Energy-Efficient RIS-assisted Satellites for IoT Networks

The use of satellites to provide ubiquitous coverage and connectivity for the densely deployed Internet of Things (IoT) networks are expected to be a reality in the emerging 6G networks. Yet, the low battery capacity is of IoT nodes constitute a problem for the direct connectivity to satellites that are located up to 2000 km altitude. As an architectural novelty, in this paper, we propose the use of reconfigurable intelligent surface (RIS) units to help with the path loss associated with high transmission distances. The use of RIS units through broadcasting and beamforming approaches are shown to provide a significant gain in terms of their signal transmission. These units can be placed on the reflectarrays that are already available on the satellites. It is shown that RIS-assisted satellites can provide up to 10^5 times higher downlink and uplink achievable rates for IoT networks.