The objective of the RF Health Metric is to simplify troubleshooting, and open the possibility to have “automated system” to quickly detect or easily point to bad areas

Basically, try to answer “where in my 100s Aps should I look first”

Main objectives

RF Health is a value from 0 to 100 to represent a simple to understand metric with the RF quality state of AP radio.

0% is dead, 100% if fully healthy
Each different RF metric has its own health score on 0-100 scale

It is easier to understand a 0-100 scale, compared on how difficult to understand would be “a possible cochannel interference on RSSI -47 with 20 clients attached”, or an open scale metric of “ health is

The idea is to translate either by simple correlation or by algorithm mapping, different RF metrics into multiple simple metrics of 0-100 values.

Worst metric selection: Current proposal is to force the “top level” AP health to be the lowest of all individual RF metrics, instead of averaging. Different summarization mechanisms could be implemented based on deployment type (i.e. on high density I would care more on co-channel/noise/client count, on high speed deployment, I would care more on low client SNR, co-channel interferer)

RF health can be summarized per working  group unit:

WLC -> Band 2.4/5 ->AP group or Flex group ->AP

in other tools different summarizations could be used (floor, AP neighborhood, etc)

The summarization level resulting RF health is not average of the previous level, as it would hide several bad scenarios (0 + 100=50), but marked as good/medium/bad, based on which percentage of elements are on good health, etc (i.e. if a third of elements are on <40%, it is marked as bad)

RF Health would represent the “easy to understand”  0-100 metrics, but the raw data would be available through an “RF Stats” view, covering the same summarization levels. The Health part is for the common admin/user, quick to be looked at, easy to understand, and the stats view would be useful for troubleshooting/low level analysis

The health portion would direct you to the stat options if needed

List of proposed health indicators

Note :  this covers  a simplification for 20MHZ channel width case scenario.  There are some rules/ideas for 40/80 cases, but  they are not part of the current document

The current list shows what is available in WLCCA 4.1

Neighbor Channel Capacity (Channel utilization)

This gets a list of Aps operating on the same channel as current evaluated AP, and puts a weight on each one, adding a metric based on the neighbor current channel utilization vs the “distance” the AP is (nearby data)

It correlates nearby Aps vs their activity affecting current AP

Objective is that Aps which are closer to current AP ( higher RSSI) with a higher channel utilization, will have a larger impact on RF health

Pseudo code

For each AP1, obtain list of neighbors on same channel:

Convert received power to a 0 to 100 scale (100% impact is -44 and higher, 0%  impact is -70 and lower)
Get Neighbor AP channel utilization, convert to 0 to 100 scale (0 is 0% impact, 60 is 100% impact)

Neighbor Cochannel utilization health = 100  (converted channel utilization * compensated received power)

                              Pick the lowest level

Neighbor Cochannel  interference/ AP Overlap

This gets the list of nearby Aps on the current channel, and correlates their current operating power (TPC) vs their current RF distance (nearby data)

It creates a relation of  nearby Aps vs their operating power  on how much overlapping they have on the current operating channel of the evaluated AP

Objective is to represent that Aps which are closer to current AP ( higher RSSI) with a higher operating power, will have a larger impact on RF health, independently of their current TX utilization

it is accumulative impact for all APS on same channel as the evaluated AP

Pseudo code

Neighbor Cochannel interference health=100
For each AP1, obtain list of neighbors on same channel:

Convert received power to a 0 to 100 scale (100% impact is -44 and higher, 0%  impact is -70 and lower)
Get Neighbor AP channel currently operating power, correlate using 100 if AP is using power level 1 (max), and 0 if AP is using power level 7 (min, 7 or lower)

Neighbor Cochannel interference health -= (converted power level * compensated received power )

Noise side channel

This metric will correlate a detected noise impact to the current operating channel, vs the “channel distance” where the noise was detected

It has 2 different operational modes:

In 2.4 case:

We need to assign a lowering impact depending on where the channel distance were noise is seen. Same channel is 100% impact, next channel is 80, then 40%, etc

I.e. if AP is on channel 1, noise in channel 5 impact is lowered as 20% impact

Then the noise measurement is converted into a 0 to 100 scale (compensated noise).  Noise below -95 dBm is considered 0 impact, noise above -65 dBm is 100% impact

        The RF health for Side channel noise will be 100- compensated (0-100 scale) of the noise power * channel distance

In 5.0 case:

        if noise is on a side channel (i.e. AP is on 100, noise is on 104), we subtract 36 from the detected noise power level (this is based on channel mask averaging for 11a operation. Static value obtained as a “good enough simplification”)

Same noise power conversion to 0-100 scale

Noise same channel

Extension of the previous procedure. Noise measurement is converted into a 0 to 100 scale (compensated noise).  Noise below -95 dBm is considered 0 impact, noise above -65 dBm is 100% impact

No “side channel” subtraction is done, so this is basically direct conversion of received noise power level to a 0-100 scale based on the above parameters

Interference same channel

Similar to noise correlation, but applied to other wifi activity on the channel.  The range is different, as normally Aps can coexist with Interference (wifi activity) better than with random noise

A value of -50 is considered 100% full impact, -100 is considered 0% impact

Interference has a value of “time” percentage in RRM metrics.  We convert anything higher than 30% time as full impact (100%),

Interference side channel

Similar to noise correlation.  The range is different, as normally Aps can coexist with Interference (wifi activity) better than with random noise

A value of -50 is considered 100% full impact, -100 is considered 0% impact

Interference has a value of “time” percentage in RRM metrics.  We convert anything higher than 30% time as full impact (100%),

Low SNR clients
Objective is to convert  clients connected on bad SNR levels (<20dBm) to a 0 to 100 scale
Aps that continuously have a high count of low SNR clients will either indicate a radio problems on the nearby Aps (causing Aps to roam/use this one) , a coverage problem (bad deployment) or a client roam bug (sticky client)
it is not evaluated for AP with less than 5 clients

Pseudo code:

If AP has >5 clients, then count how many clients are on low SNR (<20), count how many total clients on radio

RF health for low SNR is 100 minus the percentage of clients on  low SNR

Clean air devices (PDA)
Target here is to convert non-wifi detected devices to a 0-100 scale

We should take list of devices, correlate : duty cycle  (0-100), and detected power level (below -80 ignore/0%  impact,  above -65 is 100%)

RF Health PDA would be 100 – (Correlate power *  duty cycle),

Radio utilization

This is direct translation of the radio utilization. If correlated the AP scale, using 0 as no impact, 70 as full impact

So, AP on 35% radio utilization would rate as RF health Radio Utilization of 50%

Clean Air quality (if applicable)

Directly use air quality as  indicator (it is already in 0-100 scale)

Metrics being evaluated for next releases

“Isolated Aps”: report Aps that have neighbours all on very low values, do not calculate for Aps with zero neighbours both in TX and RX path. (assuming standalone devices).