| With the extraordinarily rapid development of information technology, WSN(Wireless sensor network) technology owes broadly application prospect in domainsof agriculture, industrial, bio-medical treatment and military defense. However mostdomestic indoor environmental monitoring methods is still manual measurement orwired monitoring system, it requires a lot of wiring, not only time-consuming andincrease the cost, but also need re-arrangement of the line to the whole system whenthe monitoring of region changes. It brings much inconvenience, so how to make theindoor environmental monitoring methods more convenient and effective is moreimportant.In this paper, WSN is introduced to indoor environmental monitoring, and anoverall design scheme of environmental monitoring system is proposed based on itscharacteristics of wireless transmission and flexible deployment. The hardware ofnodes is designed based on CC1100wireless transceiver and ATMEGA88microcontroller, and show the detailed characteristics of the two chips. In software,the workflow of the sensor node and sink node is analyzed at first, then the node isdesigned by module, and the design of serial communication part is added in sinknode. In addition, the data acquisition system is also designed to achieve theprocessing of data collection. When an alarm condition occurs, the alarm informationwill be displayed in the interface of the system, and the users can find in time. Thehistorical data can be queried and alarm threshold can be set. The most importantthings is that the binding relationship between node and location can be changed whenthe monitoring of region changes, it can avoid the inconvenience from the wiredsystem. Finally, the nodes are deployed in the field, the small test net work is set up tothe system, and the results are satisfactory.The assessment of the link quality is particularly important to WSN. Firstly,analyze the three commonly used link quality evaluation factors: packet reception rate,received signal strength and link quality indicator, and describe the shortcomings anddeficiencies. In order to get a more accurate link assessment model, the correlationbetween the distance, power and packet reception rate is analyzed on the basis of alarge number of measured data, and get the curve model by curve fitting, thenaccording to the two models, a three-dimensional model of link quality evaluation based on the distance and power is proposed by SPSS software, and verified byexperiments. The model can infer the packet reception rate or link quality betweennodes from the distance and transmit power and reduce the consumption of thenetwork, it also provide valuable reference for practical application of WSN and thesimulation study of wireless links. |
