EETimes reports "FCC backs HomeRF in 2.4-GHz wireless LAN battle"
Hi Jim,
Knowing you have an interest in the 802.11x standards battles, I've addressed this to you. Perhaps you, or any of our knowledgeable wireless contributors could chime in and either concur with the author, Patrick Mannion, that this is indeed a big deal, or maybe, possibly, its just another standards development that's not going to change the course of much of anything. I am in the utterly clueless camp as to how much weight to give this FCC decision. Any comments welcomed. <g>
eetimes.com
[[All emphasis is mine, intended to spare those who've got only a limited interest in the topic, and just want the facts, m'am. <g> ]]
FCC backs HomeRF in 2.4-GHz wireless LAN battle
By Patrick Mannion EE Times (09/01/00, 3:37 p.m. EST)
MANHASSET, N.Y. — In a landmark ruling, the Federal Communications Commission came down on the side of the HomeRF Working Group on Thursday (Aug. 31) by agreeing to allow frequency-hopping, spread-spectrum radios in the 2.4-GHz band to increase their bandwidth from 1 MHz to 5 MHz. The ruling — a coup for the HomeRF camp — opens the door to more-heated competition between HomeRF and 802.11b in wireless LANs and raises interference issues for a much more crowded 2.4-GHz spectrum.
The rule change will essentially allow networks based on this technology to increase their signaling rate by a factor of five — from 2 Mbits/second to 10 Mbits/s. The higher data rates are significant in light of a drumbeat of demand for low-cost, high-speed home networks that will support upcoming broadband services such as streaming audio and video and cordless telephony.
The ruling, which goes into effect immediately, grants almost all the HomeRF's requests. It allows frequency-hopping signals in the 2.4-GHz band to operate at 1, 3 or 5 MHz, with at least 15 non-overlapping channels spread out over a total span of 75 MHz. The average time of occupancy on any frequency shall not be greater than 0.4 seconds, within a 30-second period. The maximum output power is 125 mW at 5 MHz, vs. the 200 mW the HomeRF group had requested.
Five key, seemingly innocuous lines appearing in Appendix B of the ruling [[Ed. note, see below for URL and citation from the FCC's ruling.]] end months of gut-wrenching anticipation on the part of those involved in wireless networking. Ever since the HomeRF Working Group filed the letter late last year asking for the change, the FCC's Office of Engineering and Technology has been flooded by petitions opposing it.
Led by proponents of the 802.11b standard (for direct-sequence, spread-spectrum nets at 11-Mbit/s) and by many involved in Bluetooth short-range RF networking, the petitioners argued that the change proposed would lead to excessive interference with other Part 15 devices in the 2.4-GHz band. They also argued that multipath and interference problems would prevent devices operating under the proposed new rules from achieving the claimed higher data rates. The detailed debates the FCC waded through to reach its decision are outlined in the ruling, available at the FCC's Web site.
Changed landscape
All the while, 802.11b penetration in the enterprise — and to a certain extent, in the home — has been proceeding, thanks to a lack of any serious threat from its bandwidth-handicapped frequency-hopping competitor. Now the landscape has changed drastically, and the FCC is well aware of the implications.
"The Commission's action represents a reasonable engineering compromise between the risks of increased interference and the desire to accommodate new technologies," said FCC Chairman William Kennard. Hewing to his policy of positioning the FCC as a consumer advocate, Kennard said the ruling "will facilitate the development of new, high-speed data devices for business and consumer applications such as transmission of CD-quality audio and video streams from home PCs to portable devices."
However, other FCC officials expressed concern about the effect of rule changes on spread-spectrum devices already in use by consumers. "We recognize that the FCC engineering staff has worked hard for more than a year to assess the interference claims of [opponents] and adjust the proposed amendments in an attempt to balance the benefits of the new spread-spectrum devices against the potential for interference to existing devices," Commissioners Susan Ness and Harold Furchtgott-Roth said in a joint statement.
Meanwhile, the ruling was cause for jubilation at the HomeRF Working Group. "[The ruling] allows full use of the potential of HomeRF, along with full compatibility with previous technology and a ready upgrade path," said Ben Manny, chairman of HomeRF and director of residential communication for Intel Corp.
"We're delighted that the FCC, despite a lot of noise and heat that was only intended to cause confusion, came out with a very balanced and fair compromise," said David King, chairman and chief executive officer of Proxim Inc., a supplier of HomeRF products. "The decision allowed what was a competitively unbalanced market to become balanced again."
Proxim plans to release samples of wideband frequency-hopping silicon by year's end and to have production volumes by early in 2001.
For the 802.11b camp, the ruling, though not unexpected, was a bitter pill. "So far [HomeRF] has been presented as ideal for the home but you have to ask, if it's so good, then why is it being portrayed as a home-only solution?" said Jim Zyren, director of enterprise and OEM products at Intersil Corp., the leading provide of chip sets for 802.11b wireless LANs. "The short answer is that it's not an enterprise play because it doesn't have the reliability, the interference immunity or the range. The consumer is one thing, but the enterprise is more educated and bets bigger dollars."
He also said the scheme "will be extremely susceptible to interference" from direct-sequence spread-spectrum and other radios. "The current HomeRF products are susceptible to begin with, but if you open up the channel width by a factor of five, because of the type of waveform they use it'll be even worse," Zyren said.
Intel's Manny disagreed. "We're targeting the home," he said. "There aren't a lot of other sources of interference, and we've done work to reduce the effect of microwave ovens [which operate at 2.4 GHz]."
Kevin Negus, vice president of business development at Proxim and technical co-chair of HomeRF, said frequency-hopping systems are far less susceptible to interference than direct-sequence schemes due to the nature of the random patterns of the two. "Perhaps more important are the MAC-layer retry mechanisms and the hop-set adaptation algorithms that are built into HomeRF," he said.
In the wake of the decision, companies on both sides of the issue were pondering the impact on product development. Al Petrick, director of marketing and business development at ParkerVision Inc. and vice chairman of the IEEE 802.11 working group, said that while he doesn't expect to see product until next year, the race is on in the 2.4-GHz band to see who gets the lion's share.
"Right now I'm more afraid of Bluetooth interference on 11b, as there will be more of these devices out there," Petrick said.
Benefit to Bluetooth
Ironically, Bluetooth itself stands to benefit from the ruling. Because the FCC didn't place a figure on the maximum number of hops allowed, Bluetooth, which is also a frequency-hopping technology, can use the ruling as an opportunity to increase its potential data rates to 10 Mbits/s over short distances.
Still, "right now our focus is on getting the 1-Mbit standard up and running," said David Lyons, chairman and chief executive officer of Bluetooth-chip provider Silicon Wave and an associate member of the Bluetooth special-interest group. He said he foresees camera makers looking to incorporate a high-rate version of Bluetooth for downloading graphics to PCs in close proximity.
Silicon Wave is among the Bluetooth backers that had initially opposed such a ruling. "Our original objection was based on the grounds that the 5-MHz bandwidth at 200 mW would marginally increase interference," Lyons said. "But with the power reduced to 125 mW, that's no longer an issue."
Why did HomeRF get the FCC's nod? "The key here is voice," said Proxim's Negus. "HomeRF borrows heavily from the Digital European Cordless Telephone technology, via a partnership with Siemens, and reuses all the call-stack capability in DECT, whereas .11b has no mapping into any known digital phone standard."
HomeRF could potentially provide low-cost, toll-quality voice support for up to eight channels. To date, 802.11b has relied on a voice-over-Internet Protocol methodology, with its inherent delays and relatively poor call quality. The IEEE working group aims to finalize a quality-of-service implementation, but this could take a year or two.
"By building on DECT, we're leveraging off a 200 million-handset market over the next two years," Negus said. "The price points for this silicon, which is in its fifth and sixth generation, are very low."
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URL for the FCC order amending Part 15:
fcc.gov
This is the language in Appendix B:
"(iii) Frequency hopping systems in the 2400 - 2483.5 MHz band may utilize hopping channels whose 20 dB bandwidth is greater than 1 MHz provided the systems use at least 15 non-overlapping channels. The total span of hopping channels shall be at least 75 MHz. The average time of occupancy on any frequency shall not be greater than 0.4 seconds within a 30 second period.
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Comments welcomed. Oh BTW, and FWIW Mr. Market thinks this a good thing for Proxim, YMMV. <g>
Best, Ray |
