WIRELESS DEVELOPERS BEGIN EYEING 90 GHz, PENDING SERVICE RULES

FCC’s Office of Engineering & Technology held forum last year on 90 GHz technologies, seeking feedback on potential commercial uses in 92-95 GHz. To date, 77 GHz is highest band for which service rules exist. At the time, Commission officials said notice would explore issues such as whether spectrum should be allocated on licensed or unlicensed basis. Although 90 GHz band isn’t used heavily, mostly military applications are authorized to operate in band, which gives NTIA interest in spectrum-sharing issues. Developers describe potential transmission range above 90 GHz as more closely resembling 40 GHz band, rather than very short transmission range of 59-64 GHz. WCA said equipment providers were eyeing radios with 1 bit per Hz modulation formats that could offer transmission speeds at 1 Gbps for streaming video, massive software files and other last-mile access applications.

WCA Engineering Task Force for Spectrum Policy Above 40 GHz has been developing guidelines for FCC for allocation of 90 GHz band for commercial use. Endwave Exec. Vp Douglas Lockie, who is co-chairing task force, said industry recommendations floated to FCC have included drafting service rules on technology-independent basis that “allows industry to innovate.” He also is co-founder of Endwave, which develops radio frequency subsystems for broadband wireless systems, including products for high-speed cellular backhaul and point-to-point and point-to-multipoint access applications. Industry group recommended that effective isotropic radiated power levels be modeled after 38 GHz and 28 GHz LMDS rules. Panel also is suggesting that 5-10 GHz in band be opened to commercial uses, rather than just 92-95 GHz that originally was under consideration at FCC. “A number of us on the committee feel that the real market for this higher frequency and potentially broader bandwidth is connectivity computer-to- computer,” Lockie said. Key advantage for fixed wireless point- to-point radios in such bands is offering very high data rates to hook local area networks into metropolitan area networks and into wide area network, he said: “This is backbone or local access to break the bottleneck.” Panel didn’t reach consensus on preference for licensing point-to-point operations in spectrum, putting it out to auction or making it available on unlicensed basis, Lockie said. He and other industry participants said one possibility would be hybrid approach in which some spectrum would be licensed and other blocks in band would be unlicensed. Still unclear was whether, even if spectrum were licensed, it would be put out for bid.

Alternating licensed and unlicensed blocks in band would allow unlicensed segments to perform guardband function because systems would operate there at lower power. That particularly is case because spectrum below 92 GHz is allocated for passive uses, such as aviation imaging systems, and guardband between licensed and unlicensed blocks could offer protection to that lower band. Allocation of 86-92 GHz for passive systems and other systems that might be safety related makes it important to limit out-of-band emissions in that spectrum, FCC said in paper presented last month at symposium on millimeter waves in Yokosuka, Japan. Creating need for coordination with NTIA in 92-95 GHz is existence of military research projects in band. Thus service rules must consider sharing with other federal agencies, FCC paper said. Presentation also said that because narrow beam antennas appeared to be feasible in 92-95 GHz, it made possible unique method for multiple point-to-multipoint systems to share common frequency block in same geographic area. As result, base stations might be able to operate on separate offset grids and users could then select network for service by pointing antenna. One regulatory scenario for implementing such sharing might be use of Commission’s recent secondary market policy statement. FCC paper said that could mean that licensees would be given right and ability to negotiate privately with other companies to develop sharing arrangement.

Major attraction of 90 GHz band is that there is “tons of spectrum available,” said Peter Jarich, dir.-global broadband research for Strategis Group. Through low-order modulations with relatively inexpensive equipment, high data rates are possible, he said. Among trade-offs of licensed vs. unlicensed question is that with licensed spectrum, equipment vendors have incentive of clearly targeted audience to develop systems for, Jarich said. “If there are no licensees, who do they target -- is it a bunch of operators with no money?” he asked. But benefit of spectrum being made available on unlicensed basis, Jarich said, is that it could spur more companies’ getting into market “who haven’t just blown a whole lot of money on auctions.”

One advantage of allocating at least 5 GHz in band is that it opens possibility to “the 10 gigabit types of services well down the road,” said Burt of e-xpedient/CAVU. “Having more spectrum would allow more channelization and more opportunities for other players in this space.” Properties of 90 GHz band are similar in many respects to spectrum at 38 to 40 GHz, where channel plans allow 100 Mbps of capacity to be offered, he said. At 94 GHz, same coverage distances can be offered, but gigabit ethernet can be deployed, Burt said. While higher data speeds can be offered in interim bands such as 60 GHz, this band is unique because it’s in middle of oxygen absorption band, so it’s tailored to short distances, such as hops between buildings in urban areas, Burt said. But at 90 GHz, distances 2 to 3 times greater than those possible at 60 GHz can be offered, Burt said.

Telaxis CEO John Youngblood also stressed importance of rules not just replicating policies for lower bands of spectrum such as 38 GHz. “It’s a whole different world,” he said of spectrum above 90 GHz. Youngblood said Telaxis would like to see large band of spectrum made available, even in 96 to 112 GHz range. “We would not like to see it broken up into small channels,” he said. “The type of technologies being used at higher frequencies take advantage of the fact that there is a lot of bandwidth up there.”