802.11a and Dual-Band
This standard debuted in late 2001. Its main attractions are that it operates in the less crowded 5GHz frequency band, and has a maximum data rate of 54Mbps. It was the first 802.11 standard to use OFDM, which is key to achieving the 54Mbps data rate. It has thirteen non-interfering channels - 8 lowband and 5 highband (though not every card supports the highband channels) vs. three for 802.11b, making it easier to set up large, multi-AP installations.
First-generation 11a products suffered from shorter range than 802.11g products and developed an "inferior range" reputation that still seems to dog the technology today. But the problem was eliminated in second-generation products (see our Second-generation 802.11a NTK for more info), such that there is little difference in range between standard, i.e. unenhanced 11a and 11b/g products.
Consumers will need to hunt for 802.11a-only products, but there is little reason to do so. Dual-band products that cover all three standards (11a/b/g) are more widely available and much more flexible. They're actually less expensive than 11a-only products, which are now manufactured mainly for enterprise use and special applications. But dual-band products are still harder to find, since manufacturers seem to have a love / hate relationship with them.
Dual-band briefly seemed poised for a comeback in late 2004 when manufacturers started to make a simiplistic pitch of "11b/g for data, 11a for multimedia". But once faster "pre-N" products started to appear, they all seemed to shift back to pitching those (2.4GHz) products for multimedia streaming.
Atheros has virtually owned the 802.11a chipset market, so you'll find the same throughput and range enhancements as Super G, but called "Super AG". The good news is that, unlike 802.11b/g, 802.11a doesn't have overlapping channels. So although Super AG's "Turbo" mode takes up two channels, there are plenty more for neighboring users to change to to avoide interference.
- More non-interfering channels than 802.11b/g
- Less likely to run into interfering neighboring WLANs
- Neighboring WLANs can tune away from "Turbo" users
- Products are more expensive
- Not as wide a range of products available
Recommendation: 11a products can help avoid interference from 2.4GHz cordless phones, microwave ovens, and neighboring wireless LANs. Definitely worth considering if any of these problems are bothering you, or if you want to try streaming wireless video. Don't be tempted by cheap 11a-only products on eBay, though, since you'll most likely be getting products using first-generation chipsets, which have inferior range.