Question | Answer |
802.11a | wireless networking technique that uses multiple frequencies in the 5-GHz frequency range |
802.11a | used with higher frequencies,unique method of encoding data and more available bandwith |
802.11b | wireless technique that uses direct sequence spread spectrum signaling in the 2.4-2.4835 GHz frequency range |
802.11b | separates the 2.4 GHZ band into 14 overlapping 22-MHz chanels |
802.11g | wireless networking technique designed to be compatible with 802.11b while using different encoding techniques |
802.11n | wireless networking technique that may issue signals in the 2.4 or 5 GHx band and can acheive throughput between 65 and 600 Mbps. |
802.11n | backward compatible with 802.11a,b and g.accomplishes this thru MIMO,channel bonding and frame aggregation |
802.16 | standard for wireless MANs.use frequencies between 2 and 66 GHz.antenna operate in line of sight and out of line of sight and covers 30 miles. |
802.16e | most popular version of WiMax |
802.16e | IEEE improved the mobility and QoS characteristics of the technology,better suited to VoIP and mobile phone uers |
access point | a device used on wireless LANs that transmits and receives wireless signals to and from multiple nodes and retransmits them to the rest of the network segment |
access point | can connect a group of nodes with a network or two networks with each other.use directional or omnidirectional antennas |
active scanning | method used by wireless stations to detect the presence of an access point |
active scanning | station issues a probe to each channel in its frequency range and waits for the access point to respon |
ad hoc | a type of wireless LAN |
ad hoc | stations communicate directly with each other rather then using an access point |
association | the communication that occurs between a station and an access point to enable the station to connect tot he network via the access point |
beacon frame | a frame issued by an access point to alert other nodes of its existence |
bluetooth | wireless networking standard that uses frequency hopping spread spectrum signaling in the 2.4GHz band |
bluetooth | designed primarily for use with small office,home networks in which multiple devices are connected |
basic service set | a group of stations that share an access point |
basic service set identifier | the identifier for a basic service set |
channel bonding | recommended for use in the 5 GHz range because this band has more available channels and suffers less interference than the 2.4 GHz band |
channel bonding | combination of two 20-MHz frequency band to create one 40-MHz frequency band to carry more then twice the amount of data that a single 20-MHz band could. |
carrier sense multiple access with collision avoidance | a network access method used on 802.11 wireless networks |
csma/ca | before a node begins to send data it checks the medium.if it detects no activity it waits a bit more then sends the data |
csma/ca | if node detects activity on the network,it waits a while,checks he channel again for no activity.this helps to minimize the chance of a collision |
dial return | a method of satellite internet access |
dial return | a subscriber receives data via a satellite downlink transmission,but sends data to the satellite via a modem,dial-up,connection |
diffraction | occurs when an electromagnetic wave encounters an obstruction and splits into secondary waves.secondarfy waves continue to propagate in the direction they were split |
diffraction | wireless signals would look like they are being bended around the obstacle |
directional antenna | issues wireless signals along a single direction or path |
downlink | a connection from an orbiting satellite to an earth based receiver |
direct sequence spread spectrum | a transmission technique |
dsss | a signals bits are distributed over an entire frequency band at once.each bit is encoded so that the receiver can reassemble the original sinal upon receiving the bits |
extended service set | a groupr of access points and associated station,or basic service sets,connected to the same LAN |
extended service set identifier | a special identifier shared by basic service set that belongs to the same extended service set |
fading | change in a wireless signals strength as a result of some of the electromagnetic energy being scattered,reflected, or diffracted after being issued by the transmitter |
frequency hopping spread spectrum | a wireless signaling technique |
fhss | a signal jumps between several different frequencies within a band in a synchronization pattern known as a channels receiver and transmitter |
fixed | a type of wireless system in which the locations of the transmitter and receiver are static |
fixed | in a fixed connection the transmitting antenna focuses its energy directly toward the receiving antenna,point to point link. |
geosynchronous orbit | a satellite that maintains a constant distance from a point on the equator at every point in its orbit |
hot spot | an area covered by a wireless access point that provides visitors with wireless services |
infrastructure WLAN | station communicates with an access point and not directly with each other |
iwconfig | a command line utility for viewing and setting wireless interface parameters on LINUX and UNIX workstation |
low earth orbiting | satellite that orbits the Earth with an altitude between 100 and 900 miles.cover a smaller geographical range than geo satellites and require less power |
line of sight | a wireless signal that travels directly in a straight line from its transmitter to its intended receiver.uses the least amount of energy and has the clearest signal |
medium earth orbiting | satellite that orbits the earth roughyly 6000 to 12000 miles above its surface |
meo | satellites cover larger areas while using less power and less signal delay than geo satellites |
multiple input multiple output | the ability for access points to issue multiple signals to stations,thereby multiplying the signals strength and increasing their range and data carrying range capacity |
mobile | wireless system in which the receiver can be located anywhere within the transmitters range.allows the receiver to roam from one place to another while continuong to pick up the signal |
multipath | the characteristic of wireless signals that follow a number of different paths to their destination |
narrowband | a type of wireless transmission in which signals travel over a single frequency or within a specified frequency range |
omnidirectionsl antenna | antenna that issues and receives wireless signals with equal strength and clarity in all directions |
omnidirectional antenna | used when many different receivers must be able to pick up the signal |
personal area network | a small home,network composed of personal communication devices |
passive scanning | the process in which a station listens to several channels within a frequency range for a beacon issued by an access point |
probe | a type of frame issued by a station during active scanning to find nearby access points |
radiation pattern | the relative strength over a three dimensional area of all the electromagnetic energy an antenna sends or receives |
range | the area in which signals issued from an antenna or wireless sytem can be consistently and accurrately received |
reassociation | the process of a station establishing a connection with a different access point. |
reflection | occurs when an electromagnetic wave encounters an obstacle and bounces back towards its source |
reflection | a wireless signal will bounce off objects whose dimensions are latge compared to the signals average wavelength |
roaming | the process that describers a station moving between bss without losing connectivity |
request to send clear to send | an exchange in which wireless station requests the exclusive rights to communicate with an access point and the access point confirms that it has granted the request |
satellite return | a type of satellite internet access in which a subscriber sends and receives data to and from the internet over the satellite link. |
satellite return | symmetrical technology in which both upstream and downstream throughputs is higher |
scanning | the process a wireless station undergoes to find an access point |
scattering | the diffussion of a wireless signal that results from hitting an object that has smaller dimensions compared to the signals wavelength. |
scattering | related to the roughness of the surface a wireless signal encounters |
site survey | an assessment of client requirements,facility characteristics,and coverage areas to determine an access point arrangement that will ensure relilable wireless connectivity in a given area |
spread spectrum | a type of wireless transmission in which lowered level signals are distributed over several frequencies simultaneously.more secure then narrowband |
service set identifier | a unique character string used to identify an access point on an 802.11 network |
station | an end node on a network |
transponder | the equipment on a satellite that recives an uplinked signal from earth,amplifies the signal,modifies its frequency,then retransmits it in a downlink, to an antenna on earth |
uplink | a connection from an earth based transmitter to an orbiting satellite |
wireless | the signals made of electromagnetic energy that travels thru the atmosphere |
wireless broadband | term used to describe the recently released standards for higher throughput,long distance digital data exchange over wireless connections. |
wireless gateway | an access point that provides routing functions and is used as a gateway |
wireless router | an access point that provides routing functions |
wireless spectrum | a continuum of electromagnetic waves used for data and voice communications.waves are arranged from lowest to highest frequencies. |
wireless LAN | a LAN that uses wireless connections for some or all of its transmissions |