I would be very interested in seeing the correlations between set-up time and total devices in the area (or, to be more precise, total channel utilization). This paper studied devices associated per access, point, which is a separate metric. They mentioned the issue in a paragraph at the end of a section, probably dug up in post-study literature review.
From work in wi-fi router development, high channel utilization is often a much bigger determinant of packet loss than either router overload or RSSI. Hour of day is probably just a good proxy for this.
802.11 is pretty good at handling the shared medium when a single access point can do traffic control, but multiple access points in a crowded city or office building gets you into all kinds of problems. Usually you can get big performance gains in large deployments just from making sure nearby access points are on different channels.
Between the other two major factors the paper looked at:
1) The number of clients a single router can handle is mostly limited by CPU power (and the failure mode there is typically not association request drops, since those are usually processed pretty early in the packet pipeline, without much queuing). So I'm not surprised that they saw very little effect of number of associated clients with connection time.
2) RSSI is more important in low-interference environments, where the ability to hear packets over the noise floor is a big limiter. In dense, high-interference environments, it helps a bit in terms of being able to shout over the noise of very distant interference sources, but for the most part a collision is a collision even with substantial magnitude differences between the colliding packets.
Since you work in WiFi, I was wondering if you could comment the linked chart of SNR to Modulation rates [0]. Obviously the exactly values are going to depend on hardware to some degree.
What exactly do you mean by comment? Explanation of what it represents?
Basic overview, with the caveat that I haven't done wifi stuff in a couple of years, and was not doing straight up RF stuff like the hardware folks. It's basically saying that as signal strength above the noise floor (in dB) (ie RSSI - kind of) increases, you can get to higher bit rates. Let me know if you want more info on what exactly is being described.
From work in wi-fi router development, high channel utilization is often a much bigger determinant of packet loss than either router overload or RSSI. Hour of day is probably just a good proxy for this.
802.11 is pretty good at handling the shared medium when a single access point can do traffic control, but multiple access points in a crowded city or office building gets you into all kinds of problems. Usually you can get big performance gains in large deployments just from making sure nearby access points are on different channels.
Between the other two major factors the paper looked at:
1) The number of clients a single router can handle is mostly limited by CPU power (and the failure mode there is typically not association request drops, since those are usually processed pretty early in the packet pipeline, without much queuing). So I'm not surprised that they saw very little effect of number of associated clients with connection time.
2) RSSI is more important in low-interference environments, where the ability to hear packets over the noise floor is a big limiter. In dense, high-interference environments, it helps a bit in terms of being able to shout over the noise of very distant interference sources, but for the most part a collision is a collision even with substantial magnitude differences between the colliding packets.