Белая книга для Cisco Cisco Aironet 3700i Access Point

 

 

© 2015 Cisco and/or its affiliates. All rights reserved. This document is Cisco Public Information. 

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In the downlink direction, the extra transmitter allows for beamforming to the client. This can be thought of as 

analogous to increasing transmit power. But a better description is that the scheme to fully exploit the four MIMO 

transmit chains combines beamforming with spatial multiplexing to improve the speed and reliability of downlink 

traffic. 

Taken together, these improvements mean that 1300 Mbps can be achieved at twice the distance of existing 

solutions - for example, 30 feet instead of 15 feet. This doubling in range actually results in a 500 percent increase 

in the coverage area that can achieve 1300 Mbps. Furthermore, as will be shown in the next section, it results in a 
very consistent, “dead zone free” zone of coverage. 

ClientLink 3.0 Benefits 

The benefits of ClientLink 3.0 are twofold. The proof of the benefits can be seen in Figure 1, which shows the rate 

at different ranges for a competitive access point. As the figure shows, with a 3x3:3 client sending and receiving to 

a 3x3:3 access point, 1300 Mbps can be achieved only at short distances from the access point. 

On the other hand, by adding a fourth receive chain at the access point, 1300 Mbps becomes usable out to 30 feet. 

This behavior is well matched to the expected coverage range of access points in typical enterprise deployments. 

Next, all four transmit chains are used, even when the number of spatial streams is less than four. This results in 

some gain on the signal level due to more transmit power. Also, sending each stream from all four transmit chains 

collectively results in significant diversity gain (one stream will not be completely wiped out if one or two antennas 

are in a deep fade). 

As Figure 1 shows, the result is evident in the improvement to the achieved data rate at range, which also 

correlates closely with the reliability of each rate at that range. Assuming a typical enterprise environment, and at a 
typical enterprise range of 30 feet, a 4x4:3 architecture operates at 1300 Mbps, whereas 3x3:3 can’t do better than 

850 Mbps. 

Figure 1.    Coverage Comparison of the Cisco Aironet 3700 Series with ClientLink 3.0 to a Competitive Access Point 

(3ss - 256-QAM)