Cisco Systems OL-1744-02 Parts of the Client Adapter

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Cisco Aironet Wireless LAN Adapters Installation and Configuration Guide for MS-DOS

OL-1744-02

Chapter 1 Overview Parts of the Cli en t Adapter

Throughout this document , t he s e t er ms are used:

•client adapter—Refers to all three type s of adap ters

•PC card, LM card, or PCI cl ie nt ad ap te r—Refers only to a spec ific ad ap ter

•workstation (or station)—Refers to a computing device with an i n stal led c li ent ad ap t er

•End Node—A client node that is located at the end of the Network Tree.

•Infrastructure—The wirel ess i nfrastructure is the commu n ica ti ons system that combines acc ess

points, mobile nodes, and fixed nodes. Access points within the infrastructure can be either root

units, which are physic all y wi red to the LAN backbone, or ca n act as wi reless repeaters. Other R F

enabled devices serve as fixed nodes or mobile client nodes.

•Parent/Child Node—Refers to the relationships between nodes in the wireless infrastructure. The

complete set of relatio nships is sometimes desc ribed as a network tree. Fo r example, the access point

(at the top of the tree) would be the parent of the end nodes. Conversely, the end nodes would be the

children of the access p oint .

•Power Saving Protocol (PSP) and Non-Power Saving Protocol—The Power Saving Protocol allows

computers (usually port ab le c om puters) to power up only par t of t he ti me to conserve energy. If a

client node is using the Power Saving Protocol to communicate with the network, the access point

must be aware of this mode an d im p le men t additional features such a s message store and forwar d .

If the client node is powered from an AC line, do not use PSP.

•Repeater—A repeater is an acce ss point that extends the radio rang e of the infrastructure. A repea ter

is not physically attached to the wired LAN, but communicates through radio to another access

point, which is either a root unit or another repeater.

•Root Unit—The root unit is a n access point that is located at the top, or starti ng point, of a wireless

infrastructure. A root unit provides the physical connection to the wired LAN and contains

configuration information in its association table th at covers all nodes that access the wired network

(backbone). All access po ints di re ctl y att ach ed t o th e w i re d LA N b ack bon e a re root units.

Parts of the Client Adapter

The client adapter is com po s ed o f th r ee m ajor parts: a radio, a rad io an t enna, and two LEDs.

The client adapter contains a direct-sequence spread spectrum (DSSS) radio that operates in the 2.4-GHz

license-free Industrial S cientific Medical (ISM) band. The radio transmits dat a over a half-duplex radio

channel operating at up to 11 Mbps.

DSSS technology causes radio signals to be transmitted over a wide frequency range, using multiple

frequencies simultaneously. The benefit of this technology is its ability to protect the data transmission

from interference. For e x amp le, if a pa rt icu lar f re quency encounters noise, in terf er en ce, or bot h, enoug h

redundancy is built into the sign al on other frequencies tha t the client adapter usually is successful in its

transmission.