ult M i-channel, mult i-r adio
COSC 6590 Fall 2007
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Single Channel: Capacit y
Theoretical upper limit of the per node throughput capacity :
Theoretically achievable capacity of every node in a random static wireless ad hoc network with ideal global routing and scheduling ...
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Single Channel: Capacit y (2)
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Single Channel: Capacit y (3)
Experimental results from CSMA/CA MAC on a
string topology. Throughput 1 / n
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Reasons
Exposed ter minal pr oblem (main factor!) Hidden terminal problem High error rate on wireless channel MAC characteristics etc.
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Solut ion
Multi-channel, multi-radio Use multiple frequencies to transmit on.
802.11a has 12 non overlapping channels in
the 5GHz each range. channel is 20MHz wide
5.200 GHz, 5.180 GHz, 5.220 GHz, 5.240 GHz, 5.260
GHz, 5.280 GHz, 5.300 GHz, 5.320 GHz, 5.745 GHz, 5.765 GHz, 5.785 GHz, 5.805 GHz
Use multiple antennas to transmit and
receive at the same time
wireless routers
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M ult i-channel M ult i-r adio Net wor ks
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Why use mult i-channel, mult ir adio?
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Design I ssues
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Design I ssues (2)
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Design I ssues (3)
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Pr ot ocols
1...