Optimal Filter Length Selection for Universal Filtered Multicarrier Systems

Future wireless networks will use Universal Filtered Multicarrier (UFMC) as a new waveform modulation technique. The UFMC waveform sensibly considers the sub-band filter specifications such as filter order, and shape to combine the key benefits of the present generation modulation waveforms while averting their disadvantages. Therefore, in UFMC-based systems, it is important to pay attention to how the sub-band filter is made. In this paper, the sub-band filter configuration is adapted according to the sub-band size such that the UFMC symbol generates the minimum level of interference with minimum frequency selectivity. Also, the total interference caused by inter-carrier interference (ICI) and inter-sub-band interference (ISBI) was studied by finding the closed form of its change in the UFMC signal with sub-band size and filter length. From this analysis, we determined the ICI increases and ISBI decreases with filter length.  Therefore, the proposed method optimizes the filter length in terms of sub-band size and interference. By this approach, the filter length is shorter than the conventional method and hence improves the symbol utilization. With the proposed method, the overall signal-to-interference ratio (SIR) improved by 1 to 3 dB.