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| "Technology Services for Multi-Family Housing" | |
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| | | GLOSSARY OF TERMS Access Point: A wireless LAN transceiver that acts as a center point and bridges between wireless and wired networks. Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA): LAN media access method as specified by the IEEE 80-2.11 specification. Direct Sequence Spread Spectrum (DSSS): A type of spread spectrum radio transmission that spreads its signal continuously over a wide frequency band. Diversity Antennas: An intelligent system of two antennas that continually senses incoming radio signals and automatically selects the antenna best positioned to receive it. 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. Multi-path: The echoes created as a radio signal bounces off of physical objects. 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. Roaming: A feature of some access points that allow users to move through a facility while maintaining unbroken connection to the LAN. 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. 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. 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. Gain: A method of increasing the transmission distance of a radio by the concentration of 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. Therefor, as gain increases, the decrease in angle of coverage is inversely proportional. 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). Omni-Directional Antenna: An antenna that provides a 360 degree transmission pattern. These type of antennas are used when coverage in all directions is required. | | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
