If 802.11g is so great, why bother with 802.11a? The answer comes down to one word: performance.
As Wi-Fi networks become larger and more complex, performance takes a serious hit. To address this problem, 802.11a uses OFDM to offer a data rate of 54 Mbps and operates in the reasonably uncluttered 5-GHz band.
802.11a offers many more channels in which to operate than 802.11b or 802.11g. With as many as 23, nonoverlapping channels, you can have up to 12 APs set to different channels in the same area without interfering with each other.
802.11a is popular in certain industries. Environments in which large data transfers are necessary might be wise to consider 802.11a because of the improved performance.
The pros of 802.11a are:
The cons of 802.11a are: