Experimental evaluation of universal time-domain windowed OFDM-based LTE downlink system by real-time wave-shaping

The 5G system requires flexible and ultrahigh-efficient spectrum usage, while spectrum efficiency is limited by using the conventional LTE and LTE-Advanced based on cyclic prefix-based orthogonal frequency division multiplexing (CP-OFDM) due to the high out-of-band emission (OOBE). Therefore, new-waveforms for reducing the OOBE are required to improve spectrum efficiency and the authors have proposed universal time-domain windowed OFDM (UTW-OFDM) as one of the new-waveforms for the 5G system. The UTW-OFDM has many advantages such as low-OOBE, low-complexity and high-compatibility with conventional CP-OFDM-based systems. In this paper, we developed a UTW converter enabling a proposed UTW-OFDM-based LTE-downlink (DL) system in real time. By applying the UTW converter to the off-the-shelf LTE-DL system, feasibility of the proposed UTW-OFDM is experimentally evaluated. The experimental results show that the UTW-OFDM suppresses power spectrum density at the channel-edge by about 20 dB and 18 dB for QPSK and 64QAM, respectively, without any throughput deterioration compared to the conventional CP-OFDM-based LTE-DL signal.