The IEEE is an international non-profit organization directed toward the advancement of electrical, electronics, communications and computer engineering. In wireless communication the IEEE has standardized fundamental protocols behind such technologies as WiFi, Bluetooth, WiMAX and many others. In 1998 after realizing the need for LPW technology the IEEE started developing 802.15.4 standard that was approved in 2003 with a revision following in 2006. As it is common for all IEEE wireless standards only two OSI layers are specified: physical (PHY) and medium access control (MAC). On these levels only direct, single hop, communication is possible. Currently IEEE 802.15.4 is the most commonly used basis for wireless sensor networking.