[OLSR-users] LQ Routing and 802.11b Link Speed

[Holger Mauermann]

Holger Mauermann wrote:
> What about measuring not only the packet loss, but also the round
> trip time to the neighbors?

Forget my last post. The RTT depends on the link load and leads to very 
frequent route changes...

However, recently I read something about Packet-Pair based bandwidth 
estimation and Expected Transmission Time (ETT) and it looks very 
interesting. Consider the following real life example with 3 links:

A-B: 24 Mbps, ETX 1.0
A-C:  1 Mbps, ETX 1.5
B-C: 11 Mbps, ETX 1.0

To reach C from A olsr currenty prefers the short, bad 1 Mbps link. With 
ETT it could use the two fast links A-B and B-C because the total ETT is 
only 2.5 ms instead of 15 ms:

ETT = ETX * S / B       S = Packet size, B = Bandwidth

A-B: ETT 0.8 ms (S = 1 KByte, B = 1200 kByte/s)
A-C: ETT  15 ms (S = 1 KByte, B =  100 kByte/s)
B-C: ETT 1.7 ms (S = 1 KByte, B =  600 kByte/s)

Any ideas if this could be implemented in olsr?

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