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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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| It is a measurement of the ratio between two powers. Equals 10 * log10(P1/P2) |
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| A unit of power equal to 1/1000 of a watt |
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Term
| received signal strength indicator (RSSI) |
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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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| A point source that radiates signal equally in all directions |
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| 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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| height, force, or power of a wave |
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| 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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| 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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| 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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| Federal Communications Commission (FCC) |
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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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Definition
| The manipulation of a signal so that the receiving station has a way of distinguishing 0s and 1s |
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Definition
| When an access point has two antennas and receivers functioning together to minimize the negative effects of multipath |
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Term
| highly-directional antenna |
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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 |
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Term
| omni-directional antenna |
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Definition
| type of antenna that radiates RF signals in all directions |
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| multiple input multiple output (MIMO) |
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Definition
| Any RF communications system that has multiple antennas at both ends of the communications link and being used concurrently |
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Definition
| When light travels from one point to another, it travels across what is perceived to be an unobstructed straight line |
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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
| Wired Equivalent Privacy (WEP) |
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Definition
| A layer 2 encryption method that uses the RC4 streaming cipher |
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Term
| Temporal Key Integrity Protocol (TKIP) |
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Definition
| An enhancement of WEP encryption that addresses many of the know weaknesses of WEP. |
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Term
| Orthogonal Frequency Division Multiplexing (OFDM) |
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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 |
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Term
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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 |
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Term
| Advanced Encryption Standard |
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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 |
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Definition
| Verification of user identity and credentials |
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| 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 |
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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 |
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Definition
| The movement or motion of the RF waves through the air |
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Term
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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 |
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Definition
| The level of background noise |
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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 |
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Term
| Service Set Identifier (SSID) |
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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 |
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Term
| Basic Service Area (BSA) |
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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 |
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Term
| Basic Service Set (BSS) |
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Definition
| Involves communication between a single AP and client station that are associated to the AP. |
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Term
| Basic Service Set Identifier (BSSID) |
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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 |
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Definition
| Media access control method used by 802.11 networks |
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Term
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Definition
| A wireless network configuration that connects only two devices together. This is typically a wireless bridge link. |
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Term
| Point-to Multipoint (PtMP) |
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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
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Definition
| WLAN controllers are used in a centralized WLAN architecture together with lightweight AP's, known as thin APs. |
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Term
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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 |
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Term
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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
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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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| Authorization, Authentication and Accounting (AAA) |
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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
| Internet Protocol Secuirty (IPsec) |
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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 authentication. |
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Term
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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. |
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Term
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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
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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 |
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