802.11a
At the same time 802.11b was approved, another high-speed option, 802.11a, also appeared. 802.11a operates in the 5-GHz spectrum. It is not compatible with 802.11b, but it does not interfere with it. (A and B networks can coexist in the same physical space.) Think of it like this: You can hold a cell phone in one hand and a walkie-talkie in the other hand. They can both work at the same time, just not with each other. 802.11a (see Table 2.3) has 12 non-overlapping channels that operate at 54 Mbps, but the coverage area is much smaller then 802.11b.
| Frequency: | 5 GHz |
| Channels: | 12 USA |
| Speed: | 54 Mbps |
| Range: | Appx. 60 feet (varies) |
| Encoding Scheme: | OFDM |
| Modulation Technique: | BPSK (6 & 9 Mbps)
QPSK (12 & 18 Mbps) ... |
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