Measured Emission Spectra of Selected AWS-3 LTE Transmitters

Abstract

Version three of Advanced Wireless Services (AWS 3) radio systems will soon use spectrum that is adjacent to bands currently used by airborne telemetry links at U.S. government test and training ranges (TTRs). Spectrum sharing analyses need to be performed to determined how much off-tuning (number of megahertz) and distance separation (number of kilometers) are needed between AWS 3 transmitters and telemetry receiver stations to avoid harmful interference to those receivers. To complete these studies, detailed wide dynamic range emission spectrum measurements of representative models of the soon-to-be-deployed AWS 3 transmitters have been performed. This report describes those measurements, and the method used to obtain them. These measurements have been performed with over 100 decibels (dB) of dynamic range. The measurements have been collected in a variety of resolution bandwidths, transmitter modulations, and types of transmitter loading (i.e., number of resource blocks used) for two measurement detector modes. In general, AWS 3 eNB and UE transmitted emission spectra are found to be insensitive to variations in transmitter configurations. The measured power spectra of the eNBs and UEs vary in direct proportion to measurement (or receiver) bandwidth (i.e., as 10 log measurement bandwidth) with an approximate offset of about 10 dB between peak and average levels. The measurement results indicate that AWS 3 eNB and UE power spectra are suppressed by at least 100 dB in the adjacent telemetry bands for the devices tested. These results can now be factored into EMC analyses for AWS 3 transmitters operating in proximity to telemetry receivers. The work described in this report was performed by the National Advanced Spectrum and Communications Test Network (NASCTN). Results were published simultaneously as NASCTN Report 4, NTIA Technical Report TR-18-528, and NIST Technical Note TN 1980.