Hyun-Bae Jeon

A Low-Complexity SLM Scheme Using Additive Mapping Sequences for PAPR Reduction of OFDM Signals

The selected mapping (SLM) scheme is one of the well-known peak-to-average power ratio (PAPR) reduction schemes for orthogonal frequency division multiplexing (OFDM) systems. A number of low-complexity SLM schemes have been proposed but most of them reduce the computational complexity at the cost of bit error rate (BER) or PAPR reduction performance degradation. In this paper, a new low-complexity SLM scheme is proposed, which generates alternative signal sequences by adding mapping signal sequences to an OFDM signal sequence. The proposed scheme considerably reduces the computational complexity without sacrificing BER and PAPR reduction performance only by requiring additional memory to save the additive mapping signal sequences, especially for the OFDM system with quadrature amplitude modulation (QAM). Similarly, a low-complexity SLM scheme is proposed for multi-input multi-output (MIMO) OFDM system with space-frequency block code (SFBC).

Multi-Stage TR Scheme for PAPR Reduction in OFDM Signals

In the tone reservation (TR) scheme of the orthogonal frequency division multiplexing (OFDM) systems, there exists a trade-off between the peak to average power ratio (PAPR) reduction performance and the peak reduction tone (PRT) set size. In this paper, we propose a multi-stage TR scheme for PAPR reduction, which adaptively selects one of several PRT sets according to the PAPR of OFDM signal while the PRT set is fixed for the conventional TR scheme. It is shown that the PAPR reduction performance of the proposed scheme is better than that of the conventional TR scheme when the tone reservation rate (TRR) is the same.

A New Blind SLM Scheme With Low Decoding Complexity for OFDM Systems

In this paper, a new blind selected mapping (BSLM) scheme is proposed for orthogonal frequency division multiplexing systems. The proposed BSLM scheme embeds the side information identifying a phase sequence into itself by giving the optimal phase offset to the elements of each phase sequence, which are determined by the biorthogonal vectors for the partitioned subblocks. When U phase sequences and maximum likelihood decoder are used, the proposed BSLM scheme reduces the decoding complexity by (U-2)/U compared with the conventional BSLM scheme. Also, pairwise error probability (PEP) analysis for the proposed BSLM scheme is performed over the fading channel. Based on the PEP analysis, the bit error rate (BER) performance of the proposed BSLM scheme is shown to be determined by the subblock partitioning and phase offset. Finally, it is shown that for QPSK and 16-QAM, the detection failure probability and the BER of the proposed BSLM scheme are almost the same as those of the conventional BSLM scheme through numerical analysis.

A New PAPR Reduction Scheme Using Efficient Peak Cancellation for OFDM Systems

A new computationally efficient peak-to-average power ratio (PAPR) reduction scheme for orthogonal frequency division multiplexing (OFDM) signals is proposed, which utilizes the parabolic peak cancellation (PPC) using the truncated kernel signal generated from the inverse fast Fourier transform (IFFT) of the shaped peak reduction tones (PRTs). The proposed scheme only repeats peak canceling in the time domain without iteratively performing IFFT and FFT. Also, the application of the proposed PPC scheme to active constellation extension (ACE) can reduce the number of iterations of IFFT and FFT. Moreover, a transmit power allocation scheme is also suggested to relieve the degradation of bit error rate (BER) of the proposed PAPR reduction scheme. Numerical analysis shows that if the shaping parameters of PRTs are chosen properly, out-of-band (OOB) radiation and BER can be improved while the PAPR reduction performance is maintained.

Bit-Based SLM Schemes for PAPR Reduction in QAM Modulated OFDM Signals

In this paper, we propose two bit-based selected mapping (SLM) schemes for reducing peak to average power ratio (PAPR) of orthogonal frequency division multiplexing (OFDM) signals with quadrature amplitude modulation (QAM), called bitwise SLM (BSLM) and partial bit inverted SLM (PBISLM). Contrary to the conventional SLM which rotates the phases of QAM symbols in the frequency domain, the proposed schemes change the magnitudes as well as the phases of QAM symbols by applying binary phase sequences to the binary data sequence before mapped to QAM symbols. Simulation results show that the proposed schemes have better PAPR reduction performance with shaping gain than the conventional SLM scheme for the QAM modulated OFDM signals, especially for the small number of subcarriers.

Low-complexity selected mapping scheme using cyclic-shifted inverse fast Fourier transform for peak-to-average power ratio reduction in orthogonal frequency division multiplexing systems

In this study, a new peak-to-average power ratio (PAPR) reduction scheme for orthogonal frequency division multiplexing (OFDM) is proposed based on the selected mapping (SLM) scheme. The proposed SLM scheme generates alternative OFDM signal sequences by cyclically shifting the connections in each subblock at an intermediate stage of inverse fast Fourier transform (IFFT). Compared with the conventional SLM scheme, the proposed SLM scheme achieves similar PAPR reduction performance with much lower computational complexity and no bit error rate degradation. The performance of the proposed SLM scheme is analysed mathematically and verified through numerical analysis. Also, it is shown that the proposed SLM scheme has the lowest computational complexity among the existing low-complexity SLM schemes exploiting the signals at an intermediate stage of IFFT.

A new selected mapping scheme for PAPR reduction in OFDM systems

In this paper, a new SLM scheme for peak to average power ratio (PAPR) reduction in orthogonal frequency division multiplexing (OFDM) systems is proposed. This scheme is special case of selected mapping (SLM) scheme. The proposed SLM scheme generates alternative OFDM signal sequences by exploiting the intermediate OFDM signal sequence in inverse fast Fourier transform (IFFT). By using this technique, the proposed SLM scheme achieves similar PAPR reduction performance with much lower computational complexity and no bit error rate (BER) degradation. the performance of the proposed SLM scheme is verified through the simulations.

A New Blind SLM Scheme with Low Complexity of OFDM Signals

In this paper, we propose a new blind SLM scheme with low complexity using m-sequence as a phase sequence in OFDM. The proposed scheme significantly reduces the compu- tational complexity for searching the side information of the phase sequence and decoding the alternative symbol sequence at the receiver. After generating alternative symbol sequences using a set of phase sequences, the side information for each alternative symbol sequence is embedded in it through block partitioning and phase rotation. The proposed method does not need additional inverse fast Fourier transform (IFFT) and has the same PAPR reduction performance compared to the conventional SLM scheme. In order to find the side information, a maximum likelihood (ML) decoder with lower complexity is derived, which guarantees lower detection failure probability of side information compared to the conventional blind SLM scheme.

New SLM scheme for PAPR reduction in OFDM signals

In this paper, we propose a new selected mapping (SLM) scheme for reducing peak to average power ratio (PAPR) of orthogonal frequency division multiplexing (OFDM) signals, called bit SLM scheme. In the conventional SLM, the alternative symbol sequences are generated by rotating the phases of the M-ary symbols in the frequency domain. However, in the proposed scheme, the alternative symbol sequences are generated by multiplying the data in the binary expression by the binary phase sequences before mapping to quadrature amplitude modulation (QAM) symbols. Simulation results show that the bit SLM scheme has better PAPR reduction performance compared to the conventional SLM scheme, especially for the QAM modulated OFDM signal for the small size of inverse fast Fourier transform (IFFT).

Peak to average power ratio reduction for OFDM systems with low complexity

Orthogonal frequency division multiplexing (OFDM) has gained popularity as a standard for various high data rate wireless communication systems due to the spectral bandwidth efficiency, robustness to frequency selective fading channels, etc. However, its high peak-to-average power ratio (PAPR) causes significant in-band distortion and high out-of-band radiation when it passes through a nonlinear device such as a high power amplifier (HPA). This paper reviews the main PAPR reduction schemes and introduces their modifications for achieving low-complexity required for practical implementation in wireless communication systems.