WiFoo..The.Secrets.of.Wireless.Hacking [Electronic resources] نسخه متنی

C

captured antenna

A wireless device that contains a nonremovable antenna.

Card Bus

A 32-bit interface standard for PC card devices. Similar form factor to PCMCIA, and typically provides support for older 16-bit PCMCIA PC cards.

carrier frequency

The base frequency of a transmitted signal that would be transmitted if it were not modulated by information. A carrier "frequency" can be either a single frequency or a range of frequencies carried at one time between the transmitter and receiver.

CCA

Clear Channel Assessment. Wireless devices can be configured to a particular background interference level found in a specific environment, for reduced overhead contention with other wireless systems.

CCK

Complementary Code Keying. A physical layer modulation technique used by the 802.11b standard to achieve 5.5- and 11-Mbps data rates.

CCX

Cisco Compatible Extensions. Provides tested compatibility with licensed Cisco infrastructure innovations.

CDMA

Code-Division Multiple Access. A technique associated with spread-spectrum systems that is used to increase channel capacity. Typically, each user is given a different pseudo-random spreading code. To communicate with a particular user, the sender must select the code assigned to that user. This technique can permit many users to operate simultaneously on the same frequency.

cell

In wireless networking, the coverage area of a single wireless AP or wireless bridge. This is also known as the basic service area (BSA).

chip

In spread spectrum, the time it takes to transmit a bit or single symbol of a pseudo-random noise (PN) code (a single element of the spreading code).

coaxial cable (coax)

A concentric two-conductor cable in which one conductor surrounds the other, separated by an insulator.

coax seal

A type of moldable plastic that is used for weatherproofing and sealing radio connectors.

collision domains

A collision domain is where one or more devices are connected to a single network, and only one device on that network may transmit at a time. Often referred to as an Ethernet segment.

collisions

In network systems, when two nodes transmit simultaneously, causing destruction of a data packet's information.

compression

In RF amplification, an amplifier is said to be "in compression" (distorting) when the output is no longer a linear representation of the input signal, typically at the operational limits of the amplifier.

CSMA/CD

carrier sense multiple access/collision detection. The LAN access method used in Ethernet. When a device wants to gain access to the network, it checks to see whether the network is free. If it is not, it waits a random amount of time before retrying. If the network is free and two devices access the line at exactly the same time, their signals collide. When the collision is detected, they both back off and each waits a random amount of time before retrying.

CTS

clear to send. A signal or frame of data indicating that the receiver has "permission" to send data. In 802.11 WLANs, a device sends a CTS control packet to indicate to the WLAN network a data packet is about to be sent.

CW

continuous wave. An analog signal that is always "on" (100 percent duty cycle).