Measured Emission Spectra of Selected AWS-3 LTE Transmitters
Michael R. Frey, Geoffrey Sanders, Jolene Splett, John M. Ladbury, Frank Sanders, Azizollah Kord, Ryan T. Jacobs
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). It is possible that out-of-band (OoB) and spurious emissions from AWS-3 base stations (within LTE these are referred to as evolved node Bs, or eNBs) and their associated mobile units (called user equipment or UEs) might cause interference to these adjacent-band telemetry receivers. Electromagnetic compatibility (EMC) analyses for such interference will rely on knowing the power spectra of the OoB and spurious emissions of AWS-3 eNBs and UEs on frequencies used by telemetry link receivers. To determine these power spectra, the authors have measured transmitter OoB and spurious emissions of an AWS-3 eNB and selected UEs. Adaptive power attenuation allowed these measurements to be made 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. The results of those measurements are provided in this report. In general, AWS-3 eNB and UE transmitted emission spectra are found to be insensitive to variations in transmitter modulations, and resource block 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 were suppressed by at least 100 dB in the adjacent telemetry bands for the devices tested. The results can now be factored into EMC analyses for AWS-3 transmitters operating in proximity to telemetry receivers.
Band sharing, band sharing analysis, interference analysis, eNodeB (eNB), emission spectrum, telemetry links, user equipment (UE), AWS-3, 1755-1780 MHz, 2155 2180 MHz, Band 66, aeronautical mobile telemetry (AMT), out of band (OoB) emissions, spectrum measurements, spectrum sharing