Widely-Linear Nyquist Criteria for DFT-Spread OFDM of Constellation-Rotated PAM Symbols
SCIE
SCOPUS
- Title
- Widely-Linear Nyquist Criteria for DFT-Spread OFDM of Constellation-Rotated PAM Symbols
- Authors
- CHOI, JEONG HOON; KIM, JU BUM; CHO, JOON HO; Lehnert, James S.
- Date Issued
- 2021-05
- Publisher
- Institute of Electrical and Electronics Engineers
- Abstract
- In this paper, the Nyquist criteria for ordinary linear modulation are generalized to the discrete-Fourier transform-spread (DFT-spread) orthogonal frequency-division multiplexing (OFDM) of constellation-rotated PAM symbols. Unlike the conventional Nyquist criteria with a linear receiver, the new criteria are to remove intersymbol interference in the output of a widely-linear (WL) receiver. It is shown that not only the folded spectrum, but also the shifted and reverse-folded spectrum is crucial in the criteria, where the shift offset is determined by the rotation angle. As a design example, combinations of a constellation rotation angle and a square-root raised cosine pulse are proposed. It is shown that the proposed design can achieve better performance both in spectral efficiency and in peak-to-average power ratio than the conventional DFT-spread OFDM of pi/2-BPSK symbols. The optimal one-tap frequency-domain equalizer is also derived under the WL zero-forcing (ZF) constraint. It is shown that, when the rotation angle is properly chosen, the proposed one-tap WL-ZF equalizer significantly outperforms the one-tap linear ZF equalizer in output signal-to-noise ratio. The proposed equalizer also outperforms the conventional equalizer in error vector magnitude measured at the output of a nonlinear power amplifier.
- URI
- https://oasis.postech.ac.kr/handle/2014.oak/106847
- DOI
- 10.1109/TCOMM.2021.3056106
- ISSN
- 0090-6778
- Article Type
- Article
- Citation
- IEEE Transactions on Communications, vol. 69, no. 5, page. 2909 - 2922, 2021-05
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