[ns] Fairness in wired-cum wireless scenario

Sat May 29 06:03:08 PDT 2004

Hi all,
I am using ns2.27, simulate wired-cum wireless: 1
wired node, 1 base station, 8 mobile nodes. 8 seperate
UDP CBR 1Mbps transmissions from the wired nodes to 8
mobile nodes. 
802.11b 11Mbps, RTS/CTS enable and disable.
UDP payload 1460 bytes (maximum size because threshold
fragmentation of Ethernet, which connects wired- to
wirless-network, is 1500 bytes)

Some strange results obtained:

1. There's no fainess between connections. Some gets
throughput near 1Mbps, some very low, almost 0. (as I
understand, THEY MUST BE FAIR) for both cases RTS/CTS
on or off.

2. The result doens't depends on the positions of
wireless nodes at all, close or far from base station,
static or mobile.

3. The result changes if transmitting start time of
each connection changes. But still no fairness.

4. I look at the trace file, all packets are
fragmented at 1000 bytes. Why? How to change this
threshold?

I send here my tcl script. Pls look at it.
Anyone can help me? I may have mistake in the script.
Any parameters need to be concerned?

Thanks in advance
Eric

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