The main objective of this project is to design, develop, test and verify a software testbed for multi-satellite diversity of Low Earth Orbit (LEO) constellations both in high and low-frequency scenarios to combat the detrimental effects of shadowing, multipath fading, channel blockage events, and Doppler shifts. The proposed diversity techniques either switched-based or combined diversity, and system scenarios will be implemented in a software testbed aiming at an average of 50% improvement in achievable peak rate at user terminals with at least two visible satellites, and reduction of outage probability by a factor of 2 when two or more satellites are visible. Low-gain single beam terminals with omni-directional antennas will be evaluated for low frequency scenarios (S-band), whereas multi-beam user terminal employing well-known multiple input multiple output techniques (MIMO) will be assessed in high-frequency scenarios (Ka-Band, Ku-Band) in high-gain multi-beam ground terminals. Moreover, the proposed diversity techniques will be adapted to the 5G NR Non-Terrestrial Networks (NTN) standard as proposed by 3GPP to increase the QoS of user terminals i.e., enhanced peak data rate and low probability of outage.