Wi-Fi FACTIONS STIR CONFUSION

In the Wi-Fi alphabet, “a” comes after “b,” but just before “g,” and that's proving to be a thorny issue for companies trying to cash in on a growing technology phenomenon. The 802.11a data standard, which operates at 54 Mb/s in the 5 GHz spectrum frequency band, was originally designed to succeed the market-dominant 802.11b standard, which transmits at speeds of 11 Mb/s at 2.4 GHz. However, several companies — including Apple and Microsoft — do not support 802.11a. Some are waiting for the 802.11g 54 Mb/s standard at 2.4 GHz, which is set for approval this summer.

The waning support for 802.11b is damaging the market prospects of 802.11a. Meanwhile, that negative image was enhanced recently when an Apple Computer executive slammed 802.11a in published reports as a standard that didn't “make sense.” The criticism came just days before the Wi-Fi Alliance's first-round certifications of 802.11a products, stealing the thunder of what was to be a major step forward for the standard and for interoperability between 802.11a products.

Wi-Fi STANDARDS STACK UP

802.11b: The dominant market standard. Finalized in late 1999. 11 Mb/s data rate at 2.4 GHz. Uses the complementary code keying (CCK) modulation scheme. Expected to reap industry-wide Wi-Fi node revenues of $1.17 billion this year, according to Allied Business Intelligence.

802.11a: Standard has been available since last year, but not widely supported or accepted. 54 Mb/s data rate at 5 GHz. Uses the orthogonal frequency division multiplexing (OFDM) modulation scheme, which allows faster data transmission than CCK. ABI says it will bring in industrywide node revenues of $128 million this year.

802.11g: Standard will be ratified this summer and just recently hit the market. Uses OFDM to allow 54 Mb/s at 2.4 GHz. Will be supported by virtually every company that now supports the other two standards. ABI says the market will be worth $178 million this year.

Regardless, 802.11a vendors are moving in to stem the growing furor, saying there is a need for clearer, more abundant spectrum associated with the frequency of 802.11a and that the industry should focus on supporting all flavors of the broadening 802.11 standards family by working with emerging dual-band solutions. “It's a debate that doesn't need to exist,” said Mike McAndrews, director of business operations at Cisco Systems' wireless networking business unit. “Standards at both frequencies should be used.”

Rich Redelfs, president and CEO of Wi-Fi chipset developer Atheros Communications, said the debate is stirred because some companies are unable to make 802.11a work. However, he declined to connect his comments to Apple or any other company.

Another source, who requested anonymity, said, “Apple doesn't support 802.11a, so what do you expect? This is their way of making up for it.”

The 802.11a standard was created for 5 GHz because Wi-Fi developers learned in the early days of 802.11b deployment that the orthogonal frequency division multiplexing (OFDM) modulation scheme used with the 802.11 protocol at 5 GHz allowed for much greater bandwidth. The 802.11b standard was founded on the complementary code keying (CCK) modulation scheme. However, long after 802.11a was in development with OFDM, technologists discovered that they also could use OFDM technology at 2.4 GHz, which required no frequency change from well-established 802.11b.

The advancements in OFDM technology set up 802.11a as 802.11b's immediate successor, but it also established a competing standard — 802.11g — that would follow shortly on its heels. So which standard should companies follow in their investments, product developments and purchases?

“The right answer is all of the above,” Atheros' Redelfs said. “Saying 802.11a is dead is like saying 100 Mb/s Ethernet is dead. It's the new standard that gave us faster speeds.” He said device makers should build dual-band solutions that implement both 802.11b and 802.11a.

McAndrews added, “All three can be used. 802.11g will be easier for companies that already have 802.11b products in place.”

However, the transition from 802.11b to 802.11g may not be so simple. For 802.11g to work seamlessly with 802.11b, products must switch to a compatibility mode when they cross into an area where the protocols overlap, said Brian Grimm, communications director for the Wi-Fi Alliance. That switch causes a slight throughput delay that affects the available bandwidth.

802.11a offers a few obvious advantages over the other two standards, Grimm said. Because consumer products such as microwave ovens and cordless phones operate near the 2.4 GHz frequency, interference is possible. Also, while there is a limited 83.5 MHz of spectrum allotted to Wi-Fi in that frequency band, there is about 255 MHz of unlicensed spectrum at 5 GHz. If proposed congressional legislation seeking more spectrum for Wi-Fi at 5 GHz is passed, the real estate at 5 GHz could become even more attractive.

The 802.11a certifications from the Wi-Fi Alliance, which involved seven products from five different vendors, will instill confidence in conservative enterprises and carriers that were waiting for interoperability assurances before they purchased equipment, Redelfs said.

Still, even with the benefits of 802.11a, the market for that standard has been slow to develop. And despite the Wi-Fi Alliance certifications, it may remain so. Research company Forward Concepts said that 802.11a will have a “short life” as a singular solution and that its future deployment relies entirely on the emergence of dual-band solutions. Also, Allied Business Intelligence said revenues for both 802.11g and dual-band 802.11 a/b will outstrip pure 802.11a revenues as early as this year.

In fact, while the recent Wi-Fi Alliance certifications followed a rapid two months of testing between vendors, more than a year passed before tests were initiated on the first 802.11a products that appeared.

“802.11a has been in the market for a year or more, but you need at least two chipsets and at least four products to really test interoperability,” Cisco's McAndrews said. Atheros was the first company to reach the market with an 802.11a chipset, and Cisco followed in November when it acquired 802.11a developer Radiata. No other firms are currently producing 802.11a reference designs.

Grimm, however, said that 802.11a has taken off in countries such as Japan where 802.11b had little impact. Such opportunities will ensure the need for 802.11a, he said, adding that the current debate is just another turn in the evolution of a technology.

“802.11a was going to replace 802.11b, and now it's people talking about 802.11g replacing 802.11a,” Grimm said. “Soon we'll have dual-band, and next there will be multimode.”

Indeed, though products compatible with both Wi-Fi data standards and mobile data schemes such as CDMA 1XRTT and GPRS are still far off, most agree that the industry is heading in that direction.

“It would be great to have a phone that did both,” McAndrews said. Instead, Wi-Fi users can look forward to an increasing number of dual-band devices based on chips from companies like Atheros that will help the industry forget about the standards debate. Intel said it also will produce a dual-band chip by the end of the second quarter.

The entire situation is reminiscent of a period during which cellular networks and PCS networks were at odds until dual-band mobile phones became widely available. “With dual-band devices, customers won't know or care,” McAndrews said.