Enhanced Universal Filtered-DFTs-OFDM for Long-Delay Multipath Environment

Yuji MIZUTANI  Hiroto KURIKI  Yosuke KODAMA  Keiichi MIZUTANI  Takeshi MATSUMURA  Hiroshi HARADA  

IEICE TRANSACTIONS on Communications      No.4    pp.467-475
Publication Date: 2020/04/01
Publicized: 2019/10/08
Online ISSN: 1745-1345
DOI: 10.1587/transcom.2019EBP3044
Type of Manuscript: PAPER
Category: Wireless Communication Technologies
CP-DFTs-OFDM,  UF-DFTs-OFDM,  long-delay multipath fading environment,  LTE,  beyond 5G,  

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The conventional universal filtered-DFT-spread-OFDM (UF-DFTs-OFDM) can drastically improve the out-of-band emission (OOBE) caused by the discontinuity between symbols in the conventional cyclic prefix-based DFTs-OFDM (CP-DFTs-OFDM). However, the UF-DFTs-OFDM degrades the communication quality in a long-delay multipath fading environment due to the frequency-domain ripple derived from the long transition time of the low pass filter (LPF) corresponding to the guard interval (GI). In this paper, we propose an enhanced UF-DFTs-OFDM (eUF-DFTs-OFDM) that achieves significantly low OOBE and high communication quality even in a long-delay multipath fading environment. The eUF-DFTs-OFDM applies an LPF with quite short length in combination with the zero padding (ZP) or the CP process. Then, the characteristics of the OOBE, peak-to-average power ratio (PAPR), and block error rate (BLER) are evaluated by computer simulation with the LTE uplink parameters. The result confirms that the eUF-DFTs-OFDM can improve the OOBE by 22.5dB at the channel-edge compared to the CP-DFTs-OFDM, and also improve the ES/N0 to achieve BLER =10-3 by about 2.5dB for QPSK and 16QAM compared to the UF-DFTs-OFDM. For 64QAM, the proposed eUF-DFTs-ODFDM can eliminate the error floor of the UF-DFTs-OFDM. These results indicate that the proposed eUF-DFTs-OFDM can significantly reduce the OOBE while maintaining the same level of communication quality as the CP-DFTs-OFDM even in long-delay multipath environment.