Research On Mai Suppression Technique For Single Access Link Of TDRSS

TDRSS means Tracking and Data Relay Satellite System.Only a few data relay satelltes can cover almost all the low orbit,and TDRSS can improve efficiency and reliability of data transmission.And the mechanism of how TDRSS work can achieve continuous and real-time high-speed communication between multiple targets and ground station,which can make up the low orbit coverage and high construction cost of space measurement and control system based on ground station and ocean tracking ship.With the rapid development of space technology,there are more and more spacecrafts in space.So a large amount of data and information need to be transmitted between the spacecrafts and ground station based on TDRSS.Therefore,it will inevitably lead to interference between signals,especially MAI(multiple access interference).As for single access link of TDRSS,measurement and control of multiple targets is usually used in data transmission of multiple targets users,such as rendezvous and docking and satellite constellation and so on.Currently,the single access of TDRSS in s-band can serve up to 12 users,and this research is all about how to eliminate the impact of MAI,increase the system capacity,and achieve the reliable and accurate transmission of data.This thesis is based on DS-CDMA(Direct Sequnce-Code Division Multiple Access)communication system of TDRSS to discuss the MAI suppression technique for single access link of TDRSS.The main works are as follows:Firstly,the communication network model of TDRSS is introduced,the model and principle of the single access link for multiple targets of TDRSS are introduced.And basic theories of DS-CDMA system are introduced,especially the structural model of the transmitter and receiver of the system and the main performance indexes.And the principle and influence of MAI are discussed.Secondary,several kinds of MAI suppresion technique are discussed and simulated,mainly including the selection of spread spectrum sequences,the power control technology,multi-user detector(MUD):decorrelation detector and minimum mean square error(MMSE)detector of linear multiuser detection technology,successive interference cancellation(SIC)detector and parallel interference cancellation(PIC)detector of non-linear multiuser detection technology.Through the simulation experiment,several methods are verified to prove the performance and effect of suppression of MAI.Thirdly,combined the several kinds of MAI suppression tecnique,a method to suppress MAI for single access link of TDRSS is designed.Setting up the interference cancellation detector feedback loop to constantly suppress multiple access interference between the targets.Through simulation experiments,the performance of the method is verified and the feasibility is proved to suppress MAI effectively.