First, some back of the envelope theoretical calculations to check that you are not running into theoretical capacity limits.
Estimation of traffic (per second) - Assumptions
- All data activity occurs over a 40-hour week
- Data usage is evenly spread across the 6 APs
- The available data rate of a standard AP is generally considered to be 40% of nominal throughput under benign operational conditions
- To allow for operational overheads, a 20% network overhead is assumed, so conversions from Bytes to bits is done on an overhead adjusted basis (10-bits per Byte)
AP Capacity
- Per AP Nominal rate 1.3 Gbps
- Per AP Available rate 0.52 Gbps
- 6 AP Total Capacity 3.12 Gbps
Wireless Data Usage
- 6 APs -Aggregate per week 430 GB
- Average usage per second per AP 52Mbps
Explanation of units used
- Gbps Gigabits per second
- GB Gigabytes
- Mbps Megabits per second
- 8 bits (b) = 1 byte (B)
Because of packet overheads inherent in the OSI model, which different manufacturers include/exclude from their explanations of how packet sizes are calculated (different CISCO products do not always calculate this the same way), and the seldom discussed overheads created by error-correction techniques, a rough rule of thumb when calculating the number of bits to transmit over a link is to multiply the bytes by 10, rather than the 8 than is the actual conversion figure.
The good news is that, in aggregate, you have plenty of spare capacity.
Unfortunately, the real world doesn’t deal in averages, users judge the adequacy or otherwise of a network by the worst-case experience.
Virtually anything to do with networks tends to have its bursty moments. At the start of the day, before and after the mid-day break, and before leaving at the end of the day, are all times when there is atendency for users to be active concurrently.
Few users watch youtube all day, but if something is going viral, peak usage may be many times greater than a few minutes earlier. And users will complain if the system can't take this in its stride.
The best handle you can get on the peaky nature of your WiFi traffic is found on the dashboard pages for the individual APs. Select an AP from the list and scroll down the detail page and you will see graphs showing live traffic on the uplink, and further down the page, usage. Both graphs show usage in bits per second. Along with the list of Access Points, these will show which of the APs has the most users, the greatest data volumes and how the various 2.4 and 5 GHz networks are configured, in terms of channel width and available capacity.
Wireless networks perform best when the hardware is not swamped by transient peaks. Particularly in the 5 GHz portion of the radio spectrum, having more APs operating at lower transmit power is preferable to fewer APs at maximum power. The devices they communicate with have much lower powered radios. For a WiFi link to be initiated and maintained both host (client device) and AP must be able to communicate with each other, it isn’t like broadcasting.
Because there are more non-overlapping channels available in the 5 GHz band than the 2.4 GHz band, and 5 GHz signals have roughly half the propensity to propagate as those of the (Usually over-crowded) 2.4 GHz band, we can eliminate gaps in coverage by placing additional 5 GHz APs, without diminishing overall throughput. Don’t worry about having more APs than you think you need, if properly set up, it will cause less management issues and greater user satisfaction.
I don’t have specific data on how many users different AP models can handle in different scenaria, it would be interesting to hear from some of the school network administrators as classes tend to do quite a lot in unison, so it gets very bursty. I did discover that half a dozen kids on a sleep over equipped with tablets and phones hoovered up the bandwidth watching videos aqnd chatting about it.
If any specific APs are getting overloaded, then there is quite a lot that can be done as far as network tuning and user management is concerned, but the hows and whys of that are for another day.