Cisco Systems OL-1744-02 Radio Ranges

1-4

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

OL-1744-02

Chapter1 Overview

Radio Ranges

The type of antenna used depends on your client adapter:

•PC cards have an integrated, permanently attached diversity antenna. The benefit of the diversity

antenna system is improved covera ge. The system works by allowing the ca rd to switch and sample

between its two anten na ports in order to s ele ct the optimum port fo r r ece ivin g da ta packets. As a

result, the card has a bet te r ch an ce o f ma in tai ning the radio frequency (RF ) co n ne cti on i n ar eas o f

interference. The antenn a i s lo ca ted w i th in th e s ect io n of t he ca rd t hat p r ot rud es fr om th e P C c ar d

slot when the card is installed.

•LM cards are shipped without an an tenna; however, an antenna can be connected throu gh the card’s

external connector . If a snap-o n a nten na is use d, it shoul d b e oper ate d in div e rsi ty mo de. Otherwi se ,

the antenna mode used s h ou ld c or r esp on d to t he an te nna port to which the a nt en na is co nn ect ed .

•PCI client adapters are s h ip p ed w it h a 2 - dBi d i pole antenna that attach es t o th e a dapter’s antenna

connector. However, other types of antennas can be used . PCI adapters can be operated on ly through

the antenna port located on the right side of the radio module (not to be confused with the antenna

connector on the card car ri er ).

Note External antennas u sed in combinati on with a power sett ing resulting in a radiated power leve l above

100 mW equivalent isotropic radiated power (EIRP) are not allowed for use within the European

community and other countries that have adopted the European R&TTE directive. CEPT

recommendation Rec 70.03, or both. For more details on legal combinations of power levels and

antennas in those countri es , co nt act C isco C orporate Compliance.

The adapter has two LEDs th at glow or blink to show the status of t he ad ap te r or t o convey error

messages. See “Interpreting the Indicator LEDs” section on page5-2 for an inter p re tation of the LED

codes.

Radio Ranges

Because of differences in component configur ation, pl acem ent, and physi cal environm ent, every

network application is a unique installation. Before installing the system, you should perform a site

survey in order to determine the optimum utilization of networking components and to m aximize range,

coverage, and network performance.

Here are some operating and environmental conditions that you need to consider:

•Data Rates—Sensitivity and range are inversely proportional to data bit rates. The maximum radio

range is achieved at the lowest w or k ab le da ta ra te. There is a decrease in rec e iver th re sho ld

sensitivity as the radio data rate in crease s.

•Antenna Type an d Pl acem ent— Prop er ante nn a con f igura t ion i s a cri tic al f ac tor i n ma xi miz ing ra di o

range. As a general guide, range increases in proportion to antenna height.