OFDM与MIMO-OFDM系统中PAPR问题研究

正交频分复用(OFDM)和MIMO-OFDM技术都存在高峰均比的问题,大多数方法都是把降低OFDM峰均比的方法直接使用MIMO-OFDM系统,但在与MIMO-OFDM系统的匹配上存在较大问题。分析了OFDM和MIMO-OFDM的系统模型及PAPR,从理论上分析了OFDM和MIMO-OFDM两系统的关系,给出了在MIMO-OFDM系统中降低PAPR需要注意的问题,为OFDM和MIMO-OFDM系统的技术实用化做好理论基础。     

OFDM系统中基于非均匀量化的PAPR抑制方法

对利用非均匀量化技术来降低OFDM系统的PAPR值的方法进行了理论分析,并且将这一方法与实际的无线局域网IEEE802.11a系统进行了仿真。提出了在保证系统性能指标的前提下通过确定非均匀量化最优参数来最大程度降低PAPR值的方法。     

OFDM技术及其PAPR降低算法仿真分析

介绍了OFDM技术的发展现状及应用前景.针对OFDM系统峰均比较高的缺点,研究降低PAPR的各种算法,分析与比较不同算法的优势与不足,并对降低峰均比的压扩变换法、PTS算法以及SLM算法进行了计算机仿真,同时给出不同算法下的系统误码率性能仿真结果,指出扰码类算法在降低PAPR方面的优势.仿真结果对PAPR问题的研究具有借鉴意义.     

限幅SLM算法降低DD-OFDM系统PAPR的研究

提出了限幅SLM(Selected Mapping)算法降低直接检测光正交频分复用系统(DD-OFDM)的峰均功率比(peak-to-average power ratio,PAPR).SLM算法降低了PAPR出现的概率,但并不能完全限制高PAPR.限幅SLM算法在传统SLM算法基础上对高PAPR信号进行限幅运算,进而将PAPR控制在所需要的范围内,相对限幅算法又改善了系统误码率性能.该算法可以控制高PAPR,进而降低光信号的功率,其有效性在DD-OFDM系统信道仿真中得到证实.     

一种基于SLM的抑制PAPR的改进算法研究

正交频分复用(OFDM)作为一种特殊的多载波传输(MCM)方案,具有较高的频带利用率和良好的抗多径干扰能力。但较高的峰均功率比(PAPR)是限制其应用的一个主要缺点。选择性映射(SLM)算法是无失真降低OFDM系统PAPR的有效方法,但其复杂度较高。因此提出了一种基于SLM的抑制PAPR的改进算法。仿真结果表明,该方法即有效地降低了SLM实现的复杂度,又大幅降低了PAPR,提高了OFDM系统性能。     

存在非线性失真和相位噪声影响的CP-OFDM与 TDS-OFDM数字电视地面广播传输系统的性能分析

本文概述了数字电视地面广播传输系统中存在的非线性失真和相位噪声影响因素;用模型统一表达了CP-OFDM和TDS-OFDM的OFDM复包络信号;从理论上分析了循环前缀和不断插入的导频训练序列会导致基于CP-OFDM的数字电视地面广播传输系统比在同等的外界条件下的基于TDS-OFDM的数字电视地面广播传输系统具有更低的有效数据符号信噪比水平;详细推导了在非线性失真和相位噪声共同影响下的CP-OFDM系统和TDS-OFDM系统的有效数据符号的统一信噪比表达式;定义并统一表达了在非线性失真和相位噪声共同影响下的CP-OFDM系统和TDS-OFDM系统的性能恶化指标;从理论和计算机仿真两方面比较分析了受到各种不同非线性失真和相位噪声影响的基于CP-OFDM和基于TDS-OFDM的两种不同数字电视地面广播传输系统的性能恶化程度.     

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.     

降低光正交频分复用系统PAPR的算法研究

本文针对光正交频分复用(O-OFDM)系统的高峰均比(PAPR)问题,提出了联合降低PAPR算法,利用选择映射法随机改变OFDM码元的初始相位分布,降低码元峰值出现的概率,采纳限幅加窗方法降低码元峰值,从而达到降低系统的PAPR。仿真结果表明,联合降低PAPR算法有效降低了O-OFDM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.     

Definition of efficient PAPR in OFDM

A high PAPR is a main drawback of OFDM. There are many methods for reducing the PAPR with an ultimate goal of reducing the PAPR as much as possible. It is shown that if, among other factors, the power efficiency-PAPR relationship of the power amplifier is also taken into account, then there exists a PAPR level for which the BER reaches a minimal value. This PAPR may be used as a definition of an efficient PAPR. The efficient PAPR is not necessary the lowest possible value of PAPR.     

A Robust Peak-to-Average Power Ratio Reduction Scheme by Inserting Dummy Signals with Enhanced Partial Transmit Sequence in OFDM Systems

Peak-to-average power ratio (PAPR) is one of the main drawbacks in orthogonal frequency division multiplexing (OFDM) systems. High PAPR forces the power amplifier to back off in order to operate in its linear region, which degrades the power efficiency of the system. Several PAPR reduction techniques have been developed, but most of them have not considered both complexity and PAPR reduction. In this paper, a novel PAPR reduction scheme based on the insertion of dummy sequences to an enhanced partial transmit sequence is proposed. By applying this scheme the PAPR performance is enhanced compared to the conventional methods while the complexity is significantly reduced. Numerical analysis is carried out with OFDM signal and QPSK modulation.     

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...     

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.     

TDS-OFDM系统的功率调整技术研究

针对频域双PN序列填充的TDS-OFDM系统,提出了通过调整训练序列与帧体数据功率比值来降低系统误符号率的方法,并通过调整两者的功率比值对系统在多径衰落信道下的误符号率性能进行仿真.仿真结果表明选择合适的功率比值会带来信噪比的增益.     

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.

     

Unitary peak power reduction in multiple transmit antennas

This paper proposes a new peak-to-average power ratio (PAPR) reduction scheme in multiple transmit antenna environments. Instead of applying individual PAPR reduction on each antenna, a joint PAPR reduction technique is proposed. By applying a relevant unitary rotation over the transmit antennas, overall PAPR of the multiple transmit antenna system is reduced. This scheme does not require any side information to decode the signal in the receiver, enabling throughput-lossless PAPR reduction. Furthermore, there is no increase in the complexity of the receiver.     

TDS-OFDM系统中PN序列的研究

文中介绍了数字电视地面广播传输系统中的TDS-OFDM技术，阐述了PN序列在TDS-OFDM系统中可以作为OFDM块的保护间隔，还可以被用作系统同步和信道估计等。仿真结果表明，TDS-OFDM系统在多径条件下具有满意的性能。     

A ZCMT Precoding Based Multicarrier OFDM System to Minimize the High PAPR

This paper presents a Zadoff-Chu matrix transform (ZCMT) precoding based multicarrier orthogonal-frequency-division-multiplexing (OFDM) system to minimize the high peak-to-average power ratio (PAPR). In the proposed system, ZCMT kernel is applied to the constellation symbols which not only reduces PAPR but also improves bit-error-rate (BER) performance. The ZCMT precoded OFDM signals allow the radio-frequency high-power-amplifier (HPA) to operate near its saturation level, thus maximize the power efficiency. Extensive computer simulations have been performed to analyze the PAPR, BER and power-spectral-density (PSD). Simulation results show that the proposed system has excellent PAPR gain and BER performance with no spectral distortion.