Peak Reduction Tone Set Research Articles

A novel differential evolution algorithm for tone reservation based peak to average power ratio reduction technique in orthogonal frequency division multiplexing systems

A critical problem in the Orthogonal Frequency Division Multiplexing (OFDM) framework for 5G communication is the high Peak to Average Power Ratio (PAPR) of the transmitted signal. The Tone Reservation (TR) scheme is employed to minimize the OFDM signal’s PAPR in time domain. It is comprised of some reserved subcarriers to generate a Peak Reduction Tone (PRT) set. The selection of these PRT set and the optimal target clipping level are the depending parameters of the PAPR reduction performance. A novel Differential Evolution based Tone Reservation (DE-TR) scheme is proposed to find an optimal PRT set and then the PAPR is reduced by employing an Optimized Iterative Clipping and Filtering (OICF) technique. Compared to other related techniques like Clipping Control Tone Reservation (CC-TR), Curve Fitting based Tone Reservation (CF-TR) and Parallel Tabu Search Tone Reservation (PTS-TR), the proposed technique DE-TR(Pro.) contributes to a substantial PAPR reduction output with lower computational complexity and maintaining an adequate bit error rate (BER) and spectral spreading efficiency. In addition, the theoretical relationship between the Error Vector Magnitude (EVM) and PAPR as well as CCDF performance with EVM are analyzed.

PAPR Reduction Based on Parallel Tabu Search for Tone Reservation in OFDM Systems

In this letter, we focus on the high peak to average power ratio (PAPR) reduction problem in tone reservation-based orthogonal frequency division multiplexing systems. We first propose a parallel Tabu search (PTS)-based scheme to find a sub-optimal peak reduction tone (PRT) set. After finding the sub-optimal PRT set, we apply it in an adaptive iterative clipping and filtering (AICF) method for PAPR reduction. Furthermore, PAPR reduction and bit error rate (BER) performances are compared among the AICF method, the adaptive scaling, the adaptive amplitude clipping and the fast iterative shrinkage-thresholding algorithm schemes. Simulation results verify that the PTS-based PRT scheme can obtain better secondary peaks with lower computational complexity, and the AICF scheme effectively reduces PAPR with a faster convergence speed while its BER performance is only slightly worse than for the existing methods.

Peak‐to‐average power ratio reduction of orthogonal frequency division multiplexing systems using modified tone reservation techniques

SummaryThis paper proposed a modified tone reservation (TR) technique that can reduce the peak‐to‐average power ratio (PAPR) of the orthogonal frequency division multiplexing (OFDM) system and is able to correct errors to avoid channel interference. The TR technique is a widely used PAPR reduction technique, which divides subcarriers of the OFDM system into two sets to generate peak‐canceling signals and transmit modulated data. The subcarriers used to reduce the PAPR are called the peak reduction tone sets. The mechanism of peak‐canceling signal generation is a primary factor in determining the quality of the PAPR reduction performance of the TR technique. Currently, two signal generation mechanisms exist: TR‐gradient‐based and TR‐clipping‐based techniques. Although TR techniques can effectively reduce the high PAPR in the OFDM system, TR techniques lack the ability to correct errors. Therefore, this paper combined block coded modulation codes and TR techniques to provide the modified TR techniques with error correction abilities. From the simulation results, the modified TR techniques had a superior effect on PAPR reduction performance compared with the conventional TR technique. The modified TR technique also possessed the ability to correct errors during signal transmission. Copyright © 2015 John Wiley & Sons, Ltd.

PAPR reduction of OFDM using invasive weed optimization-based optimal peak reduction tone set selection

Abstract Tone reservation (TR) is one of the attractive techniques to reduce peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing system. As conventional TR technique requires exhaustive searching over all the combinations of the given peak reduction tone (PRT) sets, it results in computational complexity that increases exponentially with the number of the subcarriers. In this paper, we aim to obtain a desirable PAPR reduction with low computational complexity. Since the process of searching the optimal PRT set can be categorized as combinatorial optimization with some variables and constraints, we propose a novel scheme, which is based on a nonlinear optimization approach named as invasive weed optimization method, to search the optimal combination of PRT set with low complexity. To validate the analytical results, extensive simulations have been conducted, showing that the proposed schemes can achieve significant reduction in computational complexity while keeping good PAPR reduction. As results of simulations, the proposed scheme shows almost the same PAPR reduction performance as compared with the genetic algorithm-based TR method which has been known to have the best performance and obtains near-optimal PRT sets.

A Nearly Optimal Peak Reduction Tone Set Selection Algorithm

In tone reservation-based OFDM systems, the peak to average power ratio (PAPR) reduction performance mainly depends on the selection of peak reduction tone (PRT) set. it is known that finding the optimal PRT set requires an exhaustive search of all combination of possible PRT sets, and this search is infeasible for the number of tones used in practical systems. The existing selection methods perform poorly or incur high computational complexity. In this paper, an efficient scheme based on particle swarm optimization algorithm (PSO) is proposed to search the nearly optimal PRT set.Simulation results show that our proposed algorithm can obtain a nearly optimal PRT set and good PAPR reductions.

Genetic Algorithm Based Nearly Optimal Peak Reduction Tone Set Selection for Adaptive Amplitude Clipping PAPR Reduction

In tone reservation (TR) based OFDM systems, the peak to average power ratio (PAPR) reduction performance mainly depends on the selection of the peak reduction tone (PRT) set and the optimal target clipping level. Finding the optimal PRT set requires an exhaustive search of all combinations of possible PRT sets, which is a nondeterministic polynomial-time (NP-hard) problem, and this search is infeasible for the number of tones used in practical systems. The existing selection methods, such as the consecutive PRT set, equally spaced PRT set and random PRT set, perform poorly compared to the optimal PRT set or incur high computational complexity. In this paper, an efficient scheme based on genetic algorithm (GA) with lower computational complexity is proposed for searching a nearly optimal PRT set. While TR-based clipping is simple and attractive for practical implementation, determining the optimal target clipping level is difficult. To overcome this problem, we propose an adaptive clipping control algorithm. Simulation results show that our proposed algorithms efficiently obtain a nearly optimal PRT set and good PAPR reductions.

Tone Reservation Using Near-Optimal Peak Reduction Tone Set Selection Algorithm for PAPR Reduction in OFDM Systems

This letter considers selection of the optimal peak reduction tone (PRT) set for the tone reservation (TR) scheme to reduce the peak-to-average power ratio (PAPR) of an orthogonal frequency division multiplexing (OFDM) signal. In the TR scheme, PAPR reduction performance achieved by a randomly generated PRT set is superior to that by a consecutive PRT set and that achieved by an interleaved tone set. However, the optimal PRT set requires an exhaustive search of all combinations of possible PRT sets, which is known to be a nondeterministic polynomial-time (NP)-hard and cannot be solved for the practical number of tones. Inspired by the efficiency of the cross-entropy (CE) method for finding near-optimal solutions in huge search spaces, this letter proposes the application of the CE method to search the optimal PRT set. Computer simulation results show that the proposed CE method obtains near-optimal PRT sets and provides better PAPR performance.

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.

Near Optimal PRT Set Selection Algorithm for Tone Reservation in OFDM Systems

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> In the tone reservation (TR) scheme, it is known that finding the optimal peak reduction tone (PRT) set is equivalent to solving the secondary peak minimization problem. However, this problem cannot be solved for the practical number of tones because it is nondeterministic polynomial-time (NP)-hard. In this paper, two efficient methods for selecting a near optimal PRT set are proposed. The first method is a random search algorithm with reduced computational complexity based on the observation that the secondary peak value of the time domain kernel, which is obtained by inverse fast Fourier transforming the characteristic sequence of the PRT set, statistically tends to decrease as the variance of the time domain kernel decreases. The second method is a deterministic selection algorithm using the cyclic difference set. The near optimality of these methods is confirmed through the numerical analysis. </para>