Glossary
Access point
A transceiver used to connect one or more stand alone clients to a wired network.
BER
Short for Bit Error Rate, used for measuring the quality of a connection and as a reference for performance specifications such as the receive sensitivity where the receiver sensitivity is quoted as dBm @BER 10E-5 ie 1 bit wrong out of 100,000. This is considered to be the highest error rate than can be recovered from by higher level protocols.
Bridge (Wireless)
A transceiver used to link two wired networks together. One transceiver is required for each end of the link.
BSS
A basic service set (BSS) is the smallest unit of an 802.11 network. A BSS is simply a collection of devices that can communicate by sending 802.11 packets to each other. A group of these basic service sets is called an ESS, or extended service set which is identified by its SSID or service set identifier.
dBm
A measure of power output. It is the power referenced to a signal of 1mW. Decibels are logarithmic scale and an increase of 3dB is twice the power so 3dBm=2mW, 6dBm=4mW, 9dBm=8mW and so on. see Useful tools.
Donk
The sound a piece of equipment makes when you throw it off the roof after it has locked up for the third time.
DSSS
Short for Direct Sequence Spread Spectrum. DSSS is a transmission technology where a data signal at the sending station is combined with a 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. Most systems available now use DHSS.
Fade Margin
Normally an extra 10dB is allowed for above the amount required for the link to work. This is to allow for unforeseen effects. The additional fade can be due to changes in ground reflectivity due to changes in atmospheric conditions or non constant multipath interference.
FHSS
Short for Frequency-Hopping Spread Spectrum. FHSS is where the data signal is modulated with a narrow carrier signal that "hops" in a random but predictable sequence from frequency to frequency. FHSS is less widely used but can have some advantages in areas of high interference or reflections.
Fresnel Zone
An area around the direct line between the two ends of the link that should be kept clear. See the Radio Link page.
Gateway
A device which passes data through destined for devices that are not on the same network as the sender.
MAC Address
This is short for Media Access Control Address. It is a unique identifier for every networking interface. See Standards, Access Points and Cards.
Omnidirectional
Normally a stick-like aerial that provides 360 degree coverage. see Aerials, connectors and cable.
Path Loss
The loss in signal that is encountered between the two ends of the link see The Radio Link.
Pigtail
An adapter between two types of connectors joined by a short length of cable. See Aerials, Connectors and Cable.
POE
Short for Power Over Ethernet. A system where the unused pairs of a network cable are used to remotely feed power to a device. This is used to avoid running power supply cables to equipment.
Polarisation
The orientation of the radio signal from an aerial. Both ends of a link should use the same polarisation. See Aerials, Connectors and Cables.
Receiver sensitivity.
The lowest level of signal that can be used for a given rate of errors. Dependant on speed of link. See Standards, Access Points and Cards.
Roaming
The ability to move from one access point coverage area to another without interruption in service or loss in connectivity.
SSID
This stands for Service Set IDentifier. It is a code that identifies the network. See BSS above.
WEP
Short for Wired Equivalency Privacy. It is a form of encryption that was intended to provide the same level of security as that found on a normal wired LAN. See Standards, Access Points and Cards.
Wi-Fi
Wi-Fi Certified equipment has been tested by the Wi-Fi alliance. An organization made up of wireless equipment providers who certify 802.11 based products for interoperability.
Whilst all 802.11a/b/g products are called Wi-Fi, only products that have passed the Wi-Fi Alliance testing are allowed to refer to their products as "Wi-Fi Certified" (a registered trademark).
Yagi
A directional aerial similar to a TV aerial. See Aerials, Connectors and cCable
