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<DIV><FONT face=Verdana><FONT face="Times New Roman">Hello,
everyone</FONT></FONT></DIV>
<DIV><FONT face=Verdana><FONT face="Times New Roman"></FONT></FONT> </DIV>
<DIV><FONT face=Verdana><FONT face="Times New Roman"><FONT face=Verdana
color=#0000ff size=2>I have a problem on the" throughput and delay " when view
ing a network in a theoretical way, e.g. multi-commodity flow
model, or Queueing Network(Stochastic Optimization) .</FONT>
</FONT></FONT></DIV>
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<DIV><FONT face="Times New Roman">
<DIV><FONT face=Verdana color=#0000ff size=2>Suppose a simple wirless
network with 6 nodes. A traffic flow from node 1 to node 6, and the rate of each
link is shown in the following Fig.</FONT></DIV>
<DIV><FONT face=Verdana color=#0000ff size=2></FONT> </DIV>
<DIV><FONT face=Verdana><FONT size=2><FONT color=#0000ff><IMG
src="cid:__0@Foxmail.net"></FONT></FONT></FONT></DIV>
<DIV><FONT face=Verdana color=#0000ff size=2></FONT> </DIV>
<DIV><FONT face=Verdana color=#0000ff size=2>Intuitively, the throughput
is 6 = 4+2. Although the last hop link(4,6) and link(5,6) can
not be active simultaneously, the rate of the two links is much higher than
link24,and link 35. </FONT></DIV>
<DIV><FONT face=Verdana color=#0000ff size=2></FONT> </DIV>
<DIV><FONT face=Verdana color=#0000ff size=2>But we observe that each node
can not receive and transmit simultaneously. So it takes 3 slots for a packet to
travel from node 1 to node 6. Suppose at some slot 6 packets arrives
at node 1, then the throughput is 6/3 = 2 packets per slot, right?</FONT></DIV>
<DIV><FONT face=Verdana color=#0000ff size=2></FONT> </DIV>
<DIV><FONT face=Verdana color=#0000ff size=2></FONT> </DIV>
<DIV><FONT face=Verdana color=#0000ff size=2>I believe there's something
wrong to define throughput and delay in the way above. But I am really getting
confused . why m</FONT><FONT face=Verdana color=#0000ff size=2>ost
theoretical models concern on the throughput of the system without
taking DEDLAY into account? Maybe it is about different layers
-Network layer and MAC layer£¿</FONT></DIV>
<DIV><FONT face=Verdana color=#0000ff size=2></FONT> </DIV>
<DIV><FONT face=Verdana><FONT color=#0000ff size=2>Regards,</FONT></FONT></DIV>
<DIV><FONT face=Verdana color=#0000ff size=2></FONT> </DIV>
<DIV><FONT face=Verdana color=#0000ff size=2>-Kara-</FONT></DIV>
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<DIV><FONT face=Verdana color=#0000ff size=2></FONT> </DIV></FONT></DIV>
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<DIV><FONT color=#c0c0c0><FONT size=2><SPAN>CaiShun</SPAN></FONT></DIV>
<DIV><FONT size=2>2009-02-25</FONT></FONT></DIV></FONT></BODY></HTML>