降低OFDM系统峰均比的选择性映射算法研究

正交频分复用(OFDM)是一种具有极高的频谱利用率和抗多径衰落性能良好的多载波调制方式,但是它存在高的峰值功率平均比(PAPR)问题.本文分析了解决该问题的基本选择性映射算法,并从传送边带信息、传输速率和系统的计算量方面对改进的选择性映射算法进行了研究.仿真结果表明使用单极相位序列的选择性映射算法比普通的选择性映射算法可以有效降低0.5dB左右的PAPR.     

改进PTS算法降低OFDM峰均功率比的研究

部分传输序列 (PTS) 算法能够有效的降低正交频分复用(OFDM)系统的峰值平均功率比(PAPR).提出了一种改进部分传输序列(IPTS)模型,它是基于优化最佳相位因子加权之前的部分传输序列思想降低OFDM系统平均峰值功率比.利用这种模型,提出了一种基于哈达码矩阵优化的部分传输序列算法(H-IPTS).实验仿真表明,H-IPTS算法以低的计算复杂度可以达到或优于传统PTS算法相当的效果,具有良好的峰值平均功率比性能.     

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OFDM的PAPR的PTS算法研究

针对正交频分复用技术峰值平均功率比过高的问题,提出了一种低复杂度的次优化算法。首先研究了降低正交频分复用技术系统峰值平均功率比的部分传输序列算法及其峰值平均功率比的抑制性能,分析了次优化算法性能受限的原因,通过增加一次搜索的相位系数的个数,使得新算法性能接近最优算法,并且具有低的复杂度。最后进行了Matlab仿真实验,通过仿真结果可以发现新算法具有高的抑制峰值平均功率比的性能,且具有低的复杂度。     

一种降低MC—CDMA系统峰均比的联合方法

文章提出了一种基于扩频码和选择性映射联合的方法来降低MC—CDMA系统的峰均比（PAPR）。首先对MC—CDMA系统的峰均比进行了理论推导,然后对选择性映射方法中的相位序列进行改进并选择了合适的扩频码,二者相结合来降低系统的峰均比。最后,在充分考虑系统的硬件资源消耗情况下,合理选取了相位序列的个数。通过性能仿真证明,该方法可以有效的降低系统的峰均比。     

OFDM系统中一种降低峰均比的PTS迭代算法

正交频分复用(OFDM)是一种多载波调制技术,存在峰值平均功率比(PAPR)较高的问题。针对部分发送序列(PTS)算法,提出了一种低计算复杂度的迭代算法。理论分析及仿真结果表明,该算法的性能优于选择性映射(SLM)算法,虽略低于PTS遍布法,但它计算复杂度显著降低。     

一种新的相位序列在选择性映射中的应用

正交频分复用（OFDM）和多载波码分多址（MC-CDMA）被广泛认为是未来4G通信的核心技术。但是,OFDM和MC-CDMA信号的高峰均功率比（PAPR）会引起非线性失真并导致误码率性能恶化,这已成为它们实用化的最大障碍。选择性映射（SLM）是一种能有效地降低系统PAPR方法,其中相位序列的选择直接影响降低PAPR的效果。提出将一种新的伪随机扰码作为选择性映射中的相位序列来降低OFDM和MC-CDMA系统的PAPR,仿真得出这种伪随机扰码序列能有效地降低系统的PAPR,且优于传统Walsh-Hadamard、Golay序列。     

OFDM系统降低峰平比技术的研究

OFDM技术具有较高的频谱利用率和良好的抗多径干扰能力,但是其峰值平均功率比(PARP)较高.现在虽然在抑制性能上有了很大的提高,但仍存在各种各样的缺陷,尤其是计算量和系统复杂度方面.文中研究了利用选择性映射(SLM)技术降低OFDM系统峰平比,并提出利用完全互补码来降低SLM的运算复杂度.     

抑制OFDM系统PAPR的PTS算法改进

部分传输序列（PTS）是一种降低OFDM信号的峰值平均功率比（PAPR）的有效方法。PTS采用是在子序列中添加旋转相位因子[0，21π）。通过对OFDM信号相位分布情况进行研究，本文提出一种改进的PTS方法。改进点在其相位旋转因子的选择上，采用每个子块乘以非均匀分布的旋转因子。     

OFDM系统中降低峰均比的算法研究

正交频分复用（OFDM）系统中峰值平均功率比（PAPR）较高,为了解决这个问题,本文介绍两种算法：选择性映射（SLM）算法和预留子载波（TR）算法,并对两种算法分别使用不同序列时所得到的结果进行分析和对比。     

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。     

Method on PAPR reduction in digital beam-forming

Digital beam-forming technology is one of the key technologies in 5G communication.However,the high peak-to-average power ratio in digital beam-forming would make the power amplifier work in the nonlinear region.Nowadays,the solutions to the high peak-to-average power ratio,such as selected mapping,embedded side information selected mapping have some faults:the complexity is high,and the utilization of the bandwidth is low.A blind selected mapping method to reduce the high peak-to-average power ratio based on MUSIC algorithm was proposed.In this method,the side information was omitted,so the utilization of the bandwidth was improved.Simultaneously,the result of the peak-to-average power ratio reduction and the complexity is much more enhanced.     

Performance of OFDM with modified RA codes and clipping

A technique for reducing the peak-to-average power ratio (PAPR) of orthogonal frequency-division multiplexing symbols is considered. By extending the method of selected mapping, we achieve PAPR reduction and significant bit error rate improvement. A set of distinct sequences are generated from the data using a modified repeat accumulate code. The sequence with the lowest PAPR is selected for transmission. Using iterative decoding at the receiver, the original data is recovered without prior knowledge of which sequence was selected.     

A Low Complexity Selected Mapping Scheme by Use of Time Domain Sequence Superposition Technique for PAPR Reduction in OFDM System

By using the time domain sequence superposition (TDSS) technique, in this paper, we propose a low complexity selected mapping (LC-SLM) scheme for the peak-to-average power ratio (PAPR) reduction of the orthogonal frequency division multiplexing (OFDM) system. Unlike the conventional selected mapping (SLM) scheme which needs several inverse fast Fourier transform (IFFT) operations for an OFDM signal, the proposed scheme requires to implement two IFFT operations only. Thus, it can remarkably reduce the computational complexity. Simulation results show that the proposed scheme can achieve similar PAPR performance as the conventional SLM scheme.      

A novel trellis-shaping design with both peak and average power reduction for OFDM systems

A new trellis shaping design is proposed for reducing the peak-to-average power ratio of the bandlimited orthogonal frequency-division multiplexing (OFDM) signals. The approach is based on recursive minimization of the autocorrelation sidelobes of an OFDM data sequence. A novel metric in conjunction with the Viterbi algorithm is devised. The performance of the trellis shaping depends on signal mapping strategy, and the two types of mapping, referred to as Type-I and Type-II, are proposed. The Type-I mapping has no capability of reducing the average power, but it can achieve a significant reduction of the peak-to-average power ratio. On the other hand, the Type-II mapping is designed to achieve both peak and average power reduction. The bit error probability of the system over an AWGN channel is evaluated based on the simulations, which confirms the effectiveness of the proposed scheme.     

基于准循环LDPC码和SLM法降低PAPR的新方法

由于具有频谱利用率高、抗多径衰落能力强等优点,正交频分复用(OFDM)技术已成为通信领域的研究热点之一。但是OFDM技术中存在的高峰均功率比(PAPR),为其实用化设置了障碍。本文提出利用不规则准循环低密度奇偶校验(QC-LDPC)码作为信道编码技术,联合选择映射(SLM)算法抑制高峰均功率比。其中,不规则QC-LDPC码的生成矩阵由校验矩阵中的子矩阵直接构造得到。相对于传统的选择映射算法,该方法能发挥LDPC码和SLM法的联合优势,同时由于采用基于置信传播(BP)的迭代译码算法,计算复杂度低、译码速度快。仿真结果表明,该联合方法既能有效地改善OFDM信号的PAPR特性,又能保证系统获得可靠的误码率性能,且实现简单。      

用选择性映射法减小OFDM信号的峰均比及其改进方法

在研究用选择性映射降法降低OFDM系统峰均功率比的基础上,提出了用m序列对SLM方法进行改进.仿真结果表明:改进方法能使系统的峰均功率比大大降低;而且由于m序列的特性,改进方法的SLM-OFDM系统的复杂度避免了大量的IFFT运算,降低了系统实现复杂度.     

A novel improved SLM scheme of the PAPR reduction technology in CO-OFDM systems

The higher peak-to-average power ratio (PAPR) is a major shortcoming of coherent optical orthogonal frequency division multiplexing (CO-OFDM) systems. Selective mapping (SLM) technology can effectively reduce the probability of high PAPR, but it has higher computational complexity, and requires additional bandwidth to transmit the side information, which will affect the transmission efficiency of the system. In response to these shortcomings, a novel improved SLM (NI-SLM) scheme with low complexity and without side information is proposed. Simulation results show that the proposed scheme can exponentially reduce the computational complexity, and the bit error rate (BER) performance can greatly approach the original signal. What’s more, it shows the better PAPR reduction performance.     

A Modified SLM Scheme With Low Complexity for PAPR Reduction of OFDM Systems

In this paper, we propose a new peak-to-average power ratio (PAPR) reduction scheme of orthogonal frequency division multiplexing (OFDM) system, called a modified selected mapping (SLM) scheme, which considerably reduces the computational complexity with keeping the similar PAPR reduction performance compared with the conventional SLM scheme. The proposed scheme is analytically and numerically evaluated for the OFDM system specified in the IEEE 802.16 standard. For the OFDM system with 2048 subcarriers, the proposed scheme with 4 binary phase sequences can reduce the complex multiplications by 63.5% with the similar PAPR reduction compared with the SLM scheme with 16 binary phase sequences.