RCPT码及其在移动通信中的应用

由于无线信道的时变、高误码等特性，要求信道编码方式有较强的抗误码能力，而且能够自适应无线信道状态的变化。码率匹配删余Turbo码（RCPT）能实现这样的编码要求，并且能提供适应不同需要的不等差错保护（UEP）。介绍了RCPT码在移动通信中的应用，讨论了新的自适应编码调制及不等差错保护方案。     

一种基于RCPT码的混合ARQ方法及其在衰落信道下的性能

本文基于码率匹配截短Turbo(RCPT-Rate Compatible Punctured Turbo)码,综合利用"码字校验交替重传"方案及Chase组合技术,提出了一种新型混合ARQ(Hybrid Automatic Repeat reQuest)方法,并进一步在瑞利衰落信道上对该方法的性能进行了仿真验证,同时将其与几种现有基于RCPT码的混合ARQ方法进行了比较.数值结果表明,本文所提方法能以较低的系统实现复杂度获得较好的性能.     

移动通信中基于Turbo码的混合ARQ方案

在移动环境中，由于信道的时变特性，单纯的FEC或ARQ机制往往无法提供所希望的系统性能。为了提高数据及图像的传输可靠性，需采用ARQ与FEC相结合的混合ARQ差错控制方案。首先介绍了几种常见的以Turbo码作为纠错码的混合ARQ方案，然后研究了基于Turbo码组合译码的有限次重传混合ARQ方案，给出了传输方案及组合译码算法。仿真结果表明，低Eb/No时，该方案对通过率有明显改善。     

无线数据传输中的混合ARQ

本文针对无线数据传输中的混合ARQ,介绍了混合ARQ的基本概念和技术,重点分析评述了用于混合ARQ系统中的各种包合并方案和相关的纠错编码技术,并对混合ARQ的相关研究工作进行了展望.     

基于校正子的第一类混合ARQ及其性能分析

基于校正子的计算提出了一种第一类混合ARQ (HARQ) 方案,该HARQ采用Reed-Solomon (RS)码作为纠错子系统,将检错功能巧妙融于译码过程中。对系统误比特率和吞吐量的分析与仿真表明,短码宜采用前向校正子结构,长码宜采用后向校正子结构,而系统的吞吐量与可靠性之间的最佳折衷,可以通过选择恰当的最大重传次数实现。     

无线光通信中RCPT/ARQ自适应 差错控制机制的研究

为了克服无线光通信中的光强闪烁、大气衰减等信道干扰,本文结合无线光信道下Turbo码迭代译码算法,分析了RCPT码的穿孔图案特性,在此基础上完整给出了无线光通信系统RCPT/ARQ自适应差错控制方案,仿真表明RCPT/ARQ自适应差错控制方案显著提高了链路的吞吐量和稳定性.同时结合无线光信道的特性,提出了RCPT/ARQ机制下的排序重发策略,进一步优化系统在恶劣信道条件下的链路吞吐量.     

M步混合ARQ系统时延性能分析

为保证数据传输的可靠性,多种ARQ（自动请求重传）协议被提出和采用。论文针对多种ARQ／混合ARQ协议提出了一个一般化、系统化的时延分析模型,并采用信号流图理论及梅逊公式给出了M步混合ARQ控制系统的时延性能分析结果,为多种ARQ／混合ARQ协议的时延性能分析提供了一种系统化的有效分析方法。     

基于RCPT编码的自适应选择合并混合ARQ算法

混合自动重传请求（ARQ）作为一种差错控制技术被采纳为3GPP长期演进项目（LTE）的关键技术。基于速率兼容截断Turbo（RCPT）编码的混合ARQ算法,因其性能优异、实现复杂度低而被广泛关注。传统混合ARQ算法主要包括Chase合并方式混合ARQ,其在高信噪比条件下提供较大的性能增益;以及增量冗余（IR）方式混合ARQ,其在低信噪比条件下提供了更精确的速率控制。本文结合现有方法提出了一种基于RCPT编码的自适应选择合并混合ARQ算法,它在不同信噪比条件下自适应地选择Chase合并方式混合ARQ与IR方式混合ARQ,并且在接收端自适应地选择合并可靠性较高的传输码块。本文对其在瑞利衰落信道中的性能作了理论分析,并且进行了仿真,同时与传统的Chase合并方式混合ARQ以及IR方式混合ARQ作了性能比较。比较结果显示本文的算法在瑞利信道中比传统算法具有更为优异的性能以及相似的复杂度。     

Performance of Hybrid ARQ Schemes for the Mobile LEO Satellite Channel

This paper investigates the performance of hybrid ARQ schemes for the mobile Low Earth Orbit (LEO) satellite channel. The proposed schemes adapt their characteristics to the time-varying behavior of the channel. To obtain an unbiased comparison of different ARQ schemes an approximated analytical method is adopted. More precisely, the sphere-packing bound is used to estimate the best possible performance of a hybrid ARQ scheme. To assess the accuracy of the bound, simulation results, based on the use of turbo codes, are also presented. This revised version was published online in July 2006 with corrections to the Cover Date.     

A Model for the Performance Evaluation of Packet Transmissions Using Type-II Hybrid ARQ over a Correlated Error Channel

Type-II Hybrid-ARQ (Type-II HARQ) has been shown, under certain circumstances, to increase the efficiency and reduce loss of data transmissions over a wireless channel. However, it is difficult to predict how it will perform when transmission symbol errors are correlated. We present a computationally efficient approach to the performance evaluation of packet transmissions over a wireless link employing Type-II HARQ error mitigation when the physical channel is subject to correlated transmission symbol errors. This provides a tool for static or online optimization of system parameters. We present numerical results for a wide range of channel statistics, illustrating the effect of bit error correlation, bit error rate, and block size on packet latency and loss rate.     

Analysis of Serial and Hybrid Concatenated Space-Time Codes Applying Iterative Decoding

In this letter, we investigate serial and hybrid concatenated space-time (SC-ST and HC-ST) codes applying iterative decoding topologies. The coding operations are based on the concatenation of convolutional coding, interleaving, and space-time coding along with a multiple-transmitter/multiple-receiver diversity system. Through the analysis of the SC-ST and HC-ST coding systems, improved design specifications can be selected for the component encoders with considerations of the wireless channel characteristics. Based on the iterative decoding process and the optimum parameter selection operations, a considerable improvement in the error rate performance is obtained. For the applied specs, the results indicate that at the frame error rate (FER) 10⁻² level the SC-ST coding system provides a coding gain of approximately 3 dB in comparison to the Tarokh, Seshadri, Calderbank (TSC) space-time (ST) code [1], where the HC-ST coding system provides an additional coding gain of approximately 1 dB beyond the SC-ST code.     

Error Rate and Capacity Analysis for Incremental Hybrid DAF Relaying using Polar Codes

The deployment of an incremental hybrid decode-amplify and forward relaying scheme is a promising and superior solution for cellular networks to meet ever-growing network traffic demands. However, the selection of a suitable relaying protocol based on the signal-to-noise ratio threshold is important in realizing an improved quality of service. In this paper, an incremental hybrid relaying protocol is proposed using polar codes. The proposed protocol achieves a better performance than existing turbo codes in terms of capacity. Simulation results show that the polar codes through an incremental hybrid decode-amplify-and-forward relay can provide a 38% gain when γ_th(1) and γ_th(2) are optimal. Further, the channel capacity is improved to 17.5 b/s/Hz and 23 b/s/Hz for 2 × 2 MIMO and 4 × 4 MIMO systems, respectively. Monte Carlo simulations are carried out to achieve the optimal solution.     

某些非线性码的检错性能与VG限之关系

本文讨论了某些非线性码的检错性能与渐近ＶＧ限之关系，证明了不满足渐近ＶＧ限的非线性同距离分布码不是检错好码。     

RAID6编码的扩展算法及性能研究

 RAID6编码根据其码字结构可以分为水平码和垂直码两大类.RAID6水平码可以很容易的扩展至任意码长,而RAID6垂直码通常具有码长的限制.本文提出一种针对RAID6垂直码的码长扩展算法,该算法通过校验块变更的方法,可以将RAID6垂直码扩展至任意码长.该算法可以保持RAID6垂直码的MDS特性.本文研究了RAID6编码的扩展算法在应用于各种RAID6编码时对其性能的影响,揭示出RAID6编码在进行扩展时的性能变化规律.