一种降低正交频分复用峰均功率比的方法

目前正交频分复用（OFDM）正得到越来越广泛的应用，但其主要缺点是有较高的峰均比（PAPR），虽然有许多降低OFDM信号的峰均比的方案，但是却大大增加了系统的复杂性，本文通过改进一种降低OFDM信号峰均功率的方法，很好地解决了复杂性和峰均比的降低的问题。     

基于分组格雷编码的OFDM 雷达通信一体化系统峰均功率比抑制

基于OFDM 共享信号的雷达通信一体化系统具有较高的峰均功率比,由于编码率的限制,采用格雷序列编码抑制系统峰均功率比(PAPR)的算法只适合应用于子载波数较少的场合。针对子载波数较多的系统,该文提出一种利用分组并行格雷编码结合系数加权优化的PAPR 抑制算法,通过将输入比特流分为若干组并行比特,分别进行格雷序列编码、数据符号调制以及逆傅里叶变换,将结果合并就可以得到一个OFDM 符号。在合并之前对每一组引入若干加权系数,这样就构成了多个可供选择的OFDM 符号,通过选择具有最小PAPR 值的OFDM 符号作为发射信号,实现系统PAPR 抑制。最后,仿真了3 种不同分组方案下PAPR 抑制能力、通信误码率以及雷达宽带模糊函数,仿真结果表明,该算法可有效抑制系统PAPR,降低系统误码率,其雷达宽带模糊函数仍为近似图钉型,具有良好的距离和速度分辨能力以及测距、测速精度。      

降低16QAM-OFDM信号峰均功率比的方法研究

针对0FDM峰均功率比(PAPR)问题,提出利用Golay互补序列(GCS)降低16QAM-0FDM信号PAPR的方法,分析了其PAPR最大值、16QAM序列集合大小以及编码率,讨论了编译码算法和纠错能力.研究结果表明,这些降低PAPR的方法在系统设计有不同要求时具有不同先决应用条件.     

降低OFDM系统峰均功率比的研究

对载波干涉技术降低OFDM的峰均功率比方法进行改进。先对输入信号进行分组,使系统峰值功率得到明显降低,之后再对分组后的信号进行载波干涉。理论分析及仿真结果表明,提出的方法能使系统峰值功率有明显降低,进而达到了进一步的降低峰均功率比的目的。该方法算法简单、不产生失真,不用传送边带信息,易于与其他降低PAPR的技术相结合使用,具有较好的实用性。     

一种抑制PAPR信号峰均功率比的有效方法

OFDM技术的应用越来越广泛,但是其发送信号功率的峰均功率比（PAPR）比较大是其主要的缺陷之一。本文提出了一个降低OFDM信号PAPR的有效灵活的技术。该方法是通过恰当的选择OFDM调制中各个子载波的时域脉冲波形。仿真结果表明该方法能够大大降低OFDM信号的PAPR值。该技术与现有的其他方法相比实现复杂度也更低。     

降低OFDM峰均功率比技术综述

OFDM是一种多载波调制技术，其特有的调制特性决定了它有较高的峰均功率比值，高峰均功率比信号会对实际放大器提出很高的线性要求，因此它是限制OFDM技术实用化的主要障碍，本文总结了目前降低OFDM峰均功率比的研究成果。     

次随机分块PTS-Clipping峰均比抑制算法

针对正交频分复用信号存在高峰均比问题,本文提出了一种基于次随机分块的部分传输序列(partial transmit se-quence,PTS)与传统限幅剪切联合处理的峰均比抑制算法.该算法在时域得到随机分块的子块序列,子块序列乘以相位旋转因子得到多个备选序列,从多个备选序列中寻找低峰值OFDM信号,最后利用频域滤波剪切算法限幅.仿真结果表明,所提算法在低复杂度下可以有效降低PAPR.     

降低OFDM系统峰均功率比的方法

针对正交频分复用系统,提出了一种复杂度较低的降低峰均功率比的方法.该方法首先实施时域过采样,再采用功率归一化和限幅,最后对限幅后的信号进行低通滤波.此外,从信噪比和信号噪声失真比等角度分析了限幅对过采样OFDM信号的影响.仿真结果表明,与传统的限幅滤波方法对比,该方法能有效抑制滤波后系统峰均功率比的回升.     

一种抑制OFDM信号峰均功率比的新优化算法

为了降低正交频分复用系统的峰均比,提出了一种将部分传输序列（PTS）算法与限带抵消技术相级联的新算法。该算法首先利用F1S算法,对系统PAPR特性优化,然后利用限带抽样信号作为参考函数,实现对系统峰均功率比的进一步有效降低。文中给出PTS级联抵消技术的原理和算法,并分析了在不同抵消程度基础上系统的PAPR性能。仿真结果表明,此种方法仅以微小的误码率性能为代价,有效降低正交频分复用系统的峰均功率比。     

减少OFDM信号的峰均功率比的PTS方法

正交频分复用(OFDM)技术的一个主要缺点是有很高的峰均功率比(PAPR)，目前已有许多用来降低OFDM信号峰均功率比的方法，部分传输序列(PTS)就是其中之一，此外，它还可以改善OFDM信号的峰均功率比的性能。本文对部分传输序列（PTS）的方法进行了描述，并且提出了一种减小复杂度的方法。     

降低OFDM峰值平均功率比的方法

正交频分复用(OFDM)作为一种抗多径的高速信息传输技术，最大缺点就是固有的高峰值平均功率比。综述了现有的用于降低OFDM系统中峰值平均功率比的方法及其存在的问题。     

Efficient implementation of complementary Golay sequences for PAR reduction and forward error correction in OFDM-based WLAN systems

In this paper the use of complementary Golay sequences (CGS) for peak-to-average power ratio (PAR) reduction and forward error correction (FEC) in an orthogonal frequency division multiplexing (OFDM)-based wireless local area network (WLAN) system is explored; performance is examined and complexity issues are analyzed. We study their PAR reduction performance depending on sequence lengths and we have found that, for the case that the number of sub-carriers differs from the sequence length, some interesting relationships can still be stated. Regarding their error correction capabilities, these sequences are investigated considering M-PSK constellations applied to the OFDM signal specified in IEEE 802.11a standard. Computational load for both Golay encoding and decoding processes is addressed and we provide an exhaustive analysis of their complexity. In order to overcome memory restrictions and speed up algorithmic operations, a novel algorithm for real-time generation of the Golay Base Sequences is proposed and evaluated giving as a conclusion that these sequences can be real-time generated with actual Digital Signal Processors (DSP). Our proposal lies on an efficient permutation algorithm that obtains the current permutation without the need for generating previous ones. Its complexity is calculated and turns out to be significantly low; the advantages are specially appreciated at the decoding stage. We also introduce a hybrid solution to get a trade-off between complexity and memory requirements. Moreover, the whole system is also implemented in a DSP to validate the proposal in a prototype, where its feasibility has been confirmed.     

降低FSO-OFDM系统峰值平均功率比研究

虽然OFDM调制技术在射频领域中已得到了广泛的研究,但在无线光领域中的研究才刚开始.由于FSO-OFDM系统中采用马赫-曾德尔(MZM)调制器进行电光转换,该调制器的转移特性曲线为余弦函数,存在很大的非线性问题,因此,FSO-OFDM系统比射频OFDM系统对PAPR更加敏感.为了降低系统PAPR,重点研究了基于Gola...     

A phase scrambling scheme for suppression of peak to average power ratio for OFDM

The complex-valued modulating vectors for the subcarrlers consist of two kinds of components: One is the information-bearing components superposed with pseudo-randomized phases and the other is the suppression components with specified scrambling phases. The pseudorandomized phases are generated according to the predefined polynomial and mapping function whereas the scrambling phases are from a gradient algorithm. The simulation results verify the rationality and validity of the phase scrambling.     

降低OFDM系统高峰均功率比的方法研究

针对OFDM技术具有较高的峰均功率比（peak to average power ration,PAPR）这一主要缺点,提出一种控制OFDM载波信号衍生频谱的迭代算法,在降低系统高峰均功率比的同时,也降低系统的误码率.利用该算法对数据序列长度为64的OFDM信号进行仿真验证,随着迭代次数的增加,衍生频谱系数增大,系统平均功率增加,OFDM信号的峰值功率比得到一定的降低.     

A low complexity selected mapping scheme for peak to average power ratio reduction with digital predistortion in OFDM systems

One of the effective methods used for reducing peak‐to‐average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems is selected mapping (SLM). In this paper, a new SLM scheme called DSI‐SLM, which is a combination of dummy sequence insertion (DSI) and conventional selected mapping (C‐SLM) is proposed. Previous techniques have had some drawbacks. In DSI, increasing the number of dummy sequences to have better PAPR degrades transmission efficiency, and in C‐SLM, the complexity rises dramatically when the number of sub‐blocks increases. The proposed DSI‐SLM scheme significantly reduces the complexity because of the reduction in the number of sub‐blocks compared with the C‐SLM technique while its PAPR performance is even better. To enhance the efficiency of the OFDM system and suppress the out‐of‐band distortion from the power amplifier nonlinearity, a digital predistortion technique is applied to the DSI‐SLM scheme. Simulations are carried out with the actual power amplifier model and the OFDM signal based on the worldwide interoperability for microwave access standard and quadrature phase‐shift keying modulation. The simulation results show improvement in PAPR reduction and complexity, whereas the BER performance is slightly worse. Copyright © 2011 John Wiley & Sons, Ltd.     

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

This 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.     

基于多相互补序列的多载波信号的峰值因子分析

针对具有相同幅度和等频率间隔的许多余弦函数组成的多载波信号，本文首先对它们的峰值因子上界进行了推导，得出它取决于由多载波信号初始相位组成的复序列的幅度谱。然后证明了由多相互补序列对中任-互补序列构成的多载波信号的峰值因子小于或等于6dB。最后，给出了由长度等于10的多相互补序列构成的多载波信号的两个仿真例子，结果表明它们的峰值因子在5-6dB之间，和理论分析相吻合。此外，还发现二进制Golay互补序列能够产生对称的多载波信号，该特性对于某些应用是很有用的。     

一种利用标准阵列降低PAPR的新方法

针对正交频分复用系统中峰均功率比较大的问题,从分析选择映射法的基本原理和实现框图入手,详细描述了利用线性分组码标准阵列降低OFDM系统PAPR的算法,其核心思想是通过选择陪集中PAPR较小的向量代替选择映射法中的加权向量。最后进行了蒙特卡罗仿真,仿真结果表明,该方法能够明显改善PAPR特性。