1.1.3 Mobile Users移动用户
Mobile computers, such as notebook computers and personal digital assistants (PDAs), are one of the fastest-growing segments of the computer industry. Many owners of these computers have desktop machines back at the office and want to be connected to their home base even when away from home or en route. Since having a wired connection is impossible in cars and airplanes, there is a lot of interest in wireless networks. In this section we will briefly look at some of the uses of wireless networks.
移动计算机，比如，笔记本电脑和PDAs(personal digital assistants 个人数字助理)，是计算机产业中发展最快的部分之一。大多数这些计算机的所有者在办公室还有桌面电脑，他们希望不在家的时候能连上家里的机器，即使在远离家或在路上的时候也能连上。由于在汽车和飞机上，没有有线连接，这引起很多人对无线网络的兴趣。在这部分中，我们将简单来看看一些无线网络的使用。
Why would anyone want one? A common reason is the portable office. People on the road often want to use their portable electronic equipment to send and receive telephone calls, faxes, and electronic mail, surf the Web, access remote files, and log on to remote machines. And they want to do this from anywhere on land, sea, or air. For example, at computer conferences these days, the organizers often set up a wireless network in the conference area. Anyone with a notebook computer and a wireless modem can just turn the computer on and be connected to the Internet, as though the computer were plugged into a wired network. Similarly, some universities have installed wireless networks on campus so students can sit under the trees and consult the library's card catalog or read their e-mail.
Wireless networks are of great value to fleets of trucks, taxis, delivery vehicles, and repairpersons for keeping in contact with home. For example, in many cities, taxi drivers are independent businessmen, rather than being employees of a taxi company. In some of these cities, the taxis have a display the driver can see. When a customer calls up, a central dispatcher types in the pickup and destination points. This information is displayed on the drivers' displays and a beep sounds. The first driver to hit a button on the display gets the call.
Wireless networks are also important to the military. If you have to be able to fight a war anywhere on earth on short notice, counting on using the local networking infrastructure is probably not a good idea. It is better to bring your own.
Although wireless networking and mobile computing are often related, they are not identical, as Fig. 1-5 shows. Here we see a distinction between fixed wireless and mobile wireless. Even notebook computers are sometimes wired. For example, if a traveler plugs a notebook computer into the telephone jack in a hotel room, he has mobility without a wireless network.
尽管无线网络和移动计算机通常联系在一起，但是他们并不相同，如图1-5所示。这里我们来看看固定无线（fixed wireless）与移动无线（mobile wireless）之间的区别。甚至笔记本电脑有时也通过有限网络来实现移动性。比如，一个外出旅行的人在宾馆房间内把笔记本电脑插入电话线的插孔里，这样即使没有无限网络也可以实现移动工作。
Figure 1-5. Combinations of wireless networks and mobile computing.无线网络与移动计算机之间的组合
On the other hand, some wireless computers are not mobile. An important example is a company that owns an older building lacking network cabling, and which wants to connect its computers. Installing a wireless network may require little more than buying a small box with some electronics, unpacking it, and plugging it in. This solution may be far cheaper than having workmen put in cable ducts to wire the building.
posted on 2006-04-12 12:42 我的翻译博客
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