Engineers who want to draft a standard for gigabit-class Wi-Fi are placing their bets on the same 60-GHz spectrum in use by another wireless standard in the works. The two groups will discuss the issue in a teleconference later this month in an effort to avoid a conflict during a major standards gathering in July.
The teleconference likely will be one of the first volleys in a protracted battle to define the future of high-bandwidth, short-range wireless networking for emerging markets such as home networks. That's because many companies eager to deliver multigigabit wireless local and personal area networks are converging on the 60-GHz band.
"From a regulatory point of view, 60 GHz is really the only cost-effective approach" for such high data rates, said an engineer involved in one of the efforts who asked not to be identified.
The IEEE 802.11 study group on very high throughput (VHT) will talk with the IEEE 802.15.3c group on wireless personal area networks (WPANs) via teleconference on June 19. According to the rules of the IEEE, the newer VHT group is at a stage where it must show it has technologies and market applications that are sufficiently different from the work of the .3c effort if it hopes to gain approval from senior IEEE staff to draft its standard.
The VHT group is trying to pave the road map for Wi-Fi,used in millions of notebook computers and home networks and a growing number of cell phone and MP3 players.
The .3c effort is aimed at delivering a capability for WPANs that,
for example, could send uncompressed high-definition video between a set-top box and a wall-mounted LCD TV.
"The two groups are trying to talk constructively in June to avoid fighting in July," said the source, referring to the IEEE 802 plenary session to be held in Denver July 13-18. "The leaders of both groups are doing a good job trying to get everyone to work together."
In order to be technically different, the VHT group could define a standard that includes support for fast switching among Wi-Fi at 2.4, 5 and 60 GHz. It also could define a capability for devices to negotiate a move at the lower frequencies to high-bandwidth 60-GHz links, he added.
Defining divergent application segments--another differentiation the IEEE requires--could be tougher. Asked what apps the VHT group might define, the source said, "That's an answer I don't have yet."
The .3c group focused its standard on two applications. One is distribution of uncompressed high-definition video. The other is high-bandwidth synchronization of devices, such as wirelessly downloading a video from a kiosk to a portable media player.
The VHT group is expected to spawn two separate standards efforts. One will look to enhance the spectrum efficiency of Wi-Fi below 6 GHz to allow aggregate throughout of up to 1 Gbit/second. That could enable more users to get on a single access point or have more throughput from a site.
The other effort will seek to define a single link at 60 GHz that could deliver up to 1 Gbit/s. Both efforts have defined their criteria and are ready to move forward, said Bruce Kraemer, chair of the overarching 802.11 group.
As many as 140 engineers have been attending the VHT meetings, representing a broad swath of the Wi-Fi community, Kraemer added.
'Competition is good'
The VHT and .3c groups probably will find a way forward to define separate specs, and products based on them probably will compete in the market, said Craig Mathias, consultant with the Farpoint Group (Ashland, Mass.).
The two will compete with other high-bandwidth home networking options, such as various flavors of ultrawideband, as well as proprietary techniques by companies such as Amimon. Several of the options were displayed in prototype products at the Consumer Electronics Show in January.
"There are a lot of techniques out there, and ultimately it may come down to one or two, but in the early days you don't want to discourage any approach," said Mathias. "You have really smart people working on really hard problems, and no one will get it all right."
Mathias noted that Bluetooth and Wi-Fi coexist--serving different applications--at 2.4 GHz. And the IEEE has tolerated competition for technologies it helped develop, such as the 802.16e WiMax and .20 standards, Token Ring and Ethernet."Ultimately, there will be conflict in the market, and that will be a good thing," he said.
Startup SiBeam has a chip coming to market based on the ad hoc Wireless HD specification. SiBeam is participating in the .3c work, and some of the options in the current draft of .3c are very similar to the Wireless HD spec.
Wi-Fi giants such as Atheros and Broadcom likely will wait on the VHT process before developing 60-GHz Wi-Fi chips. It is too early to speculate which companies might have an edge in the brewing technology battle, Mathias said.
"As the Ozmo announcement indicates, WLANs and WPANs are on something of a collision course," said Mathias, referring to the startup that has released 802.11 chips competing with Bluetooth for design wins in headsets, keyboards and mice.
The VHT group wants to get approval in July on the definition and rationale for the standards it envisions so it can officially begin work on them.
The .3c group is already well along in the standards definition process and hopes to have an initial letter draft available by early 2009. The .3c work could be adopted as a standard by the ISO as early as May 2009.
The .3c work basically is split into two modes for its two application scenarios. One mode uses a single carrier to make it easier to support 1- to 2-Gbit transmissions in a battery-operated terminal. The other mode uses orthogonal frequency-division multiplexing for higher-speed data transmissions. Terminals can support one or both modes.
Direct interference between .3c and VHT approaches or multiple systems using either approach should not be a problem, the source said. That's because at 60 GHz, all techniques will need to focus signals between two devices that want to communicate.
"We have run two 60-GHz networks in the lab without any interference problems," he said.
In addition, the .3c draft implements a 50-Mbit control channel so terminals can negotiate use of 60-GHz channels to avoid interference. The ad hoc Wireless HD protocol also supports using this so-called Common Rate control channel.
Two Japanese organizations helped draft the .3c spec: the National Institute of Information and Communication Technology and the Consortium of Millimeter-wave Practical Applications. The latter group is developing prototype 60-GHz terminals that will go into field tests soon.
Shinko Maekawa, editor of EE Times Japan, contributed to this report.
