Multiple Access And Synchronization Technology Research Of FMT System

Filtered Multitone Modulation(FMT) is a new multicarrier technology in contrast to Orthogonal Frequency Division Multiplexing(OFDM) technology.In FMT systems,the spectrum of each subchannel has a high level of spectral containment.So the Inter Channel Interference(ICI) of FMT system is negligible compared to other forms of interferences,while it often appears in OFDM system because of its sensitivity to frequency offset.Therefore,subchannel equalization is seeded in order to reduce the remaining ISI introduced by the filter banks and transmission channel.The paper does some research mainly from three aspects based on the basic principle of Filtered Multitone Modulation technology.Firstly,this paper deduced the average C/I ratio's quantitative formular expression by analyzing the received signal after demodulation under different fading channel conditions.By comparing and analyzing OFDM and FMT system's performance it indicate that OFDM system outperform FMT system over slowly time-varying fading channels with low doppler frequencies while it's opposite over highly frequency-selective fading channels with high doppler frequencies.Secondly,from the point of view of Multiple Access mode in multicarrier technology this paper classified FMT system into Time Division Multiple Access FMT(FMT-TDMA),Frequency Division Multiple Access FMT(FMT-FDMA) as well as Code Division Multiple Access FMT(FMT-CDMA) and finally made a series of performance analysis for FMT-FDMA system.The result indicate that FMT-blockFDMA outperform FMT-interleavedFDMA and non-critically sampled FMT outperform critically sampled FMT under same conditions.Thirdly,this paper discussed time synchronization and frequency synchroniza -tion technology of multicarrier modulation system,applied one kind of training sequence-based iterative synchronization algorithm to FMT system and used pseudo random sequence's good correlation characteristics for the iteration and estimation of each user signal's time delay and frequency delay.The result indicate that after a small number of iterative calculation,the algorithm can accurately reconstruct data by using short training sequence.Finally,the research in this paper prove that FMT technology could work well in wireless environments.