IEEE 802.15.4

ZigBee is officially a wireless network protocol that is designed to be used with low-data-rate sensor and control networks. ZigBee can also eliminate the need to string wires all over the place as it can easily reach data rates comparable to and above standard RS-232 and RS-485 wired protocols. Although an IEEE 802.15.4 network can easily obtain RS-232 speeds, you wont see many battery powered applications of IEEE 802.15.4 networks replacing RS-232 communication links,especially if the traffic on the IEEE 802.15.4 based pseudo RS-232 link is heavy.



ZigBee is a standards based network protocol supported solely by the ZigBee Aliance that uses the transport services of the IEEE 802.15.4 network specification. The IEEE 802.15.4 specification also uses internal layers, which are normally referred to as sublayers. The wireless 802.11b specification and the wired 802.3 specification also employ the concept of sublayers. The IEEE 802.15.4 specification calls out a pair of 802.15.4 sublayers, the PHY and the MAC.

If we relate the IEEE 802.15.4 sublayers to the ZigBee protocol stack, the ZigBee PHY sublayer, which is actually the IEEE 802.15.4 PHY sublayer, is all about the radio and the generation of the radio link. A ZigBee stacks PHY responsibilities include receiver energy detection, link quality indication and clear channel assesment. The ZigBee stacks PHY is also primarily responsible for transmitting and receiving packets across the magnetic medium. The ability to sniff the air for other nodes is very important in the ZigBee and IEEE 802.15.4 world as this is what is done to determine if a new ZigBee or IEEE 802.15.4 network can be spawned.