Basics of IEEE 802.15.4 PHY/MAC protocol

What is IEEE?
The Institute of Electrical and Electronics Engineers, often called eye triple-ee. It is a U.S.-based organisation of engineers, scientists and students involved in electrical, electronics and related fields. It also functions as a publishing house and standards-making body.

What is wireless communication?
Wireless communication is the transfer of information over a distance without the use of electrical conductors or "wires." The distances involved may be short (a few metres as in television remote control using infrared light) or long (thousands or millions of kilometres for radio communications).