网络与通信(chap3-WirelessNetworks)

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无线通信与网络技术

第三代蜂窝移动通信（3G）
提供高速数据传输服务，支持视频通话和移动互联网应用。
蜂窝移动通信系统组成
移动台（MS）：包括移动终端设备和用户识别模块（SIM卡），用于接入蜂窝移动通信网络。
移动交换中心（MSC）：负责处理呼叫和移动性管理，实现不同基站之间的通信。
基台（BS）：即基站，负责与移动台进行无线通信，并将信号传输到移动交换中心（MSC）。
中。
蓝牙技术还支持点对点和多点通信，可实现设备间的互联和互操
作。
ZigBee技术
ZigBee技术是一种基于IEEE 802.15.4标准的低功耗局域网协议，适用于短距离、低速率、低
功耗的无线通信场景。
ZigBee技术具有自组织、自愈能力强、安全性高等特点，广泛应用于智能家居、工业自动化、农
无线通信传输技术
01
02
03
04
模拟传输技术
早期无线通信主要采用模拟信号进行传输，如调幅、调频等
。
数字传输技术
现代无线通信主要采用数字信号进行传输，包括基带传输和
频带传输两种方式。
调制与解调技术
将原始信号转换为适合在无线信道中传输的形式，以及将接收到的信号还原为原始形式。
多址接入技术
允许多个用户同时使用同一无线信道进行通信，如FDMA、
工业和交通领域
实现设备监控、数据采集和远程控制等功能，提高生产效率和交通安全性。
军事和应急通信
在无线基础设施受损或无法覆盖的地区，提供快速、可靠的
通信支持。
03
无线局域网技术
无线局域网基本原理
利用无线通信技术
通过无线电波或红外线等无线传输介质进行数据传输。

【软考网络工程师教程-成功笔记】第5章无线通信网

【软考网络工程师教程-成功笔记】第5章无线通信网无线通信网包括面包语音通信的移动电话系统以及面向数据传输的无线局域网和无线广域网。

5.1 移动通信移动是最方便的个人通信工具。

从第一代（1G）到第三代（3G）移动通信系统都是针对语音通信设计的，只有4G才能与Internet无缝的集成。

5.1.1蜂窝通信系统1978年，美国贝尔实验室开发了高级移动电话系统（AMPS），采用模拟制式的频分双工（FDD）技术，用一对频率分别提供上行和下行信道。

AMPS采用蜂窝技术解决了公用移动通信系统所面临的大容量要求与频谱资源限制的矛盾。

蜂窝系统把一个地理区域划分成若干个称为蜂窝的小区（cell），因此移动电话也叫做蜂窝电话（Cellular Phone）。

在模拟移动电话系统中，一个话音连接要占用一个单独的频率。

如果把通信网络覆盖的地区划分成一个一个的小区，则在不同小区之间就可以实现频率复用。

在图5-1中，一个基站覆盖的小区用一个字母来代表，在一个小区内可以用一组频率一组用户进行通话。

相邻小区不能使用相同的通信频率，同一字母（例如A）代表的小区可以使用同样的通信频率。

从图中可以看出，使用同样频率的小区之间有两个频率不同的小区作为分隔，要增加频率的复用程序，可以把小区划分的更小，这样一来，有限的频率资源就可以容纳更多的用户通话了。

5.1.2 第二代移动通信系统第二代移动通信系统是数字蜂窝电话，我国采用有GSM系统和CDMA系统。

1.全球移动通信系统GSMGSM系统工作在900~1800MHz频段，无线接口采用TDMA技术，提供语音和数据业务。

图5-2中的每一行表示一个宽带为200Khz单工信道，GSM系统有124对这样的单工信道（上行链路890~915MHz），每一个信道采用时分多路（TDMA）方式可支持8个用户会话，在一个蜂窝小区同时通话的用户数为124*8=992。

2.码分多址技术美国高通公司的第二代数字蜂窝移动通信系统工作在800MHz频段，采用码分多址（CDMA）技术提供话音和数据业务。

Wireless Networks

Wireless NetworksWireless networks have become an integral part of our daily lives, providing us with the ability to connect to the internet from virtually anywhere. They have transformed the way we communicate, work, and access information, making it easier than ever to stay connected. In this essay, we will explore the various aspects of wireless networks, including their history, types, advantages, disadvantages, and future prospects.The history of wireless networks can be traced back to the late 19th century when Guglielmo Marconi demonstrated the first wireless telegraphy system. However, it wasn't until the 1970s that the concept of a wireless local area network (WLAN) was introduced. The first commercial wireless network, known as the ARPANET, was developed in the United States in the late 1960s and early 1970s. This networklaid the foundation for the development of the internet as we know it today.There are several types of wireless networks, each with its own unique characteristics and uses. The most common types include:1. Wi-Fi: This is the most widely used wireless network technology, allowing users to connect to the internet through a wireless access point. Wi-Fi networks are commonly found in homes, offices, and public spaces such as coffee shops and airports.2. Cellular networks: These networks use cellular technology to provide mobile internet access to users. They are commonly referred to as 2G, 3G, 4G, and 5G networks, with each generation offering faster speeds and improved performance.3. Bluetooth: This is a short-range wireless technology that allows devices to communicate with each other over a distance of up to 10 meters. It is commonly used for connecting peripherals such as keyboards, mice, and headphones to computers and smartphones.4. Zigbee: This is a low-power, low-data-rate wireless technology that is commonly used for home automation and IoT (Internet of Things) applications.5. Satellite networks: These networks use satellites to provide internet access to remote or underserved areas. They are particularly useful in rural or developing regions where traditional wired or wireless networks are not available.One of the main advantages of wireless networks is their convenience and flexibility. They allow users to connect to the internet from virtually anywhere, without the need for physical cables or wires. This has made it easier for people to work remotely, collaborate with others, and access information on the go.Another advantage of wireless networks is their ability to support a large number of users simultaneously. This makes them ideal for use in crowded public spaces such as airports, stadiums, and convention centers, where many people need to connect to the internet at the same time.However, wireless networks also have their disadvantages. One of the main issues is their vulnerability to security threats. Since wireless signals can be intercepted by anyone within range, it is important to use strong encryption and security measures to protect sensitive data.Another disadvantage of wireless networks is their susceptibility to interference. Wireless signals can be disrupted by physical obstacles such as walls and buildings, as well as by other electronic devices that emit electromagnetic radiation. This can result in slow or unreliable connections, particularly in densely populated urban areas.Looking to the future, it is clear that wireless networks will continue to play a crucial role in our increasingly connected world. As technology advances, we can expect to see even faster and more reliable wireless networks, with the potential to support new applications and services that we can't even imagine yet.In conclusion, wireless networks have revolutionized the way we connect to the internet and access information. They offer numerous advantages, such as convenience, flexibility, and the ability to support a large number of users. However, they also have their disadvantages, including security vulnerabilities and susceptibility to interference. As we look to the future, it is clear that wireless networks will continue to evolve and play an increasingly important role in our lives.。

Cisco Networking Academy 9781587133299 交换网络和通信技术说明

Trades & Technology9781587133299 • ©2014768pp • Hardback • £48.99eBook: 9780133476422 • £32.99Switched Networks course in the Cisco® NetworkingAcademy® CCNA® Routing and Switching curriculum.This course describes the architecture, components,and operations of a converged switched network.You will learn about the hierarchical networkdesign model and how to configure a switch forbasic and advanced functionality. By the end of thiscourse, you will be able to troubleshoot and resolvecommon issues with Virtual LANs and inter-VLANrouting in a converged network. You will also developthe knowledge and skills needed to implement aWLAN in a small-to-medium network.CCNP Routing andSwitching v2.0 Official CertGuide LibraryKevin Wallace, David Hucaby,Cristian Matei & Wendell Odom9781587206634 • ©20152050pp • Hardback • £121.50Course: CCNP (Cisco Certified NetworkProfessional)The new edition of bestselling CCNP Routing andSwitching Official Cert Library is a comprehensivereview and practice package for the latest CCNPRouting and Switching exams. The three bookscontained in this package, CCNP ROUTE Official CertGuide (9781587205590), CCNP SWITCH Official CertGuide (9781587205606), and CCNP TSHOOT OfficialCert Guide (9781587205613), present completereviews and a more challenging and realisticpreparation experience. The books will be fullyupdated to cover the latest CCNP exam topics. CCDA 200-310 Official CertGuide, 5eAnthony Bruno & Steve Jordan9781587144547 • ©2016750pp • Hardback • £44.93eBook: 9780134305592 • £46.07Course: CCDA (Cisco Certified Design Associate)CCDA Official Cert Guide is a comprehensive self-study tool for preparing for the new DESGN exam.Complete coverage of all exam topics as posted onthe exam topic blueprint ensures students will arriveat a thorough understanding of what they need tomaster to succeed on the exam.Designing for Cisco NetworkService Architectures(ARCH) FoundationLearning Guide: CCDPARCH 300-320, 4eMarwan Al-shawi & Andre Laurent9781587144622 • ©2017944pp • Hardback • £58.99eBook: 9780134424583 • £37.00Course: CCDP (Cisco Certified Design Professional)As a Foundation Learning Guide, this book fullyreflects the content of the newest Cisco CCDP ARCHcourse. Real-world scenarios illustrate key concepts;chapter learning objectives and summaries helpfocus study; and review questions help readersassess their knowledge.& Terry Vinson9781587144929 • ©20141400pp • Hardback • £90.87the new CCIE v5.0 exam. Included are Cisco CCIE Routing and Switching v5.0 Official Cert Guide,Volume 1 (9781587143960), and Cisco CCIE Routing and Switching v5.0 Official Cert Guide, Volume 2 (9781587144912).CCNA Wireless 200-355 Official Cert GuideDavid Hucaby9781587144578 • ©2016608pp • Hardback • £37.77 eBook: 9780134307169 • £25.00Course: CCNA 1 Exploration Network Fundamentals(Cisco Networking Academy Program)The CCNA Wireless Official Cert Guide is acomprehensive self-study tool for preparing for the latest CCNA Wireless exam. Complete coverage of all exam topics as posted on the exam topic blueprint ensures readers will arrive at a thorough understanding of what they need to master to succeed on the exam. The book follows a logical organization of the CCNA Wireless exam objectives. Material is presented in a concise manner,focusing on increasing readers’ retention and recall of exam topics.Routing Protocols Companion GuideCisco Networking Academy9781587133237 • ©2014792pp • Hardback • £48.99 eBook: 9780133476293 • £32.99Course: CCNA 2 Exploration Routing Protocols andConcepts (Cisco Networking Academy Program)This is the only Cisco-authorized companion guide to the official Cisco Networking Academy Routing Protocols course for the new CCNA Routing and Switching curriculum. An indispensable resource for hundreds of thousands of Cisco Networking Academy students worldwide, this portable desk reference is ideal for anytime/anywhere take-home study and reference. Fully aligned to the online course chapters, it offers additional book-based pedagogy to reinforce key concepts, enhance student comprehension, and promote retention.Routing and Switching Essentials v6 Companion GuideCisco Networking Academy9781587134289 • ©2017640pp • Hardback • £55.15 eBook: 9780134669649 • £56.33Course: CCNA 1 Discovery: Home and SmallBusiness NetworkingRouting and Switching Essentials v6 CompanionGuide is the official supplemental textbook for the Routing and Switching Essentials course in the Cisco Networking Academy CCNA Routing and Switching curriculum. This course describes the architecture, components, and operations of routers and switches in a small network.Certification Exam, 2eAllan Johnson9781587204531 • ©2013368pp • Paperback • £27.99eBook: 9780133517729 • £16.99preparation using a variety of Foundational andSupplemental study resources. The book breaksdown key exam topics into 31 daily review sessionsusing short summaries, lists, tables, examples, andgraphics. A Study Resources section provides a quickreference for locating more in-depth treatment ofa day’s topics within the relevant Foundational andSupplemental resources.Scaling Networks v6Companion GuideCisco Networking Academy9781587134340 • ©2017672pp • Hardback • £53.99eBook: 9780134760902 • £56.33Course: CCNA 3 Discovery: Introduction to Routingand Switching in the EnterpriseScaling Networks Companion Guide is the officialsupplemental textbook for the Scaling Networkscourse in the Cisco® CCNA® Academy®. This coursedescribes the architecture, components, andoperations of routers and switches in a large andcomplex network. You will learn how to configurerouters and switches for advanced functionality. Bythe end of this course, you will be able to configureand troubleshoot routers and switches and resolvecommon issues with OSPF, EIGRP, STP, and VTP inboth IPv4 and IPv6 networks. You will also developthe knowledge and skills needed to implement DHCPand DNS operations in a network. Connecting Networks v6Companion GuideCisco Networking Academy9781587134326 • ©2017512pp • Hardback • £53.99eBook: 9780134760872 • £56.33Course: CCNA 4 Discovery: Designing andSupporting Computer NetworksThis Companion Guide (CG) is the full-featuredtextbook that supports the Cisco NetworkingAcademy course. The chapter content aligns 1:1 tothe online course topics, but not necessarily word-for-word. The features of the textbook are designedto reinforce the course material and enhancestudent comprehension and retention of the coursetopics. As a portable learning tool, the CG is intendedto help students focus on important concepts,organize their study time for quizzes and exams, andserve as a future reference resource.CCNA Security (210-260)Portable Command Guide,2eBob Vachon9781587205750 • ©2016352pp • Paperback • £25.99eBook: 9780134307435 • £16.99Course: Cisco CertificationWhether you are studying for the Cisco IOS NetworkSecurity certification exam (Currently referred toas IINS v3) or just want to have a quick referenceguide to practical security commands, this bookwill be useful to keep on hand. This book takes apractical but detailed approach to security controlsof IOS devices as well as a functional introduction tothe ASA adaptive security appliances. The securitycountermeasures covered include device protectionfor routers and switches, identity-aware accesscontrol, firewall services, IPS deployment, Layer 2attack mitigation, and VPN technologies.1064pp • Paperback • £55.99eBook: 9781447930174 • £44.99engineers and systems designers wishing tounderstand new and future developments inthe field.Top-Down Network Design,3ePriscilla Oppenheimer9781587202834 • ©2010600pp • Hardback • £56.99eBook: 9781587140006 • £38.99Course: Local Area NetworksThis text presents a systematic, fully practicalapproach to designing network’s It covers all facetsof enterprise network design and all elementsof modern enterprise networks. The authors’innovative top-down approach starts by focusing onapplications and user requirements, and only thenturns to technology selection. Readers will discoverhow to systematically analyze business and technicalrequirements, and then select topologies andtechnologies that reflect this analysis.Network ManagementFundamentalsAlexander Clemm9781587201370 • ©2006552pp • Paperback • £47.99eBook: 9781587052804 • £29.99Course: Network ManagementNetwork management is an essential factor insuccessfully operating a network. As a companybecomes increasingly dependent on networkingservices, keeping those services running issynonymous with keeping the business running.Network Management Fundamentals providesyou with an accessible overview of networkmanagement covering management not just ofnetworks themselves but also of services runningover those networks.IPv6 Fundamentals: AStraightforward Approachto Understanding IPv6, 2eRick Graziani9781587144776 • ©2017688pp • Paperback • £43.99eBook: 9780134670591 • £46.07Course: Network ProtocolsTo support future business continuity, growth, andinnovation, organizations must transition to IPv6, thenext generation protocol for defining how computerscommunicate over networks. IPv6 Fundamentalsprovides a thorough yet easy-to-understandintroduction to the new knowledge and skills networkstudents need to learn in order to deploy and manageIPv6 networks. The Second Edition includes evenmore examples as the concepts are explained. TCP/IP Illustrated, Volume1: The Protocols, 2eKevin R. Fall & W. Richard Stevens9780321336316 • ©20111056pp • Hardback • £51.99eBook: 9780132808170 • £34.99Course: TCP/IPMore than 162,000 networking professionalshave relied on this book to gain the detailedunderstanding of TCP/IP they need to be effective.Now, the world’s leading TCP/IP best-seller has beenthoroughly updated to reflect a new generationof TCP/IP-based networking technologies. TCP/IP Illustrated, Volume 1, Second Edition doesn’t justdescribe protocols: it enables readers to observehow these protocols operate under differentconditions, using publicly available tools, andexplains why key design decisions were made.9781292154855 • ©2016448pp • Paperback • £51.99hackers, and electronic fraud, organizations andindividuals are constantly at risk of having theirprivate information compromised. This creates aheightened need to protect data and resourcesfrom disclosure, guarantee their authenticity, andsafeguard systems from network-based attacks. Computer Networks andInternets, 6eDouglas Comer9781292061177 • ©2015672pp • Paperback • £57.99eBook: 9781292061825 • £46.99Course: Networking – IntroLeading networking authority Douglas Comerpresents a wide-ranging, self-contained tour of theconcepts, principles, and technologies that enabletoday’s Internet to support applications rangingfrom web browsing to telephony and multimedia.Comer begins by illuminating the applicationsand facilities offered by today’s Internet. Next, hesystematically introduces the underlying networktechnologies and protocols that make thempossible. With these concepts and technologiesestablished, he introduces several of the mostimportant contemporary issues faced by networkimplementers and managers, including quality ofservice, Internet telephony, multimedia, networksecurity, and network management. Navigating NetworkComplexity: Next-generation routing withSDN, service virtualization,and service chainingRuss White & Jeff (Evgeny) Tantsura9780133989359 • ©2015320pp • Paperback • £43.99eBook: 9780133988079 • £29.99Course: Networking – AdvancedNavigating Network Complexity is the firstcomprehensive guide to managing the deploymentand operational complexity associated with today’slarge scale networks. From start to finish, this bookhelps network professionals get past the hypeassociated with SDN, NFV, and other new controlplanes, assess their true impact, and gain more oftheir benefits with fewer problems.TelecommunicationsTechnologies ReferenceBrad Dunsmore & Toby Skandier9781587050367 • ©2002610pp • Hardback • £38.99Course: TelecommunicationsTelecommunications Technologies Reference offers acomplete reference for your students to technologieskey to the telecommunications industry. While manypublished references address physical mediumsuch as DDS, ISDN, and T1, far fewer explain howtheir international counterparts work. It is rare tofind a book that covers both North American andinternational telecommunications technologies.608pp • Paperback • £54.99eBook: 9781292108728 • £43.99friendly parts, it presents a clear and comprehensiveoverview of the field of wireless communications. Forthose who are new to the topic, the book explainsbasic principles and fundamental topics concerningthe technology and architecture of the field. Mobile Communications, 2eJochen Schiller9780321123817 • ©2003520pp • Paperback • £54.99Course: Mobile CommunicationsThis text is a successful introduction to the topicof mobile communications. It provides a thoroughgrounding in the field of mobile communications,using a wide range of examples, combined withstrong pedagogy to allow its use in high level coursesand for self study.。

教材WirelessCommunicationsandNetworks-中国科学技术大学

课程教学目的和基本要求
无线互连技术是目前及未来通信网络技术的研发热点。本课程以无线通信网络为主题，以无线通信与网络的技术和标准为重点，使学生全面理解无线网络基本知识、无线通信与连网的原理、技术和标准。教学目标是拓展学生学科知识的宽度、深度，为从事相关工作打下坚实的基础。
课程简介
本课程侧重于无线通信网络的关键技术，主要内容包括无线通信技术、无线局域网、无线广域网络、移动自组织网络及新型无线网络、无线网络安全等。课程主要讲授各种无线通信网络环境和协议的基本概念、原理，结合典型的应用场景、通信网络产品和案例深入剖析，使学生能够理解并掌握无线通信网络领域的前沿知识。
无线通信与网络
Wireless Communcations & Networks
中国科技大学软件学院
School of Software Engineering University of Science and Technology of China Fall 2008
授课教师
主讲教师：张信明 (博士、副教授) 联系方式： [1]email: xinming@ [2]Tel: 3602446 [3]办公室：东区新科研楼A区-407 [4]通讯地址：中国科学技术大学计算机系，邮编230027
Our Publication List on Wireless Networks(1)

[1]高雪梅,张信明,史栋,邹丰富. 移动Ad hoc网络模糊逻辑移动预测路由算法.软件学报(已录用). [2]张信明,曾依灵,干国政，陈国良.用遗传算法寻找OLSR协议的最小MPR集.软件学报,2006,17(04).EI06259948901. [3]谢飞,张信明,郭嘉丰,陈国良.延迟主导的自适应移动Ad hoc网络路由协议. 软件学报,2005,16(09).EI05449453433. [4]郭嘉丰,张信明,谢飞,陈国良.基于节点空闲度的自适应移动Ad hoc网络路由协议.软件学报,2005,16(05). EI05279197466. [5]Vincent Wenchen Zheng, Xinming Zhang, Daoke Liu, Dan Keun Sung . A Joint Power Control, Link Scheduling and Rate Control Algorithm for Wireless Ad hoc Networks . IEEE Wireless Communications & Networking Conference (WCNC), Hong Kong, March 2007. EI074810946092. [6]Xiaohai Wei, Guoliang Chen, Yingyu Wan, Xinming Zhang . Longest Lifetime Path in Mobile Ad Hoc Networks.软件学报,2006,17(03).EI06219897352. [7]Xiang Yu, Xinming Zhang, Can Que, Qiong Liu. A Practical Low Interference Topology Control for Mobile Ad hoc Networks . The Sixth International Conference on Networking, April 2007. EI074110862330. [8]Pengxi Liu, Xinming Zhang, Shuang Tian, Zhiwei Zhao, Peng Sun. A Novel Virtual Anchor Node-based Localization Algorithm for Wireless Sensor Networks . The Sixth International Conference on Networking, April 2007. EI074110860262. [9]Dong Shi, Xinming Zhang, Xuemei Gao, Wenbo Zhu, Fengfu Zou. A Link Reliability-aware Route Maintenance Mechanism for Mobile Ad hoc Networks . The Sixth International Conference on Networking, April 2007. EI074110860261.

第5章网络与通信

精品课件
2021/3/13
最初是由美国联邦通信委员会(FCC)分配的无需许可证的无线电频段（功率不能超过1W）。在美国分为为工业（902~928MHz）、科学研究（2.42~2.4835GHz）和医疗（5.725~5.850GHz）三个频段。而在欧洲900MHz 的频段则有部份用于GSM通信，用于ISM的低频段为 868MHZ和433MHz。2.4GHz为各国共同的ISM频段。因此，无线局域网，蓝牙，ZigBee等无线网络，均可选择在2.4GHz频段上。
互联网/电信网是物联网的核心网络、平台和技术支持。互联网是一个很庞大的系统，它包括物理层、数据链路层、传输层、网络层和应用层。其核心技术就是数据交换。网络接入方式分为有线接入和无线接入，数据交换分为电路交换、报文交换和分组交换。
精品课件
2021/3/13
互联网的TCP/IP协议是网络层中的核心内容。为了让 Internet适应物联网大数据量和多终端的要求，业界正在发展一系列新技术。互联网中用IP地址对节点进行标识，而目前的IPv4受制于资源空间耗竭，已经无法提供更多的IP地址，所以IPv6以其近乎无限的地址空间将在物联网中发挥重大作用。IPv6的使用扫清了可接入网络的终端设备在数量上的限制。
精品课件
2021/3/13
4）具有很好的抗干扰能力，工作在ISM频段的无线电设备有很多种，如家用微波炉、无线局域网（WLAN）、 Home RF等产品，为了能很好地抵抗来自这些设备的干扰，蓝牙采用了跳频（Frequency Hopping）方式来扩展频谱（Spread Spectrum），将2.402～2.48GHz 频段分成79个频点，相邻频点间隔1MHz。蓝牙设备在某个频点发送数据之后，再跳到另一个频点发送，而频点的排列顺序则是伪随机的，每秒钟频率改变1600次，每个频率持续625μS。

计算机网络与通信的知识点总结

计算机网络与通信的知识点总结计算机网络与通信是现代信息技术的基础，它涉及到了许多重要的概念和技术。

本文将对计算机网络与通信的一些重要知识点进行总结，帮助读者更好地理解和应用这些概念。

一、计算机网络的基本概念1. 计算机网络的定义：计算机网络是指将分布在不同地理位置的计算机和其他设备通过通信线路互连起来，实现信息交换和资源共享的系统。

2. 网络拓扑结构：常见的网络拓扑结构包括总线型、环型、星型、树型和网状型等，每种结构都有其特点和适用场景。

3. 网络协议：网络协议是计算机网络中实现通信的规则和约定。

常见的网络协议有TCP/IP协议、HTTP协议、FTP协议等。

二、计算机网络的层次结构1. OSI参考模型：OSI参考模型是一种将计算机网络分为七层的抽象模型，包括物理层、数据链路层、网络层、传输层、会话层、表示层和应用层。

每一层都有不同的功能和责任。

2. TCP/IP模型：TCP/IP模型是实际应用最广泛的网络层次结构，它包括物理层、数据链路层、网络层、传输层和应用层。

三、网络通信的基本原理1. 数据传输方式：常见的数据传输方式有单工、半双工和全双工。

单工只能单向传输数据，半双工可以双向传输但不能同时进行，全双工可以同时进行双向传输。

2. 数据交换方式：数据交换方式包括电路交换、报文交换和分组交换。

电路交换在通信开始前需要建立一条专用的物理连接，报文交换将数据分成固定长度的报文进行传输，分组交换将数据分成较小的数据包进行传输。

3. 数据传输的可靠性：为了保证数据传输的可靠性，常用的方法有检错、重传和流量控制等。

四、常见的网络协议和技术1. IP协议：IP协议是互联网上最常用的网络协议之一，它负责将数据包从源主机传输到目标主机。

2. TCP协议：TCP协议是一种可靠的传输协议，它负责将数据分割成报文段，并通过网络将其传输到目标主机，然后再将其重新组装成完整的数据。

3. HTTP协议：HTTP协议是一种应用层协议，它定义了Web浏览器和Web服务器之间的通信规则，常用于传输超文本和其他资源。

无线通信与网络

译者序
译者序
近几年中，包括UWB、蓝牙、WLAN、WiMAX、Mobile-Fi、ZigBee等各种无线新技术的出现，随时、随地、随心所欲地连接到Internet，让络无处不在的梦想几乎触手可及。在企业、家庭内部，无线应用将彻底改变人们日常工作、生活的方式。随着802.11标准的发展，无线局域技术也已日臻成熟，而且其传输速率、通信距离也在不断增加，能够满足诸多场合的应用需求。除了组以外，无线络在下一步的发展中还可以结合自身的..
无线通信与网络
20xx年清华大学出版社出版的图书
01 内容简介
03 推荐
目录
02 译者序 04 作品目录
基本信息
《无线通信与络》是2005年10月1日清华大学出版社出版的图书，作者是斯托林斯，译者是何军。本书可作为通信和计算机专业本科生和研究生的教材或教学参考书，是从事无线通信和络方面研究的科研和工程技术人员的基础参考读物。
内容简介
内容简介
《无线通信与络》无线技术已成为电信和络界最激动人心的领域。移动使用的迅猛增长、各种卫星服务，以及现在的无线因特和无线局域正对电信和络产生巨大的改变。本书分为以下几个部分讨论了这一领域中的关键内容。 ●技术和体系结构：汇集了用来表征和区分无线通信和络的一些概念和知识，包括频带、信号编码技术、差错校验技术以及络体系结构等。 ●络类型：本书介绍了无线络的重要类型，包括卫星、蜂窝、固定无线接入和们的优点。 ●应用：在无线基础结构之上已经开发出了许多关键的技术和应用，特别是移动IP和无线Web接入。
作品目录
作品目录
第1章引言 1.1无线通信时代的到来 1.2蜂窝革命 1.3全球蜂窝络 1.4宽带 1.5未来趋势 1.6无线技术中的问题 1.7本书概要 1.8 Internet和Web资源第2章传输基础 2.1传输信息的信号

Communications and Networks

COMMUNICATIONS AND NETWORKS（通信和网络）COMMUNICATIONS（通信）Communications is the process of sharing data, programs, and information between two or more computers. Applications include e-mail, instant messaging, Internet telephones, and electronic commerce.译文：通信是在两台或更多计算机上共享数据、程序和信息的过程。

应用包括电子邮件、即时消息、因特网电话和电子商务。

Connectivity（连接）Connectivity is a concept related to using com-puter networks to link people and resources. You can link or connect to large computers and the Internet providing access to extensive informa-tion resources.译文：连接是一个与使用计算机网络联系人和资源相关的概念。

你可以链接或连接到大型计算机和因特网，提供访问广泛的信息资源。

The Wireless Revolution（无线革命）Mobile or wireless telephones have brought dra-matic changes in connectivity and communica-tions. These wireless devices are becoming widely used for computer communication.译文：移动电话或无线电话在连接和通信上已经带来戏剧性变化。

网络与通信chapMobileCellularSystems优质获奖课件

Received power must be sufficiently above the background noise for effective communication
Desirable to minimize power in the transmitted signal from the mobile
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反向链路旳功率控制
16
Traffic Engineering
Ideally, available channels would equal number of subscribers active at one time
In practice, not feasible to have capacity handle all possible load
本章简介全部蜂窝网络所需用到旳基本原理，考察已经被分为三代旳蜂窝技术和原则：
第一代是基于模拟旳，尽管仍在广泛使用，却已在逐渐淘汰中；
今日旳主流技术是数字式旳第二代系统；第三代高速数字式系统也已开始出现。
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Outline
Cellular Concept
Cellular Architecture Frequency Reuse
Handoff delay(越区切换时延 ) – distance the mobile moves from the point at which the handoff should occur to the point at which it does occur
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Handoff Strategies Used to Determine Instant of Handoff
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途径损耗旳Hata模型举例：

chap03 Communication Networks 无线网络通信英文课件

Observations of Figure 3.3
Some nodes connect only to other nodes (e.g., 5 and 7)
Some nodes connect to one or more stations Node-station links usually dedicated point-to-point
Subscribers - devices that attach to the network; mostly telephones
Subscriber line - link between subscriber and network
Also called subscriber loop or local loop
data
Circuit disconnect
Circuit is terminated Each node deallocates dedicated resources
Characteristics of Circuit Switching
Can be inefficient
Channel capacity dedicated for duration of connection Utilization not 100% Delay prior to signal transfer for establishment
packet header that includes control information
At each node en route, packet is received, stored briefly and passed to the next node

网络与通信技术PPT课件

数字微波通信
利用微波传输数字信号，具有传输容量大、抗干扰能力强、保密性好等优点，常用于移动通信和卫星通信。
无线通信技术
无线局域网（WLAN）
通过无线方式连学校、医院等场所。
VS
蓝牙通信
一种短距离无线通信技术，可以实现设备之间的数据传输和设备控制，如手机、耳机、打印机等设备之间的连接。
1990年代
2000年代至今
万维网的普及和发展，使得互联网成为人们获取信息、交流思想的重要平台。
移动互联网、物联网、云计算、大数据等新兴技术的发展和应用，进一步推动了网络与通信技术的进步和应用。
网络与通信技术的应用场景
社交网络
电子商务
通过社交媒体平台实现信息发布、分享和交流，
如微信、微博等。
详细描述
无线广域网主要用于实现移动设备的无线接入，如移动电话网络、卫星通信网络等。这种网络技术使得用户可以在任何地方都能接入网络，并且能够保持通信的连续性和稳定
性。
05 通信技术及其应用
有线通信技术
光纤通信
利用光波在光纤中传输信息，具有传输速度快、容量大、抗干扰能力强等优点，广泛应用于长距离通信和高速网络。
通信技术的应用场景
电信业务
提供电话、短信、数据传输等电信服务，满足人们的日常通信需
求。
物联网应用
实现设备之间的互联互通，如智能家居、智能交通、智能工业等领域。
云计算服务
提供云存储、云计算等服务，满足企业和个人对数据处理和存储的需求。
06 网络与通信安全
网络与通信安全威胁
01
02
03
04
详细描述
OSI参考模型为不同系统之间的通信提供了统一的模型，使得不同厂商和不同操作系统之间的网络通信变得可能。这七个层次各自承担着不同的功能，如应用层负责处理用户应用程序和网络之间的交互，传输层负责端到端的数据传输等。

chap3数据通信PPT资料61页

0100 1100 011
时钟
NRZ
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位同步
Ⅱ. 内同步法从自含时钟编码的发送数据中提取同步时钟的方法。
0100 1100 011
时钟
Manchester
差分 Manchester
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字符同步
（2）字符同步 (character synchronous)
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同步技术
（1）位同步（bit synchronous）接收端根据发送端发送数据的时钟频率与比特流的起始时刻，来校正自己的时钟频率与接收数据的起始时刻。
Ⅰ. 外同步法 Ⅱ. 内同步法
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位同步
Ⅰ. 外同步法发送端发送一路数据信号的同时，另外发送一路同步时钟信号。
第3章数据通信

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第 3 章数据通信
3.1 数据通信的基本概念 3.2 频带传输技术 3.3 基带传输技术 3.4 多路复用技术
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3.1 数据通信的概念
1. 信息、数据与信号（1）信息通信的目的是交换信息，信息的载体可以是数字、文字、语音、图形或图像。将这些数字、文字、语音、图形或图像放到计算机中进行处理时，需要将这些信息数字化。我们早已了解数字、文字、语音、图形或图像等信息在计算机表示的方式。以这样的思路，我们可以想象数据通信的内容是什么。
同步字符
1个字符
1个字符
1组字符
图3- 3 同步传输
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Ⅱ. 异步式异步通信

电子商务概论计算机网络通信及相关技术

• 计算机应用：EDI的条件； • 通信网络：EDI应用的基础； • 数据原则化：EDI的特性。
EDI应用系统
• 分类 • 功效
EDI数据解决 EDI网络通信
EDI服务中心
• EDI服务中心的构成及功效
1、公用EDI服务手段 2、通信接口 3、公共业务服务 4、EDI最后顾客系统
• EDI服务中心的实现
4.6EDI增值网络技术
EDI介绍
• 定义一：国际原则化组织ISO将EDI描述成“将贸易(商
业)或行政事务解决按照一种共认的原则变成构造化的事务解决或信息数据格式，从计算机到计算机的电子传输。
• 定义二：国际电信联合会, 将EDI定义为“从计算机到计
算机之间的构造化的事务数据交换”。
• 定义三：联合国原则化委员会及联合国贸易与发展委员会
EDI典型应用
• 美国新奥尔良港全港业务集成系统 • 英国和北爱尔兰的弗立克斯维托港的FCP80
系统
• 中国集装箱运输EDI示范工程
其它有关技术
• 网络数据库 • 数据仓库
面对主题、集成的、相对稳定的、反映历史变化
• 多媒体技术 • J2EE技术 • Web Service技术
互操作性、普遍性、易于使用、行业支持
高层合同
• 1）TCP和UDP • 2）FTP
4.3网站建设技术
• 定义网站 • 定义信息构造 • 定义网站内容 • 探索装饰风格 • 可视化设计 • 有关技术
有关技术问题
• 1）服务器类型 • 2）平台（操作系统） • 3）数据库
4.4移动通信系统及其演进
• 第二代移动通信的应用及技术特点 • 第三代移动通信的概念及重要技术 • 第二代向第三代的演进 • 中国TD-SCDMA技术及其进展 • GPRS：通用分组无线业务

无线通信与网络教程

无线通信与网络教程无线通信与网络是现代社会中不可或缺的一部分，它们使人们之间的联系更加紧密，信息的传递更加迅捷。

本文将探讨无线通信与网络的基本原理、发展历程以及应用。

一、无线通信的基本原理无线通信是通过无线电波或红外线等电磁波进行信息传递的一种方式。

它借助无线电设备将信息转化为无线电信号，然后通过无线电波在空间中传播，最后被接收设备解码成实际的信息。

无线通信的基本原理包括调制、编码、发送、接收和解码等步骤。

调制是将要传输的信息信号与载波进行合成。

调制的方式有多种，最常见的有调幅（AM）和调频（FM）调制。

编码是将合成的调制信号转化为数字信号，使其能够在传输过程中更稳定地传递。

发送是通过无线电设备将编码后的信号发送出去，这一步需要借助天线来辐射无线电波。

接收是指接收设备接收到发送设备发出的无线电波，并将其转化为电信号。

解码是将接收到的电信号还原为最初的信息信号。

二、无线通信的发展历程无线通信的发展历程可以追溯到19世纪末的无线电技术的初步研究，而真正的无线通信则起源于20世纪初的无线电通信。

无线通信技术的发展经历了多个重要的里程碑。

首先是无线电技术的发展。

无线电技术的出现使得无线通信成为可能，通过发射和接收无线电波实现了远距离的信息传递。

著名的无线电创始人马克士·奥尔顿尼（Marconi）和奥古斯特·贝尔（Bell）对无线电技术的发展做出了重要贡献。

随后是移动通信的兴起。

20世纪70年代末，蔡少芬（Hokeda）在日本研发出世界首款移动电话系统，从此开启了移动通信的新篇章。

接着，GSM（Global System for Mobile Communications，全球移动通信系统）的诞生进一步推动了移动通信的发展，人们可以随时随地进行电话通话。

再之后，无线网络的兴起进一步改变了人们的通信方式。

20世纪90年代后期，无线局域网（WLAN）开始商用，并迅速走进人们的生活。

随着技术的不断发展，现如今的无线网络已经成为人们使用最广泛的一种网络技术。

计算机网络与通信文档(DOC)武汉工程大学药物仿真实验

计算机网络与通信文档（DOC）武汉工程大学药物仿真实验进入21世纪，人类进入了网络信息化时代，从日常生活、学习到迷信研讨再到人们的行为和思想无不打下了信息时代的烙印。

借助无处不在的无线和有线网络，人们之间的沟通变得更方便、更快捷。

人们可以在网上交友、冲浪、旅游、购物、休闲文娱，可以享用即时通讯，接受远程教育，发行电子刊物，而电子银行、电子商务、网上图书馆的便利更是显而易见。

同时还有网络警察、网络部队时辰为人们维护网络次第，提供平安保证。

理想生活中存在的东西简直都能在网络上找到，因此越来越多的人们参与到网络运用的行列中。

依据著名的梅特卡尔菲定律〔Metcalfe’s Law〕，网络的价值将随着用户数的添加而按指数规律增长。

既然网络如此重要，与人们的生活又联络得如此严密，那么我们就有必要掌握好网络技术，并充沛应用它武装自我，迎接应战，为自己在当今网络信息社会中的立足和开展做好预备。

众所周知，从日常通讯运用的IP 、移动通讯设备、聊天工具QQ，到网络通讯新技术10G以太网、下一代网络〔NGN〕等都包括着信息技术的结晶，那么，该如何掌握网络开展意向，掌握并应用好目前盛行的网络技术呢？本章内容就将围绕这些效果展开。

本章重点•计算机网络的基本概念•完成〝三网合一〞的基础•无线网络•下一代Internet技术〔NGN〕的基本概念•计算机网络工程架构1.1 计算机网络技术概述计算机网络是计算机技术和通讯技术结合的产物，这种结合对计算机系统的组织方式发生了深远的影响。

为了完成数据交流和资源共享，就得将计算机互连起来，这样原来〝计算机中心〞的方式，即由一台计算机来处置整个组织中一切计算需求的模型，就被新的计算机互连模型取代。

这种互连模型就是计算机网络，它由资源子网和通讯子网组成。

人们通常所熟习的万维网不同于计算机网络，它是运转在Internet上的散布式系统。

在一个散布式系统〔distributed system〕中，一组独立的计算机展现给用户的是一个一致的全体。