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$N$ -continuous orthogonal frequency division multiplexing (OFDM) is a promising solution to the out-of-band (OOB) emission issue in OFDM systems where the $N$ th-order continuity between OFDM symbols leads to lower OOB emission than the plain OFDM; however, high self-interference in such systems is an obstacle. In this paper, we propose a new class of quasi-cyclic symbol extensions, which makes the OFDM system $N$ -continuous. The new extension leads to low OOB emission while the additive interference is less than other $N$ -continuous OFDM systems. Moreover, we propose a general analysis of the spectrum and interference that occurs in a linear precoded OFDM system. The framework is applicable to many $N$ -continuous OFDM systems including our proposed method. [ABSTRACT FROM AUTHOR]

This paper investigates the application of $N$ -continuous spectral projection precoding design to single-carrier frequency-division multiple access (SC-FDMA). It first considers a general orthogonal projection-based precoded system with an improved iterative receiver and analyzes its ultimate performance in an additive white Gaussian noise channel, both in terms of achievable throughput and symbol-error rates. For $N$ -continuous SC-FDMA, the distribution of the symbol errors is very much asymmetric; a few base pulses carry the lion share of the self-induced interference, resulting in a zero throughput. We show that an optimized transmission and reception scheme based on a polarized use of the base pulses can satisfactorily deal with this asymmetry, and the end-to-end throughput can be recovered to be close to optimal. Applying a similar scheme to $N$ -continuous OFDM enables also an improved performance in the high-SNR regime, where the interference effect strikes the most. [ABSTRACT FROM AUTHOR]

A new precoder structure reduces an OFDM signal's out-of-band emission by tens of decibels while allowing a receiver to employ a classical OFDM channel estimator. [ABSTRACT FROM PUBLISHER]