Much of the recent growth in wireless networks can be attributed to the adoption of the 802.11 standard, also known as "Wi-Fi". It is a standard for wireless communication that provides guidelines for the manufacture of networking hardware that ensures that networking communications protocols are compatible across different manufacturers. For example, a wireless network card manufactured by 3Com will work with a wireless access point manufactured by Lucent. Adoption of this standard has allowed for a drop in the price of wireless hardware, and in turn, helped it to grow.
802.11 Subcategories (802.11b / 802.11a / 802.11g / 802.11n)
- 802.11b - Toward the end of 1999, the 802.11b standard was ratified by the IEEE. The 802.11b standard operates in the 2.4 GHz unlicensed ISM spectrum. Because of abundant industry expertise in building 2.4 GHz radios for existing products like cordless phones, wireless LAN products based on 802.11b quickly arrived on the market, offering Ethernet-class data rates (up to 11 Mbps) and backward compatibility with the initial 802.11 standard. 802.11b products quickly penetrated the mass market because they were the first to deliver acceptable speeds at accessible prices. Furthermore, the Wi-Fi Alliance (formerly known as the Wireless Ethernet Compatibility Alliance) began to certify 802.11b products for interoperability with one another. Because 802.11b was the first technology to meet the requirements of enterprise LANs, much of the mainstream wireless infrastructure has been built on it. The 802.11a standard delivers data rates of 6-54 Mpbs using Orthogonal Frequency Division Multiplexing (OFDM) in the 5 GHz frequency bands. Because of difficulties in developing 5 GHz chips, 802.11a based products did not become available until late 2001.
- 802.11g - The 802.11g standard can deliver data rates of up to 54 Mbps in the 2.4
GHz frequency band. Since both 802.11g and 802.11b operate on the 2.4 GHz frequency band, they are
completely interoperable. Therefore, users can protect the investments they've made in 802.11b equipment
when purchasing compatible 802.11g products. Other characteristics of 802.11g are:
- High performance that satisfies bandwidth-intensive applications and areas with many wireless users
- Backward compatibility with the installed base of 802.11b wireless LANs, reducing upgrade costs
- Lower product costs compared to an 802.11a/b solution, because only one radio is necessary with 802.11g
- Good range compared to 802.11a, which lessens deployment costs due to fewer access points in most applications
- A method of prioritizing data packets to improve quality of streaming media, such as VoIP, voice and video conferencing
- Because of these features, 802.11g is quickly replacing 802.11b as the mainstream wireless LAN technology.
- 802.11a - The 802.11a standard delivers data rates of 54 Mpbs using Orthogonal Frequency Division Multiplexing (OFDM) in the 5 GHz frequency bands. Because of difficulties in developing 5 GHz chips, 802.11a-based products did not become available until late 2001. This has led to a low level of adoption and relatively high prices. A major problem is that 802.11a is not compatible with 802.11b.
- 802.11n - The latest wireless standard, published in October 2009. It allows for transfer rates of up to 100 MBps per channel. By aggregating several spatial streams, even higher data rates are possible. The standard allows for operations in both the 2.4 GHz and 5 GHz bands. 802.11n introduced a number of new technologies to improve the coverage area and reliability of the signal.
There are some other wireless network standards in use today such as "Bluetooth", which is intended for short-range communication between computers and peripherals, such as wireless phones, keyboards, mice, speakers, microphones, etc. The data rate of bluetooth is presently 24 Mbit/s, considerably slower than most WiFi links. The Bluetooth protocol is much more energy efficient than WiFi. For this reason, Bluetooth tends to be used with small, battery-powered devices as a cord replacement rather than for Local Area Networking between computers.