Spectrally Precoded DFT-Based OFDM and OFDMA With Oversampling

• Published in: IEEE transactions on vehicular technology Vol. 63; no. 6; pp. 2769 - 2783
• Main Authors: Wu, Tsung-Wei, Chung, Char-Dir
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.07.2014; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Algorithms; Applied sciences; Approximation; Asymptotic properties; Circuit properties; Decay; Discrete Fourier transform; Discrete Fourier transforms; Electric, optical and optoelectronic circuits; Electronic circuits; Electronics; Exact sciences and technology; Fourier transforms; Frequency-domain analysis; Indexes; Information, signal and communications theory; Mathematical analysis; Multiplexing; Orthogonal Frequency Division Multiplexing; orthogonal frequencydivision multiple access; Oversampling; Passband; Peak to average power ratio; Signal and communications theory; Signal convertors; Spectra; spectral precoding; Switching and signalling; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Transmission and modulation (techniques and equipments); Vectors; Waveforms; Discrete Fourier transform (DFT); orthogonal frequency-division multiple access (OFDMA); spectral precoding; orthogonal frequency-division multiplexing (OFDM); oversampling; Performance evaluation; Waveform; Lateral lobe; Multiple access; Design criterion; Coding circuit; Spectral properties; Multicarrier; Peak to average power ratio; Discrete Fourier transformation; Frequency division multiple access; Compact design; Oversampling; Signalling; Coding; Diagonal matrix; Orthogonal frequency division multiplexing; Pretreatment; Power spectrum
• ISSN: 0018-9545; 1939-9359
• DOI: 10.1109/TVT.2013.2292877

Spectrally precoded orthogonal frequency-division multiplexing (SP-OFDM) and SP-OFDM multiple access (SP-OFDMA) are bandwidth-efficient rectangularly pulsed multicarrier signaling formats that can provide power spectral sidelobes decaying asymptotically as f -2L-2 , with L being a preassigned positive-integer design parameter, which results in a compact spectrum. The existing spectral precoders for SP-OFDM and SP-OFDMA are designed based on the rectangularly pulsed analog multicarrier waveform representation that has an unlimited power spectrum; thus, the corresponding waveforms cannot be exactly synthesized in a discrete Fourier transform (DFT) structure. Consequently, these spectral precoders are subject to modification in DFT-based OFDMA and OFDM systems in which signaling waveforms are digitally synthesized with the use of DFT and provide discrete approximation embodiments to analog multicarrier waveform counterparts. In this paper, a general constraint on spectral precoding and the corresponding spectral precoders are developed for DFT-based OFDMA and OFDM with oversampling to ensure the desirable spectral property that the resultant spectrally precoded DFT-based waveforms provide powerspectral-sidelobe envelope bounds decaying asymptotically as f -2L-2 . It is analytically shown that the precoders suitable to DFT-based waveforms can be simply obtained by properly transforming the previously designed precoders suitable to corresponding analog multicarrier waveforms with an appropriate diagonal phase-rotation matrix, while yielding similar spectral performance and peak-to-average power ratio (PAPR) characteristics.