From
Infoworld
By
Ephraim Schwartz
Scott Tyler Shafer
With the Federal Communications Commission proposing to nearly double 802.11a’s available bandwidth, Wi-Fi is on course to become as available as the air it travels through.
Posted last week, the FCC proposal would add 80 percent (255MHz) to the 300MHz of spectrum currently available in the 5GHz band. The additional spectrum would reside in the middle band, from 5.470GHz to 5.725GHz.
The change would offer many major benefits, according to the FCC.
The additional bandwidth means you can have higher density of use in a given geographical area because there is much more spectrum available. It can also be channelized in many ways,” said Edmond Thomas, chief of the office of engineering and technology at the FCC in Washington.
The bandwidth proposal would increase the number of channels 802.11a can operate on to 24. At present, IEEE 802.11b has three channels available; 802.11a has 11.
The added spectrum would also match the 5GHz middle band currently allocated in Europe.
“The Europeans decided to use the middle band to get out of the way of radar,” said Craig Barratt, CEO of Atheros, a Sunnyvale, Calif.-based manufacturer of IEEE 802.11x chip sets.
Under the FCC guidelines, additional spectra must use DFP (Dynamic Frequency Protection) so that when a WLAN detects radar using the same band it can switch to another channel.
The FCC chose the same band as Europe's in order to have overlapping bands throughout the world, according to Ken Dulaney, chief wireless analyst at Gartner in San Jose, Calif.
“This simplifies things a lot. If you buy a radio in a country that doesn’t have support for that band, you can’t use it,” Dulaney said.
Given the proposed increase in spectrum, companies would have more flexibility in allocating specific channels for particular applications.
“If you have enough channels set aside for dedicated use, your QoS [quality of service] problems are gone,” said Leigh Chinitz, CTO of Proxim in Sunnyvale, Calif.
Specifying channels will also make the use of VoIP (Voice over IP) far more practical, Chinitz said, adding that VoIP requires the WLAN to offer continuous coverage and high capacity.
“Voice over IP will be carried over wireless LANs by allocating a couple of channels just for VoIP,” Chinitz said.
The proposed specturm addition is also receiving a warm reception from Cisco Systems. Christine Falsetti, Cisco’s director of wireless and mobility marketing, said the FCC’s decision to make the 5.4GHz band usable in an unlicensed way is a positive step.
“Allowing access to this spectrum allows more channels and more innovation,” Falsetti said.
But Gartner’s Dulaney believes the FCC proposal does not go far enough. Dulaney conceded that, in the short term, the increased number of channels would ease conflicts between competing networks but added that the open bands, IEEE 802.11x, are too open.
“We need an unregulated technology in a regulated band,” Dulaney said.
There are a number of other issues surrounding the FCC proposal that could delay deployment of devices that would be capable of accessing the additional spectrum.
Most of the hardware available today is not tuned to cover the proposed spectrum. In fact, many 802.11a devices cover only the lower and upper bands, according to Proxim’s Chinitz.
“It may be possible that current hardware can’t handle the middle band. It will probably require new hardware,” Chinitz said.
If the United States formalizes the DFP rules, then the Atheros chip, which already complies with the European standard, will be compliant and will address the entire 5GHz band. But if the United States adopts significantly different rules, which Atheros’ Barratt said is unlikely but possible, the deployment of access points that cover a larger range of channels will be some time in the coming.
According to Barratt, such a situation would be akin to having a television that works only on a few channels. The CEO did not speculate, however, on when new products would be available if the need to comply with a different set of rules arised.
“For the present, IT departments should make sure that they buy access points that address the entire 5GHz spectrum,” Barratt said.
At the least, Wi-Fi vendors would need to flash the access points with upgraded software for it to access the increased capabilities.
With the unprecedented support of the FCC and the improvements in the technology already in the pipeline, the future is bright for Wi-Fi.
Based on 24 channels at 54Mbps, users could share a wireless Ethernet throughput of 1Gbps, enough to replace many wired networks. Using the same 24 channels at a more conservative 24Mbps, users could share 600Mbps.
According to Dulaney, the IEEE 802.11n committee is also examining the possibility of doubling up the bandwidth by bonding channels.
The only dissenting note comes from an executive in the cellular industry who sounded something like the fairy in Sleeping Beauty who wasn’t invited to Beauty’s christening.
“Wi-Fi has truly become the golden child, and the wireless carriers are left feeling like the red-headed stepchild. We spend so much time to get more spectrum, and we are paying through the nose for it. But it is important not to get too caught up in one technology like Wi-Fi. Look what happened to eight-track tapes,” said the cellular executive, who asked not to be identified.
Ephraim Schwartz is an editor at large at InfoWorld. Scott Tyler Shafer is an InfoWorld senior writer.
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