[olsr-dev] adding received signal info

Andreas T√łnnesen (spam-protected)
Tue May 24 13:43:10 CEST 2005


spoggle wrote:
> If you get results from this, please post them here.  How much of a 
> burden is collecting the signal strengths?

When I fiddled with the link-layer quality stuff some time ago I gave it
up for a couple of reasons. Some of them Bruno has already mentioned.

- The default driver only supports collecting statistics from 8
   neighbors in ad-hoc mode.
- You need an ARP entry for the node to collect statistics from.
   Since all OLSR traffic is broadcasted you'll need to send some
   unicast traffic to the node to initiate the ARP lookup sequence.
   (One could however study the Linux netstack to see if it is possible
   to actually build an ARP whohas from userspace and have the stack
   cache the reply)
- The results are not consistent with different hardware. I have not
   tested much with this but I was told that different HW would yield
   different results. I was considering adding some threshold for
   neighbor registration - but I ditched that idea after hearing this.

The code now resides in src/linux/link_layer.c for historical reasons
only(it is diffed out). All it did was maintain a table of neighbors
and check their link-layer quality regulary. If you check out an earlier
version(pre 0.4.8 I think?) and run it with the -llinfo switch, it'll
display link info statistics on stdout.
All of this only goes for Linux.

I wrote briefly about this in my thesis:
http://www.olsr.org/docs/report_html/node132.html

- Andreas

-- 
Andreas T√łnnesen
http://www.olsr.org



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