Re: [6tsch] simulation for random schedule allocation

[<[e-mail]>]

Hi Xavi,

Thanks for your explanation.  I have better understanding now.

I have one more question.

You mentioned “there might be more than one link to a neighbor”.   Say Node X selected only one neighbor Node Y and requests one link to Node Y.  The resulting number of links associated with Node X can be two (2) when Node Y also selected Node X as its neighbor and requested one link to Node X.  Is my understanding correct?

Yoshihiro Ohba


From: [e-mail] [mailto:[e-mail]] On Behalf Of Xavier Vilajosana Guillen
Sent: Thursday, June 27, 2013 1:33 AM
To: ohba yoshihiro
Cc: [e-mail]
Subject: Re: [6tsch] simulation for random schedule allocation

Hi Yoshihiro,
you are right, the formulation of the sentence is not correct. Should be:

“Topology: Random, where each node requests a random number of neighbours between 2 and 10.”
this means that each node when created requests a number of neighbors between 2 and 10, meaning that other nodes when are created also request that number of neighbours and therefore a node can have more than 10 neighbours, because other nodes selected it as a neighbour. From the simulation results I see that nodes have between 5 and 11 neighbours usually.
However, from the numbers you point, 28 represents the number of allocated links (number of allocated cells in the schedule) to its neighbours, there might be more than one link to a neighbour in that case.
regards,
Xavi

Xavi

On Wed, Jun 26, 2013 at 7:28 AM, <[e-mail]<mailto:[e-mail]>> wrote:
Hi Xavi,

Thank you very much for the simulation.

I am trying to understand the simulation model from your description and the result.

“Topology: Random, where each node has a random number of neighbors between 2 and 10.”

“
************************ requesting 1 links
Node,Allocated Links,Collisions,Percentage
0,28,0,0.0
“

In the above result, does Node 0 actually have 28 neighbors?

Regards,
Yoshihiro Ohba

From: [e-mail]<mailto:[e-mail]> [mailto:[e-mail]<mailto:[e-mail]>] On Behalf Of Xavier Vilajosana Guillen
Sent: Wednesday, June 26, 2013 3:46 AM
To: [e-mail]<mailto:[e-mail]>

Subject: [6tsch] simulation for random schedule allocation


Hi all,

I prepared a little simulation to see how random schedule allocation behaves. (I have the code in Java in case someone is interested)

here there are some details (everything can be tuned in case someone wants to point me to a special case)

Network: 50 nodes

Topology: Random, where each node has a random number of neighbors between 2 and 10.

Each node requests a link to each of its neighbors. This is done from 1 to 10 times (i.e 10 tests, the first requesting 1 link to each neighbour, the second 2, etc.. up to 10 links to each of the neighbors, can be configured)

The slotframe is 101 slots and 16 channels.

The simulation prints statistics for the test (and the collisions if we are interested.)
I used pseudo random generator from the java language assuming it provides uniform or almost uniform distribution.
The allocation counter counts both the number of links allocated as tx and the number of links allocated as rx due to a neighbour allocating a link to the actual node. The percentage is the % of collisions w.r.t the allocated links.
Worst case is around 11% when allocating 10 links to each neighbour in that 50 node network.
I can play more on it but I wanted to share that initial results.
please see attached file for the results.
regards,
Xavi