Term
|
Definition
|
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Term
|
Definition
| Doubling the distance between a transmitter and receiver will decrease the received signal by 6 dB. Halving the distance between a transmitter and receiver will increase the received signal by 6 dB |
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Term
|
Definition
| A level of desired signal above what is required |
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Term
|
Definition
| Provides two functions in a communication system. When connected to the transmitter, it collects the AC signal that it receives from the trasmitter and directs, or radiates, the RF waves away from the antenna in a pattern specific to the antenna type. When connected to the receiver, it takes the RF waves that it receives through the air and directs the AC signal to the receiver |
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Term
|
Definition
| Provides approximate values when performing RF math calculations. 4 rules |
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Term
|
Definition
| It is a measurement of the ratio between two powers. Equals 10 * log10(P1/P2) |
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Term
| system operating margin (SOM) |
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Definition
| The calculation of the amount of RF signal that is received minus the amount of signal required by the receiver |
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Term
|
Definition
| The calculation of the amount of RF signal that is received minus the amount of signal required by the receiver |
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Term
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Definition
| A point that radiates signal equally in all directions. e.g. sun |
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Term
|
Definition
| The amount of signal a wireless station must receive in order to distinguish between data and noise |
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Term
| equivalent isotropically radiated power (EIRP) |
|
Definition
| The highest RF signal strength that is transmitted from a particular antenna |
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Term
|
Definition
| A unit of power equal to 1/1000 of a watt |
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Term
|
Definition
| The final component in a wireless medium. It takes the carrier signal that is received from the antenna and translates the modulated signals into 1s and 0s. it then takes this data and passes it to the computer to be processed |
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Term
|
Definition
| A basic unit of power. Equal to 1 ampere (amp) of current flowing at 1 volt |
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Term
| received signal strength indicator (RSSI) |
|
Definition
| Used by a wireless device to determine if another device is transmitting, also known as a clear channel assessment. An optional 802.11 parameter with a value of 0 to 255. It is designed by the hardware manufacturer as a relative measurement of the RF power that is received. |
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Term
| intentional radiator (IR) |
|
Definition
| A device that intentionally generates and emits radio frequency energy by radiation or induction |
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Term
|
Definition
| Units of measure that provide absolute measurement values, not relative or comparative measurements. Watt is an example |
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Term
|
Definition
| A point source that radiates signal equally in all directions. e.g. sun |
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Term
| Newton's Inverse Square Law |
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Definition
| This law states that the change in power is equal to 1 divided by the square of the change in distance |
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Term
|
Definition
| The initial component in a wireless medium. The computer hands the data off and this begins the RF communication |
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Term
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Definition
| "Compares a signal to 1 milliwatt of power. means ""decibels relative to 1 milliwatt."" It is a measurement of power" |
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Term
|
Definition
| "The increase in gain of an antenna, conmpared to the signal of a dipole antenna. Another way of phrasing this is ""decibel gain relative to a dipole antenna""" |
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|
Term
|
Definition
| Units of measure that provide comparative measurement values, not absolute measurements. Decibel is an example |
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Term
|
Definition
| "Gain or increase of power from an antenna when compared to what an isotropic radiator would generate. Another way of phrasing this is ""decibel gain relative to an isotropic radiator""" |
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Term
|
Definition
| Non-profit group devoted to the growth of wireless LANs (WLANs). One of their primary task is to ensure interoperability of WLAN products by providing certification testing |
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Term
|
Definition
| A term describing a behavior of waves. How fast the waves travel, or more specifically, how many waves are generated over a 1-second period of time |
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Term
|
Definition
| height, force, or power of a wave |
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Term
|
Definition
| The relationship between two waves with the same frequency |
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|
Term
| Phase Shift Keying (PSK) |
|
Definition
| Varies the phase of the signal to represent the binary data. State transition technique. determines the data that is being transmitted. one phase can represent a 0 bit and another phase can represent a 1 bit |
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Term
|
Definition
| The distance between similar points on two back-to-back waves. Typically measured from the peak of a wave to the peak of the next wave |
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Term
|
Definition
| "best known for LAN standards. Mission is to ""promote the engineering process of creating, developing, integrating, sharing, and applying knowledge about electro and information technologies and sciences for the benefit of humanity and the profession""" |
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Term
|
Definition
| Method of manipulating a signal so that it can represent multiple pieces of data. It's what changes a signal into a carrier signal. |
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Term
| Federal Communications Commission (FCC) |
|
Definition
| independent United States agency that regulates communications to and from the United States. Regulates radio signals that are used for wireless networking |
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Term
| Frequency Shift Keying (FSK) |
|
Definition
| A current state technique. one frequency can represent a 0 bit and another frequency can represent a 1 bit |
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Term
|
Definition
| global hierarchy that maintains a database for worldwide frequency assignments and coordinates spectrum management through five administrative regions |
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Term
|
Definition
| a modulated signal that is capable of distinguishing between 0s and 1s |
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Term
| Amplitude Shift Keying (ASK) |
|
Definition
| varies the height of a signal to represent binary data. A current state technique. |
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|
Term
|
Definition
| The manipulation of a signal so that the receiving station has a way of distinguishing 0s and 1s |
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Term
|
Definition
| developed Open Systems Interconnection (OSI) model |
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Term
|
Definition
| Starts with a y. A type of semi-directional antenna designed to direct a signal in a specific direction. Used for short to medium-distance communication |
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Term
|
Definition
| When an access point has two antennas and receivers functioning together to minimize the negative effects of multipath |
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|
Term
|
Definition
| An antenna that consists of two elements. A half-wave type antenna consists of two elements, each 1/4 of the wavelength long |
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Term
|
Definition
| A highly-directional antenna that is similiar to the small digital satellite TV antennas that can be seen on the roofs of many houses |
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|
Term
|
Definition
| The measurement of how broad or narrow the focus of an antenna is. Measured both horizontally and vertically |
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|
Term
| highly-directional antenna |
|
Definition
| Strictly used for point-to-point communications, typicall to provide network bridging between two buildings. These provide the most focused, narrow beamwidth of any of the antenna types. There are two types of these: parabolic dish and grid |
|
|
Term
| omni-directional antenna |
|
Definition
| A type of antenna that radiates RF signals in all directions |
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|
Term
|
Definition
| A special type of high-gain, semi-directional antenna that provide a pie-shaped coverage pattern |
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|
Term
| multiple input multiple output (MIMO) |
|
Definition
| Any RF communications system that has multiple antennas at both ends of the communications link and being used concurrently |
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|
Term
|
Definition
| Takes an RF signal and divides it into two or more separate signals |
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|
Term
|
Definition
| small devices about the size of a C-cell battery, with cable connectors on both sides. They absorb energy, decreasing the signal as it travels through. Fixed types provide a set amount of loss. Variable loss types have a dial on it that allows you to adjust the amount of energy that is absorbed |
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|
Term
| voltage standing wave ratio (VSWR) |
|
Definition
| A numerical relationship between the measurement of the maximum voltage along the line (what is generated by the transmitter) and the measurement of the mimimum voltage along the line (what is received by the antenna) |
|
|
Term
|
Definition
| Labeled E-plane, shows the side view of the radiation pattner of the antenna |
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|
Term
|
Definition
| An antenna system made up of multiple antennas that are connected to the signal processor. |
|
|
Term
| semi-directional antenna |
|
Definition
| A type of antenna that is designed to direct a signal in a specifi direction |
|
|
Term
|
Definition
| A type of semi-directional planar antenna designed to direct a signal in a specific direction. Used for short-to medium-distance communications |
|
|
Term
|
Definition
| A device that redirects (shunts) transient currents caused by nearby lighting strikes or ambient static away from your electronic equipment and into the ground |
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|
Term
|
Definition
| Labeled H-plane, shows the top-down view of the radiation pattern of the antenna |
|
|
Term
|
Definition
| refers to the the back of an antenna |
|
|
Term
|
Definition
| When light travels from one point to another, it travels across what is perceived to be an unobstructed straight line |
|
|
Term
|
Definition
| An imaginary football-shaped area that surrounds the path of the visual LOS between two point-to-point antennas |
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|
Term
|
Definition
| A highly-directional antenna taht resembles the rectangular grill of a barbeque, with the edges slightly curved inward. The spacing of the wries on this is determined by the wavelength of the frequencies that the antenna is designed for |
|
|
Term
|
Definition
| The curvature of the earth, which must be considered when installing long distance point-to-point RF communications |
|
|
Term
|
Definition
| A type of semi-directional planar antenna designed to direct a signal in a specific direction. |
|
|
Term
|
Definition
| The orientation of the antenna. Antennas radiate RF signals with the amplitude of the waves fluctuating either vertically or horizontally |
|
|
Term
| Voice over Wi-fi (VoWIP) |
|
Definition
| Any software or hardware that uses voice over IP communications over an 802.11 wireless network. Because of latency concerns, this requires QoS mechanisms to function properly in an 802.11 BSS |
|
|
Term
|
Definition
| A measurement of the amount of user data that successfully traverses the network over a period of time |
|
|
Term
| transmit power control (TPC) |
|
Definition
| Part of the 802.11h amendment. Used to regulate the power levels used by 802.11a radio cards |
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|
Term
| quality of service (QoS) |
|
Definition
| The attempt to prioritize and provide certain levels of predictable throughput along a shared access medium |
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Term
|
Definition
| "A mechanism that allows to technologies to exist. The goal of the 802.11g ""this thing"" is to prevent ERP-OFDM radio cards from transmitting at the same time as DSSS radio cards" |
|
|
Term
| Wired Equivalent Privacy (WEP) |
|
Definition
| A layer 2 encryption method that uses the RC4 streaming cipher |
|
|
Term
| wireless distribution system (WDS) |
|
Definition
| Can connect access points together, using what is referred to as a wireless backhaul |
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|
Term
| Wi-fi Protected Access (WPA2) |
|
Definition
| A more complete implementation of the 802.11i amendment and supports both the CCMP/AES and TKIP/RC4 dynamic encryption key management |
|
|
Term
| Shared Key authentication |
|
Definition
| The more complex of the two 802.11 authentication methods. This uses WEP to authenticate client stations and requires that a static WEP key be configured on both the station and the access point. In addition to WEP being mandatory, authentication will not work if the static WEP keys do not match. |
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|
Term
| Inter Access Point Protocol (IAPP) |
|
Definition
| Announcement and handover processes that result in how APs inform other APs about roamed clients and that define a method of delivery for buffered packets |
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|
Term
| Industrial, Scientific, and Medical (ISM) |
|
Definition
| 902-928 (26 MHz wide) 2.4000-2.4835 GHz (83.5 MHz wide) 5.725-5.875 GHz (150 MHz wide) |
|
|
Term
|
Definition
| The ability for the client stations to transition from one access point to another while maintaining network connectivity for the upper-layer applications |
|
|
Term
|
Definition
| A communication technology that uses a light-based medium |
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|
Term
| Temporal Key Integrity Protocol (TKIP) |
|
Definition
| An enhancement of WEP encryption that addresses many of the know weaknesses of WEP. |
|
|
Term
|
Definition
| Default operational mode of most 802.11 access points. Support for both DSSS and OFDM is enabled, therefore 802.11b and 802.11g clients can communicate with the access point |
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|
Term
| Hybrid Coordination Function Controlled Access (HCCA) |
|
Definition
| "Similar to PCF. Gives the access point the ability to provide for ""prioritization of stations"" via a polling mechanism. Certain client stations are given a chance to transmit before others" |
|
|
Term
| Packet Binary Convolutional Coding (PBCC) |
|
Definition
| A modulation technique that supports data rates of 5.5, 11, 22, and 33 Mbps. Both transmitter and receiver must support the technology to achieve the higher speeds. Was developed by Alantro Communications, which was purchased by Texas Instruments |
|
|
Term
| Point Coordination Function (PCF) |
|
Definition
| An optional 802.11 medium access method that uses a form of polling. Although defined by the standard, the medium access method has not been implemented |
|
|
Term
| Robust Security Network (RSN) |
|
Definition
| A network that only allows for the creation of robust security network associations (RSNAs). This utilizes CCMP/AES encryption as well as 802.1X/EAP authentication |
|
|
Term
|
Definition
| A network environment where wireless mesh routers communicate with each other using proprietary layer 2 routing protocols, creating a self-forming and self-healing wireless infrastructure (a mesh) over which edge devices can communicate |
|
|
Term
|
Definition
| A method of distributing encryption passphrases or keys by manually typing the matching passphrases or keys on both the access point and all client stations that will need to be able to associate to the wireless network |
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|
Term
|
Definition
| The transmission of voice conversations over a data network using TCP/IP protocols |
|
|
Term
|
Definition
| these are responsible for revising and amending the orginal 802.11 standard. They are composed of MAC and PHY. |
|
|
Term
| Orthogonal Frequency Division Multiplexing (OFDM) |
|
Definition
| One of the most popular communication technologies, used in both wired and wireless communications. Is specified in the 802.11a and 802.11g amendments and can transmit at speeds of up to 54 Mbps. Transmits across 52 separate, clsely and precisely spaced frequencies, often referred to as subcarriers |
|
|
Term
| Open System authentication |
|
Definition
| Simpler of the 802.11 authentication methods. It provides authentication without performing any type of client verification. |
|
|
Term
| Counter Mode with Cipher Block Chaining Message Authentication Code Protocol (CCMP) |
|
Definition
| The default encryption method defined under the 802.11i amendment. This method uses AES encryption. |
|
|
Term
| Distributed Coordination Function (DCF) |
|
Definition
| CSMA/CA is provided by this, which is the mandatory access method of the 802.11 standard |
|
|
Term
|
Definition
| Transmission rates specified by the 802.11 standard and amendment, not actual throughput. |
|
|
Term
| High-Rate DSSS (HR-DSSS) |
|
Definition
| The 802.11b 5.5 and 11 Mbps speeds |
|
|
Term
| distribution system (DS) |
|
Definition
| a system used to interconnect a set of basic service sets (BSSs) and intregrated local area networks (LANDs) to create an extended service set (ESS). This consists of a medium used for transport of traffic as well as services used for transport of traffic |
|
|
Term
| Extensible Authentication Protocol (EAP) |
|
Definition
| Used to provide user authentication for an 802.1X port-based access control solution. It is a flexible layer 2 authentication protocol that resides under Point-to-Point (PPP) |
|
|
Term
| dynamic frequency selection (DFS) |
|
Definition
| Also known as dynamic rate shifting, adaptive rate selection, or automatic rate selection. A process that client stations use to shift to lower bandwidth capabilities as they move away from an access point and higher bandwidth capabilities as they move toward an access point. |
|
|
Term
| direct sequence spread spectrum (DSSS) |
|
Definition
| A spead spectrum technology originally specified in the 802.11 standard. Provides 1 and 2 Mbps RF communcations using the 2.4 GHz ISM band. These radio cards are often known as clause 15 devices |
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|
Term
| Extended Rate Physical OFDM (ERP-OFDM) |
|
Definition
| Used to enhance the 802.11b physical layer to achieve greater bandwidth while remaining compatible with the 802.11 MAC. Used exactly as defined in the 802.11a amendment. Data rates of 6, 9, 12, 18, 24, 36, 48, and 54 Mbps are possible. To maintain backward compatability, the DSSS data rates of 1, 2, 5.5, and 11 are supported as well |
|
|
Term
|
Definition
| One of the key components of a wireless security solution. It is achieved by using encryption |
|
|
Term
| Hybrid Coordination Function (HCF) |
|
Definition
| An additional coordination function that is applied in an 802.11e QoS wireless network. Has two access mechanisms to provide QoS: EDCA and HCCA |
|
|
Term
|
Definition
| A port based access control standard. Provides an authorization framework that allows or disallows traffic to pass through a port and thereby access network resources. 3 main components: supplicant, the authenticator, and the authentication server |
|
|
Term
|
Definition
| Proprietary solutions that provide fast and secure 802.11 roaming, which is needed to implement security and time-sensitive applications in a wireless network |
|
|
Term
| Enhanced Distributed Channel Access (EDCA) |
|
Definition
| "An extension of DCF. This medium access method will provide for the ""prioritization of traffic"" via the use of 802.1d priority tags" |
|
|
Term
|
Definition
| A spreading/coding technique used by 802.11 cards |
|
|
Term
|
Definition
| Wireless communication is typically performed within a constrained set of frequencies known as a frequency band. This term is the frequency band |
|
|
Term
| Advanced Encryption Standard (AES) |
|
Definition
| A block cipher that offers much stronger protection than RC4 streaming cipher. Used to encrypt 802.11 wireless data using an encryption method known as CCMP. Encrypts data in fixed data blocks with choices in encryption key strength of 128, 192, or 256 bits |
|
|
Term
| Complementary Code Keying (CCK) |
|
Definition
| A spreading/coding technique used by 802.11b cards to provide higher data rates (HR-DSSS) |
|
|
Term
|
Definition
| Verification of user identity and credentials |
|
|
Term
|
Definition
| The way in which the RF waves move. Varies drastically depending on the materials in the signal's path. Drywall will have a much different effect on an RF signal than metal |
|
|
Term
|
Definition
| Most common RF behavior. Occurs when a signal does not bounce off an object or move around an object |
|
|
Term
|
Definition
| Multiple reflections. 2 ways - First - wave reflects off of minute particles within the medium (smog, sandstorms). Second - occurs when the RF signal encounters some uneven surface (chain-link fence, tree foliage, and rocky terrain. Second kind of scattering can cause a significant downgrade or loss of signal |
|
|
Term
|
Definition
| One of the most important RF propagation behaviors. When a wave hits a smooth object that is larger than the wave itself, depending upon the media, the wave may bounce in another direction |
|
|
Term
|
Definition
| Also known as attenuation. Decrease of amplitude or signal strength |
|
|
Term
|
Definition
| The loss of signal strength caused by the natural broadening of the wave, often referred to as beam divergence. RF signal energy spreads over larger areas as the signal travels farther away from an antenna, and as a result, the strength of the signal attenuates |
|
|
Term
|
Definition
| A time domain tool that can be used to measure how a signal's amplitude changes over time |
|
|
Term
|
Definition
| The increase of a signal's amplitude by the use of an external device |
|
|
Term
|
Definition
| Delay between the reception of the main signal and the reflected signal |
|
|
Term
|
Definition
| frequency domain measurement devices that can measure the amplitude and frequency space of electromagnetic signals. Used to pick up any sources of interference during an 802.11 |
|
|
Term
|
Definition
| Due to the differences in phase of the multiple paths, a combined signal will often attenuate, amplify, or become corrupted. These effect are sometimes called Rayleigh fading, named after British physicists Lord Rayleigh |
|
|
Term
| intersymbol interference (ISI) |
|
Definition
| A type of multipath interference caused by the difference in time between the primary signal and the reflected signals |
|
|
Term
|
Definition
| The movement or motion of the RF waves through the air |
|
|
Term
|
Definition
| The bending of an RF signal around an object |
|
|
Term
|
Definition
| "A single change from up to down to up or a signel change from positive to negative to positive. Also known as a ""cycle.""" |
|
|
Term
|
Definition
| Decrease of amplitude or signal strength. Also known as loss |
|
|
Term
| alternating current (AC) |
|
Definition
| An electrical current with a magnitude and direction that varies cyclically. The shape and form of the signal (waveform) is a sine wave |
|
|
Term
|
Definition
| A propagation phenomenon that results in two or more paths of a signal arriving at a receiving antenna at the same time or within nanoseconds of each other |
|
|
Term
|
Definition
| Increase of a signal's amplitude caused by the use of an amplifier on the wire that connects the transceiver to the antenna. Requires the use of an external power source |
|
|
Term
|
Definition
| The area directly behind an RF obstruction. Depending upon the change in direction and velocity of the diffracted signals, the area of the RF shadow can become a dead zone of coverage or still possibly receive degraded signals |
|
|
Term
|
Definition
| Increase of amplitude or signal strength. 2 types |
|
|
Term
|
Definition
| Position and direction of the electric field (E-field) as referenced to the surface of the earth. Vertical polarization is when the E-field is perpendicular to the earth. Horizontal polarization is when the E-field is parallel to the earth |
|
|
Term
|
Definition
| A standard measurement of frequency |
|
|
Term
|
Definition
| The bending of an RF signal as it passes through a medium with a different density, thus causing the direction of the wave to change. Most commonly occurs as a result of atmospheric conditions |
|
|
Term
|
Definition
| The level of background noise |
|
|
Term
|
Definition
| Accomplished by focusing the RF signal with the use of an antenna. Antennas with passive gain do not need an external power source. Focus of the signal is more powerful in one direction than another |
|
|
Term
| Wireless Personal Area Network (WPAN) |
|
Definition
| wireless computer network used for communication between computer devices with in close range. Devices such as laptops, PDA's and telephones. Must common is Bluetooth and infrared |
|
|
Term
| Integration Service (IS) |
|
Definition
| Enables delivery of MSDU's between distribution system and non-IEEE-802.11 LAN's, via a portal |
|
|
Term
|
Definition
| common term used to refer to a client station that is configured to connect to a BSS or ESS |
|
|
Term
| Distribution System Medium (DSM) |
|
Definition
| Logical physical medium used to connect AP's. Normally the DSM is an 802.3 ethernet backbone. Medium can also be wireless or some other type of medium. |
|
|
Term
| Service Set Identifier (SSID) |
|
Definition
| Network name used to ID an 802.11 wireless network. The name is a logical name of WLAN. It can be made up by as many as 32 Characters and is case sensitive |
|
|
Term
| Basic Service Area (BSA) |
|
Definition
| Physical area of coverage provided by an AP. Clients can move within this area and maintain coverage with AP as long as radios remaine above RSSI thresholds |
|
|
Term
| Basic Service Set (BSS) |
|
Definition
| Involves communication between a single AP and client station that are associated to the AP. |
|
|
Term
| MAC Service Data Unit (MSDU) |
|
Definition
| contains data from the LLC and layers 3-7. It is the data payload that contains the IP packet plus some LLC data |
|
|
Term
| Basic Service Set Identifier (BSSID) |
|
Definition
| is a 48-bit MAC address used as a unique ID of basic service set. In either BSS or ESS the BSSID is simply the MAC address of a single AP. In IBSS the BSSID is a Virtual Address |
|
|
Term
| Distribution System Services (DSS) |
|
Definition
| System service built inside of an autonomous AP or WLAN controller usually in the form of software. DSS is used to transport 802.11 traffic. |
|
|
Term
| Wireless Metropolitan area Network (WMAN) |
|
Definition
| Provides coverage to a metropolitan area such as a city and surrounding suburbs. The topology associated with WMAN is 802.16 standard. Defines broadband wireless access and is refered to as WiMAX |
|
|
Term
| Extended Service Set (ESS) |
|
Definition
| Invovles communication between multiple AP's that share network infastructure. It is 1 or more BSS that share a distribution system medium |
|
|
Term
|
Definition
| A timer mechanism that maintains a prediction of future traffic on medium based on duration value information seen in previous frame transmission. When a radio is not transmitting it's listening. When listening it and hears frame from another station it looks at the header and determines the Duration/ID contains a duration value or ID Value. If it contains duration value the listening station will set it's NAV timer to this value. Listening station will then use the NAV as a countdown timer, knowing that the RF medium should be busy until the countdown reaches 0. |
|
|
Term
| Hybrid Coordinator (HC) |
|
Definition
| QoS-aware centralized coordinator that works within HCCA. HC is built into AP and has a higher priority of access to the wireless medium. Using this higher priority level, it can allocate TXOP's to itself and other stations to provide a limited-duration controlled access phase (CAP) providing contention-free transfer of QoS data. |
|
|
Term
| Hybrid Coordination Function Controlled Channel Access (HCCA) |
|
Definition
| defined by 802.11e. HCCA is similar to PCF, HCCA gives the AP the ability to provide for prioritization of stations via a polling mechanism. Certain client stations are given a chance to transmit before others |
|
|
Term
|
Definition
| Occurs when the AP is functioning in DCF mode |
|
|
Term
|
Definition
| One of six control frames and one key component of CSMA/CA. Only way for a station to know that a frame was transmitted properly is to receive from the receiving station an ACK notification. |
|
|
Term
| Clear Channel Assessment (CCA) |
|
Definition
| A layer 1 process that determines whether the RF medium is busy. This is performed by 802.11 radios prior to transmitting data. |
|
|
Term
|
Definition
| The polling device in an 802.11 PCF network. |
|
|
Term
|
Definition
| A field in an 802.11 frame header that is physically used to set the NAV timer in other stations. Used with virtual carrier-sense |
|
|
Term
| Transmit Opportunity (TXOP) |
|
Definition
| A limited-duration controlled access phase, providing contention-free transfer of QoS data |
|
|
Term
|
Definition
| After a station has waited while performing both virtual and physical carrier-senses, the station may contend for the medium during a window of time known as the contention window. |
|
|
Term
|
Definition
| A period of time that differs between the different spread spectrum technologies. It is a large enough time to allow for receive-to-transmit radio turnaround, MAC processing, and clear channel assessment (CCA) |
|
|
Term
|
Definition
| Media access control method used by 802.11 networks |
|
|
Term
| Block Acknowledgement (BA) |
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Definition
| Improves channel efficiency by aggregating serveral acknowledgements into a single ACK frame. |
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Term
| Contention-free Period (CFP) |
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Definition
| Occurs when the AP is functioning in PCF mode. During the CFP, the AP polls only clients in PCF mode about their intention to send data. This is a method of prioritizing clients. |
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Term
|
Definition
| Differentiated access for stations provided by EDCA. User priority uses eight levels. The user priority tags are identical to 802.1D priority tags. |
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Term
|
Definition
| A period of time that exists between transmissions of wireless frames. |
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Term
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Definition
| Performed constantly by all stations that are not transmitting or receiving data. determines whether a frame transmission is inbound for a station receive or whether the medium is busy before transmitting. This is known as the clear channel assessment (CCA) |
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Term
| Network Allocation Vector (NAV) |
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Definition
| A timer mechanism that maintains a prediction of future traffic on medium based on duration value information seen in previous frame transmission. When a radio is not transmitting it's listening. When listening it and hears frame from another station it looks at the header and determines the Duration/ID contains a duration value or ID Value. If it contains duration value the listening station will set it's NAV timer to this value. Listening station will then use the NAV as a countdown timer, knowing that the RF medium should be busy until the countdown reaches 0. |
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Term
|
Definition
| The Wi-Fi alliance oversees the WMM-PS (Power Save) certification, which uses 802.11e mechanisms to increase the battery life via advanced power-saving mechanisms. The Wi-Fi Alliance's WMM Power Save certification is based on automatic power save delivery (APSD) |
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Term
| Scheduled Automatic power save delivery (S-APSD) |
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Definition
| An enhanced power MGMT method introduced by the IEEE 802.11e amendment |
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Term
| Traffic Indication Map (TIM) |
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Definition
| used when stations have enabled power save mode. The TIM is a list of all stations that have undelivered data buffered on the AP waiting to be delivered. Every beacon will include the AID of the station until the data is delivered. |
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Term
| Logical Link Control (LLC) |
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Definition
| The upper portion of the Data-link layer is the IEE 802.2 Logical Link Control (LLC) sublayer, which is identical for all 802-based networks, although not used by all IEEE 802 networks. |
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Term
| PLCP Service Data Unit (PSDU) |
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Definition
| Equivalent to the MPDU. The MAC layer referes to the frame as the MPDU, while the Physical layer refers to this same exact frame as the PSDU |
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Term
| Short interframe space (SIFS) |
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Definition
| A short gap or period of time that is used during transmission of data |
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Term
| Unscheduled Automatic Power Save Delivery (U-APSD) |
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Definition
| an enhanced power-MGMT method introduced by IEEE 802.11e amendment. The Wi-Fi Alliance's WMM power save (WMM-PS) certification is based on U-APSD |
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Term
| Request to send/Clear to send (RTS/CTS) |
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Definition
| A mechanism that performs a NAV distribution and helps to prevent collisions from occurring. This NAV distribution reserves the medium prior to the transmission of the data frame. RTS/CTS can be used to discover hidden node problems. RTS/CTS is one of the two protection mechanisms used in mixed-mode environment |
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Term
| Power Save Multi Poll (PSMP) |
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Definition
| Power MGMT method defined for use by HT radios. PSMP is an extension of automatic power save delivery (APSD) that was defined by the 802.11e amendment |
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Term
| Physical Layer Convergence Procedure (PLCP) |
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Definition
| The upper portion of the physical layer. PLCP prepares the frame for transmission by taking the frame from the MAC sublayer and creating the PLCP Protocol Data Unit (PPDU) |
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Term
|
Definition
| Prob request management frame with no SSID information |
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Term
|
Definition
| When a client station decides to roam to a new AP, it will send a reassociation request frame to the new AP. It is called a reassociation not because it is reassociating to the AP, but because it is reassociating to the SSID of the wireless network |
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Term
|
Definition
| optional mode for 802.11 stations. A wireless station can shut down some of the transceiver components for a period of time to conserve power. The station indicates that it is using Power Save Mode by changing the value of the Power Mgmt field to 1 |
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Term
|
Definition
| MGMT frame that is transmitted during active scanning. A client station that is looking for an SSID sends a probe request. AP's that hear the probe request will send a probe response, notifying the client of the AP presence. If a client station receives probe responses from multiple AP's, signal strength and quality characteristics are typically uses by the client station to determine which AP has the best signal and thus which AP to connect to. |
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Term
| PLCP Protocol Data Unit (PPDU) |
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Definition
| When the PLCP receives the PSDU, it prepares it to be transmitted and creates the PPDU. The PLCP adds the preamble and PHY header to the PSDU |
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Term
| Spatial multiplexing power save (SM Power Save) |
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Definition
| Power-saving mechanism used to allow a MIMO 802.11n device to power down all but one of it's radios |
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Term
| Physical Medium Dependent (PMD) |
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Definition
| The lower portion of the Physical layer. the PMD sublayer modulates and transmits the data as bits |
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Term
| Integration Services (IS) |
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Definition
| Enables delivery of MSDU's between the distribution system (DS) and a non-IEEE-802.11 LAN via a portal |
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Term
|
Definition
| MGMT frame that is transmitted during active scanning. After a client station sends a probe request AP's that hear the probe request will send a probe response, notifying the client of the AP's presence. The information that is contained inside the body of the probe response frame is the exact same information that can be found in a beacon frame with the exception of the TIM |
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Term
| MAC Protocol Data Unit (MPDU) |
|
Definition
| An 802.11 frame. The components include a MAC header, an MSDU (Data Payload) and the trailer |
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Term
|
Definition
| Majority of the frame types in an 802.11 network. Used by wireless stations to join and leave the network. Another name is Management MAC Protocol Data Unit MMPDU. Mgmt frames do not carry any upper-layer info. There is no MSDU encapsulated in the MMPDU frame body, which carries only L2 information fields and information elements |
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Term
|
Definition
| In order for a station to be able to connect to an AP, it needs to first discover an AP. Passive scanning involves the client station listening for beacon frames that are continuously being sent by the AP. |
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Term
|
Definition
| A bit in the 802.11 MAC header that is used by the client station to notify the AP that the station is going into Power Save Mode |
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Term
|
Definition
| Help with the delivery of data frames. Control frames must be able to be heard by all stations; therefore, they must be transmitted at one of the basic rates. Control frames are also used to clear the channel, acquire the channel, and provide unicast frame ACK's. They contain L2 header information. |
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Term
| Announcement traffic indication message (ATIM) |
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Definition
| A unicast frame that is used in an IBSS network when Power Save Mode is enabled. If a station has buffered data for another station it will send an ATIM frame to the other station, informing it that it must stay awake until the next ATIM window so that it can receive the buffered data. Any station that either has buffered data for another station or has received an ATM will stay awake so that the buffered data can be exchanged. |
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Term
|
Definition
| unit of data at the Data-Link Layer |
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Term
|
Definition
| A notification frame used to terminate an authentication. Because authentication is prerequisite for association, disassociation will also occur. Deauthentication cannot be refused by either party |
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Term
|
Definition
| Carry the actual data that is passed down from the higher-layer protocols |
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Term
|
Definition
| The set of data rates that a client station must be capable of communicating with in order to successfully associate with an AP. Basic rates are required rates with a BSS. |
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Term
|
Definition
| Fixed-length mandatory fields in the body of management frame. |
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Term
|
Definition
| Variable-length fields that are optional in the body of management frame |
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|
Term
| Delivery traffic indication message (DTIM) |
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Definition
| A special type of TIM that is used to ensure that all stations are awake when multicast or broadcast traffic is sent |
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Term
|
Definition
| In order for a station to be able to connect to an AP, it needs to first discover an AP. Active scanning is one of the methods that stations use to discover AP's. The station and access point will exchange probe requests and probe responses to establish the capabilities of the basic service set. |
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|
Term
| Frame check sequence (FCS) |
|
Definition
| The extra characters added to a frame and used for error detection and correction |
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|
Term
|
Definition
| A notification frame used to terminate an association. A polite way of terminating the association. Disassociation cannot be refused by either party |
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Term
|
Definition
| After a station has authenticated with the AP the next step is for it to associate with the AP. When a client station associates, it becomes a member of a BSS. Association means that the client station can send data through the AP and on to the Distribution System Medium. |
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Term
|
Definition
| Default power management mode for most 802.11 stations. When a station is set for active mode, the wireless station is always ready to transmit or receive data. Active mode is sometimes referred to as Continuous aware mode, and it provides no battery conservation. In the MAC header of an 802.11 frame, the Power management field is 1 bit in length and is used to indicated the power-magagement mode of the station. A value of 0 indicated that the station is in active mode. Stations running in Active mode will achieve higher throughput than stations running in power save mode, but the battery life will typically be much shorter. |
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Term
|
Definition
| A protection mechanism for mixed-mode environments. One of the benefits of using CTS-to-self over RTS/CTS as a protection mechanism is that the throughput will be higher. Because there are fewer frames being sent |
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|
Term
|
Definition
| Probe request with specific SSIC |
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|
Term
| Automatic Power Save Delivery (APSD) |
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Definition
| an enhanced power-management method introduced by 802.11e amendment. |
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Term
| Association Identifier (AID) |
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Definition
| Any time a station associates to an AP, the station receives an AID. The AP uses this AID to keep track of the stations that are associated and the members of the BSS. |
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Term
| Beacon Management Frame |
|
Definition
| One of the most important 802.11 frame types. Commonly referred to as the beacon. Beacons are essentially the heartbeat of the wireless network. They are sent only by the AP of a BSS. Client stations transmit beacons only when participating in an IBSS. Each beacon contains a time stamp, which the client stations use to keep their clocks in synch with the AP. |
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|
Term
|
Definition
| A set of configuration parameters that are configured on the WLAN controller The profile parameters can include the WLAN logical name (SSID), WLAN security settings, VLAN assignment, and QoS parameters. |
|
|
Term
| Wireless Zero configuration (WZC) service |
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Definition
| The most widely used client utility is an integrated OS client utility, more specifically known as the WZC service utility that is enabled by default in Windows XP. |
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|
Term
|
Definition
| A WLAN controller and multiple AP's using sector antennas all combined in a single hardware device |
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|
Term
|
Definition
| A wireless network configuration that connects only two devices together. This is typically a wireless bridge link. |
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|
Term
| Radio frequency spectrum management (RFSM) |
|
Definition
| Software and hardware solutions that can dynamically change the configuration of lightweight or autonomous AP's based on accumulated RF information gathered from the AP's radio cards. Based on the accumulated RF information, the centralized device controls the AP's and adjusts their power and channel settings, dynamically changing RF coverage cells |
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|
Term
|
Definition
| The BSSID is typically the MAC address of the AP's radio card and the L2 identifier of the BSS. Because AP's are capable of advertising multiple SSIDs, and because each SSID requires a separate BSSID, the AP will generate virtual BSSID addresses |
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Term
| Point-toMultipoint (PtMP) |
|
Definition
| A wireless network configuration that has a central communications device such as a bridge of an AP providing connectivity to multiple devices such as the other bridges or clients |
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|
Term
|
Definition
| A hardware standard that is replacing PCMCIA cards |
|
|
Term
|
Definition
| An environment in which a WLAN controller is a centralized device that can dynamically change the configuration of the lightweight AP based on accumulated RF information gathered from the AP's radio cards. |
|
|
Term
| Software defined radio (SDR) |
|
Definition
| A future technology that will be able to dynamically switch across a wide range of frequency bands, transmission techniques, and modulation schemes so that a single radio could replace multiple products. |
|
|
Term
|
Definition
| The PC Card standard specifies 3 types of PC Cards. The 3 card types are the same length and width and use the same 68-pin connector. The thickness of the cards are follows: Type I = 3.3 mm, Type II = 5.0 mm, and Type III = 10.5 mm. |
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|
Term
| Enterprise encryption gateway (EEG) |
|
Definition
| A specialty 802.11 device that provides for segmentation and encryption. The EEG typically sits behind several fat access points and segments the wireless network from the protected wired network infrastructure. Proprietary encryption technology using the AES algorithm at Layer 2 is provided by the enterprise encryption gateway |
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Term
| Wireless network management system (WNMS) |
|
Definition
| A central management device originally used to configure and maintain as many as 5,000 autonomous APs. A WNMS can be either a hardware appliance or a software solution. The current WNMS servers are used to manage multiple WLAN controllers from a single vendor and many also be used to manage other vendors' WLAN infrastructure, including autonomous APs. |
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|
Term
| Enterprise wireless gateway (EWG) |
|
Definition
| A specialty 802.11 device used to segment autonomous AP's from the protected wired network infrastructure. An EWG can segment the unprotected wireless network from the protected wired network by acting either as a router or a VPN endpoint and/or as a firewall |
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|
Term
| Generic routing Encapsulation (GRE) |
|
Definition
| A process in which frames such as 802.11 frames are encapsulated in a packet, transmitted between two devices on a network, and then removed from the packet and forwarded. |
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|
Term
|
Definition
| With this type of WLAN architecture, some of the MAC services are handled by the WLAN controller and some are handled by the lightweight AP. For example, integration service (IS) and Distribution system service (DSS) are handled by the controller. WMM QoS methods are usually handled by the controller. Depending on the vendor, encryption of 802.11 data frames might be handled by the controller or by the AP. Some 802.11 management frames such as beacons and ACKs might orginate at the AP instead of the WLAN controller |
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|
Term
| Residential wireless gateway (RWG) |
|
Definition
| A fancy term for a home wireless router, the main function of residential wireless gateway is to provide shared wireless access to a SOHO Internet connection while providing a level of security from the Internet. These SOHO Wi-Fi routers are generally inexpensive yet surprisingly full featured. |
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|
Term
| Role-based access control (RBAC) |
|
Definition
| RBAC is an approach to restricting system access to authorized users. The three main components of an RBAC approach are users, roles and permissions. Separate roles can be created such as the sales role or the marketing role. Individuals or groups of users are assigned to one of these roles. Permissions can be defined as firewall permissions, layer 2 permissions, layer 3 permissions, and bandwidth permissions and can be time based. The permissions are then mapped to the roles. When wireless users authenticate via the WLAN, they inherit the permissions of whatever roles they have been assigned to. |
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|
Term
|
Definition
| Wireless bridges support two major configuration settings:Root and nonroot. Bridges work in a parent/child type of relationship. So think of the root bridge as the parent and the nonroot as the child. |
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|
Term
|
Definition
| Multiple SSIDs configured on a single physical AP, where each SSID is mapped to a unique BSSID |
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|
Term
|
Definition
| A peripheral expansion slot often found on handheld PDA's. |
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|
Term
|
Definition
| WLAN controllers are used in a centralized WLAN architecture together with lightweight AP's, known as thin APs. All the intelligence resides in the controller and all of the AP configs settings such as channel and power are distributed to the lightweight APs from the controller and stored in the RAM of the lightweight AP. Encryption and Decryption capabilities might reside in the centralized controller or may still be handled by the lightweight APs, depending on the vendor. DSS and IS function within the Controller. Also known as wireless switch, controllers provide AP management, user management, RF spectrum planning and management, L2 security, L3 security, captive portal, VRRP redundancy, WIDS, and VLAN segmentation. Another major advantage of the controller model is most of the controllers support some sort of fast secure roaming, which can assist in resolving latency issues often associated with roaming. |
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|
Term
| Single channel architecture (SCA) |
|
Definition
| A WLAN architecture in which all AP's in the network can be deployed on one channel in either the 2.4Ghz or 5 GHz frequency bands. Uplink and Downlink transmissions are coordinated by a WLAN controller on a single 802.11 channel in such a manner that the effects of co-channel and adjacent-channel interference are minimized. |
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|
Term
|
Definition
| A small form factor PCI expansion card. The mini PCI is a variation of the Peripheral Component Interconnect (PCI) bus technology and was designed for use mainly in laptops. A mini PCI radio is often used inside AP's and is also the main type of radio used by manufacturers as the internal 802.11 wireless adapter inside laptops |
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|
Term
| Lightweight Access Point |
|
Definition
| Lightweight AP's are used in a centralized WLAN architecture together with WLAN controllers. A lightweight AP has minimal intelligence and is functionally just a radio card and an antenna. All the intelligence resides in the centralized WLAN controller, and all of the AP configuration settings such as channel and power are distributed to the lightweight AP's from the WLAN controller and stored in the RAM of the lightweight AP. The encryption and decryption capabilities might reside in the centralized WLAN controller or may still be handled by the lightweight APs, depending on the vendor. Lightweight APs tunnel 802.11 traffic to the WLAN controller which is typically deployed at either the distribution or core layer. |
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|
Term
| Bridged Virtual Interface (BVI) |
|
Definition
| Autonomous AP contain at least two physical interfaces, usually RF radio card and 10/100BaseT port. The majority of the time, these physical interfaces are bridged together by a virtual interface known as BVI. The BVI is assigned an IP address that is shared by two physical interfaces |
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|
Term
|
Definition
| A peripheral expansion slot often found on handheld PDA, laptops and other mobile devices |
|
|
Term
|
Definition
| A group of integrated circuits designed to work together. Many 802.11 chipset manufactures exist and sell their technology to the various radio card manufacturers. |
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|
Term
|
Definition
| A wireless architecture that consists of groups of Autonomous AP's with WLAN controller intelligence and capabilities |
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|
Term
| Control and Provisioning of Wireless Access Points (CAPWAP) |
|
Definition
| A set of standards proposed by the IETF for WLAN controller protocols. |
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|
Term
| Distributed Data Forwarding (DDF) |
|
Definition
| The use of multiple wireless controllers as data distribution gateways onto the wired network |
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|
Term
| Cooperative Control Access Point (CC-AP) |
|
Definition
| An AP that combines an autonomous AP with a suite of Cooperative control protocols, but without requiring a WLAN controller |
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|
Term
|
Definition
| Software used to configure a wireless client card. The software interface will usually have the ability to create multiple connection profiles. Configuration settings of a client utility typically include the SSID, transmit power, security settings, 802.11e/QoS capabilities, and power management. |
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|
Term
|
Definition
| Traditional AP. Contains at least two physical interfaces, usually an RF radio card and 10/100BaseT port. All configuration settings exist in the AP itself, and therefore, management and configuration occurs at the access layer. All encryption and decryption mechanisms and MAC layer mechanisms also operate within the autonomous AP. The DSS and IS function within an autonomous AP. |
|
|
Term
|
Definition
| communicate with each other by using proprietary L2 routing protocols, creating a self-forming and self-healing wireless infrastructure (a mesh) over which edge devices can communicate |
|
|
Term
|
Definition
| When an 802.1X/EAP solution is deployed, a device that blocks or allows traffic to pass through its port secuirty is known as the authenticator. Authentication traffic is normally allowed to pass through the authenticator while all other traffic is blocked until the identity of the supplicant has been verified. |
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|
Term
| Wi-Fi Protected Access 2 (WPA2) |
|
Definition
| is based on security mechanisms that were orginally defined in the IEEE 802.11i amendment defining a robust security network (RSN). 2 versions of WPA2 exist. WPA2-personal defines security for a small office, home office SOHO ennvironment, and WPA2-Enterprise defines stronger secuirty for enterprise corportate networks. Each certified product is required to support WPA2-Personal or WPA2-Enterprise |
|
|
Term
|
Definition
| Algorithm is a streaming cipher used in technologies that are often used to protect Internet traffic, such as Secure Sockets Layer (SSL). The RC4 algorithm is used to protect 802.11 wireless data and is incorporated into two encryption methods known as WEP and TKIP |
|
|
Term
|
Definition
| Under the 802.11i amendment, two stations (STAs) must establish a procedure to authenticate and associate with each other as well as create dynamic encryption keys through a process known as the 4-Way Handshake. |
|
|
Term
|
Definition
| When an 802.1X/EAP solution is deployed, a host with software that is requesting authentication and access to network resources is known as the supplicant |
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|
Term
| Internet Protocol Secuirty (IPsec) |
|
Definition
| is a Layer 3 VPN technology. IPsec can use RC4, DES, 3DES and AES ciphers for encryption. It provides for encryption, encapsulation, data integrity, and device authnetication. |
|
|
Term
| robust security network associations (RSNAs) |
|
Definition
| As defined by the 802.11i security amendment, two stations (STAs) must establish a procedure to authenticate an associate with each other as well as create dynamic encryption keys through a process known as 4-Way Handshake. This association between two stations is referred to as a robust security network association (RSNA) |
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|
Term
| Message Integrity Check (MIC) |
|
Definition
| TKIP uses a data integrity check known as Message Integrity Check (MIC) to mitigate known bit-flipping attacks against WEP. The MIC is sometimes referred to by the nickname Micheal. |
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|
Term
| Counter Mode with Cipher Block Chaining Message Authentication Code (CCMP) |
|
Definition
| The default encryption method defined under 802.11i amendment. This method uses the AES Cipher. CCMP/AES uses a 128-bit encryption key size and encrypts in 128-bit fixed-length blocks. An 8-byte Message Integrity Check is used that is considered much stronger than the one used in TKIP. CCMP/AES is the default encryption methoid defined by WPA2 |
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|
Term
| Authentication Server (AS) |
|
Definition
| When 802.1X/EAP solution is deployed, an authentication server validates the credentials of the supplicant that is requesting access and notifies the authenticator that the supplicant has been authorized. The authentication server will maintain a user database or may proxy with an external user database to authenticate user credentials. |
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|
Term
| Authorization, Authentication and Accounting (AAA) |
|
Definition
| is a secuirty concept. Authorization involves granting access to network resources and services. Before authorization to network resources can be granted, proper authentication must occur. Authentication is the verification of user identity and credentials. Accounting is tracking the use of network resources by users. It is an important aspect of network secuirty, used to keep a paper trail of who used what resources and when and where. |
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|
Term
| Initialization Vector (IV) |
|
Definition
| The IV is utilized by the RC4 steaming chipher that WEP encryption uses. The IV is a block of 24 bits that is combined with a static key. It is sent in cleartext and is different on every frame. The effective key strength of combining the IV with the 40-bit static key is 64-bit encryption. TKIP uses an extended IV. |
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|
Term
| Point-to-Point Tunneling Protocol (PPTP) |
|
Definition
| PPTP is a layer 3 VPN technology. It uses 128-bit Microsoft point-to-point encryption (MPPE), which uses the RC4 algorithm. MPPE encryption is considered adequate but not strong. PPTP also uses MS-CHAP version 2 for user authentication, which is susceptible to offline dictionary attacks. |
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|
Term
| transition security network (TSN) |
|
Definition
| An 802.11 wireless network that allows for the creation of pre-robust security network associations (pre-RSNAs) as well as RSNAs is known as a transition security network. A TSN supports 802.11i-defined security as well as legacy security such as WEP within the same BSS |
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|
Term
| Wi-Fi Protected Access (WPA) |
|
Definition
| Prior to the ratification of the 802.11i amendment, the Wi-Fi alliance introduced WPA certification as a snapshot of the not yet released 802.11i amendment, supporting only the TKIP/RC4 dynamic encryption key mangement. 802.1X/EAP authentication was required in the enterprise, and passpharse authentication was required in a SOHO environment. |
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|
Term
| port-based access control |
|
Definition
| The 802.1X standard defines port-based access control. 802.1X provides an authorization framework that allows or disallows traffic to pass through a port and thereby access network resources. 802.1X defines two virtual ports: an uncontrolled port and a controlled port. The uncontrolled port allows EAP authentication traffic to pass through, while the controlled port blocks all other traffic until the supplicant has been authenticated. |
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|
Term
|
Definition
| After an EAP frame exchange where mutal authentication is required, both the AS and the supplicant known infomration about each other because of the exchanging of credentials. This newfound information is used as seeding material or keying material to generate a matching dynamic encryption key for both the supplicant and the authentication server. These dynamic keys are generated per session per user, meaning that every time a client station authenticates, a new key is generated and every user has a unique and seperate key. |
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|
Term
| Microsoft Point-to-Point encryption (MPPE) |
|
Definition
| MPPE is a 128-bit encryption method that uses the RC4 algorithm. MPPE is used with P2P tunneling protocol (PPTP) VPN technology. |
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|
Term
| Wireless intrusion prevention system (WIPS) |
|
Definition
| is a wireless intrusion detection system (WIDS) that is capable of mitigating attacks from rogue APs. WIPS use spoofed deauthentication frames, smnp, and prorietary methods to effectively render a rogue access devices useless and protect the network backbone. |
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|
Term
|
Definition
| Also known as the evil twin attack, occurs when a hacker disrupts communications between client stations and a legitimate AP. Client stations lose their connection to the legitimate AP and reconnect to the hacker's access point. The hacker AP hijacks the client stations at Layer 1 and Layer 2, allowing the hacker to proceed with Peer-to-Peer attacks. |
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|
Term
| Public Secure Packet Forwarding (PSPF) |
|
Definition
| PSPF is a feature that can be enabled on WLAN AP or switches to block wireless clients from communicating with other wireless clients on the same wireless segment. With PSPF enabled, client devices cannot communicate with other client devices on the wireless network. PSPF is a term most commonly used by cisco; other vendors have similar capabilities under the different names. PSPF is useful in preventing peer-to-peer attacks through an AP. |
|
|
Term
|
Definition
| A functional security policy defines the technical aspects of wireless security. The functional security policy establishes how to secure the wireless network in terms of what solutions and actions are needed. A functional policy defines essentials, baseline practices, design, implementation, and monitoring procedures. |
|
|
Term
|
Definition
| The evil twin attack, also known as wireless hijacking, occurs when a hacker disrupts communication between client stations and a legitmate AP. Client stations lose thier connection to the legitimate AP and reconnect to the evil twin access point. The evil twin hijacks the client stations at layer 1 and layer 2, allowing the hacker to proceed with peer-to-peer attacks |
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|
Term
|
Definition
| After completing a wireless hijacking attack at a hotspot, a hacker may also use web server software and captive portal software to perform a Wi-Fi phishing attack. After client stations have been hijacked to an evil twin access point, they are redirected to a login web page that looks exactly like a hotspots login page. The hacker's fake login page will request a credit card number from the hijacked user. Phishing attacks are common on internet and are now appearing at Wi-Fi hotspots |
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|
Term
|
Definition
| Is not considered malicious and is also often referred to as wardriving. Software utilities known as WLAN discovery tools exist for the purpose of finding open WLAN networks. Wardriving is strictly the act of looking for wireless networks, usually while in a moving vechicle. The most common wardriving software tool is freeware program called NetStumbler |
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|
Term
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Definition
| A general wireless security policy establishes why a wireless security policy is needed for an organization. The general wireless security policy defines a statement of authority, applicable audience, violating policy procedures, risk assessment, threat analysis, and auditing |
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Term
| Denial of service (DoS) |
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Definition
| Any individual with ill intent can temporarily disable Wi-Fi network by preventing legitimate wireless users from accessing network resources. Layer 1 and Layer 2 attacks exist that can deny 802.11 wireless services to legitimate authorized users. 802.11 DoS attacks cannot be prevented, but they can be detected with the proper intrusion detection tools. |
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Term
| Management Frame Protection (MFP) |
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Definition
| Techniques used to deliver management frames in a secure manner, with the hope of preventing many Layer 2 denial-of-service attacks. |
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Term
| Distributed spectrum analysis system (DSAS) |
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Definition
| A centralized server that uses remote hardware spectrum analyzer sensors. |
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Term
| Malicious eavesdropping |
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Definition
| The unauthorized use of protocol analyzers to capture wireless communications is known as malicious eavesdropping and is typically considered illegal. Most countries have laws making it unlawful to listen in on any type of electromagnetic communications such as phone conversations. Unauthorized monitoring of 802.11 wireless transmissions is considered malicious and normally illegal. The most common target of malicious eavesdropping attacks is public access hotspots |
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Term
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Definition
| is the act of looking for wireless networks, usually while in a moving vehicle. Software utilities known as WLAN discovery tools exist for the purpose of finding open WLAN networks. The most common wardriving software tool is a freeware program called NetStumbler. |
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Term
| Wireless intrusion detection system (WIDS) |
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Definition
| is a client/server solution that is used to constantly monitor for 802.11 wireless attacks such as rogue APs, MAC spoofing, Layer 2 DoS, and so on. A WIDS usually consists of three components: a sever, sensors, and monitoring software. Wireless intrusion detection uses polices and alarms to properly classify attacks and to alert administrators to potential attacks |
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Term
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Definition
| A technique used to manipulate people into divulging confidential information such as computer passwords. |
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Term
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Definition
| In a MIMO system, multiple spatial streams are sent with different (unequal) modulation |
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Term
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Definition
| Frames that are sent by 802.11n HT radios with transmit beamforming capabilites. Sounding frames are used to exchange implicit and explicit feedback. The transmitter is considered the beamformer, while receiver is considered the beamformee. The beamformer and the beamformee work together to educate each other about the characteristics of the MIMO channel. the beamformer will send a sounding request frame and will make phase adjustments based on the information that is returned in sounding response frame from the beamformee. any frame can be used as a sounding frame. |
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Term
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Definition
| Antenna diversity that results in multiple RF streams following different paths to the receiver because of the space between the transmitting antennas. Each stream travels a different path, because there is at least a half-wavelength of space between the multiple transmitting antennas. |
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Term
| Single-input single-output (SISO) |
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Definition
| A system that makes use of single radio chain. |
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Term
| Transmit beamforming (TxBF) |
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Definition
| Multiple antennas that are connected to a signal processor. The processor feeds the individual antennas with signals of different relative phases, creating a directed beam of RF signal aimed at the client device. The 802.11n draft amendment proposes this as an optional PHY capability. Technology uses phased-array antenna technology and is often referred to as smart antenna technology. |
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Term
| Reduced interframe space (RIFS) |
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Definition
| A new interframe space that is used in 802.11n and is even shorter than a SIFS. A RIFS interval can be used in place of SIFS interval, resulting in less overhead during a frame burst |
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Term
| Maximal ratio combining (MRC) |
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Definition
| A signal-processing technique used to combine multiple received signals, which looks at each unique signal and optimally combines them in a method that is additive as opposed to destructive. |
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Term
| phased coexistence operation (PCO) |
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Definition
| An optional 802.11n mode of operation that divides time and alternates between 20 MHz and 40 MHz transmissions |
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Term
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Definition
| When receiving, multiple copies of the same signal arrive at the receiver antennas with different amplitudes. The signal with the best amplitude is chosen, and the other signals are ignored. Also used when transmitting, but only one antenna is used. the transmitter will transmit out of the diversity where the best amplitude signal was last heard. |
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Term
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Definition
| Occurs in 802.11n when a transmitter and receiver work together to educate each other about the characteristics of the MIMO channel. The transmitter will make phase adjustments based on the information that is returned from the receiver. When using implicit feedback, the beamformer receives long training symbols transmitted by the beamformee, which allow the MIMO channel between the beamformee and beamformer to be estimated. |
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Term
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Definition
| An 802.11n protection mode that is used when one or more non-HT stations are associated to the HT access point. |
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Term
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Definition
| MIMO radios transmit multiple radio signals at the same time and take advantage of multipath. Each individual radio signal is transmitted by a unique radio and antenna of the MIMO system. Each independent signal is known as a spatial stream, and each stream can contain different data than the other streams transmitted by one or more of the other radios. Each stream will also travel a different path because there is at least a half-wavelength of space between the multiple transmitting antennas. |
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Term
| Multiple traffic ID block ACK (MTBA) |
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Definition
| A block acknowledgment technique used to acknowledge each of the individual MPDUs when using aggregate MPDU. |
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Term
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Definition
| A single radio and all of its supporting architecture including mixers, amplifiers and analog/digital converters |
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Term
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Definition
| An 802.11n mode that is not compatible with legacy 802.11a/b/g radios; only HT radios can communicate when using the HT Greenfield |
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Term
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Definition
| A period of time between OFDM symbols that accommodates for late arrival of symbols over longer paths. |
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Term
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Definition
| High Throughput (HT) provides PHY and MAC enhancements to support wireless throughput of 100 Mbps and greater. HT is defined by the 802.11n draft amendment for clause 20 radios. |
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Term
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Definition
| Combining multiple frames into a single frame transmission |
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Term
| Modulation coding scheme (MCS) |
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Definition
| As mandated by 802.11n draft amendment, data rates for clause 20 HT radios are defined by multiple variables known as MCS. Non-HT radios that used OFDM technology (802.11a/g) defined data rates of 6 Mbps-54 Mbps based on the modulation that was used. HT radios, however, define data rates based on numerous factors including modulation, the number of spatial streams, channel size, and guard interval. |
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Term
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Definition
| Four protection modes used by 802.11n to ensure backward compatibility with older 802.11 a/b/g radios |
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Term
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Definition
| In a MIMO system, multiple spatial streams are sent with the same (equal) modulation |
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Term
| Aggregate MAC Service Data Unit (A-MSDU) |
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Definition
| A frame aggregation technique that combines multiple frames into a single frame transmission. The aggregated MSDUs will have a single destination when wrapped together in a single frame. Multiple MSDUs are encrypted by using the same dynamic encryption key. |
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Term
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Definition
| The 802.11n amendment defines an operational mechanism that accounts for coexistence between 802.11n HT coverage cells and nearby legacy 802.11a/b/g coverage cells. When either an HT or non-HT station transmits a frame, the station first sends a request-to-send(RTS) frame to the HT AP.The AP will then reply with two clear-to-send (CTS) frames. One CTS frame is in the legacy non-HT format, while the other frame is in the HT format |
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Term
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Definition
| This occurs in 802.11n when a transmitter and receiver work together to educate each other about the characteristics of the MIMO channel. The transmitter will make phase adjustments based on the information that is returned from the receiver. When using explicit feedback, the beamformee makes a direct estimate of the channel from training symbols sent to the beamformee by the beamformer. The beamformee takes that information and sends additional feedback to the beamformer. The beamformer then transmits based on the feedback from the beamformee. |
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Term
| Aggregate MAC Protocol Data Unit (A-MPDU) |
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Definition
| A frame aggregation technique that combines multiple frames into a single frame transmission. All of the 802.11 frames (MPDUs) do not have to have the same destination address. Also, the data payload of each MPDU is encrypted separately by using the multiple dynamic encryption keys that are unique between the AP and each individual client |
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Term
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Definition
| A public location where wireless data services are available |
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Term
| Wireless Communications Allow? |
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Definition
| Surfing the internet at public locations via HOTSPOTS... public locations where wireless data services are available. |
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