期刊文献+
共找到4篇文章
< 1 >
每页显示 20 50 100
网络传输中数据加密技术的研究 被引量:1
1
作者 时华 《科技信息》 2006年第11X期27-27,30,共2页
计算机网络中的数据总是通过介质传送,所以数据常常出现被攻击者截取、中断、篡改、伪造等安全性问题。随着数字签名、身份验证、数据加密技术的应用,数据安全问题得到了缓解,尤其是数据加密技术使网络数据传输更加安全。本文介绍了数... 计算机网络中的数据总是通过介质传送,所以数据常常出现被攻击者截取、中断、篡改、伪造等安全性问题。随着数字签名、身份验证、数据加密技术的应用,数据安全问题得到了缓解,尤其是数据加密技术使网络数据传输更加安全。本文介绍了数据加密技术的基本原理,重点研究了DES、RSA数据加密技术,并对其算法的优缺点进行比较探讨,最后介绍了一种安全性更好的复合加密技术。 展开更多
关键词 数据加密DES算法 RSA算法 数据安全 网络传输中
下载PDF
Robust Transmission for Cognitive Relay Networks 被引量:1
2
作者 Cao Zhigang Wang Jianyu +2 位作者 Liu Juan Wang Xijun Chen Wei 《China Communications》 SCIE CSCD 2012年第1期1-12,共12页
In cognitive relay networks, the transmission of Secondary Users (SUs) suffers from the activity of Primary Users (PUs) and wireless channel fading. Therefore, how to achieve robust transmission for cognitive rela... In cognitive relay networks, the transmission of Secondary Users (SUs) suffers from the activity of Primary Users (PUs) and wireless channel fading. Therefore, how to achieve robust transmission for cognitive relay networks is a challenging task. In this paper, we propose a relaying transmission scheme which exploits robust beamforming at the physical layer and rateless codes at higher layers. We derive the optirml beamforng weight vector and analyze the perforrmnce of the pro- posed scheme when the channel estirmtion is not accurate between two SU nodes. We also study how the anaount of channel information between SU and PU impacts the system perforroance. Sinlation results validate our theoretical analysis and demonstrate that the proposed scheme can signifi- cantly enhance the system throughput. 展开更多
关键词 cognitive radio relaying transmission robust beamforrning rateless codes
下载PDF
Outage Probability Minimization for Cognitive Relay Network Under Interference Power Constraints
3
作者 岳文静 郑宝玉 +1 位作者 孟庆民 谢培中 《Transactions of Tianjin University》 EI CAS 2011年第3期208-214,共7页
A cognitive relay network model is proposed, which is defined by a source, a destination, a cognitive relay node and a primary user. The source is assisted by the cognitive relay node which is allowed to coexist with ... A cognitive relay network model is proposed, which is defined by a source, a destination, a cognitive relay node and a primary user. The source is assisted by the cognitive relay node which is allowed to coexist with the primary user by imposing severe constraints on the transmission power so that the quality of service of the primary user is not degraded by the interference caused by the secondary user. The effect of the cognitive relay node on the proposed cognitive relay network model is studied by evaluating the outage probability under interference power constraints for different fading environments. A relay transmission scheme, namely, decode-and-forward is considered. For both the peak and average interference power constraints, the closed-form outage expressions are derived over different channel fading models. Finally, the analytical outage probability expressions are validated through simulations. The results indicate that the proposed model has better outage probability than direct transmission. It is also found that the outage probability decreases with the increase of interference power constraints. Meanwhile, the outage probability under the average interference power constraint is much less than that under the peak interference power constraint when the average interference power constraint is equal to the peak interference power constraint. 展开更多
关键词 cognitive radio relay networks outage probability power control
下载PDF
Power-line Modem over the Low Voltage Grid Using Direct Sequence Spread Spectrum Techniques
4
作者 A. Mahgoub H. Abdeel-Baky E. El-Badawy 《Journal of Energy and Power Engineering》 2011年第6期562-568,共7页
Power-line networks are designed to deliver electricity. They reach most of the domiciles and other buildings nowadays, so most of the people have access to it. On the other hand the backbone for the communications ne... Power-line networks are designed to deliver electricity. They reach most of the domiciles and other buildings nowadays, so most of the people have access to it. On the other hand the backbone for the communications networks is not available in all countries especially the developing ones. A high cost and changing the design for the networks may be needed to construct this backbone. If data can be transmitted over the power-line networks, a recognized cost and time save can be achieved. In Egypt, the infrastructure is not always available for constructing a communications network backbone due to the already designed buildings before the need for these backbones. In this paper, we overcome this problem by designing a reliable Power-line Modem that operates safely on the low voltage grid. The modem is based on the Direct Sequence Spread Spectrum technique. It uses the mains zero crossing as an efficient way for the synchronization between the transmitter and the receiver. The Modem takes into account the problems of the Power-line including noise, attenuation and impedance dismatching. 展开更多
关键词 Power-line modem DS/SS micro-controller (firmware) low voltage grid.
下载PDF
上一页 1 下一页 到第
使用帮助 返回顶部