Hello, I would like your advice on an issue I’ve been having.
I am using TOSSIM with tinyos-2.1.1.
Currently I have set up a small network of 6 nodes. Four nodes have three
(bidirectional) connections with other nodes, while two nodes have two
bidirectional connections with other nodes. All bidirectional connections have
a gain of –54. I am using the simple noise model. I have tried this with each
node booting up at the same time, at random times, and at random prime times.
Each node periodically (with the period being a random prime based off of it’s
ID so it can’t ever be the same prime as any other node) broadcasts a neighbor
discovery packet. Each node that hears that packet replies (not broadcasted).
With this simple setup and the precautions I’ve taken I would have expected the
collisions to be almost nonexistent. Instead while monitoring the SNRLoss
channel I frequently see things like this:
DEBUG (4): Lost packet from 2 to 4 due to SNR being too low (0)
DEBUG (4): Going to lose packet from 5 with signal -54.000000 as am receiving a
packet from 2 with signal -54.000000
DEBUG (3): Lost packet from 2 to 3 due to SNR being too low (0)
DEBUG (3): Going to lose packet from 5 with signal -54.000000 as am receiving a
packet from 2 with signal -54.000000
DEBUG (4): Packet from 5 to 4
DEBUG (4): - lost packet from 5 as SNR was too low.
-packet was lost.
DEBUG (3): Packet from 5 to 3
DEBUG (3): - lost packet from 5 as SNR was too low.
-packet was lost.
DEBUG (6): Lost packet from 4 to 6 due to SNR being too low (0)
DEBUG (6): Going to lose packet from 5 with signal -54.000000 as am receiving a
packet from 4 with signal -54.000000
DEBUG (5): Lost packet from 4 due to 5 being mid-transmission,
transmissionEndTime 5861071014697
DEBUG (4): Lost packet from 5 because 4 has outstanding reception, startTime
5861057892215 endTime 5861071014697
DEBUG (6): Packet from 5 to 6
DEBUG (6): - lost packet from 5 as SNR was too low.
-packet was lost.
DEBUG (4): Packet from 5 to 4
-packet was lost.
Another thing I noticed is time seems to be vastly faster than real-time. A
“millisecond” timer in a Node seems to run thousands of times faster than it
should.
Can anyone advise me on these issues? I apologize if I used incorrect
terminology or have made incorrect assumptions, I am still trying to understand
all of this.
Thanks
Anthony
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