DVB-C接收机中均衡的一种实现方法

针对DVB-C信号的特点,接收机中自适应均衡器采用的是分数间隔判决反馈均衡器的结构,与改进的CMA盲均衡算法和自适应算法DDLMS相结合.在仿真中,在有线多径信道条件下,此均衡器能较好地消除多径干扰,具有较好的性能,而不需要任何的训练序列和导频的存在.     

TCM数据传输系统的自适应均衡

介绍两种要吧有效地用于财制（ＴＣＭ）数据传自应均衡技术，即交织判决反馈均衡（ＩＤＦＥ）和降态序列估值（ＲＳＳＥ）。最后对它们的性能进行了评价。     

一种FMT系统内的MMSE-DFE均衡方法及其性能研究

介绍了滤波多音调制(FMT)系统的基本原理,分析了FMT系统内码间干扰的形成原因,提出了在每子信道上采用最小均方误差判决反馈(MMSE-DFE)均衡方法来消除系统的码间干扰的方法。论文给出了MMSE-DFE结构的时域均衡实现方法,研究了最小均方误差判决反馈均衡在FMT系统内的均衡性能,给出了理论和仿真结果。     

一种实现高性能TCM的卷积编码器结构

本文提出了一种用于网格编码调制(TCM)技术的卷积编码器结构,并在三种不同的信号分配约束条件下对具有最大自由欧几里德距离的TCM码进行了搜索,结果表明:当状态数目较少时,Ungerboeck建议的规则是获得好码的前提条件,当状态增多时,可能存在有其它的信号分配形式达到最好的性能。     

单载波频域均衡系统中一种简化的IBDFE算法

在单载波频域均衡系统中,线性均衡算法虽然简单易行,但是其抑制噪声干扰和符号间干扰的能力有限,因此需要引入非线性的反馈和迭代机制以进一步提升系统性能.迭代块判决反馈均衡（Iterative Block Decision Feedback Equalization,IBDFE）就是一种行之有效的非线性算法,但其缺点是计算复杂度高.鉴于此,在IBDFE结构的基础上,利用最小均方误差准则,推导出了一种新的简化算法.之后,对简化后算法和现有低复杂度算法的均方误差（Mean Square Error,MSE）性能进行了理论分析和比较,并在两种无线多径衰落信道下对三种不同的算法进行了仿真.结果表明,在所给信道条件下,这种算法在迭代两次后已基本收敛.同时,仿真也验证了MSE分析的结论.最后,对算法复杂度的分析和比较表明,提出的简化算法相比传统IBDFE算法,其误比特率性能有所下降,但能有效地减小计算量.     

一种用于水声相干通信系统的自适应均衡算法

多通道判决反馈均衡器(MC-DFE)是水声相干通信克服信道多径效应、消除码间干扰(ISI)的主要手段。为了减少多通道数据处理的复杂性、优化算法、提高算法精度,该文提出了自适应自最优预合并多通道判决反馈均衡算法。该算法将快速自优化LMS分集合并(FOLMSDC)算法、快速自优化LMS(FOLMS)算法和快速自优化LMS相位补偿(FOLMSPC)算法有机地结合在一起,使用统一的误差信号,按照最小化均方误差(MMSE)准则调节各部分的系数,从而实现均衡器性能的全局最优。仿真试验和湖上试验对该算法的性能进行了分析。实验结果表明,该文提出的算法可以进一步减少运算量,提高通信系统的接收性能,算法性能优于已有算法。     

一种用于水声相干通信系统的自适应均衡算法

多通道判决反馈均衡器（MC—DFE）是水声相干通信克服信道多径效应、消除码间干扰（ISI）的主要手段。为了减少多通道数据处理的复杂性、优化算法、提高算法精度,该文提出了自适应自最优预合并多通道判决反馈均衡算法。该算法将快速自优化LMS分集合并（FOLMSDC）算法、快速自优化LMS（FOLMS）算法和快速自优化LMS相位补偿（FOLMSPC）算法有机地结合在一起,使用统一的误差信号,按照最小化均方误差（MMSE）准则调节各部分的系数,从而实现均衡器性能的全局最优。仿真试验和湖上试验对该算法的性能进行了分析。实验结果表明,该文提出的算法可以进一步减少运算量,提高通信系统的接收性能,算法性能优于已有算法。     

室内可见光通信中的线性均衡与判决反馈均衡

信道均衡是光通信的关键技术之一。信道均衡能有效地克服信息传输中的多径干扰和消除码间串扰,适合于数据传输。本文针对室内可见光通信系统中由信道失真引起的严重的码间串扰（ISI）情况,研究迫零均衡（ZFE）、最小均方误差（MMSE）均衡、判决反馈均衡（DFE）3种均衡技术,并利用计算机仿真对3种均衡技术的性能进行评估。仿真结果表明,判决反馈均衡器具有明显的优越性。     

用判决反馈均衡器实现判决导引代价函数的盲均衡算法

用判决反馈均衡器实现判决导引代价函数的盲均衡算法ＴｈｅＢｌｉｎｄＥｑｕａｌｉｚａｔｉｏｎｏｆＤｅｃｉｓｉｏｎ－ＤｉｒｅｃｔｅｄＣｏｓｔＦｕｎｃｔｉｏｎｂｙＤｅｃｉｓｉｏｎＦｅｅｄｂａｃｋＥｑｕａｌｉｚｅｒ￥ＹａｎｇＣｏｎｇｈｕｉ（ＳｈｏｕＧａｎｇＩｎ...     

一种基于盲均衡的新均衡器算法及实现

基于简化星座图(RCA)的盲均衡算法提出了一种新的均衡器算法———RCA-LMS算法,有效地结合了RCA算法和传统的最小均方(LMS)算法的优点,并应用于选择性反馈均衡器(selective feedback equalizer,SFE)结构,实现了RCA-LMS选择性反馈均衡器(RCA-LMSSFE)。仿真结果表明,该均衡器在低信噪比条件下,能较快地收敛,有较小的稳态剩余误差,从而有效地减小了信号的码间干扰,提高了通信系统的抗干扰能力。     

网格编码调制在卫星高速数据传输中的应用

首先对网格编码调制(Trellis Coded Modulation,TCM)进行了系统概述,重点讨论了网格编码调制技术的基本特点、集合分割映射原理及Viterbi译码算法,并对TCM在AWGN信道中的性能进行了仿真,由此论证了网格编码调制技术在功率和带宽受限的卫星高速数据传输中的应用。     

一种自适应语音增强均衡器的研究

在参考滤波器组的基础上，提出一个用于语音和音频信号进行时不变或自适应谱修正的数字滤波器结构，主要用于音频信号均衡和降噪。在频域计算滤波器系数的同时，信号在时域滤波。与通常频域处理相比，在信号延迟、原型滤波器设计、复杂性等方面，该结构有良好的特性。该算法既适用于均匀频率分辨率，也适用于非均匀频率分辨率。     

基于非编码信息匹配的自适应Turbo TCM编码调制方案

本文提出了一种通过调整非编码信息量,并与信号映射相结合来改变编码、调制模式的自适应Turbo TCM编码调制方案,称之为基于非编码信息匹配的自适应Turbo TCM编码调制方案.由于将Turbo码和TCM编码调制技术相结合得到的Turbo TCM编码调制方案的带宽效率高,所以,在慢时变无线衰落信道中,自适应Turbo TCM编码调制的平均频谱效率也将很高.给出了该方案的工作原理、设计方法,并通过蒙特卡洛(Monte Carlo)仿真研究了该方案的性能.与现有编码调制方案相比,该方案具有频谱效率高、易于设计和实现的优点.     

A NEW ADAPTIVE EQUALIZER STRUCTURE FOR NONLINEAR CHANNELS

Based on the analysis of nonlinear channel models,a new connectionist model ofadaptive equalizer is constructed.Comparing with the connectionist model using the Volterraseries to extend the input vector space,the number of weights with the new structure is reducedsignificantly.It is shown by simulations that the weight values of the new scheme converge to theoptimal values closely for non-minimum phase channels as well minimum phase channels,if thechannel noise is small enough.Testing results of the BER(Bit Error Rate)tell us that the newadaptive equalizer for nonlinear channels is superior to the conventional linear equalizers in theequalization performances.     

一种短延时Turbo编码调制系统的设计

本文设计了一种比传统体制减少了一半延时的Turbo编码调制系统,介绍了交织器的相关限制.提出了一种在译码过程中对信道值的估计方法,使得外信息的计算更加趋于精确,从而提高了译码性能.这种迭代译码算法是标准格码调制译码算法的一种自然推广,同时也类似于二元Turbo码在BPSK调制下的逐比特译码算法.采用吞吐率为2bits/s/Hz的8PSK调制,比特错误率为10^-5所需的信噪比与Shannon限相距不到0.4dB.     

An efficient decision feedback equalizer for the ATSC DTV receiver

In this paper an efficient decision feedback equalizer is presented for the equalization of the received signal in the eight level vestigial sideband, Advanced Television Systems Committee, digital television system, adopting a novel detection rule for symbol detection at the output of the equalizer. The conventional hard limiter is replaced by an efficient symbol detection algorithm, based on the underlying trellis coded modulated coding of the transmitted symbols. The proposed decision device has a marginal computational cost and it can be implemented using simple combinatorial and sequential logic circuitry. When the equalizer operates in the decision directed mode, the normalized least mean squared algorithm is utilized for the adaptation of the equalizer coefficients, in a “stop-and-go” like mode, triggered by a reliability signal associated to the detected symbols. The performance of the proposed method is illustrated by typical computer simulation.     

A MATRIX ALGORITHM FOR COMPUTING THE FREE SPACE DISTANCE OF TCM SIGNAL SEQUENCES

In this paper, the problem of computing the free distance of Trellis Coded Modulation (TCM) signal sequence has been discussed; a new algorithm-the matrix algorithm is proposed; and the step-number estimation problem for state transmission to compute the free distance of TCM signal sequence has been theoretically solved. The matrix algorithm is derived from the Viterbi algorithm, and is an implementation of Viterbi algorithm in the form of matrix. Compared with other algorithms, the matrix algorithm gains two advantages: (1) The explicit solution, and its relatively less complexity. (2) More reflexible ability to the signal space distance variation. As examples, the results of some TCM signal sequence on AWGN channel and fading channels have been presented.     

双弹光调制器动态耦合及控制的一种新方法

针对双弹光调制器(PEM)中各调制器本征频率差异 及其随温度变化造成的调制效率降低问题,提出 了基于中心频率控制的解决方案。首先,建立了PEM机械特性等效电路,分析了驱 动电压、驱 动频率和谐振频率的动态耦合关系,确定了大光程差条件下驱动信号加载方法;其次,结合 不同谐振 频率PEM的幅频、相频特性曲线,提出了基于中心频率的双PEM控制方法;最后,采用 数字频率合成(DDS)技术和数字锁相环(DPLL)技术对双PEM进行驱动及谐振频率漂移跟踪,使 各PE M处于同频同相状态。实验结果表明,本文控制方法能够使双PEM调制光程差达 到单个PEM的2倍,达到1080μm。     

Linear precoded wavelet OFDM‐based PLC system with overlap FDE for impulse noise mitigation

In recent years, power lines have gained significant interest for their use in high‐speed communications because of the already deployed power distribution infrastructure. However, to achieve high data rates with reliability in power line communication (PLC), robust signal processing techniques are required to mitigate channel distortion and noise. Orthogonal frequency division multiplexing (OFDM) as a multicarrier modulation technique has been standardized for PLC; however, to further enhance the quality of communication, wavelet OFDM (WOFDM) has been proposed as a suitable choice. In this article, OFDM‐based and WOFDM‐based PLC systems are studied, and overlap frequency domain equalization (OFDE) as a robust and efficient equalization technique is presented. Moreover, to enhance the efficiency of the OFDE, linear precoding (LP) is also suggested for fast Fourier transform and wavelet transform–based filter bank transceivers over the PLC channel. Performance of the proposed LP‐based OFDM‐OFDE and LP‐based WOFDM‐OFDE systems is compared with previously proposed equalization structures in terms of bit error rate, peak‐to‐average power ratio, and computational complexity via computer simulations. Furthermore, the performance of proposed architectures is also compared with classical equalization techniques under impulse noise with different intensities. Results show that not only the proposed LP‐based WOFDM‐OFDE transceiver performs better than the previous equalization models but also the LP‐based OFDM‐OFDE at the expense of slight increment in computational complexity.