Installation guide

Understanding Beamforming  ClientLink 1.0 and 2.0
ClientLink 1.0 was first introduced with the AP 1250 and AP 1140 series. It is a method of creating a stronger
signal on the downlink side for 802.11a/g clients by hearing the clients on the uplink, then adjusting the
transmitter timing so the signal appears much stronger at the client end.
This feature used to be user configurable. However, starting with 7.2 code stream it is now on by default and
is not user configurable because there is no benefit to disabling it.
The AP 3600 fully supports ClientLink 1.0 for 802.11a/g clients but has a greater advantage because it also
supports all 802.11n clients including 1, 2 and 3 spatial stream clients. This capability is called ClientLink 2.0.
There is a distinct advantage with ClientLink 2.0 over the 802.11n enhanced beamforming specification.
ClientLink 2.0 works with all clients today and does not require any client sounding or support (Figure 33).
Figure 33  ClientLink 2.0
With beamforming technology, changing the timing of two transmitters creates a stronger signal for the
receiver, for example, a client device. This is referred to as constructive interference. Sometimes, the opposite
happens and the signals cancel each other out. This is called destructive interference. See figure 34.
Figure 34  Beamforming (constructive and destructive interference)