Linksys WCF12 User Guide - Page 17

Instant WirelessTM Series Appendix B: Glossary Ad-hoc Network - An ad-hoc network is a group of computers, each with a wireless adapter, connected as an independent 802.11 wireless LAN. Ad-hoc wireless computers operate on a peer-to-peer basis, communicating directly with each other without the use of an access point. Ad-hoc mode is also referred to as an Independent Basic Service Set (IBSS) or as peer-to-peer mode, and is useful at a departmental scale or SOHO operation. Backbone - The part of a network that connects most of the systems and networks together and handles the most data. Bandwidth - The transmission capacity of a given facility, in terms of how much data the facility can transmit in a fixed amount of time; expressed in bits per second (bps). Bit - A binary digit. The value-0 or 1-used in the binary numbering system. Also, the smallest form of data. BSS (Basic Service Set) - An infrastructure network connecting wireless devices to a wired network using a single access point. CompactFlash - A flash memory format card that plugs into a CompactFlash socket or into a standard Type II PC Card slot with an adapter. CRC (Cyclic Redundancy Checking) - Technique used to check for errors in data transmissions. 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 if the network is quiet (senses the carrier). If it is not, it waits a random amount of time before retrying. If the network is quiet 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 wait a random amount of time before retrying. CTS (Clear To Send) - An RS-232 signal sent from the receiving station to the transmitting station that indicates it is ready to accept data. Database - A database is a collection of data that is organized so that its contents can easily be accessed, managed, and updated. 28 Wireless CompactFlash Card Default Gateway - The routing device used to forward all traffic that is not addressed to a station within the local subnet. Driver - A software module that provides an interface between a network interface card and the upper-layer protocol software running in the computer. DSSS (Direct Sequence Spread Spectrum) - DSSS generates a redundant bit pattern for all data transmitted. This bit pattern is called a chip (or chipping code). Even if one or more bits in the chip are damaged during transmission, statistical techniques embedded in the receiver can recover the original data without the need for retransmission. To an unintended receiver, DSSS appears as low power wideband noise and is rejected (ignored) by most narrowband receivers. However, to an intended receiver (i.e., another wireless LAN endpoint), the DSSS signal is recognized as the only valid signal, and interference is inherently rejected (ignored). Encryption - A security method that applies a specific algorithm to data in order to alter the data's appearance and prevent other devices from reading the information. ESS (Extended Service Set) - A set of more than two or more BSSs (multiple access points) forming a single network. Ethernet - IEEE standard network protocol that specifies how data is placed on and retrieved from a common transmission medium. Having a transfer rate of 10 Mbps., this forms the underlying transport vehicle used by several upperlevel protocols. FHSS (Frequency Hopping Spread Spectrum) - FHSS continuously changes (hops) the carrier frequency of a conventional carrier several times per second according to a pseudo-random set of channels. Because a fixed frequency is not used, and only the transmitter and receiver know the hop patterns, interception of FHSS is extremely difficult. Firmware - Code that is written onto read-only memory (ROM) or programmable read-only memory (PROM). Once firmware has been written onto the ROM or PROM, it is retained even when the device is turned off. Fragmentation - Breaking a packet into smaller units when transmitting over a network medium that cannot support the original size of the packet. 29