A core network transmission technique that involves splitting
information into "packets" of data that are then re-routed independently through the network
over different routes to the final destination. This technique is attractive for mobile access because
the radio spectrum is used only when data is actually being transmitted. The
alternative is circuit switching. GPRS is a packet-based technology designed for
digital mobile networks.
Personal Communication Network. PCNs are usually short range (100's of feet to 1 mile
or so) and involve cellular radio type architecture. Services include digital voice, FAX,
mobile data and national/international data communications. Also -- A network of pocket-size
radio telephones served by clusters of receiver transmitter cells.
Personal Communications Service. A generic term for a mass-market mobile
personal communications service, independent of the technology used to provide it. Also, a type
of digital wireless network in North America that operates in the 1,900 MHz frequency band.
Example: Sprint PCS, which uses CDMA technology.
This is a catch-all term for an integrated circuit that can be programmed
to perform complex functions. A PLD consists of arrays of AND and OR gates. A system designer implements
a logic design with a device programmer that blows fuses on the PLD to control gate operation.
System designers can use development software that converts basic code into instructions a
device programmer needs to implement a design. PLDs types can classified as --
(1) PROMs (Programmable Read Only Memory), which offer high speed and low cost for relatively small designs;
(2) PLAs (Programmable Logic Array), which offer flexible features for more complex designs; or (3)
PAL/GALs (Programmable Array Logic/Generic Array Logic), which offer good flexibility and are faster
and less expensive than PLAs.
A European R&D initiative that started in the 1980s. It was the starting point
for some of the radio developments that are being employed today in mobile
third generation systems.
Also see Cell. The area served by a radio base station in a cellular
or cordless communication system. This is where the term "cellular" came from. Cell size
ranges from a few tens of metres to several kilometres.
A communication service (usually two-way) in which
the information sent is received instantly by the other party in a continuous stream.
As an example, telephone calls and videoconferencing are real-time, while database access
and e-mails are not.
A telephone system where subscribers are connected to the Public Switched Telephone
Network using radio signals rather than copper wire for part or all of the connection between
the subscriber and the switch. Includes cordless access systems, proprietary fixed radio
access and fixed cellular systems. Synonymous with Fixed Radio Access and Wireless Local Loop
Systems.
In an antenna, a parasitic element located in a direction other than forward of the
driven element intended to increase the direcctivity of the antenna in the forward
direction.
Ability of a cordless or mobile phone user to travel from one cell to
another, with complete communications continuity. Supported by a cellular network
of radio base stations. Roaming is also the term given for inter-network operability,
i.e. moving from one network provider to another (internationally).
An industrial measurement and control system consisting of a central host or
master (usually called a master station, master terminal unit or
MTU); one or more field data gathering and control units or remotes
(usually called remote stations, remote terminal units, or RTU's);
and a collection of standard and/or custom software used to monitor
and control remotely located field data elements. Contemporary SCADA
systems exhibit predominantly open-loop control characteristics
and utilize predominantly long distance communications, although
some elements of closed-loop control and/or short distance
communications may also be present. Similar to Distributed Control Systems,
but usually the field elements are more geographically dispersed.
Operating method in which transmission is made possible alternatively in
one direction of a telecommunications channel, for example, by means of manual
control.
A communication technique that spreads a signal bandwidth over a wide range of frequencies
for transmission and then de-spreads it to the original data bandwidth at the receiver.
A joint venture originally set up by Ericsson, Nokia and Psion to develop
an industry-standard operating system for mobile multimedia terminals (EPOC).
Two-way communications in which equal volumes of information flow in each direction.
For example, a videoconference call is symmetrical, Video-on-Demand is not. Also see
asymmetric communications.
A digital multiplexing (channel sharing) technique whereby each signal is sent at a
repeating time slot in a frequency channel. Because the data from each user always appears in
the same time slot, the receiver can separate the signals. A technique used in
Second Generation wireless phone systems, such as GSM, D-AMPS
(IS-136) and PDC air interfaces. D-AMPS in North America is often called just TDMA -- see
TDMA (ANSI-136) below.
"TDMA" has been adopted as the new name for the "Digital
AMPS" (D-AMPS) mobile standard, now called ANSI-136, used in the Americas,
Asian Pacific and other areas. TDMA services can be delivered in the 800 MHz and
1900 MHz frequency bands.
A location identification technology that uses the time delay between arrival of
signals received by at least three different antennas, and knowing the transmit and
receive time, can determine position.
Revamped broadband digital networks expected in the early 2000s, that will be able
to handle broadband data communications, with transmission rates much higher than the
current average of 10 Kbs per second.
Universal Mobile Telecommunications System. The European
third-generation system developed under the auspices of ETSI - A third generation
and highly advanced system optimized for GSM operators.
Universal Wireless Communications consortium. The industry body that
represents the interests of vendors, operators and users of AMPS and TDMA
(ANSI-136) mobile networks
A classification of the information capacity (or bandwidth) of a
communication channel. Wideband is generally taken to mean a bandwidth
between 64 kbps and 2 Mbps.
A refinement of CDMA technology that could raise data transmission rates up to two
megabits per second. W-CDMA spreads the chips of the wireless signal over a much wider
band of frequencies than CDMA does. This is the air interface technology selected by the major
Japanese mobile communications operators, and in January 1998 by ETSI, for
wideband wireless access to support third-generation services. This technology will permit
very high-speed multimedia services such as full-motion video,
Internet access and video-conferencing.
A telephone system where subscribers are connected to the Public Switched Telephone
Network using radio signals rather than copper wire for part or all of the connection between
the subscriber and the switch. Includes cordless access systems, proprietary fixed radio
access and fixed cellular systems. Synonymous with Fixed Radio Access and Radio in the Loop
Systems.
A collection of wireless MANs or WANs that link together an entire nation or the world.
UANs typically use very small aperture (VSAT) earth station gateway technology.
A multiple element parasitic antenna; originated by Yagi-Uda, in Japan; a common VHF
and UHF means of achieving high antenna gain in a compact physical size. It is a linear
end-fire array consisting of a driven element, a reflector element, and one or more
director elements.
Low power, Low Rate Wireless Personal Area Networking (LR-WPAN) technology
designed for wireless automation and other lower data tasks, such as smart home
automation and remote monitoring. Advantages: Low power consumption, reliable,
relative cheap equipment costs. Disadvantages: Low bandwidth (usually under 250 Kbps)
may limit the number of applications.
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