2.5G
Describes the state of wireless technology and capability usually associated with General Packet Radio Services (GPRS), that
is, between the second and third generations of wireless technology. Each generation provides a higher data rate and
additional capabilities. The term "2.5G" is generally thought to portray the present state of the technology. WIS
3G
A term for third-generation wireless, referring to near-future developments in personal and business wireless technology,
especially mobile communications. This phase is expected to reach maturity between the years 2003 and 2005. Among its expected
features are enhanced multimedia; support for use in all popular modes (cellular telephone, e-mail, paging, fax,
videoconferencing, Web browsing); broad bandwidth and high speed (upwards of 2 Mbps); routing flexibility (repeater,
satellite, LAN); operation at approximately 2 GHz transmit and receive frequencies; and roaming capability throughout Europe,
Japan, and North America.
WPD
802.1x
The new standard for wireless LAN security, as defined by the Institute of Electrical and Electronics Engineers (IEEE). An
access point that supports 802.1X and its protocol, Extensible Authentication Protocol (EAP), acts as the interface between a
wireless client and an authentication server, such as a Remote Authentication Dial-In User Service (RADIUS) server, to which
the access point communicates over the wired network.
CIS
Air Interface
In cellular telephone communications, the radio frequency portion of the circuit between the cellular phone set or wireless
modem (usually portable or mobile) and the active base station. As a subscriber moves from one cell to another in the system,
the active base station changes periodically. Each changeover is known as a handoff. WIS
Aloha
A protocol for satellite and terrestrial radio transmissions. In pure Aloha, a user can transmit at any time but risks
collisions with other users' messages. "Slotted Aloha" reduces the chance of collisions by dividing the channel into time
slots and requiring that the user send only at the beginning of a time slot. Aloha was the basis for Ethernet, a local area
network protocol. WPD
Amateur Radio
Also known as "ham radio," communication in a range of frequencies designated for amateur use by the FCC from just above the
AM broadcast band (1.6 MHz) to the microwave region, at several hundred gigahertz. Anyone with a radio receiver or a radio
scanner can listen in on ham radio communications, but only an operator licensed by the FCC can transmit the signals. WPD
ATM
Asynchronous Transfer Mode: A transfer mode in which the information is organized into cells; it is asynchronous in the sense
that the recurrence of cells containing information from an individual user is not necessarily periodic. ATM is specified in
international standards such as ATM Forum UNI 3.1. IBM
B8ZS
Bipolar 8-Zero Substitution, also called Binary 8-Zero Substitution, Clear Channel, and Clear 64: An encoding method used on
T1 circuits that inserts two successive ones of the same voltage-referred to as a bipolar violation-into a signal whenever
eight consecutive zeros are transmitted. The device receiving the signal interprets the bipolar violation as a timing mark,
which keeps the transmitting and receiving devices synchronized. Ordinarily, when successive ones are transmitted, one has a
positive voltage and the other has a negative voltage. WIS
Bit Error Rate
In a digital transmission, the percentage of bits with errors divided by the total number of bits transmitted, received, or
processed over a given time period. The rate is typically expressed as 10 to the negative power. Bit Error Rate (BER) is the
digital equivalent to signal-to-noise ratio in an analog system. WPD
Bit Robbing
A technique used in the T-carrier system. In the basic T1 system, a 193-bit frame, serving 24 channels, is transmitted in a
sequence of 12 frames referred to as a "superframe." Special signaling information, such as whether a voice channel is on-hook
or off-hook, is included within the superframe using a bit (called the "A bit") "robbed" from the sixth frame as a signaling
bit, and another bit (the "B bit") robbed from the 12th frame. WIS
Bit Stuffing
In telecommunications, the addition of a small number of binary digits to a transmission unit in order to fill it to a
standard size or to help synchronize signaling rates between points in a network. The receiver knows how to detect and remove
or disregard the stuffed bits.
WIS
Bluetooth
Refers to a short-range radio technology aimed at simplifying communications among Internet devices and between devices and
the Internet, and also at simplifying data synchronization between Internet devices and other computers. WPD
Bps
Bits per second
Broadcast
Transmission of the same data to all destinations.
IBM
CDMA
Code-Division Multiple Access: Any of several protocols used in so-called "second-generation" (2G) and "third-generation" (3G)
wireless communications. As the term implies, CDMA is a form of multiplexing, allowing multiple signals to occupy a single
transmission channel, optimizing the use of available bandwidth. The technology is used in ultra-high-frequency (UHF) cellular
telephone systems in the 800-MHz and 1.9-GHz bands. WIS
Cell of Origin
COO, a mobile positioning technique for finding a caller's cell (the basic geographical coverage unit of a cellular telephone
system) location. It may be used by emergency services or commercial use. COO is the only positioning technique that is widely
used in wireless networks and is used for Phase 1 of 911 service in the United States.
WIS
Cellular Telephone
Telephone systems, especially the Advance Mobile Phone Service (AMPS), that divide a geographic region into sections called
cells. The purpose of this division is to make the best use of a limited number of transmission frequencies. Each connection,
or conversation, requires its own dedicated frequency, and the total number of available frequencies is about 1,000. To
support more than 1,000 simultaneous conversations, cellular systems allocate a set number of frequencies for each cell. Two
cells can use the same frequency for different conversations so long as the cells are not adjacent to each other. WPD
Channel Bank
The foundation of all digital telecommunication transmissions, the part of a carrier-multiplex terminal that multiplexes a
group of channels into a higher bit-rate digital channel, and demultiplexes these aggregates back into individual channels. A
channel bank changes analog voice and data signals into a digital format. It is called a "bank" because it can contain enough
processing power to convert a bank of up to 24 individual channels to a digital format, then back to analog again. The 24
channels constitute a T1 circuit. WPD
Cloud
Also referred to as a "network cloud," in telecommunications, a public or semi-public space on transmission lines (such as T1
or T3) that exists between the end points of a transmission. Data transmitted across a WAN enters the network from one end
point using a standard protocol suite such as Frame Relay, then enters the network cloud where it shares space with other data
transmissions. The data emerges from the cloud in the same format in which it entered the cloud. A network cloud exists
because when data is transmitted across a packet-switched network in a packet, no two packets will necessarily follow the same
physical path. The unpredictable area that the data enters before it is received is the cloud.
WPD
CO
Central Office: In telephony, a telecommunications office centralized in a specific locality to handle the telephone service
for that locality. Telephone lines are connected to the CO on a local loop. The CO switches calls between local service and
long-distance service. ISDN and DSL signals also channel through the CO. WPD
COFDM
Coded Orthogonal Frequency Division Multiplexing: A modulation scheme that divides a single digital signal across 1,000 or
more signal carriers simultaneously. The signals are sent at right angles to each other (hence, orthogonal) so they do not
interfere with each other. COFDM is used predominately in Europe and is supported by the Digital Video Broadcasting (DVB) set
of standards. In the U.S., the Advanced Television Standards Committee (ATSC) has chosen 8-VSB (8-level Vestigial Sideband) as
its equivalent modulation standard. WIS
Colocation
A server, usually a Web server, located at a dedicated facility designed with resources which include a secured cage or
cabinet, regulated power, dedicated Internet connection, security and support. These facilities offer the customer a secure
place to physically house their hardware and equipment where the potential for fire, theft, or vandalism is limited.
WPD
Computer-Telephony Integration
Refers to systems that enable a computer to act as a call center, accepting incoming calls and routing them to the appropriate
device or person. These systems can handle a variety of incoming and outgoing communications, including phone calls, faxes,
and Internet messages.
WPD
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Dedicated Line
Also known as a nonswitched line, a telecommunication path between two points available 24 hours a day for use by a designated
user (individual or company), rather than shared among multiple users as dial-up lines are. A dedicated line can be a physical
path owned by the user or rented from a telephone company, in which case it is called a leased line.
WIS
Direct Sequence Spread Spectrum
DSSS, one of two types of spread spectrum radio, the other being frequency-hopping spread spectrum. DSSS is a transmission
technology used in Local Area Wireless Network (LAWN) transmissions where a data signal at the sending station is combined
with a higher data rate bit sequence, or chipping code, that divides the user data according to a spreading ratio. The
chipping code is a redundant bit pattern for each bit that is transmitted, which increases the signal's resistance to
interference. If one or more bits in the pattern are damaged during transmission, the original data can be recovered due to
the redundancy of the transmission.
WPD
DS Levels
A term for the series of standard digital transmission rates or levels based on DS0, a transmission rate of 64 Kbps, the
bandwidth normally used for one telephone voice channel. Both the North American T-carrier system and the European E-carrier
systems of transmission operate using the DS series as a base multiple. The digital signal is what is carried inside the
carrier system.
- DS0 is the base for the digital signal X series.
- DS1, used as the signal in the T-1 carrier, is 24 DS0 (64 Kbps) signals transmitted using pulse-code modulation (PCM)
and time-division multiplexing (TDM).
- DS2 is four DS1 signals multiplexed together to produce a rate of
6.312 Mbps.
- DS3, the signal in the T-3 carrier, carries a multiple of 28 DS1
signals or 672 DS0s or 44.736 Mbps.
WIS
Enhanced Specialized Mobile Radio
A wireless communication system in which numerous mobile or portable transceivers are linked in a network of repeaters. Each
repeater has a range of approximately 5 to 10 miles. Operating frequencies are in the UHF (ultra-high-frequency) range, that
is, between approximately 300 MHz and 3 GHz. Usually, the working band is near 900 MHz.
WIS
Erlang
A unit of traffic density in a telecommunication system. One erlang is the equivalent of one call (including call attempts and
holding time) in a specific channel for 3,600 seconds in an hour. The 3,600 seconds need not be, and generally are not, in a
contiguous block.
WIS
Ethernet Point of Presence
A technology developed by Level 3 Communications that provides widespread access to broadband networks. As a large network
increases its bandwidth, it can include large and expanding groups of subscribers. This trend, largely the result of the
deployment of fiber-optic infrastructure, is expected to continue. Thus, wide-area networks (WANs) are taking on some of the
characteristics previously unique to local area networks (LANs). The opposite is also true: LANs are becoming increasingly
complex, resembling WANs in miniature. WIS
E-Z Pass
A toll collection system that uses Radio Frequency Identification (RFID) technology to allow a driver to pass through a
tollbooth and pay the toll without stopping the vehicle. Typically, the driver prepays a month of access tolls and is issued a
transponder (a tag about the size of a deck of cards) that gets mounted on the inside of the windshield. When approaching a
toll, the E-ZPass driver passes through a special booth that has an antenna. The antenna emits a radio frequency (RF) field
that activates the driver's transponder, which in turn, sends back information about the driver's account to the antenna. The
toll is then deducted from the driver's prepaid account. E-Z Pass significantly cuts down on labor costs for toll collection
and keeps the lines of traffic moving faster.
WIS
FM
Frequency Modulation: A method of impressing data onto an alternating current (AC) wave by varying the instantaneous frequency
of the wave. This scheme can be used with analog or digital data.
WIS
Fractional T1
One or more of the 24 individual channels that a T1 line comprises, each channel supporting 64Kbits per second, and able to
carry voice or data traffic. Fractional access is the way most telephone companies deliver T1 service. WPD
Frequency-Shift Keying
FSK, a modulation technique used by modems in which two different frequencies in the carrier signal represent the binary
states of 0 and 1. Using FSK, a modem converts the binary data from a computer into a binary form in which logic 1 is
represented by an analog waveform at a specific frequency and logic 0 is represented by a wave at a different specific
frequency. WPD
GPRS
General Packet Radio Service: A standard for wireless communications delivering speeds up to 115 kilobits per second. GPRS is
an efficient use of limited bandwidth and is particularly suited for sending and receiving small bursts of data, such as
e-mail and Web browsing, as well as large volumes of data. WPD
Half-Duplex
Refers to transmission of data in one direction at a time. For example, a walkie-talkie is a half-duplex device because only
one party can talk at a time. In contrast, a telephone is a full-duplex device because both parties can talk simultaneously.
WPD
iDEN
Integrated Digital Enhanced Network: A wireless technology combining the capabilities of a digital cellular telephone, two-way
radio, alphanumeric pager, and data/fax modem in a single network. iDEN operates in the 800 MHz, 900MHz, and 1.5 GHz bands and
is based on Time Division Multiple Access (TDMA) and GSM architecture. It uses Motorola's Vector Sum Excited Linear Predictors
(VSELP) vocoder for voice compression and QAM modulation to deliver 64 Kbps over a 25 KHz channel.
WIS
In-Band Signaling
Integrated Services Digital Network (ISDN) normally uses a separate wire called the D-channel to set up calls and handle their
signals. In some locations, this third wire isn't available, and bandwidth must be "borrowed" from the other two data-carrying
B-channels. For Basic Rate Interface (BRI) service, this means that each B-channel is limited to 56 kbps throughput (instead
of 64 kbps with out-of-band signaling).
CNT
Incumbent Local Exchange Carrier
An ILEC, a telephone company providing local service when the Telecommunications Act of 1996 was enacted, in contrast with a
Competitive Local Exchange Carrier (CLEC), a company that competes with the already established local telephone business.
WPD
ISDN
Integrated Services Digital Network: An international communications standard for sending voice, video, and data over digital
telephone lines or normal telephone wires. ISDN supports data transfer rates of 64 Kbps (64,000 bits per second). There are
two types of ISDN: Basic Rate (BRI), consisting of two 64-Kbps B-channels and one D-channel for transmitting control
information; and Primary Rate ISDN, consisting of 23 B-channels and one D-channel (U.S.) or 30 B-channels and one D-channel
(Europe).
WPD
Kbps
Kilobits per second.
LATA
Local Access and Transport Area: A U.S. term that refers to a geographic region assigned to one or more telephone companies
for providing communication services. A connection between two telephone companies within the same region is referred to as
"intra-LATA." A connection between two local exchange carriers in different regions is called "inter-LATA," which is the same
as long-distance service. WPD
Local Number Portability
LNP, the ability of a telephone customer in the U.S. to keep the same local telephone number in switching to another local
telephone service provider. The Telecommunications Act of 1996 required that the local exchange carriers (LECs) in the 100
largest metropolitan markets provide this capability by the end of 1998. The idea is that by removing the personal
inconvenience of having to get a new phone number when changing service providers, competition among providers will be
increased.
WIS
Location Routing Number
LRN, in the U.S., a 10-digit number in a database called a Service Control Point (SCP) that identifies a switching port for a
local telephone exchange. LRN is a technique for providing Local Number Portability (LNP). Using LRN, when a phone number is
dialed, the local telephone exchange queries a routing database, usually the SCP, for the LRN associated with the subscriber.
WIS
Long-Distance Carrier
A telephone company that provides connections between local exchanges in different geographic areas. Referred to in the U.S.
as Interexchange Carriers (IXCs), long-distance carriers provides interlocal access and transport area (inter-LATA) service as
described in the Telecommunications Act of 1996. WIS
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Master/Slave
An architecture in which one device (the master) controls one or more other devices (the slaves). WPD
Mobitex
A wireless network architecture that specifies a framework for the fixed equipment necessary to support all the wireless
terminals in a packet-switched, radio-based communication system. The three major components of a Mobitex network are the
radio base station, the MX switch, and the network management center (NCC). Mobitex was developed in 1984 by Eritel, an
Ericsson subsidiary, for the Swedish Telecommunication Administration. WIS
Nagle's Algorithm
Named for its creator, John Nagle, used to automatically concatenate a number of small buffer messages. This process (called
nagling) increases the efficiency of a network application system by decreasing the number of packets that must be sent. WIS
Narrowband
Generally describes telecommunication that carries voice information in a narrow band of frequencies. More specifically, the
term is used to describe a specific frequency range set aside by the U.S. FCC for mobile or radio services, including paging
systems, from 50 cps to 64 Kbps.
WIS
Noise
In communications, interference (static) that destroys the integrity of signals on a line. Noise can come from a variety of
sources, including radio waves, nearby electrical wires, lightning, and bad connections. One of the major advantages of
fiber-optic cables over metal cables is that they are much less susceptible to noise. WPD
NT1
Network Terminating Unit 1: Using the Integrated Services Digital Network (ISDN) Basic Rate Interchange service, a device that
accepts a two-wire signal from the phone company and converts it to a four-wire signal that sends and receives to and from
devices within the home or business.
WIS
Nyquist's Theorem
Before sound as acoustic energy can be manipulated on a computer, it must first be converted to electrical energy (using a
transducer such as a microphone) and then transformed through an analog-to-digital converter into a digital representation.
This is all accomplished by sampling the continuous input waveform a certain number of times per second. The more often a wave
is sampled the more accurate the digital representation. Nyquist's Theorem (or Nyquist's Law), named in 1933 after scientist
Harry Nyquist, states that a sound must be sampled at least twice its highest analog frequency in order to extract all of the
information from the bandwidth and accurately represent the original acoustic energy.
WPD
OC Levels
Optical Carrier Levels: Specification of levels of the speed of fiber-optic networks conforming to the Synchronous Optical
Network (SONET) standard:
- OC-1 = 51.85 Mbps
- OC-3 = 155.52 Mbps
- OC-12 = 622.08 Mbps
- OC-24 = 1.244 Gbps
- OC-48 = 2.488 Gbps
- OC-192 = 9.952 Gbps WPD
OFDM
Orthogonal Frequency-Division Multiplexing: A method of digital modulation in which a signal is split into several narrowband
channels at different frequencies. The technology was first conceived in the 1960s and 1970s during research into minimizing
interference among channels near each other in frequency. WIS
Over-the-Air
OTA, a standard for transmission and reception of application-related information in a wireless communications system.
WIS
PCS
Personal Communications Service: The U.S. Federal Communications Commission (FCC) term used to describe a set of digital
cellular technologies being deployed in the U.S. PCS works over CDMA (also called IS-95), GSM, and North American TDMA (also
called IS-136) air interfaces. WPD
Phantom Dialing
In mobile wireless communication, a term describing what occurs when a user unintentionally presses a preprogrammed auto-dial
number on a cellular telephone keypad and unintentionally initiates a phone call. In the United States, phantom dialing is a
problem for 911 emergency centers, especially since many cell phones are configured to dial 911 (the emergency center)
automatically when either a "9" or a "1" is pressed. Phantom dialing can be prevented by using the cell phone's keyguard, a
feature that locks the keypad, or by disabling the auto-dial feature.
WIS
Predictive Dialer
Commonly used for telemarketing, surveys, appointment confirmation, payment collection, and service follow-ups, a telephone
control system that automatically calls a list of telephone numbers in sequence and screens out no-answers, busy signals,
answering machines, and disconnected numbers while predicting at what point a human caller will be able to handle the next
call. WIS
Protocol
An agreed-upon format for transmitting data between two devices. The protocol determines the following:
- The type of error checking to be used
- Data compression method, if any
- How the sending device will indicate that it has finished sending a
message
- How the receiving device will indicate that it has received a message
WPD
Provision
The term has a number of varied meanings when used in telecommunications:
- Providing telecommunication service to a user, including everything
necessary to set up the service, such as equipment, wiring, and
transmission
- A synonym for "configuring," as in "Telecommunication lines must
be correctly provisioned to work with the customer's equipment and
enabled for various options the customer has chosen."
- In a traditional telecommunications environment, there are three
separate types of provisioning: circuit provisioning, service
provisioning, and switch provisioning.
- In a wireless environment, "provisioning" refers to service activation
and involves programming various network databases with the
customer's information.
- In a slightly different sense, network provisioning systems are
intermediary systems that are used to provide customer services,
log transactions, carry out requests, and update files.
- Provisioning is the fourth step of the telecommunication sequence
called OAM&P: Operations, Administration, Maintenance, and
Provisioning. WIS
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Remote Access
The ability to log onto a network from a distant location. Generally, this implies a computer, a modem, and some remote access
software to connect to the network. Whereas "remote control" refers to taking control of another computer, "remote access"
means that the remote computer actually becomes a full-fledged host on the network.
WPD
Repeater
A network device used to regenerate or replicate a signal. Repeaters are used in transmission systems to regenerate analog or
digital signals distorted by transmission loss. Analog repeaters frequently can only amplify the signal, while digital
repeaters can reconstruct a signal to near its original quality. WPD
Ring Tone
(1) In the original usage, a tone returned by receiving equipment that tells a caller that the phone at that end is ringing.
The tone is sent back in between the ring sequence at the receiving end. The pulsing rate is one on, two off from a 3-phase
generator with each call using a single phase.
(2) Mobile phone users use the term to mean the ring that the caller hears. The proliferation of cellular telephones in recent
years has given rise to a wide variety of ring tones. These do not necessarily follow the intermittent ringdown signal. A
contemporary ring tone might consist of several bars of a familiar musical tune, played by an audio oscillator through a small
speaker. WIS
Roaming Service
In wireless telecommunication networks, the ability to move from one Access Point (AP) coverage area to another without
interruption in service or loss in connectivity. WIS
Service Level Agreement
An SLA, a contract between service provider and the end user stipulating the required level of service. An SLA should contain
a specified level of service, support options, enforcement or penalty provisions for services not provided, a guaranteed level
of system performance as relates to downtime or uptime, a specified level of customer support, what software or hardware is
provided, and the fee is. WPD
Short Message
Text messages no longer than 160 alphanumeric characters with no images or graphics, exchanged between mobile phones, fax
machines, or IP addresses in a telecommunications network.
WPD
Simplex
Transmission in only one direction. Note the difference between simplex and half-duplex. Half-duplex is two-way communication
in which only one party can transmit at a time. Simplex is one-way communication in which one party is the transmitter and the
other is the receiver. An example of simplex communications is an AM or FM radio, which can receive data from stations but
can't transmit data. WPD
Slot Time
In Ethernet and its Carrier Sense Multiple Access/Collision Detect (CSMA/CD) approach to managing which device can use the
communication link next, the amount of time a device waits after a collision before retransmitting. WIS
SMS
Short Message Service: Similar to paging, a service for sending short text messages to mobile phones. WPD
SNR
Signal-to-Noise Ratio: In analog and digital communication, a measure of signal strength relative to background noise. The
ratio is usually measured in decibels (dB). WIS
Slot Handoff
In cellular telephone communication, refers to the overlapping of repeater coverage zones, so that every cell phone set is
always well within range of at least one repeater (also called a base station). In some cases, mobile sets transmit signals
to, and receive signals from, more than one repeater at a time. WIS
Software-Defined Radio
SDR, wireless communication in which the transmitter modulation is generated or defined by software processing, and the
receiver uses software processing to recover the signal intelligence. To select the desired modulation type, the proper
programs must be run by microcomputers that control the transmitter and receiver. The ultimate goal is to provide a single
universal radio transceiver capable of playing the roles of cordless telephone, cell phone, wireless fax, wireless e-mail
system, pager, wireless videoconferencing unit, wireless Web browser, Global Positioning System (GPS) unit, and more. WIS
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Footnotes
CNT CNET Networks, Inc. Glossary.
<http://www.cnet.com/Resources/Info/Glossary/Terms/inbandsignaling.html> CNET Networks, Inc., 1995-2003.
IBM IBM Corporation. Glossary of Computing Terms.
<http://publib.boulder.ibm.com/infocenter/eserver/v1r3s/index.jsp?topic=/iphav/iphwglos.htm> IBM Corporation, 1999.
WPD Webopedia. Jupiter Media Corporation, 2003.
WIS WhatIs. <http://whatis.techtarget.com/> TechTarget.com, Inc., 2000.
