什么叫蓝牙

什么叫蓝牙 What is Bluetooth? Bluetooth is a universal radio interface in the 2.45GHz frequency band that enables portable electronic devices to connect and communicate wirelessly via short-range, ad hoc networks. Each unit can simultaneously communicate with up to sever other units per piconet. Moreover, each unit can simultaneously belong to several piconets. What is Bluetooth Technology? Bluetooth technology which apart from Ericsson, has gained the support of Nokia, IBM, Toshiba, Intel and many other manufacturers. Eliminates the need for wires, cables and connectors for and between cordless or mobile phones, modems, headsets, PDAs, Computers, printers, projectors, local area networks, and so on, and paves the way for new and completely different devices and applications.Technology Characteristics—1Ms/s symbol rate exploits maximum available channel bandwidth. Fast frequency hopping avoids interference Adaptive output power minimizes interference Short data packets maximize capacity during interference Fast acknowledge allows low coding overhead for links CVSD(Continuous Variable Slope Delta Modulation)voice coding enables operation at high bit- error rates Flexible packet types supports wide application range Air interface tailored to minimize current consumption Basic Technical Information—Based upon a small, high performance integrated radio transceiver, each of which is allocated a unique 48-bit address derived from the IEEE 802.standard. Operate in the unrestricted 2.45GHz ISM free band, Which is available globally although slight variation of location and width of band apply. Range set at 10m to optimize for target market of mobile and business user Gross data rate 1Mbit/s with second generation plans to increase to 1Mbit/s One-to-one connections allow maximum data transfer rate of 721kbit/s (3 voice channels) Uses packet switching protocol based on frequency hop scheme with 1600 hops/s to enable high performance in noisy radio environments. The entire available frequency spectrum is used with 79 hops of 1Mhz bandwidth, analogous to the IEEE 802.11 standard. Low power consumption longevity for battery powered devices. During data transfer the maximum current drain is 30mA. However during pauses or at lower data rates will be lower. 蓝牙是一个频率为 2.45GHz 的通用无线电通信接口，它通过一个特殊的 网络可以在各种便携设备之间建立起无线连接并进行短程通信。在一个微微 网中，每个单元都能同时与其它各单元进行通信。而且，每一个单元可以同 时属于几个微微网。 什么是“蓝牙”技术? “蓝牙”技术最先是由爱立信开始研制的，现在已经得到了诺基亚 、 IBM、东芝、因特尔及许多其它相关制造厂家的支持。其目的是为了免除在 无绳电话或移动电话、调制解调器、头套式送/受话器、PDAs、计算机、打 印机、幻灯机、局域网等之间加装电线、电缆和连接器。而且，这种技术可 以延伸到那些完全不同的新设备和新应用中去。“蓝牙”的技术特性—以每秒 1M 个码元的字符速率传输，充分利用信道的最大有效带宽。 快速跳频避免干扰 可变的电源输出使干扰减小到最小 采用短数据包传输增强抗干扰能力 快速确认允许有附加低速率的编码被发送到链路上 连续可变斜率增量调制的语音编码可以在高误码率的情况下正常工作 灵活的分组类型支持多种应用 无线电空中接口使电耗达到最小"蓝牙"基本技术概要 每一个小型、高性能、集成的无线电收发机都有 IEEE 802 标准所规定的 一个唯一的 48 比特位地址 开放的 2.45GHz ISM 自由频段，全球都可以自由使用。 10 公里是最适于移动通信市场和商业用户的通信范围 总速率为 1Mbit/s，计划下一代产品将达到 2Mbit/s 点到点连接允许的最大数据传输速率为 721kbit/s 在无线电噪声环境里，利用基于每秒 1600 跳跳频表的分组交换协议可 以提高系统性能。以 1Mhz 带宽 79 跳来利用这个完整的可用频谱。这类似于 IEEE 802.11 标准。 低电能的消耗。在备用模式下仅需 0.3mA，这能延长那些使用电池供电 设备的寿命。数据传送时电流的最大消耗为 30mA.当暂停工作或低速传送数 据时电流消耗更低。 数字钱包 Digital Wallets A digital wallet is software that enables users to pay for goods on the Web. It holds credit-card numbers and other personal information such as a shipping address. Once entered, the data automatically populates order fields at merchant sites. When using a digital wallet, consumers don't need to fill out order forms on each site when they purchase an item because the information has already been stored and is automatically updated and entered into the order fields across merchant sites. Consumers also benefit when using digital wallets because their information is encrypted or protected by a private software code. And merchants benefit by receiving protection against fraud. Digital wallets are available to consumers free of charge, and they're fairly easy to obtain. For example, when a consumer makes a purchase at a merchant site that's set up to handle server-side digital wallets, he types his name and payment and shipping information into the merchant's own form. At the end of the purchase, one consumer is asked to sign up for a wallet of his choice by entering a user name and password for future purchases. Users can also acquire wallets at a wallet vendor's site. Although a wallet is free for consumers, vendors charge merchants for wallets. Digital wallets come in two main types: client-side and server- side. Within those divisions are wallets that work only on specific merchant sites and those that are merchant agnostic. Client-based digital wallets, the older of the two types, are falling by the wayside, according to analysts, because they require users to download and install software. A user downloads the wallet application and inputs payment and mailing information. At that point, the information is secured and encrypted on the user's hard drive. The user retains control of his credit card and personal information locally. With a server-based wallet, a user fills out his personal information, and a cookie is automatically downloaded. (A cookie is a text file that contains information about the user.)In this scenario, the consumer information resides on the server of a financial institution or a digital wallet vendor rather than on the user's PC. Server-side wallets provide assurance against merchant fraud because they use certificates to verify the identity of all parties. When a party makes a transaction, it presents its certificate to the other parties involved. A certificate is an attachment to an electronic message used to verify the identity of the party and to provide the receiver with the means to encode a reply. Furthermore, the cardholder's sensitive data is typically housed at a financial institution, so there's an extra sense of security because financial environments generally provide the highest degree of security. But even though wallets provide easy shopping online, adoption hasn't been widespread. Standards are pivotal to the success of digital wallets. 数字钱包是一种能使用户在 Web 网上支付货款的软件。它保存信用卡 号码和其它个人信息，如送货地址。数据一旦被输入，就自动转移到商家网 站的订货域。 使用数字钱包时，当消费者购买物品时，不需要填写每个站点上的订单， 因为信息已经存储了，并自动更新和进入到厂商站点的订货域。消费者使用 数字钱包时也能得到好处，因为他们的信息被加密了，即由私人软件代码加 以保护。商家也避免了受骗而得到保护，也从中获益。 对消费者来说，数字钱包是免费的，可以相当容易得到。例如，当消费 者在建立了处理服务器端数字钱包的商家网站上购买东西时，他把其名字、 付款额和送货信息输入到商家自己的表格中。在购买结束时，他被要求为他 选择的钱包签上用户名和今后购买时的口令。用户也能从钱包供应商的站点 上得到钱包。 虽然钱包对消费者是免费的，但(钱包)供应商对商家使用钱包要收费。 数字钱包分两大类型：客户端和服务器端(数字钱包)。在这些分类中是 那些只在某些商家网站上工作的钱包和那些商家不可知的钱包。 基于客户的数字钱包是两种钱包中较陈旧的一种，据分析人士称，这类 钱包已开始没人理睬了，因为它们要求用户下载和安装软件。用户下载钱包 的应用程序和输入付款额和邮寄信息。在这个意义上，信息是安全的，并在 用户的硬盘上进行了加密。用户在本地获得对其信用卡和个人信息的控制。 使用基于服务器的钱包时，用户填写其个人信息，并自动下载点心文件 (点心文件是一个包括了有关用户信息的文本文件)。在这种情况下，消费者 的信息驻留在金融机构或者数字钱包供应商的服务器上，而不是用户的 PC 机上。 服务器端钱包提供了针对商家欺骗的安全措施，因为它们使用证书，来 验明各方的身份。当一方进行交易时，它向涉及的另一方提交证书。证书附 着在电子报文上，用于验明另一方身份，并向接收方提供对回答进行编码的 手段。 另外，信用卡持有人的敏感信息一般保存在金融机构内，由于金融环境 通常提供最高等级的安全性，因而这又是一种额外的安全措施。 但是即使钱包提供了方便的网上购物，尚未被广泛采用。 标准化是数字钱包能否成功的关键。