This is a Wi-Fi wireless network communication standard. As one of the 802.11 series it is one of the Institute of Electrical and Electronics Engineers (IEEE) standards. 802.11a wireless networks usually support a maximum bandwidth (theoretical) of 54 MBps.
This establishes a quite large advantage over 802.11b Wi-Fi that only supports about 11 Mbps. This also means that its performance is on par with that of an 802.11g Wi-Fi network.
There are some downsides however, an example of one is that past installations of an 802.11a Wi-Fi network have been limited as a result of corporate environments due to the relatively higher costs associated with the hardware equipment.
An 802.11a Wi-Fi network transmits radio signals in the frequency range of above 5 GHz. That range in the wireless spectrum is generally regulated in many countries.
The regulations were established to prevent signal interference with other equipment transmitting signals on the wireless spectrum as well such as cordless phones.
802.11a networks are also limited in that they are obstructed much more by objects such as a brick wall than alternatives such as the 802.11b/g series.