Aggregate LTE Emissions

Aggregate LTE:  Characterizing User Equipment Emissions

On September 30, 2019, NASCTN published the project factor screening report "Characterizing LTE User Equipment Emissions: Factor Screening".  The data used for the report is also available here.

This report presents (i) a laboratory test methodology for measuring LTE UE emissions under a wide range of conditions, and (ii) the results of a factor screening experiment involving 28 factors (e.g., evolved node B (eNB) power control variables, eNB scheduling algorithms, network loading, traffic type) that aimed to determine which factors have a significant impact on physical uplink shared channel (PUSCH) power per physical resource block (PRB). The results demonstrate the validity of the proposed test methodology and illustrate how factor screening experiments can be used to better understand the emissions of typical commercial off-the-shelf LTE UEs.  In support of this study, a separate independent effort to capture and document UE antenna 3D pattern measurements is included as an appendix to the report and published as NIST Technical Note 2056. Another contribution to this study is a MITRE Corporation report titled "Investigations and Analyses of LTE Network Cell Tower Deployments and Impact on Path Loss Calculations", which informs the project with an understanding of real-world LTE network path loss and propagation characteristics.

This NASCTN project was initiated as a result of the 2014 AWS-3 spectrum auction, which assigned 1755-1780 MHz frequencies to commercial wireless carriers with conditions for sharing the spectrum with existing federal systems.  As carriers consider early network buildouts in this band, the Defense Information Systems Agency (DISA) Defense Spectrum Organization (DSO) is engaged in a broader effort to assess interference risk between the two types of systems, with aggregate LTE user equipment emissions as one potentially influential factor.

The draft test plan describes the methodology for measuring aggregate interference based on several factors, including the collective power distributions emitted by the UEs in a cell, the number of UEs transmitting simultaneously, the spectral properties of the UEs, channel characteristics on the path between the UEs and unintended receivers, and other special conditions relevant to the test environment. Phase 1 of the test plan will be set in a controlled lab environment to produce baseline reference variables for network configuration and accurate assessment of impact dependencies. 

Results of the NASCTN project may affect the business strategy and network design of commercial deployments during the time federal systems continue to operate in the 1755-1780 MHz band.

For additional reference, the documents may also be found at the following links: 

• Updated Draft Test Plan
• Adjudicated Comment Matrix 
• Presentation from Public Briefing

For more information, please contact us at nasctn [at] nist.gov (nasctn[at]nist[dot]gov).