[Cake] WiFI/shared media and bursting

[Cake] WiFI/shared media and bursting

[Daniel J Blueman]

Hi Dave, Toke et al,

Given various challenges brought by WiFi (and related radio frequency systems):
1. the maximum throughput varies by media attenuation (eg range) and
device capability, all else aside (ie isolated environment)
2. the upstream and downstream paths share the same media
3. the media is shared with other devices (increasing the noise floor)
and networks cause 802.11 Clear Channel Assessment to defer
transmission

For these reasons any bandwidth estimation (autorate) may be valid
only for 10s of milliseconds.

Therefore for a given density of access point deployment, there should
be a conservative throughput lower bound covering, for example 40Mbps
(peak unidir would be 120Mbps). Since this is shared among upload and
download, one could deploy CAKE with a fixed 20Mbps limit for upload
and 20Mbps for download.

A second approach might be to have a TBF or related scheme to allow
per-stream bursts, limiting them to 15Mbps (or less) steady-state
after a burst period. Though this defeats one aspect of CAKE, I'm
using this approach to attempt to manage latency better. It's worth
noting the Linux drivers I'm using aren't ath10k or such, so do
over-buffer.

Does anyone have any advice or experience on this or another scheme
with WiFi or related?

Thanks,
  Dan
--
Daniel J Blueman