应用PTS降低MIMO-OFDM信号峰均比技术研究

多输入多输出正交频分复用（MIMO—OFDM）系统已成为新一代高速通信系统研究中的热点。而系统所产生的高峰均比（PAPR）信号是限制MIMO—OFDM技术实用化的主要障碍。在对部分传输序列（PTS）技术进行研究的基础上。本文提出了一种应用PTS降低MIMO—OFDM信号峰均比（PAPR）的方案一并行PTS。仿真结果表明。该方法能有效降低MIMO—OFDM信号峰均比。     

基于频域导频PTS-OFDM系统峰平比降低技术

对于无线通信系统而言,OFDM是一种非常有吸引力的传输技术,但是OFDM信号具有较高的峰平比特性.为了减小信号峰平比,本文利用部分传输序列PTS技术,提出了一种适用于基于频域导频OFDM系统的峰平比降低实现方案,给出了其实现算法及系统控制策略;并利用计算机仿真对该系统的峰平比和误码率性能进行了分析,仿真结果表明:PTS技术可以有效地改善OFDM信号的高峰平比特性.本方案采用FPGA实现其相应的硬件电路,经过实际的OFDM系统样机传输测试,证明了所提方法的实用性及其良好的性能.     

PTS与限幅结合降低OFDM峰均比的改进算法

提出了一种基于部分传输序列(PTS)算法和限幅算法相结合的改进算法来降低正交频分复用(OFDM)系统的峰均功率比(PAPR).该算法先利用PTS算法对OFDM信号进行处理从而选择出限幅噪声最小的一路OFDM信号,所得OFDM信号再利用限幅法进行处理.因此可有效改善OFDM信号经过限幅引起的限幅噪声,减小限幅对OFDM系统的影响.数据仿真验证了所提方法的有效性.     

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。     

一种基于部分传输序列降OFDM系统高峰均比的改进方法

如何降低正交频分复用系统（OFDM）中的峰均功率比是有效应用OFDM技术的关键。本文基于部分传输序列（PTS），并针对部分传输序列过于繁重的计算量。提出了一种运用各采样点组相位相量信息的改进算法。新算法以较少的冗余度获得了比部分传输序列最优和方法更好的性能，减少了系统的计算复杂度。仿真结果表明新算法更好的降低了OFDM系统信号的峰均比。     

降低PTS方法复杂度的原理及应用

传统的降低OFDM信号峰均比值的部分传输序列(PTS)方法需计算全部相位旋转因子序列所对应的峰均比值,因而计算复杂度很大.该文分析了OFDM信号峰值出现的规律,提出了搜索合乎需求的相位旋转因子序列的一般性原则,并在此基础上提出了一种全新的降低PTS方法复杂度的方案.理论分析和仿真结果表明,该方法在大幅降低系统复杂度的同时,性能损失较少.     

基于多层循环搜索的部分传输序列算法

高峰均功率比是OFDM(Orthogonal Frequency Division Multiplexing)信号的主要缺点之一,峰均比过高会加重OFDM系统的非线性失真.部分传输序列算法(Partial Transmit Sequences,PTS)是有效降低OFDM信号峰均功率比的传统算法.该算法由于采用穷尽式搜索方式搜索最优相位因子组合,因此具有较高的计算复杂度,并且随着子数据块分组数的增加部分传输序列算法计算量呈指数形式上升,很难在实际的通信系统中得到应用.本文提出了一种具有较低计算复杂度的多层循环部分传输序列算法( Multi-Loop PTS),该算法通过对相位因子进行多层循环计算比较,舍去了部分冗余计算,且避免了相位因子搜索陷入局部最优点,在保证算法性能的同时降低了算法复杂度.并且通过仿真分析证明了本文提出的MLPTS算法能够较好的权衡PAPR性能和计算复杂度之间的关系.     

OFDM系统中降低峰均功率比算法的研究

正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)系统中,峰均功率比(Peak to AveragePower Ratio,PAPR)过高会导致收发器的非线性失真,严重影响系统的性能。传统的部分传输序列(Partial TransmitSequence,PTS)算法能够有效地降低PAPR,然而其计算复杂度随着分块数目增长呈指数增加。在研究PTS的基础上提出了双重迭代PTS算法,该算法利用增加迭代次数,并且每次迭代时选择不同的相位旋转因子集合来优化OFDM系统的峰均比性能。该算法在峰均比性能上优于常规OFDM系统以及普通迭代PTS算法,在降低峰均比性能和计算复杂度之间取得了较好的折衷。     

一种降低OFDM信号PAPR的改进PTS方法

正交频分复用(OFDM)系统的一个主要缺点是信号的峰值功率与平均功率比(PAPR)很高。本文研究了利用信号扰码技术降低OFDM系统峰均比的一种典型算法:部分传输序列法(PTS),提出了一种将随机分割方法、交织分割方法与迭代移位搜索加权因子相结合的改进PTS算法。仿真结果表明,改进后的算法在改善PAPR性能和计算的复杂度之间取得了较好的折衷。     

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.     

GA-PTS Using Novel Mapping Scheme for PAPR Reduction of OFDM Signals Without SI

In recent time orthogonal frequency division multiplexing (OFDM) has proved its mettle as a preferred choice for high speed transmission in wireless applications due its efficient mechanism to combat the inter symbol interference. However sudden high peaks in OFDM signal envelope lead to high peak to average power ratio (PAPR). Enhanced values of PAPR result into complex RF amplifier circuit with reduced efficiency. There are various methods available for PAPR reduction, out of them partial transmit sequence (PTS) is most effective proven choice for PAPR reduction. However PTS technique requires cumbersome searching of all possible phase factors to find optimal phase factor which produces lowest PAPR, the information regarding optimal phase set used at the transmitter need to be sent to the receiver as side information (SI) for decoding purpose, however transmitting SI requires additional transmission bandwidth thus reducing overall bandwidth efficiency. To reduce the exhaustive searching genetic algorithm (GA) could be used with PTS leading to GA-PTS system. In this paper a GA-PTS system is proposed which uses novel octagonal geometry for constellation extension purpose. This scheme does not require transmission of any side information for decoding purpose at receiver and at the same time GA-PTS system reduces the required number of searches. Simulations are presented to show that proposed scheme provides similar PAPR performance as conventional PTS but without need of SI transmission at reduced number of searches.     

一种改进的PTS算法降低OFDM峰均比研究

部分传输序列(PTS)算法能够有效地降低OFDM通信系统的平均峰值功率比(PA-PR)。文中研究了哈达码矩阵及传统的μ率压缩算法,提出了一种新的能够有效的降低PAPR算法。提出的算法是基于传统的PTS算法,利用哈达码矩阵优化部分传输序列,结合μ率压缩算法进而降低OFDM系统的PAPR值。通过实验仿真证明,文中提出的算法能够降低OFDM系统的PAPR值,而且性能更加优越于单独的μ率压缩以及传统的PTS算法,具有良好的峰值平均功率比性能。     

OFDM系统降低峰均功率比的研究

正交频分复用技术非常适合高速通信系统,但却存在着高峰均比问题。部分传输序列法因其灵活有效的降低OFDM系统的峰均功率比而被广泛的研究。对以前技术研究之后,提出一种基于相位的搜索算法。仿真结果表明,用这种方法降低系统的计算复杂度,并且其性能和以前的方法相比没有降低。     

Joint ICI Cancellation and PAPR Reduction in OFDM Systems Without Side Information

Intercarrier interference (ICI) self-cancellation, new ICI self-cancellation and conjugate cancellation schemes have been proposed in the literature to mitigate the effect of ICI. In this paper we have performed the mathematical analysis of PAPR performances for ICI self-cancellation, new ICI self-cancellation and ICI conjugate cancellation schemes and it is found that PAPR performance of these schemes are either very close to or poorer than the standard OFDM signal, which necessitates the requirement of PAPR reduction. After realizing the need of PAPR reduction in ICI cancellation schemes, we have proposed a joint scheme to reduce ICI and PAPR simultaneously. In this paper, we have proposed a multipoint partial transmit sequence (PTS) scheme, to improve the PAPR performance of ICI cancellation schemes. The proposed multipoint PTS based PAPR reduction scheme is coupled with ICI cancellation schemes in such a way that CIR performance of these schemes after coupling remains unchanged and no SI is required at the receiver to recover the original data signal. A comparison of CIR and PAPR performances for ICI cancellation schemes with and without PAPR reduction is also presented in this paper. The analytical results of CIR and PAPR performances for conventional ICI cancellation and joint ICI cancellation and PAPR reduction confirm the outperformance of the proposed scheme. We have also evaluated the SER performance of the joint schemes over additive white Gaussian noise and fading channels and presented a comparison with other existing schemes.     

PTS with Non-Uniform Phase Factors for PAPR Reduction in OFDM Systems

Partial transmit sequence (PTS) is one of the effective and uncomplicated PAPR reduction methods for OFDM systems. The phase factors applied in the weighting sequences are assumed to be uniformly distributed within [0, 2pi). By carefully investigating the phase distribution of OFDM signals, we proposed a modified PTS scheme outperforming the conventional PTS scheme in PAPR reduction performance. The process of the proposed scheme is the same as the conventional PTS, except for applying the new non-uniform phase factors. The required side information is the same as the conventional PTS applying uniform phase factors.     

Selected-Mapping Peak-to-Average Power Reduction Method with Orthogonal Pilot Sequences in Underwater Acoustic OFDM System Without Side Information

A novel Selected-mapping (SLM) Peak-to-average power ratio (PAPR) reduction scheme requires no Side information (SI) in Underwater acoustic (UWA) OFDM system is proposed. In the proposed scheme, every distinct phase sequence is represented by a unique Orthogonal comb pilot sequence (OPS), and the orthogonal properties of the OPSs are used to distinguish the index of phase sequences at the receiver. Therefore, the proposed scheme does not need to reserve bits for transmitting SI, so that the data rate can be raised. Simulation results show that the PAPR reduction performance has almost 0.5dB gains comparing to the Conventional SLM (C-SLM) scheme and the Bit error ratio (BER) performance is approximately the same as the SLM scheme with perfect SI. Field experimental results also demonstrate that the proposed scheme can differentiate phase sequences, therefore significantly enhance the quality of the UWA OFDM communication system.     

一种简单PTS旋转因子优选方法降低OFDM数字广播系统的PAPR

OFDM技术已经广泛应用于数字广播系统，首先对OFDM技术中用PAPR（peak-to-average power ratio）的基本定义和PTS方法作简要的介绍，之后提出一种简单的PTS旋转因子优选方法来降低以朋，仿真表明，提出的方法能够有效地降低OFDM系统的PAPR，运算复杂度与基本PTS相当。     

一种简单PTS旋转因子优选方法降低OFDM数字广播系统的PAPR

OFDM技术已经广泛应用于数字广播系统,首先对OFDM技术中PAPR(PEAK-TO-AVERAGE POWERRATIO)的基本定义和PTS方法作简要的介绍,之后提出一种简单的PTS旋转因子优选方法来降低PAPR,仿真表明,提出的方法能够有效地降低OFDM系统的PAPR,运算复杂度与基本PTS相当。