Modeling And Analysis Of Transmission Performance Of Space Information Networks

Space Information Network(SIN)is based on space platforms that can sense,acquire,process and transmit space information in real time large-scale network system.As an important space infrastructure in our country,in order to better provide communication services for application requirements including ocean voyage,emergency rescue,navigation and positioning,air transportation,aerospace measurement and control,etc.,it is urgent to fully explore the internal relationship between network parameters and network performance,so as to further explore the relationships of network performance with network parameters,and use this as the guiding basis for network performance optimization.Due to the large number of inherent communication nodes in SINs,the large differences between inter-satellite and satellite-ground links as well as the large-scale temporal and spatial two-dimensional changes of nodes and links may lead to heterogeneous traffic and link as well as time-varying connections,and may make the precise modeling and performance analysis of the network become more difficult.Therefore,how to accurately evaluate the carrying capacity of the SIN,formulate network service characteristics and various resources,and reveal the relationship between network performance and network service configuration parameters are major and key issues in the process of current SIN development research.This dissertation exploits the queuing theory and stochastic network calculus as mathematical tools and theoretical foundations,and is committed to starting from the modeling and analysis of network single-node satellite,studying the operational mechanism of its traffic arrival process,storage process,transmission process and departure process.Moreover,the dissertation gradually expands the network scenario to cascaded dual-satellite communication scenarios and complex multi-satellite heterogeneous network scenarios,analyzes the impact of homogeneous,heterogeneous traffic arrival processes and link transmission services on network performance,and reveals the theoretical relationship that the network performance is configured with network service parameters.The specific research contents and innovative results of this dissertation are summarized as follows:1.Aiming at the problem that the traditional vacation-based queuing model cannot be directly applied due to the fact that the intermittent transmission process between communication entities in the SIN is not affected by the queue status,an M/G/1 queuing model based on limited service time is proposed,which realizes the effective decoupling of the intermittent transmission process and the queue status,and improves the matching of the model and analysis with the actual system.In this regard,this dissertation proposes a time-limited M/G/1 queuing model to characterize the traffic acquisition,storage,forwarding,and departure processes of the single-node satellite.On this basis,by introducing a transient analysis method based on the queue status,the end-to-end performance of the SIN single-node network is evaluated from the perspectives of average queue length and average waiting delay.Besides,according to the fact that the second-order digital feature of the deterministic service process is zero,which is a special case of the general service process,here the Laplace transform of the deterministic service process is brought into the calculated network performance expression revealing the relationship between the network performance indices and network configuration parameters so that the closed-form expression of the lower bound of the network performance index is obtained.Through a lot of Monte Carlo simulations,the simulation results prove the correctness and effectiveness of the modeling and performance analysis methods proposed in the SIN single-satellite scenario.In addition,by reasonably designing the length of the run time of the simulation,the critical value of link utilization can be determined under the condition of ensuring that the system is stable.The above analysis can provide an important and intuitive theoretical basis for the memory size design of the satellite node in the SIN and the configuration of network service parameters such as the power and bandwidth allocation of the transceiver.2.In view of the problem that the traditional Poisson-based traffic model cannot accurately describe the traffic characteristics caused by the random dynamic characteristics of multimedia traffic(e.g.,the ON/OFF characteristics of image data),and the problem of traditional G/G/1-G/G/1 model cannot accurately model the intermittent transmission process of modular cascaded satellites,considering the relationships of traffic arrival and transmission,a Markov chain-based MMOO/MMSP/1/K-G/G/1 cascaded queuing model is proposed to more accurately describe the Markov property of multimedia arrival and the discontinuity of the cascaded transmission process.Among them,the Markov modulated ON/OFF(MMOO)traffic arrival model can describe the Markovian property of the multimedia traffic inflow more accurately than the traditional Poisson model.In the procedure of the modeling process of the Markov modulated service process(MMSP)based intermittent inter-satellite transmission process,a Monte Carlo Markov chain-based inter-satellite link availability and unavailability matching algorithm is proposed so that the steady-state distribution of the Markov chain can accurately match the random distribution of the available period and the unavailable period of the transmission link by constructing a Markov chain.On this basis,an algorithm for determining the number of sub-states subject to the duration of the available and unavailable periods is proposed to guarantee that the residual time in each state approaches its actual time length.This algorithm can make the system residual time in each state approach its actual length of time.By solving the steady-state probability distribution of the system,the theoretical expressions of the average packet loss rate,average queue length,and average delay of the first-level queue are derived.Due to the influence of the non-Markovian property of the first-level queue leaving process on the second-level queue arrival process,this dissertation uses the classic G/G/1 model to evaluate the performance of the second-level queue,thus making the analysis process of the whole end-to-end link transmission easier without losing accuracy.The simulation results verify the effectiveness of the proposed method and highlight the impact of the number of multimedia traffic sources,burst characteristics and satellite memory size on the performance of SIN.3.Aiming at the problem that the heterogeneity of traffic arrival process and transmission service process is difficult to be characterized and analyzed when multiple user satellites with heterogeneous traffic perform data back-transmission through heterogeneous links,a moment generating function(MGF)based min-plus convolution and Monte Carlo Markov chain respectively solve the characterization problem and delay performance analysis problem of the transmission service obtained by heterogeneous traffics in heterogeneous links.In this regard,we first establish a series-parallel queuing model containing heterogeneous services to simulate the data offloading process of the user satellite.This dissertation introduces the MGF containing all the information of the distribution moments of the traffic,and uniformly represents the heterogeneous traffic to describe the characteristics of heterogeneous services.We propose a min-plus convolution method basing on stochastic network calculus and a Monte Carlo Markov chain method to determine the residuals of specific services in the serial and parallel queuing processes that describes the process of heterogeneous transmission services.This dissertation eliminates the influence of heterogeneity,derives the network basing on the geometric relationship between the traffic arrival envelope,the remaining service envelope,and the system average queue length and delay,and further derives the closed-form expression of the upper bound of the stochastic delay.The simulation results verify the effectiveness of the proposed analysis method,and further reveal the highly differentiated delay characteristics of heterogeneous traffic in heterogeneous links.