ViaSat is making it clear: Both the satellite interests and 5G stakeholders need to work together in order to facilitate shared use of 27.5-28.35 GHz and the 37.5-40.0 GHz bands.
That sentiment, outlined in a recent filing with the FCC, echoes a message that FCC Chairman Tom Wheeler delivered in March when he said "this is very much a two-way street," in terms of the need for satellite and mobile industries to work out spectrum sharing solutions in the higher-band spectrum that is being eyed for 5G.
In April, Verizon (NYSE: VZ), Qualcomm (NASDAQ:QCOM), Nokia (NYSE:NOK), Samsung Electronics America, Intel and Ericsson (NASDAQ: ERIC) filed an ex parte with the commission urging the FCC to increase maximum allowable base station power levels from the proposed 62 dBm to 75 dBm EIRP per 100 MHz. They said the proposed level of 62 dBm results in a much lower spectral density than is achievable in other mobile bands. "Because the power will be spread over more megahertz in the Upper Microwave Flexible Use Service, the range of base stations would be much smaller than with similar power levels in existing mobile bands," the companies said.
In response, ViaSat said in a filing this week that any given proposal for 5G operations likely affects one of four interference paths that must be analyzed and addressed in order to ensure successful sharing between 5G and satellite services in the same spectrum band. Those paths, as ViaSat outlined, are:
- Path 1: 27.5-28.35 GHz---Aggregate emissions from 5G base stations and user devices in the Earth-to-space direction into the uplink receivers at the satellites
- Path 2: 27.5-28.35 GHz---Emissions from satellite uplink earth stations into 5G base stations and user device receivers on the Earth
- Path 3: 37.5-40.0 GHz---Emissions from 5G base stations and user devices into satellite downlink earth stations on the Earth
- Path 4: 37.5-40.0 GHz---Emissions from satellite downlinks from space into 5G base stations and user devices on the Earth
ViaSat says the suggestion by Verizon and others to increase the power level of 5G base stations and semi-stationary moveable devices above that proposed in the FCC Notice of Proposed Rulemaking (NPRM) affects Path 1. In addition, the 5G parties' proposal "does not take into account or even acknowledge" that the 27.5-28.35 GHz band segment currently is shared with satellites that have been designed in reliance on the existing designated uses of the band. Nor does the 5G proposal acknowledge that the commission "clearly intends that the terrestrial mobile systems sharing criteria be developed by taking satellite network operations into account."
ViaSat's primary concern the with 5G players' proposal is not the proposed 5G power level in and of itself, "but rather is (i) the absence of any stated plan or mechanism for managing the aggregate unwanted energy that will be directed toward space and the resulting unwanted energy arriving at a satellite's location under Path 1, and (ii) the likely resulting harmful interference to satellite receivers under Path 1."
The satellite company also says the technical analysis that it submitted into the record on April 21 provides significant detail about the aggregate unwanted energy from 5G transmissions that satellite receivers can tolerate. Proposals also must take into account the effect of possible forward scatter from dense metallic objects near 5G transmitters, such as a dense group of automobiles, ViaSat says.
Based on ViaSat's closing paragraph, it appears it's not feeling the love from mobile players. "ViaSat is involved in ongoing technical discussions and committed to working with the Commission and all parties to explore potential sharing solutions that will promote deployment of 5G alongside existing and future satellite networks in the 27.5-28.35 GHz and 37.5-40.0 GHz bands," the company said. "Some solutions may require innovative antenna technology or other sharing techniques for the 5G operations, but because of the long lead time for 5G deployment, there is time for flexibility of 5G network designs. ViaSat is open to considering such approaches but needs the 5G Parties' engagement as well."
ViaSat isn't the only satellite company complaining about a lack of meaningful dialog. O3b also recently told to the FCC that while some spectrum sharing discussions are underway, "engagement has been uneven."
- see this ViaSat filing
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