A novel simplified tone reservation combined with cross antenna rotation and inversion to reduce PAPR for MIMO‐OFDM system

In this paper, we first propose a simplified tone reservation (STR) method with low computational complexity which is based on the Fourier series expansion. Then, we analyze how to combine the STR method with the cross antenna rotation and inversion method to reduce the peak‐to‐average power ratio (PAPR) for multi‐input multi‐output orthogonal frequency division multiplexing (MIMO‐OFDM) system. To validate the analytical results, extensive simulations are conducted and the numerical results show the efficiency of the proposed schemes including the PAPR reduction and low computational complexity for MIMO‐OFDM system. Copyright © 2010 John Wiley & Sons, Ltd.     

A partial transmit sequence technique with error correction capability and low computation

Orthogonal frequency division multiplexing (OFDM) is a popular transmission technique in wireless communication. Although already widely addressed in many studies, OFDM still has flaws, one of which is the occurrence of high peak‐to‐average power ratio (PAPR) in the transmission signal. The partial transmit sequence (PTS) technique is one method adopted to reduce high PAPR in OFDM systems. However, as PTS utilizes phase factors to generate multiple candidate signals, large amounts of calculation and time are required to search the candidate signal with the minimal PAPR, which will then be adopted as the final transmission signal. This paper proposes a novel PAPR reduction method, which can be applied in OFDM systems with M‐ary phase‐shift keying modulation. It not only requires less computation but also possesses error correction capabilities. More precisely, the proposed method is to divide a block‐coded modulation code into the direct sum of a correcting subcode for encoding information bits and a scrambling subcode for generating phase factors. Our proposed method is a suboptimal technique with low computation, because it uses a genetic algorithm with a partheno‐crossover operator as the transmitted signal selection mechanism. Simulation results show our proposed method has better PAPR performance than the GA‐PTS scheme. Based on the simulation results in Figures 5 and 6, it is evident that our proposed method can be employed in any OFDM system by using M‐PSK modulation.Copyright © 2013 John Wiley & Sons, Ltd.     

Peak‐to‐average power ratio reduction of a hidden training sequence‐aided precoding scheme for MIMO‐OFDM

We analyze a peak‐to‐average power ratio (PAPR) reduction property based on a hidden training sequence‐aided precoding scheme for MIMO‐OFDM systems. In addition to the benefits of a hidden training sequence‐aided precoding scheme such as improvement in bandwidth efficiency and frequency diversity gain, we address that power amplifier efficiency can be improved without any additional complexity burden. By mathematically analyzing PAPR of the precoded MIMO‐OFDM signal with a hidden training sequence, we demonstrate that PAPR reduction can be obtained by varying the allocated power to the hidden training sequence. Because of the low PAPR property of this scheme, it is possible to utilize a low‐cost power amplifier, resulting in the reduction in the total cost for hardware implementation. Copyright © 2014 John Wiley & Sons, Ltd.     

A novel search method to reduce PAPR of an OFDM signal using partial transmit sequences

One of the main drawbacks of orthogonal frequency division multiplexing (OFDM) is the high peak‐to‐average power ratio (PAPR) of the transmitted OFDM signal. Partial transmit sequence (PTS) technique can improve the PAPR statistics of an OFDM signal. As ordinary PTS technique requires an exhaustive search over all combinations of allowed phase factors, the search complexity increases exponentially with the number of sub‐blocks. In this paper, we propose a novel PTS technique with reduced complexity that each level inverts twice of phase factor bits from previous level. Then we also use initial random phase sequence to find the better search way of PAPR reduction. Numerical results show that the proposed method can achieve significant reduction in search complexity with little performance degradation. Copyright © 2006 John Wiley & Sons, Ltd.     

A novel ant colony optimization algorithm for PAPR reduction of OFDM signals

The high peak‐to‐average power ratio (PAPR) is the main challenge of orthogonal frequency division multiplexing (OFDM) systems. Partial transmit sequence (PTS) is a useful approach to diminish the PAPR. Although the PTS approach significantly decreases the PAPR, it requires to explore all possible sequences of phase weighting factors. Hence, the computational cost exponentially increases with the number of divided subblocks. This paper proposes a novel PTS technique based on ant colony optimization (ACO) to diminish the high PAPR and computational cost of OFDM systems. By the new representation of phase factors as a graph, the improved ACO algorithm is combined with the PTS method to explore the optimal compound of the phase rotation factors. Simulation results represent that the proposed ACO‐based PTS approach significantly reduces the PAPR and improves the computational cost at the same time. A comparative analysis of the other meta‐heuristics shows that the ACO‐PTS approach outperforms the genetic algorithm, particle swarm optimization, and gray wolf optimization in terms of reducing PAPR.     

Combination of PAPR reduction and linearization for the OFDM communication system

Orthogonal frequency division multiplexing (OFDM) has been widely used in many kinds of communication systems. However, OFDM signal has serious problem of high peak‐to‐average‐power ratio (PAPR) due to so many sub‐carriers. So, OFDM signal has very wide dynamic range. Therefore, the bit error rate (BER) performance may be degraded because of the nonlinear devices like the high power amplifier (HPA). Even if the linearization and large back‐off are used to compensate for the HPA nonlinearity, the power efficiency of the HPA is still very low since the PAPR is very high. Therefore, the PAPR reduction of the OFDM signal before the linearization would be more reasonable to improve the power efficiency and nonlinear compensation at the same time. In this paper, we propose a new combined method of SPW (sub‐block phase weighting) for PAPR reduction and linearization technique for the improvement of the power efficiency and for the nonlinear compensation of HPA. An updated SPW method is proposed to use a novel weighting factor multiplication of the complementary sequence characteristic and PAPR threshold technique. From the simulation results, it can be confirmed that BER performance is significantly improved and out‐of‐band spectrum radiations are much mitigated. Power efficiency of HPA can be enhanced since we can set small IBO (input back‐off) due to the PAPR reduction. The proposed system shows about 3 and 1 dB performance improvement than the LCP (linearized constant peak‐power)‐OFDM and LCP‐OFDM plus SPW at BER = 10⁻⁴. Copyright © 2010 John Wiley & Sons, Ltd.     

一种基于星座协作映射的改进P-OFDM方法

针对室内高速光无线链路设计,提出了一种新的光正交频分复用技术方案——改进极性光正交频分复用(MP-OFDM)。通过将星座协作映射技术引入到极性光OFDM(P-OFDM)系统中,在获得高效的功率和频谱利用率、较低峰均平均功率比(PAPR)及较好误码性能的同时,还可以进一步提高系统编码增益,增加系统设计自由度。仿真实验表明,与P-OFDM技术相比,该方案的PAPR性能与其接近,而平均误码块率性能则优于前者,即MP-OFDM系统可在不牺牲PAPR的同时获得更好的平均误码块率性能。同时,在功率分配方案中,系统能在平均误码块率性能与PAPR性能之间取得更好的折衷。     

Hybrid Zadoff‐Chu and multilateral piecewise exponential companding transform–based PAPR reduction technique in OFDM systems

The orthogonal frequency‐division multiplexing (OFDM) is a multicarrier modulation system that is used to transmit the large volume of data to the receiver. Reducing the peak‐to‐average power ratio (PAPR) in OFDM system is one of the demanding and crucial task in recent days. For this reason, various precoding and companding mechanisms are developed in the traditional works, but it remains with the limitations of increased complexity, reduced performance, and nonlinear distortion. The reduction of PAPR is achieved by minimizing the companding distortion with the enhancement of the bit error rate (BER) performance significantly. Then, in order to avoid clipping in OFDM, a multilateral piecewise exponential companding transform (MPECT) method has been utilized rather than using piecewise exponential companding transform (PEC) where PAPR is getting reduced. The OFDM is very sensitive to synchronizing error. To overcome this sensitivity, employ the Zadoff‐Chu sequence to carrier frequency offsets. Zadoff‐Chu matrix transform (ZCMT) has numerous merits among the other ODFM systems such as the improvement in the performance of the channels that are fading away and provides an ideal periodic autocorrelation and a constant magnitude periodic cross correlation. Both of these techniques provide improvement in the ODFM systems. To get more efficiency, this paper aims to develop a hybrid technique by integrating the ZCMT and MPECT techniques for reducing the PAPR in OFDM systems. Further, convolutional encoding is applied for better BER and PAPR. The simulation results of the proposed ZCMT‐MPECT technique are evaluated and compared with the conventional OFDM and other precoding methods.     

Peak‐to‐Average Power Ratio Reduction Using N‐tuple Selective Mapping Method for MC‐CDMA

The multi‐carrier transmission signal in Multi‐Carrier Code Division Multiple Access (MC‐CDMA) has a high peak‐to‐average power ratio (PAPR), which results in nonlinear distortion and deteriorative system performance. An n‐tuple selective mapping method is proposed to reduce the PAPR, in this paper. This method generates 2ⁿ sequences of an original data sequence by adding n‐tuple of n PAPR control bits to it followed by an interleaver and error‐control code (ECC) to reduce its PAPR. The convolutional, Golay, and Hamming codes are used as ECCs in the proposed scheme. The proposed method uses different numbers of the n PAPR control bits to accomplish a noteworthy PAPR reduction and also avoids the need for a side‐information transmission. The simulation results authenticate the effectiveness of the proposed method.     

Selected mapping with symbol re‐mapping for OFDM/TDM using MMSE‐FDE

Orthogonal frequency division multiplexing (OFDM) signals have a problem with a high peak‐to‐average power ratio (PAPR). A distortionless selected mapping (SLM) has been proposed to reduce the PAPR, but a high computational complexity prohibits its application to an OFDM system with a large number of subcarriers. Recently, we proposed OFDM combined with time division multiplexing (OFDM/TDM) using minimum mean square error frequency‐domain equalization (MMSE‐FDE) to improve the bit error rate (BER) performance of conventional OFDM with a lower PAPR. The PAPR problem, however, cannot be completely eliminated. In this paper, we present an SLM combined with symbol re‐mapping for OFDM/TDM using MMSE‐FDE. Unlike the conventional OFDM, where SLM is applied over subcarriers in the frequency domain, we exploit both time and frequency dimensions of OFDM/TDM signal to improve the performance with respect to PAPR and BER. A mathematical model for PAPR distribution of OFDM/TDM with SLM is presented to complement the computer simulation results. It is shown that proposed SLM can further reduce the PAPR without sacrificing the BER performance with the same or reduced computational complexity. Copyright © 2010 John Wiley & Sons, Ltd.     

Companding schemes based on transforming signal statistics into trigonal distributions for PAPR reduction in OFDM systems

This paper proposes four companding transforms to reduce the peak‐to‐average power ratio in orthogonal frequency division multiplexing systems. The four companding transforms are obtained by transforming signal statistics into four trigonal distributions. Computer simulations show that the proposed schemes can effectively improve the PAPR performance and bit error rate performance of OFDM systems. Copyright © 2010 John Wiley & Sons, Ltd.     

Dual symbol optimization‐based partial transmit sequence technique for PAPR reduction in WOLA‐OFDM waveform

Weighted overlap and add‐orthogonal frequency division multiplexing (WOLA‐OFDM) is a new waveform proposed recently for meeting the requirements of fifth generation (5G) telecommunication standards. In spite of being a serious 5G waveform candidate, WOLA‐OFDM is exposed to the problem of high peak to average power ratio (PAPR) similar to the other waveforms in which multicarrier transmission strategy is employed. Due to the overlapping nature of WOLA‐OFDM waveform, where the extension of the current symbol is overlapped with the extension of the previous symbol, it will not be efficient to apply conventional PTS (C‐PTS) directly to the WOLA‐OFDM waveform. Therefore, in this paper, we propose dual symbol optimization‐based partial transmit sequence (DSO‐PTS) technique for PAPR reduction in WOLA‐OFDM waveform. In our proposed technique, two adjacent symbols are jointly considered when searching for the optimal data block with minimum PAPR unlike the C‐PTS where the adjacent symbols are optimized individually. In the simulations, our proposed DSO‐PTS technique, C‐PTS, and GreenOFDM that is developed recently by modifying the conventional selective mapping (SLM) method are compared with each other with regard to PAPR reduction performance for different search numbers (SNs). In addition, the effects of DSO‐PTS, C‐PTS, and GreenOFDM on the amount of out of band (OOB) radiation in the power spectral density (PSD) graph of WOLA‐OFDM employing solid state power amplifier (SSPA) is measured for different SNs and input back off (IBO) values. According to the simulation results, our proposed DSO‐PTS technique clearly demonstrates a superior PAPR reduction and PSD performance.     

Research on the algorithm for reducing the PAPR of OFDM system based on quantum chaotic mapping

Aiming at the high peak to average power ratio (PAPR) problem of OFDM system,a modified selective mapping algorithm based on quantum loigstic chaotic map was proposed.To solve the problem of fixed point and stable window,the quantum loigstic chaotic maps were used as random phase sequence vectors,which provided a large number signals with fine correlation and random characteristics,easy to produce and regenerate.Matlab simulation results show that the proposed algorithm effectively reduces the PAPR,increases the numbers of candidate signals,cuts down the amount of redundant information transmission,bring down the side band power.The proposed scheme has a broad application prospect in OFDM system.     

A low‐complexity companding technique using Padé approximation for PAPR reduction of an OFDM system

Orthogonal Frequency Division Multiplexing (OFDM) systems have become the most promising wireless communication systems in the recent years. For OFDM systems, there is one major drawback, which is the high peak‐to‐average power ratio (PAPR). Companding techniques have been frequently proposed to reduce PAPR. Exponential companding technique offers efficient PAPR reduction with a low bit error rate (BER). However, the exponential companding technique is difficult to implement. This paper utilizes the Padé approximation to simplify the exponential companding technique. The simulation results demonstrate that the proposed companding technique offers the same performance results as those of the exponential companding technique, while Additive White Gaussian Noise (AWGN) or multipath fading channel is considered. Further, the hardware implementation results show that the complexity of the proposed companding technique is less than that of the exponential companding technique. Copyright © 2011 John Wiley & Sons, Ltd.     

SLM‐based PAPR reduction method using partial data circulation and side information insertion in OFDM systems

In this paper, two selected mapping (SLM)‐based schemes are proposed to reduce the peak‐to‐average power ratio (PAPR) in the orthogonal frequency division multiplexing (OFDM) systems. One is SLM‐based partial data circulation (PDC) scheme. The other is SLM‐based PDC with hamming coded side information (SI) scheme. In the PDC scheme, the partial samples within the data sequence are scrambled by circularly shifting to obtain a set of candidate sequences and, then, each sequence is combined with the corresponding SI to form the candidate OFDM symbol. With the selection of the candidate OFDM symbols with the lowest PAPR, the PAPR of the transmitted signal could be greatly reduced. In the other scheme, hamming code is used to protect the SI to improve the system performance. Simulation results show that the proposed method could reduce PAPR and it has a better bandwidth efficiency and less modules of inverse fast Fourier transform than that with the SLM‐based dummy sequence insertion scheme. Copyright © 2008 John Wiley & Sons, Ltd.     

一种降低OFDM系统峰均比的改进算法

选择映射（SLM）技术是一种无失真降低正交频分复用（OFDM）系统信号峰均比的方法,为更好地降低正交频分复用系统的峰均比,文中提出了一种基于SLM级联抵消技术降低PAPR的优化算法。该算法首先利用改进的SLM算法,对系统PAPR特性进行优化,然后利用抽样信号作为参考函数,实现对系统峰均比的有效降低。通过分析SLM级联峰...     

正交频分复用信号峰均比抑制技术研究

正交频分复用(OFDM)系统存在峰值平均功率比(PAPR)较高的缺点.通过对PAPR相关特性的深入讨论分析,针对峰值抵消波峰因子降低(PC?CFR)算法引入的非线性失真较大的问题,提出了一种可降低信号非线性失真的峰均比抑制算法,即PC?CFR算法与部分传输序列(PTS)算法联合改进的PAPR抑制方案.仿真结果表明,该方...     

A study on the PAPRs in multicarrier modulation systems with different orthogonal bases

This paper studies the peak‐to‐average power ratios (PAPRs) in multicarrier modulation (MCM) systems with seven different orthogonal bases, one Fourier base and six wavelet bases. It is shown by simulation results that the PAPRs of the Fourier‐based MCM system are lower than those of all wavelet‐based MCM (WMCM) systems. A novel threshold‐based PAPR reduction method is then proposed to reduce the PAPRs in WMCM systems. Both numerical and simulation results indicate that the proposed PAPR reduction method works very effectively in WMCM systems. Copyright © 2006 John Wiley & Sons, Ltd.     

OFDM系统中基于限幅和压缩感知的非线性失真补偿算法

正交频分复用（Orthogonal Frequency Division Multiplexing,OFDM）信号具有较高的峰均功率比（Peak to Average Power Ratio,PAPR）,不仅影响功率放大器（High Power Amplifier,HPA）的工作效率,而且HPA使得OFDM信号产生严重的非线性失真,导致系统的误比特率（Bite Error Rate,BER）增大.本文基于限幅和压缩感知（Compressive Sensing,CS）提出了改进的补偿算法,发送端采用限幅降低信号的PAPR,接收端首先采用改进的逆模型方式减小HPA引入的非线性失真,再采用CS抵消由限幅引入的信号失真.仿真表明,所提方法不仅明显降低了OFDM信号的PAPR,而且有效提高了系统的BER性能.     

Computationally efficient variational Bayesian method for PAPR reduction in multiuser MIMO‐OFDM systems

This paper investigates the use of the inverse‐free sparse Bayesian learning (SBL) approach for peak‐to‐average power ratio (PAPR) reduction in orthogonal frequency‐division multiplexing (OFDM)‐based multiuser massive multiple‐input multiple‐output (MIMO) systems. The Bayesian inference method employs a truncated Gaussian mixture prior for the sought‐after low‐PAPR signal. To learn the prior signal, associated hyperparameters and underlying statistical parameters, we use the variational expectation‐maximization (EM) iterative algorithm. The matrix inversion involved in the expectation step (E‐step) is averted by invoking a relaxed evidence lower bound (relaxed‐ELBO). The resulting inverse‐free SBL algorithm has a much lower complexity than the standard SBL algorithm. Numerical experiments confirm the substantial improvement over existing methods in terms of PAPR reduction for different MIMO configurations.