How Things Work: Wi-Fi

Credit: Michael Setzer/SciTech Editor Credit: Michael Setzer/SciTech Editor

You have probably used Wi-Fi at least once — on campus, at airports and coffee shops, or at home. Have you ever paused to think of how this super-convenient means of Internet connectivity actually works?

The Internet basically works through an exchange of data between devices, typically a client (the device that you are using) and a server, which processes your request for web pages and sends them to your device. Traditionally, these devices are connected through physical wiring. Modern Wi-Fi does away with the need for these wires by allowing the exchange of data wirelessly through radio waves.

Wi-Fi-enabled devices have an embedded chip called the wireless network adapter. This chip is responsible for generating radio waves corresponding to the requested web resource and transmitting them to the surrounding space. These waves are received by a router, which then forwards the request to the appropriate server through a wired connection. When the requested web page is received at the router, it transmits corresponding radio waves back to the device.

According to the website, the radio waves used in Wi-Fi transmissions are typically of high frequency — in the range of 2.4 to five gigahertz. The high frequency allows these waves to transmit much more data than ordinary radio waves, such as those used in cellphones, walkie-talkies, and televisions.

The routers that help establish Wi-Fi are the key components of wireless access points, popularly known as hotspots. According to the Encyclopedia Britannica, these hotspots typically have a range of less than 100 meters (330 feet), but can be limited to a room or house by radio-wave-blocking walls. They can also be extended to cover large areas, such as college campuses, through multiple overlapping access points, which reinforce the network. Incidentally, Carnegie Mellon was the first college campus to set up a campus-wide Wi-Fi network. This network, dubbed “Wireless Andrew,” was set up in 1993, long before Wi-Fi gained its current popularity.

Nowadays, laptops, smartphones, tablets, and other devices are manufactured with the embedded wireless network adapter chip. This enables the device to detect and connect to hotspots within range. Since this chip is universal, it allows the device to access a Wi-Fi hotspot anywhere in the world.

Setting up a Wi-Fi hotspot is easy. To set it up in a home or private space, all you need is a router that contains a wireless access point and either a digital subscriber line modem or a cable modem. These are widely available and can be easily installed at a convenient spot. Several compatible devices can simultaneously use a single router. In public spaces, cellular companies typically provide Wi-Fi, allowing their subscribers to access their respective hotspots.

Wi-Fi is very convenient, since hotspots are unobtrusive and relatively easy to set up compared to wired networks. However, wireless connection is not as secure as its wired counterpart: An intruder can tap into the Wi-Fi and intercept the communication to and from your device. Hence, it is typically advisable not to access sensitive data online while tapping the Wi-Fi in public places like airports or coffee shops.

Wi-Fi connections like the one at Carnegie Mellon and in most homes are password protected and locked to outsiders. Thus, they provide an additional layer of security, but only if a strong password is used. Carnegie Mellon provides the campus community with an even more secure Wi-Fi service called “CMU-SECURE,” which addresses various vulnerabilities typical in Wi-Fi networks. Thus, as frequently as possible, you should try to connect to “CMU-SECURE” while on campus.