比特交织IRA码编码调制

提出了不规则重复累积（IRA）码实现比特交织编码调制（BIRACM）的设计方案，并在AWGN和Rayleigh平衰落信道下进行了仿真。仿真结果表明：BIRACM的性能优于传统的网格编码调制和比特交织编码调制。     

数字通信中数据压缩编码与解码技术

数据压缩编码与解压解码技术是目前应用的数字通信系统中的关键技术之一。本文介绍常用的数据压缩编码与解码技术及其最新研究进展，包括语音压缩编码、图像压缩编码与解码技术、多媒体数据压缩域处理技术以及差错控制编码与解码技术等。     

网格编码MQAM直扩多址系统的性能分析

本文将非恒包络高效网格编码调制ＴＣ－ＭＱＡＭ应用于瑞利慢衰落信道下的直接序列扩频多址系统中。针对衰落信道和ＴＣ－ＭＱＡＭ的特点，提出了一种分析ＴＣ－ＭＱＡＭ用于衰落信道下ＤＳ／ＳＳＭＡ系统性能的方法，数值模拟表明在系统用户数、用户信源比特速率以及码相同的条件下，本文所构造的非恒包络１／４ＴＣ－１６ＱＡＭ性能优于同状态数３／４ＴＣ－１６ＱＡＭ和恒包络２／３ＴＣ－８ＰＳＫ。这说明通过增大最小分支数等适     

Turbo码在无线移动通信中的应用

首先分析了Turbo码的基本编、译码结构与原理，然后探讨了它在无线移动通信系统中的几个具体应用。     

自适应调制与编码系统及其在WCDMA中的应用

本文主要讨论自适应调制与编码系统(Adaptive Modulation and Coding system）的原理，介绍AMCS实现的几个关键技术，包括RCPT（速率适配凿孔turbo）码、高阶调制、H-ARQ和MIMO（多输入多输出）系统。介绍了在WCDMA的高速下行分组接入业务（HSDPA）中使用的自适应调制编码机制，并讨论了可能增加的设备复杂度。     

基于正交化的时频组合调制系统的性能分析

本文基于泛函分析中内积空间理论建立了信号空间，将时频信号表示成相互正交的矢量，然后对时频组合调制系统进行了性能分析。给出了在ＡＷＧＮ信道匹配子空间解调器的条件下，对四时四频系统进行性能分析的过程，分析的结果得到了计算机模拟试验的验证。文中最后也推广给出Ｍ进制ｎ时ｎ频时频组合调制的误码率公式。     

Turbo码和高频谱利用率调制技术

<正> 我国外贸体制如何进一步深化改革,是直接关系到我国外贸企业在国际市场上生存与发展的重要问题,也一直是我国外贸理论界和外贸实际工作者研究和讨论的热点。笔者认为,以邓小平建设有中国特色社会主义理论为指导,可把视野再拓宽一些,思想再解放一点,对国有外贸企业现行的组织形式再进一步作调整,组建区域性国际贸易集团,就深化我国外贸企业改革进行一个大胆尝试。本文就此作一探讨。     

语音的波形编码及其实时执行

数字语音编码主要解决如何压缩输出信息的比特率,以提高线路复用率。本文在简述了有关这一领域的概况之后,着重阐述了三种语音波形编码的主要原理及其实时执行方式,即自适应差分脉码调制(ADPCM);子频带编码(SBC)及自适应变换编码(ATC)。前两种结构较简单,可用单片数字信号处理机(DSP)获得实时实现;后一种结构复杂,且进行分块处理,故实时执行时需采用数组处理机。三种方式分别将比特率压缩至32、16及9.6Kbit/s的范围内。文中对所涉及的硬件结构亦作了一定的介绍。     

Turbo码的Taylor-Log_MAP译码算法

以Turbo码基本理论和算法为基础,依据无线信息传输的实际要求和Taylor级数的基 本原理,提出了一种Turbo码的Taylor-Log-MAP高效译码算法。该算法对基本的Log-MAP 算法中K运算利用Taylor级数进行展开,针对实际的信道需求对展开式进行截断,实现了Tur bo码 的最佳译码。与传统的对数域最大后验概率译码算法相比,该算法基本保持了优良的译码 性能,同时避免了复杂的对数运算,减小了运算量。仿真结果表明,与现 有的RS码性能相比,使用Turbo码可以获取5 dB的信噪比增益。     

Turbo码解码过程中的加权算法

本文通过调整迭代解码过程中系统位接收值的加权系数，提出了一种Turbo码加权迭代解码算法。该算法改变了迭代运算后Turbo码解码器输出软值中系统位接收值信息和它的外部估计信息的比重，使Turbo码无论在低信噪比或是在高信噪比时均具有优良的纠错性能。仿真结果显示，采用Turbo码加权迭代解码算法，不仅能提高Turbo码的收敛速度，而且能进一步降低Turbo码解码时的地板值，使Turbo码的比特误码率在高、低信噪比时都能够得到进一步改善。     

A Critical Analysis of the Accounting Industry’s Voluntary Code of Conduct

The public accounting industry’s voluntary code of conduct in the United States is the American Institute of CPA’s Code of Professional Conduct. Based on our analysis, we conclude that the accounting industry’s current code is limited in its ability to serve the public interest in three respects. Specifically, the code is input-based, requires no third-party attestation of compliance with the code, and contains no public reporting process of code compliance/noncompliance at the accounting firm level. We propose that the accounting profession should reorient its largely input-based Code of Professional Conduct to include output-based performance measurements. We also conclude that third-party attestation of compliance with the profession’s code would help to promote compliance. Finally, we maintain that the accounting industry should initiate a public reporting process at the individual accounting firm level. Such a requirement would add a degree of public accountability as to whether a firm complies or fails to comply with the industry’s voluntary code of conduct. John D. Neill, Ph.D., CPA, is a professor of accounting at Abilene Christian University and has previously published articles in numerous journals including the Journal of Business Ethics, Journal of Accounting Literature, Accounting Horizons, Advances in Accounting,theFinancial Analysts Journal,and theJournal of Accounting, Ethics, and Public Policy. O. Scott Stovall, Ph.D., is an assistant professor of accounting at Abilene Christian University and has published articles in the Journal of Business Ethics, Management Accounting Quarterly, and Cases from Management Accounting Practice. Darryl L. Jinkerson, Ph.D., is an assistant professor of management and chair of the Management Sciences Department at Abilene Christian University and was formerly the Director of Assessment and Measurement for Arthur Andersen.     

Impacts of Corporate Code of Conduct on Labor Standards: A Case Study of Reebok’s Athletic Footwear Supplier Factory in China

This study examines the social impacts of labor-related corporate social responsibility (CSR) policies or corporate codes of conduct on upholding labor standards through a case study of CSR discourses and codes implementation of Reebok – a leading branded company enjoying a high-profiled image for its human rights achievement – in a large Taiwanese-invested athletic footwear factory located in South China. I find although implementation of Reebok labor-related codes has resulted in a “race to ethical and legal minimum” labor standards when notoriously inhumane and seriously illegal labor rights abuses were curbed, Chinese workers were forced to work harder and faster but, earned less payment and the employee-elected trade union installed through codes implementation operated more like a “company union” rather than an autonomous workers’ organization representing worker’ interests. In order to explain the paradoxical effects of Reebok labor-related codes on labor standards, I argue the result is determined by both structural forces and agency-related factors embedded in industrial, national and local contexts. To put it shortly, I find the effectiveness of Reebok labor-related codes is constrained not only by unsolved tension between Reebok’s impetus for profit maximization and commitment to workers’ human rights, but also by hard-nosed competition realities at marketplace, and Chinese government’s insufficient protection of labor rights. Despite drawing merely from a single case study, these findings illuminate key determinants inhibiting the effectiveness of labor-related CSR policies or codes in upholding labor standards, and hence two possible way-outs of the deadlock: (1) sharing cost for improving labor standards among key players in global supply chain; and (2) combining regulatory power of voluntary codes and compulsory state legislations. I would like to thank three anonymous referees for helpful comments on earlier version of this article. I also would like to express my appreciation to professor Pun Ngai, for her continuous guidance and support during the work on this article.