What is best practise on setting data rates and basic rates for fine tuning links.
Most users set Rate set to default on both AP and station and let ROS look for the best rates.
On links with issues like long distances (low signal), interferences and/r high noise levels or otherwise issue this might need more fine tuning.
First we need to understand that AP depicts, but never can set higher rates than station would have set if not default.
Second, I have been told that everytime AP steps a link down or up in connected rate the radio's can't communicate for a split second and packages get lost which deteriorate link quality. So it is better to set links manually to best achievable stable connection rate.
Supported versus basic rates if we use the configured options:
Some use all available rates but just disable the highest ones if the link can't maintain the highest rates.
Some set all available supported rates to the highest possible but set basic only to the lowest
Some set only some supported rates, or only one that can be achieved and kept stable, while basic is still only set on lowest.
Some set only some supported rates, or only one, and set the basic to the same.
I recently set both my supported rates as well as the basic to one rate only, the highest all stations can keep without disconnects. I look at the CCQ level to achieve this. I'd like to see near 100%
But, I need better understanding on what exactly is the basic rate needed for?
I have several AP-radio's where I set the supported rate same as basic rate, for instance 24Mbps and I got a nice link statistics for such links. Near 100% CCQ all the time, even for stations that would switch back to lower levels that in default setup would drop back to lower rates.
Recently I have been adviced by MT to set the basic rate to the lowest available rate.
In doing so it means at least same rate has to be set in ´supported´ as well.
The result was that now most of my links show this lowest rate as the rate the link connects to, and only when considerable amount of traffic is running over these links the rate jumps to the higher set rate.
In the mean time the CCQ falls way back on idle links but even on moderate traffic links the CCQ level never reach the solid high near 100% levels any more. The CCQ became more variable around -95.
I had to tune down the supported rate back to the lowest level to get a rock solid 100% CCQ again!
Off course, running a bandwith test on that last option I get ample 60% of the speed out of this link. Un acceptable for a backhaul if that has to be set to 6Mb on a 10Mhz channel width freq. (802.11a).
Set the link back at a fixed 24Mb for supported and only 6Mb for basic I get my higher throughput back again but CCQ never stabilizes at the near 100% range any more.
Set the link back at a fixed 24Mb for both supported and basic rate than my higher througput is still there combined with near 100% CCQ.
But now I am in a situation that links sometimes drop, even although the signal levels are around -50 and noise levels are better than 30dB! (Because of this MT gave me the advice to drop basic back to lowert level)
I need a good advice on why, and when, higher then the lowest basic rates can be used, in combination with what highest supported rates are stabily achievable.
Last, but not least: In case of an AP with many clients.
If some client stations can connect at 48 or 52Mbps but others only at much lower rates. What is best to do here? Set rates at default so AP everytime can find best rate for connection to certain station?
Or set rates to accomodate worst station with a stable connection. If this is only 12Mbps than it is 12Mbps for all units! (In this case the maximum data througput for a strong signal client depends on that one from the bad signal client. Not something I'd like...)
Please add your thoughts here so all users can benefit and learn about the working of wifi!
MT manual is not always very clear in what is best practise....