Research And Design Of Data Acquisition System For Smart City Based On 6LoWPAN

Under the trend of the global urban construction to the wisdom of the direction of development,China has also joined the wave of smart city construction.By analyzing the characteristics of the system architecture of the smart city and the practice cases at home and abroad,and aiming at the basic demand of the urban data in the construction of the smart city,a smart city data acquisition system based on6 LoWPAN wireless sensor network technology is researched and realized for the city of data acquisition,transmission,storage and management,mainly to complete the following four elements.First of all,the underlying network of data acquisition system for smart city is designed and implemented.The advantages and disadvantages of wireless network technology such as 6Lo WPAN,WiFi and Sub-GHz are analyzed and compared.And combined with the characteristics of large-scale of the data acquisition system,the underlying network of data acquisition system for smart city based on large network capacity of 6Lo WPAN technology which adopts IPv6 addressing is designed.The network coordinator,network router,data acquisition terminal and so on which constitute the underlying network of data acquisition system for smart city are studied and realized.In the hardware design,the data acquisition terminal adopts the modular design to improve the hardware reuse rate.In the software design,through the C/S way to achieve efficient data acquisition and transmission at the on-site sensing layer of data acquisition system,which improving the flexibility.At the same time,effectively improve the data flow ratio.Secondly,the integration of 6Lo WPAN network and Internet is studied and implemented.In order to solve the problem of existing fusion method,for example,the adaptability of network convergence based on application layer custom protocol is poor,the network convergence is not practical through network connection based on pure IPv6 network,the network integration based on NAT-PT required in theprotocol conversion and address translation hardware resources on a large overhead,and will take up too many IPv4 address.The fusion method of 6Lo WPAN network and IPv4 network based on 6to4 tunnel is studied,which can effectively reduce the occupation of IPv4.Furthermore,the embedded gateway is designed based on 6to4 tunnel and Netfilter framework,and the performance of the embedded gateway is tested.The test results show that the average forwarding delay of the packet is18.15 ms,which is less than that of NAT-PT(41.5~44.5ms),and has a small packet loss rate.Thirdly,we design and realize the data management and service platform for smart city with data acquisition and management,data storage and management,and data service management.Through the design of data collection rules,data acquisition drivers,data collection equipment online management,to achieve a variety of data collection and equipment management.The data storage and management problem of the smart city data acquisition system is solved by using the Hadoop distributed system's powerful ability to store and deal with the data.At the same time,the data service is encapsulated by the data model,so as to realize the security and accurate service of the data application.Finally,the smart city data acquisition subsystem is tested and verified by the data application,namely the urban street light monitoring system and the atmospheric environmental monitoring and early warning system.It indicates that system is feasible and easy to maintain and extend.