Straight Path says Boeing's 5G technical analysis is flawed

Straight Path, which owns spectrum licenses in the 28 GHz and 39 GHz bands that once belonged to Winstar, is calling out the Satellite Industry Association (SIA) and Boeing for what it says are bogus claims about the 37/39 GHz band.

"SIA argues that it has 'identified the 37/39 GHz band as key to future FSS deployments where the record is incomplete.' Boeing similarly claims that it is 'developing' a satellite network that requires use of the entire V-band," Straight Path CEO and President Davidi Jonas wrote in an FCC filing. "As Straight Path has already pointed out, however, the claim that the 37/39 GHz band is 'key to future FSS deployments' or that a satellite network is being developed in some unspecified time frame is belied by the facts."

"In fact, the satellite industry has made no use of the 37/39 GHz band and has done nothing to seek any imagined regulatory changes necessary for additional use. Moreover, the record in this proceeding supports use of the bands as the Commission proposed. If SIA or others thought alternative uses of the bands were appropriate, they already had ample time to offer their suggestions," he said.

Boeing in several ex parte filings with the commission presented interference analyses between fixed satellite systems (FSS) and 5G in the 37/39 GHz band. However, according to Straight Path, these analyses were based on flawed assumptions that naturally led to incorrect conclusions.

For one thing, Boeing's analysis assumes 5G base stations will suppress satellite interference by 20 dB such that the satellite interference to 5G uplink will be limited. That assumption is "restrictive and would prohibit contemplated 5G deployment scenarios," Jonas said, referencing what he considers a more accurate assumption derived from antenna patterns for frequencies above 6 GHz agreed in 3GPP.

For another, Boeing also argued that Straight Path did not provide technical support for the statement that 5G systems "are more susceptible to interference from satellites than current point-to-point links with fixed narrow beams along the horizon," which Straight Path says ignores the "well-known fact that point-to-point links use high-gain dish antennas with small side lobes. When pointing along the horizon, these antennas have good suppression of interference from satellites at large angles above the horizon.

However, the phased-array antennas used by 5G base stations can steer within a large angle. In some cases, the beamforming algorithm may find it advantageous to steer the main beam upwards, e.g., to users in nearby high-rise buildings or to exploit a diffraction path across a roof or tree top to get to a non-line-of-sight user. "These beams would be significantly affected by satellite interferences under Boeing's proposal," he said.

Boeing in a June 7 filing said Straight Path provided no technical showing to support its claim about the likelihood of interference but indicated that it would review any such technical showing that Straight Path places into the record of the proceeding that covers spectrum bands above 24 GHz for mobile radio services.

For the record, Straight Path currently has nine employees versus Boeing, which bills itself as the world's largest aerospace company with 159,469 employees as of February.

For more:
- see this Straigth Path filing

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