On Spectrally Precoded OFDM, OFDMA and Constant-envelope OFDM
Date Issued
2011
Date
2011
Author(s)
Chen, Hao-Ming
Abstract
In this thesis, further results of spectrally precoded orthogonal frequency-division signals (SP-OFDM) are investigated. The main contributions of this thesis are described in the following.
In Chap 3, SP-OFDM signals with arbitrary input data statistics are investigated. First, we show that all constraints and spectral precoders previously developed for SP-OFDM with independent and identically distributed and zero-mean data provide fast decaying spectral sidelobes for SP-OFDM with arbitrary input statistics. Next, a general constraint on spectral precoding is developed for SP-OFDM with cyclic prefix (SP-CP-OFDM), unconstrained guard ratios and arbitrary input data statistics to ensure very small power spectral sidelobes decaying asymptotically as f^{-2J-2}, with J a predesigned integer-valued parameter. Some spectral codes are proposed to meet this constraint. It is shown that the proposed SP-CP-OFDM signals can provide higher spectral compactness than previously designed SP-CP-OFDM with block partitioning.
Adaptive SP-CP-OFDM (ASP-CP-OFDM) is studied in Chapter 4. The proposed spectral precoder in Chapter 3 for SP-CP-OFDM is applied to ASP-CP-OFDM on the fading channel. By jointly adapting the precoding order for spectral precoder and the component modulation, the proposed ASP-CP-OFDM is shown to outperform adaptive nonprecoded OFDM and previously designed ASP-CP-OFDM significantly in average spectral efficiency.
In Chapter 5, SP-OFDM with multiple access and CP (SP-CP-OFDMA) is investigated. Specifically, a general constraint on spectral precoding is developed for proposed SP-CP-OFDMA signal formats with unconstrained guard ratios, arbitrary subcarrier allocation and input data statistics to ensure small power spectral sidelobes decaying asymptotically as f^{-2J-2}. A general procedure is proposed to facilitate the precoder design for SP-CP-OFDMA signals with arbitrary subcarrier allocation for each user and some spectral precoders are accordingly devised. It is shown that the proposed SP-CP-OFDMA signals can suppress sidelobe powers effectively and thus achieve higher spectral compactness than nonprecoded rectangularly-pulsed CP-OFDMA.
In Chapter 6, a new spectral precoding scheme is developed for constant-envelope OFDM (CE-OFDM). Specifically, a precoding constraint is developed for the spectrally precoded CE-OFDM (SP-CE-OFDM) signal format with unconstrained guard ratios and arbitrary input data statistics to ensure small power spectral sidelobes decaying asymptotically as f^{-2J-2}. The proposed spectral codes for proposed SP-CP-OFDM signals in Chapter 3 are shown to meet the constraint and thus suited for SP-CE-OFDM. It is shown that the proposed SP-CE-OFDM signal format can provide much smaller spectral sidelobes than the previously designed SP-CE-OFDM block signals.
Subjects
Orthogonal frequency-division multiplexing
multiple access
spectral precoding
asymptotic spectral behavior
cyclic prefix
guard ratio
sidelobe suppression
adaptive modulation
average spectral efficiency
constant-envelope
Type
thesis
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