Study Of Coding And Decoding Technology And Methods For Reservoir Regime Monitoring Based On Satellite MIMO Transmission

In the system of cascade hydrocomplex for Three Gorges-Gezhouba Dam,reservoir cascade and risk analysis will be studied. Thesis studies how such regime data needed by decision analysis are transmitted from remote monitoring station to dispatching center correctly and timely through satellite MIMO(Multi-Input Multi-output) wireless transmission mode. During the transmission channel,it analysies effective algorithms of signal coding, decoding and channel precoding,which provides foundation for cascade hydro-junction.Currently,many large reservoir cascade systems in domestic and international countries select satellite communication for regime forecasting,because satellite communication can realize many unattainable functions by other wireless communications. For satellite communication system, MIMO technology can increase transmission speed of regime data and accuracy of transmission system substantially.MIMO technology improve much better in effectivity and reliability than single-input single-output(SISO) system.MIMO technology configures multi antennas both in transmitter and in receiver.It introoduces concept of space-time block coding(STBC),so signals can be transmitted in multi space and multi time slots and fulfill spatial multiplexing and diversity gain.So this thesis choose satellite-MIMO transmission system.First,this thesis defines communication means, explains network struture in groud station and spatial station,analyzes network transmission model of reservoir cascade dispatch information for Three Gorges-Gezhouba Dam and satellite-MIMO model and satellite channel model.Then according procedure of wireless data transmission,thesis analyses each module and modifies some algorithms. Detailed researches and major contributions of this dissertation are presented as follows:1.For single-user satellite-MIMO system,in transmitter,thesis analyses three methods of space-time coding suitable for transmission in satellite channel:orthogonal space-time block coding(OSTBC),Quasi-orthogonal space-time block coding (QOSTBC) and Bell Labs Layered space-time(BLAST).Under the same channel state,modem type and number of iterations,three coding methods are thoroughly analysed and simulated.Based on these studies,thesis improves coding algorithm as VBLAST-QOSTBC.It gives specific coding algorithm.Its conclusion comes from computer simulation.Results show that new joint coding decreases BER of single-user satellite-MIMO system and its diversity gain remain invariant.2.In receiver,thesis analysed detecting technology of satellite-MIMO system. MIMO detecting is classified as linear detecting and non-linear detecting. Linear detecting algorithms are simple and operation complexity is low,but their performance is poor. In non-linear detecting technology,SIC and PIC realize discrimination and detecting of datastream of each layer by method of successive detecting interference cancellation and add close-loop feedback loop,their performance is better than linear detecting.ML detecting lists all the values of transmitted symbol according to numbers and values of modulated signals,then decodes them according to maximum likelihood criteria.Its performance is the best,but operation complexity is high.3.In Wireless channel,thesis analyses transmission scheme for satellite-MIMO system according to whether transmitter and receiver knows the channel state information.Then it studies several types of precoding methods.Based on these,thesis improves four algorithms for combining precoding and detecting,and compare their BER performance.Algorithm1(QR/LQ/SQRD/SLQD-SIC, QR/LQ/SQRD/SLQD-OSIC) studies joint precoding and detecting improvement algorithm by combining QR/LQ decomposition with PIC detecting in system.Existing QR/LQ decomposition and their sorted form-SQRD,SLQD precoding,can produce better performance in BER and complexity.Thesis combines QR, LQ, SQRD, SLQD with SIC and transmits symbols.Then Thesis combines four precodings with OSIC and transmits symbols.It compares BER of these precoding methods. Simulation shows these methods are better than corresponding single precoding.Algorithm2(QR/LQ/SQRD/SLQD-PIC) studies joint precoding and detecting improvement algorithm by combining QR/LQ decomposition with PIC detecting in system.PIC need not sort user power and it can detect signals of each layer for every user concurrently,so its detecting delay is less than SIC and its performance and complexity is similar to SIC,sometimes even better than SIC. Thesis combines QR, LQ, SQRD, SLQD with PIC and transmits symbols.Its BER performance is a little worse than Algorithm1.Algorithm3(ML-PIC) studies joint precoding and detecting improvement algorithm by combining PIC precoding with ML detecting in system. For ML is the best detecting algorithm and PIC has a good performance,so they’re combined.Thesis gives their specific model and simulate.The result shows its ber performance is better than algorithm2and algorithm l,but its complexity is high.So it should be selected by requirement.Algorithm4(GMD-THP-SIC,GMD-THP-OSIC,GMD-THP-PIC) studies joint precoding and detecting improvement algorithm by combining GMD-THP precoding with nonlinear detecting in system,including GMD-THP-SIC,GMD-THP-OSIC, GMD-THP-PIC. Thesis gives their specific model and procedure.Simulation shows their performance is better than algorithm3and better than former algorithms.4.Thesis applies somg improved algorithm to the examples of regime monitoring system of Three Gorges-Gezhouba Dam,and design the transmission procedure.In receiver,regime data is received and BER is computed.The innovations of thesis include:①Satellite MIMO wireless transmission mode is applied to regime monitoring system;②The tranmitting signals in Satellite MIMO are coded by QOSTBC-VBLAST(Quasi-Orthogonal Space-Time Block Code-Vertical Bell Labs Layered Space-Time),so realizes tradeoff of diversity gain and multiplexing gain;③Several channel precoding methods are improved and improved BER(Bit Error Rate), performance of system.In Chapter1,thesis analyses significance of the subject.Chap.2studies network of regime monitoring. Chap3.analyses and improves space-time coding method of transmitting signals.Chap.4analyses detectind and decoding algorithm in receiver. Chap.5analyses typical channel precoding algorithms, improves four precoding-dectecting joint algorithms and gives simulation diagrams.Chap.6gives an example for regime data transmission based on satellite MIMO. Finally,in Chap.7,thesis gives a summary and forecast for research worlk.