Communication Systems
Asymptotic spectral behavior of spectrally precoded OFDM signal with arbitrary input statistics
IEEE Communications Letters
An active-set approach for OFDM PAR reduction via tone reservation
IEEE Transactions on Signal Processing
IEEE Transactions on Wireless Communications
Peak-to-mean power control in OFDM, Golay complementary sequences, and Reed-Muller codes
IEEE Transactions on Information Theory
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Spectrally precoded orthogonal frequency-division multiplexing (OFDM) and constant-envelope OFDM (CE-OFDM) are two modified OFDM formats that enhance the signaling features of OFDM, while allowing for the efficient implementation by discrete Fourier transform and the insertion of guard intervals to counteract channel dispersion. The spectrally precoded OFDM signal provides very small power spectral sidelobes decaying asymptotically as f-2J-2, with J an integer-valued design parameter, thereby suppressing sidelobe powers effectively and achieving higher spectral efficiency than nonprecoded rectangularly-pulsed OFDM which has power spectral sidelobes decaying asymptotically as f-2. The CE-OFDM signal exhibits a unity peak-to-average power ratio, and thus enables the efficient use of transmitter's power amplifier. In this paper, a specific CE-OFDM block signaling format is proposed to incorporate spectral precoding with an aim to suppressing sidelobe powers more effectively than conventional nonprecoded CE-OFDM. The general constraint on spectral precoding is developed to ensure that the power spectral sidelobes of the spectrally precoded CE-OFDM block signal with arbitrary data statistics decay asymptotically as f-2J-2. Some spectral codes previously found for spectrally precoded OFDM are shown to meet the constraint and thus suited for spectrally precoded CE-OFDM. Specifically, spectral performance is analyzed for the spectrally precoded CE-OFDM block signal with independent and identically distributed data to illustrate the prevailing spectral advantage. The corresponding receiver is also developed to demodulate the spectrally precoded CE-OFDM block signal over dispersive channels.