Cisco Aironet 3700 Series Deployment Manual page 45

Figure 61 Example of ClientLink (directing the signal to a client, in this case 1 spatial stream)
In order to beamform to clients using 3 spatial streams, since 3 transmitters are used in the transmissions,
Note
the AP needs at least one additional radio to beamform. The AP 3600 and AP 3700 use 4 radios per band
and can beamform to clients using 3 spatial streams.
To summarize, Cisco ClientLink takes the received signals heard from the client on the uplink, calculates
how the multipath signal looks from those streams, and then on the reciprocal side (transmit downlink)
figures out the optimal way using all four radios to best form the signal (transmit beamforming) to enable
the client to best decode (receive the signal on the downlink) with the least amount of retries.
ClientLink 3.0 with AP 3700 enables beamforming to all 802.11n and 11ac clients, including 3SS
clients. ClientLink 2.0 with AP 3600 enables beamforming to all 802.11n clients, including 3SS clients,
and can do so for up to 128 clients at a time.
AP 1600 supports less clients (32) and does not support 3-ss. ClientLink 1.0 supported a maximum of
Note
15 clients at a time. ClientLink 2.0 significantly improves throughput and coverage of up to 60% on the
downlink side for a much better 802.11n client connectivity and enhancing the Bring Your Own Device
(BYOD) experience.
Cisco Aironet Series 2700/3700 Access Points Deployment Guide
Cisco Aironet Series 3700 Access Point
45