802.11K

In extreme networks Identifi solution, 802.11K can be enabled on advanced tab of WLAN service.

If it is enabled, then AP shows nearby AP information with bssid, channel, RSSI information.

The goal of the 802.11 Task Group k (TGk) is to provide a means of radio resource measurement.

The draft amendment calls for measurable Physical layer 1 and MAC sublayer of the Data-Link layer 2 client statistical information in the form of requests and reports. 802.11k defines mechanisms in which client station resource data is gathered and processed by an access point or WLAN switch.

Think of a WLAN switch as a central controller that manages many access points. In some instances, the client may also request information from an access point or WLAN switch.The following are some of the key resource measurements defined under 802.11k:

Transmit power control (TPC) The 802.11h amendment defined the use of TPC for the 5 GHz band in Europe to reduce interference. Under 802.11k, transmit power control will also be used in other frequency bands and in areas governed by other regulatory agencies.Client statistics Physical layer information such as signal-to-noise ratio, signal strength, and data rates can all be reported back to the access point or WLAN switch. MAC information such as frame transmissions, retries, and errors may all be reported back to the access point or WLAN switch as well.

Channel statistics Clients may assemble noise floor information based on any RF energy in the background of the channel and report back to the access point. Channel load information may also be collected and sent to the AP. The access point or WLAN switch may use this information for channel management decisions.

Roaming site reports Mobile Assisted Hand-Over (MAHO) is a technique used by digital phones and cellular systems working together to provide better handover between cells. 802.11k gives access points or WLAN switches the ability to direct stations to perform the sort of tasks that a cellular network requires its handhelds to do when using Mobile Assisted Hand-Over.

Using proprietary methods, client stations keep a table of “known access points” and make decisions on when to roam to another access point. As defined by 802.11k, the access point or WLAN switch will request a station to listen for access points on other channels and gather information. The current AP or WLAN switch will then process that information and generate a “site report” detailing available access points from best to worst. Before a station roams, it will request the site report from the current AP and then roam to the best access point on the site report. The 802.11k draft in conjunction with the 802.11r “fast roaming” draft have the potential to greatly improve roaming performance in 802.11 wireless networks.