Trade-Off Characteristic between BER Performance and OOB Power Emission in WR-OFDM System

By applying the windowing process, the sharper OOB spectral characteristics can be obtained, which can be used for the reduction of guard band between the operators frequency assignment and can save the very valuable frequency resources. WR-OFDM (window and reconstruction – orthogonal frequency division multiplex) system is proposed to upgrade the existing CP-OFDM system for research of mobile communication system after 5th generation. We have applied window function and analyzed performance change according to window length. This system can improve efficiency of spectrum resources by reducing gap from adjacent channels. The WR-OFDM system complements disadvantage that OOB (out-of-band power of the existing CP-OFDM system is high. In transmitter, the window function is applied to lower OOB power and receiver reconstructs damaged data through restructuring process. In this way, OOB power can be reduced without additional time resources such as time extension. However, in WR-OFDM system, partial interference occurs by applying the window function and multipath delay signal in multipath channel. In this study, we investigated effect of window length on BER performance in WR-OFDM system and obtained the interaction formula between window length and multipath delay signal through simulation with each tap of multipath delay signal. Also, it can be confirmed that adjusting the window length in the multipath channel can mitigate trade-off characteristics between OOB power reduction and BER performance.