通信的

Firstly the basic principle of OFDM and its anti-multi-path-fading are briefly introduced in this paper. Then basing on this point, we researched the basic principle, the coding designing and the algorithm of the signal detection of these MIMO-OFDM systems. At the same time, the performances of STBC-OFDM and SFBC-OFDM were analyzed and simulated under short wave circumstance, and got some useful conclusions, they have certain reference value for more research of short wave communication in future.

本文首先介绍了OFDM系统的基本原理以及它对抗多径的基本原理，然后在此基础上，对其所形成的几种MIMO-OFDM系统的基本工作原理，码字设计以及相应的信号检测算法进行了研究，详细分析研究了STBC-OFDM和SFBC-OFDM系统的性能并在短波信道下对其性能进行了仿真和对比分析，得出了有用的结论，这对以后短波通信的深入研究具有参考价值。

IPv6 routing algorithms in wireless sensor networks In wireless communication, energy consumption grows exponentially with the incensement of distance. Sensor nodes are usually equipped with limited energy and wireless sensor network coverage is usually very large.

3无线传感器网络中基于IPv6的路由算法无线通信的能量消耗随距离的增加而指数级增长，考虑到传感器节点的能量限制和网络覆盖区域大，无线传感器网络采用多跳路由的传输机制。

IPv6 routing algorithms in wireless sensor networksIn wireless communication, energy consumption grows exponentially with the incensement of distance. Sensor nodes are usually equipped with limited energy and wireless sensor network coverage is usually very large.

3无线传感器网络中基于IPv6的路由算法无线通信的能量消耗随距离的增加而指数级增长，考虑到传感器节点的能量限制和网络覆盖区域大，无线传感器网络采用多跳路由的传输机制。

Jochen Schiller is head of the Computer Systems and Telematics Working Group in the Institute of Computer Science,Freie Universitat Berlin,and a comsultant to several companies in the networking and commmunications business.

本书从计算机科学的角度涵盖移动通信的各个方面，还指出了不同技术解决方案的共同属性，并阐明众所周知的从固定网络到支持终端移动性和无线接入网络的各种业务和应用的集成。

Users' certificates are signed by CA and then respectively sent to each user to keep.The message and its digital signature are encrypted to transmit in the network without disclosure.The scheme proposed provides mutual authentication between the sender and the recipient,and the confidentiality,integrity and nonrepudiation of the interchanged messages are ensured.

通信的各方产生自己的私钥和公钥对，用户的证书由CA签发后交给用户保存，交换的消息和其签名等信息采用压缩加密传输，避免了消息在传输的过程中被第三者窃取或篡改，保证了数据的机密性、完整性和不可否认性。

Through to 'the intelligent visible doorbell systems' the topic study and the design, makes me to understand the AT89C51 monolithic integrated circuit the characteristic; Further grasped the monolithic integrated circuit to carry on many machine correspondences the principle; Also locks to the electron with the video frequency, the audio frequency control recuperates the module to have the certain degree to ford into.

通过对&智能可视门铃系统&课题的学习和设计，使我了解AT89C51单片机的特性；进一步的掌握了单片机进行多机通信的原理；也对电子锁和视频、音频的控制调理模块有一定程度的涉入。

Through to %26lsquo;the intelligent visible doorbell systems%26rsquo; the topic study and the design, makes me to understand the AT89C51 monolithic integrated circuit the characteristic; Further grasped the monolithic integrated circuit to carry on many machine correspondences the principle; Also locks to the electron with the video frequency, the audio frequency control recuperates the module to have the certain degree to ford into.

通过对%26ldquo；智能可视门铃系统%26rdquo；课题的学习和设计，使我了解AT89C51单片机的特性；进一步的掌握了单片机进行多机通信的原理；也对电子锁和视频、音频的控制调理模块有一定程度的涉入。

Along with the development of modern correspondence, the numeralturns increasingly daily life of permeating people, the people'sneed to various multi-media business increases increasingly, we areenjoying numeral to turn the convenience for bringing with fast,the satellite television, numerical television, various figuresmusic product is changing our lifes.

随着现代通信的发展，数字化日益渗透人们的日常生活，人们对各种多媒体业务的需求日益增长，我们正享受着数字化带来的方便和快捷，卫星电视、数字电视、各种数码音乐产品正改变着我们的生活。

As a personal communication an important component of the wireless LAN has set off a new wave of mobile computing, in the real social life and the future will be widely used.

作为个人通信的一个重要的组成部分，无线局域网已经掀起了移动计算的新浪潮，在现实及未来的社会生活中将得到广泛的应用。

Quantum cryptology is a new method for secret communications. Compared to the classical cryptography, the greatest advantages of quantum cryptography are provable security and detectives; this is because the security of quantum cryptography is ensured by quantum no-cloning and Heisenberg's uncertainty principle that instead of relying on some complex mathematical problems.

量子密码技术是一种实现保密通信的新方法，它比较于经典密码的最大优势是具有可证明安全性和可检测性，这是因为量子密码的安全性是由量子物理学中量子不可克隆性和Heisenburg测不准原理来保证的，而不是依靠某些难解的数学问题。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。