PAPR Reduction Performance Research Articles

Simplified Approach to Optimized Iterative Clipping and Filtering for PAPR Reduction of OFDM Signals

Iterative clipping and filtering (ICF) is a well-known technique to reduce the peak-to-average power ratio (PAPR) of orthogonal frequency division multiplexing (OFDM) signals. Recently, Wang and Luo investigated the clipped signal and proposed a modified algorithm called optimized ICF (OICF). This is an optimal algorithm since it can achieve the required PAPR reduction with minimum in-band distortion and far fewer iterations. However, OICF needs to solve a convex optimization problem with O(N3) complexity, where N represents the number of subcarriers. In this paper, instead of analyzing the clipped signal, we study the clipping noise and propose a simplified OICF algorithm. In the new algorithm, solving the convex optimization problem is approximated by some simple algebraic operations and the computational complexity reduces to O(N). Simulation results show that after three iterations, the original OICF algorithm can achieve the desired PAPR while the simplified one exhibits almost the same performance: for a 128-subcarrier and quadrature phase shift keying (QPSK) modulated OFDM system, the PAPR-reduction performance difference between the two algorithms are 5×10-3dB at a 10-4 clipping probability and the bit-error-rate performance difference is 6×10-3 dB at a 10-7 error probability.

A Novel Multi-Points Square Mapping Combined With PTS to Reduce PAPR of OFDM Signals Without Side Information

In this paper, we first propose a novel multi-points square mapping (MSM) scheme. Then, we describe in detail how to combine the proposed MSM scheme with conventional partial transmit sequence (C-PTS) scheme, named as M-PTS, to reduce the PAPR of OFDM signals. Compared with C-PTS, the proposed M-PTS scheme needs not to submit side information while keeping almost the same performance of PAPR reduction as the C-PTS scheme. Extensive simulations are conducted to validate analytical results, showing that the proposed M-PTS scheme has better bandwidth efficiency and bit error ratio (BER) performance compared with the C-PTS scheme.

A Partitioned-SLM with Low Complexity for OFDM PAPR Reduction

We propose the P-SLM (Partitioned-Selected Mapping) scheme with low complexity for PAPR reduction of OFDM signals. In the proposed scheme, a symbol sequence in the frequency domain is partitioned into several sub-blocks which are multiplied by different orthogonal phase sequences whose length and number are shorter and smaller than those used in the conventional SLM. Then, among various sequences in the time domain generated after the IFFT for the SLM sub-blocks, the sub-block combination with the lowest PAPR is selected and transmitted. Simulation results show that the proposed P-SLM scheme significantly reduces the number of IFFT calculation and multiplication than the conventional SLM without loss of PAPR reduction performance.

PTS with Non-Uniform Phase Factors for PAPR Reduction in OFDM Systems

Partial transmit sequence (PTS) is one of the effective and uncomplicated PAPR reduction methods for OFDM systems. The phase factors applied in the weighting sequences are assumed to be uniformly distributed within [0, 2pi). By carefully investigating the phase distribution of OFDM signals, we proposed a modified PTS scheme outperforming the conventional PTS scheme in PAPR reduction performance. The process of the proposed scheme is the same as the conventional PTS, except for applying the new non-uniform phase factors. The required side information is the same as the conventional PTS applying uniform phase factors.

An Adaptive SLM Scheme Based on Peak Observation for PAPR Reduction of OFDM Signals

We propose an adaptive SLM scheme based on peak observation for PAPR reduction of OFDM signals. The proposed scheme is composed of three steps: peak scaling, sequence selection, and SLM procedures. In the first step, the peak signal samples in the IFFT outputs of the original input sequence are scaled down. In the second step, the sub-carrier positions where the power difference between the original input sequence and the FFT output of the scaled signal is large, are identified. Then, the phase sequences having the maximum number of phase-reversed sequence words only for these positions are selected. Finally, the generic SLM procedure is performed by using only the selected phase sequences for the original input sequence. Simulation results show that the proposed scheme significantly reduce the complexity in terms of IFFT and PAPR calculation than the conventional SLM, while maintaining the PAPR reduction performance.

A New Peak-to-Average Power-Ratio Reduction Algorithm for OFDM Systems via Constellation Extension

Peak-to-average power-ratio (PAPR) reduction for OFDM systems is investigated in a probabilistic framework. A new constellation extension technique is developed whereby the data for each subcarrier are represented either by points in the original constellation or by extended points. An optimal representation of the OFDM signal is achieved by using a de-randomization algorithm where the conditional probability involved is handled by using the Chernoff bound and the evaluation of the many hyperbolic cosine functions involved is replaced by a tight upper bound for these functions. The proposed algorithm can be used by itself or be combined with a selective rotation technique described in the paper and with other known algorithms such as the coordinate descent optimization and selective mapping algorithms to achieve further performance enhancements at the cost of a slight increase in the computational complexity. When compared with other existing PAPR-reduction algorithms, the enhanced algorithm offers improved PAPR-reduction performance and improved computational complexity although, the transmit power is increased somewhat