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GLOSSARY OF TERMS AND ABBREVIATIONS 

Terms 

Attenuation - The decrease in intensity of a signal, beam, or wave as a result of absorption of 

energy and of scattering out of the path to the detector, but not including the reduction due to 

geometric spreading. 

Diffraction - The deviation of an electromagnetic wavefront from the path predicted by 

geometric optics when the wavefront interacts with, i.e., is restricted by, a physical object 

such as an opening (aperture) or an edge. 

Duplex – A communications mode with the ability to transmit and receive radio traffic 

simultaneously through two different frequencies, one to transmit and one to receive.

Multipath – The propagation phenomena that results in radio signals’ reaching the antenna by 

two or more paths. Causes of multipath include atmospheric ducting, ionospheric reflection 

and refraction, and refraction from terrestrial objects such as mountains or buildings. 

Permittivity - A measure of the ability of a material to resist the formation of an electric field 

within it. Also called dielectric constant, relative permittivity. 

Project MESA – Project MESA is an international partnership producing globally applicable 

technical specifications for digital mobile broadband technology, aimed initially at the sectors 

of public safety and disaster response.

Rake Technique - A receiver technique that uses several baseband correlators to individually 

process several signal multipath components. The correlator outputs are combined to achieve 

improved communications reliability and performance. 

Reflection - The abrupt change in direction of a wavefront at an interface between two 

dissimilar media so that the wavefront returns into the medium from which it originated. 

Refraction - Retardation, and—in the general case—redirection, of a wavefront passing 

through (a) a boundary between two dissimilar media or (b) a medium having a refractive 

index that is a continuous function of position, e.g., a graded-index optical fiber. 

Repeater - An analog device that amplifies an input signal regardless of its nature, i.e., analog 

or digital. A digital device that amplifies, reshapes, retimes, or performs a combination of any 

of these functions on a digital input signal for retransmission. 

Scattering - Of a wave propagating in a material medium, a phenomenon in which the 

direction, frequency, or polarization of the wave is changed when the wave encounters 

discontinuities in the medium, or interacts with the material at the atomic or molecular level. 

Simplex – A communications mode with the ability to transmit or receive in one direction at a 

time. Simultaneous transmission cannot occur. 

Trunking – In radio in communications, it is a system that may include a single user of 

different workgroups, which uses a group of radio frequencies (a trunk). The system is 

dynamically controlled by a computer, which directs a transmission to an available channel 

or frequency. 
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Wavefront - The surface defined by the locus of points that have the same phase, i.e., have 

the same path length from the source. 1. The wavefront is perpendicular to the ray that 

represents an electromagnetic wave. 2. The plane in which the electric and magnetic field 

vectors lie is tangential to the wavefront at every point. 3. The vector that represents the 

wavefront indicates the direction of propagation. 

Abbreviations and Acronyms 

3G third generation 

ac alternating current 

AGC automatic gain control 

AM amplitude modulation 

AMPS advanced mobile phone system (cellular system) 

AOA angle of arrival 

ARRL American Radio Relay League 

ATM asynchronous transfer mode 

AWGN additive white Gaussian noise 

BDA bi-directional amplifier 

BFRL Building and Fire Research Laboratory 

BPL broadband power line 

bps bits per second 

CDMA code division multiple access 

CFP contention-free period 

cm centimeter 

COW Cellular on Wheels 

CP contention period 

CSMA carrier sense multiple access 

DARPA Defense Advanced Research Projects Agency 

dB decibel 

dc direct current 

DCF distributed coordination function 

DES Data Encryption Standard 

DSL digital subscriber line 

DSP digital signal processor 

DTIC Defense Technical Information Center 

EDCF enhanced distributed coordination function 

EHF extremely high frequency 

ELF extremely low frequency 

EMS emergency medical service 

ETSI European Telecommunications Standards Institute 

FCC Federal Communications Commission 

FDNY Fire Department of New York 

FEC forward error correction 

FEMA Federal Emergency Management Agency 
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FM frequency modulation 

FSK frequency shift keying 

GHz gigahertz 

GIS Geographic Information System 

GPS Global Positioning System 

GSM global system for mobile communication (cellular phone technology) 

HC hybrid coordinator 

HCF hybrid coordination function 

HDTV high-definition television 

HF high frequency 

HVAC heating, ventilation, and air conditioning 

Hz hertz 

IAL Intel Architecture Laboratories 

ICP incident command post 

IETF Internet Engineering Task Force 

IF intermediate frequency 

IP Internet protocol 

ISL Information Systems Laboratory 

ISM industrial, scientific, medical 

kHz kilohertz 

km kilometer 

LAN local area network 

LCD liquid crystal display 

LF low frequency 

LOS line of sight 

LV low voltage 

M mega 

m meter; milli 

MAC medium access control 

MANet mobile area network 

MEA mesh-enabled architecture 

MHz megahertz 

MIMO multiple input, multiple output 

MRS Mine Radio Systems Inc. 

MSSI Multi Spectral Solutions, Inc. 

MV medium voltage 

mW milliwatt 

NFPA National Fire Protection Association 

NIOSH National Institute for Occupational Safety and Health 

NIST National Institute of Standards and Technology 

NLM National Library of Medicine 

NLOS non-line of sight 

NOI notice of inquiry 

NPRM notice of proposed rule making 
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NTIA National Telecommunications and Information Administration 

OFDM orthogonal frequency division multiplexing 

OOK on/off keying 

PAM pulse amplitude modulated 

PAN personal area network 

PAS personal accountability system 

PASS Personal Alarm Safety System 

PCF point coordination function 

PCS personal communications system 

PED personal emergency device 

PLC power line communication 

PLL phase-lock loop 

PN pseudo noise 

PPE personal protective gear 

PPM pulse position modulation 

PRF pulse repetition frequency 

PSWAC Public Safety Wireless Advisory Committee 

QDMA quadrature division multiple access 

QoS quality of service 

RF radio frequency 

SBIR small business innovation research 

SCBA self-contained breathing apparatus 

SDTV standard-definition television 

SHF super high frequency 

SNR signal-to-noise ratio 

TDMA time division multiple access 

TDOA time difference of arrival 

TTCP The Technical Cooperation Program] 

TTE through-the-earth 

UHF ultra high frequency 

USFA U.S. Fire Administration 

UWB ultra wideband 

VCO voltage-controlled oscillator 

VHF very high frequency 

VLF very low frequency 

WAP Wireless Application Protocol 

WLAN wireless local area network 

WPAN wireless personal area network 

WPI Worcester Polytechnic Institute