The ASCENT project studies spectrum sharing between satellite and cellular networks using a licensed shared access (LSA) approach, in which information stored in a database is exploited to enable spectrum sharing between users. The project focuses on one side 5G pioneer bands 3.4-3.8 GHz and 24.25-27.5 GHz, which are well-recognized as satellite frequency bands, and on the other side on legacy international mobile telecommunication (IMT) frequency bands. We identified different spectrum sharing scenarios and defined four use cases. We have developed an LSA system testbed, which is used to study and validate the interest of the LSA approach in satellite/ terrestrial sharing scenarios. The results of our simulations and the tests realized on the testbed show that the LSA approach could be used to improve spectrum sharing between satellite and terrestrial networks. This approach could be envisaged to facilitate spectrum sharing between terrestrial mobile network such as international mobile telecommunications and satellite networks operating in a same frequency band. Such an approach could offer new spectrum sharing opportunities which could benefit to both mobile and satellite community. The LSA testbed and the results of the project will be further utilized to develop and assess new sharing scenarios that could lead to creating new spectrum opportunities for different radiocommunication systems.