Research Transmission And Fusion Mechanism Of Connectivity Parameters In Opportunistic Sensor Networks

OSNs(Opportunistic Sensor Networks) have some significant features such as long delay, limit energy and intermittent connection. And network connectivity parameters are important to evaluate the connectivity of networks. Due to the amount of network connectivity parameters is lager, and sensor node energy is limited, it is important to decrease the transmission of network connectivity parameters. This thesis is supported by the national natural science foundation of China-Research of OSNs connectivity supervision(NO. 61262020), and it mainly focus on data fusion and transmission of network connectivity parameters.This thesis summarizes the development of OSNs. And it introduces the data compression mechanism of WSN(Wireless Sensor Networks) and the routing algorithm of ONs(Opportunity Networks) and CONs(Community Opportunity Networks). Through analyzing the character of OSNs connectivity parameters and the disadvantage of wavelet transform, this thesis proposes data fusion schema for opportunity sensor networks connectivity parameters based on biorthogonal wavelet(DFBW). DFBW decomposes firstly network connectivity parameters in biothogonal wavelet based on the attributes of connectivity parameters. It chooses wavelet coefficients based on hard thresholds, and it quantifies the wavelet coefficients with the method of scare quantization. Finally, it uses Huffman coding to encode the low frequency wavelet coefficients, and it uses Sharing run length code to encode the high frequency wavelet coefficients. The DFBW uses the two norms to control the precision of reconstruction.Through analyzing the characters of multi-area opportunity sensor networks, this thesis proposes Transmission Mechanism for the connectivity parameters of OSNs based on Utility function(TMU). TMU constructs the utility function based on the history delivery ratio of mobile node(Ferry) and the probability that Ferry encounters the Sink. Whether messages of connectivity parameters are forwarding to Ferries or not is based on the utility value of Ferry when Ferry encounter each other. When an area node meets a Ferry, the area node forwards directly messages of connectivity parameters to the Ferry. The area node forwards messages of connectivity parameters to Ferry with the high utility value when an area node encounters many Ferries. When Ferry meets some area nodes, the order of area node forwards messages of connectivity parameters to Ferry is based on the urgency of area node. When area node encounterseach other, the forwarding of connectivity parameters messages is based on the counts that the area node has met Ferry.According to the simulation results, the thesis decides the precision of reconstruction, the lower bound that DFBW deal with discrete series of connectivity parameters, and the weights of the factors that have an effect on the utility of Ferry.This thesis inspects the performance of DFBW and TMU with different message TTL(Time To Live), the number of Ferry and the amount of connectivity parameters.The results of simulation show that the number of Ferry and TTL have an effect on message delay and utilization ratio of network resources in TMU, the DFBW decreases the amount of transmission, and it saves network resources.