HOW TO MAKE WAY FOR WI-FI AT 5 GHZ TEED UP FOR WRC DEBATE

U.S. and industry interests are trying to strike balance between protecting existing military radars in that band and making way for harmonized spectrum at 5 GHz for Wi-Fi. How to make way for Wi-Fi at 5 GHz is shaping up as one of more contentious issues on next year’s WRC, several sources said.

Before Conference Preparatory Meeting (CPM), industry, NTIA, Defense Dept. and FCC had been discussing possible protection levels that would work. One source said process was “cut short” when time ran out and U.S. govt. position backed limitations sought by DoD. “Discussions are still supposed to go on,” source said. “Industry and DoD were pretty close on workable protections,” source said, and both agreed that protections were required and should be carried out through mechanism called dynamic frequency selection to avoid interference: “It’s come down to what are the sensitivity levels required to provide DoD protection.” Companies still are analyzing maximum protection levels that could be provided while allowing for wireless LAN deployment of systems such as Wi-Fi, he said. One concern of some U.S. companies is that protection levels in Washington proposal are so low “that you will get a lot of false positives and systems will think that a radar is there, even it if isn’t, and not be able to use those frequencies,” source said.

“Very active” technical discussions have taken place by govt. and industry engineers on that issue since May, although talks were on hiatus while the CPM in Geneva and recent Inter-American Telecommunications (CITEL) meeting in Buenos Aires were taking place, NTIA Deputy Dir. Michael Gallagher said. He told us he expected participants to be back at table at beginning of next year to gear up for WRC. “We look forward to continuing the dialog,” he said, and DoD has given its commitment to participate in those talks.

U.S. also is “actively engaged” in dialog with other countries that use same or similar systems as DoD is concerned about at 5 GHz to gain their support at WRC, Gallagher said. He declined to elaborate on which military systems U.S. had in common with other countries in that spectrum, saying some of systems in band were part of classified programs. There are about 8 military radar systems in band to be protected from wireless LAN use. To evaluate measures to prevent interference, NTIA took most sensitive system in that band and “said if you protect that radar you have protected the rest,” Gallagher said. Industry and govt. engineers have been looking at technical criteria targets, he said. “They have been working through the technical needs of the radars and the technical capabilities of the devices that would be deployed in the band,” Gallagher said. One reason U.S. position, for now, is not in line with that of other administrations is that U.S. has far more extensive systems to protect in that band than do other countries, he said. He said there still are several months before the start of WRC, and positions still are being developed. “We're at the halfway point. The game isn’t over,” he said.

Still, pending U.S. proposal has bumped up against less- restrictive measures that regulators in Europe, Canada and Brazil would like, several sources said. Proposed alternatives on this agenda item that emerged from the preparatory meeting said dynamic frequency selection (DFS) could provide uniform loading of wireless LAN channels across 5 GHz spectrum, although studies have shown that mitigation effect of that technology was reduced according to available bandwidth. DFS allows detection and avoidance of co-channel interference with radar systems. CPM documents offered several methods for addressing 5 GHz agenda item at WRC. U.S.-backed option was Method D -- primary global allocation to the mobile service in 5150-5350 MHz, including mitigation techniques that still were under study. It would postpone resolution to continue consideration of wireless LAN deployment in 5470-5725 MHz until WRC 2007. Proposal would include footnotes or resolution on how to protect existing services in lower band. While advantages listed as part of that alternative included allowing some initial deployment of wireless access service (WAS), CPM paper said “this method does not fully respond to the need for globally harmonized spectrum for WAS,” including wireless LANs. By putting off decision on 5470-5725 MHz, only 200 MHz was included in this proposal, which could limit the rollout of wireless LAN technologies, CPM paper said. It said that although “some administrations” believed same sharing conditions between wireless access systems and radar systems applied in 5250- 5350 MHz and 5470-5725 MHz bands, “this method treats the 2 bands differently.”

Among other potential disadvantages, CPM document said administrations might permit license-exempt use in 5470-5725 MHz “without the benefit of mitigation techniques specified by the ITU.” That method also could increase congestion of devices in lower band, 5150-5350 MHz, which could lead to more aggregate interference to existing services such as fixed satellite service in the band, it said. It said that if space science services allocation was made at 5470-5570 MHz at WRC 2003, that “may prejudice a possible allocation to the mobile service in the band 5470-5725 MHz at WRC-07,” CPM paper said. It also said U.S.-backed method wouldn’t provide allocation for fixed service at 5250-5350 MHz, which could lead individual administrations to move forward with their own operations and create interference “from aggregate effects from a large number of devices for which no single administration is responsible… Remedial action could therefore be difficult to achieve, particularly with respect to protection of satellite systems.”

Each of 4 methods in CPM report listed advantages and disadvantages, but drawbacks of U.S. approach were particularly long, several sources said. List of those drawbacks “in the view of many was devastating to the U.S. position” but was required to get that approach adopted as part of CPM report, source said. Footnote language addressed application of DFS in lower band, saying one administration - - meaning U.S. -- supported that technical decision. In WRC arena, “that stands out in that you almost never see something supported by [just] one administration,” source said. “No one but the U.S. thinks that,” industry source said. “The U.S. got its position incorporated. On the other hand, it did so in such a way that it has little chance of success at the WRC” in its present form, source said.

Version of European proposal would be more amenable to U.S. private sector for allowing Wi-Fi and similar systems to grow at 5 GHz with global allocation, several sources said. “International allocation is a good thing for the private sector because most administrations all around the world will conform to it and one can build equipment that will be useful anywhere in the world. The economies of scale dramatically reduce the cost of that equipment,” industry source said. Guidance document by European Conference of Posts & Telecommunications on 5 GHz item released this fall would designate 5150-5350 MHz and 5470-5725 MHz for wireless LAN allocation, using interference mitigation techniques such as DFS and transmitter power control. Brazil also has backed proposal in this area that would be much more favorable to radio LAN industry, and Canada is backing separate alternative, further complicating support for U.S. position, another source said.

“DoD played a very strong hand in getting a U.S. position,” industry source said. While this could be starting point for negotiations going into WRC, another source noted that this strategy could backfire if conference ultimately adopts another proposal, leaving DoD military systems without protection in other parts of world.

“There are still active discussions going on between the private sector and the U.S. government over the ability of radars and unlicensed devices to share the 5 GHz spectrum,” said Washington attorney Scott Harris. “I continue to believe that there will be agreement between the private sector and the U.S. government before the WRC on the best way both to protect radars and to allow for the expansion of unlicensed services at 5 GHz.”

Another source following development of U.S. policy acknowledged that 5 GHz agenda item had been “contentious,” with European administrations generally “insistent” on approach that would allow global allocation up to 5725 MHz at WRC 2003, rather than deferring decisions on upper band until 2007, source said.

In Sept., Senate Commerce Committee Chmn. Hollings (D- S.C.) wrote to FCC, NTIA and Defense Dept., urging them to craft U.S. stance for WRC that would consider international allocation of entire 465 MHz at 5 GHz for use by unlicensed broadband networks. Wireless Ethernet Compatibility Alliance submitted analysis to FCC this fall on impact of deployment of radio LANs at 5 GHz, concluding that sharing between RLANs operating in mobile service and radars in radiolocation service was feasible. During formation of U.S. policy, however, NTIA had raised concerns about differences in sharing between wireless access service and existing services at 5 GHz, disagreeing with proposal developed by WRC Advisory Committee at FCC.