Two-dimensional Spread Spectrum Communication, Research, And Its Anti-jamming Technology

Multicarrier wireless communications have been widely investigatedrecently, and two dimensional spread spectrum technology spreads theoriginal signal in time and frequency domain simultaneously, which is theextension of traditional direct sequence spread spectrum and multicarrierspread spectrum. This dissertation will propose two methods which canfully utilize the time-frequency spread spectrum structure to implement2D-SS over fading channel, one is pilot symbol assisted coherentdetection and the other one is time-frequency chip-level differentialdetection. The theories and algorithms for the spread spectrum system toresist wideband interference have also been deeply discussed in thisthesis.First we introduce the characteristics of multicarrier wirelesscommunications and the research background of two dimensional spreadspectrum, and then summarize the questions to be further studied.2D-SS system under fading channel will be studied in the 2nd part ofthis dissertation. There aren't many researches in this field, all theexisted results are based on AWGN channel or on that the channelparameters are already known, and the study of 2D-SS non-coherentdetection method is still weak. In this paper, we propose two practicable2D-SS schemes, one is pilot symbol assisted coherent detection whichadds the pilot symbol and the data symbol orthogonally, another one ischip-level time-frequency non-coherent detection precedes with a briefintroduction of the merits of chip-level differential detection. The BERperformance of these two schemes over multipath fading channels areanalyzed and compared, the results indicate that time-frequencychip-level differential detection is capable of resisting time and frequencydual selective fading, and is better than the coherent detection schemeproposed in this thesis in the time frequency dual selective fadingchannel.Spread spectrum communications is well known by its anti-jamming...