FCC URGED TO FINE-TUNE PROPOSAL FOR UNLICENSED DEVICE RULES

To bolster the availability of broadband wireless technologies through more efficient spectrum sharing, the FCC in Sept. proposed updates in some of its Part 2 and Part 15 rules for unlicensed devices. The proposal would: (1) Allow use of advanced antenna technologies with spread spectrum devices at 2.4 GHz and alter the replacement antenna restriction for Part 15 devices. (2) Update equipment authorization procedures to allow more flexibility to configure transmission systems without requiring separate authorizations for every combination of system components. (3) Harmonize measurement procedures for digital modulation systems under Part 15 and change channel spacing requirements for frequency hopping spread spectrum devices at 2.4 GHz to remove hurdles to the introduction of new technologies using wider bandwidths. (4) Spell out equipment authorization requirements for modular transmitters.

Microsoft urged the Commission to adopt unlicensed sharing rules in new bands where those devices would be used for broadband data networks. The FCC has stipulated the obligations of unlicensed devices to protect licensed services but has been reluctant to weigh in on conflicts among unlicensed services, it said. Spectrum etiquette among unlicensed devices now is critical, Microsoft said. The proposal sought comment on such an etiquette, based on 1.9 GHz unlicensed PCS rules that require devices in that band to monitor the spectrum and transmit only when no signal above a particular threshold is detected. Increased use of unlicensed spectrum for critical wireless networks and the evolution of such devices toward higher bandwidths has shown that current rules “systematically favor narrowband devices over broadband devices since the latter devices encounter more difficulty in finding an open channel in which to operate,” Microsoft said. As an example of systems that could use new technology to exploit unregulated public networks, Microsoft cited the “Wi-Fi Hog” developed by MIT. That system consists of a laptop linked to different sniffing and jamming devices that can take “complete control” of a public Wi-Fi network by blocking other users, Microsoft said.

Microsoft called for rules to compel unlicensed devices, especially in more crowded lower bands, to use spectrum more efficiently. It called for unlicensed devices: (1) To observe a “non-greedy occupancy” rule for spectrum sharing, meaning no user should occupy any channel when it had no data to send. (2) To refrain from transmitting on a particular channel unless they could do so without causing harmful interference to devices already operating there. It said that could be done through an “interference threshold,” which would be the aggregate interference level that could be sensed by a network node at which the node must consider that channel unavailable. That would be band-specific and based on the actual interference environment. (3) To incorporate a minimum amount of dynamic range and “to reduce transmit power to the minimum necessary to achieve the link margin they desire.” Microsoft said the proposed rules were “framed as performance requirements rather than as design specifications.”

Intel argued that spectrum sharing etiquettes weren’t necessary right now. “Today’s sharing allocations are successful because they create a structure of primary and secondary users and give de facto control of the secondary use to the owner of the immediate physical area (business, campus or home),” it said. Attempts by the FCC to mandate etiquettes in that area probably would delay the rollout of new services and impede innovation, Intel argued. Crowding problems that could be expected from “co-equal” unlicensed devices have been mitigated, it said, citing Wi-Fi deployments in which a homeowner controls the deployment of such devices. It told the FCC that while there was a need for some boundaries around the beamwidths of advanced antenna technology, a minimum beamwidth of 120 deg. wasn’t the best scenarios for all cases. The Commission sought feedback on the characteristics a system would need to exhibit to be classified as a sectorized or phased array antenna system and proposed limiting the total simultaneous beamwidth radiating from an antenna to 120 degrees.

Motorola said that for now it didn’t back a spectrum etiquette for unlicensed bands outside 1.9 GHz unlicensed PCS spectrum. “The risk that a spectrum etiquette may stifle innovation and product development outweighs any apparent benefits,” it said. Motorola said such sharing rules weren’t needed at 2.4 GHz. “While such an etiquette may be appropriate in future bands available for unlicensed operations, depending on the circumstances, the lack of an etiquette in current bands has allowed innovation and should not be altered at this time,” it said.

Citing recent changes in Part 15 rules to accommodate new digital technologies, Cisco argued against having 2 sets of rules apply to identical devices operating in virtually identical spectrum. It urged the FCC to adopt a single measurement procedure for digital modulation systems in the Unlicensed National Information Infrastructure (U-NII) band. It said the FCC proposed that unlicensed digitally modulated systems operate under unlicensed rules at Part 47 of Sec. 15.407 of the Communications Act or under spread spectrum rules in Sec. 15.247. The Commission earlier had altered its spread spectrum rules to accommodate devices that used the advanced digital modulation techniques already allowed by the U-NII rules. “As a result of these rule changes, identical unlicensed devices can now operate in the same spectrum under 2 different sets of rules,” Cisco said. The FCC had noted that different measurement procedures applied to those 2 rule sections, which meant the 2 sections could treat identical devices operating in identical spectrum differently. Cisco backed the FCC proposal to apply the compliance testing procedures of Sec. 15.407 to the authorization of devices under the spread spectrum rules of Sec. 15.247.

Hewlett-Packard told the FCC it generally supported the proposed new rules on advanced antenna technologies but had concerns about the interference risk to “normal” users and access point devices on Wi-Fi networks. H-P reflected concerns of several other commenters, saying the FCC’s Part 15 rules had been successful but offered no protection against interference to unlicensed devices. H-P suggested some additional controls or guidelines, such as location and frequency restrictions, to keep interference from “eventually becoming a problem.” It singled out the advanced antenna systems for point-to-multipoint service, which it said clearly would have increased power density at the intended receiving points compared with devices with omnidirectional antennas. “Point-to-multipoint services with steerable or sectored antenna beams and relatively higher power may present an unacceptable level of interference to regular users of 802.11 WLAN [wireless local area network] systems,” it said. H-P said that represented a different interference risk than fixed point-to-point services where the interference potential was limited to fixed locations. To help control interference, H-P suggested restricting the operation of point-to-multipoint systems to certain sub-bands or frequencies, “perhaps with some geographical overlay.” That would keep other frequencies available for normal WLAN use, it said.

The Consumer Electronics Assn. (CEA) lauded the proposals to allow use of phased array and adaptive sectorized antennas, saying that would bolster the reliability of communications carried by unlicensed devices and increase spectrum efficiency by letting the signals be directed toward the devices “with which the communication is desired and away from other devices and users.” CEA called for the FCC to extend those provisions to other unlicensed bands, including bands at 5 GHz. It also backed proposals to let professional installers and service providers customize their systems with different antennas and to use amplifiers of up to 1 W when that power level was permitted. Such changes would promote wireless broadband access, CEA said. It urged the FCC not to consider spectrum etiquettes for unlicensed bands beyond unlicensed PCS spectrum at 1.9 GHz. In the unlicensed PCS spectrum, equipment and services failed to flourish, despite the prime location of that band, CEA said. “This stands in marked contrast to the success of a wide variety of unlicensed devices in the unlicensed bands neighboring the UPCS bands,” it said. CEA recommended against spectrum etiquettes except in “very narrow circumstances where specific methods are required to protect a primary user in the same band.”

The Technology Industry Council (ITI) backed the proposed streamlining of antenna approvals under Part 15 and said the changes wouldn’t increase interference to other services in that unlicensed band or adjacent frequencies. But ITI objected to the FCC’s proposed requirement for unique antenna connectors, saying multiple radio vendors would use the same connectors to reduce cost. The group said the requirement shouldn’t be applicable to the unlicensed devices covered by those rules. The requirement adds additional costs for the end user “with no demonstrable benefit,” it said. ITI also raised concerns about the extent to which FCC rules required unlicensed devices to accept interference from other unlicensed devices, some of which were serving as “last-mile” broadband networks. “A challenge for policymakers is to ensure that the interference environment permits unlicensed broadband devices to operate with great reliability,” ITI said.