Abstract:
Wireless sensor networks represent a key technology enabler for enhanced health care and assisted living systems. Recent standardization efforts to ensure compatibility among sensor network systems have produced the IEEE 802.15.4 standard, which specifies the MAC and physical layer behaviour. Energy and network life time are two critical factors for WSN performance. IEEE 802.15.4 is a standard used for low data rate Wireless Personal Area Networks (WPANs). Medium Access Control layer (MAC) of IEEE 802.15.4 plays an important role in the performance of Wireless Sensor Network (WSN). The unique feature of this MAC layer is the superframe structure, which allows devices to access channels in a Contention Access Period (CAP) or Collision Free Period (CFP) and use beacon based synchronization mechanism. In this paper, we propose a cross-layer framework to prolong the network lifetime, to improve the energy and to lower the latency of WSNs based on the IEEE 802.15.4/ZigBee standards. To cover all the scenarios, we have considered hierarchical topology and peer to peer beacon enabled network. The performance metrics are evaluated using simulation results.

Keywords: IEEE 802.15.4, Wireless Sensor Networks, Medium Access Layer, Hierarchical and peer to peer topology