802.15.4 MAC layer
Handles all access from the upper layers to the physical radio channel
Generating time synchronization frames (for PAN coordinator)
Synchronization frames
Association and disassociation
Device security and support of security mechanisms implemented by the upper layers
Managing channel access and giving priority for devices to transmit at specific times
Maintaining a reliable link (error detection)
Using a 16-bit ITU cyclic redundancy check
Access to the medium is contention based
Uses CSMA/CA