Term
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Definition
After a L3 intercontroller roam, the client is associated to a new 'foreign' WLC. The client retains connectivity to its original VLAN and subnet. |
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Term
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Definition
Degradation of an RF signal as it travels through free space |
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Term
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Definition
The number of times a signal makes one complete up and down cycle in 1 second. |
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Term
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Definition
Frequency Hopping Spread spectrum |
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Term
Describe FHSS and which 802.11 version requires it |
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Definition
802.11n When a transmitter hops between frequencies all across a band |
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Term
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Definition
The elliptical space between a transmitter and receiver that must be kept clear of objects. Otherwise the RF signal will be degraded. |
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Term
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Definition
How effectively an antenna can focus RF energy in a certain direction |
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Term
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Definition
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Term
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Definition
The time required between OFDM symbols to prevent intersymbol interference. |
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Term
Length of guard interval in 802.11n |
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Definition
In 802.11n the GI can reduced from 800 ns to 400 ns. |
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Term
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Definition
one cylce per second when measuring a frequency |
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Term
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Definition
802.11n used to scale performance to a maximum of 600 Mbps |
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Term
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Definition
The azimuth plane. Shows a top-down view of the radiation pattern |
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Term
What is a in phase signal |
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Definition
When the cycles of two identical signals are in sync with each other |
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Term
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Definition
Independent basic service set - the term for a Ad hoc network |
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Term
Independent basic service set (IBSS) |
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Definition
A impromptu wireless network created without an AP or a BSS.(AKA Ad hoc network) |
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Term
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Definition
When a AP provids a BSS for wireless clients |
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Term
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Definition
Client roaming between APs that are joined to two different controllers |
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Term
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Definition
The amount of time required by standards to separate adjacent frames on a channel |
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Term
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Definition
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Term
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Definition
Data corruption caused by OFDM symbols arriving too close together at a receiver. |
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Term
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Definition
Usually caused by signals that take different paths from transmitter to receiver. E.x. lag time between scattered signles reaching recever |
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Term
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Definition
Client roaming that occurs between two APs joined to the SAME controller (Intra-controller) |
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Term
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Definition
Cisco software which finds an autonomous APs IP address and can set its IP address and SSID |
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Term
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Definition
An ideal, theoretical antenna that radiates RF equally in every direction. (does not exist in reality) |
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Term
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Definition
An intercontroller roam where the WLANs of the two controllers are configured for the same Layer 2 VLAN ID; also known as a local-to-local roam. |
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Term
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Definition
An intercontroller roam where the WLANs of the two controllers are configured for different VLAN IDs; also known as a local-to-foreign roam. To support the roaming client, a tunnel is built between the controllers so that client data can pass between the client?s current controller and its original controller. |
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Term
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Definition
A legacy Cisco proprietary wireless security method |
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Term
Link aggregation group (LAG) |
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Definition
A grouping or bundling of multiple physical links into a single logical link |
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Term
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Definition
The cumulative sum of gains and losses measured in dB over the complete RF signal path; a transmitter?s power level must overcome the link budget so that the signal can reach a receiver effectively |
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Term
Management frame protection (MFP) |
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Definition
A method developed by Cisco to protect wireless clients and APs from attacks involving spoofed management frames |
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Term
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Definition
A logical link that is used for normal management traffic. If an AP-manager interface is not configured, the management interface also terminates CAPWAP tunnels from APs. |
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Term
Maximal-ratio combining (MRC) |
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Definition
An 802.11n technique that takes multiple copies of a signal, received over multiple antennas, and combines them to reconstruct the original signal. |
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Term
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Definition
A network of APs used to cover a large area without the need for wired Ethernet cabling; client traffic is bridged from AP to AP over a backhaul network |
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Term
Message integrity check (MIC) |
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Definition
A cryptographic value computed from the contents of a data frame and used to detect tampering. |
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Term
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Definition
A wireless LAN controller that acts as the anchor or home base for remote wireless clients that are joined to a different controller |
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Term
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Definition
A logical grouping of controllers that facilitates efficient client roaming and mobility |
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Term
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Definition
The transmitter?s process of altering the carrier signal according to some other information source |
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Term
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Definition
A very short omnidirectional antenna composed of a single wire segment set over a metal ground plane |
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Term
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Definition
Reflected copies of an RF signal arrive at a receiver after taking different paths through free space |
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Term
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Definition
High availability offered by N number of active controllers plus one idle standby controller. |
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Term
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Definition
High availability offered by N number of active controllers. The AP load is distributed across the active controllers, so no additional backup controller is used. |
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Term
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Definition
High availability offered by N number of active controllers plus one idle standby controller. |
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Term
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Definition
RF signals that use a very narrow range of frequencies |
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Term
Neighboring channel interference |
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Definition
RF signal interference caused by two or more transmitters using channels that are different, but do not completely overlap |
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Term
Network allocation vector (NAV) |
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Definition
An internal timer maintained by each wireless device that measures the number of timeslots before a transmission may be attempted |
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Term
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Definition
Signals or RF energy that do not come from 802.11 sources |
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Term
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Definition
The average power level of noise measured at a specific frequency |
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Term
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Definition
A type of antenna that propagates an RF signal in a broad range of directions in order to cover a large area |
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Term
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Definition
An 802.11 authentication method that requires clients to associate with an AP without providing any credentials at all |
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Term
Open system authentication |
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Definition
A simple method used to verify that a wireless device uses 802.11 before it is permitted to join a BSS |
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Term
Orthogonal frequency-division multiplexing (OFDM) |
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Definition
A data transmission method that sends data bits in parallel over multiple frequencies within a single 20 MHz wide channel. Each frequency represents a single subcarrier. |
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Term
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Definition
The condition when the cycles of one signal are shifted in time in relation to another signal |
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Term
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Definition
A highly directional antenna that uses a passive dish shaped like a parabola to focus an RF signal into a tight beam |
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Term
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Definition
A method used to scan for available APs by listening to their beacon frames |
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Term
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Definition
A directional antenna that has a planar surface and is usually mounted on a wall or column |
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Term
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Definition
Pre-shared key authentication as applied to WPA or WPA2 |
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Term
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Definition
A measure of shift in time relative to the start of a cycle; ranges between 0 and 360 degrees |
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Term
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Definition
To determine whether a channel is available, a device simply listens to any signals that might be present. |
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Term
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Definition
An AP configured to bridge a wired network to a companion bridge at the far end of a line of sight path |
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Term
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Definition
A round graph that is divided into 360 degrees around an antenna and into concentric circles that represent decreasing dB values. The antenna is always placed at the center of the plot. |
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Term
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Definition
The orientation (horizontal, vertical, circular, and so on) of a propagating wave with respect to the ground |
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Term
Primed controller address |
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Definition
The name or IP address of a controller that is configured in advance on an AP |
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Term
Protected access credential (PAC) |
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Definition
Special-purpose data that is used as an authentication credential in EAP-FAST |
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Term
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Definition
An authentication method that uses a certificate on the AS for outer authentication and a TLS tunnel for inner authentication. Clients can provide their credentials through either MS-CHAPv2 or GTC. |
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Term
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Definition
Method of supporting backward compatibility between an advanced and a legacy wireless standard, such as 802.11g and 802.11b, respectively. For example, each 802.11g OFDM transmission is flagged with RTS/CTS messages sent in the lower-rate DSSS format. |
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Term
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Definition
A virtual MAC address that a controller assigns to each uniquely identified non-802.11 interferer so that it can be reported and displayed. See also cluster ID. |
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Term
Public Key Infrastructure (PKI) |
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Definition
An enterprise-wide system that generates and revokes digital certificates for client authentication |
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Term
Quadrature amplitude modulation (QAM) |
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Definition
A modulation method that combines QPSK phase shifting with multiple amplitude levels to produce a greater number of unique changes to the carrier signal. |
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Term
What does the number infront of the QAM do |
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Definition
Designates how many carrier signal changes are possible |
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Term
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Definition
A plot that shows the relative signal strength in dBm at every angle around an antenna |
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Term
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Definition
The portion of the frequency spectrum between 3 kHz and 300 GHz |
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Term
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Definition
An authentication server used with 802.1x to authenticate wireless clients |
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Term
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Definition
The process by which a wireless client changes its association from one BSS to another as it moves |
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Term
Received signal strength indicator (RSSI) |
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Definition
The measure of signal strength (in dBm) as seen by the receiver. RSSI is normally negative (0 to ?100) because the received signal is always a degraded form of the original signal that was sent. |
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Term
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Definition
The effect of an RF signal meeting a dense, reflective material, such that it is sent in a different direction |
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Term
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Definition
The effect of an RF signal meeting the boundary between two different materials, causing its trajectory to change slightly |
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Term
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Definition
A device that repeats or retransmits signals it receives, effectively expanding the wireless coverage area |
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Term
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Definition
A wireless AP that operates outside local administrative control |
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Term
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Definition
A controller that is elected to handle all of the RRM algorithms for the entire RF group |
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Term
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Definition
A logical grouping of wireless LAN controllers that operates as a single RF domain. RRM algorithms run on a per-RF group basis. |
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Term
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Definition
A controller that is elected to handle all of the RRM algorithms for the entire RF group |
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Term
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Definition
The process a wireless client uses to move from one AP to another as it changes location |
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Term
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Definition
The RSSI threshold (in dBm) that divides unintelligible RF signals from useful ones |
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Term
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Definition
A physical nontrunking interface that connects a wireless controller to a switched network and carries only out-of-band management traffic |
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Term
Service set identifier (SSID) |
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Definition
A method used to authenticate a wireless device with a BSS by using a shared WEP key |
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Term
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Definition
Radio Resource Management; a set of algorithms that are used to maintain a stable and optimum wireless network even in a changing RF environment |
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Term
Shared key authentication |
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Definition
A method used to authenticate a wireless device with a BSS by using a shared WEP key |
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Term
Signal-to-noise ratio (SNR) |
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Definition
A measure of received signal quality, calculated as the difference between the signals?s RSSI and the noise floor. A higher SNR is preferred. |
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Term
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Definition
Distributing streams of data across multiple radio chains with spatial diversity |
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Term
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Definition
An independent stream of data that is sent over a radio chain through free space. One spatial stream is separate from others due to the unique path it travels through space. |
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Term
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Definition
A device that sweeps through a range of frequencies and displays signals that it receives. The signal data can be processed and displayed in a variety of ways to assist in the analysis. |
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Term
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Definition
RF signals that spread the information being sent over a wide range of frequencies |
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Term
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Definition
An 802.11 client device that is associated with a BSS |
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Term
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Definition
An 802.1x entity that exists as software on a client device and serves to request network access |
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Term
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Definition
An 802.11 data rate that can be supported by a client when it associates with an AP |
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Term
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Definition
A complete group of encoded chips that represent a data bit |
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Term
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Definition
Temporal Key Integrity Protocol |
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Term
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Definition
A wireless security scheme developed before 802.11i that provides a MIC for data integrity |
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Term
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Definition
Transmit power control; an RRM algorithm that adjusts the transmit power level of Aps to minimize cell overlap and interference |
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Term
Traffic indication map (TIM) |
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Definition
A list of the association IDs of wireless clients who are in a power save mode but have frames buffered. The TIM is included in beacon frames sent by an AP. |
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Term
Transmit beamforming (TxBF) |
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Definition
An 802.11n method to transmit a signal over multiple antennas, each having the signal phase carefully crafted, so that the multiple copies are all in phase at a targeted receiver |
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Term
Unscheduled automatic power save deliver (U-APSD) |
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Definition
The method defined in 802.11e and WMM that allows a wireless client to enter power save mode and then have buffered frames delivered whenever the client is ready to receive them |
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Term
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Definition
The method by which a wireless device calculates that a channel is available, based on frame duration information that is used to set the NAV |
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Term
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Definition
A logical link used to support wireless clients with things like DHCP relay and web authentication |
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Term
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Definition
The physical distance that a wave travels over one complete cycle |
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Term
Wi-Fi Protected Access (WPA) |
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Definition
A Wi-Fi Alliance standard that requires pre-shared key or 802.1x authentication, TKIP, and dynamic encryption key management; based on portions of 802.11i before its ratification |
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