Design and Performance Evaluation of SW(Single extension Windowing)-Based CP-OFDM System for the Sharp OOB Spectrum

Abstract

In 5th Generation (5G), the Orthogonal Frequency Division Multiplexing (OFDM) system is adopted as a core modulation technique. OFDM has a problem of high Out-Of-Band (OOB) power which reduces spectral efficiency in frequency allocation problem. A lot of research is going on to solve this OOB power problem. For example, there are Filter Bank Multi-Carrier (FBMC), Universal Filtered Multi-Carrier (UFMC) and Weighted Overlap and add based (WOLA)-OFDM. In this paper, we use windowing method to reduce OOB power. However, if windowing is applied as it is, the part without CP is damaged. Therefore, we propose a Single extension Windowing (SW) system that performs windowing after a single extension is applied to the damaged part. In addition, we propose gradual waveform on data part for more OOB power reduction. We confirm trade-off between Bit Error Rate (BER) performance degradation and OOB power reduction. Simulation results show that the BER performance degradation caused by windowing can be overcome using SW system. The OOB power reduction effect through gradual waveform confirmed that there is a 3dB BER performance degradation when OOB power reduction of up to 8dB is obtained. In this paper, we compared OOB power between CP-OFDM with windowing and CP-OFDM with conventional CP-OFDM and evaluate the performance difference.