The forthcoming IEEE 802.11n standard, promoted as the key to wirelessly sharing high-quality multimedia content throughout the home, still faces some hurdles on the way to making that vision a reality.
For example, vendors don’t know how they will handle the two radio frequency ranges that 802.11n will support — they’ll need some other standards to work alongside it — and the unlicensed spectrum used for wi-fi may simply not be able to support service providers’ commitment to deliver the high-quality content to subscribers, according to participants in a panel discussion at Intel’s recent Developer Forum, held in San Francisco.
The 802.11n standard, which is still under discussion by a working group of the Institute of Electrical and Electronics Engineers, can be used in both the 2.4GHz radio band, currently used for 802.11b/g, and the 5GHz band in use now for 802.11a. It is also intended to be backward-compatible with those existing specifications while delivering greater range and real throughput of 100Mbit/s — more than twice the speed of the current technologies. A compromise between two warring camps led to a draft standard in January, which will probably lead to final approval in about a year.
However, it’s not yet certain how 802.11n networks will use the two frequency bands, according to vendor executives on the panel. The standard could mandate that every product include radios for both bands or allow companies to sell 802.11n products that work in just one band, according to Miguel Pellon, vice president of technology standards at Motorola.
The 2.4GHz band would provide backward compatibility with 802.11b/g, the most common technology used by home wireless LANs today, but it also faces more interference from existing wireless LANs as well microwave ovens and Bluetooth short-wave wireless connections, says Yoshiharu Doi, a Sanyo Electric manager who represents Japanese consumer electronics vendors in the 802.11n standardisation process. For this reason, Japanese companies have decided it’s not ideal for entertainment applications such as high-definition video streams, Doi says. He envisions 802.11n products being able to shift between the two bands, moving to 5GHz for highly demanding uses.
Automating that process is critical to the technology’s success, says Phil Kearney, director of communications technology for Mac hardware at Apple Computer. Ordinary consumers don’t want to deal with it themselves, he says.
“My mother will hit me on the side of the head with a wooden spoon if I start mentioning ‘2.4’ and ‘5’ to her,” Kearney says.
The new standard can’t support high-quality video streams by itself, either, according to Mark Grodzinsky, product manager for wireless products at Intel.
That feat requires several other pieces, including the 802.11i standard for security and 802.11e for guaranteed quality of service, as well as the Wi-Fi Alliance’s quality-of-service specification, WMM (wi-fi Multimedia). However, all these will be available when 802.11n products hit the market, he says.
In any case, service providers that want to use wi-fi to deliver multimedia content around the homes of their subscribers will have a hard time making the service assurances they are used to making, according to Alan Cohen, senior director of product management for Cisco Systems’ wireless networking business unit. Because wi-fi operates on unlicensed frequencies it can’t deliver the same kind of guaranteed performance that carriers expect when they use wired technologies or licensed spectrum, Cohen says.
US cable operator Comcast is still examining ways to deliver television and other content, according to Comcast’s Mark Francisco, who asked the panel about using 802.11n for a “service-assured” offering.