[ns] Satellite Simulation : Collision problem

[Ankit Jain]

Dear All,

I am a student at Ahmedabad(india) and currently
working on ns.

Have u ever simulated satellite links using ns? I am
having some problems.

When adding a gsl to a node we have to specify a Mac
type, (medium access control) either Mac/Sat or
Mac/Sat/Unslotted . what are their functionality?
I know tha in uslooted aloha collision may be. But
when i am simulating a TCP connection using a
geo-repeater satellite and source/destination
topology, the trace file is having entries which shows
that there is collision of a data packet (1040 bytes)
and a ack (40)
. How it is possible as satellite links are using two
diff channels for uplink and downlink.

Script source code:
I have modified the sat-repeater.tcl script for
Mac/Sat/UnslottedAloha instead of Mac/Sat

Please solve this query.


Ankit



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