1
System component overview.
RFID
mote
RFID
reader
Battery
Comm
Serial comm
Packet
management
SMAC
RFID reader
protocol
RFID reader
I/O
Serial
port 2
Battery
ADC
Mica2
radio
Serial
port 1
FIGURE 17.2
RFID reader mote software components (with SMAC RF communication submodule).
A Prototype on RFID and Sensor Networks for Elder Health Care 315
memory resource, the packet management submodule manages a ?¬?xed memory size
associated with each communication packet. The serial communication submodule is
the TinyOS communication module over serial port. There are a few RF communication
modules developed by various members of the open source community. TinyOS has
an RF communication module [18]. CrossBow Technology has a mesh RF communication
module [17]. An S-MAC module is also available for this platform [19]. The RF
communication submodule is designed to allow for easy replacement. All three
RF communication submodules are wrapped around a common interface and are selected
at compile time.
The RFID reader mote software queries the RFID reader simulator every second for tag
messages. In response, the RFID reader simulator sends a set of tag messages to the reader
mote. Tag messages are queued by the RFID mote software and transmitted over RF to the
base station mote. To allow ef?¬?cient transmission, up to 12 tag messages are encoded into a
single RF message.
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