As of now all sub-8 GHz 5G NR deployments are based on Time Division Duplex (TDD) and therefore use unpaired frequency bands at the 3.5 GHz frequency range. Phase 2 of 5G NR network deployments, anticipated for mid-2020, will utilize Frequency Division Duplex (FDD) mode. Almost 90% of all spectrum is organized as paired frequency bands, where downlink and uplink transmission are separated by frequency. However, all the targeted frequency bands are already in use by 4G LTE. To enable the use of the spectrum and enable a smooth transition from LTE to 5G without the need for spectrum refarming, spectrum sharing principles have been embedded into the 5G NR standard. In this presentation we will introduce the spectrum sharing principle called dynamic spectrum sharing (DSS) and analyze related test and measurement challenges from a network and device testing point of view.