[olsr-dev] Question about LQ theory

[Thomas Lopatic]

Hi there,

Whoops, I just found this unanswered e-mail in my incoming mailbox.
Sorry for the oversight.

[802.11 broadcasts are sent at a lower bitrate than unicasts; the packet
loss for broadcast packets is thus different from the packet loss for
unicasts; hence, one might want to send unicast probe packets to measure
unicast packet loss]

Yes, true, you could also try and send extra unicast packets to each
neighbour. However, as each node would send packets to each of its
neighbours, that could be a lot of packets. Hence, we decided to stick
to packets that were already there, i.e. OLSR broadcast packets.

What we observe is a bit different anyway. Sometimes for some reason the
measured packet loss is higher than the actual packet loss. I've read
somewhere that broadcast packets do not get acknowledged in 802.11 and
hence not re-sent in case of packet loss, which might be an explanation
for this behaviour.

-Thomas