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1.
一种短波信道自适应均衡算法的研究   总被引:1,自引:0,他引:1  
基于逐幸存路径处理(PSP)的思想,研究了一种减少状态序列估计(RSSE)的短波信道自适应均衡算法.该算法首先通过训练序列估计信道的参数,然后利用RLS算法对信道参数和输入数据的估计值同时进行逐幸存路径地更新.数值仿真表明,在短波信道环境下,RSSE-PSP算法在减小计算复杂度的同时最大限度地保持了性能增益,其性能明显优于其他均衡算法.  相似文献   

2.
针对同频重叠信号的单通道盲分离问题,提出了一种自校正频偏和调整幸存路径数目的盲分离算法。针对两路QPSK信号同频重叠的且存在频率漂移等单通道信号盲分离,推导了基于过采样的信道参数估计模型,利用纠错编码的方法降低误码率,利用指数加权递归最小二乘法(RLS)估计信道参数,并利用估计出的信道参数校正频率漂移等带来的频率偏差,通过在逐幸存路径(PSP)算法调整幸存路径数目解决信道参数收敛和计算复杂度之间的矛盾,提高了频率漂移等变化信道下的参数估计性能,并降低了计算量。仿真结果表明,该算法能够较好地实现频偏自校正,弥补频率漂移带来的影响,同时可以大幅度降低计算量。  相似文献   

3.
提出了一种适用于无线时变信道的逐幸存处理均衡器。通过训练序列得到信道参数的初始估计值,此后在Viterbi算法进行网格搜索的过程中,使得每一条幸存路径维持各自的信道参数,并在确定幸存分支后利用历史幸存序列对信道参数值进行更新,实现了信道参数的无时延估计。仿真结果表明,在无线时变信道环境下,逐幸存处理均衡器的性能明显优于其他传统均衡器。  相似文献   

4.
针对GMSK混合信号的单通道盲分离问题进行了研究。由于不能直接采用逐幸存路径处理(PSP)算法对GMSK混合信号进行分离,考虑对GMSK信号作线性近似处理,使得GMSK混合信号适用于PSP算法。该算法通过在符号序列和信道参数组成的联合空间进行最大似然估计,保留最优路径,输出符号对,从而获得分离信号。仿真结果表明,使用PSP算法对GMSK混合信号进行分离的误码率性能略优于粒子滤波算法误码率性能,但复杂度远低于粒子滤波算法。  相似文献   

5.
毕琰  钱良 《信息技术》2013,(7):20-23
提出了一种成对载波多址系统中信息序列和信道联合估计的算法。该算法在不具备任一协作通信方发送的信息序列的先验知识前提下从混合信号中解调出两路信息序列。该算法结合了逐幸存路径处理法无延迟的信道参数估计特性和Kalman滤波良好的估计性能。仿真实验表明,该算法具有良好的信道捕获与跟踪能力,且实现较好的符号序列估计性能。  相似文献   

6.
付铁连  于全 《信号处理》2006,22(5):683-685
本文提出了一种衰落信道下OFDM信号的半盲检测算法。采用文献[1]为时变OFDM信道建立的2维非线性递归模型,本文利用稀疏的导频符号估计信道响应,并运用最短路径搜索原理寻找原始的发送序列。计算机仿真结果证明,该算法对OFDM信号进行了快速、准确的半盲检测。  相似文献   

7.
王建明  赵春明 《电子学报》2003,31(3):386-389
在传统的二维RAKE接收机中,通常使用导频信道来估计信道矢量,进而求取加权系数,用于业务信道符号序列的检测.当导频功率较低时,信道估计误差较大,系统性能较差.本文提出了一种新的算法,先利用导频进行信道矢量的初始估计,然后用带投影的迭代最小二乘法,进行信道和符号序列的联合估计,该算法具有计算复杂度低,收敛速度快的特点.仿真结果表明:与传统二维RAKE接收机相比,该算法使系统的误码性能得到了有效改善.  相似文献   

8.
依据最小均方误差准则提出了基于多相正交序列循环移位和基于重复相位旋转Chu两种训练序列设计方法,并给出了相应的最小二乘(RLS)自适应信道估计算法。首先用简单的LS算法对信道进行初步估计,然后采用RLS算法进行自适应滤波器提高信道估计的性能,最后,将滤波后得到的时域信道估计经过FFT变换为频域信道响应,并对OFDM数据符号进行频域均衡。与传统单一的信道估计技术相比,该方法具有较低的复杂度和较好的估计性能,仿真实验证明了该算法的有效性。  相似文献   

9.
基于判决反馈前馈的RSDFF-PSP盲分离算法   总被引:2,自引:0,他引:2       下载免费PDF全文
崔鹏辉  熊涛  江桦  曹凯 《电子学报》2016,44(3):633-638
针对信道记忆长度较大时,成对载波多址(Paired Carrier Multiple Access,PCMA)混合信号单通道盲分离复杂度高的问题,本文提出一种新型的减状态判决反馈前馈逐幸存路径处理(Reduced-State Decision Feedback-Feedforward Per-Survivor Processing,RSDFF-PSP)分离算法.该算法先利用截短逐幸存路径处理(Per-Survivor Processing,PSP)算法得到预判决,忽略掉前导和后尾干扰的影响,将复杂度控制在能够容忍的范围内;然后分别设计全局判决反馈滤波器和延时判决前馈滤波器,利用分支路径度量的预判决结果反馈以及延时前馈来补偿前导和后尾干扰带来的性能损失,并结合二次判决获得了更佳的分离性能.仿真实验结果表明,RSDFF-PSP算法在减少复杂度的同时能够最大限度地得到逐幸存路径处理最大似然序列估计(Per-Survivor Processing Maximum Likelihood Sequence Estimation,PSP-MLSE)的性能,实现复杂度和性能的良好折中.  相似文献   

10.
宋梁  胡波  凌燮亭 《电子学报》2002,30(5):723-726
在移动通信系统中,由于衰落和多普勒效应,为了实现基于Viterbi算法的极大似然序列估计(MLSE),需要不断跟踪信道参数变化.本文首先提出了一种新的基于插值的信道估计方法ICP(Interpolating channel processing),并给出了该方法的两种实现形式,同已有的一些算法的比较结果表明:新方法具有更小的计算复杂度,误码率更低.同时,本文对如何降低Viterbi算法(VA)的计算复杂度也作了探讨.通过采用自适应减小计算复杂度的算法(ATA),本文提出的ICP算法具有更优的性能.  相似文献   

11.
In this paper, a comparison study is proposed between two recent algorithms which both perform joint channel and data estimation. The first one is the well known psp : per survivor processing algorithm and the second is called adaptive bloc sequence estimation (bse). Compared to the existing literature, we add, for our comparison study, the case of trellis coded transmissions combined with interleaving and deinterleaving techniques which are now currently employed for digital communications.  相似文献   

12.
An adaptive trellis-encoding scheme, using the Viterbi algorithm for trellis search and the Kalman algorithm for adaptive adjustment, is described. The encoder is comprised of a fixed precoder and a time-varying trellis coder in tandem. The source decoder is timevarying with the time-varying part being represented by a feed forward finite-state machine (FSM). Adaptive trellis encoding requires the presence of a local FSM to monitor the adaptive encoding operation. The absence of the source signal at the decoder requires the transmission of a side-information for the mechanization of the adaptive operation of the source decoder. The transmission rate of the proposed adaptive trellis-encoding scheme is(1 + 1/K_{p})/Mbits per source symbol, whereMis the block size which the precoder maps source symbols onto an intermediate signal set before trellis coding and Kpis the update period. Results obtained in the encoding of iid binary, autoregressive, and video sources are presented.  相似文献   

13.
该文提出了一种新的离散数字信道盲估计算法,运用格状图中的一步支路转移规则,大大削减了最佳估计所要求的计算量,文中首先介绍了符合最大似然序列估计(MLSE)准则的信道最佳盲估计算法,然后阐述了运用格状图中的一步支路转移准则对格状图进行筛选的基本思想,接着详细介绍了本算法,最后通过数值仿真研究了本算法的性能。  相似文献   

14.
In this paper, a novel trellis source encoding scheme based on punctured ring convolutional codes is presented. Joint source and channel coding (JSCC) using trellis coded continuous phase modulation (CPM) with punctured convolutional codes over rings is investigated. The channels considered are the additive white gaussian noise (AWGN) channel and the Rayleigh fading channel. Optimal soft decoding for the proposed JSCC scheme is studied. The soft decoder is based on the a posteriori probability (APP) algorithm for trellis coded CPM with punctured ring convolutional codes. It is shown that these systems with soft decoding outperform the same systems with hard decoding especially when the systems operate at low to medium signal-to-noise ratio (SNR). Furthermore, adaptive JSCC approaches based on the proposed source coding scheme are investigated. Compared with JSCC schemes with fixed source coding rates, the proposed adaptive approaches can achieve much better performance in the high SNR region. The novelties of this work are the development of a trellis source encoding method based on punctured ring convolutional codes, the use of a soft decoder, the APP algorithm for the combined systems and the adaptive approaches to the JSCC problem.  相似文献   

15.
The idea of adaptive state allocation (ASA) algorithm is used in this paper to substantially reduce the computational complexity of the maximum-likelihood sequence detection and estimation (MLSD/MLSDE) receiver without a significant degradation in its performance. In the ASA algorithm, the total number of states assigned to the trellis and the number of states selected from the entire set are changed adaptively based on the short-term power of the channel impulse response (CIR) or its estimate. The ASA algorithm is a combination of two methods: adaptive threshold (AT) and adaptive state partitioning (AP). In the AT method, a threshold value is formulated based on the probability of removing the correct state in the trellis diagram. At each time, only the paths whose costs are less than the minimum cost (corresponding to the best survivor path) plus the threshold value are retained and are extended to the next trellis stage. The AT method significantly reduces the computational complexity of the regular MLSDE mostly at high signal-to-noise ratio (SNR) with a negligible loss in performance. Simulation results for fading channels show that the AT method typically selects one trellis state (the minimum possible number of states) at high SNRs. In the AP method, the branch metrics are fused and diffused adaptively by using the Kullback-Leibler (KL) distance metric invoked for quantifying the differences between the probability density functions of the correct and incorrect branch metrics in the trellis. The adaptation is done such that the channel coefficients with short-term power less than a threshold are assumed to be zero in computing the branch metrics. The AP method decreases the computational complexity of the regular MLSDE at low SNRs  相似文献   

16.
The authors investigated the detection of trellis codes designed for channels that are intersymbol interference free when they operate in the presence of intersymbol interference. A well-structured reduced-state sequence estimation (RSSE) algorithm is described which can achieve the performance of maximum-likelihood sequence estimation (MLSE) with drastically reduced complexity. Well-defined reduced-state trellises are first constructed by merging the states of the ML supertrellis using set partitioning principles. Then the Viterbi algorithm is used to search these trellises. A special case of RSSE, called parallel decision-feedback decoding, uses the encoder trellis, yet on channels with large attenuation distortion it can provide a significantly better performance than linear equalization. The performance of RSSE is examined analytically and through simulation, and then compared to that of MLSE and ideal decision-feedback equalization. It is noted that the performance advantage of RSSE can be obtained without significantly increasing the decoding delay or complicating an adaptive implementation  相似文献   

17.
An iterative receiver for a space-time trellis coded system in frequency-selective fading channel is proposed. It performs channel gain estimation and sequence detection by using the expectation-maximization (EM) algorithm. Channel order estimation is included in the receiver to avoid unnecessary trellis computations by using the conditional model order estimator (CME). In addition, three modifications to the original CME criterion are proposed to improve the estimation accuracy. Simulation results show that the proposed receiver has a slight degradation in frame error rate performance to the known channel maximum likelihood receiver. Moreover, it outperforms the conventional fixed long-tap length EM receiver with a lesser complexity. Furthermore, the proposed modifications to the CME criterion improve the channel order estimation accuracy, thus minimizing unnecessary computations.  相似文献   

18.
本文提出一种针对空时格形码的软判决自适应双向解码算法.通过执行双向解码,该解码算法充分利用了TDMA下行链路相邻时隙的前导序列,并给出高质量的软判决解码输出;同时,所提出的两步最小均方算法以较低的运算开销实现了对时变信道的自适应跟踪.文章最后给出计算机仿真结果.  相似文献   

19.
本文结合正交频分复用(OFDM)、格形编码调制(TCM)与差分编码,提出一种使用子信道交织技术的差分TC—OFDM系统,并在此基础上将信道估计引入系统接收机,提出了与解码相联合的SEWRLS自适应信道估计方法。计算机仿真结果表明,本文提出的联合系统能有效地克服宽带无线通信中的多径衰落,并在快衰落环境中具有很强的抗信道干扰能力。  相似文献   

20.
In the context of per-survivor processing, an adaptive decoder for a space-time trellis code is proposed which exploits the accelerated self-tuning least-mean-square algorithm for tracking the fading channel. The proposed decoder provides good performance on slowly and moderately fast time-varying wireless channels  相似文献   

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