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chapter8 H

vocabulary terms

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
Created by: cgeaski