| Agriculture is the basic industry of the national economy.The Agricultural Internet of Things is one of the important ways to develop modern agriculture,and has a far-reaching and positive impact on the development of agricultural economy in China.In the Agricultural Internet of Things,the perception layer collects the information and transmits it to the application layer through the transport layer.After the decision is made,the transmission layer is transferred to the perception layer to control.The transmission of information in different layers requires energy saving and accuracy.In response to this demand.In this paper,energy saving measures are adopted to reduce energy consumption.In terms of accuracy,the message push mechanism is applied to Agricultural Internet of Things,use the MQTT protocol to push the sensed data and through improving the message push server to improve the performance of the server,and ensure the accurate arrival of the message.Aiming at the above key technologies of Agricultural Internet of Things,the main research contents are:1.Traditional transmission of multiple sensor data use a decentralized packet format,which will lead to excess energy consumption.In view of this problem,a plurality of sensor data is encapsulated and sent uniformly by setting a data packet,thereby avoiding the energy consumption required to start the wireless unit several times when transmitting a plurality of sensing data.The experimental results show that under the same amount of power,the data can be sent more than 1.9 times by using the self-designed data packet to transmit the data to the integrated sensor nodes than before.The results show that the energy saving measures are effective.2.In aggregation gateway node,if the data of multiple terminal nodes is pushed directly,the energy consumption caused by the number of push will be increased.In order to solve the problem,it uses Huffman encoding compression mechanism to compress data from a plurality of terminal nodes,the compression rate is about 41%,then pushed.The experimental results show that under the same amount of power,the compression mechanism can push about 25.31%packets,namely,unit push message energy consumption is smaller.3.In order to further improve the running performance of the server.To improve the performance of message push servers,the free management connection mechanism and the message send topic match mechanism are optimized respectively of the servers.In the free management connection mechanism,build the indexes for the free connection which save the connection object of the original array,and use a dynamic array to save the indexes.When the new connection comes,it can quickly find the free connection through matching the index,which avoids the waste of resources for the comprehensive scan of the original.In the message send topic match mechanism,use the hash table to save the topics and the mapping address between them and their subscription lists.When operating on the topic,it does not have to scan the entire subscription tree or traverse the same topic to find the subscription list,can quickly find the subscription list through the mapping address of the topic in the hash table directly,this improvement avoids the problem of taking too long processor-time for a full scan of the subscription tree when operating on a topic.Experimental results show that the average server response time of the improved method is 13.916%higher than the previous method.It shows that the improved method can effectively improve the performance of the server.Based on the above related technologies,the terminal collection node and the convergence gateway are implemented by software and hardware,and a greenhouse monitoring platform is built for comprehensive testing.The platform realizes the complete process of collecting,transmitting and pushing the greenhouse environment information.Through tests,we found that under the same amount of power,we could push more 42.6%of the data packets than before. |
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