This project developed test processes and performed out-of-band emissions measurements of LTE systems that will be operating in the AWS-3 band so that DOD can mitigate potential interference effects on their aeronautical mobile telemetry (AMT) systems that are used at DOD test ranges.
In January 2018, NASCTN held a final public briefingfor its release of the completed “Measured Emission Spectra of Selected AWS-3 LTE Transmitters."
The project, proposed by Edwards Air Force Base, measured Out-of-Band (OoB) emissions from new Long Term Evolution (LTE) systems operating in bands adjacent to existing incumbent Department of Defense (DoD) Aeronautical Mobile Telemetry (AMT) systems used at government test and training ranges (TTRs). The test measured the OoB emissions of LTE evolve Node B (eNB) and User Equipment (UEs) operating in the Advanced Wireless Service (AWS)-3 frequencies adjacent to the L and S frequency bands currently used AMT systems. This data can be used by government organizations to determine the level of OoB emissions they can expect from LTE systems and plan any mitigation strategies.
The report details power spectral densities of AWS-3 LTE OoB emissions with high dynamic range (~100 dB) with the potential to impact operation of physically co-located AMT systems in adjacent bands. The test design evaluated a variety of LTE transmitter modulations, resolution bandwidths, loading parameters, and handset models. The results reveal that AWS-3 LTE eNB and UE transmitted emission spectra are insensitive to variations in transmitter modulations and resource block configuration, and their power spectral densities were suppressed by at least 90-100 dB in the adjacent telemetry bands for the devices tested. In addition, the test report details test calibration procedures, frequency scan sequencing, and tuning configurations that may be recommended for consideration in future experiments of transmitter OoB emissions.