A beginner’s guide to Wi Fi

What is Wi-Fi?

Wi-Fi is a technology that allows computers to share a network or internet connection wirelessly, without the need to connect to a commercial network.

It refers to several different wireless technologies with the technical name of IEEE 802.11. The most popular are 802.11b, 802.11a and 802.11g.

Wi-Fi networks usually consist of a router, which transmits the signal, and one or more adapters, which receive the signal and are usually attached to computers. More powerful transmitters, which cover a wider area, are known as base stations.

What’s special about it?

Firstly, Wi-Fi is low-cost. The equipment required to transmit and receive Wi-Fi signals is cheap. Most newer laptops have a WiFi adapter built-in, and routers cost as little as £40 (although £50 - £80 is more common).

Wi-Fi is also attractive - and cheap - because it operates in unregulated spectrum. This means that, unlike the frequencies over which mobile phone calls are transmitted, no licence is required to the WiFi frequencies. In effect, anyone who owns a WiFi router and adapter can set up their own miniature mobile data network, which can be used to send and receive emails, view web pages, and even make voice phone calls.

The downside is that WiFi can only transmit data over a short range - generally it can be measured in metres, although it can reach several kilometres where there are no physical obstacles.

The lack of regulation of the WiFi spectrum however is not consistent around the world, and also means that WiFi can be affected by other devices which operate in the same spectrum, such as garage remote controls.

How would I use it?

For home and business users, a Wi-Fi-enabled laptop means you can have internet access or be on a network connected to other nearby computers, without having to plug into any cables. It’s often relatively simple, from the user’s point of view, to connect to a wireless network. In the home, a router attached to a broadband modem will mean any computers in the house (and sometimes, in neighbouring houses) with wireless adapters will be able to access the internet and exchange data with other computers.

There are many commercial WiFi connectivity providers who operate wireless “hotspots” - usually for an hourly fee - in cafes, airports, hotels and other locations.

In some cities and towns, Wi-Fi users have linked their WiFi networks together to create free, community-based networks to share files and internet access and to play games. These efforts can extend the range of Wi-Fi by linking together.

Is it secure?

WiFi does have some security risks. This is partly because it is impossible to precisely limit how far the signal travels - meaning that theoretically, anyone walking down the street past your company or home could access the wireless network inside. However there are many ways of making Wi-Fi more secure, including products designed for securing corporate WiFi networks.

How can I use it to make a phone call?

There are several different ways. Users of voice-over-IP software such as Skype can connect a headset to their WiFi enabled laptop. As long as your laptop is logged on to a WiFi network with an internet connection, you can use your VoIP.

Wherever you can connect to a WiFi internet connection, you can probably use VoIP to make a phone call too.

There are some mobile phone handsets available that support WiFi and VoIP, allowing users to make cheap or free phone calls from any wireless hotspot.

What is WiMax - is it the same as WiFi?

No. The two are similar in that they are both wireless networking technologies, but WiMax (which is technically known as 802.16x) can travel as far as 30km and does not require “line of sight” between transmitters.

WiMax is however still in its very early stages compared with WiFi, and products that fully support the technology are not yet available.

What does it mean for telecoms companies?

WiFi and WiMax pose similar threats to the mobile telecoms industry that VoIP poses for fixed-line telecoms companies.

WiFi and particularly WiMax, used in conjunction with VoIP, could provide a far cheaper way of making phone calls from mobile locations, incurring little or no cost for the user beyond purchasing the equipment. As with fixed-line VoIP, however, telecommunications providers argue that phone calls made over such a system could be of poorer quality.

However WiFi equipment widely available today supports data speeds of up to 54mbps [megabits per second], while the fastest speed available from a 3G network is only up to 3mbps.

For several years, community-based WiFi networks have been running in many cities which offer free networking between participants with their own wireless adapters and transmitters. With enough participants running WiFi base stations, an entire city could be “covered” by a freely available wireless network.

Websites such as Community Wireless and Wireless Anarchy link to some of these local efforts. They have had varying levels of success, partly because of numerous technical barriers such as the “line of sight” requirement of WiFi which means trees, building and other geographical features can block the signal even between neighbouring houses.

Meanwhile Google is trialling a free, secure Wi-Fi network around Mountain View, California.

More Links:

Wi-Fi Alliance

WiMax Forum

Wikipedia - Wi-Fi