I thought that RTS/CTS would handle the case of hidden nodes, i.e. a device that fails to successfully transmit can resort to RTS/CTS to get the receiver to reserve time for it. Also, lack of a RX ack seems ok to trigger MAC level retransmits.

It seems the LBT bug is the collision avoidance overheads when it isn't needed, i.e. no other energy would cause the RX PHY to fail its decode and the EDCA backoffs had no benefit, stochastic or otherwise. Optimizing that out is said to be not possible from local information only and per "shared" spectrum.

Bob

On Mon, Aug 27, 2018 at 3:33 PM David Lang <david@lang.hm> wrote:

On Mon, 27 Aug 2018, Jonathan Morton wrote:

> So in practice, it's easier to measure SNR at the receiver, or indirectly by
> observing packet loss by dint of missing acknowledgements returned to the
> transmitter.

Also, there may be other transmitters that the recipient of the packets can hear
that you cannot hear, so it's not possible to detect colliding transmissions
directly in all cases.

This is another trap that digital/wired people fall into that doesn't really
apply in the analog/radio world.

David Lang