802.11a

Release date Op. Frequency Throughput (typ.) Net bit rate (max.) Gross bit rate (max.) Range (indoor)
October 1999 5 GHz 27 Mbit/s[4] 54 Mbit/s 72 Mbit/s ~35 m[citation needed]

Main article: IEEE 802.11a-1999
The 802.11a standard uses the same data link layer protocol and frame format as the original standard, but an OFDM based air interface (physical layer). It operates in the 5 GHz band with a maximum net data rate of 54 Mbit/s, plus error correction code, which yields realistic net achievable throughput in the mid-20 Mbit/s[citation needed].

Since the 2.4 GHz band is heavily used to the point of being crowded, using the relatively un-used 5 GHz band gives 802.11a a significant advantage. However, this high carrier frequency also brings a disadvantage: The effective overall range of 802.11a is less than that of 802.11b/g; and in theory 802.11a signals cannot penetrate as far as those for 802.11b because they are absorbed more readily by walls and other solid objects in their path due to their smaller wavelength. In practice 802.11b typically has a higher distance range at low speeds (802.11b will reduce speed to 5 Mbit/s or even 1 Mbit/s at low signal strengths). However, at higher speeds, 802.11a typically has the same or higher range due to less interference