Biomedical Engineering Reference
In-Depth Information
Fig. 7
Sensor initialization in U-MAC
of the new sensor. The reception of a NCTS means that the new sensor node has
to reduce its transmitting power or the data rate. If the new sensor parameters are
admissible, the coordinator node will reply with a clear-to-send (CTS) message
while the neighbouring sensor nodes refrain from sending any messages. The data
transmission occurs after the initialization. The link parameters can be dynamically
adjusted during the data transmission using the
hello
messages according to the
requirement of the sensor nodes.
Drawbacks:
While this MAC protocol allows more dynamic usage of the UWB
channel resources, it allocates significant processing load to the sensor nodes. In the
context of WBANs, it is advisable to minimize the processing at the sensor node
end in order to reduce the power consumption. Similar to the UWB
2
MAC protocol,
the U-MAC uses a UWB receiver at the sensor node end in order to receive
hello
messages and other control messages, which leads into increased power consumption
and complex hardware implementation.
Dynamic Channel Coding-MAC
The DCC-MAC presented in [
34
] and [
35
] uses dynamic channel coding (DCC) in
order to mitigate the multiple access interference. This MAC protocol assumes that
all the sensor nodes transmit at maximum allowable transmit power in contrast to the
power control mechanisms used in Sects. “Preamble Sense Multiple Access-Based
MAC” and “U-MAC”. A cross layer technique is suggested in this MAC protocol in
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