Optimization Research And Realization Of ZigBee Network Layer Based On Distributed Address

Increasing deploying of the wireless sensor network raises to the increasing requirements for high efficient communication protocols. ZigBee, as the most popular protocol, has been wide utilized in intelligent agriculture, smart home, environmental monitoring, medical care and so on, due to the low cost, low power consumption, high reliability. However, currently, the limitations as version differences are extremely blocking its further applying. Therefore, the improved ZigBee protocol is greatly desired in order to improve the reliability and stability and expand its range of application areas.The main works of this thesis are as follow:the hardware design of wireless node with MSP430F5438and CC2420, the software realization of ZigBee protocol network layer using the real-time embedded operating system FreeRTOS, the contents include creating the network of the coordinator, joining and leaving the network, data sending and receiving, network address assignment, network maintenance and implementation of the Cluster-Tree routing algorithm. We find shortcomings exist in the routing efficiency, parent node selection and network address assignment by experimental test, therefore the CTBN routing algorithm, the adaptive parent node selection and address recovery redistribution are proposed aiming at the shortcomings. At last, four experiments are designed and the experimental results show the good effect.Specific works are as follows:Firstly, the background and the software platforms are introduce respectively. Regarding to the background, it describes the characteristics and applications of the ZigBee protocol, points out the shortcomings that exist in the mainstream protocols, so that to demonstrate the significance of this study. As to the software platform, it mainly describes the specification of the PHY layer, the specification of the MAC layer and the CSMA-CA algorithm; also introduces the works of the real-time embedded operating system FreeRTOS which is employed in the system.Secondly, the hardware design of the using platform is described. The hardware design consists of four modules, namely single-chip module, power module, the wireless transceiver module and the serial communication module, microcontroller used the MSP430F5438, and the radio frequency chip used CC2420that working on the2.4GHz, the function of each module and the interface between each module are introduced, schematics of each module also be given.Thirdly, the software implementation of ZigBee’s network layer is introduced. The content consists software integrated development environment IAR and the specification of ZigBee’s network layer. The network specifications include data services, managed services and network topology. Introduction focuses on the specific realization of the various functions of the network layer, including create networks, join and leave the network, send and receive data control, network address allocation and network maintenance, the software block diagram of the various functions are given, the important functions used in the realization are provided as well. Finally, it introduces the network layer’s routing algorithm, including the AODVjr algorithm and Cluster-Tree algorithm, the Cluster-Tree algorithm used is the highlight contribution in this thesis.Finally, the optimization and realization of the network layer are presented. Aiming to over shortages in the network layer, the author puts forward a number of improvements to the network layer. There are three aspects:The first is the routing algorithm optimization, proposing the CTBN algorithm based on neighbor table; the second is the parent node selection optimization, putting forward the adaptive parent node selection; the third is the optimization of the network address assignment, adopting "reporting" mechanism. And then the author designs an experiment to prove the effect by compare the experimental results with the orginal one.The thesis simplified realizes the ZigBee protocol’s network layer using the real-time embedded operating system FreeRTOS, based on other’s MAC layer and PHY layer. And also in order to reduce shortcomings in the network layer, improvements to be presented, the experimental results shows the improved protocol has been greatly enhanced in reliability and stability, the protocol meets the requirements of most applications and has broad marketing, it will promote the ZigBee’s application development.