一种降低CO-OFDM系统PAPR的PTS方法

为降低相干光正交频分复用(C0-0FDM)系统的峰均功率比(PAPR),对序列的实部和虚部分别独立应用部分传输序列(PTS)方法优化处理,并把迭代算法用于计算过程中,得到一种实部和虚部独立迭代优化的PTS方法.理论和仿真表明,该方法在有效减少计算量的同时又能获得较好的PAPR性能.     

一种基于格雷互补序列抑制峰均功率比的方法

正交频分复用(0FDM)信号调制中存在的高峰均功率比(PAPR)，为其实用化设置了障碍。具体分析了采用格雷互补序列和雷德密勒码来降低PAPR的算法，并用MATLAB进行了仿真，验证了当采用PSK调制时该编码方法可将PAPR降至3dB以下。     

一种减小OFDM信号峰均功率比的Coded-SLM算法

针对减小正交频分复用(0FDM)系统峰均功率比(PAPR)的常规选择性映射(SLM)法不仅运算量大,而且需要传送代表相位序列的边信息,因而降低了有效的传输效率的问题,提出了一种基于线性分组码的Coded-SLM算法.理论分析和计算机仿真都表明,该方法与常规SLM法相比虽然在降低PAPR方面稍微逊色,但与原始OFDM相比...     

降低复杂度的PTS方法及其在IEEE802．16a OFDM系统中的应用

部分传输序列(PTS)是一种复杂度较高的减小正交频分复用(OFDM)系统峰均功率比(PAPR)的方法。文中介绍了两种降低PTS复杂度的方法，一种是m序列PTS，另一种是迭代移位线性搜索法PTS。并将这两种方法应用到基于IEEE802．16a的OFDM系统中，仿真表明这两种方法都能够降低PTS的复杂度，同时减小系统的PAPR。     

降低OFDM系统PAPR概率类技术的研究

正交频分复用(OFDM)是第四代移动通信的核心技术.然而OFDM系统中存在较高的峰值平均功率比(PAPR),研究了选择性映射法(SLM)和部分传输序列法(PTS)两种方案降低OFDM系统的PAPR,并且研究了子载波和子信道数目对SLM和PTS算法改善PAPR性能的影响.仿真显示这两种算法都能够减少PAPR出现的概率,从而减小PAPR对OFDM通信系统性能的影响.     

降低可见光DCO-OFDM系统峰均比的DCT-GCS方法

为了克服现有降低OFDM峰值平均功率比的方法在可见光通信中效果不好的问题,通过分析发现DCO-OFDM系统输入序列的共轭对称形式增强了序列的相关性,使传统方法的PAPR抑制性能有明显下降,所以提出了离散余弦变换(DCT)与分组循环移位(GCS)结合的降低系统PAPR的方法。该方法中的分组循环移位能够在DCT的基础上降低输入序列的相关性,使系统输出信号具有更低的PAPR。仿真结果表明:提出的方法比仅采用DCT或者GCS能够更好地抑制系统的PAPR。在CCDF=10-4时,DCT-GCS方法使系统的PAPR下降了5.4dB。DCT-GCS具有较低的PAPR,且计算复杂度要远远低于PTS和SLM方法。      

降低OFDM系统中PAPR的次优化PTS算法

正交频分复用(OFDM)系统的主要缺点是峰均功率比(PAPR)增大会严重地降低了发射机中高功率放大器(HPA)的效率.部分传输序列(PTS)算法能有效地降低OFDM信号的PAPR概率,但随着PTS中分割子块的增多也带来了高的计算复杂度.为此,文中提出一种新的PTS算法,该算法比传统的穷尽搜寻法具有更佳的性能.仿真结果表明,文中所提PTS算法在降低PAPR相似的情况下,具有更小的计算复杂度.     

用时域自相关匹配方法降低OFDM系统的PAPR

对时域自相关匹配方法降低 OFDM (正交频分复用)系统的PAPR (峰均功率比)进行了研究。该方法的基本思想是在时域加入一个随机序列发生器,随机序列与原始信号在时域叠加,以达到降低 OFDM系统 PAPR的目的,并可以在接收端实现信号的盲检测。该方法的信号处理过程是在时域,故仅需要一个 IFFT (快速傅里叶逆变换)操作,就能降低计算复杂度。仿真结果表明,该方法可以获得与传统 SLM (选择性映射)方法相似的PAPR和BER (误码率)性能,但计算复杂度比传统的SLM方法降低了很多,从而验证了该方法的有效性。     

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...     

一种降低MIMO-OFDM系统PAPR的低复杂度SLM算法

为了降低MIMO-OFDM(多输入多输出正交频分复用)系统中传统SLM(选择性映射)算法的计算复杂度,文章提出将原始频域信号分成实部和虚部后分别进行不同的相位旋转,再通过IFFT(快速傅里叶逆变换)调制模块得到相应的时域序列,最后通过多天线间实部和虚部序列的不同组合来产生更多的具有不同PAPR(峰均功率比)的备选序列。仿真结果表明,所提算法能有效地抑制MIMO-OFDM信号的PAPR。相比传统SLM算法能有效降低计算复杂度。     

PAPR Reduction in MIMO-OFDM Systems: Spatial and Temporal Processing

Multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) technology is a promising solution for next generation wireless communications, due to high bandwidth efficiency, resistance to RF interference, and robustness to multipath fading. A major drawback of OFDM is its high peak-to-average power ratio (PAPR) which results in non-linearities in the output signal. In this paper, two methods based on spatial/temporal processing are proposed to reduce the PAPR of MIMO-OFDM systems. These methods divide the OFDM block at each transmit antenna into some subblocks. Then, spatial and temporal processing in the form of circular shifting or interleaving are applied to generate different candidate sequences. Finally, for each transmit antenna the candidate sequence with the lowest PAPR is chosen for transmission. Compared to the conventional PAPR reduction schemes such as ordinary partial transmit sequences (O-PTS), the proposed methods require lower computational complexity and have superior PAPR reduction performance.     

Constrained Message Length Coding for Low Peak to Average Power Ratio in FBMC: OQAM Systems

The FBMC generation techniques are found to surmount the disadvantages of the IFFT/FFT based OFDM system. The minimization of PAPR is a much sought after solution by all multi-carrier methods. This paper investigates the possibility of a unified approach for error control coding and PAPR minimization in an FBMC-OQAM system. A new coding procedure called Constrained Message Length (CML) coding is presented in this paper. A new perspective on PAPR and an analytical framework for estimating the PAPR is also presented. Hybrid techniques using coding and companding are tested for different channel models, and their BER performance is on par with the BCH system. The proposed system is of low complexity and has a PAPR of only 3.81 dB, which is better than or comparable with the existing systems that are using complex methods. This paper has uniquely investigated the dependence of PAPR on the input data variation for a different set of random data loads. The CML coding proposed here can minimize the input data dependent PAPR deviation to a low variance of 0.045 dB, which provides an increased linear region of operation to the power amplifier in the RF section.

     

Adaptive PAPR Reduction Scheme for OFDM Using SLM with the Fusion of Proposed Clipping and Filtering Technique in Order to Diminish PAPR and Signal Distortion

One of the main disadvantages of multicarrier transmission is the high peak-to-average power ratio (PAPR) of the transmitted signal. If the highest transmitted power is confined by the application restrictions or regulatory, the result is to decrease the average power permitted under multicarrier transmission. Selected mapping (SLM) is a standard PAPR reduction scheme that is appropriate for orthogonal frequency division multiplexing (OFDM) scheme as it realizes the performance of PAPR reduction without signal distortion. This paper proposes a method in order to handle the difficulties of high PAPR in OFDM scheme. The offered system is an arrangement of two distinguished methods, such as clipping and SLM. Compared to other hybrid methods, where the individual methods are implemented sequentially, this paper integrates the clipping method in the SLM procedure. This produces a supplementary PAPR reduction associated to the serial arrangement. Simulation results specify that the offered scheme acquires the performance of appropriate PAPR reduction with low computational complexity. The PAPR reduction at different number of subcarriers is analyzed and compared with the existing research work. The performance of relative energy efficiency has also been focused on this paper.

     

An Overview: Peak-to-Average Power Ratio Reduction Techniques for OFDM Signals

One of the challenging issues for Orthogonal Frequency Division Multiplexing (OFDM) system is its high Peak-to-Average Power Ratio (PAPR). In this paper, we review and analysis different OFDM PAPR reduction techniques, based on computational complexity, bandwidth expansion, spectral spillage and performance. We also discuss some methods of PAPR reduction for multiuser OFDM broadband communication systems.     

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。      

Peak to Average Power Ratio Reduction in ECMA-368 Ultra wideband Communication Systems Using Active Constellation Extension

Multiband Orthogonal Frequency Division Multiplexing (MB-OFDM) is an efficient approach for The ECMA-368 Ultra Wideband (UWB) wireless communication Standard. However, the high Peak to Average Power Ratio (PAPR) of MB-OFDM UWB signals, limits the power efficiency of the High Power Amplifier (HPA) due to nonlinear distortion. Hence the need to reduce the PAPR of MB-OFDM UWB signals. In this paper, the efficiency of some recently proposed methods including the Active Constellation Extension Approximate Gradient-Project technique (ACE-AGP) is evaluated in real ECMA-368 communication system, with the use of typical HPA models and the UWB channel models defined in IEEE 802.15.3a standard. The PAPR measure and the bit error rate (BER) are used as performance measures in this evaluation.The results indicate that the ACE-AGP algorithm introduces a significant reduction of PAPR about 6.7 dB and reduces the BER degradation in all UWB channel models with different data rates.     

一种降低OFDM信号PAPR的新方法

正交频分复用(OFDM)技术的一个缺点是信号的高峰值平均功率比(PAPR)大大降低了系统中线性功放的效率。本文提出一种新的基于Nyquist脉冲成形的PAPR抑制方法。这种方法基于选择适当的Nyquist脉冲波形集合对OFDM的各个子载波进行脉冲成形。分析论证了该方法的PAPR上限值和所用的脉冲成形波形集合。仿真结果表明该方法能有效降低任意子载波数目的OFDM信号的PAPR值,而且与已有方法相比应用更为简单。因此脉冲成形技术不仅能对传输信号进行频谱成形来提高系统的频带利用率,而且还可以减小信号的PAPR值。     

基于OFDM的POF通信PAPR抑制研究

在基于OFDM调制技术的塑料光纤通信系统中,发送信号的峰值平均功率比（PAPR）过高将会影响到系统的通信质量。通过比较已有的几种降低OFDM信号PAPR值的方法,文中提出了一种冲激整形技术方法,对输入的数据进行线性变换,改变了原始数据相位和幅度的分布,降低PAPR值,并给出了如何使用改进的奈奎斯特脉冲来调制各个子载波的时域脉冲波形。仿真结果表明：该方法计算复杂度低,运行效率高,并能够有效降低OFDM信号的PAPR值。     

MIMO—OFDM系统中降低峰均功率比技术的研究

多输入多输出正交频分复用（MIMO-OFDM）系统已成为第四代无线通信的关键技术之一，而系统所产生的高峰均功率比（PAPR）信号是限制MIMO-OFDM技术实用化的主要障碍。针对此，对MIMO-OFDM系统中现有的几种降低PAPR的传统及改进算法进行了详细介绍，并描述了改进算法相对于传统算法的主要优点。     

太赫兹频段OFDM一体化波形的雷达探测性能分析

传统的正交频分复用(OFDM)信号在太赫兹通信系统中通常会面临峰均功率比(PAPR)过高的问题,严重降低功率放大器的效率,恶化太赫兹链路的非线性效应。恒模雷达-通信一体化波形可以抑制PAPR的影响。本文采用模糊函数作为评价标准,从距离和速度两方面分析和比较了太赫兹频段正交频分复用-16阶正交幅相调制-线调频(OFDM-16QAM-LFM)、正交频分复用-二进制相移键控-线调频(OFDM-BPSK-LFM)、正交频分复用-最小相移键控-线调频(OFDM-MSK-LFM)3种OFDM一体化波形的雷达探测性能。数值仿真结果表明,OFDM-16QAM-LFM波形在太赫兹频段的距离和速度探测性能良好,但PAPR过高;OFDM-BPSK-LFM、OFDM-MSK-LFM波形采用相位调制代替幅度-相位调制,保持恒定包络特性;OFDM-BPSK-LFM一体化波形的距离分辨力不会随着子载波数量增加而恶化,但速度分辨力随着子载波数量的增加而受到很大影响,不适宜用于高速运动状态下多目标的速度检测;OFDM-MSK-LFM波形可承载更多的子载波,适应复杂场景下的多载波雷达探测需求。本文方法为不同应用场景的一体化波形选择提供了参考。