AT&T said SpaceX’s requested “ninefold increase” to the allowable power flux-density limits for out-of-band emissions “would cause unacceptable harmful interference to incumbent terrestrial mobile operations. Specifically, AT&T’s technical analysis shows that SpaceX’s proposal would cause an 18% average reduction in network downlink throughput in an operational and representative AT&T PCS C Block market deployment.”
Assuming a handset antenna gain of -3 dBi, SpaceX’s proposal still results in an interference to noise (I/N) ratio of -3 dB—well above the ITU [International Telecommunication Union] threshold SpaceX claims would protect terrestrial devices. SpaceX’s proposed margin therefore fails to adequately protect terrestrial user equipment from potential interference from SCS satellite systems, including user equipment that may not fall within the flagship performance parameters, and should be rejected.”