20
Markov process of the temperature
sensor model.
TABLE 11.4
Energy Consumed by a Sensor Network with
and without a Burst Switch
Network model Energy Consumed (kJ)
Without burst switch 150.9
With burst switch 65.8
Minimum Energy=Power Considerations 217
ignored, and when valid packets arrive, the smart buffer must also wake up the processor
to respond appropriately [20,21].
The amount of power savings allowed by the smart buffer is highly dependent on the
scenario. First, the smart buffer must consume less power than the active tag controller,
which is supported by the data shown in Section 11.4.2.10. Second, the amount of power
savings depends on how many successful accesses the tag receives on average, how long
the processor is active, etc. We examine several scenarios and the smart buffer impact in
Section 11.4.2.11. As seen in Section 11.4.2.10, the power savings from the smart buffer can
be several orders of magnitude for the microprocessor-based tag.
11.4.2.1 Algorithm for RF Transceiver Coprocessor
The conceptual ?¬‚ow in Figure 11.21 shows the mechanism for the RF transceiver coprocessor,
that is, the smart buffer. In the ?¬?rst four states on the left of the ?¬?gure, the smart
buffer veri?¬?es the message preamble and buffers the incoming packet. The smart buffer
then checks to see if the packet was intended for this particular tag.
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