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Client Link (know as beamforming as well) is a spatial-filtering mechanism used at a transmitter to improve the received signal power or signal to noise (SNR) ratio at an intended receiver(client). ClientLink uses multiple transmit antenna to focus transmission in the direction of a 802.11a or 802.11g client ( true for WLC 7.0.116.0 code & later releases with 3600 may support this for n clinets as well- Called ClientLink 2.0) which increases the downlink SNR and the data rate to the client, reduces coverage holes & enhance overall system performance. Below diagram shows graphical representation of effect of client link.
ClientLink starts only when signal from the client falls below these thresholds:
802.11a clients – RSSI of -60 dBm or weaker
802.11g clients – RSSI of -50 dBm or weaker
AP actively maintains ClientLink data for upto 15 clients per radio.
When configuring ClintLink following guideline should followed.
1. ClientLink is supported only for legacy OFDM data rates (6,9,12,18,24,36,48,54 Mbps)
2. Only APs that support 802.11n can use client link
3. Two or more antennas must be enabled for transmission
4. OFDM data rates must be enabled.
Following screen “Wireless -> 802.11b|802.11a ” shows the setting to enable client link.
You can override this and enable or disable it per AP. To do that you have to go to the required AP ” Wireless -> Access Points -> Radios > 802.11a/n or 802.11b/g/n” page. Below shows disabling clinet link for a AP (named LWAP-03)
By using CLI you can enable this as well. see below commands
config 802.11a|802.11b beamforming global enable|disable config 802.11a|802.11b beamforming ap <AP_name> enable|disable
You can verify this by “show 802.11a” or “show ap config 802.11a <ap_name>” CLI commands as shown below.
(WLC1) >show 802.11a . . Beacon Interval.................................. 100 CF Pollable mandatory............................ Disabled CF Poll Request mandatory........................ Disabled CFP Period....................................... 4 CFP Maximum Duration............................. 60 Default Channel.................................. 36 Default Tx Power Level........................... 0 DTPC Status..................................... Enabled Fragmentation Threshold.......................... 2346 TI Threshold..................................... -50 Legacy Tx Beamforming setting.................... Enabled Traffic Stream Metrics Status.................... Disabled Expedited BW Request Status...................... Disabled World Mode....................................... Enabled EDCA profile type................................ optimized-video-voice (WLC2) >show ap config 802.11a LWAP-03 . . Phy OFDM parameters Configuration ............................. AUTOMATIC Current Channel ........................... 40 Extension Channel ......................... NONE Channel Width.............................. 20 Mhz Allowed Channel List....................... 36,40,44,48,52,56,60,64,149,153,157,161,165 TI Threshold .............................. -50 Legacy Tx Beamforming Configuration ....... AUTOMATIC Legacy Tx Beamforming ..................... ENABLED Antenna Type............................... INTERNAL_ANTENNA Internal Antenna Gain (in .5 dBi units).... 8
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Related Posts
1. RRM Basics
2. Configuring RRM
3. Configuring DCA
4. Configuring TPC
5. Configuring CHD
6. Overriding RRM
7.
8. Rogue Access Point Detection
mrn-cciew 
Nowdays even 1600 Series AP is Clientlink 2.0 capable, it pleases me.
But it’s interesting to know how Clientlink works in real life.
As I not use x600 Sereies AP before, can you Rasika please share yours experience with beamforming? This week I’ll speak with our Medical College IT director about new Wi-Fi implementation in their educational buildings and information about real-life experience will be important for him.
Hi Maksim,
I have not deployed 1600/2600 in our environment (only 3600 in that x600 series).
In general I would suggest at least 2600 or 2700 series AP for typical enterprise deployment. If you could afford 3600/3700 it is much better.
Client link in real life, you have to do some testing & verify the difference. But in my case I have not put that much effort to verify those features.
Regards
Rasika
I have a cisco aircap 3602i-e-k9 ap I just acquired, I have tried all the default IPs I know, but could not log in. Please how do I log in to it’s GUI and configure it?
Thanks.
It may not have default IP. You just need to get into CLI access via console cable (Cisco/Cisco) should work if it is brand new access point.
Depend on the software it has (CAP-Lighweight or SAP-Standalone) either it will require a WLC to operate. If it comes with Standalone image you can configure it via GUI or CLI.
HTH
Rasika
Thanks.