Research On Stochastic Petri Nets-Based Performance Analysis Of Satellite Networks

Based on the state-of-the-art of satellite network and its models, in this thesis we have analyzed the modeling methods for satellite network and the common methods for performance analysis of networks by comparison. The feasibility of physical experiment of satellite networks is slim because of the expensiveness of satellites and so on, making the combination of simulation with diverse mathematical models be the best choice for obtaining better performance. Modeling and simulation have been used t o s tudy t he p erformance o f s atellite n etworks, w hich o ffers u seful g uide a nd reference for the construction of satellite networks.At home and abroad, current tools for the performance evaluation of satellite networks are mainly based on queue theory and Markov process. Unfortunately queue model lacks the ability to model the relatively complicated structures in satellite networks such as parallelism, asynchronization and distribution of the message traffic in the satellite networks, as well as Markov process is hard to model the corresponding level of stochastic process. In contrast, SPN (Stochastic Petri Nets) is more powerful in the ability of description and also convenient to model the Markov process. Consequently, SPN is adopted to model and analyze satellite networks in this thesis.Some earlier investigations have been focused on a class of satellite networks usingSPN m odels b y assuming t hat p rocessing d elay, p ropagation d elay and packet 1 oss would be negligible. However, for actual satellite networks, the effect of packet loss and time delay can't be neglected.The need for improving the quality of modeling and analyzing, we then improve the SPN modeling and analyzing of satellite networks by taking average time delay of message transmission and packet loss during communication into account.We have mainly engaged on following original works:(1)The relevant theory about the calculation of packet loss probability is proven.(2)Considering the effect of packet loss, GSPN (Generialized Stochastic Petri Nets) models have been constructed to analyze the average time delay and packet loss probability of LEO (low earth orbit) satellite networks under half-duplex mode and full-duplex mode with SPNP (Stochastic Petri Nets Package) 6.0, respectively.(3)Considering the effect of packet loss, a SRN (Stochastic Reward Net) model is constructed to analyze the main factors in packet loss probability of LEO (low earth orbit) satellite networks with SPNP 6.0.(4)The GSPN model of a triple-layered LEO/MEO (medium earth orbit)/GEO (geosychronous earth orbit) satellite network is constructed, and employed to evaluate the network performance with SPNP6.0 software package. The effectiveness of the results obtained by GSPN-based analysis is further verified in comparison with these by network simulation using OPNET (Optimum Network Performance), and some new results, such as the performance of the triple-layered network is better than that of the LEO one under high load, are derived thereby.