Link Quality Evaluation Algorithm Based On Rssi And Lqi And Application In Wireless Sensor Networks

Wireless sensor network, which is application as centric provides the interaction method with the physical world. On the one hand, the application always require high end-to-end reliability; On the other hand, the underlying wireless communication link is extremely unreliable due to the influence of various factors, and meanwhile, system resources especially the energy resources are particularly limited. These factors become a bottleneck as the wireless sensor networks moves toward the laboratory to the practical application which must be broken through. Therefore, how to satisfy the requirement of high reliability and actualize energy-efficient data transmission becomes a key problem and hotpot.Estimation of link quality is vital in any self-organizing network, wired or wireless, since routing paths should never be constructed over poor links.The traditional method of link quality evaluation always takes the packets reception rate as the evaluation parameter in underlying wireless communication link. Though the assessment results are accurate, each node needs to periodically sent detection packets, in order to assess the quality of communication between it and neighbors, when the network nodes are high density,the network will lead to a greater cost. Though the correlations of average RSSI, average LQI and the packet reception rate,this thesis founds:the relativity between average LQI and packet reception rate is high as 91.8 percents, and the relativity between packet reception rate and average RSSI is about 55 percents. Therefore, the average LQI can be the main parameter of link assessment, and the average RSSI can be used as auxiliary evaluation parameters. Compared to packet reception rate both evaluation parameters could reduce costs, and save energy consumption.This thesis first analyzes several communicate factors which lead the underlying wireless communication link unreliable, through a large number of the actual measurement in underlying wireless communication link, characteristics of unreliability, variability and non-symmetry, etc.in underlying wireless communication link are validated. Extracting the characteristic parameters LQI and RSSI which reflect link quality, and analyzing and modeling the relationship between the characteristic parameters, then get the evaluation model of it. Addressing the reliability and non-symmetry of the underlying communication chain, and analyzing the shortcomings of the traditional measurement of a single routing for wireless sensor network routing protocols, we bring forward routing measure IETX methods which is based on RSSI, the ETX LQI.This measuring method is applied to the AODV agreement, and validates the agreement with the actual measurement. Finally, the measurement data is analyzed, compared and evaluated. Test results show that IETX-AODV is better than the original measurement method based on the routing performance in throughput, packet loss rate, as well as on energy efficiency.