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B Access Point Coverage

This subtopic describes the coverage of access points.

1-Mbps DSSS

1-Mbps DSSS

2-Mbps DSSS

5.5-Mbps DSSS

11-Mbps DSSS

Greater range for lower data rates

WLAN clients have the ability to shift data rates while moving. This technique allows the same client operating at 11 Mbps to shift to 5.5 Mbps, 2 Mbps, and finally still communicate in the outside ring at 1 Mbps. This rate shifting happens without losing the connection and without any interaction from the user.

Rate shifting also happens on a transmission-by-transmission basis; therefore, the access point has the ability to support multiple clients at multiple speeds, depending upon the location of each client.

■ Higher data rates require stronger signals at the receiver. Therefore, lower data rates have a greater range.

■ Wireless clients always try to communicate with the highest possible data rate.

■ The client will reduce the data rate only if transmission errors and transmission retries occur.

This approach provides the highest total throughput within the wireless cell.

6-44 Building Cisco Multilayer Switched Networks (BCMSN) v3.0

© 2006 Cisco Systems, Inc.

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