tcp variants(reno,westwood,bic)

Okay, I already told you what to do in your other question, but here it is in a more specific form:

1. Find the specifications for each of the stack you want to evaluate. This can be a difficult task, because not all of them are easily found, but reading RFCs probably helps.
2. Do a differential compare between the stack types to see what kind of features/behavior they have that other stacks don't. Examples are RTO, Fast Retransmit, Slow Start, Congestion Avoidance, Fast Recovery, Binary Increase Congestion Control, and multiple algorithms looking at send rates and RTT.
3. Find out what OS has what kind of stack. Most rare stacks are probably available for UNIX style OSes.
4. Setup test systems that use the particular stack (this will be quite time consuming) and run tests while capturing
5. Analyse traces to see if the behavior shows as expected. Filter for tcp.analysis.flags to see TCP expert messages, and use I/O Graph and the TCP graphs in the statistics menu
6. Write your paper.

Good luck. Don't ask this question again before you have more specific things to ask, please.

I think a network simulator is a far better tool to compare different TCP implementation details, than only looking at differences in the capture file. Obviously Wireshark will be very valuable, but within a network simulator you'll have much more options to trace and analyze performance characteristics.

Network simulators:

http://www.wand.net.nz/~stj2/nsc/
http://www.wand.net.nz/~stj2/nsc/
many more. Just search google.

Regards
Kurt