Turbo乘积码在卫星通信中的应用

介绍了一种性能卓越的前向纠错编码技术——Turbo乘积码(TPC)及其在卫星通信中的应用。首先对TPC的编码、解码的工作原理进行了简要的介绍,并阐述了TPC的优越性能:减少的带宽、增强的编码性能、减少的处理时延和良好的“软膝”特性。通过与传统的FEC性能进行比较,指出TPC在卫星通信领域中巨大的应用前景。     

Turbo乘积码技术及其性能研究

在分析Turbo乘积码的基本编译码原理的基础上,比较了未编码与编码后系统的差错性能,研究了选取不同分量码、不同迭代次数对TPC译码性能的影响。在不同迭代次数与分量码情况下,进行了仿真实验。仿真实验表明,在相同的差错性能条件下,采用TPC码能带来5~6 dB的编码增益。TPC译码算法简单,没有错误平层,硬件实现复杂度较小,是一种非常实用的信道编码方式。     

低密度校验码及其在图像传输中的应用

低密度校验(Low-Density Parity-Check,LDPC)码是一种基于图和迭代译码的信道编码方案,性能非常接近Shannon极限且实现复杂度低,具有很强的纠错抗干扰能力。该文深入研究了LDPC码的编码和译码基本原理,并将其应用于移动衰落信道图像的传输中,仿真结果表明LDPC码能为图像传输带来显著的性能提高,且系统复杂度低,译码时延短。     

一种低复杂度Turbo乘积码自适应Chase译码算法

针对Turbo乘积码(Turbo Product Codes, TPCs)中的译码问题,该文提出一种全新的低复杂度TPC自适应Chase迭代译码算法。与已有的报道不同,在译码过程中,新算法首先统计TPC码块内每一行(列)产生的代数译码后的备选序列与接收序列的相同最小欧氏距离的个数,然后根据统计结果,按照算法步骤调整译码所需的不可靠位数值。通过Monte Carlo仿真可验证,当TPC行列编码采用相同的扩展汉明码,且编码效率为0.879时,该算法与Pyndiah采用固定不可靠位数值迭代译码算法相比,在误码率BER为10-4处仅损失约0.08 dB的性能,但是译码平均复杂度降低可达到约40.4%。     

三维TPC译码器的设计及FPGA实现

Turbo乘积码（TPC）是一种性能优秀的纠错编码方法,它具有译码复杂度低、译码延时小等优点,且在低信噪比下可以获得近似最优的性能。介绍了基于Chase算法的三维TPC软输入软输出（SISO）迭代译码算法,提出了三维TPC译码器硬件设计方案并在FPGA芯片上进行了仿真和验证。测试结果表明,该译码器具有较高的纠错能力,满足移动通信误码率的要求。     

数字电路倍增设备低速率语音编码方案的选择

新一代数字电路倍增设备(DCME)中将采用更低速率的语音编码技术.文中介绍了几种ITU-T公布的低速率语音编码技术,对其时延、编码质量以及算法复杂度等进行了比较,最后就DCME的不同应用场合选择了适合的语音编码方案.     

Turbo乘积码在卫星ATM系统中的应用

Turbo乘积码(TPC)是一种性能优异的前向纠错编码技术.卫星ATM技术代表了卫星通信网络的研究方向.研究了TPC在卫星ATM系统中的应用方案.首先,分析了卫星信道对ATM信元传输带来的影响;然后对TPC的编、解码的方法进行了简要介绍,并阐述了TPC的优越性能;最后,提出了一种卫星ATM网络中应用TPC的解决方案,并通过仿真得到了该方案的性能曲线.仿真结果证明,TPC的应用能够大幅降低卫星信道的误码率,使ATM信元能够正确传输.     

基于VHDL的TPC译码器设计

Turbo乘积码是一种性能卓越的前向纠错码,具有译码复杂度低,且在低信噪比时可以获得近似最优的性能。介绍基于Chase算法的Turbo乘积码软入软出（SISO）迭代译码算法,提出基于VHDL硬件描述语言的TPC译码器设计方案,并在FPGA芯片上进行了仿真和验证。仿真结果证明该译码器有很大的实用性和灵活性。     

基于FPGA的TPC编译码器的设计与实现

Turbo乘积码(TPC)能够逼近Turbo卷积码的译码性能,同时复杂度低,且结构易于并行处理,为高速移动通信的数据传输解决了一项关键技术。文章设计了二维TPC的编译码器在FPGA上的开发结构,并在Altera公司的EP1C12芯片上实现了多种实用的编译码结构。     

基于停止集的喷泉编码有限长性能估计

喷泉编码是一类基于删除信道、面向数据分组的前向纠错编码技术。该文分析了停止集的尺度分布对固定码率喷泉编码解码性能的影响,提出了一种估算低误码条件下喷泉编码有限长性能的方法以及一种低复杂度的停止集尺度分布搜索算法。比较结果表明,该文给出的喷泉码解码性能上下界与实际仿真结果非常接近。     

宽带移动通信中Turbo乘积码的仿真研究

推出了一种新型的纠错码——Turbo乘积码(TPC),描述了Turbo乘积码的编译码基本思想,详细地分析了TPC的Turbo软迭代译码的核心思想,并对AWGN信道和瑞利衰落信道下的TPC的译码性能做了仿真分析,从仿真结果可以看出,在高编码效率时,TPC不仅具有更高的码率,而且可以获得很好的误码率性能,所以乘积码的软迭代译码方案有很好的应用性,在未来的宽带移动通信中具有广阔的应用前景。     

TPC编译码的硬件实现

首先介绍了TPC编译码的原理,并介绍了AHA公司生产的第一代TPC编译码芯片AHA4501,该芯片通过对内部寄存器的控制能够完成不同TPC码的编译码。在理论研究的基础上阐述了TPC硬件实现系统的设计方案。系统的外部电路基本上都由FPGA完成,重点介绍AHA4501芯片的初始化流程,使之能够正确完成TPC的编译码。     

On the performance of high-rate TPC/SPC codes and LDPC codes overpartial response channels

This paper evaluates two-dimensional turbo product codes based on single-parity check codes (TPC/SPC) and low-density parity check (LDPC) codes for use in digital magnetic recording systems. It is first shown that the combination of a TPC/SPC code and a precoded partial response (PR) channel results in a good distance spectrum due to the interleaving gain. Then, density evolution is used to compute the thresholds for TPC/SPC codes and LDPC codes over PR channels. Analysis shows that TPC/SPC codes have a performance close to that of LDPC codes for large codeword lengths. Simulation results for practical block lengths show that TPC/SPC codes perform as well as LDPC codes in terms of bit error rate, but possess better burst error statistics which is important in the presence of an outer Reed-Solomon code. Further, the encoding complexity of TPC/SPC codes is only linear in the codeword length and the generator matrix does not have to be stored explicitly. Based on. the results in the paper and these advantages, TPC/SPC codes seem like a viable alternative to LDPC codes     

基于FPGA的TPC编译码器设计与实现

介绍了Turbo乘积码(TPC)的编译码原理,并对TPC码字结构进行了分析。在高斯信道下给出了子码为扩展汉明码(64,57,4)的TPC码的误码率性能,并对编译码器的模块设计进行说明,同时采用Altera公司的EP2S180芯片完成了方案验证。结果表明,在系统时钟为100 MHz的情况下,译码时延约为44 μs,可较好地满足实时性需求。     

基于校验子的Turbo乘积码仿真研究

针对Turbo乘积码译码延时的问题,提出一种基于校验子的Turbo乘积码译码算法(S-TPC),该算法根据校验子的值采取不同方式对每行(列)进行译码,节省了一部分校验子为0的码字的硬判决译码运算量。仿真结果表明,S-TPC(32,26)在迭代4次时,能在不降低译码性能的情况下,减少近50%的计算量。     

Turbo product codes for FH-SS with partial-band interference

Turbo product codes (TPC) are investigated for use in frequency-hopping spread-spectrum (FH-SS) communications in partial-band interference. Binary orthogonal FSK is employed with noncoherent envelope detection. The Fossorier-Lin (1995) algorithm of soft-decision decoding based on ordered statistics is employed for soft-in/soft-out decoder instead of Chase (1972) algorithm to reduce the required E_b /N_J for a given packet failure probability. Performance of TPC for FH-SS with and without memory is evaluated by simulation. A numerical method to calculate the upper bound on performance is also given. The results show that the low-complexity TPC has a similar performance to the high-complexity convolutional turbo codes (CTC) for FH-SS without memory. For FH-SS with memory, full interleaving is used for TPC to achieve a good performance at low duty factors of partial-band interference     

Integrated MAP equalization and coding for optical-fiber-communication systems

In this paper, an integrated maximum a posteriori equalization and turbo product coding (IMAP-TPC) scheme for optical-fiber-communication systems (OFCS) is proposed. The scheme uses a probabilistic characterization of the electrical current in the presence of intersymbol interference (ISI) and noise to compensate their effects and improve the bit error rate. In the new IMAP-TPC scheme, TPC decoding is integrated with a symbol-by-symbol MAP detector. The MAP detector calculates the log-likelihood ratio of a received symbol using the conditional probability-density information and, hence, obtains a much more accurate reliability measure than the traditional measure used in the TPC decoder. The TPC was generated by serial concatenation of two Bose, Chaudhuri, and Hocquenghem codes with low overhead, which is a structure similar to a recently proposed hardware implementation of TPC decoder for optical systems. Simulation results with all-order polarization mode dispersion and amplified spontaneous emission noise demonstrate both the practicality and the effectiveness of the IMAP-TPC scheme for OFCS.     

Transmit Precoding Based Low Complexity Codebooks and Finite Feedback Rate for Space Shift Keying MIMO Systems

Transmit Precoding (TPC) considerably improves the performance of Space Shift Keying (SSK) systems. Codebook-based TPC is able to tackle several difficulties encountered by non-codebook TPC techniques. Channel State Information (CSI) is required at the receiver only, and the index of the best codeword is easily identified and fed-back from receiver to transmitter with low rate message. Motivated by these advantages, this paper contributes to the codebook-based TPC in the following aspects. First, the paper presents a Factorized form of the Full-Combination (FC) codebook with phase rotation only, and shows that only four phases are needed, which significantly simplifies practical implementation. As a second contribution, the paper introduces two statistically filtered codebooks: Index-Filtration FC and Average-Filtration FC. These codebooks considerably reduce system complexity due to their small codebook size, while maintaining almost the same BER of the FC codebook. As a third contribution, this paper proposes a new codeword selection criteria based on Long term statistics of the CSI (LCSI), instead of the conventional criteria using instantaneous CSI. This reduces the feedback rate of the index of the selected codeword while providing performance improvement over non-precoded SSK. Simulation results show the effectiveness of the proposed codebooks and the performance improvement with LCSI selection criteria.