Siding with CTIA, Google (NASDAQ: GOOG) is urging the FCC to reject satellite industry claims about potential interference in the 3.5 GHz band and allow network operators to deploy higher power devices when sited in clutter.
CTIA in October of last year urged the commission to reject proposals by the Satellite Industry Association (SIA) that would "unnecessarily limit out-of-band emissions (OOBE) limits and power levels and thereby significantly restrict wireless broadband" in the 3.5 GHz band. CTIA said it wants to help ensure the wireless industry has the incentive and ability to invest in the 3.5 GHz band.
The satellite industry, however, has other ideas. It's concerned that Citizens Broadband Radio Service (CBRS) devices in the 3550-3700 MHz band will disrupt primary Fixed Satellite Service (FSS) operations in this and adjacent spectrum, and it's asking the FCC to adopt stricter measures to protect FSS from CBRS interference.
Google takes issue with some of SIA's reasoning, saying the SIA "makes the unremarkable observation that 'peak emissions can have significant interference effects.' It is logically inconsistent, however, for SIA to ask the Commission to characterize interfering emissions by their peak amplitude, while not characterizing the system noise level of FSS earth stations in the same fashion," Google told the commission. "Characterizing interference effects based solely on peak emissions would depart from Commission precedent as well."
All signals, including LTE, Wi-Fi, WiMAX – and even Gaussain thermal noise – will have statistical variations in the instantaneous amplitude of the waveform, Google says. For this reason, neither cellular, PCS, AWS nor 700 MHz emissions are measured using peak hold. Moreover, "comparing LTE signals to Gaussian thermal noise illustrates the absurdity of SIA's position. The peak-to-average ratios and signal statistics of LTE and Gaussian thermal noise are generally similar, and thermal noise is typically evaluated using mean measurements. Because the characteristics of these two types of emissions are similar, the measurement of their interference potential should be treated the same."
For handy reference, Google included in its FCC fling this definition of Gaussian thermal noise: It's the noise attributed to natural random power fluctuations due to the thermal motion of molecules, atoms and electrons.
CTIA has asked the FCC to move to relax proposed emission limits for 20 megahertz-wide channels in order to enable more robust use of the 3.5 GHz band. It also wants the FCC to revise stringent OOBE limits at the band edges, which it says are unnecessary to protect adjacent-band services.
Generally speaking, Google said the FCC's April 2015 Report and Order adopting rules for expanded use of the 3.5 GHz band struck a reasonable balance between the interests of existing federal and commercial users and the needs of new entrants.
But the satellite industry has been raining on the 3.5 GHz parade, saying CTIA, Nokia (NYSE:NOK), Verizon (NYSE: VZ) and WinnForum all advocate "across-the-board" increases in the maximum power for each category of CBRS devices. SIA argues that higher power levels necessarily will require greater protection distances to prevent interference to FSS earth stations and other incumbent networks.
- see this Google filing
Google, Intel, Nokia and more partner to advance U.S. 3.5 GHz CBRS
Google seeks clarification on SAS rules for 3.5 GHz band
Federated Wireless marks milestone in spectrum sharing platform