How Does Wireless Networking Work?

The secrets of the internet cafe

There was a time when the phrase wireless networking would have conjured an image of a businesswoman using her cell phone to make client contacts. But today, with seemingly every café and coffee shop a Wi-Fi hotspot, wireless networking has become part of our common language. A quick primer on the ins and outs of wireless networking can help explain how exactly you can check your email while drinking a latte.

What is wireless networking?

Wireless networking is a technology that enables two or more computers to share resources, hardware, and information via radio signals. This sharing takes place over a geographic area referred to as a wireless local area network, or WLAN. A standard WLAN covers an area of about 300 feet, and up to 1,000 feet outdoors.

There are two primary types of WLANs: ad-hoc and infrastructure.

In an ad-hoc WLAN, computers equipped with a WLAN adapter or network interface card communicate directly with any and all PCs on the WLAN. This is why an ad-hoc WLAN is also referred to as a peer-to-peer network.

In an infrastructure WLAN, the computers communicate with an access point that operates as a hub. The access point can then either transmit data packets back across the WLAN or connect the wireless LAN to a wired LAN. An access point is a radio transceiver with an antenna that can be mounted on a wall or ceiling.

So how do WLAN computers communicate?

Imagine that the computers on a WLAN all speak a certain language. This language is transmitted via radio frequencies, but there are still certain grammatical rules that must be followed. The standards that determine data transmission speeds and the radio frequencies used are set by the IEEE, or Institute of Electrical and Electronics Engineers.

The abbreviation used for these standards is IEEE 802.11. As the IEEE made changes to those standards, they added subsets like 802.11a and 802.11b.

Wi-Fi is a standard way to refer to IEEE 802.11b. Wi-Fi moves information at a maximum speed of about 11 Mbps, or megabytes per second. For comparison, a DVD processes about 1 megabyte of information per second. Wi-Fi transmits this information at 2.4 GHz, which is a short wave radio frequency.

Security

The obvious question is: if you're sending information across radio waves, can just anyone pick up that information? Adapters use a couple different signal protocols to prevent this.

Frequency-hopping spread spectrum (FHSS) sends part of each data packet across several adjacent radio frequencies one after the other. Interestingly, FHSS was patented in 1942 by actress Hedy Lamarr, known at the time as the most beautiful woman in films.

Direct-sequence spread spectrum (DSSS) multiplies the data being sent by adding white noise that can be deciphered on the receiving end, but not by scanners or radios.

Wireless Networking in the future

As the number of WLANs increase and computers with Wi-Fi capability become prevalent, municipalities are constructing citywide broadband wireless networks. Some of these are public-private partnerships that cover a downtown radius, while others are truly citywide.

The future of wireless networking will not be without controversy, however. After the damage of Hurricane Katrina, New Orleans mayor Ray Nagin announced that New Orleans would deploy the nation's first municipally owned wireless Internet service as a means to help the city rebuild. BellSouth, who had just launched its own wireless broadband service a month prior, responded to the perceived unfair competition by taking back the offer of a 250,000 square-foot building donated to the city.

More information on wireless networking