蓝牙是一种支持设备短距离通信的无线电技术.doc

田奔辉 030841015 BluetoothBluetooth is a short-range communication support equipment, radio technology, research in recent years has become a hot topic and get a wide range of applicationsBluetooth technology uses high-speed frequency hopping and time division multiple access and other advanced technology, close to the most inexpensive digital equipment were several network link up.Bluetooth is an open, short-range wireless communications technology standards.It can be used in a relatively short distance, a variety of cable to replace the current program, through walls and other obstacles, through a unified short-range wireless link between various digital devices in a flexible, secure, low cost, minor meritsconsumption of voice and data communications.Bluetooth as a new short-range wireless communication technology has been widely used in various fields, which provides low-cost, low power, short distance wireless communication, constitute a fixed and mobile devices in the personal network communication environment, making close rangeall kinds of information devices to seamlessly share resources.Bluetooth devices should be interoperable, that is, any Bluetooth device should be able to achieve between the interconnection, including hardware and software.Protocol and protocol stack design The main principle is try to use a variety of high-level agreements, ensure that the existing agreements and the integration of Bluetooth technology and interoperability between various applications; take full advantage of the hardware and software compatible with Bluetooth specification system andBluetooth specification is open, to facilitate the development of new applications.SIG specific needs according to the protocol is divided into 4 layers: core agreement, RFCOMM cable replacement agreement, TCS call control protocol, and high-level agreements associated with the InternetSince Bluetooth is a radio communication standard as the media, third-party information may be easily intercepted, so the Bluetooth technology must take certain security mechanisms, particularly in the electronic trading applications.In order to provide security and to use the credibility of the information, the system must be in the application layer and link layer security measures.As market demand, more and more Bluetooth silicon will soon put into production.Hotels, post offices, golf courses, airports, retail malls, convention centers and commercial areas are equipped with Bluetooth technology.BluetoothSiG now has 2,400 member companies in 2015 will reach 1.4 billion Bluetooth chips, application machine almost 7 million units.The dream of swimming in the Bluetooth technology, youll find Bluetooth technology capable of anything.Little attention to the Internet for high-tech market, you will find Bluetooth technology from the birth of the day, has been placed on high expectations.I believe that with further development of science and technology, Bluetooth technology will be more widely used.蓝牙蓝牙是一种支持设备短距离通信的无线电技术，近年来已经成为研究的热点问题并获得了广泛的应用蓝牙技术使用高速跳频和时分多址等先进技术，在近距离内最廉价地将几台数字化设备呈网状链接起来。蓝牙是一个开放性的、短距离无线通信技术标准。它可以用来在较短距离内取代目前多种线缆连接方案，穿透墙壁等障碍，通过统一的短距离无线链路，在各种数字设备之间实现灵活、安全、低成本、小功耗的话音和数据通信。蓝牙作为一种新兴的短距离无线通信技术已经在各个领域得到广泛应用，它提供低成本、低功耗、近距离的无线通信，构成固定与移动设备通信环境中的个人网络，使得近距离内各种信息设备能够实现无缝资源共享。蓝牙设备应具有互操作性，即任何蓝牙设备之间都应能够实现互通互连，这包括硬件和软件。 设计协议和协议栈的主要原则是尽可能地利用现有各种高层协议，保证现有协议与蓝牙技术的融合以及各种应用之间的互通性；充分利用兼容蓝牙技术规范的软硬件系统和蓝牙技术规范的开放性，便于开发新的应用。具体的协议按SIG的需要分为4层：核心协、RFCOMM电缆替代协议、TCS电话控制协议以及与Internet相关的高层协议由于蓝牙通信标准是以无线电波作为媒介，第三方可能轻易截获信息，所以蓝牙技术必须采取一定的安全保护机制，尤其在电子交易应用时。为了提供使用的安全性和信息的可信度，系统必须在应用层和链路层提供安全措施。由于市场需求，越来越多的蓝牙硅片即将投入生产。旅馆、邮局、高尔夫球场、飞机场、零售商场、会议中心和商业领域都在采用蓝牙技术。BluetoothSiG现已拥有2400家会员公司，预计2015年蓝牙芯片将达14亿片，应用机器近7亿台。 畅游在蓝牙技术的梦想中，你会发现蓝牙技术无所不能。稍稍关注一下网络高科技市场，就会发现蓝牙技术从诞生的那一天起，就一直被人们寄予了极高的期望。相信随着科技的进一步发展，蓝牙技术必将获得更加广泛的应用。The Advantages of SDH The advantages of SDH are mainly reflected in the following: Lower network element costs: With a common standard, compatible equipment will be available from many vendors. In a highly competitive market prices will be vary attractive. Better network management: With better network management, operators will be able to more efficiently use the network and provide better service. The concept of TMN (Telecom Management Network) is under study by CCITT. Some TMN standards defining management system interfaces already exist.Faster provisioning: If new circuits can be software defined to use existing spare bandwidth then provisioning will be much faster. The only new connection needed will be from the customers premises to the nearest network access node.Better network utilization: With total control of routing customer circuits can be groomed or hubbed to make best use of network resources. Typically, all speech carrying circuits may be split from data circuits and routed for minimum delay. Data circuits, depending on the type, may be hubbed to a particular network DXC with the level of cross-connect needed. Better network survivability: With real-time rerouting possible, the networks Operation Support System will be able to take care of failure by reprogramming circuit paths. The built-in protection and reporting systems will automatically take care of simple transmission failures.Simpler handover: If all networks use equipment conforming to the same standard, the handover of circuits at the network node interface should be trouble free.Support of future services: Looking to the future, the SDH design will cater for new services like High Definition TV, Wide Area Network backbone networks, Broadband ISDN and new bandwidth-on-demand services. As the SDH operator will have total control of bandwidth allocation, any new service will be simple to operation.SDH的优势SDH的优势主要体现在以下:低成本的网络元素:普通标准、兼容的设备有利于很多厂商，在一个高度竞争的市场价格里将会变得更有吸引力。.更好的网络管理:以更好的网络管理、经营者能够更有效地利用网络,提供更好的服务。这个概念在国际电报电话咨询委员会研究TMN)。有些TMN标准接口定义管理系统已存在。设置:如果新电路的速度可以使用现有软件设置将多余的带宽就快得多。唯一的新连接需要将从客户的场所的网络接入节点。更好的网络利用：与客户可培训或套充分利用网络资源。一般来说 、 所有的言论可能 套 携带电路与一个特定的网络 DXC 现有水平的需要。更好的网络生存性:读改道,网络运营支持系统能够照顾失败重整电路的路径。内置的保护和报告系统会自动照顾简单的传输失败如果所有的网络的简单回归使用设备符合标准的回归,在网络节点接口电路应该免除麻烦未来的支持服务:展望未来,SDH设计迎合新的服务如高清晰度电视、大面积的主干网网络、宽带ISDN和新的宽带ISDN和新bandwidth-on-demand服务。作为SDH运营商将会完全控制带宽分配,任何新闻服务成为简单的操作。 TCP/IP Reference ModelThe TCP/IP model has four layers: the application layer, the transport layer, the internet layer, and the network access layer.The designers of TCP/IP felt that the higher-level protocols should include the session and presentation layer details. They simply created an application layer that handles high-level protocols, issues of representation, encoding, and dialog control. The TCP/IP combines all application-related issues into one layer, and ensures this data is properly packaged for the next layer. This is also referred to as the process layer.The transport layer typically deals with the issues of the reliability, flow control, and retransmission. One of its protocols, the transmission control protocol (TCP), provides excellent and flexible ways to create reliable, well-flowing, network communications. TCP is a connection-oriented protocol. It supports dialogues between source and destination while packaging application layer information into units called segments. Connection-oriented does not mean that a physical circuit exists between the communicating computers (that would be circuit switching). It does mean that Layer 4 segments must travel back and forth between two hosts to set up a logical connection before data can be sent. This layer is also sometimes called the host-to-host layer.The purpose of the internet layer is to send source packets from any network on the internetwork and have them arrive at the destination independent of the path and networks they took to get there. The specific protocol that governs this layer is called the Internet Protocol (IP). Best path determination and packet switching occur at this layer. Think of it in terms of the postal system. When you mail a letter, you do not know how it gets there (there are various possible routes), but you do care that it arrives.The name of this layer is broad and somewhat confusing. It also is called the host-to-network layer. Sometimes, its shown as two layers, as in the OSI model. The network access layer is concerne