What Is WiFi?
A wireless network uses radio waves, just like cell phones, televisions and radios do. In fact, communication across a wireless network is a lot like two-way radio communication. Here's what happens:
- A computer's wireless adapter translates data into a radio signal and transmits it using an antenna.
- A wireless router receives the signal and decodes it. The router sends the information to the Internet using a physical, wired Ethernet connection.
The process also works in reverse, with the router receiving information from the Internet, translating it into a radio signal and sending it to the computer's wireless adapter.
The radios used for WiFi communication are very similar to the radios used for walkie-talkies, cell phones and other devices. They can transmit and receive radio waves, and they can convert 1s and 0s into radio waves and convert the radio waves back into 1s and 0s. But WiFi radios have a few notable differences from other radios:
- They transmit at frequencies of 2.4 GHz or 5 GHz. This frequency is considerably higher than the frequencies used for cell phones, walkie-talkies and televisions. The higher frequency allows the signal to carry more data.
- They use 802.11 networking standards, which come in several flavors: 802.11a transmits at 5 GHz and can move up to 54 megabits of data per second. It also uses orthogonal frequency-division multiplexing (OFDM), a more efficient coding technique that splits that radio signal into several sub-signals before they reach a receiver. This greatly reduces interference. 802.11b is the slowest and least expensive standard. For a while, its cost made it popular, but now it's becoming less common as faster standards become less expensive. 802.11b transmits in the 2.4 GHz frequency band of the radio spectrum. It can handle up to 11 megabits of data per second, and it uses complementary code keying (CCK) modulation to improve speeds. 802.11g transmits at 2.4 GHz like 802.11b, but it's a lot faster -- it can handle up to 54 megabits of data per second. 802.11g is faster because it uses the same OFDM coding as 802.11a. 802.11n is the newest standard that is widely available. This standard significantly improves speed and range. For instance, although 802.11g theoretically moves 54 megabits of data per second, it only achieves real-world speeds of about 24 megabits of data per second because of network congestion. 802.11n, however, reportedly can achieve speeds as high as 140 megabits per second. The standard is currently in draft form -- the Institute of Electrical and Electronics Engineers (IEEE) plans to formally ratify 802.11n by the end of 2009.
- Other 802.11 standards focus on specific applications of wireless networks, like wide area networks (WANs) inside vehicles or technology that lets you move from one wireless network to another seamlessly.
- WiFi radios can transmit on any of three frequency bands. Or, they can "frequency hop" rapidly between the different bands. Frequency hopping helps reduce interference and lets multiple devices use the same wireless connection simultaneously.
As long as they all have wireless adapters, several devices can use one router to connect to the Internet. This connection is convenient, virtually invisible and fairly reliable; however, if the router fails or if too many people try to use high-bandwidth applications at the same time, users can experience interference or lose their connections.
Other names and other wireless network standards
You may be wondering why people refer to WiFi as 802.11 networking. The 802.11 designation comes from the IEEE. The IEEE sets standards for a range of technological protocols, and it uses a numbering system to classify these standards.
WiMax, also known as 802.16, looks to combine the benefits of broadband and wireless. WiMax will provide high-speed wireless Internet over very long distances and will most likely provide access to large areas such as cities.
Wireless Standards
Wireless networking uses a range of standards -- the rules that routers and receivers use to communicate with each other. Most common are:
- 802.11a - 54 Mbps data rate in the 5 GHz band of the radio spectrum
- 802.11b - 11 Mbps, 2.4 GHz
- 802.11g - 54 Mbps, 2.4 GHz
Faster Wireless
Most home wireless networks use 802.11g wireless networking, which transmits data at 2.4 GHz with a speed of 54 megabits. A newer wireless standard is 802.11n, which is faster and has a longer range than 802.11g.
Wireless Networks
The easiest, least expensive way to connect the computers in your home is to use a wireless network, which uses radio waves instead of wires. The absence of physical wires makes this kind of network very flexible. For example, you can move a laptop from room to room without fiddling with network cables and without losing your connection. The downside is that wireless connections are generally slower than Ethernet connections and they are less secure unless you take measures to protect your network.
If you want to build a wireless network, you'll need a wireless router. Signals from a wireless router extend about 100 feet (30.5 meters) in all directions, but walls can interrupt the signal. Depending on the size and shape of your home and the range of the router, you may need to purchase a range extender or repeater to get enough coverage.
You'll also need a wireless adapter in each computer you plan to connect to the network. You can add printers and other devices to the network as well. Some new models have built-in wireless communication capabilities, and you can use a wireless Ethernet bridge to add wireless capabilities to devices that don't. Any devices that use the Bluetooth standard can also connect easily to each other within a range of about 10 meters (32 feet), and most computers, printers, cell phones, home entertainment systems and other gadgets come installed with the technology.
If you decide to build a wireless network, you'll need to take steps to protect it -- you don't want your neighbors hitchhiking on your wireless signal. Wireless security options include:
- Wired Equivalency Privacy (WEP)
- WiFi Protected Access (WPA)
- Media Access Control (MAC) address filtering
You can choose which method (or combination of methods) you want to use when you set up your wireless router. The IEEE has approved each of these security standards, but studies have proven that WEP can be broken into very easily. If you use WEP, you may consider adding Temporal Key Integrity Protocol (TKIP) to your operating system. TKIP is a wrapper with backward compatibility, which means you can add it to your existing security option without interfering with its activity. Think of it like wrapping a bandage around a cut finger -- the bandage protects the finger without preventing it from carrying out its normal functions.
- 802.11e - 54 Mbps, 2.4 GHz, with quality of service (QoS) protocols, which should improve VoIP and streaming media quality
A separate standard, 802.16 (or WiMAX), transmits at 70 Mbps and has a range of up to 30 miles. It can operate in licensed or unlicensed bands of the spectrum from 2-6 GHz. WiMAX typically links multiple 802.11 networks or sends Internet data over long distances.