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PIM measurements on a multiband antenna in the project “5G-Reallabor”

08.12.2020

Passive intermodulation (PIM) leads to interference signals in cellular networks and can therefore degrade network quality. In the project “5G-Reallabor”, PTB is working on traceability for PIM measurements in a laboratory environment with the aim of characterizing and reducing the measurement uncertainties and, thus, of contributing to the reliable function of the cellular network.

  

The new 5G mobile communications standard is currently being expanded and put into operation in Germany. The new standard enables higher data rates, lower latencies and higher reliability. To support this development, the aim of the project “5G-Reallabor” is to explore and to vividly present some practical use-cases of 5G as a key technology in the context of a smart region / smart city. To this end, an open real-world laboratory and showcase for stakeholders from business, science, administration and politics, as well as citizens and society, will be set up and integrated with regional platforms and test fields. A transfer of results into economic value chains should be guaranteed. The project is based on implementation, demonstration and evaluation of the practice-oriented use cases in the public 5G networks from established mobile network operators with the participation of industry, research institutions and the municipalities of Braunschweig and Wolfsburg. The expansion of the 5G infrastructure in the region is being carried out by prioritizing the network expansion plans of the mobile network operators. The funding volume for the research project amounts to almost 12 million euros for 12 sub-projects in the application fields of mobility (road, rail, air), eHealth and Smart Construction, as well as for technology-oriented cross-sectional activities.

PTB’s working group 2.24 “Non-Linear High-Frequency Metrology for Digitalization” is leading a sub-project from the area of technology-oriented cross-sectional activities, which deals with PIM as an interfering signal in mobile communications and especially in the new 5G network. PIM is a non-linear disturbance signal which can be caused by a variety of factors such as corroded connectors, contamination or external sources as, e.g., a rusty roof in the area. Locating and mitigating such sources of interference is essential for the mobile network to function reliably (Figure). The aim is therefore to minimize PIM sources at the base stations and, thus, to guarantee an optimal network supply, which fully utilizes the capacity of the systems. For this purpose, a traceability chain of the PIM measurement is being developed, which on the one hand enables a reduction in the uncertainty and on the other hand allows for the measurements and methods to be compared. The field devices calibrated according to this method deliver accurate and comparable results which can be used to minimize PIM.

Dynamic PIM measurement being carried out on a multiband antenna

Figure: Dynamic PIM measurement being carried out on a multiband antenna. Tapping lightly on the connector during the measurement generates mechanical stress. A mobile PIM analyzer is used to detect the interference signal and to localize the source.

 

 

 

 

Department 2.2 “High Frequency and Electromagnetic Fields