[rt2x00-users] RTS threshold on rt2800

Helmut Schaa helmut.schaa at googlemail.com
Wed Sep 14 19:41:26 EST 2011


Hi,

I was just playing with RTS threshold values and rt2800pci. Setting
the RTS threshold to 100 bytes for example via:

iw phy phy0 set rts 100

correctly results in RTS/CTS handshakes prior to each transmission.
However, if aggregation comes into play I don't see any RTS/CTS
frames prior to the AMPDU transmission even if it is >100 bytes.

So, it seems that the rt2800 hw applies the configured RTS
threshold only to non-AMPDU transmissions :(

I'd be glad if anyone could verify that on a different rt2800pci (or
rt2800usb) hardware.

One reason for this behavior could be that the vendor driver always
enables RTS/CTS protection when at least one BA session is
established. So, AMPDUs will always be protected and don't need
to apply the RTS threshold. Not sure though if that was Ralinks
intention.

I'm thinking of doing the same in rt2x00? This would result in lower
throughput but should help collisions avoidance ...

Ideas?

Thanks,
Helmut



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