Tests Find H-Block Interference Threatens PCS Phones
Sprint and Nokia said new test results show use of the H-band for mobile services could lead to massive interference problems for other PCS users. Sprint filed the results at the FCC on the eve of a decision whether to place the H-band auction item on the Sept. 9 meeting agenda. Late Thurs. the item was on the sunshine notice for the meeting, cutting off further debate and dealing Sprint and other carriers a blow.
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The Sprint-Nokia filing was significant in providing the first tests that show interference, sources said. A source said the lab was one of the few in the U.S. that could mimic H-block interference. “We did measured testing,” the source said. “We were surprised that the interference was so bad.”
“Why is [the Commission] in such a big hurry?” a carrier source asked. “We hope this is enough to get them to think a little bit more. At least the service rules need to account for this” interference. Sources have predicted for the past week, based on many meetings at the FCC, that the Commission would move forward on the H-block order despite objections from most wireless carriers. Nextel has supported moving forward on the item.
“We have consistently been telling the Commission this is an issue they need to take seriously,” said a 2nd carrier source. “We're concerned that the Nokia tests are just the tip of the iceberg.”
Nokia said it conducted the tests the last week of Aug. The handset-maker tested 7 phones by 3 manufacturers. One source said the problem is that the H- block was designed as a buffer -- a gap between transmissions; current wireless phones and those in development, haven’t been designed with filters that can handle high-power “noise” in that part of the radio spectrum.
“Test results show harmful interference will occur to millions of existing PCS handsets in the presence of an H- block signal,” Nokia said. “One active H Block device could prevent another nearby handset from placing and receiving a call.” At the very least, the results make clear, the companies said, that the FCC would have to order significant power limitations “likely throughout the H Block transmit band” to protect PCS incumbents.
Among the results, Nokia said it subjected one common handset, which it labeled “phone 3,” to interference from an H-block set operated at only 166 mW -- less than 10% of the power permitted for mobile phones. Nokia found this would cause an “unacceptable” 90% frame error rate that would effectively make the phone unusable. “Millions of existing customers receive PCS services using these handsets today,” Nokia said. “To put this into perspective, for example, more than 2 million Sprint subscribers are using test phone 3 today.” - Howard Buskirk