From what I've read of Frame Utilization and the Overload counter(and please correct me if I'm wrong) the frame utilization metric tells me how much of my up/down frame period I'm using to send packets, and the overload counter is how many packets were rebroadcasted due to various reasons (ethernet in/out, rf in/out).
That being said, would anyone care to share their thoughts regarding using frame utilization, overload, and throughput to determine the overall percentage of capacity.
For example: I've had AP's with 8 customers on it, running almost 100% frame utilization, very low overload counts, and between 15Mbps - 20Mbps (2.4GHz PMP450); and by using the standard "frame utilization = percentage of capacity" I would say this AP is "full"; however, because of the low overloads, as well as the low throughput, I would say that we could safely put more customers onto this AP.
So, where is the delicate balance that determines whether that AP is at capacity? How many Overload Packets is a reasonable ammount? Should the only metric for "capacity" be flat out Current Throughput vs. Calculated Throughput?
As Juan pointed out, you should be looking at Frame Utilization stats. If frame utilization stats are above 90% or closer to 100% that means you are maximizing data capacity of the sector you’re monitoring at the specific time (peak hours).
There are few things you can check or do to improve this. Identify if there are any SMs in the sector that are running at low modulations. SMs at low modulations will take down the entire sector capacity. Adding a dish (to improve signal levels and modulations) or realigning these SMs is one option.
Second option will be to see if you can use a wider channel. However since you are running in 2.4 GHz it will be difficult to find a wider channel.
Third option will be to adjust the Downlink percentage. If you are running 75% at the moment you can try to increase to 80%. Please note this will affect the Synchronization among the APs on the tower in case you are using ABAB deployment scenario.