Allowing proposed terrestrial wireless video companies like Northpoint Technology to share spectrum with existing and planned satellite TV services "poses a significant interference threat to direct broadcast satellite operation," unless suitable "mitigating measures" are taken. And even with such measures, there is risk of residual interference. That was the conclusion of independent engineering firm Mitre Corp. last week in a study for Congress.
Congress called for the report as a result of the fight between Northpoint and the satellite industry over whether Northpoint can offer terrestrial video and data services using the 12.2-12.7 GHz spectrum band allocated to DBS.
The satellite industry argues that Northpoint's system would cause too much interference and interrupt DBS customers' service. Northpoint says any interference would be neglible and that the satellite industry is only trying to exclude competitors from the market.
Both sides claimed victory after the FCC released the report last week.
"Mitre correctly concluded that satellite-terrestrial sharing requires specialized technology like Northpoint in order to be effective and that, without a system such as Northpoint, sharing cannot work," said Sophia Collier, president of Broadwave USA, Northpoint's parent company.
The satellite industry, however, saw the report as vindication. "The satellite TV providers and the SBCA have claimed from the outset that Northpoint's proposed terrestrial service would cause harmful interference to DBS signals, and the independent tests conducted by Mitre have unequivocally validated our conclusion," said Chuck Hewitt, president of the Satellite Broadcasting and Communications Association.
While the report found that any MVDDS operating in the DBS band would cause interference, it also said "mitigation techniques" could enable spectrum sharing by Northpoint and DBS companies DirecTV and EchoStar Communications, as well as other satellite systems offering high-speed data services.
"Multichannel Video and Data Distribution Services (MVDDS) and DBS band sharing appear feasible if and only if suitable mitigation measures are applied," wrote Mitre. "Different combinations of measures are likely to prove 'best' for different locales and situations."
Mitre left it to the FCC to decide whether "the potential costs of applying the necessary mitigatory measures ... outweigh the benefits that would accrue from allowing [the two] to coexist." The FCC has opened the question to the public, with comments due May 15 and replies May 23.
The mitigating measures Mitre recommends could be complicated and costly. Among the techniques listed are moving DBS customers' satellite dishes from the source of interference, shielding the dishes and strategically locating transmitters.
The report said that these techniques could be used to keep potential interference down to about two hours per year but suggested that all mitigation systems be in place before the FCC hands out the first license.