IEEE 802.15.4 is a standard used for low data rate Wireless Personal Area Networks (WPANs). It offers device level connectivity in applications with limited power and relaxed throughput requirements. Devices with IEEE 802.15.4 technology can be used in many potential applications such as home networking, industry/environments monitoring, healthcare equipments etc. due to its extremely low power features. Medium Access Control layer (MAC) of IEEE 802.15.4 plays an important role in the performance of Wireless Body Area Network (WBAN). The unique feature of this MAC layer is the super frame structure, which allows devices to access channels in a Contention Access Period (CAP) or Collision Free Period (CFP) and use beacon based synchronization mechanism.