This paper proposes a linear companding transform(CT)using either a single inflection point or two inflection points to reduce the peakto-average power ratio(PAPR)in orthogonal timefrequency space(OTFS)signals.The CT ...This paper proposes a linear companding transform(CT)using either a single inflection point or two inflection points to reduce the peakto-average power ratio(PAPR)in orthogonal timefrequency space(OTFS)signals.The CT strategically compresses higher amplitudes and enhances lower amplitudes based on carefully chosen scaling factors and points of inflection.With these selected parameters,the CT effectively reduces peak power while maintaining average power,leading to a substantial decrease in PAPR.We analyze noise changes in the inverse companding transform(ICT)process.The analysis reveals that the ICT amplifies less than 20%of the total noise.A convolutional encoder and soft decision Viterbi decoding algorithm are utilized in the OTFS system to improve the detection performance.We present simulation results focusing on PAPR reduction and bit error rate(BER)performance.These results demonstrate that the CT with two inflection points outperforms both the single inflection point case and the existingμ-law companding,clipping,peak windowing,unique OTFS frame structure,selected mapping,and partial transmit sequence methods,achieving significant PAPR reduction and BER performance.展开更多
In this paper,a novel efficient continuous piecewise nonlinear companding scheme is proposed for reducing the peak-to-average power ratio(PAPR)of orthogonal frequency division multiplexing(OFDM)systems.In the proposed...In this paper,a novel efficient continuous piecewise nonlinear companding scheme is proposed for reducing the peak-to-average power ratio(PAPR)of orthogonal frequency division multiplexing(OFDM)systems.In the proposed companding transform,signal samples with large amplitudes is clipped for peak power reduction,and the signal samples with medium amplitudes is nonlinear transformed with power compensation.While the signal samples with small amplitudes remain unchanged.The whole companding function is continuous and smooth in the range of positive numbers,which is beneficial for guaranteeing the bit error rate(BER)and power spectral density(PSD)performance.This scheme can achieve a significant reduction in PAPR.And at the same time,it cause little increment in BER and PSD performance.Simulation results indicate the superiority of the proposed scheme over existing companding schemes.展开更多
A wavelet collocation method with nonlinear auto companding is proposed for behavioral modeling of switched current circuits.The companding function is automatically constructed according to the initial error distri...A wavelet collocation method with nonlinear auto companding is proposed for behavioral modeling of switched current circuits.The companding function is automatically constructed according to the initial error distribution obtained through approximating the input output function of the SI circuit by conventional wavelet collocation method.In practical applications,the proposed method is a general purpose approach,by which both the small signal effect and the large signal effect are modeled in a unified formulation to ease the process of modeling and simulation.Compared with the published modeling approaches,the proposed nonlinear auto companding method works more efficiently not only in controlling the error distribution but also in reducing the modeling errors.To demonstrate the promising features of the proposed method,several SI circuits are employed as examples to be modeled and simulated.展开更多
The μ-law companding function has been applied widely in orthogonal frequency division multiplexing (OFDM) to reduce the peak-to-average power ratio (PAPR). However, nonlinear distortion caused by the μ-law compandi...The μ-law companding function has been applied widely in orthogonal frequency division multiplexing (OFDM) to reduce the peak-to-average power ratio (PAPR). However, nonlinear distortion caused by the μ-law companding function is considered a key impairment in OFDM communication systems. Few studies have addressed theoretical nonlinear distortion caused by μ-law companding function for OFDM systems. In this paper, we derive a closed-form expression of signal distortion as well as the closed-form bit error rate (BER) of OFDM system caused by the μ-law companding function. Based on the theoretical signal distortion and BER expression, the theoretical BER value and signal distortion value can also be calculated, which can guide us to choose appropriate μ value for different BER condition and bit-to-noise (Eb/N0) condition efficiently. Then the PAPR performance can also be predicted. The results show good agreement on the Monte-Carlo simulation results and the obtained theoretical BER results. Furthermore, based on theoretical signal distortion and theoretical BER expression, the figure of the relationship among BER value, Eb/N0 and μ is also given. Based on this figure, we can find the appropriate μ law for different BER and Eb/N0 condition. And then the PAPR performance can also be predicted.展开更多
In this paper, a novel nonlinear companding transform(NCT) is proposed to reduce the Peak-to-Average Power Ratio(PAPR) of orthogonal frequency division multiplexing(OFDM) signals. The companding function is designed b...In this paper, a novel nonlinear companding transform(NCT) is proposed to reduce the Peak-to-Average Power Ratio(PAPR) of orthogonal frequency division multiplexing(OFDM) signals. The companding function is designed based on continuously differentiable reshaping of the probability density function(PDF) of signal amplitudes. The original PDF is cut off for PAPR reduction, and lower and medium segments of original PDF are scaled and linearized respectively, for maintaining power and cumulative distribution constraints. The linearized segment is set to be the tangent of the scaled version at the inflexion point, so as to reduce the out-ofband(OOB) radiation as much as possible. Parameters of the proposed scheme are solved under joint constraints of constant power and unity cumulative distribution. A new receiving method is also proposed to improve the bit error rate(BER) performance of OFDM systems. Simulation results indicate the proposed scheme can achieve better OOB radiation and BER performance at same PAPR levels, compared with existing similar companding algorithms.展开更多
The high peak-to-average (PAPR) is one of the serious problems in the application of OFDM technology. The com-panding transform approach is a very attractive technique to reduce PAPR, but large PAPR reduction leads to...The high peak-to-average (PAPR) is one of the serious problems in the application of OFDM technology. The com-panding transform approach is a very attractive technique to reduce PAPR, but large PAPR reduction leads to a high bit error rate (BER) by the available companding transform techniques. In this paper, a joint reduction in PAPR of the OFDM signals based on combining the discrete cosine transform (DCT) with companding is proposed. In the first step of the proposed scheme, the data are transformed by a DCT into new modified data. In the second step, the proposed scheme utilizes the companding technique to further reduce the PAPR of the OFDM signal. The performance of the PAPR is evaluated using a computer simulation. The simulation results indicate that the proposed scheme may obtain about 1 dB PAPR reduction compared with the conventional companding algorithm.展开更多
广义频分复用(Generalized Frequency Division Multiplexing,GFDM)系统的灵活调制特性使其应用于低轨(Low Earth Orbit,LEO)卫星通信系统中可以带来诸多增益,但多个调制符号的叠加,导致GFDM的高峰均功率比(Peak-to-Average Power Ratio...广义频分复用(Generalized Frequency Division Multiplexing,GFDM)系统的灵活调制特性使其应用于低轨(Low Earth Orbit,LEO)卫星通信系统中可以带来诸多增益,但多个调制符号的叠加,导致GFDM的高峰均功率比(Peak-to-Average Power Ratio,PAPR)问题。针对此问题,在分析GFDM系统PAPR产生的原因后,对传统选择性映射(Conventional Selective Mapping,C-SLM)算法做出改进,利用Logistic混沌序列代替传统相位因子,解决边带信息冗余问题,采用线性重组的方式,进一步生成更多的备选信号,得到基于Logistic混沌序列的低复杂度选择性映射(Low Complexity SLM Based on Logistic Chaotic Sequences,LC-SLM)算法。在利用LC-SLM算法破坏符号间的相位一致性后,为解决单一算法对GFDM系统PAPR抑制不足的问题,将LC-SLM算法与指数压扩算法结合,提出一种低复杂度选择性映射联合指数压扩(LC-SLM with Exponential Companding,LC-SLM-EC)算法,使系统的PAPR进一步降低。实验结果表明,LC-SLM算法与生成相同数量备选信号的C-SLM算法相比,在大幅降低运算复杂度的前提下具有相近的PAPR性能,提出的LC-SLM-EC算法能够在不提升复杂度的基础上,使PAPR抑制效果更优。展开更多
Piecewise companding transform is a flexible and efficient way to solve the high peak-to-average power ratio （PAPR） problem for orthogonal frequency division multiplexing （OFDM） systems. A novel threshold-based pi...Piecewise companding transform is a flexible and efficient way to solve the high peak-to-average power ratio （PAPR） problem for orthogonal frequency division multiplexing （OFDM） systems. A novel threshold-based piecewise companding transform is proposed in this paper. Based on the statistical characteristics of amplitudes, OFDM signals are classified into three groups （i.e., small, average and large signals）. Different from conventional approaches, two dedicated designed thresholds are set to amplify the small signals and compress the large signals, respectively. Simulation results verify the improvement in PAPR reduction of the proposed scheme. Moreover, a lower bit error rate （BER） performance loss can be obtained by introducing the iterative detection with a moderate increase in complexity.展开更多
Orthogonal frequency division multiplexing(OFDM)produces a high peak-to-average power ratio(PAPR) that adversely affects high-speed OFDM data transmission. In order to reduce the high PAPR, an efficient nonlinear comp...Orthogonal frequency division multiplexing(OFDM)produces a high peak-to-average power ratio(PAPR) that adversely affects high-speed OFDM data transmission. In order to reduce the high PAPR, an efficient nonlinear companding transform(NCT) function is proposed. With the proposed NCT function,the compression and expansion weights can be applied independently with suitably chosen function parameter values. As a result, the proposed function can easily maintain the average signal power approximately unchanged during the companding process.In this regard, the proposed function is superior to previously proposed schemes. Also, the simulations show the outstanding PAPR reduction performance of the proposed function. It is demonstrated that the proposed scheme performs well with nonlinear transmitter amplifiers and delivers superior error performance, compared with error function and exponential function based schemes.展开更多
正交时频空间(Orthogonal Time Frequency Space)是近年来兴起的一种新型多载波调制技术。与正交频分复用(Orthogonal Frequency Division Multiplexing)一样,OTFS也存在峰均比(Peak to Average Power Ratio)过高的问题。为此,论文尝试...正交时频空间(Orthogonal Time Frequency Space)是近年来兴起的一种新型多载波调制技术。与正交频分复用(Orthogonal Frequency Division Multiplexing)一样,OTFS也存在峰均比(Peak to Average Power Ratio)过高的问题。为此,论文尝试将μ律压扩滤波器应用与OTFS系统。将发送端经过海森堡变换的信号中进行μ律压扩变换,且在接收端进行反压扩恢复原始信号,以降低PAPR。仿真结果表明,在OTFS中应用μ律压扩滤波器,在显著降低PAPR的同时,对误码率性能影响较小,且易于工程实现。展开更多
文摘This paper proposes a linear companding transform(CT)using either a single inflection point or two inflection points to reduce the peakto-average power ratio(PAPR)in orthogonal timefrequency space(OTFS)signals.The CT strategically compresses higher amplitudes and enhances lower amplitudes based on carefully chosen scaling factors and points of inflection.With these selected parameters,the CT effectively reduces peak power while maintaining average power,leading to a substantial decrease in PAPR.We analyze noise changes in the inverse companding transform(ICT)process.The analysis reveals that the ICT amplifies less than 20%of the total noise.A convolutional encoder and soft decision Viterbi decoding algorithm are utilized in the OTFS system to improve the detection performance.We present simulation results focusing on PAPR reduction and bit error rate(BER)performance.These results demonstrate that the CT with two inflection points outperforms both the single inflection point case and the existingμ-law companding,clipping,peak windowing,unique OTFS frame structure,selected mapping,and partial transmit sequence methods,achieving significant PAPR reduction and BER performance.
基金supported in part by the National Natural Science Foundation of China(No.61821001)。
文摘In this paper,a novel efficient continuous piecewise nonlinear companding scheme is proposed for reducing the peak-to-average power ratio(PAPR)of orthogonal frequency division multiplexing(OFDM)systems.In the proposed companding transform,signal samples with large amplitudes is clipped for peak power reduction,and the signal samples with medium amplitudes is nonlinear transformed with power compensation.While the signal samples with small amplitudes remain unchanged.The whole companding function is continuous and smooth in the range of positive numbers,which is beneficial for guaranteeing the bit error rate(BER)and power spectral density(PSD)performance.This scheme can achieve a significant reduction in PAPR.And at the same time,it cause little increment in BER and PSD performance.Simulation results indicate the superiority of the proposed scheme over existing companding schemes.
文摘A wavelet collocation method with nonlinear auto companding is proposed for behavioral modeling of switched current circuits.The companding function is automatically constructed according to the initial error distribution obtained through approximating the input output function of the SI circuit by conventional wavelet collocation method.In practical applications,the proposed method is a general purpose approach,by which both the small signal effect and the large signal effect are modeled in a unified formulation to ease the process of modeling and simulation.Compared with the published modeling approaches,the proposed nonlinear auto companding method works more efficiently not only in controlling the error distribution but also in reducing the modeling errors.To demonstrate the promising features of the proposed method,several SI circuits are employed as examples to be modeled and simulated.
基金supported by the National Natural Science Foundation of China(61821001/61272518)
文摘The μ-law companding function has been applied widely in orthogonal frequency division multiplexing (OFDM) to reduce the peak-to-average power ratio (PAPR). However, nonlinear distortion caused by the μ-law companding function is considered a key impairment in OFDM communication systems. Few studies have addressed theoretical nonlinear distortion caused by μ-law companding function for OFDM systems. In this paper, we derive a closed-form expression of signal distortion as well as the closed-form bit error rate (BER) of OFDM system caused by the μ-law companding function. Based on the theoretical signal distortion and BER expression, the theoretical BER value and signal distortion value can also be calculated, which can guide us to choose appropriate μ value for different BER condition and bit-to-noise (Eb/N0) condition efficiently. Then the PAPR performance can also be predicted. The results show good agreement on the Monte-Carlo simulation results and the obtained theoretical BER results. Furthermore, based on theoretical signal distortion and theoretical BER expression, the figure of the relationship among BER value, Eb/N0 and μ is also given. Based on this figure, we can find the appropriate μ law for different BER and Eb/N0 condition. And then the PAPR performance can also be predicted.
基金supported by National Natural Science Foundation of China(No.61821001)Science and Technology Key Project of Guangdong Province,China(2019B010157001)。
文摘In this paper, a novel nonlinear companding transform(NCT) is proposed to reduce the Peak-to-Average Power Ratio(PAPR) of orthogonal frequency division multiplexing(OFDM) signals. The companding function is designed based on continuously differentiable reshaping of the probability density function(PDF) of signal amplitudes. The original PDF is cut off for PAPR reduction, and lower and medium segments of original PDF are scaled and linearized respectively, for maintaining power and cumulative distribution constraints. The linearized segment is set to be the tangent of the scaled version at the inflexion point, so as to reduce the out-ofband(OOB) radiation as much as possible. Parameters of the proposed scheme are solved under joint constraints of constant power and unity cumulative distribution. A new receiving method is also proposed to improve the bit error rate(BER) performance of OFDM systems. Simulation results indicate the proposed scheme can achieve better OOB radiation and BER performance at same PAPR levels, compared with existing similar companding algorithms.
文摘The high peak-to-average (PAPR) is one of the serious problems in the application of OFDM technology. The com-panding transform approach is a very attractive technique to reduce PAPR, but large PAPR reduction leads to a high bit error rate (BER) by the available companding transform techniques. In this paper, a joint reduction in PAPR of the OFDM signals based on combining the discrete cosine transform (DCT) with companding is proposed. In the first step of the proposed scheme, the data are transformed by a DCT into new modified data. In the second step, the proposed scheme utilizes the companding technique to further reduce the PAPR of the OFDM signal. The performance of the PAPR is evaluated using a computer simulation. The simulation results indicate that the proposed scheme may obtain about 1 dB PAPR reduction compared with the conventional companding algorithm.
文摘广义频分复用(Generalized Frequency Division Multiplexing,GFDM)系统的灵活调制特性使其应用于低轨(Low Earth Orbit,LEO)卫星通信系统中可以带来诸多增益,但多个调制符号的叠加,导致GFDM的高峰均功率比(Peak-to-Average Power Ratio,PAPR)问题。针对此问题,在分析GFDM系统PAPR产生的原因后,对传统选择性映射(Conventional Selective Mapping,C-SLM)算法做出改进,利用Logistic混沌序列代替传统相位因子,解决边带信息冗余问题,采用线性重组的方式,进一步生成更多的备选信号,得到基于Logistic混沌序列的低复杂度选择性映射(Low Complexity SLM Based on Logistic Chaotic Sequences,LC-SLM)算法。在利用LC-SLM算法破坏符号间的相位一致性后,为解决单一算法对GFDM系统PAPR抑制不足的问题,将LC-SLM算法与指数压扩算法结合,提出一种低复杂度选择性映射联合指数压扩(LC-SLM with Exponential Companding,LC-SLM-EC)算法,使系统的PAPR进一步降低。实验结果表明,LC-SLM算法与生成相同数量备选信号的C-SLM算法相比,在大幅降低运算复杂度的前提下具有相近的PAPR性能,提出的LC-SLM-EC算法能够在不提升复杂度的基础上,使PAPR抑制效果更优。
基金supported by the National Natural Science Foundation of China(61072069)the Fundamental Research Funds for the Central Universities(72105242)the 111 Project(B08038)
文摘Piecewise companding transform is a flexible and efficient way to solve the high peak-to-average power ratio （PAPR） problem for orthogonal frequency division multiplexing （OFDM） systems. A novel threshold-based piecewise companding transform is proposed in this paper. Based on the statistical characteristics of amplitudes, OFDM signals are classified into three groups （i.e., small, average and large signals）. Different from conventional approaches, two dedicated designed thresholds are set to amplify the small signals and compress the large signals, respectively. Simulation results verify the improvement in PAPR reduction of the proposed scheme. Moreover, a lower bit error rate （BER） performance loss can be obtained by introducing the iterative detection with a moderate increase in complexity.
基金supported by the Research Grant of BB(Brain Busan)21 Project of 2015
文摘Orthogonal frequency division multiplexing(OFDM)produces a high peak-to-average power ratio(PAPR) that adversely affects high-speed OFDM data transmission. In order to reduce the high PAPR, an efficient nonlinear companding transform(NCT) function is proposed. With the proposed NCT function,the compression and expansion weights can be applied independently with suitably chosen function parameter values. As a result, the proposed function can easily maintain the average signal power approximately unchanged during the companding process.In this regard, the proposed function is superior to previously proposed schemes. Also, the simulations show the outstanding PAPR reduction performance of the proposed function. It is demonstrated that the proposed scheme performs well with nonlinear transmitter amplifiers and delivers superior error performance, compared with error function and exponential function based schemes.
文摘正交时频空间(Orthogonal Time Frequency Space)是近年来兴起的一种新型多载波调制技术。与正交频分复用(Orthogonal Frequency Division Multiplexing)一样,OTFS也存在峰均比(Peak to Average Power Ratio)过高的问题。为此,论文尝试将μ律压扩滤波器应用与OTFS系统。将发送端经过海森堡变换的信号中进行μ律压扩变换,且在接收端进行反压扩恢复原始信号,以降低PAPR。仿真结果表明,在OTFS中应用μ律压扩滤波器,在显著降低PAPR的同时,对误码率性能影响较小,且易于工程实现。
