Internet Architecture- Lecture 8

Internet Architecture Lecture 8:
How Wireless Connections and WiFi Work

Introduction
The wired world created a revolution of allowing people to connect to the Internet. Now the unwired world the ability to connect to the Internet wirelessly is bringing just as big a change.
The most popular way of connecting to the Internet wirelessly is via a family of technologies called 802.11 or WiFi. There are several different standards for 802.11, and they connect at different speeds, including 802.11b standard, which operates in the 2.4GHz spectrum and transfers data at a maximum rate of 11Mbps; the 802.11a standard, which operates in the 5GHz spectrum at 54Mbps; and the 802.11g standard, which operates in the 2.4GHz spectrum and transfers data at a maximum rate of 54Mbps. In addition, there are other emerging standards that transfer data at much higher rates, such as the 802.11n, which will transfer data at rates approximately ten times faster than 802.11g.

To connect to the Internet this way, an 802.11 card needs to be used in a computing device such as a laptop or palmtop computer, and it needs to connect to a nearby compatible wireless access point, most often called a router. These routers can be in a home or business. Increasingly there are also public access points, called hot spots, which allow you to connect to the Internet from public places such as coffee shops, hotels, and airports.
One problem with WiFi networks is that they can be vulnerable to snoopers and hackers, who can use a technique called war driving to get into the network.

There are a variety of other ways to connect wirelessly to the Internet as well, for example by using a satellite connection.
Satellite-access systems require that you use a modem. The modem is used to request information from the Internet, so when you send information through the Internet, it goes at normal modem speeds. However, that requested information is sent back to you at the high satellite transmission speeds, not the slower modem speeds. However, this means that if you re sending email, or transferring a file to someone via FTP, that information is sent at modem speeds, not satellite speeds.