In this paper, we first propose a novel construction of 16-quadrature amplitude modulation (QAM) near-complementary sequences with low peak-to-mean envelope power ratio (PMEPR) in orthogonal frequency division multiplexing (OFDM) systems. The proposed 16-QAM near-complementary sequences can be constructed by utilizing novel nonlinear offsets, where the length of the sequences is n = 2m. The family size of the newly constructed 16-QAM near-complementary sequences is 8 × (m!/2) × 4m+1, and the PMEPR of these sequences is proven to satisfy PMEPR ≤ 2.4. Thus, the proposed construction can generate a number of 16-QAM near-complementary sequences with low PMEPR, resulting in the improvement of the code rate in OFDM systems. Furthermore, we also propose a novel construction of 64-QAM near-complementary sequences with low PMEPR, which is the first proven construction of 64-QAM near-complementary sequences. The PMEPRs of two types of the proposed 64-QAM near-complementary sequences are proven to satisfy that PMEPR ≤ 3.62 or PMEPR ≤ 2.48, respectively. The family size of the newly constructed 64-QAM near-complementary sequences is 64 × (m!/2) × 4m+1.

Abstract In this paper, we propose a constellation amplitude modification (CAM) method to reduce the peak‐to‐average power ratio (PAPR) in orthogonal frequency division multiplexing systems. The key idea of the proposed CAM method is to modify the original constellation amplitude and choose the constellation points with the minimum PAPR as the transmitted constellation points. The CAM method formulates the PAPR reduction as a convex optimization problem, and then, it applies the customized interior‐point method to solve the optimization problem. Compared with the traditional methods, the CAM method does not increase the transmit power, and the receiver has no additional operations. Simulation results show that the CAM method converges fast and offers significant PAPR reduction. Copyright © 2016 John Wiley & Sons, Ltd.

In this paper, we propose a novel additive cancellation signal (ACS) method for sidelobe suppression in non-contiguous orthogonal frequency division multiplexing (NC-OFDM) based CR systems. The key idea of the proposed method is to dynamically add several additive cancellation symbols on both the primary user (PU) subcarriers and the secondary user (SU) subcarriers, to generate the additive cancellation signals for suppressing the sidelobe power of NC-OFDM signals. Moreover, the ACS method formulates the problem of sidelobe suppression as a quadratically constrained quadratic program (QCQP), and the optimal additive cancellation signal can be obtained by the standard interior-point method. Simulation results show that the proposed ACS method can provide significant sidelobe suppression performance.

In this study, a novel phase offset‐based partial transmit sequence (PTS) scheme is proposed to reduce the peak‐to‐average power ratio (PAPR) in Alamouti coded multi‐input–multi‐output orthogonal frequency division multiplexing systems, and its key idea is that different phase rotation sequences are multiplied by their corresponding phase offsets at the transmitter. Moreover, a minimum Euclidean distance decoder is proposed to recover the phase rotation sequences at the receiver. The theoretical analysis and simulation results show that the proposed PTS scheme could offer good performances of both the bit error rate and the PAPR reduction without transmitting the side information, resulting in the increase of the data rate.

In this letter, a novel phase offset selected mapping (SLM) scheme is proposed to reduce the peak-to-average power ratio (PAPR) in Alamouti coded multi-input multi-output orthogonal frequency division multiplexing (MIMO-OFDM) systems, and its key idea is that different phase rotation sequences are multiplied by their corresponding phase offsets at the transmitter. Moreover, a minimum Euclidian distance (MED) decoder at the receiver is proposed to recover the phase rotation sequences. Therefore, the proposed SLM scheme does not need to reserve bits for the transmission of side information, resulting in the increase of the data rate. Theoretical analysis and simulation results show that the proposed SLM scheme could offer good performances of both the bit error rate and PAPR reduction.