802.11a is an IEEE standard used for transmission of data over a wireless network. This standard sets the media access control (MAC) and physical layer (PHY) specifications that are required for the deployment of wireless LAN (WLAN) technology.
Standards are essential in technology as they simplify product development and reduce costs that do not add any value. Also, standards form the building blocks of communication technology.
History of 802.11 standards
Wireless standards are created and maintained by IEEE (Institute of Electrical and Electronics Engineers) LAN/MAN Standards Committee also known as IEEE 802.
The base version of these standards (802.11) came in 1997 with amendments released subsequently. Both 802.11a and 802.11b released in September 1999.
Wireless systems use radio frequency (RF) signals for communication. Radio waves are electromagnetic waves that fall in the range of 20 kHz and 200 GHz.
In the 1980s, U.S. government opened three wireless frequencies for public use – 0.9 GHz, 2.4 GHz and 5.8 GHz. 5.8 GHz is also sometimes called 5 GHz.
Out of this 2.4 GHz and 5.8 GHz were used in different Wi-Fi standards. 900 MHz (or 0.9 GHz) was not found to be useful for data networking and thus was limited to cordless phones.
Some essential elements of this wifi standard are as follows.
- Networks that use 802.11a operate at radio frequencies between 5.725 and 5.850 GHz, which significantly improves the performance of 802.11a over 802.11b. Also, the frequency spectrum employed by 802.11b (2.4 GHz to 2.5 GHz) is shared with different household appliances and medical devices.
- 802.11a uses a modulation scheme known as orthogonal frequency-division multiplexing (OFDM). OFDM is a method to manipulate digital signal wherein a single data stream is split into separate narrowband channels. All these channels operate at different frequencies which helps in reducing interference and crosstalk.
- 802.11a can transmit data at a rate of 54 Mbps. This was a vast improvement over the base standard 802.11 and 802.11b.
Despite supporting a lower bandwidth, 802.11b was more popular because most routers and wireless cards at the time were manufactured using the 802.11b standard which could not be used for 802.11a because of differences in frequency bands.
Issues with 802.11a wireless networks
802.11a uses 5GHz frequencies along with OFDM modulation for transmission as it helps improve network performance by reducing interference.
However, these frequencies significantly limit the range of the network. 802.11a is also greatly influenced by brick walls and other obstructions.
Other IEEE wireless standards
Some other popular IEEE standards that followed 802.11a and 802.11b include 802.11g in 2003, 802.11n in 2009 and 802.11ac in 2013.
802.11g improves 802.11b regarding the range of the network while maintaining the speed whereas 802.11n and 802.11ac both improve on speed and coverage.
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