Analysis of methods for EMF in-situ measurements of LTE base stations
Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
The purpose of this thesis is to analyze two proposed methods for in-situ measurements of electromagnetic fields transmitted by LTE base stations. One of the methods is based on measurements of physical broadcast channel (PBCH) using basic spectrum analyzer, whereas the other method is based on measurements of the reference signal (RS) using a decoder. Both alternatives are proposed to be used for extrapolation to the maximum electromagnetic field exposure level at full base station traffic load. The analysis is conducted with respect to instrument requirements, accuracy and time requirements. Different instrument settings of the spectrum analyzer and their impact on the measurement results is analyzed and discussed.
In this work around 70% cases from all the measurements; the spectrum analyzer method overestimate the electric field strength compared with the LTE decoder method. All spectrum analyzer based measurements conducted in the main beam of an antenna at distances of less than 100 m were within ± 20% compared with the decoder results. Measurement results obtained in a reflective environment show that both methods are affected by fading, but significant deviations between the two methods indicate that the spectrum analyzer method is more sensitive to frequency selective fading.
Based on the results and experiences obtained in this work the following conclusions have been drawn:
- In the main beam of an antenna and for distances from the antenna of less than 100 m the two methods agree within ± 20 %.
- When conducting spectrum analyzer based measurements in reflective environments it is important to follow standardized guidelines in order to avoid underestimating results
- The decoder based method is most suitable when assessing the electric fields within a specific cell, for example to determine the compliance boundary of an antenna, whereas the spectrum analyzer based method is more suitable for general assessment, e.g. measurements in environments such as offices or other areas where no specific antenna is considered and slight deviation is acceptable.
- The max-hold time for the spectrum analyzer method currently recommended in the latest draft of EN 50492 can be reduced to 5 s.
Place, publisher, year, edition, pages
2012. , 50 + 7 Appendicies p.
Other Engineering and Technologies not elsewhere specified
IdentifiersURN: urn:nbn:se:liu:diva-105538ISRN: LiU-ITN-TEK-A--12/042--SEOAI: oai:DiVA.org:liu-105538DiVA: diva2:708195
Subject / course