Specifications

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relays controlling the different heating and cooling options so that the appropriate
action can be carried out.
The question becomes which form of wireless technology will be most effective
for caring out these decisions and actions. With so many different choices of
wireless communication, certain key features must be accounted for and
analyzed before we can select the best option. The three biggest options in the
wireless technology field that can give us a better understanding are: Bluetooth,
ZigBee and Wi-Fi®. Each of these wireless protocols have pros and cons that
will help us choose the best communication system for our components. The
sections following outline and describe these communication protocols.
2.6.3 IEEE 802.15.4 – ZigBee
ZigBee is a specification for a suite of high-level protocols using small, low-
powered digital radios based on IEEE 802.15.4 standard for low-rate wireless
personal area networks (LR-WPANs). The 802.15.4 protocol offers the lower
network layers of wireless personal area networks (WPANs) which are focused
on the simple, low-cost, low-power consumption, simultaneous communication
between devices. ZigBee is targeted for radio-frequency applications that require
low data rate, a long battery life, and secure mesh networking. Mesh networking
provides high reliability with a more extensive range. The low cost of the ZigBee
protocol allows the technology to be widely deployed in wireless control and
monitoring applications and the low-power usage allows for longer life with
smaller batteries. ZigBee is less expensive and simpler to operate compared
with other WPANs like Bluetooth.
The ZigBee wireless standard is a great option for this project. An external
ZigBee device could interface with both our main and secondary microcontroller.
Many microcontrollers‟ have ZigBee transceivers already built in; saving space
on our printed circuit board (PCB). Other house appliances like the home
telephone, microwave, Wi-Fi and Bluetooth share the 2.4 GHz ISM band,
causing noise for the ZigBee device. ZigBee has low data rates, meaning that
less data needs to be transmitted, making the noise a non factor for the system.
The low power physical layer of the ZigBee allows the ability to transmit of a
range up to 75 meters, which is more than enough for the scale of this project.
Another great fact is that for an individual device to pass the ZigBee certification,
it must have a battery life of at least two years, proving how low power ZigBee
communication is. Table 6 pictured below illustrates the pros and cons of the
zigbee wireless standard protocol.