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Executive Editor:
Tricia
Parks; Complied by:
Kurt
Scherf Definitions Courtesy Of: The Consumer Electronics
Association, Efficient Networks Inc., Parks Associates, SBC
Communications Inc., webopedia.com, and whatis.com
Mastering industry acronyms can be a difficult task, so we have
compiled the following glossary in order to assist you in understanding
the meanings of various industry terms. If you have further questions on
a term or think something is missing from this list, please e-mail info@parksassociates.com.
3G
3G is an ITU specification for the third generation (analog cellular
was the first generation, digital PCS the second) of mobile
communications technology. 3G promises increased bandwidth, up to 384
Kbps when a device is stationery or moving at pedestrian speed, 128 Kbps
in a car, and 2 Mbps in fixed applications. 3G will work over wireless
air interfaces such as GSM, TDMA, and CDMA. The new EDGE air interface
has been developed specifically to meet the bandwidth needs of 3G.
10Base2
Also called Thin Ethernet, it uses a thin COAXIAL CABLE and daisy
chain configuration for 10 Mbps.
10Base5
Thick Ethernet, or 10Base5, uses a large COAXIAL CABLE to achieve 10
Mbps.
10Base-T
A 10 Mbps Ethernet LAN that runs over TWISTED-PAIR wiring. This
network interface was originally designed to run over ordinary
twisted-pair (phone wiring) but is predominantly used with CATEGORY 3 or
CATEGORY 5 cabling.
100Base-T
A 100 Mbps LAN that maintains backward compatibility with 10 BASE-T
networks running at 10 Mbps.
1000Base-T
Also called Gigabit Ethernet, this is a new standard that is being
defined to carry 1 Gigabit per second traffic a total distance of 100
meters using CAT5 TWISTED-PAIR cable.
ADSL (Asymmetric Digital Subscriber Line)
A technology that delivers data faster downstream than upstream;
therefore the use of the term ADSL. The fastest downstream rate is 8
Mbps, while the fastest upstream rate is 640 Kbps. The ADSL standard is
governed by the ITU and ANSI standards bodies. The two most common
implementations of ADSL are full-rate ADSL, governed by ITU G.992.1 and
ANSI T1.413, and the lower-speed ADSL, governed by ITU G.992.2. There is
no ANSI specification for G.LITE.
Many operators providing DSL service drop ship the customer premises
equipment to the SUBSCRIBER, for self-installation. The equipment
typically consists of the DSL modem/router, NIC card and filters to
filter out high-frequency signals so that both the voice and data can
share common inside wiring.
AMR (Automated Meter Reading)
The remote collection of consumption data from customers’ utility
meters using telephony, RF, powerline, and satellite communications
technologies.
API (Application Programming Interface)
A generic term for the routines, features, and associated rules which
allow computer programmers to build APPLICATIONS, and, APPLICATIONS
which exchange data with one another.
For example, when an operator’s VOD SUBSCRIBER elects to watch a
movie on demand, the video server and TV APPLICATION SERVER will
exchange information with the subscriber billing system based on the use
of the two systems’ APIs, so the fee for the viewing of the movie can be
billed to the SUBSCRIBER. The API ensures that the data is presented
from one system to the other in a format that the receiving system can
interpret or act upon.
Applications
Computer programs designed for use by end users and SUBSCRIBERs.
Examples include IPGs, VOD, electronics spreadsheets, and word
processing.
Application Server
Also called an appserver. A program that handles all
application operations between users and an organizations’ backend
business applications or databases. Application servers are typically
used for complex transaction-based applications. To support high-end
needs, an application server has to have built-in redundancy, monitors
for high-availability, high-performance distributed application services
and support for complex database access.
ASIC (Application Specific Integrated Circuit)
A chip designed for a specific application. Examples of an ASIC
application can be SDSL or other broadband solutions.
ATM (Asynchronous Transfer Mode)
A high-bandwidth, low-delay, connection-oriented packet-like
switching and multiplexing technique. Usable capacity is segmented into
53-byte fixed-size cells; each cell is presented to the network on a
start-stop basis, thus asynchronous. ATM is designed for use in
high-speed communications frameworks such as OC-3, OC-12 and SONET.
ATSC (Advanced Television Systems Committee)
The ATSC is a U.S.-based industry organization chartered to
establish digital broadcasting standards used in the U.S.
Bluetooth
A technology named after Harald Bluetooth, a 10th-century Viking
King who united Denmark under Christianity. This short-range RF solution
(10 centimeters to 10 meters) operates on a bandwidth of 2.4 GHz, an
unlicensed frequency worldwide. It is viewed primarily as a cable
replacement technology to link such devices as laptop computers and
personal digital assistants and mobile phones to headsets.
Broadband Network Operator
The business entity that provides information and entertainment
services to SUBSCRIBERs via a broadband network. These entities can be
TELCOS or independent private network providers utilizing the Telco’s
network. An operator may also choose to implement a network that is
separate and parallel to the public telephone network. Property
management firms that operate MDUs can also be broadband network
operators.
Broadcast
A simultaneous analog or digital transmission sent to all the
receivers in a network.
Bundle
A combination of more than one package of services, sold for a
single rate (price) by the BROADBAND NETWORK OPERATORS.
CA (Conditional Access)
A means of modifying a media stream, through encryption, scrambling
or other techniques, so that the SUBSCRIBER can view only the services
authorized by the operator for viewing by that SUBSCRIBER.
CableLabs
The dominant industry association for the U.S. cable television
industry. CableLabs has provided a number of reference specifications to
the industry, some of which have been adopted by international standards
organizations.
CAP (Carrierless Amplitude Modulation)
A single-carrier transmission technique used by some implementations of
ADSL.
Category 3 (Category 3 Wiring)
Consists of 4 pairs of TWISTED-PAIR wires used for medium speed
communications of up to 10 Megabits over distances of up to 100 meters.
The FCC has specified the use of a minimum of CAT3 wiring for telephones
in new home construction.
Category 4 (Category 4 Wiring)
Consists of 4 pairs of TWISTED-PAIR wires used for medium speed
communications of up to 16 Mbps over distances of up to 100 meters. It
is not in general use as its introduction was soon followed by the
development of CAT 5 cabling that provides greater throughput.
Category 5 (Category 5 Wiring)
Consists of 4 pairs of TWISTED-PAIR wires used for high-speed
communications of up to 100 Mbps over distances of up to 100 meters.
CDMA (Code-Division Multiple Access)
A digital cellular technology that uses SPREAD-SPECTRUM techniques.
Unlike competing systems, such as GSM, that use TDM, CDMA does not
assign a specific frequency to each user. Instead, every channel uses
the full available spectrum. Individual conversations are encoded with a
pseudo-random digital sequence. CDMA is a military technology first used
during World War II by the English allies to foil German attempts at
jamming transmissions. The allies decided to transmit over several
frequencies, instead of one, making it difficult for the Germans to pick
up the complete signal. Because Qualcomm Inc. created communications
chips for CDMA technology, it was privy to the classified information.
Once the information became public, Qualcomm claimed patents on the
technology and became the first to commercialize it.
CEBus (Consumer Electronics BUS®)
Known as EIA-600, it is a standard developed by the Electronics
Industry Association. The CEBus effort was initiated in 1984 as a
cross-industry effort among players in home controls, residential
wiring, and consumer electronics. The standard specifies home control
signals across a wide variety of network media.
Channel
The route by which a single stream of TV programming is distributed
from its originator to the SUBSCRIBER. The originator distributes the
content over a private network to the operator, which in turn, allocates
it to an assigned set of its own encoding and distribution resources.
Channel Assignment
The logical address for a stream of television programming, assigned by
the operator. In an IP TV deployment, channels are multicast to the edge
of the network, where they are presented for joins and leaves by
SUBSCRIBERS.
Circuit Switching
A switching system that establishes a dedicated physical communications
connection between endpoints through the network, for the duration of a
session. Contrasted with PACKET-SWITCHING in data communications
transmissions.
CISC (Complex Instruction Set Computer)
Pronounced sisk. Most personal computers use a CISC architecture,
in which the CPU supports as many as two hundred instructions. An
alternative architecture, used by many workstations and also some
personal computers, is RISC, which supports fewer instructions.
CLEC (Competitive Local Exchange Carrier)
A Local Exchange Carrier which is not the Incumbent (ILEC) or
market-leading LEC. CLECs compete on a selective basis for local
exchange service, and long distance, Internet access, and cable
TV/video-on-demand. They build or rebuild their own loops (wired or
wireless), and lease LOCAL LOOPs from ILECs at wholesale rates for
resale to end-users. CLECs include cellular/PCS providers, ISPs, IXCs,
CATV providers, CAPs, LMDS operators, and power utilities.
CO (Central Office)
The operations facility of a TELCO or BROADBAND NETWORK OPERATOR,
which acts as the switching hub and nerve center for a local subscriber
base. SUBSCRIBER lines are aggregated to the CO, for switching and
routing to other subscribers, and, into regional and interexchange wide
area telecommunications networks. In a television deployment, the CO may
become the co-location of the Head End.
Coaxial Cable
This cable consists of a single insulated copper wire surrounded by a
braided copper shield. Two types of coaxial cable are currently used in
LANs: 50-ohm cable is used for digital signaling, and 75-ohm cable is
used for analog and high-speed digital signaling. TIA-570-A (the
“standard” for residential structured wiring) calls for 75-ohm
quad-shielded coaxial cabling.
CODEC
A contraction of the terms Encoder and Decoder, used for the
compression of a media stream at the originating end and decompression
at the receiving end. This process enables more streams to be passed
through a given network path, simultaneously. Codecs are software
algorithms that may be distributed as software, or as software embedded
into a hardware chip or CONTENT PROCESSING SYSTEM.
Content-Processing System
A system of hardware and software which captures incoming analog,
digital, and encrypted media streams, and readies them for distribution
through the operator’s network. Among the processes done by a content
processing system are encoding, packet-shaping, and analog-to-digital
conversion.
Convergence
A term used to denote the combining of multiple communications media
types, such as voice, data, TV, movies, and the Internet, into a single
coordinated set of services for SUBSCRIBERs. Convergence is also used as
an identifying term for the industry of technology providers and service
operators collaboration to deliver multimedia services to SUBSCRIBERs
through communications networks.
CPE (Customer Premises Equipment)
Networking devices such as modems, POTS splitters, and other devices,
installed at a customer site, terminating the TELCO or BROADBAND NETWORK
OPERATOR network. The terminating device passes communications streams
into the SUBSCRIBER’s premises, to telephone sets, set-top boxes,
personal computers, routers, and other devices that present the streams
to the SUBSCRIBER for use.
Crosstalk
Interference on an analog line of an adjacent signal with the intended
receive signal. Crosstalk makes it hard to hear just the intended
signal, as there are multiple conversations on the line at once.
DAVIC (Digital Audio Video Council)
A worldwide association concerned with the interoperability of
audio-visual equipment and standardized interfaces. It is the source of
the DAVIC 1.3 specification, which incorporates the MHEG-5 content
decoder prevalent in the UK, as well as the use of the JAVA™ virtual
machine, in a set-top box environment.
DECT (Digital Enhanced Cordless Telecommunications)
A digital wireless telephone technology expected to make cordless
phones much more common in both businesses and homes in the future.
Formerly called the Digital European Cordless Telecommunications
standard because it was developed by European companies, DECT’s new name
reflects its global acceptance. Like another important wireless
standard, GSM, DECT uses TDMA to transmit radio signals to phones.
Whereas GSM is optimized for mobile travel over large areas, DECT is
designed especially for a smaller area with a large number of users,
such as in cities and corporate complexes. A user can have a telephone
equipped for both GSM and DECT (this is known as a dual-mode phone), and
they can operate seamlessly.
DHCP (Dynamic Host Configuration Protocol)
ATCP/IP protocol that allocates IP addresses automatically to any
DHCP client (any device attached to your network, such as your PC) so
that addresses can be reused when the client no longer needs them.
DMT (Discrete Multitone)
A technique used to carry multiple streams of data, each stream
being assigned a different frequency (subband), across a single carrier.
DOCSIS (Data Over Cable Service Interface Specification)
Now officially termed CableModem™, DOCSIS was developed by CABLELABS
and approved by the ITU in March 1998. The DOCSIS defines interface
standards for cable modems and supporting equipment. With certification
from CABLELABS, manufacturers will be able to produce cable modems for
retail, so consumers no longer have to depend on leased cable modems
from their cable providers. Other devices that recognize and support the
DOCSIS standard include HDTVs and Web-enabled set-top boxes for regular
televisions. DOCSIS specifies downstream traffic transfer rates between
27 and 36 Mbps over a RF path in the 50 MHz to 750+ MHz range, and
upstream traffic transfer rates between 320 Kbps and 10 Mbps over a RF
path between 5 and 42 MHz. But, because data over cable travels on a
shared loop, individuals will see transfer rates drop as more users gain
access.
DSL (Digital Subscriber Line/Loop)
A digital communications technology that uses TELCO copper wiring to
connect to the SUBSCRIBER. DSL uses a MODEM at each end of the
connection, one at the CO (or field cabinet) and another at the
subscriber premises. Subscriber DSL modems may be integrated devices
that also have routing, built-in ETHERNET, and other home networking
capabilities. Types of DSL listed elsewhere in this glossary are ADSL
and VDSL. Other types include HDSL and RADSL, which are not widely used
for television deployments.
DSLAM (DSL Access Multiplexer)
A system that aggregates multiple DSL SUBSCRIBER lines into a single
high-speed connection, usually and OC-3 or OC-12 optical trunk, back to
the operator’s facilities and the core network. The DSLAM can be
physically located within the CO or in a field cabinet.
DSP (Digital Signal Processor/Processing)
Refers to manipulating analog information, such as sound or
photographs, that has been converted into a digital form. DSP also
implies the use of a data compression technique. When used as a noun,
DSP stands for digital signal processor, a special type of coprocessor
designed for performing the mathematics involved in DSP. Most DSPs are
programmable, which means that they can be used for manipulating
different types of information, including sound, images, and video.
DSSS (Direct-Sequence Spread Spectrum)
Wireless LAN products are available in three different technologies
— DSSS, FHSS, and infrared. DSSS and FHSS are SPREAD-SPECTRUM techniques
that operate over the radio airwaves in the unlicensed ISM band
(industrial, scientific, and medical). DSSS uses a radio transmitter to
spread data packets over a fixed range of the frequency band.
DTG (Digital Television Group)
An organization dedicated to accelerating the deployment and
acceptance of DTV in the UK.
DTV (Digital Television)
The transmission of television signals using digital rather than
conventional analog methods.
DVB (Digital Video Broadcast)
A set of standards that defines digital broadcasting using existing
satellite, cable, and terrestrial infrastructures, used worldwide, but
not (yet) in the US. In the early 1990s, European broadcasters, consumer
equipment manufacturers, and regulatory bodies formed the European
Launching Group (ELG) to discuss introducing digital television (DTV)
throughout Europe. The ELG realized that mutual respect and trust had to
be established between members and later became the DVB Project. Today,
the DVB Project consists of more than 220 organizations in more than 29
countries worldwide. DVB-compliant digital broadcasting and equipment is
widely available and is distinguished by the DVB logo. Numerous DVB
broadcast services are available in Europe, North and South America,
Africa, Asia, and Australia. The term digital television is sometimes
used as a synonym for DVB. However, the ATSC standard is the digital
broadcasting standard used in the U.S.
DVD (Digital Versatile Disk)
ACD-sized laser disc used to store and playback high-quality audio
and video.
DVR (Digital Video Recording/Recorder)
See PVR.
Dynamic IP Address
Requesting DHCP computers receive a dynamic IP address (think
temporary phone number) for the duration of that Internet session or for
some other specified amount of time. Once the user disconnects from the
Internet, their dynamic IP address goes back into the IP address pool so
it can be assigned to another user. Even if the user reconnects
immediately, odds are they will not be assigned the same IP address from
the pool. To keep our telephone analogy going, using a dynamic IP
address is similar to using a pay phone. Unless there is a reason to
receive a call, the user does not care what number he or she is calling
from.
Ecosystem
A term used to convey the concept that a television delivery network
is an end-to-end system in which all of the elements are interdependent
and managed as a whole by the operator.
EDGE (Enhanced Data Rates for Global Evolution)
A technology that gives GSM and TDMA the capacity to handle services
for the third generation of mobile telephony. EDGE was developed to
enable the transmission of large amounts of data at a high speed, 384
Kbps. EDGE uses the same TDMA frame structure, logic channel, and 200kHz
carrier bandwidth as today’s GSM networks, which allows existing cell
plans to remain intact. (Definition courtesy of Ericsson)
EPG (Electronic Program Guide)
See IPG.
Ethernet
A LAN used to connect devices within a single building or campus.
Within the OSI Reference Model, Ethernet is defined at layer one
(physical) and layer two (data link). Based on Carrier Sense Multiple
Access/Collision Detection (CSMA/CD), Ethernet works by simply checking
the wire before sending data.
EPOC
An operating system from Psion Software designed specifically for
mobile, ROMbased computing devices. EPOC16 is a 16-bit version of the
operating system that has been available for several years and is
embedded in many handheld devices. EPOC32 is a 32-bit operating system
that supports preemptive multitasking. EPOC is competing head-to-head
with Windows CE in the growing PDA market.
FHSS (Frequency-Hopping Spread Spectrum)
Wireless LAN products are available in three different technologies
— DSSS, FHSS, and infrared. DSSS and FHSS are SPREAD-SPECTRUM techniques
that operate over the radio airwaves in the unlicensed ISM band
(industrial, scientific, and medical). FHSS uses a technique by which
the signal transmitted hops among several frequencies at a specific rate
and sequence as a way of avoiding interference.
Firewall
A combination of software and hardware that filters or blocks
traffic from a public network. A firewall renders parts of the private
network inaccessible and invisible to the public network. It prevents
unauthorized and/or unrecognized access.
Flash Memory
A special type of EEPROM that can be erased and reprogrammed in blocks
instead of one byte at a time. Many modern PCs have their BIOS stored on
a flash memory chip so that it can easily be updated if necessary. Such
a BIOS is sometimes called a flash BIOS. Flash memory is also popular in
MODEMs because it enables the modem manufacturer to support new
protocols as they become standardized.
G.Lite
Also known as DSL Lite and Universal ADSL, G.Lite is expected to become
the most widely installed form of DSL. It is essentially a smaller
bandwidth flavor of DSL, providing a data rate from 128 Kbps to 1.544
Mbps downstream and from 128 Kbps to 384 Kbps upstream.
GPRS (General Packet Radio Service)
A standard for wireless communications which runs at speeds up to
150 Kbps, compared with current GSM systems’ 9.6 kilobits. GPRS, which
supports a wide range of bandwidths, 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.
GSM (Global System for Mobile Communications)
One of the leading digital cellular systems. GSM uses narrowband
TDMA, which allows eight simultaneous calls on the same RF. GSM was
first introduced in 1991. As of the end of 1997, GSM service was
available in more than 100 countries and has become the de facto
standard in Europe and Asia.
HAVi (Home Audio Video Interoperability)
Announced in May 1998, HAVi is a consortium of consumer electronics
to specifically focus on the transfer of digital Audio/Video (AV)
content between HAVi devices as well as the processing (rendering,
record, play back) of this content by HAVi devices. Typical examples of
AV content are digital broadcasts received by a set-top box or content
produced by HAVi devices in the consumer’s home such as a digital video
recorder, a digital camera, or other devices via the IEEE-1394
“FireWire” Interface. The HAVi 1.0 specification defines elements, roles
and functions, and, ensures that their respective elements work together
in a home network.
HDSL (High Data-Rate Digital Subscriber Line)
ADSL service delivering 1.544 mbps, upstream and downstream, via two
copper twisted pairs. HDSL is used to provision T-1 services, and for
PBX, DLC, Internet servers, private networking, and for interconnecting
local and interexchange switches. Reach is limited to 12,000 feet.
HDTV (High-Definition Television)
A television display technology that provides picture quality
similar to 35 mm movies with sound quality similar to that of a compact
disc.
HFC (Hybrid Fiber Coax) Network
HFC network is a telecommunication technology in which optical fiber
cable and COAXIAL CABLE are used in different portions of a network to
carry broadband content (such as video, data, and voice). Using HFC, a
local CATV company installs fiber-optic cable from the cable head-end
(distribution center) to serving nodes located close to business and
residential users and from these nodes uses coaxial cable to individual
businesses and homes. An advantage of HFC is that some of the
characteristics of fiber optic cable (high bandwidth and low noise and
interference susceptibility) can be brought close to the user without
having to replace the existing COAXIAL CABLE that is installed all the
way to the home and business.
Home Network
An in-home network means that through the use of microprocessors and
common software languages, different household products and systems will
communicate with each other. The key in this definition is that devices
are capable of true two-way signaling.
Home Plug & Play™
The Home Plug & Play standard allows CAL to be transported by
multiple transport protocols, including IEEE 1394.
HomePlug Powerline Alliance
Officially launched on April 10, 2000, this alliance of companies is
seeking to standardize a 10 Mbps home networking solution that will
utilize electrical wiring.
HomePNA (Home Phoneline Networking Alliance)
Publicly announced in June 1998, HomePNA has launched two versions
of a networking technology that utilizes the existing phonelines in the
home to network PCs and other devices. The group endorsed a 1 Mbps
technology from Tut Systems Inc. in 1998. In 1999, the consortium
endorsed a 10 Mbps technology jointly proposed by Broadcom Corp. and
Lucent Technologies Microelectronics Group. The alliance now totals more
than 150 companies.
HomeRF
Publicly launched in March 1998, HomeRF has developed a technology
called SWAP, or Shared Wireless Access Protocol. Utilizing the 2.4 GHz
unlicensed bandwidth, first-generation HomeRF products will deliver
wireless data and voice services between and among PCs, cordless
telephone handsets, and other consumer electronics products at a
throughput of 1.6 Mbps. Relying on FHSS technology, SWAP is a merger
between wireless LAN technologies and DECT.
HTML (Hypertext Markup Language)
The language of the Internet’s World Wide Web, allowing publishing over
the Internet using standardized instructions and methods for the
presentations of text and graphics to the viewer. HTML is interpreted by
Web browsers, which, although associated with personal computers, are
widely used within television set-top boxes as the presentation
environment for TV and WALLED GARDEN content. The specification for HTML
is controlled by an open standards body called the W3C, the Worldwide
Web Consortium.
IEEE (Institute of Electrical and Electronics Engineers)
A standards organization.
IEEE 1394
A technology that also goes by the name of FireWire™ (Apple Computer)
and i.LINK™ (Sony), this high-speed hardware and software-based
networking solution delivers data at rates of between 100 and 800 Mbps.
Designed for technologies requiring isochronous data.
IEEE 802.3
See ETHERNET.
IEEE 802.11b
“High-Rate” radio frequency networking technology developed by the IEEE.
Most wired networks conform to 802.3, the specification for CSMA/CD-based
Ethernet networks, or 802.5, the specification for token ring networks.
802.11b utilizes the license-free bandwidth of 2.4 GHz, and most
products utilize DSSS. Further 802.11 variants include:
- 802.11a: a 54 Mbps solution utilizing the 5 GHz space;
- 802.11e: an enhancement to the MAC for QoS; and
- 802.11g: OFDM-based variant that effectively doubles data
throughput of 802.11b.
IGMP (Internet Group Management Protocol)
A set of rules governing the registration of users with a multicast
group.
ILEC (Incumbent Local Exchange Carrier)
Not to be confused with Independent TELCOs, which were never part of
the Bell system. An ILEC is a Local Exchange Carrier which, when
competition begins (per the 1996 Telecommunications Act), has the
dominant position in the market. In other words, the original carrier in
the market prior to the entry of competition.
Information Appliance
A relatively low-cost, easy-to-use, reliable, special-purpose device
that obtains and presents, captures and reports, and/or stores and
manages various types of information in order to bring the benefits of
the Internet to consumers.
IP (Internet Protocol)
A network layer protocol in the TCP/IP stack, provides features for
addressing, type of service specification, fragmentation and reassembly,
and security.
IPG (Interactive Program Guide)
A television user interface that allows SUBSCRIBERs to review and select
programs to watch on TV using the remote control. The IPG data
(METADATA) is housed at the head-end or CO, but is presented to the
SUBSCRIBER visually via a program residing in the set-top box. IPG
METADATA is obtained from licensors including Gemstar TV GUide, Tribune,
TV Data and SourceMedia, from the content provider itself, or may be
created by the operator. Some IPGs are designed to host data for
programs as far as two weeks into the future, some are not.
IP Multicast (Internet Protocol Multicast)
A technique that lets a network simultaneously deliver a single
stream of content (single copy of the data stream) to multiple locations
over an IP network. Those that desire to receive this multicast join the
multicast, leaving it when finished.
IP Multicast Address(es)
The IP devices which have joined an IP MULTICAST stream.
IP Multicast Group
An arbitrary collection of SUBSCRIBERs interested in receiving the same
multicast stream. Those interested in receiving the stream join the
stream via IGMP.
IP Telephony (Internet Protocol Telephony)
A general term for the technologies that use the IP’s
packet-switched connections to exchange voice, fax, and other forms of
information that have traditionally been carried over the dedicated
circuit-switched connections of the public-switched telephone network (PSTN).
Using the Internet, calls travel as packets of data on shared lines,
avoiding the tolls of the PSTN. The challenge in IP telephony is to
deliver the voice, fax, or video packets in a dependable flow to the
user. Much of IP telephony focuses on this challenge.
IP Television
The offering of television and associated advanced media services using
the same packet-based delivery system used for the Internet.
ISDN (Integrated Services Digital Network)
A communication protocol offered by telephone companies that permits
telephone networks to carry data, voice, and other traffic. DSL is
replacing ISDN because it can typically provide a faster connection.
ISDN continues to be a popular technology in Europe and parts of the
Pacific Rim.
ISO (International Organization for Standardization)
An international standards body based in Geneva, Switzerland. Best
known for the seven-layer OSI REFERENCE MODEL.
Isochronous
From the Greek for “equal” and “time,” isochronous data transfer
pertains to processes that require timing coordination to be successful,
such as voice and digital video transmission.
ITU (International Telecommunications Union)
An international standards body based in Geneva, Switzerland. The
ITU-T, formerly known as the CCITT, is the standardization sector which
develops worldwide standards for telecommunications. ITU-R is the sector
devoted to radio and television.
Java™
A high-level programming language developed by Sun Microsystems.
Java was originally called OAK and was designed for handheld devices and
set-top boxes. Oak was unsuccessful, so in 1995 Sun changed the name to
Java and modified the language to take advantage of the burgeoning World
Wide Web. Java is a general-purpose programming language with a number
of features that make the language well suited for use on the World Wide
Web. Small Java applications are called Java applets and can be
downloaded from a Web server and run on your computer by a
Java-compatible Web browser, such as Netscape Navigator or Microsoft
Internet Explorer.
For television, a compact version of Java, called Personal Java, has
been adopted within the DVB-MHP specification as its standard execution
platform for television set-top boxes, and it is more widely used
outside the US than within.
Jini™
Software from Sun Microsystems that seeks to simplify the connection
and sharing of devices, such as printers and disk drives, on a network.
Currently adding such devices to a computer or network requires
installation and boot-up, but a device that incorporates Jini will
announce itself to the network, provide some details about its
capabilities, and immediately become accessible to other devices on the
network. Under this technology it would be possible to create
distributed computing, whereby capabilities are shared among the
machines on a common network. This would allow users to access the power
and features of any device on the network and would free the desktop
computer from holding all the memory, storage, and processing power it
needs for any job. For example, if a disk drive on a network had Jini
capabilities, any computer on that network could use the drive as though
it were its own. Because Jini has the potential to make operating
systems incidental to the power of networks, some have seen Jini as an
attempt to reduce the influence of Windows.
LAN (Local-Area Network)
A computer network that spans a relatively small area. Most LANs are
confined to a single building or group of buildings. However, one LAN
can be connected to other LANs over any distance via telephone lines and
radio waves. A system of LANs connected in this way is called a WAN.
Latency
In networking, the time it takes a packet to travel from source to
destination. Together, latency and bandwidth define the speed and
capacity of a network.
Layer
Once upon a time, the ISO designed an OSI REFERENCE MODEL for all
network developers on our planet. The seven “layers” of the OSI model
are:
- physical: electrical and mechanical functions;
- data link: detecting and correcting errors;
- network: routing processes;
- transport: initiating and releasing connections;
- session: handling transmission errors;
- presentation: formatting data; and
- application: interface with network services.
LMDS (Local Multipoint Distribution Service)
A form of broadband fixed wireless system that operates in the 27-31 GHz
range.
Local Loop
A generic term for the connection between the customer premises (home or
office) and the provider’s serving Central Office.
LONWORKS®
This home and building control standard was initiated by Echelon Corp.
in the late 1980s. Like CEBus, the standard includes communication
protocols that can be delivered over multiple media. The LONWORKS
system includes all the components necessary to implement open
interoperable control systems that can be easily and seamlessly
integrated within a home — and beyond. This LONWORKS
system includes all the necessary hardware and software components for
implementing complete end-to-end control systems. LONWORKS
was approved as EIA-709 in 1998. Echelon has partnered with such
Internet giants as Cisco Systems Inc. to initiate IP-based home control
solutions.
MAC Address (Media Access Control)
A MAC (layer two) address is required for every port or device that
connects to a LAN. MAC addresses allow framing and error detection. They
are six bytes long and are also known as hardware addresses and physical
addresses.
MDU (Multiple-Dwelling Unit)
A catch-all term that represents a collection of residential or business
locations that can be served by broadband-based services. Examples of
“MDUs” include master-planned communities wherein the management company
is also the provider of entertainment and communication services (i.e.,
TV and telephone services). Others are apartment complexes. In the
broadest use of the definition, the term MDU can include hospitality
businesses such as hotels, casinos, and cruise ships.
Metadata
Data about data. One example is the information about programming
that goes into an IPG. Another example is the data that defines the
format of billing information that is passed from a TV APPLICATION
SERVER, to the SUBSCRIBER billing system, such as field definitions.
MHEG-5
A content presentation specification within the DAVIC API, which is
widely adopted by operators in the UK.
MHP (Multimedia Home Project)
A specification developed by the DVB for interactive television
set-top boxes. The execution environment uses Sun Microsystems’ Java
technology.
Middleware
A term used to describe separate products that serve as the glue between
two APPLICATIONs. Middleware is sometimes called plumbing because it
connects two sides of an APPLICATION and passes data between them.
MMDS (Multichannel Multipoint Distribution Service)
A form of broadband fixed wireless system that operates in the 2 GHz
range. Also known as "wireless cable."
Modem
A term which is actually based on the function of the device itself — a
MOdulator/DEModulator. A modem converts analog waveforms into digital
data and vice versa.
Modulation
The process whereby an electrical carrier wave is altered to facilitate
the transmission of a signal.
MPEG (Motion Picture Experts Group)
This is an industry organization whose goal is to develop standards and
specifications for the encoding, transmission, and decoding of video
information over various media and network technologies.
MP3
Is the file extension for MPEG, audio layer 3. Layer 3 is one of three
coding schemes (layer one, layer two, and layer three) for the
compression of audio signals. The result in real terms is layer 3
shrinks the original sound data from a CD (with a bitrate of 1411.2 Kbps
of stereo music) by a factor of 12 (down to 112-128 Kbps) without
sacrificing sound quality.
MPEG1
Compression scheme for full-motion video. Compression algorithm
introduced by MPEG in 1991, the common goal of MPEG is to compress 7.7
Megabytes down to about 150 Kilobytes. The MPEG1 is designed to provide
a resolution of 352 by 240 pixels at 30 frames per second. It was
designed for use with narrowband systems and CD-ROMs for
progressive-scan moving pictures.
MPEG2
A digital moving picture format used for broadcast quality systems using
variable bit rate encoding and interlacing. Typical MPEG2 rates are
between 2.5 and 5 Mbps, with 3 Mbps being a typical frame of reference.
Designed to provide a resolution of 720 by 480 pixels at 30 frames per
second.
Multicast
A media (packet) stream that is copied and sent to multiple authorized
SUBSCRIBERS (network addresses). Multicast addresses are group
addresses. Typical uses include the updating of mobile personnel from a
home office and the periodic issuance of online newsletters.
NAT (Network Address Translation)
The translation of an IP ADDRESS used within one network to a
different IP ADDRESS known within another network. Reduces the need for
globally unique IP ADDRESSes. NAT allows a business to use a single IP
ADDRESS in its communication with the outside world.
Node
This refers to an endpoint of a network connection, or a junction
common to two or more lines in a network. Nodes can be processors,
controllers, or workstations.
"No-New-Wires"
A term commonly used to include any networking technology that
doesn’t require new wiring to be installed into typical North American
homes.
NVOD (Near-Video-On-Demand)
A television programming technique used by operators to devote
multiple channels to a single movie, staggering the start times so the
SUBSCRIBER need not wait as long for the next showing to start.
OSGi (Open Services Gateway Initiative)
Launched in early 1999, OSGi is an industry group working to define
and promote an open standard for connecting the coming generation of
smart consumer and small-business appliances with commercial Internet
services. The Open Services Gateway specification will provide a common
foundation for ISPs, network operators, and equipment manufacturers to
deliver a wide range of e-services via gateway servers running in the
home or remote office.
OSI (Open Systems Interconnection) Reference Model
An architectural conceptual model for communications networks,
developed by the ISO in cooperation with the ITU. It consists of seven
LAYERS, defining all aspects of a communications network, and the
conveyance and control of communications-based services, over the
network.
Packet Switching
The process of routing and transferring data by means of addressed
packets so that a channel is occupied during the transmission of the
packet only, and upon completion of the transmission, the channel is
made available for the transfer of other traffic.
Parental Controls
A term used to connote the ability for programmers to shield viewers
from inappropriate content. In the US, both movies and television
programming are subject to content rating systems. Designers of TV
delivery systems must factor these content rating systems into their
systems and deployments, as SUBSCRIBERs have come to expect these
systems. The content rating itself is a part of the METADATA used by
IPGs and VOD systems.
PBX (Private Branch Exchange)
A private telephone network used within an enterprise. Users of the
PBX share a certain number of outside lines for making telephone calls
external to the PBX. Most medium-sized and larger companies use a PBX
because it’s much less expensive than connecting an external telephone
line to every telephone within the organization.
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. Some of the most important
distinguishing features of PCS systems are:
- They are completely digital;
- They operate at the 1900 MHz frequency range;
- They can be used internationally; and
- PCS is a second-generation mobile communications technology.
PLC (Powerline Carrier Communications)
Powerline carrier that uses the existing power cabling found in homes
and commercial buildings to connect devices. Speeds range from 60 bps to
over 10 Mbps. Depending on the technology, it is used for controls and
data networking.
POTS (Plain Old Telephone Service)
This term commonly refers to standard telephony, as in placing and
receiving telephone calls. This is more or less interchangeable with
PSTN (Public Switched Telephone Network). APOTS splitter enables both
DSL digital data and standard telephone analog transmissions to share a
single connection.
PPV (Pay-Per-View) Programming
TV programming services, such as live events or pre-recorded
programs, that are multicast only to those subscribers that have been
authorized by the operator, usually meaning that the SUBSCRIBERs have
paid for the right to view the event in advance. In order for the
subscriber to place and confirm the order, a return-path is required
back to the operator.
PVR (Personal Video Recording/Recorder)
Broadly speaking, PVR enables the subscriber to “time-shift” the
live television viewing experience in a way similar to the VCR, by
pausing, rewinding, fast forwarding, and recording for later viewing. To
do this, content must be stored. Storage can be client-side (stored on a
hard disk in the set-top box), or, server-side (stored by a video server
at the head-end that has been designed for this purpose). More
sophisticated PVR offerings complement the viewing experience with an
IPG and other enhancements. PVR is also a reference to the consumer
electronics device that enables PVR service for the subscriber. Some
PVRs are implemented within stand-alone devices, others are integrated
within a multifunctional TV set-top box.
QoS (Quality of Service)
A networking term that specifies a guaranteed throughput level. One
of the biggest advantages of ATM over competing technologies such as
Frame Relay and Fast Ethernet is that it supports QoS levels. This
allows ATM providers to guarantee to their customers that end-to-end
LATENCY will not exceed a specified level.
RBOC (Regional Bell Operating Company)
An all-inclusive term for each of the seven telephone companies that
were created after AT&T’s divestiture. Due to merger and acquisition
activity, the original seven are currently four: SBC Communications
(formerly Pacific Telesis, Southwestern Bell and Ameritech), BellSouth,
Verizon (formerly NYNEX and BellAtlantic), and Qwest (formerly U S
West).
RF (Radio Frequency)
Refers to alternating current (AC) having characteristics such that,
if the current is input to an antenna, an electromagnetic (EM) field is
generated suitable for wireless broadcasting and/or communications.
These frequencies cover a significant portion of the electromagnetic
radiation spectrum, extending from nine kilohertz (9 kHz), the lowest
allocated wireless communications frequency (it’s within the range of
human hearing), to thousands of gigahertz (GHz).
RG (Residential Gateway)
A residential gateway is a network interface device that terminates
a WAN and connects to end-user devices directly or through a home
network. In addition to features common to any gateway, it should
include an embedded broadband modem, dynamic routing capacity, security
features, and direct or indirect support for home networking.
Return Path
The return path is the communications connection carrying signaling from
the SUBSCRIBER, back to the operator. A return path is required for true
interactive television, and, for on-demand services such as PAY-PER-VIEW
PROGRAMMING, VOD, and games.
For cable and satellite TV operators, the return path takes the form
of a second connection to the set-top box (such as a telephone line); it
is not an issue for broadband network operators and TELCOS using IP
networks and/or xDSL, where a return path is inherent in the
communications network.
RG59
RG59 is an older form of COAXIAL CABLE installed in most homes built
before the 90s. It has a 20-gauge center conductor and is not as well
shielded as RG6. It is also smaller in overall diameter. It uses an “F”
style connector.
RG6
RG6 cable is now specified for most new COAXIAL CABLING in homes. It
uses an 18-gauge center conductor and typically is quad-shielded (4
shields: 2 foil and 2 braids). It uses an “F” connector which can be
connected to those used by RG59.
RISC (Reduced Instruction Set Computer)
Pronounced risk. A type of microprocessor that recognizes a
relatively limited number of instructions. Until the mid-1980s, the
tendency among computer manufacturers was to build increasingly complex
CPUs that had ever-larger sets of instructions. At that time, however, a
number of computer manufacturers decided to reverse this trend by
building CPUs capable of executing only a very limited set of
instructions. One advantage of reduced instruction set computers is that
they can execute their instructions very quickly because the
instructions are so simple. Another, perhaps more important advantage is
that RISC chips require fewer transistors, which makes them cheaper to
design and produce. Since the emergence of RISC computers, conventional
computers have been referred to as CISCs. There is still considerable
controversy among experts about the ultimate value of RISC
architectures. Its proponents argue that RISC machines are both cheaper
and faster, and are thus the machines of the future. Skeptics note that
by making the hardware simpler, RISC architectures put a greater burden
on the software, which is unnecessary because conventional
microprocessors are becoming increasingly fast and cheap anyway. To some
extent, the argument is becoming moot because CISC and RISC
implementations are becoming more and more alike. Many of today’s RISC
chips support as many instructions as yesterday’s CISC chips. And
today’s CISC chips use many techniques formerly associated with RISC
chips.
RJ-11
Six-conductor modular jack used with four-wire cabling. Most common
phone jack in the world and is used commonly on phones, modems, and fax
machines.
RJ-45
Eight-pin connector used to attach data transmission devices to standard
telephone wiring. Commonly used in 10Base-T connections.
Router
A router is a network layer device that uses one or more algorithms
to determine the optimal path along which data should be forwarded.
Routers forward packets from one network to another based on network
layer information. Routers are occasionally called gateways, but
traditional gateways do not translate data.
SCP (Simple Control Protocol)
A lightweight network and control protocol for devices that have
limited processing and memory resources and operate over limited
bandwidth.
SDSL (Symmetrical Digital Subscriber Line)
A form of DSL, delivering 1.544 Mbps both downstream and upstream
over a single copper pair. Range is up to 22,000 feet, depending on the
gauge of the wiring.
Spread Spectrum
Spread spectrum is a form of wireless communications in which the
frequency of the transmitted signal is deliberately varied — this
results in a much greater bandwidth than the signal would have if its
frequency were not varied.
Splitterless DSL
Also refered to as G.Lite. See ADSL.
Static IP Address
A static IP is a dotted quad number that is assigned to a computer
by and Internet Service Provider (ISP) to be its permanent address on
the Internet. Computers use IP addresses to locate and talk to each
other on the Internet, much the same way people use phone numbers to
locate and talk to one another on the telephone. It would be simple if
every computer that connects to the Internet could have its own static
IP number, but when the Internet was first conceived, the architects
didn’t foresee the need for an unlimited number of IP addresses.
Consequently, there are not enough IP numbers to go around. To get
around that problem, many Internet service providers limit the number of
static IP addresses they allocated, and economize on the remaining
number of IP addresses they possess by temporarily assigning an IP
address to a requesting DHCP computer to form a pool of IP addresses.
The temporary IP address is called a dynamic IP address.
Structured Wiring
A system of low-voltage wires designed to carry electronic signals
throughout a home.
Subscriber
The residential or business end-user customer at the receiving end
of services from the TELCO or BROADBAND NETWORK OPERATOR.
SWAP (Shared Wireless Access Protocols)
The SWAP specification defines a new common interface that supports
wireless voice and data networking in the home (HomeRF).
T-1
A Bell system term for a digital carrier facility used for
transmission of data through the telephone hierarchy at a transmission
rate of 1.544 Mbps.
TDMA (Time Division Multiple Access)
A technology for delivering digital wireless service using time-division
multiplexing (TDM). TDMA divides a radio frequency into time slots and
then allocates slots to multiple calls. In this way, a single frequency
can support multiple, simultaneous data channels. TDMA is used by the
GSM digital cellular system.
Telco
Telephone company.
Telemetry
Most commonly associated with RG applications that deliver energy
utility-based services, the word is derived from “telemeter,” an
electrical apparatus for measuring a quantity (as pressure, speed, or
temperature), transmitting the result to a distant station, and there
indicating or recording the quantity measured. For purposes of energy
utilities, telemetry delivers real-time price and usage information, and
enables the service providers to better manage load.
Transaction
An event reflecting the use of an item in an interactive television
system. It does not necessarily have to have a price associated with it,
nor do funds necessarily change hands. It is always tracked by
APPLICATION SERVERS within the television delivery system.
Twisted Pair
A common form of copper cabling used for telephony and data
communications. It consists of two copper lines twisted around each
other; the twisting protects the communications from electromagnetic
frequency and radio frequency interference.
UMTS (Universal Mobile Telecommunications System)
Also called “third-generation (3G),” broadband, packet-based
transmission of text, digitized voice, video, and multimedia at data
rates up to and possibly higher than 2 Mbps, offering a consistent set
of services to mobile computer and phone users no matter where they are
located in the world. Based on the GSM communication standard, UMTS,
endorsed by major standards bodies and manufacturers, is the planned
standard for mobile users around the world by 2002. Once UMTS is fully
implemented, computer and phone users can be constantly attached to the
Internet as they travel and, with roaming service, have the same set of
capabilities no matter where they travel. Users will have access through
a combination of terrestrial wireless and satellite transmissions. Until
UMTS is fully implemented, users can have multimode devices that switch
to the currently available technology (such as GSM 900 and 1800) where
UMTS is not yet available.
Today’s cellular telephone systems are mainly circuit-switched, with
connections always dependent on circuit availability. PACKET-SWITCHED
connection, using the IP, means that a virtual connection is always
available to any other end point in the network. It will also make it
possible to provide new services, such as alternative billing methods
(pay-per-bit, pay-per-session, flat rate, asymmetric bandwidth, and
others). The higher bandwidth of UMTS also promises new services, such
as videoconferencing. UMTS promises to realize the Virtual Home
Environment (VHE) in which a roaming user can have the same services to
which the user is accustomed when at home or in the office through a
combination of transparent terrestrial and satellite connections.
Unicast
A content stream directed to a specific SUBSCRIBER (IP network
address), and no other. VOD utilizes unicast techniques.
Unified Messaging
Unified messaging (sometimes referred to as the unified messaging
system or UMS) is the handling of voice, fax, and regular text messages
as objects in a single mailbox that a user can access either with a
regular e-mail client or by telephone. PC users can open and play back
voice messages, assuming their PC has multimedia capabilities. Fax
images can be saved or printed. A user can access the same mailbox by
telephone. In this case, ordinary e-mail notes in text are converted
into audio files and played back. Unified messaging is particularly
convenient for mobile business users because it allows them to reach
colleagues and customers through a PC or telephone, whichever happens to
be available. Some services offer worldwide telephone access.
UPnP (Universal Plug And Play)
An architecture for pervasive peer-to-peer network connectivity of
PCs of all form factors, intelligent appliances, and wireless devices.
UPnP is a distributed, open networking architecture that leverages
TCP/IP and the Web to define a set of common interfaces that describe
devices and services, allow automatic discovery when a device is plugged
into a network, and allow other devices and people to use them without
complicated setup or configuration.
UTP (Unshielded Twisted Pair)
UTP cabling is used in a variety of networks and does not require
the fixed spacing between connections that is necessary with COAXIAL
CABLE.
UWB (UltraWideBand)
UWB radio (also known as digital pulse wireless) is a revolutionary
wireless technology for transmitting large amounts of digital data over
a wide spectrum of frequency bands with very low power. UWB radio not
only can carry a huge amount of data over a short distance (up to 230
feet) at very low power (less than 0.5 milliwatts), but has the ability
to carry signals through doors and other obstacles that tend to reflect
signals at more limited bandwidths and a higher power. UWB radio can be
compared with another short-distance wireless technology, Bluetooth,
which is a proposed standard for connecting handheld wireless devices
with other similar devices and with desktop computers. In the U.S., the
Federal Communications Commission (FCC) is considering permitting use of
the technology to early applicants. The Federal Aviation Authority (FAA)
is concerned about possible interference over aviation channels. The
technology’s supporters insist that the power is so low that there is
little or no possibility of interference. Time Domain, Radar Inc., and
Zircon are three companies that have applied to the FCC for an exemption
from spectrum rules so that they can use the new technology.
VDSL (Very High Data Rate Digital Subscriber Line)
A technology that delivers 13 to 52 Mbps downstream and 1.5 to 2.3
Mbps upstream over a single copper twisted-pair. The operating range of
VDSL is limited to 1,000 to 4,500 feet (304.8 to 1,372 meters) from the
CO. VDSL is championed by several industry organizations, most notably
the FS-VDSL. The international standard most closely related to VDSL is
the Full Services Access Networks (FSAN) standard, ITU G.983.1.
VHN (VESA Home Networking Committee)
A committee of the Video Electronics Standards Association, the VHN
was established in 1995 to develop an open industry architecture
standard for digital home networks.
VoATM (Voice Over ATM)
Enables a ROUTER to carry voice traffic (for example, telephone
calls and faxes) over an ATM network through a special encapsulation for
multiplexed voice.
VOD (Video-On-Demand)
The ability to activate a stored or live motion picture stream, on
demand, delivered to a SUBSCRIBER over an operator’s network. Unlike
PAY-PER-VIEW, VOD represents a private showing, and may be likened to
the rental of a video, but without the inconvenience of driving to the
store. VOD is a term used to connote the delivery (unicast) of a movie
or video from a centralized video server, to individual SUBSCRIBERs.
The SUBSCRIBER initiates the viewing at any time. Many SUBSCRIBERs
can unknowingly be viewing the same movie simultaneously, which forces
the operator to plan for peaks and valleys in demand. Different video
servers deal with this problem in different ways through scaling,
movement of content to the edge of the network, or even caching it to a
hard-disk on the SUBSCRIBER’s set-top box.
VoDSL (Voice Over DSL)
Expands on existing DSL service capabilities by providing up to four
derived voice channels over the ADSL line and primary POTS line.
VoFR (Voice Over Frame Relay)
Enables a ROUTER to carry voice traffic (for example, telephone
calls and faxes) over a Frame Relay network after segmenting and
encapsulating it.
VoIP (Voice Over IP)
Voice delivered using the IP. It is a term used in IP TELEPHONY for
a set of facilities for managing the delivery of voice information using
the IP. In general, this means sending voice information in digital form
in discrete packets rather than in the traditional circuit-committed
protocols of the public switched telephone network (PSTN). A major
advantage of VoIP and Internet telephony is that it avoids the tolls
charged by ordinary telephone service.
VPN (Virtual Private Network)
A network constructed by using public wires to connect nodes. For
example, a number of systems enable creation of networks using the
Internet as the medium for transporting data. These systems use
encryption and other security mechanisms to ensure that only authorized
users can access the network and that the data cannot be intercepted.
Walled Garden
A Walled Garden is a captive environment designed to keep the
SUBSCRIBER within the operator’s own services. The two classic examples
of Walled Gardens are cable and satellite television services, and
Internet Web portals. With cable and satellite, the SUBSCRIBER receives
only what the operator can offer, regardless of the local and network
programming available in the SUBSCRIBER's service area. With Web
portals, users are admitted into subject areas through menus. Those
subject areas are filled with content from business affiliates, which
pay the portal operator when an end user clicks to its content. In the
interactive TV context, a Walled Garden is a carefully designed and
controlled user interface with the above characteristics, designed for
rendering within the constraints of the middleware residing within the
subscriber’s set-top box.
WAN (Wide-Area Network)
Private network facilities, usually offered by public telephone
companies but increasingly available from alternative access providers
(sometimes called CAPs), that link business networks.
WAP (Wireless Application Protocol)
WAP is a secure specification that allows users to access
information instantly via handheld wireless devices such as mobile
phones, pagers, two-way radios, smart phones, and communicators.
WAP supports most wireless networks. These include CDPD, CDMA, GSM,
PDC, PHS, TDMA, FLEX, ReFLEX, iDEN, TETRA, DECT, DataTAC, and Mobitex.
WAP is supported by all operating systems. Ones specifically engineered
for handheld devices include PalmOS, EPOC, Windows CE, FLEXOS, OS/9, and
JavaOS. WAPs that use displays and access the Internet run what are
called microbrowsers with small file sizes that can accommodate the low
memory constraints of handheld devices and the low bandwidth constraints
of a wireless-handheld network. Although WAP supports HTML and XML, the
WML language (an XML application) is specifically devised for small
screens and one-hand navigation without a keyboard. WML is scaleable
from two-line text displays up through graphic screens found on items
such as smart phones and communicators. WAP also supports WMLScript. It
is similar to JavaScript, but makes minimal demands on memory and CPU
power because it does not contain many of the unnecessary functions
found in other scripting languages. Because WAP is fairly new, it is not
a formal standard yet. It is still an initiative that was started by
Unwired Planet, Motorola, Nokia, and Ericsson.
WECA (Wireless Ethernet Compatibility Alliance)
WECA's mission is to certify interoperability of Wi-Fi™ (IEEE 802.11
High Rate) wireless LAN products and to promote Wi-Fi™ as the standard
for wireless LAN deployments across all market segments.
WML (Wireless Markup Language)
An XML language used to specify content and user interface for WAP
devices; the WAP forum provides a DTD for WML. WML is supported by
almost every mobile phone browser around the world. WML pages are
requested and served in the same way as HDML pages. For Web servers to
serve WML pages, they must contain the text/vnd.wap.wml mime type.
X-10
A powerline carrier protocol created by X10 Ltd. in 1978 that carries
control signals across standard electrical wire. The X-10 protocol is
typically used in simple control scenarios like the remote or automatic
turning on/off of lights or appliances.
XDSL
An acronym denoting the use of “any” DSL, without making reference to
specific implementations of DSL, such as ADSL.
XML (Extensible Markup Language)
A specification developed by the W3C. XML is a pared-down version of
SGML, designed especially for Web documents. It allows designers to
create their own customized tags, enabling the definition, transmission,
validation, and interpretation of data between applications and between
organizations. Whether XML eventually supplants HTML as the standard Web
formatting specification depends a lot on whether it is supported by
future Web browsers. Microsoft Internet Explorer version 5 handles XML,
but renders it as CSS, and Mozilla (Netscape) is still experimenting
with XML support.
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