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Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
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OCR for page 182
Page 182
C
Glossary
ACE (advanced communications
engine) is a prototype multiband, multimode software radio capable
of emulating both military combat net radios and commercial
avionics radio systems.
ACN (airborne communications node)
is an unmanned aerial vehicle designed and equipped to provide
hierarchical communications services and crosslinking over a broad
theater of operations. See RAP and UAV.
ACTS (Advanced Communications
Technologies and Services program) is the European Commission's
latest precompetitive research effort focusing on advanced
communications systems.
A/D converter is an
analog-to-digital converter.
AJ (antijam) refers to techniques
for reducing the effectiveness of attempts to jam communications
channels. See Jamming.
AMPS (advanced mobile phone system)
is the standard for the analog cellular radio telephones now widely
available throughout the United States.
ARQ (automatic repeat request) is a
protocol used to retransmit data packets received in error.
ASIC is an application-specific
integrated circuit.
ATM (asynchronous transfer mode)
enables voice, data, and video to be handled with a uniform
transmission protocol. It breaks up the information to be
transmitted into short packets of data and intersperses them using
time division with data from other sources and delivered over trunk
networks.
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Representative terms from entire chapter:
satellite communications
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ATM cell is an information packet
containing 53 bytes of data traffic and additional ''overhead"
defining the virtual circuits and paths over which the data are to
be transmitted.
Bandwidth is the part of a
frequency band occupied by a communications channel. Sometimes the
term is used to describe the number of bits per second transmitted
in a channel.
Bent pipe is a satellite
communications system that transmits to an Earth station
essentially the same signal it receives from another Earth
station.
BER (bit-error rate) is the
probability that a bit is received in error.
Bit is a binary unit of
information.
bps (bits per second) refers to the
speed at which data is generated by a source or transmitted over a
communications channel. Measurements are often stated in units of
103 bits per second (kilobits or
kbps) or 106 bits per second
(megabits or Mbps).
Byte is a unit of 8 bits.
C4I (command, control, communications,
computing, intelligence) is a military concept encompassing all the
functions and capabilities sought in an advanced communications
system.
CDMA (code division multiple
access) is a technique that allows many users to share the same
radio spectrum. A sequence of pseudo-random bits, known as a code,
spreads the information signal over a much larger range of
frequencies than is occupied by the original information signal.
See FDMA, TDMA, spread spectrum.
CDPD (cellular digital packet data)
is a packet-switched network that uses one or more channels in an
analog cellular telephone system.
Cell refers to a geographic region
within which cellular telephone subscribers can communicate with a
particular base station (site). Cell radius ranges from 0.5-15
kilometers depending on the density of the subscribers and the
extent of topological obstructions.
CELP (code excited linear
prediction) is a technique for encoding voice.
CMOS (complementary metal oxide
semiconductor) is an inexpensive, low-power integrated circuit
technology.
CONDOR is a National Security
Agency program designed to develop and demonstrate secure voice and
secure net broadcast services, using STU III-compatible units, over
the commercial cellular infrastructure.
COTS (commercial off-the-shelf)
refers to readily available commercial technologies and
systems.
CSMA/CD (carrier-sense multiple
access with collision detection) is a
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protocol that regulates the manner in
which terminals gain access to a shared communications channel.
DAMA (demand-assigned multiple
access) is a technique that enables many users to share the same
radio spectrum. A common signaling channel is assigned to handle
requests from transmitters for network capacity.
dB is decibels, a unit for
expressing the relative intensity of acoustic and electromagnetic
waves.
DBS (direct broadcast satellite) is
a system in which GEO satellites broadcast a signal with sufficient
power to enable direct reception in a home, office, or vehicle with
an inexpensive receiver.
DFE (decision feedback equalizer)
is a nonlinear equalization technique designed to reduce the
effects of intersymbol interference. See ISI.
Doppler effect is a change in the
received signal frequency due to movement of the transmitter or
receiver.
DSP (digital signal
processor/processing) is a specialized integrated circuit used to
analyze or alter the characteristics of communications signals.
Erlang is a unit reflecting the
traffic intensity on a communication link. It is equivalent to the
fraction of time that the link is occupied.
ETSI is the European
Telecommunications Standards Institute.
Fading refers to changes in the
amplitude of received signals due to characteristics of the
transmission path and motion of the transmitter and receiver.
FCC is the Federal Communications
Commission.
FDMA (frequency division multiple
access) is a technique that enables many users to share the same
radio spectrum. Each user is allocated a different frequency. This
is the approach used in AMPS cellular radio. See CDMA, TDMA.
FEC (forward error correction)
codes give digital signals a highly specialized redundancy that
enables a receiver to recognize and correct occasional errors in
the received signal.
FH (frequency hopping) is a
technique for changing transmit frequency in a way that makes it
difficult for an adversary to jam communications.
FIR (finite impulse response)
refers to a signal-processing operation performed by a DSP.
FM (frequency modulation) is a
modulation technique in which information is conveyed in the high
frequency of a carrier signal.
FPLMTS (future public land mobile
telecommunication system) is the original name for the
International Telecommunications Union's concept
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for third-generation wireless telephone
systems. It is now called IMT-2000.
Frequency reuse refers to the use
of the same signal spectrum at different geographical
locations.
GBS (global broadcast system) is an
advanced military satellite communications system designed to have
very high data rates (100 megabits per second) and global
coverage.
GEO (geosynchronous orbit) refers
to an equatorial satellite orbit approximately 36,000 kilometers
from the Earth in which the satellite remains stationary over one
position on the Earth's surface.
GloMo (Global Mobile Information
Systems) is a research and demonstration program dealing with
mobile, wireless communications. It is funded by the Defense
Advanced Research Projects Agency.
GSM (global system for mobile
communications) is a combination TDMA/FDMA cellular radio system
that is the current digital standard in Europe. It was originally
known as group system mobile.
Have Quick is a military UHF radio
designed to provide secure air-to-air and air-to-ground
communications with AJ capabilities.
HF (high frequency) is the
frequency band at 3–30 megahertz.
HIPERLAN is a high-performance
radio local-area network designed to operate at 20 megabits per
second.
Hz (hertz) refers to a unit of
frequency equal to one cycle per second. Frequencies are often
stated in units of 103 hertz
(kilohertz or kHz), 106 hertz
(megahertz or MHz), or 109 hertz
(gigahertz or GHz).
IC is an integrated circuit.
IEEE is the Institute of Electrical
and Electronics Engineers.
IMT-2000 (International Mobile
Telecommunications-2000) is the International Telecommunications
Union's concept for third-generation mobile wireless telephone
systems.
Information warfare refers
primarily to recent U.S. initiatives designed to protect computer
network infrastructures against intentional disruptions. The term
encompasses many forms of disruption aimed at communications
networks (both wired and wireless) and the relevant
countermeasures.
INMARSAT (International Maritime
Satellite) is an organization of 75 member countries that has
launched several generations of satellite communications systems
for voice and low-rate data applications.
Intelsat is an international,
government-chartered organization established in 1964 to coordinate
worldwide satellite communications programs.
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A series of INTELSAT communications
satellites has been launched.
IS-95 is the North American
standard for second-generation CDMA digital wireless telephone
systems.
IS-136 is the North American
standard for second-generation TDMA digital wireless telephone
systems.
ISDN (integrated services digital
network) is a set of international standards that specify the
manner in which different types of information (e.g., voice, data,
video) can be transmitted in the same communications system.
ISI (intersymbol interference)
occurs when multipath reflections corresponding to a given bit
transmission arrive at the receiver simultaneously with subsequent
data bits.
ISM (industrial, scientific, and
medical) refers to the unlicensed frequency bands available for use
by any wireless device that conforms to rules established by the
FCC.
ITU is the International
Telecommunications Union.
Jamming is a type of transmission
designed to disrupt the radio communications of an adversary so as
to interfere with military operations.
JCIT (Joint C4I Terminal) is a software-defined radio
under development by the Naval Research Laboratory that will
implement combat net, intelligence communications, and military
datalinks on a single platform.
LAN is a local area network.
LEO (low Earth orbit) is a
satellite communications system deployed in a low orbit (500 to
2,000 kilometers from Earth).
LOS (line of sight) refers to a
radio communications systems with an unobstructed path between the
transmitter and receiver.
LPC (linear predictive coding) is a
coding technique based on a mathematical model of a voice
signal.
LPD/I (low probability of detection
and interception) refers to the capability to minimize an
adversary's awareness of transmitted radio energy, ability to
measure any properties of a detected signal, or ability to
intercept the transmission.
MEO (medium Earth orbit) is a
satellite orbit of intermediate height between LEO and GEO
orbits.
Message store-forward is a system
in which a message is uploaded to a satellite and held there until
the satellite is in a position to download it to the destination.
It is an alternative to bent-pipe systems.
Millennium is a military research
effort to design an ultra-wideband
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radio. One objective is to demonstrate
extremely high-speed A/D converters for military and commercial
applications.
MISSI (Multilevel Information
Systems Security Initiative) is a National Security Agency
initiative designed to provide a framework for the development of
interoperable, complementary security products.
MMITS (Modular Multifunction
Information Transfer System) is an industry forum focusing on
technical standards and applications for software-defined radios,
networking radios, and multimode radios.
Mobile IP (mobile internetworking
routing protocol) is designed to support mobile Internet users.
MSE (mobile subscriber equipment)
is a military radio that resembles a cellular telephone.
MSRT (mobile subscriber radio
terminal) is a military radio.
Multipath propagation is a
phenomenon in which copies of a transmitted signal arrive at
different times at a receiver.
NATO is the North Atlantic Treaty
Organization.
NES (network encryption system) is
an encryption system certified by the National Security Agency that
enables clusters of defense computer networks to interconnect
through the unclassified Internet.
OSI (Open Systems Interconnection)
refers to a model that describes networks as a series of
layers.
Packet is a collection of
information symbols transmitted together on a communications
channel.
PACS (personal access
communications system) is a U.S. standard for second-generation
digital wireless telephone systems serving subscribers moving at
pedestrian speeds.
PDA (personal digital assistant) is
a portable, low-power computing device with a small display used
for information storage.
Peer-to-peer is a network
architecture in which transmissions flow between terminals without
passing through a central hub.
Personal communications services
are offered in frequency bands around 1900 megahertz allocated for
this purpose by the FCC.
PHS (personal handyphone system) is
a Japanese standard for mobile digital telephone services.
PSTN (public switched telephone
network) is a collection of worldwide wired telephone networks.
QoS (quality of service) refers to
end-to-end performance guarantees offered by a network.
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RACE (Research for Advanced
Communications in Europe) was a program funded by the European
Commission to perform precompetitive research on advanced
communications systems. It was superseded by the ACTS program.
Radio spectrum is a range of radio
frequencies required to support one or more communications
channels.
RAM is random-access memory.
RAP (radio access point) is a
wheeled or tracked vehicle that carries extensive communication
systems, including an "on the move" antenna system. It provides a
variety of cross-networking, repeater, and information
services.
RF is radio frequency.
RMS (root mean square) is the
standard deviation of a random variable.
RSVP (resource reservation
protocol) supports the delivery of real-time information over the
Internet.
RTP (real-time protocol) is
designed to support delay-intolerant data streams, such as video,
transmitted over the Internet.
S3 (Scalable Self-Organizing
Simulations) is a research program that uses parallel computers to
simulate communications networks. The program is sponsored by the
Defense Advanced Research Projects Agency and the National Science
Foundation.
SHF (superhigh frequency) is the
frequency band at 3-30 gigahertz used for satellite, radar, and
microwave communications.
SINCGARS (single-channel ground and
airborne radio system) is a military radio that hops transmission
frequencies within the very-high-frequency band, a capability that
helps prevent jamming.
SNR (signal-to-noise ratio) is the
ratio of signal power to noise power. The higher the SNR, the
clearer the transmission.
Software-defined radio is a radio
implemented on DSPs with functions defined by software, which can
be downloaded as needed. Such radios can use many types of
modulations.
SpeakEASY is a software-defined
radio designed and demonstrated with support from the Defense
Advanced Research Projects Agency. SpeakEASY can emulate some
legacy military radio systems and operate across a wide frequency
range.
Spectral link efficiency is the
data rate (in bits per second) per unit of bandwidth of a
communications channel.
Spread spectrum is a technique in
which a signal is spread over a much larger frequency range than
the minimum required to deliver the message. It is often used by
the military for antijam purposes. It is used by the commercial
sector in CDMA mobile telephone systems and wireless LANs.
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STU III (Secure Terminal Unit III)
is a standardized voice and data telephone capable of encryption up
to top-secret level for defense and civilian government purposes.
STU III operates over standard dial-up telephone lines and has been
extended to cellular applications.
Symbol, as used in this report,
refers to a series of encoded bits.
TDMA (time division multiple
access) is a technique that allows many users to share the same
radio spectrum by transmitting information in different time slots.
See CDMA, FDMA.
Throughput, as used in this report,
refers to the fraction of time during which a communications
channel can be used.
UAV (unmanned aerial vehicle) is an
unmanned aircraft used to relay radio signals between two points on
the ground.
UHF (ultrahigh frequency) is the
frequency band at 0.3–3 gigahertz used for UHF television and
radar systems.
UMTS (universal mobile telephone
system) is a pending European standard for mobile communications
services, scheduled to be deployed beginning in 2002.
USAT an ultrasmall-aperture
terminal.
VHF is the frequency band at
30–300 megahertz used for FM radio and television.
VSAT (very small aperture terminal)
is a satellite communications system in which Earth stations do not
require large antennas. The small antenna size (typically less than
1 meter) allows for simplified installation and possibly
portability.
WAN is a wide area network.
Winforum (Wireless Information
Network Forum) was formed by several companies in 1992 to obtain
frequency bands and set protocol standards for personal
communications data services.
WLAN is a wireless local area
network.
