基于扩频CDMA的数字盲水印算法

数字水印技术要求所构造的算法，具有很强的鲁棒性（抗攻击能力）。在数字水印技术中引入扩频技术，提高了数字水印的鲁棒性，但同时却使嵌入信息量减小了。丈中在引入CDMA技术，进一步增强鲁棒性，同时也使嵌入的信息量得到了提高。仿真实验表明：所提出的算法具有很强的鲁棒性、透明性，而且误码率较小，在很强的干扰下，仍能提取出水印。     

A real-time dual watermarking algorithm of H.264/AVC video stream for Video-on-Demand service

A real-time dual watermarking algorithm of H.264/AVC compressed video is proposed for Video-on-Demand (VOD) service. The copyright information and user information are modulated by CDMA spreading strategies as watermark. At the encoder side, copyright information is embedded into the first non-zero coefficient of Intra 4 × 4 coded blocks in the luminance components of I frames. An effective error compensation mechanism is simultaneously introduced into the embedding process, which strictly restricts the distortion caused by quantization and watermark embedding within a step size of quantization. At the server side, a XOR based mapping rule is utilized for watermark embedding because the number of non-zero coefficients after quantization is quite less in P frames. Every two bits of the private user information is mapped to three non-zero coefficients of P frames. Experimental results on test sequences demonstrate that the proposed approach has just slight influence on bit rate and PSNR with real-time performance for VOD services, and achieves the dual purposes of copyright protection and pirate tracking.     

JPEG2000小波变换仿真

提出一种基于JPEG2000中推荐的提升结构的5/3小波变换硬件实现方案。该方案在加载数据的同时进行边界扩展,无须对运算电路进行逻辑控制,可以复用加法器,提高了资源利用率。该方案在FPGA上仿真通过。     

基于VB.NET的商位出租管理系统设计与实现

随着商场经营模式的转变,商位的出租的管理工作变得复杂,工作量大。计算机信息化管理是解决这个问题的最好的办法。论述了基于VB.NET开发平台商位出租管理系统的开发过程。本系统以SQL Server 2000为数据库,以VB.NET为开发工具,实现了出租合同管理、出租收费管理,为管理者带来极大的方便。     

Optimum Uplink Power/Rate Control for Minimum Delay in CDMA Networks

We derive a new joint power and rate control rule with which we can minimize the mean transmission delay in CDMA networks for a given mean transmission power. We show that it is optimal to respectively control the power inverse‐linearly and the rate linearly to the square root of channel gain while maintaining the signal‐to‐interference ratio at a constant. We also show that the proposed joint power/rate control rule achieves excellent performance results in terms of the probability of the instantaneous delay being within a target delay against one‐dimensional control schemes.     

cdma2000 1x无线组网方案

本文详细论述了cdma20001x的无线网络结构，同时提出了在IS—95A网络上发展cdma20001x的一些组网方案，作出了相应的比较，并对组网中1x基站的覆盖问题进行了分析。     

DS/CDMA的数据检测技术

介绍了DS／CDMA移动通信系统降低误码率和提高系统容量关键技术之一的数据检测技术。     

A Study of Handoff in CDMA Systems

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CDMA和WCDMA系统室外邻频干扰问题研究

分析了由于CDMA（码分多址）系统与WCDMA（宽带码分多址）系统频段上相邻所造成的系统性能影响，建立了一个采用接收机灵敏度指标作为系统性能恶化和干扰程度的衡量指标的系统间邻频干扰模型。在评估灵敏度与干扰之间的影响基础上，对系统共存所需的空间隔离度进行计算，并且在CDMA和WCDMA共站址的环境下进行验证，实验结果有效的验证了理论仿真模型。结果表明通过适当降低接收机灵敏度，在满足相关协议要求的情况下，能够有效的减少系统间干扰的影响，达到系统共站址和共存的目的。该模型也可以适用于其他2G通信系统与WCDMA系统共存的干扰分析。     

WiMAX的技术亮点和市场策略

文章从WiMAX成为3G新标准说起,着重介绍了WiMAX的技术优势及其市场策略,简单阐述了作者对WiMAX进入3G标准家族的感受和启迪。