Cisco Cisco Aironet 1140 Access Point Libro blanco

White Paper

Page 4 of 6

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Compute the weights on each received packet based on the MRC algorithm

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Store the weights for each client

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Look up the weights for the appropriate client prior to transmission

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Apply the weights to the transmitted signal, forming a radio beam

Because these enhancements are made in hardware, there is minimal additional overhead on the access point’s

platform and therefore no performance loss due to the signal processing.

The ClientLink algorithms deliver an optimum reinforced signal to the client on its one antenna (Figure 3). And

because this technology does not depend on any client-side hardware or software capabilities, it works with all

existing 802.11a/g clients. (Note that ClientLink interoperates seamlessly in mixed mode environments where

802.11n and 802.11a/g clients co-exist on the same access point. For 802.11a/g clients, transmit beam forming is

used to increase the gain towards the client. For 802.11n clients, spatial multiplexing is used to deliver enhanced

high throughput data rates upwards of 300 Mbps. In this manner the optimum MIMO technology is dynamically

selected to deliver benefits to each client type.)

Figure 3. Example Alignment of Two transmitted phases to maximize signal at the client (X)

Cisco ClientLink technology effectively enables the access point to optimize the SNR exactly at the position where

the client is placed. Improved SNR yields many benefits, such as a reduced number of retries and higher data rates.

For example, a client at the edge of the cell that might previously have been capable of receiving packets at 12 Mbps

could now receive them at 36 Mbps. Typical measurements of downlink performance with ClientLink show as much

as 25 percent greater throughput for 802.11a/g clients. By allowing the Wi-Fi system to operate at higher data rates

and with fewer retries, ClientLink increases the overall capacity of the system, which means more efficient use of

spectrum resources.