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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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