[Make-wifi-fast] CTS protection

[Pete Heist <peteheist@gmail.com>]

Does anyone know how to disable CTS protection in LEDE (rc2)?

I’ve been running into problems in my testing on the OM2P-HS/LEDE where throughput suddenly drops from ~90Mbps to ~60Mbps, and rrul latency skyrockets, even though the signal and MCS level stay the same. I narrowed this down to the bss flag CTS-protection:

# iperf3 throughput: ~90 Mbps
root@om1:~# iw dev wlan0 link
Connected to ac:86:74:26:aa:aa (on wlan0)
	...
	signal: -46 dBm
	tx bitrate: 144.4 MBit/s MCS 15 short GI
	bss flags:	short-preamble short-slot-time
	...

# iperf3 throughput drops to ~60 Mbps
root@om1:~# iw dev wlan0 link
Connected to ac:86:74:26:aa:aa (on wlan0)
	…
	signal: -46 dBm
	tx bitrate: 144.4 MBit/s MCS 15 short GI
	bss flags:	CTS-protection short-preamble short-slot-time
	...

The flag seems to flip on and off when making tiny changes to router placement, or sometimes seemingly randomly. I suspect it may be because of a distant network also on Channel 1 (scan shows it has a signal of -88), because I seem to be avoiding it for now by swapping with my home network and moving to Channel 6. Maybe those tiny router placement changes were making the distant network either visible or not to the router.

So I’d be glad if I could just manually disable CTS protection, when I know I’ve only got a point-to-point connection and any other networks on the same channel are rather distant.

Also, I suppose this is another example of the difficulty of fixed rate limiting, particularly on crowded frequencies.

Pete