Filtered Multitone Modulation Systems, Methods And Technology Research To Reduce Inter-symbol Interference (isi)

To ensure prospective reliable high-speed and wideband wireless mobile communications, multicarrier modulation technique has recently evoked considerable interests and widespread applications for its attractive qualities in resisting multi-path effects and mitigating ISI. Taken as an example, the OFDM technique has been adopted for some formed standards. However, OFDM has some intrinsic shortcomings: its orthogonality is susceptible to be destroyed by frequency offset in practical transmission, thus considerable overheads (CP and virtual carriers), strict synchronization and etc. are needed to guarantee it. In order to avoid these disadvantages of OFDM, a new orthogonal multicarrier modulation technique, named Filtered Multitone Modulation (FMT) is studied for its applications in wireless communication in this thesis, with some related aspects being investigated intensively.In this paper, to introduce the background and purpose of research efforts on FMT's application, the transmission character of mobile wireless channel, latest research developments in wireless communications and potential problems in OFDM are firstly discussed. Second, the principle of FMT and its efficient implementation is particular studied from its basic idea and system model. Then, Based on the analysis of ISI caused by FMT system, MMSE-DFE in FMT system and its efficient implementation are brought forward; and THP, improvement of DFE, is introduced to take the place of DFE in FMT to cancel ISI. The performance of DFE and THP in FMT is compared by simulation. Finally, the performance of channel coding and trellis shaping in FMT system based on THP is studied in the circumstance of band limitation. The traditional error-control coding technique's great disadvantage is confliction between reliability and efficiency. Since the ability of error-correction is obtained at the expense of adding redundance, the loss of bandwidth is inevitable. Combination of trellis shaping and channel coding can solve the problem. In this paper, we combine trellis shaping with THP in FMT system and study the gain caused by trellis precoding. The performance of FMT using MMSE-DFE, THP and Trellisprecoding are given by simulation in AWGN and Raileigh channel. Compared with uncoded QPSK scheme, trellis shaping achieves a coding gain and a shaping gain, increases FMT system's performance without reducing information transmitting speed or expanding bandwidth. This will help to FMT scheme practical.