Improving SINR via joint beam and power management for GEO and LEO spectrum-sharing satellite communication systems

In this paper, we investigate a geosynchronous earth orbit (GEO) and low earth orbit (LEO) coexisting satellite communication system. To decrease the interference imposed on the GEO user caused by LEO satellites, we propose a joint beam-management and power-allocation (JBMPA) scheme to maximize signal-to-interference plus noise ratio (SINR) at the GEO user, whilst maintaining the ongoing wireless links spanning from LEO satellites to their corresponding users. Specifically, we first analyze the overlapping coverage among GEO and LEO satellites, to obtain the LEO-satellite set in which their beams impose interference on the GEO user. Then, considering the traffic of LEO satellites in the obtained set, we design a beam-management method to turn off and switch interference beams of LEO satellites. Finally, we further propose a deep Q-network (DQN) aided power allocation algorithm to allocate the transmit power for the ongoing LEO satellites in the obtained set, whose beams are unable to be managed. Numerical results show that comparing with the traditional fixed beam with power allocation (FBPA) scheme, the proposed JBMPA can achieve a higher SINR and a lower outage probability, whilst guaranteeing the ongoing wireless transmissions of LEO satellites.