802.11g's claim to fame is 54Mbps raw data rate with 802.11b backward compatibility. The higher speed comes from using the Orthogonal Frequency Division Multiplexing (OFDM) modulation scheme that first was used in 802.11a. Backward compatibility comes from staying in the 2.4GHz band and supporting the Complementary Code Keying (CCK) modulation scheme used by 802.11b.
This second point is important, because every 802.11g product actually can automatically fall back to operating in 802.11b-only WLANs as well as mixed b/g and 11g-only.
This standard first took the consumer WLAN market by storm, even before the standard was released and "draft" 802.11g products started appearing, aimed squarely at consumers seeking higher wireless speeds. Once the standard was ratified, enterprise grade gear made the transition and today (early 2006) 11g is the wireless LAN market leader, primarily based on its good cost vs. performance.
Despite manufacturer's claims to the contrary, 802.11g products are generally not suited for streaming video. The problem is not speed, since enhancement techniques generally provide bandwidth to spare. The problem comes from 11g's use of the overcrowded 2.4GHz band. Most consumers just do not have a quiet enough RF environment to enjoy trouble-free wireless video. Audio streaming may be possible due to its very low (100's of kHz) bandwidth requirements, but again, success is highly dependent on environment.
There are two primary enhancement technologies for 802.11g products. Broadcom's 125* High Speed Mode (which started out as "Afterburner") works by removing as much overhead as possible from 11g transmissions. The main techniques used are data compression, and "frame bursting" (sending more data packets in the time allowed) with some other overhead-reduction techniques thrown in.
As mentioned earlier, products using this technology sometimes use the 125* High Speed Mode moniker directly, although Linksys prefers its own "SpeedBooster" branding.
The second enhancement technology is Atheros' Super-G (and Super-AG for its dual-band products), which is clearly described in this whitepaper (PDF link). Super-G starts with similar frame bursting, compression and overhead reduction techniques as Broadcom, but added a controversial "turbo" mode.
"Turbo" (now officially dubbed "Dynamic Turbo") combined two channels in order to boost real, application-level throughput as high as 50Mbps. But it did it at the expense of interfering with neighboring "legacy", i.e. 802.11b and g WLANs. Although Atheros was forced to modify the "turbo" mode behavior many times so that it didn't cause interference, it is thought that Super-G based products still wreak havoc in areas where wireless LANs are closely spaced.
Products using Super-G typically either use the term directly or somewhere quote its telltale "108Mbps" maximum data rate somewhere in the product literature.
Generally, you can achieve some throughput enhancement even when mixing products from different vendors, as long as you mix products using the same enhancement technology. But products will fall back to standard 11g speeds if you try to mix Super-G and 125* High Speed Mode gear.
A final note on enhancements is that both Broadcom and Atheros also have range enhancing technologies that you'll sometimes run across in products. Since specifying range is something that manufacturers would rather not do, they tend to play down these technologies. But for the record, Atheros calls theirs eXtended Range (XR) and Broadcom opted for BroadRange. Once again, you can download an Atheros XR whitepaper, but good luck trying to find something similar from Broadcom.
- Widest range of product types
- Relatively inexpensive
- Effective throughput and range enhancement technologies available
- Susceptible to interference from 2.4GHz cordless phones, microwave ovens and Bluetooth devices
- Susceptible to interference from neighboring wireless LANs due to only three available non-interfering channels available
- Heavy reliance on non-interoperable enhancement technologies
- Hard to tell what flavor of enhancement you have
Recommendation: If you're buying wireless today, you'll probably choose 802.11g.