Implementation Of Filtered Multi Tone System Based On Fast Convolution

In order to meet the explosive growth of massive mobile data traffic, the fifth generation mobile communication network(5G) requires maximization utilization of the various types of spectrum resources. This demands the transmission waveform of the physical layer with high spectral resolution and high spectral density. Filtered MultiTone(FMT) is one of multicarrier modulation technique based on filter banks. Compared with Orthogonal Frequency Division Multiplexing(OFDM), known as the key physical technology of 4G, FMT can flexibly select the optimized filter banks instead of rectangular window function to achieve higher spectral resolution and better spectral containment, thus avoiding the overhead of cyclic prefix and virtual carriers. However, the FMT is more complicated to be implemented than OFDM due to its longer requirement for prototype function than symbol period to meet frequency containment. Meanwhile, the existing implementation method of FMT also has shortage in flexibility, restricting its further application in future network.Aiming at these problems, this thesis has carried on detailed research to the FMT system, and the main work is shown as follows:1. The FMT implementation scheme based on fast convolution(FC-FMT) is proposed. Instead of time domain realization, FC-FMT realizes FMT system in frequency domain with the help of frequency sampling based prototype implementation, by using overlap-add fast convolution methods to convert time-domain convolution into frequency-domain product. Then the simulation results of FC-FMT with non-overlapping subcarrier verify the effectiveness of the proposed scheme, and show that the prototype filter and overlap factor are two main factors which affect the performance of FC-FMT.2. Three kinds implementation scheme of FMT are studied, including direct implementation, polyphase implementation and fast convolution implementation. The comparison results show that the spectrum efficiency of FC-FMT is affected by oversampling factor, but FC-FMT has low-speed operating rate and less complexity, making it more suitable for high-speed data transmission. Meanwhile, FC-FMT exhibits higher flexibility and simplicity in adjusting the sub-channel bandwidths and center frequencies, thus it is convenient to turn on/off a chunk of spectrum.3. Spectral-Overlapping is introduced in FC-FMT. Aiming at the low spectral efficiency of FC-FMT, the intentional spectral overlapping with the gradient in the level of frequency bins is introduced to the FC-FMT. Firstly the interference filter is theoretically derived, and the simulation results states that the improvement of spectral efficiency for Overlapping FC-FMT without damaged extra ICI. Secondly the simulation platform of Overlapping FC-FMT is constructed, and the simulation results dictates that different parameter configuration, such as overlap factor, overlap frequency bins and roll-off factor, can achieve various performance, including computation complexity, spectrum efficiency and mean square error, etc. As a consequence, FC-FMT has some superiority to meet varying transport requirements for multi-services only by setting simple parameter.