This will ensure that
nodes closer to the sink node are not favored over nodes far away from it.
Unlike SMAC, ARC does not provide any periodic listen/sleep mechanism.
Moreover, this protocol accentuates per-node fairness while SMAC trades it
o?® for further energy savings.
4.10 ZigBee and the Industry Standard IEEE 802.15.4 Protocol
The 802.15.4 standard [22] is a simple packet data protocol for very low duty
cycle wireless networks. It is a CSMA with collision avoidance and optional
time slotting protocol. The ZigBee technology is based on the IEEE 802.15.4
protocol. Its applications vary from home and industrial automation to remote
control and medical monitoring. It uses a wide range of frequencies: sixteen
channels in the 2.4 GHz ISM band with a bit rate of 250 kbps, one at 868
MHz with a bit rate of 20 kbps, and ten at the 916 MHz ISM band with bit
rate of 40 kbps. It can accommodate up to 264 nodes in the network.
Three types of devices are defined (see Figure 13): Network Coordinator,
Full Function Device, and Reduced Function Device. Network Coordinator
(Master node) is aware of all the nodes in the network. Full Function Device
supports full 802.15.4 functionality, and it has additional memory and computing
power which makes it ideal for a network router. Reduced Function
Device has limited functionality to prolong its battery life time and is usually
deployed at the network edges. While Bluetooth supports moderate duty
cycle with short life battery time, ZigBee on the other hand, supports very
low duty cycle, and long life battery time.
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