imsg
act : Current drawn in transmitting one packet when the radio is in active
mode (no LPL). Its value is given by the following expression:
10 Similar values for ilpl
sample were reported in [9].
274
imsg
act =
(mpr + me + mpp) ?¤ tpkt
tx ?¤ (irad
tx ??’ irad
act )
3600
=
(240 + 52 + 90) ?¤ 0.02 ?¤ (16 ??’ 8)
3600
= 0.02mA. (2)
imsg
lpl : Current drawn in transmitting one packet when the radio is in LPL
mode. Its value depends on the sleep period, tlpl
slp used by the radio. More
specifically,
imsg
lpl =
(mpr + me + mpp) ?¤ (tpkt
tx + tlpl
slp) ?¤ (iproc
act + irad
tx )
3600
=
(240 + 52 + 90) ?¤ (0.02 + tlpl
slp) ?¤ (8 + 16)
3600
. (3)
ievent
awk : Amortized current drawn in staying awake due to events. Its value
depends on two factors:
1. tawk - Time (in seconds) that the heaviest-loaded XSM is awake every
hour due to events. We assume that an XSM close to the base station
stays awake for 10 s after the occurrence of an event. This may be
for routing all event detection messages. With the assumption of six
events every hour, tawk = 60 seconds in ExScal.
2. islp
sensors - The current consumed in the active mode by all the nonwakeup
sensors. From Table 2, we obtain, islp
senors = 0.595+6.48 =
7.075 mA.
With the above values and the fact that the processor is also awake when
the XSM is awake due to events, we obtain,
ievent
awk =
tawk ?¤ (iproc
act + islp
sensors)
3600
=
60 ?¤ (8 + 7.
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