Ligado LTE Plans Raise Red Flags for AWS-3, SNR Wireless Says

said Ligado's plans to relinquish its rights to use 1545-1555 MHz and to seek access to the 1675-1680 MHz band (see 1512310016) carry multiple interference issues for AWS-3 licensees like it. The designated entity which has been affiliated with Dish Network said interference issues include that the total amount of energy received at earth stations receiving signals from geostationary operational environmental satellites and polar-orbiting operational environmental satellites in the 1675-1710 MHz band will increase, and the Ligado-commissioned interference analysis doesn't look at the effect of licensed commercial AWS-3 uplink operations in 1695-1710 MHz. And the AWS-3 interference analysis done by the Commerce Spectrum Management Advisory Committee (CSMAC) didn't look at commercial downlink operations in 1675-1680 MHz, SNR said. The proximity of 1675-1680 MHz commercial downlink operations to 1695-1710 MHz commercial uplink operations heightens the likelihood of AWS-3 base station receiver overload or of out-of-band emissions causing base station interference, SNR said, adding that the FCC and AWS-3 auction bidders didn't contemplate those interference scenarios before the auction. The CSMAC process set up recommended protection distances around meteorological earth stations that commercial AWS-3 operators in the 1695-1710 band had to coordinate within, and Ligado's proposal -- by adding to the interference at federal users' earth stations -- would eat up some of the interference budget AWS-3 licensees have now, SNR said. "Ligado's proposal is therefore flawed because it will be impossible to allocate any interference budget amount to its proposed use without also 'stealing' interference budget from AWS-3 spectrum acquired at auction on the basis of an interference budget allocation that was codified in the FCC's rules." SNR said Ligado's LTE plan makes it tough to reconcile interference federal users see between AWS-3 operations and 1675-1680 MHz base station operations. In a statement Wednesday, Ligado said, "The communications industry routinely addresses spectrum coordination and co-existence issues, resolving them through the FCC process, standards bodies, and discussions between the various stakeholders. The issues raised occur frequently in spectrum discussions -- recent examples include bands affected by AWS-4. We look forward to a public comment process to discuss these types of issues with all affected stakeholders."