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802.11g's "Extreme" Emergence

by Adam Engst and Glenn Fleishman
01/23/2003

In 2002, Wi-Fi--mostly in the form of 802.11b equipment--ruled the land. The faster, 54 megabit-per-second (Mbps) 802.11a devices that shipped during 2002 seemed interesting, but because they used a different frequency than 802.11b and also cost more, only a small number of early adopters and testers bought in.

More promisingly, 802.11g winked at us from the horizon. That standard runs, like 802.11a, at 54 Mbps but with full backward compatibility with 802.11b. Because of political and technical conflicts, the specification's IEEE committee work dragged on, but a final version appears likely to be ratified by summer or fall 2003.

Technology doesn't wait for engineering groups, though: against some the better judgment of some industry experts, several companies have started to ship equipment based on chipsets that use a draft version of 802.11g to achieve the higher speed and better indoor signal characteristics.

Apple, of course, was one of the first out of the gate--just like with 802.11b--announcing new products under the AirPort Extreme name in January 2003 at the Macworld Expo. But Linksys, Buffalo, and Belkin--in roughly that order-- beat Apple to the punch by shipping a variety of gateways and adapters in December 2002 and January 2003. Apple has released substantially more detail about their equipment, while also offering a few interesting features in their new wireless gateway that may tempt people with no Macintoshes in sight.

Moving Forward and Backwards

The 802.11g specification uses a relatively new method of encoding bits onto radio waves in such a way as to squeeze up to 54 Mbps of raw data across a single channel. (For the technical among you, this method is called Orthogonal Frequency Division Multiplexing (OFDM) and is similar to the way DSL puts bits onto copper wire.)

As is the case with most theoretical network throughputs, the net throughput of real data--the actual contents of files or transactions--provides somewhere between 20 and 30 Mbps. In contrast, 802.11b's 11 Mbps raw throughput generally translated to 4 to 6 Mbps at best, and it wasn't uncommon to drop below that as distance from the base station increased.

802.11g is attractive because it includes full backwards compatibility with 802.11b. This compatibility isn't optional for manufacturers; it's a mandatory part of the spec. 802.11g also has several intermediate steps for speed, so you don't just drop from 54 Mbps all the way down to 11 Mbps.

One of 802.11g's big advantages over 802.11b is that it handles the inevitable signal reflection better. Radio signals bounce off different things--floors, metal, even the air around you--at different angles and speeds. A receiver must reconcile all the different reflections of the same signal that arrive at slightly different times into a single set of data. 802.11g (like 802.11a) slices up the spectrum in a way that enables receivers to handle these reflections in a simpler but more effective way than 802.11b.

As of early 2003, 802.11g has not been finalized and ratified by the IEEE, the engineering group that develops new standards. Ratification should happen relatively soon, in summer or fall 2003. Until then, the 802.11g "standard," as Steve Jobs called it so confidently, remains in draft form, although that hasn't stopped several chip manufacturers from shipping the silicon necessary to implement the current draft of 802.11g. (Apple's Web site now calls 802.11g a draft, reflecting reality.)

Also note that the Wi-Fi Alliance hasn't included 802.11g as part of its certification suite. The Wi-Fi Alliance tests equipment to make sure it works according to spec and is interoperable with all other certified equipment; if so, the maker is allowed to use the Wi-Fi logo. Until 802.11g is finished, the Wi-Fi Alliance has no way of guaranteeing that different 802.11g devices will work with one another, meaning that it will likely be some time after ratification that the Wi-Fi Alliance considers adding 802.11g to the Wi-Fi certification suite. Some of our sources speculate that a testing program could be in place as early as summer, but final certification almost certainly wouldn't start until at least late 2003.

That's not to imply that compatibility is likely to be a major problem. Manufacturers have significant motivation to maintain compatibility with other makers. No one wants to sell equipment that won't play nice with others because to do so would undermine confidence in the entire technology. In the worst case, unless a piece of hardware is designed extremely poorly, two incompatible 802.11g devices should be able to talk at 802.11b speeds.

Compatibility problems are particularly unlikely among different devices from the same manufacturer. Apple AirPort Extreme Base Stations will happily communicate with AirPort and AirPort Extreme cards, for instance. However, good compatibility likely goes farther. Apple's equipment relies on chips from Broadcom, as does 802.11g gear from Linksys. For that reason, and because Apple and Linksys represent the largest early 802.11g consumer market share, it's likely that Apple and Linksys equipment will be compatible. Later equipment makers will have to meet Broadcom's specs rather than vice versa. Sometimes standards are set merely by shipping the most devices.

One way or another, compatibility will not be an issue in the long run, whether you buy hardware now or later. Apple has promised firmware upgrades as the standard stabilizes, and Apple has done a good job thus far providing these kinds of updates to the older AirPort equipment.

On a related front, Apple hasn't committed to or rejected support for WPA (Wi-Fi Protected Access), the security update that fixes encryption problems and removes complexity from securing local wireless network connections. They said that they will monitor whether WPA becomes widely adopted and evaluate their response based on usage. Again, if Apple were to support WPA, that support would appear in the form of a free firmware update. Meanwhile, many other vendors are already promising WPA support. For instance, D-Link says their new 802.11g devices will support WPA with a firmware upgrade by the second quarter of the year.

AirPort Extreme Base Station

Apple offers two different AirPort Extreme Base Station models, priced at $200 and $250. Both units have 10/100 Mbps WAN and LAN ports, sport a USB port for printer sharing (but not spooling), and can bridge to other AirPort Extreme Base Stations, acting as an access point and a bridge simultaneously. The $250 unit also includes a 56K modem and a jack for an external antenna.

(Early reports from Apple don't make clear whether the company will only offer a Macintosh configuration utility or provide an unsupported or supported Windows console as well, as they do with the older "snow" Base Station.)

The 10/100 Mbps bump up in speed on the WAN port recognizes that some users might be hooking into wide-area networks or broadband connections that provide more than 10 Mbps of bandwidth (that's unfortunately not true for us, so we can't test that feature). If you're only running a 10 Mbps wired Ethernet, it might also be time to upgrade to 10/100 Mbps switches if you're also installing AirPort Extreme equipment to take full advantage of the intra-network speed.

The addition of USB printer sharing enables a network of Macs to share a printer without connecting the printer to a Mac that must be turned on whenever anyone on the network wants to print. However, the printer itself must be turned on: Apple confirmed that this feature is indeed "printer sharing", which makes it seem like the printer is connected to each machine, rather than "printer spooling", in which print jobs are sent to the print spooler, stored in a file, and then printed out whenever the printer becomes available. (Adam absolutely adores print spooling because his printer is seldom on, and whenever he turns it on, his print spooler immediately prints all the waiting print jobs.)

In the past, adding an external antenna to an AirPort Base Station required serious surgery that made a mockery of your warranty and required significant manual dexterity. Now, with the $250 model of the AirPort Extreme Base Station, you can simply plug an external antenna into the Apple-proprietary antenna jack.

Don't blame Apple for yet another proprietary jack--the FCC mandates that any wireless networking equipment that can take an antenna must feature a hard-to-find connector. That's because the FCC doesn't want just anyone attaching uncertified antennas that could spew more than the legal amount of signal. (An uncertified antenna is anything that the manufacturer didn't have the FCC test with a given gateway or card.)

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