Posts Tagged ‘Wi-Fi’

Understanding Wi-Fi

Posted: September 20, 2010 in Wi-Fi
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The most common wireless networking technology is wireless fidelity, which is almost always shortened to Wi-Fi, and the generic Institute of Electrical and Electronics Engineers (IEEE) designation for this wireless networking

standard is 802.11. There are four main types—802.11a, 802.11b, 802.11g, and 802.11n—each of which has its own range and speed limits.

802.11b

The original 802.11 standard was published by the IEEE in 1997, but few people took it seriously because it was hobbled by a maximum transmission rate of just 2Mbps. By 1999, the IEEE had worked out not one but two new standards:

802.11a and 802.11b. The 802.11b standard became the more popular of the two. 802.11b upped the Wi-Fi data transmission rate to 11Mbps, which is just a bit faster than 10BASE-T, the original Ethernet standard, which has a maximum rate of 10Mbps. The indoor range of 802.11b is about 115 feet. 802.11b operates on the 2.4GHz radio frequency, which is an unregulated frequency often used by other consumer products such as microwave ovens, cordless telephones, and baby monitors. This keeps the price of 802.11b hardware down, but it can also cause interference problems when you attempt to access the network near another device that’s using the 2.4GHz frequency.

802.11a

The 802.11a standard was released at around the same time as the 802.11b standard. There are two key differences between these standards: 802.11a has a maximum transmission rate of 54Mbps, and it operates using the regulated 5.0GHz radio frequency band. This higher frequency band means that 802.11a devices don’t have the same interference problems as 802.11b devices, but it also means that 802.11a hardware is more expensive, offers a shorter range (about 75 feet), and has trouble penetrating solid surfaces such as walls. So, despite its impressive transmission speed, 802.11a just had too many negative factors against it, and 802.11b won the hearts of consumers and became the first true wireless networking standard.

802.11g

During the battle between 802.11a and 802.11b, it became clear that consumers and small businesses really wanted the best of both worlds. That is, they wanted a WLAN technology that was as fast and as interference free as 802.11a, but had the longer range and cheaper cost of 802.11b. Alas, “the best of both worlds” is a state

rarely achieved in the real world. However, the IEEE came close when it introduced the next version of the wireless networking standard in 2003: 802.11g. Like its 802.11a predecessor, 802.11g has a theoretical

maximum transmission rate of 54Mbps, and like 802.11b, 802.11g boasted an indoor range of about 115 feet and was cheap to manufacture. That cheapness came from its use of the 2.4GHz RF band, which means that 802.11g devices can suffer from interference from other nearby consumer devices that use the same frequency.

Despite the possibility of interference, 802.11g quickly became the most popular of the Wi-Fi standards, and almost all WLAN devices sold today support 802.11g.

802.11n

The IEEE is has a new wireless standard called 802.11n. 802.11n implements a technology called multiple-input multiple-output (MIMO) that uses multiple transmitters and receivers in each device. This enables multiple data streams on a single device, which will greatly improve WLAN performance. For example, using three transmitters and two receivers (the standard configuration), 802.11n promises a theoretical transmission speed of up to 248Mbps. It’s still not Gigabit Ethernet, but 802.11n devices could finally enable us to stream high-quality video over a wireless connection. 802.11n also promises to double the wireless range to about 230 feet. These are all impressive numbers, to be sure, and even if the real-world results are considerably less, it appears as though 802.11n devices will be about five times faster than 802.11g devices, and will offer about twice the range.

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