Report Summarizes Tests Showing LTE at 900 MHz Would Interfere with LMR
Friday, April 10, 2020 | Comments

NextEra Energy submitted to the FCC a report that the utility said provides evidence to rebut the claim by Anterix that no interference will be caused by Long Term Evolution (LTE) operations to adjacent narrowband LMR operations if a broadband segment is inserted into the 896 – 901/935 – 940 MHz band.

The report summarizes tests that were conducted to measure the compatibility of existing 900 MHz narrowband LMR receivers with broadband LTE operations on adjacent spectrum as proposed in the FCC’s WT Docket No. 17-200. LTE signals of various power levels were used to measure the LMR system response.

The data shows that the LMR receiver is not able to receive the intended LMR signals at low received power levels when compared to the LMR receiver operation without LTE operation. In other words, the tests indicate that LTE broadband signals (noise) interfere with LMR operations, the filing said.

The tests demonstrated that the LTE signal causes the sensitivity level — the received power level of the lowest LMR signal that can be successfully received and used by the LMR receiver — to degrade. Specifically, without the presence of an LTE signal the LMR device had a sensitivity of -121 dBm. This sensitivity degrades as an LTE signal is introduced and as the LTE signal power experienced increases, that is, sensitivity moves from -121 dBm to levels that are below -100 dBm.

“Because the LMR receiver is not able to receive signals that are below the -121 dBm sensitivity level, LTE signals can interfere with existing narrowband LMR operations in areas that today have good reception but where the intended LMR signal level is low,” the filing said.

The full filing from NextEra is here.

NextEra said the Utilities Technology Council (UTC) made the report available to its members. The report is here.

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On 4/10/20, David Stratton said:
Great articles. Thank you for keeping our group up to date.

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