Filtered Multitone (fmt) Modulation System Wireless Simulation Platform And Key Technology Research

With the progress of the world, people need high quality and transmission rate of communications, and simple voice service can't meet the requirement It is possible to get multimedia service with wireless network at anytime and any places, for that electronic, multimedia and mobile communication has developed rapidly. Up to now, 3G has been launched into business in many countries, and researches are focus on the next generation communication system, called 4G, which is characteristic of the good resistance to multipath decay and high efficiency of frequency. The data rate of 4G is ranging from 10Mbps to 100Mbps.Multicarrier technique provides high data rate and efficiently avoiding intersymbol inference (ISI) arosing by multipath propagation. As one of the multicarrier techniques, OFDM has many advantages, such as high data rate and resisting multipath decay, and it has become a hot field in the researches of 4G. On the other hand, there are many problems of OFDM, for example: high sensitivity to frequency offset and great peak to average power ratio (PAPR), etc. All these issues restrict the applications of OFDM in wireless environments to some extent, so lots of researchers pay attention to them.Comparing to OFDM, a new multicarrier technique FMT is characteristic of the significantly lower spectral overlapping between adjacent subchannels. FMT overcomes the weakness of being sensitive to frequency offset in OFDM, but the using of filter banks bring ISI to the system. For this reason, equalizer is necessary in FMT system to eliminate the interference from filter banks.In this thesis, after introducing the basic theory and structure of OFDM and FMT, we compare these two different multicarrier techniques with the way separating subchannels, structure of the system, complexity, efficiency of frequency and performance to interfere, including ISI and ICI. Several key parts in FMT system are discussed, such as the design of filter banks and equalizers. By setting up a simulation platform of FMT system, we get the performance in wireless different environments with frequency offset or multipath interference. The results of simulation indicate that FMT show better performance than OFDM through decaying channels with frequency offset; FMT is a feasible wireless solution in indoor environments or with shortdistance propagation.The independency of decay in different subchannels makes it possible that taking different modulation schemes, loading different transmission power and bits in subchannels according to the real character of them. This loading scheme is called adaptive modulation technique. In chapter 5, many adaptive loading algorithms are discussed, which has been proposed to take into application before. Based on equal power adaptive bit loading algorithm, we put forward an easy, efficient algorithm, called SDR-based adaptive bit loading algorithm. Results of simulation indicate that this algorithm enhances the resistance ability to decay of FMT system, and keeps data rate highly and reliability.We discussed some key issues in this thesis, and only a part of simulation results are showed. Some issues in the FMT system are not discussed, such as time and frequency synchronization, channel estimation and channel coding, which will be researched in the following work.