Receiver-based asynchronous wakeup is essentially the mirror image of
sender-based, where the wakeup burden is now with the receiver. Figure 12
shows the principle, which underlies the Etiquette protocol [33]. A sleeping
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Sender-based asynchronous wakeup can also be viewed as a non-synchronized
Curt Schurgers
Fig. 11. Sender-based asynchronous wakeup.
node A now periodically sends announcements and listens for a reply. A node
B that wants to wake up A listens until it hears such an announcement and
then sends a reply back. The maximum time is again equal to the period
(although some variations have been proposed [33]). In Etiquette, after a
sleeping node has been contacted, it arranges a future time to schedule the
data transmission, which essentially corresponds to a particular choice of MAC
protocol. In its basic form, the wakeup portion of the protocol can be viewed
as a receiver-based solution.
Fig. 12. Receiver-based asynchronous wakeup.
It is possible to directly compare the characteristics of rendezvous-based,
sender-based and receiver-based asynchronous wakeup by investigating Figures
10, 11 and 12, which all result in approximately the same maximum
wakeup delay, namely one period. In rendezvous-based wakeup, the contacting
or sender node, in this case B, has less of an overhead compared to the
other two schemes. However, the sleeping node A, has to be awake for a larger
fraction of the period and therefore has higher average power consumption,
as follows from equation (7) in Section 1.
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