[j-sim-users] Re: Sensorsim packet loss

[Nicholas Merizzi]

Hi Conor
    It's a little challenging to guarantee 100% delivery rate especially 
in sensor networks. Since these are energy constrained devices you would 
not want to use TCP(because of high overhead). Also since J-Sim only 
currently supports Mac802.11 which is not designed for sensor networks 
(idle listening, and overhearing problems) you are looking at draining 
your battery really quickly!
    An alternative that I am looking into is using a sort of High 
priority flag on certain packets that need immediate attention.

If you were to simulate TCP with 802.11 attach a port to a plotter and 
watch the energy drop really fast! There is also another problem when 
you combine the wireless package with the sensor package: the energy 
models. Each package has their distinct energy model. I have re-design 
the sensor network package so that it correctly fits into the wireless 
package:

http://www.cas.mcmaster.ca/~merizzn/

If anyone has feedback for me on those models or working on something 
similar let me know!  I am in the process of breaking up the Mac 
component so that other Mac protocols can be used.

-Nicholas


Conor Beverland wrote:

>Further to my previous question, I've noticed that adding these lines
>from the wireless tutorial seems to help with the packet loss problems
>I've been seeing:
>
>#enable route_back flag at PktDispatcher
>! pktdispatcher setRouteBackEnabled true
># since 802.11 provides link broken detection, we set the flag in AODV
>! aodv enable_link_detection
>
>However, while enable_link_detection is mentioned in the tutorial, I'm
>not sure what setRouteBackEnabled actually *does* (haven't had time to
>delve into the PktDispatcher code and it isn't mentioned in javadoc..)
>
>Also, I'd still like to know if it's possible to guarantee packet
>delivery in the sensor network. Would I have to replace the
>WirelessAgent class with something like drcl.inet.transport.TCP?
>
>Thanks,
>Conor
>
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