Window Processing of SSB CP-OFDM System for the OOB Spectrum Reduction

In order to provide the very fast eMBB (enhanced mobile broadband) service of the next generation mobile communication, it is important to increase the spectrum efficiency for accommodating the more channel capacity. To do this goal, it should have higher frequency efficiency than the existing mobile communication system. Numerous studies have been conducted and are still underway. In this paper, SSB (Single Side Band) modulation is applied into the existing CP (Cyclic Prefix)-OFDM (Orthogonal Frequency Division Multiplexing) as a modulation method to achieve higher frequency efficiency. Conventional SSB modulation is a method that can increase the frequency efficiency twice, because it transmits and receives using half spectrum using analog modulation method. However, it has a disadvantage that it is not easy to perform high-speed transmission compared with digital communication such as CP-OFDM. In this paper, we propose the SSB modulation with the CP-OFDM and sends different information signals to each of the two half spectrum. In addition, to reduce the OOB (Out of Band) power spectrum, the windowing technique is studied using various window functions with many different window lengths. As the simulation results show, As a result, we have confirmed that the BER performance of SSB-CP-OFDM and the spectral OOB power reduction by each window function and length. OOB power reduction of 63 dB can be found when the window length of 32 with the Kaiser window is used. Of course, the longer window length, the lower OOB power spectrum. However, it will be harmonized considering other design parameters.