Study On Hidden Node Issues Of IEEE 802.15.4 System

Through reading lots of thesis, papers, journals concerning hidden node problem in IEEE802.15.4/Zigbee.two ideas have been proposed in my thesis.First, a new distribution mechanism based on grouping strategy in zigbee beacon enable network which could divide CAP more wisely and realistic .It could improve QoS of the network. Second , A new Energy efficient scheduling for cluster-tree has been proposed which could save more energy while respecting e2e deadlines of the flows and avoiding possible inter-cluster collisions.This thesis consists of six chapters:The first chapter is introduction to WPAN and related research which have been released in main areas of IEEE802.15.4/zigbee.The second chapter, the IEEE 802.15.4/ZigBee protocol was introduced. They are the physical layer and media access control layer in IEEE 802.15.4 standard, the network layer and application layer in ZigBee specification respectively. The corresponding theories provided the foundation for the following chapters.The third chapter, a hidden node collision avoidance strategy based on region division and slot backoff is proposed: dividing the region of network coverage to make sure nodes in same sub-region within the carrier sense range of each other. Meanwhile adjusting superframe structure slightly by dividing CAP to allocate slots to grouped nodes in different sub-regions, making transmission of hidden nodes be staggered by slot backoff. Simulation results demonstrate my algorithm can solve the IEEE802.15.4 hidden node problem effectively.The fourth chapter shows how to minimize the energy consumption of the nodes by setting the beacon interval (TDCS period) as long as possible where respecting e2e deadlines of the flows and avoiding possible inter-cluster collisions.In the last chapter, a conclusion for the entire thesis was made. And the issues that needed to be investigated and solved in the future research on LR-WPAN were pointed.