What is an advantage of analog modulation?
The ability to modulate a large portion of the radio spectrum over one optical path TDMM.* Page 16-52
139
What is a major problem associated with analog systems?
The direct dependency of the modulation and recovery of the RF signal to the optical transport TDMM: Page 16-52
140
What is the primary medium used for DAS analog systems?
Singlemode optical fiber TDMM.* Page 16-52
141
How do DAS analog systems compensate for the dependency on optical losses?
By using an automatic gain control (AGC) as a feedback loop to maintain constant optical strength over the optical fiber plant TDMM: Page 16-52
142
How is passive distribution equipment in a DAS defined?
As equipment that does not require external power input TDMM.* Page 16-54
143
What is a directional coupler?
A linear device that uses induction or another method to differentially split downlink power from an input connector to two or more output connectors TDMM.* Page 16-54
144
What piece of passive DAS equipment combines dc power with the ac RF signal on a coaxial cable and taps it off at the other end?
Bias tee TDMM.* Page 16-54
145
What piece of passive DAS equipment is used to combine two wireless bands to a single antenna feed or distribution cable?
Hybrid coupler TDMM.* Page 16-54
146
Which piece of passive DAS equipment accepts an input signal and delivers multiple output signals with specific phase and amplitude characteristics?
Power splitter TDMM.* Page 16-54
147
Name 3 characteristics of output signals in power splitters.
1. Equal amplitude 2. Zero degree phase relationship between any two output signals 3. High isolation between each output signal TDMM.* Page 16-54
148
Name 2 common topologies that serve a DAS within a building structure.
1 .Star topology 2. Tapped trunk topology TDMM: Page 16-54
149
Name 3 factors that may affect the selection of a cabling topology for a DAS.
1 .DAS equipment 2.CabIing medium used in a new installation 3.Legacy cabling system in a previous installation TDMM.* Page 16-54
150
What cabling mediums may be used in the installation of a star topology?
*Balanced-twisted pair *Coaxial *Optical fiber *Combination TDMM.* Page 16-55
151
What types of cabling may be used to install a tapped trunk topology?
*Coaxial *Optical fiber TDMM.* Page 16-55
152
What component is used to "tap" into the coaxial cable of a tapped trunk topology?
Splitter or vampire tap TDMM.* Page 16-55
153
Name 2 potential problems associated with using a DAS to support mobile communications in buildings.
1 .Availability and usability of RF signals in the intended coverage areas (coverage) 2.Ability to support the demands of the system users and recipients (capacity) TDMM.* Page 16-55
154
Name the 3 phases associated with DAS design.
1.Pre-lnstallation 2.Installation 3.Acceptance/implementation TDMM.* Page 16-55
155
What is the purpose of conducting RF measurements during an on-site survey of the radio environment?
To identify existing signals and their frequency and strength TDMM.* Page 16-56
156
Name 2 factors that determine the overall usability and capability of an installed DAS.
1 .Antenna Selection 2.Antenna Location TDMM.* Page 16-58
157
What is the link budget (operating margin)?
The sum of ICT gains and losses in an ITS, beginning with the transmitter and continuing to the receiver, including transmission line loss and antenna gains TDMM.* Page 16-59
158
Name 3 objectives of diplexing.
1 .Maintain proper transmission limits set by the manufacturer or regulatory body 2.Provide adequate bandwidth at each frequency that is diplexed 3.Control and minimize signal loss TDMM.* Page 16-60
159
What is duplexing?
Combining the forward and reverse signal paths into a single cable TDMM.* Page 16-60
160
Name 6 applications where battery backup for the DAS is typically required.
1 .Private security services 2.Hospitals and health care facilities 3.Mining and mine operations 4.Government and military installations 5.Financial markets 6.Life safety issues TDMM.* Page 16-62
161
Name 6 strategies for mitigating interference between a DAS and other RF frequencies that are in use in the area.
1.Relocate transmission devices 2.Adjust or reassign transmission frequency 3.Replace receiving antennas 4.Discontinue the use of an interfering frequency 5.Install RF filters or chokes 6.Install RF shielding material TDMM: Page 16-62
162
What is a personal area network (PAN)?
The interconnection of information technology devices within a personal operating space TDMM.* Page 16-65
163
What is the typical radius of a PAN?
-10 m (33 ft) TDMM.* Page 16-65
164
Name 3 key factors for a PAN.
1. Lower power consumption 2. Low cost 3. Superior ease of use TDMM.* Page 16-65
165
What is the intent of the IEEE 802.15 Working Group?
To enhance the Bluetooth specification and create a standard TDMM.* Page 16-65
166
Which organization administers the IR standard?
Infrared Data Association (IrDA) TDMM.* Page 16-66
167
True or False IR is unaffected by RF.
True. IR is unaffected by RF, but it can be affected by ambient light. TDMM.* Page 16-66
168
True or False The IrDA standard does not have any provisions for security.
True. The IrDA standard does not have any provisions for security. Security is left to the software and firmware applications utilizing IR transmission. TDMM.* Page 16-66
169
What is the intended purpose of a public WLAN or hotspot?
To provide convenient access to Internet-based telecommunications and information to users equipped with WLAN-capable devices TDMM.* Page 16-67
170
Name the 3 categories of WLAN services based on access restrictions.
1. Unrestricted access 2. Established account access 3. Temporary account access TDMM.* Page 16-67
171
Which IEEE Working Group is responsible for WLAN specifications?
IEEE 802.11 Working Group TDMM.* Page 16-68
172
Name the 3 types of logical configurations for WLANs as defined in IEEE standards.
1. Independent basic service set (IBSS) 2. Basic service set (BSS) 3. Extended service set (ESS) TDMM.* Page 16-69
173
When is an IBSS WLAN enabled?
When two or more stations equipped with wireless NICs communicate with each other TDMM.* Page 16-69
174
When is a BSS WLAN enabled?
When a single AP is used to manage the communications between two or more stations equipped with wireless NICs TDMM.* Page 16-69
175
When is an ESS WLAN enabled?
When two or more BSS APs are linked TDMM.* Page 16-69
176
Which WLAN configuration transfers messages directly between devices without the need for an AP?
IBSS TDMM.* Page 16-69
177
What term is used to describe the requirement to obtain and install an AP before enabling wireless communications for a BSS WLAN?
Infrastructure mode TDMM: Page 16-69
178
How are APs described when cabling is used to create a distribution system for an ESS WLAN?
As portals or gateways TDMM.* Page 16-69
179
What is the role of the NIC?
To enable a stand-alone device to function as a station on a WLAN (client) TDMM.* Page 16-72
180
Which station software component makes it possible for the OS to configure and use the NIC for all WLAN communications?
The driver TDMM.* Page 16-72
181
What is the role of an access point (AP)?
To serve as a central point for communications and management on a WLAN TDMM.* Page 16-72
182
What is the initial destination of all messages sent by a station in a WLAN?
The access point (AP) TDMM.* Page 16-72
183
How are bridges used in both cabled and wireless network environments?
To link access devices and extend the physical span or coverage zone of a network TDMM.* Page 16-74
184
What is the role of a repeating bridge?
To transfer all signals received from each endpoint to the other endpoint TDMM.* Page 16-75
185
What type of network device is designed to centrally manage all connected APs in a WLAN?
WLAN switch or controller TDMM.* Page 16-76
186
Which WLAN component is used to connect multiple networks and allow devices to communicate between networks?
Gateways TDMM.* Page 16-77