基于衰落信道的Turbo码的设计与实现

Turbo码作为一种新颖的信道编码,可以获得接近香农理论极限的性能,IMT-2000已经将Turbo码作为第三代移动通信系统(3G)传输高速业务数据的信道编码标准之一.文中提出了一种在衰落信道下Turbo码的实现模型,并探讨了Turbo编、译码器的设计及其算法,最后用MATLAB语言完成了算法的仿真实现.仿真结果表明,在低信噪比的无线衰落信道中,Turbo码不仅可以获得更大的编码增益,有效地改善系统的性能,而且具有很强的抗衰落、抗干扰能力,在移动通信系统中有着很大的应用潜力.     

基于SC-FDE和Turbo码的图像传输技术

分析了单载波频域均衡技术和Turbo编译码技术,研究了基于这两种技术的无线图像传输方案,并对联合SC-FDE和Turbo码图像传输方案进行了数值仿真研究。仿真结果表明,把SC-FDE技术和Turbo码技术结合应用到无线图像传输中可以明显提高接收图像质量,改善信噪比性能。相比较传统无SC-FDE的图像传输方案,在误码率为10-5时有约1.5dB的增益。从而表明,联合SC-FDE和Turbo码可以实现图像的更加可靠的传输,是实现图像的高速传输和高频谱利用率的有效方法。     

在卫星移动信道中不同条件下Turbo码的纠错性能研究

研究了采用Turbo码技术的抗衰落性能,首先分析了Turbo码在卫星移动遮蔽Rician衰落信道下的误差纠错性能限,然后通过计算机仿真模拟了三种不同的卫星移动衰落信道下Turbo码的性能,研究了不同衰落信道特性对Turbo码性能的影响情况,同时还讨论了在衰落信道下Turbo码的子码约束长度和交织器长度两个主要参数对性能的影响情况。     

短波信道下Turbo码性能仿真分析

短波通信具有抗毁性好,传输距离远的优势,但同时也存在信道变化大,可用频率难以预测的缺点。短波信道的时变性、多普勒频移以及多径衰落导致其传输性能不稳定,信道编码是对抗信道衰落的一种重要技术,将编码增益极高的Turbo码引入到短波数字通信中,可大大提高短波通信的可靠性。基于Watterson短波信道模型,仿真了典型短波信道下Turbo码的性能,得出了一系列量化性能指标,对实际工程应用具有一定的指导意义。     

RS-Turbo级联码的性能仿真及其在图像传输中的应用

RS码是一种纠突发错误能力很强的信道编码方式,Turbo码是一种巧妙的将卷积码和随机交织器结合在一起,同时采用软输出并通过不断迭代的方法译码来逼近最大似然编码的一种新的纠错能力很强的信道编码方式;本文分析了两种编码方式并研究了将二者级联后RS-Turbo的性能,给出了将其级联码在图像传输中的应用.     

Turbo码与数字图像传输系统的结合方案探讨

本文研究了Turbo码与数字图像传输系统的结合方案。将Turbo码应用到采用MPEG—2标准的数字电视传输系统的信道编码中,并将Turbo码与RS码的级联方案进行了探讨。对探讨结果进行了计算机仿真,得到了相应的性能曲线。     

基于turbo码的DAB系统的仿真与分析*

提出一种以Turbo码作为数字音频广播系统(DAB)的信道编码方案,并在Matlab/Simulink平台中基于Turbo码作为信道编码建立了DAB传输系统.使用贝努利序列(Bernoulli Binary)模拟DAB系统中音频数据流进行了系统仿真,并将其与采用卷积码作为信道编码的结果进行了对比,结果证明本方案可以有效提高系统的抗干扰性能,Turbo码适用于在新一代数字音频广播系统中应用.     

基于OFMD的改进Turbo码图像传输系统应用

研究了正交频分复用（OFDM）技术以及Turbo编码技术在图像传输中的应用,并对利用OFDM改进的Turbo码图像传输系统进行了仿真研究。仿真结果表明,把OFDM技术和Turbo编码技术结合应用到无线信道图像传输中可以实现图像的更加可靠的传输。从而表明OFDM是一种改进Turbo编码,是实现图像的高速传输和高频谱利用率的有效方法。     

Turbo码及其在第3代移动通信中的应用

Turbo码是一类并行级联递归的系统卷积纠错编码 ,当交织长度足够长时 ,其性能接近仙农信道编码极限值。由于其很强的抗衰落性和抗干扰能力 ,Turbo码在第 3代移动通信系统IMT - 2 0 0 0中得到了广泛应用     

第四代移动通信系统中的信源信道联合编码技术

本文介绍了未来第四代移动通信系统中可能的联合编码框架,在分析基于小波变换的SPIHT算法和Turbo编 码算法的基础上,给出了一种改进的无线传输系统结构。仿真结果表明,这种利用信源特性进行信道编译码的方法能够有效 地降低时延,提高信道编码的纠错性能,适合于未来多媒体无线传输业务的需求。     

Design and analysis of turbo codes on Rayleigh fading channels

The performance and design of turbo codes using coherent BPSK signaling on the Rayleigh fading channel is considered. In low signal-to-noise regions, performance analysis uses simulations of typical turbo coding systems. For higher signal-to-noise regions beyond simulation capabilities, an average upper bound is used in which the average is over all possible interleaving schemes. Fully interleaved and exponentially correlated Rayleigh channels are explored. Furthermore, the design issues relevant to turbo codes are examined for the correlated fading channel. Turbo interleaver design criteria are developed and architectural modifications are proposed for improved performance     

Fast turbo codes with space‐time block codes in fast fading channels

In this paper, space‐time block coding has been used in conjunction with Turbo codes to provide good diversity and coding gains. A new method of dividing turbo encoder and decoder into several parallel encoding and decoding blocks is considered. These blocks work simultaneously and yield a faster coding scheme in comparison to classical Turbo codes. The system concatenates fast Turbo coding as an outer code with Alamouti's G2 space‐time block coding scheme as an inner code, achieving benefits associated with both techniques including acceptable diversity and coding gain as well as short coding delay. In this paper, fast fading Rayleigh and Rician channels are considered for discussion. For Rayleigh fading channels, a fixed frame size and channel memory length of 5000 and 10, respectively, the coding gain is 7.5 dB and bit error rate (BER) of 10^?4 is achieved at 7 dB. For the same frame size and channel memory length, Rician fading channel yields the same BER at about 4.5 dB. Copyright © 2013 John Wiley & Sons, Ltd.     

瑞利衰落信道下基于LDPC码USTM的MIMO系统

研究了一种联合低密度校验(LDPC,Low-Density Parity-Check)码和酉空时调制(USTM,Unitary Space-Time Modulation)技术在不相关瑞利平坦衰落(Rayleigh flat fading)下的多输入多输出信道(MIMO,Multiple-Input Multiple-Output)系统的性能.在无信道状态信息下,采用可并行操作的和积译码算法(SPA,Sum-Product Algorithm)的LDPCC-USTM级联系统具有优异的性能,并分析了不同LDPC码集下对系统性能的影响.仿真结果表明LDPCC-USTM级联系统比与未级联的相比有近23dB的编码增益,与基于Turbo码的USTM[6]系统相比有5dB多的编码增益,且基于非规则的LDPC码的级联系统比基于规则码有近1dB的编码增益.     

LDPC-COFDM系统在多径衰落信道下的性能分析

将正交频分复用(OFDM)技术应用于多径衰落信道下的高速数据传输是一个极富吸引力的方案,包括卷积码、RS码、Turbo码在内的多种纠错编码都曾被应用在OFDM系统中.最近,一种新的编码方案--低密度奇偶校验码(LDPC)引起了人们的注意.LDPC具有低的解码复杂度和逼近香农限的性能.文中仿真分析了LDPC-COFDM(编码正交频分复用)系统的性能,并与Turbo码系统进行了对比,结果表明该系统在多径衰落信道下显示出更为优越的性能.     

自适应调制编码的VBLAST系统研究

在高速下行分组接入（HSDPA）中,采用自适应调制编码（AMC）技术能提高下行信道传输数据的能力。仿真信道编码采用Turbo码,将自适应调制编码技术应用于VBLAST系统以进一步提高系统性能和容量。因此系统能选择调制编码方式和信道编码方式,又能对抗衰落引起的突发错误。对该系统进行仿真表明：自适应调制编码的VBLAST系统能有效地提高数据传输效率和传输质量。     

Channel codes based on hidden puncturing with applications to hybrid in band on channel digital audio broadcasting systems

In this work, a new approach of designing channel codes for partial band interference channels based on "Hidden Puncturing" is introduced. This technique does not require explicit estimation of the interferer. We investigate the performance of specially designed rate 1/2 convolutional codes with Viterbi decoding and rate 1/2 Turbo codes in an example scenario with partial band FM interference. For comparison, we also give results for Turbo codes for schemes with no interference. We show by means of simulations that for Gaussian as well as for a variety of multipath fading profiles, a significant Turbo channel coding gain compared to a conventional Viterbi system can be achieved. Thereby the performance of optimal combining, which requires optimal estimation of the interferer, can be approached very closely in various scenarios.     

第3代移动通信系统中的信道编码技术研究

第3代移动通信系统IMT2000是当前的研究热点,而信道编码又是其关键技术之一.第3代移动通信系统中的业务范围和数据传输速率都大有提高,因此信道编码在语音业务上除了继承第2代系统的前向纠错(FEC)卷积编码技术外,还采纳了以Turbo码为代表的纠错能力更强的、先进的编码技术.讨论了CDMA2000[1]系统中的纠错编码技术,尤其是Turbo码在其中的应用.     

高阶调制与好码的结合问题

本文从信道容量分析的角度，对多进制调制与信道编码好码结合问题进行研究，发展联合编码调制设计与编码调制分别独立设计之间容量没有显著区域。说明二进制好码同高阶调制直接级联，就能逼近信道容量，这也解释了目前文献结果和我们的仿真结果关于TTCM和PT－TCM结果基本一致的现象。     

Multilevel coded CPFSK systems for AWGN and fading channels

In this paper, we introduce multilevel coded continuous-phase frequency-shift keying (CPFSK) systems for both additive white Gaussian noise and fading channels based on multilevel coding and multistage decoding techniques. These schemes are designed under the constraint M⩾2P for M-ary CPFSK with modulation index J/P. In order to maintain the phase continuity property after multilevel coding, we use some specific set partitioning rules. We construct examples to show that the proposed systems outperform the corresponding conventional one-level schemes. For the fading case, we consider an ideal fading channel where adjacent fading symbols are assumed to be independent and a correlated fading channel where bit interleavers are needed at each coding level. The computer simulation results show that the proposed systems have bit-error performance and decoder complexity advantages over the corresponding reference codes taken from the literature. It is also shown that there is only a slight degradation on the bit-error performance for correlated fading, compared to the ideal fading case