mmWave is a sub-type of 5G associated with the potential for ultra-high speeds. However, it is also lumbered with a perception of being unreliable due to weak reception. Qualcomm, Ericsson and Casa Systems seek to change that with its latest claim of a data call using these bands conducted over a distance of nearly 4 kilometers (km).
https://www.notebookcheck.net/Qualcomm-and-its-5G-broadband-partners-claim-to-have-completed-the-world-s-longest-range-mmWave-data-call.490921.0.html