The MAC layer defines mechanisms for direct (single hop) communication between two devices. Such single hop data exchange is possible only within transmission range of participating pair of nodes. Data framing, device addressing, channel access management and device association/disassociation are the key MAC layer responsibilities. Communication on MAC layer is packet based. This means that data to be sent is encapsulated into a MAC frame that is passed to RF transceiver. A node shall accept only frames destined for it and upon their reception frames are checked on errors that could have occurred during transmission and corrected if possible. Each device is identified by unique 64 bit long MAC layer address that is used by sender as the destination for the packets sent on the MAC layer. Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) is the well known listen-before-send principle for managing access to a single physical channel among multiple devices. It ensures reliable communication and provides efficient usage of limited channel bandwidth. Upon higher layer requests MAC layer performs device association and disassociation (enters/leaves network).