Research On Key Technologies Of Adaptive Transmission And Networking In Space-Terrestrial Integrated Network

As the rapid development of rocket launching,satellite platform and payload technology,Space-Terrestrial Integrated Network(STIN)has attracted worldwide attentions.STIN means to link the satellites with different orbits,types and functions and the corresponding ground facilities to work together through the inter satellite and the satellite ground links,so as to realize the efficient interconnection of information.It has wide application prospects in terms of maintaining and expanding national core security interests,emergency communication,wide area IoT,deep space exploration,and so on.STIN has several characteristics including high throughput requirement,large dynamic range,low bit error rate,large signal-to-noise ratio fluctuation,large propagation delay,limited resources,dynamic topology change and poor flexibility.These characteristics require adaptive data transmission and networking technologies to the environment.Based on the keyword of ―adaptive‖,this dissertation focuses on the key technologies of the adaptive transmission and networking for STIN.The innovations are as follows:1)To meet the requirements high throughput and large dynamic range with the constraint of limited storage resources,a Quasi-cyclic Low Density Parity Check Code(QC-LDPC)decoder based on compact storage is proposed.Firstly,a compact storage method is designed to store the extrinsic information the hard decisions.Then,based on this method,a QC-LDPC decoder architecture is designed,which can dynamic adjust the parallelism of processing units.The architecture applies a fine-grained multi-level pipeline method to realize the main processing units.Then,the key performance such as the memories,throughput and bit error rate of the decoder are analyzed theoretically and simulated.Finally,the experimental results verify the correctness of the analysis and show that the proposed QC-LDPC decoder can adjust the throughput adaptively and reduce memory resources more than 20% while improving the throughput.2)To solve the large fluctuation of Signal to Noise Ratio(SNR)problem with the constraint of limited storage resources in STIN,a matrix transformation algorithm based DVB-S2 LDPC decoder is designed and implemented.Firstly,a new matrix is obtained by transforming the parity check matrix of DVB-S2 LDPC code,which is composed of QC submatrix and RTD submatrix.Secondly,based on QC-RTD matrix,a DVB-S2 LDPC decoder architecture with throughput and rate adaption is designed.For this architecture,both storage method of RTD matrix compatible with QC matrix and design method of rate compatible processing unit are designed.Thirdly,key performances such as the memories,throughput and bit error rate of the decoder are theoretically and simulated.Finally,extensive simulation results are given,which coincide with the theoretically analysis.Implementation results show that the proposed dynamic DVB-S2 LDPC decoder can not only realize the throughput and rate adaption but also reduce memory resources more than 33%.3)To solve the problems of low throughput and large delay in STIN,a combination of block Acknowledgement(ACK)and Adaptive Coding and Modulation(ACM)based Multiple Access Control(MAC)protocol is proposed.Firstly,the basic idea of the protocol is that the sender transmits data frames to the receiver in consecutive time slots,and the receiver confirms the frames at one time.According to the success rate of the transmission,the sender adaptively adjusts the size of time slots as well as the modulation and coding scheme in the next time frame.Furthermore,the proposed MAC protocol is modeled mathematically,and closed formulas of the average delay,throughput and retransmission times of the system are derived.Finally,simulation results verify the correctness of the theoretical analysis,and show that the designed MAC protocol can not only improve the throughput but also reduce the delay of STIN.4)To solve the problem of limited observation time and low the efficiency of existing satellite routing algorithms,a multi-orbit satellite formation networking method and a configurable routing algorithm based on forwarding rules are designed.On the one hand,the proposed method allows multiple satellites to form a satellite formation on multiple orbits to realize the earth observation in a coordinated manner.On the other hand,a configurable routing algorithm based on forwarding rules is designed for satellite networks.The routing results of this algorithm can be calculated by using centralized controller or distributed method for each satellite node.Specifically,according to the current networks topology,the algorithm calculates the routing path based on the configured forwarding rules.The simulation results show that the proposed method and algorithm efficiently adapts to the dynamic topology changes to improve the observation time and system throughput.Moreover,for the problem of poor accessibility and flexibility for controlling in STIN,this dissertation explores the corresponding networks architecture and designs a architecture based on the software defined networks for STIN(SDSN),which can adjust and control the decoder,MAC protocol and routing algorithm designed in innovation 1-4 according to the networks scenarios.