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Tuesday, August 23, 2011

FCC publishes new draft testing guidelines for U-NII devices

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Public comment is now open, until September 23, 2011, on the FCC guidelines for testing Unlicensed National Information Infrastructure (U-NII) devices, in accordance with CFR 47 Part 15, Subpart E.

In addition to the measurement standards called out in section 15.31, and ANSI C63.10, these guidelines will form the general test procedures for testing all U-NII devices for compliance with the technical requirements of section 15.407.

The U-NII radio band is an unlicensed band divided into three spectrum segments in the 5GHz range, 5.15–5.35 GHz, 5.47–5.725 GHz and 5.725–5.825 GHz. U-NII devices use wideband digital modulation techniques, and provide a wide array of high data rate mobile and fixed communications for individuals, businesses, and institutions. Examples are 802.11a devices.

Dynamic Frequency Selection (DFS) functions, which are required between 5.25 – 5.35 GHz and between 5.47 – 5.725 GHz for the protection of government radar systems, are covered in a separate document. See FCC Order, ET Docket No.03-122 (FCC 06-96).

For devices that transmit on multiple outputs simultaneously such as MIMO and beam forming technologies, FCC KDB Publication Number 662911 also applies.

The new guidance replaces Public Notice DA 02-2138 of 8/30/02 and contains the following changes;

  • The document interprets and clarifies the language of 15.407(a)(4) (maximum conducted output power)
  • Revises the spectrum analyzer-based methodologies for measuring maximum conducted power and provides an option to use an RF power meter
  • Revises the methodologies for measuring Peak Power Spectral Density (PPSD) to match those used to measure maximum conducted output power
  • Specifies the use of max hold when measuring Emission Bandwidth (EBW)
  • Defines compliance with 15.407(a)(6) (peak excursion) in terms of the ratio of maximum of the peak-hold spectrum to the maximum of the average spectrum—eliminating the need to compute the ratio at each frequency (a process that had resulted in unintended failures near band edges)
  • Adds guidance for measuring unwanted emissions.  The guidance interprets the non-restricted band limit as a peak limit and restricted band limits as including both average and peak limits.  Both restricted and non-restricted band limits are based on continuous transmission with no subsequent reduction for operational duty cycle.  The guidelines permit both restricted and non-restricted band compliance be demonstrated by radiated measurements or by antenna-port conducted measurements combined with radiated cabinet emission measurements.

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