FCC Aims to Open up 6 GHz Band for Unlicensed Use While Protecting Incumbents through Automated Sharing Features and Other Restrictions
5.925-6.425 and 6.525-6.875 GHz: Automated Frequency ControlUnlicensed devices using the 5.925-6.425 GHz and 6.525-6.875 GHz sub-bands would be able to operate both outdoors and indoors at power levels permitted for unlicensed use in the U-NII-1 and U-NII-3 sub-bands (5150-5250 and 5725-5850 MHz, respectively). But the NPRM envisions that unlicensed devices in the 6 GHz sub-bands labeled U-NII-5 and U-NII-7 by the draft item would only be allowed to transmit if an automated frequency control (“AFC”) system determines that such transmissions are permitted, so as to avoid harmful interference to licensed operations. The AFC system, or systems, would communicate with an unlicensed device that acts as a “standard-power access point,” which, in addition to operating itself, would control operational permissions for client devices as well as devices accessing a wireless router in the home or an access point at a public location. The draft item notes that the U-NII-5 and U-NII-7 sub-bands are home to point-to-point microwave links that support public safety, railroad, oil and gas pipeline, utilities, and wireless and wireline communications service, as well as some fixed satellite services. As the fixed service incumbents are at known, fixed locations, the FCC believes the AFC system could be a “simple database” which is automatically queried to determine which frequencies are available for an unlicensed device to use at a given location and time. The FCC seeks comment on numerous aspects of possible approaches to the AFC system concept, thereby highlighting the many technical and other issues that will need to be resolved. These include what are the basic eligibility requirements to be an AFC system operator; whether there should be more than one AFC system; whether the FCC’s ULS system is or can be made sufficiently reliable as the basis for AFC system operation and determination of available frequencies; whether and how AFC systems (assuming there are more than one) will need to exchange data; whether the AFC system(s) should be centralized or de-centralized; whether unlicensed devices will need to register with the AFC system(s) and will need to identify themselves to incumbents; how the location and height of an unlicensed 6 GHz Band device will be determined before frequencies are selected; what security needs to be in place to ensure proper operation of the AFC system(s); whether 6 GHz Band unlicensed devices might cause aggregate harmful interference to satellite space station receivers and, if so, how to mitigate that interference; how often unlicensed devices would need to check the AFC system to confirm the availability of the frequencies they are using; and whether and how AFC system operators can charge access fees. The FCC also requests input on the nature of and metrics for the appropriate interference standard to protect incumbent licensees, ensuring that unlicensed devices in the U-NII-5 and U-NII-7 sub-bands cannot operate co-channel to any fixed link within that link’s defined exclusion zone. In this area, the Commission faces a number of “real-world” challenges, such as properly allowing for multipath fading when an AFC system determines that a frequency is available, with the goal of maximizing spectrum utilization by licensed and unlicensed devices.
6.425-6.525 and 6.875-7.125 GHz: Low-Power, Indoor OperationMeanwhile, unlicensed devices using the 6.425-6.525 GHz and 6.875-7.125 GHz sub-bands, which the NPRM terms the U-NII-6 and U-NII-8 sub-bands, respectively, would only be allowed to transmit indoors and at lower power levels than in the U-NII-5 and U-NII-7 sub-bands (equal to the same, more restricted, power levels already applicable to the 5 GHz U-NII-2 bands (i.e., 5250-5350 and 5470-5725 MHz)). However, as the draft NPRM would propose, unlicensed operations in the U-NII-6 and U-NII-8 sub-bands, by “low-power access points” and client devices, would not be subject to AFC system coordination before operation. The draft NPRM states that this sub-band is primarily used for mobile such as Broadcast Auxiliary Service television pick up stations (i.e., electronic news gathering and wireless video links), mobile and fixed Cable Television Relay Service links, several varieties of fixed television-service-related links which operate on a more restricted basis, licensed wireless microphone operations, and a limited number of satellite services. The itinerant operations of the foregoing mobile services make the use of an AFC system infeasible. The FCC inquires how indoor use effectively can be assured, asking, for example, whether it should adopt specific equipment restrictions to ensure indoor operations (e.g., requiring devices to have a direct connection to a power outlet) and how to address potential interference complaints.
Interference MitigationThe FCC’s draft item proposes a number of interference mitigation measures and potential limitations on unlicensed device use, indicating an openness to outside recommendations on how to best strike the balance between unlicensed and licensed use of the band. For example, would AFC system(s) permit operations on certain frequencies but at lower powers, whereas operation would be precluded if the unlicensed device’s maximum power were used to determine available frequencies? In addition, the NPRM would propose client devices be allowed to connect with both standard-power access points and low-power access points, and be permitted to operate across the entire band which should encourage the widespread availability of client devices. Similarly, to promote widespread adoption, the draft NPRM would also inquire whether there are ways to allow higher power and even outdoor operations in the U-NII-6 and U-NII-8 sub-bands without causing interference to mobile operations. Conversely, the Commission intends to ask whether non-AFC system operations by low-power access points should be permitted in the U-NII-5 and U-NII-7 sub-bands. Finally, the NPRM would propose to preclude operation of standard-power and low-power access points in moving vehicles, cars, trains, or aircraft (and implicitly raises the question whether sufficient spectrum is available for unlicensed operations in moving vehicles, in addition to certain 60 GHz unlicensed operations on aircraft pursuant to Commission decisions in the Spectrum Frontiers proceeding). The adoption of the NPRM would provide an opportunity for all stakeholders to weigh on the future use of the 6 GHz Band.
Tags: 5G, 6 GHz Band, automated frequency control, Broadcast Auxiliary Service, cable, Cable Television Relay Service, FCC or Federal Communications Commission, Internet of Things, IoT, LTE-U, Mobile, Spectrum, Spectrum Frontiers, U-NII, Unlicensed National Information Infrastructure, Wi-fi, Wireless