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Warning:You
are entering a "techie" zone. There is no need to
understand these technical terms in order to use our
wireless service. They are just here for the curious.
802.11:
The IEEE standard that specifies a carrier sense media
access control and physical layer specifications for 1 and 2
megabit per second wireless LANs.
802.11b:
The IEEE standard that specifies a carrier sense media
access control and physical layer specifications for 5.5 and
11 megabit per second wireless LANs.
802.3:
The IEEE standard that specifies carrier sense media access
control and physical layer specifications for Ethernet LANs.
Access Point:
A wireless LAN transceiver that acts as a center point and
bridges between wireless and wired networks.
Ad Hoc Network:
A wireless network composed only of stations without access
points.
Bandwidth:
Specifies the amount of the frequency spectrum that is
usable for data transfer. It identifies the maximum data
rate that a signal can attain on the medium without
encountering significant loss of power.
Beamwidth:
The angle of signal coverage provided by a radio. Beamwidth
may by decreased by a directional antenna to increase gain.
Boot Protocol (BOOTP):
The protocol used for the static assignment of IP addresses
to devices on the network.
Bridge:
A device used to connect LANs by forwarding packets across
connections at the Media Access Control (MAC) layer.
Carrier Sense Multiple
Access with Collision Avoidance (CSMA/CA):
Wireless LAN media access method as specified by the IEEE
802.11 specification.
Carrier Sense Multiple
Access with Collision Detection (CSMA/CD):
Ethernet media access method as specified by the IEEE 802.3
specification.
Complementary Code Keying
CCK):
Modulation technique used by IEEE 802.11-compliant wireless
LANs for transmission at 5.5 and 11Mbps.
dBi:
A ratio of decibels to an isotropic antenna that is commonly
used to measure antenna gain. The greater the dBi value, the
higher the gain and, as such, the more acute the angle of
coverage.
Differential Binary Phase
Shift Keying (DBPSK):
Modulation technique used by IEEE 802.11-compliant wireless
LANs for transmission at 1Mbps.
Differential Quadrature
Phase Shift Keying (DQPSK):
Modulation technique used by IEEE 802.11-compliant wireless
LANs for transmission at 2Mbps.
Dipole:
A type of low gain (2.2 dBi) antenna consisting of two
(often internal) elements.
Direct Sequence Spread
Spectrum (DSSS):
A type of spread spectrum radio transmission that spreads
its signal continuously over a wide frequency band.
Directional Antenna:
An antenna that concentrates transmission power into a
direction thereby increasing coverage distance at the
expense of coverage angle. Directional antenna types include
yagi, patch and parabolic dish.
Diversity Antennas:
An intelligent system of two antennas that continually
senses incoming radio signals and automatically selects the
antenna best positioned to receive it.
Dynamic Host Configuration
Protocol (DHCP):
A protocol available with many operating systems that
automatically issues IP addresses within a specified range
to devices on a network. The device retains the assigned
address for a specific administrator-defined period.
Ethernet:
The predominant wired LAN technology standardized in the
IEEE 802.3 specification.
Frequency Hopping Spread
Spectrum (FHSS):
A type of spread spectrum radio transmission in which the
transmitter and receiver hop in synchronization from one
frequency to another according to a prearranged pattern.
Fresnel Effect:
A phenomenon related to line of sight whereby an object that
does not obstruct the visual line of sight obstructs the
line of transmission for radio frequencies.
Gain:
A method of increasing the transmission distance of a radio
by the concentration its signal in a single direction,
typically through the use of a directional antenna. Gain
does not increase a radio's signal strength, but simply
redirects it. Therefore, as gain increases, the decrease in
angle of coverage is inversely proportional.
Gigahertz (GHz):
One billion cycles per second. A unit of measure for
frequency.
Hertz (Hz):
Cycles per second. A unit of measure for frequency.
Hidden Node:
A station on a wireless LAN that attempts to transmit data
to another station but, due to its location relative to the
others, cannot sense that there is a third station
simultaneously communicating with the intended recipient.
Lost message and multiple retries is the result.
Institute of Electrical and
Electronic Engineers (IEEE):
A professional society serving electrical engineers through
its publications, conferences, and standards development
activities. The body responsible for the Ethernet 802.3 and
wireless LAN 802.11 specifications.
Isotropic:
An antenna (or a theoretic construct of an antenna) that
radiates its signal 360 degrees both vertically and
horizontally-- a perfect sphere.
Line of Sight:
An unobstructed straight line between two transmitting
devices. Line of sight is typically required for long-range
directional radio transmission. Due to the curvature of the
earth, the line of sight for devices not mounted on towers
is limited to 16 miles (26km).
Management Information Base
(MIB):
A collection of network operational information residing in
a virtual store that may be accessed, typically through an
SNMP-compliant system, for analysis.
Media Access Control (MAC)
Layer:
Provides media access services for IEEE 802 local area
networks.
Megahertz (MHz):
One million cycles per second. A unit of measure for
frequency.
Modulation:
Any of several techniques for combining user information
with a transmitter's carrier signal.
Multipath:
The echoes created as a radio signal bounces off of physical
objects.
Omni-Directional Antenna:
An antenna that provides a 360 degree transmission pattern.
These types of antennas are used when coverage in all
directions is required.
Packet:
A basic message unit for communication across a network. A
packet usually includes routing information, data, and
(sometimes) error detection information.
Parabolic:
A concave or dish-shaped object. Often refers to dish
antennas.
Peer-to-Peer Network:
A network design in which each computer shares and uses
devices on an equal basis.
Physical Layer (PHY):
Provides for the transmission of data through a
communications channel by defining the electrical,
mechanical and procedural specifications for IEEE 802 local
area networks.
Protocol:
Rules for communicating, particularly for the format and
transmission of data.
Radio Frequency (RF):
A generic term for radio-based technology.
Range:
A linear measure of the distance that a transmitter can send
a signal.
Receiver Sensitivity:
A measurement of the weakest signal a receiver can receive
and still correctly translate it into data.
Reverse Polarity
TNC(RP-TNC):
A connector type unique to Aironet radios and antennas. Part
15.203 of the FCC rules covering spread-spectrum devices
limits the types of antennas that may be used with
transmission equipment. In compliance with this rule,
Aironet, like all other wireless LAN providers, equips its
radios and antennas with a unique connector to prevent
attachment of non-approved antennas to radios.
Roaming:
A feature of some access points that allow users to move
through a facility while maintaining unbroken connection to
the LAN.
Simple Network Management
Protocol (SNMP):
The network management protocol that defines the transfer of
LAN operational data between Management Information Bases
(MIBs).
Spread Spectrum:
A radio transmission technology that "spreads" the user
information over a much wider bandwidth than otherwise
required in order to gain benefits such as improved
interference tolerance and unlicensed operation.
Wired Equivalent
Privacy(WEP):
Optional security mechanism defined within the 802.11
standard designed to make the link integrity of the wireless
medium equal to that of a cable.
Yagi:
A type of often cylindrical directional antennas.
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