FCC Clarifies Rules for U-NII Devices

Erin Bradford

Adelstein

FCC has issued a memorandum and order to respond to requests for clarification of its rules for Unlicensed National Information Infrastructure (U-NII) devices in the 5.25–5.35 GHz and 5.47–5.725 GHz bands. These devices include radio local-area networks (RLANs). In the document, the commission granted a request to clarify the transmit power control (TPC) requirements in section 15.407(h)(1) and issued a revised measurement procedure for certifying U-NII devices for compliance with the dynamic frequency selection (DFS) requirements in those bands.

“This [memorandum and order] marks the beginning of a significant new phase in the development and deployment of wireless broadband services,” said Commissioner Jonathan S. Adelstein in a statement. “It paves the way for the authorization of devices to use an additional 255 MHz of spectrum in the 5 GHz band, a significant increase in spectrum capacity for unlicensed uses.”

FCC also denied a request to revise the rules to state that U-NII devices would not be required to detect and avoid frequency-hopping radar signals. It also dismissed requests to clarify the channel availability check time requirement and to modify the definition of a U-NII central controller that must include a DFS capability (see Table I).

Table I. Applicability of DFS requirements during normal operation.

Operation in the newly available U-NII spectrum is conditional upon compliance with certain technical requirements. The rules require that U-NII devices operating in the 5.25–5.35 GHz and 5.47–5.725 GHz bands employ DFS to avoid causing interference to federal government radar systems. DFS monitors the spectrum and selects a frequency that is not already being used.

In addition, the rules require U-NII devices to employ a TPC mechanism when operating in those bands to further protect operations in the Earth Exploration Satellite Service and the Space Research Service. TPC adjusts a transmitter’s output power based on the signal level present at the receiver. As the signal level at the receiver rises or falls, the transmit power will decrease or increase as needed.

FCC has also provided an interim measurement procedure to be used in determining whether U-NII devices comply. The International Telecommunication Advisory Committee-Radiocommunications Government/Industry Project Team developed revised measurement procedures for performing DFS compliance measurement tests for U-NII equipment. The revised procedure includes modified definitions, technical requirements (e.g., detection thresholds and new response requirements), radar test waveforms, test procedures, and test report guidelines.