Design Wireless Sensor Networks Which Support Users' Mobility

Wireless Sensor Networks (WSN) can be taken as a bridge between physical world and information world which largely extend existing network's function and enhance people's capability of knowing the physical world, and find applications in many different areas, including military surveillance, environment monitoring, smart home and offices, and many others. If WSN can support mobility, it will be more popular and obviously improve networks'performance. But designing a suitable mobility support scheme for WSN which composed by sensor nodes limited in power, computational capacities and memory, becomes a challenge.In this thesis, on the basis of deeply study 802.15.4 and ZigBee standard, a two layer hybrid network structure which can support mobility and have good expansibility is proposed, a Real-Time Operating System and Real-Time Communication Protocol Stack suitable to WSN is designed, and key technology in WSN is also mentioned. In order to make WSN have QoS guarantee and mobility support ability, a differentiated services scheme that allocates resource based on users'movement state and transaction is introduced, and mobile users'movement prediction algorithm and resource reservation method which provides the mobile user fast handoff service with QoS guarantee is proposed. The above mentioned algorithm and scheme is implemented on test-bed. Testing result shows that handoff delay and packet loss ratio is reduced, meanwhile the mobile users'QoS is guaranteed.