| ZigBee is a new short-range wireless network technology with the features of low speed,low power,low cost,high reliability,ad hoc networks,low complexity,BVR,etc.It's mainly used for domains such as remote control,automatic control and so on,which can also be embedded in a variety of devices.In recent years,with the rise of the Internet of Things,ZigBee technology has a wide range of application prospect in the Internet of Things such as smart home,industrial monitoring,health care and other fields for its low power consumption,low cost,self-organization,and high reliability.The diversity and asymmetry of the ZigBee network topology lead to the consumption of coordinator,routers and other core network nodes power rise as the number of nodes increases.Therefore,it is important to design the dormancy mechanism,making the system power balance,obtaining longer network life cycle.If the key management mechanism is optimized,we can get quick access to the communication link key.How to realize the efficient data segmentation forwarding mechanism and the corresponding feedback retransmission mechanism is a new problem to be solved in the development of ZigBee network application for adapting to the efficient and reliable transmission of large data volume.The paper research and network practical verification are based on the above problems with Microchip's MRF24J40 MC transceiver modules.The main work and innovations of the paper include:1.Design and implement an idle broadcast dormancy mechanism.The router sends a dormancy request to the coordinator when no data is sent to the coordinator.After receiving the dormancy request,the coordinator sends the broadcast dormancy order frame to notify the router to sleep.Then all devices are awaken by the watchdog timer to achieve synchronous dormancy of the whole network.This paper analyzes the impact of Idle broadcast dormancy mechanism on network power balance by testing the power consumption of the equal amount of data transmission between the coordinator and the router in the ZigBee network which adopts and does not adopt the mechanism.2.A communication link key acquisition process optimization scheme is proposed.Aiming at the problem of automatic transmission in protocol that the receiver and the sender cannot automatically send the link key to the trust center,this paper realizes data communication based on encryption by using the trust center actively to notify the receiver to send the link when the trust center receive the link key request from the sender.Combined with route discovery process,the protocol process is optimized.Finally,by comparing the communication delay of the link key acquisition process before and after the specific network scenarios,the advantage of the encrypted communication delay performance is verified.3.An efficient data segment forwarding mechanism and the corresponding feedback retransmission mechanism are proposed.For the restriction of ZigBee physical layer protocol packet size,a packet which exceeds 127 Bytes of length can't be sent.If the packet exceeds its specified size,the custom segment data forwarding mechanism is adopted.The paper designs an appropriate feedback retransmission mechanism to ensure the efficient and accurate transmission of segmented data aiming at various abnormal conditions in the process of data transmission.Compared with the standard protocol stack of segment data forwarding mechanism and feedback retransmission mechanism,the proposed data forwarding mechanism and the corresponding feedback retransmission mechanism obtain low communication delay of the same data in the better channel condition.MRF24J40 MC transceiver modules networking in Microchip company verifies the above research content and the improved scheme.The results show that the new data transfer mechanism proposed in the power balance of the network node,quick access to link key scheme,automatic transmission segment data forwarding and the corresponding feedback retransmission mechanism can effectively improve the system performance. |
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