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Sensor Netw ork Services for Mobile Users
Chenyang Lu
Department of Computer Science and Engineering Washington University in St. Louis 2
Hint on Question 5.2 in HW2
Compute the maximum processor utilization that can be
assigned to a Deferrable Server to guarantee the task set (periodic tasks).
1/ 1/
2 2 1 1 2 1 2 1
n n s s p s s p s s
U U U U U n U n U U ⎡ ⎤ ⎡ ⎤ ⎛ ⎞ ⎛ ⎞ + + ⎢ ⎥ ⎢ ⎥ + ≤ + − ⇒ ≤ − ⎜ ⎟ ⎜ ⎟ + + ⎢ ⎥ ⎢ ⎥ ⎝ ⎠ ⎝ ⎠ ⎣ ⎦ ⎣ ⎦
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Utilization Bound w ith DS
Under RMS As n ∞:
When Us = 0.186, min Ub = 0.652
System is schedulable if
⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎣ ⎡ − ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ + + + = 1 1 2 2
/ 1 n s s s b
U U n U U ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ + + + = 1 2 2 ln
s s s b
U U U U ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ + + ≤ 1 2 2 ln
s s p
U U U
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Fire Monitoring
Fireman in wild fire
- report temperature within 100m of the moving user every 2s;
- temperature data must be no more than 1s old
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Navigation through Fire
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Cargo Tracking
Shipping Yard Ship Train Truck Customer, Shipper, Customs