An Overview of Performance Analysis and Optimization in Coexisting Satellites and Future Terrestrial Networks

The existing radio frequency band is overcrowded and will soon be unable to accommodate the growing demand for greater data rate services. Consequently, considerable efforts are being undertaken to develop adaptable spectrum-sharing techniques and handle the unprecedented data traffic demands. Using satellite services to enhance terrestrial communications is emerging as a cutting-edge solution for future application-aware networks. The coexistence of space and ground communications infrastructures, however, introduces exacerbated levels of wireless interference. Hence, intelligent resource allocation strategies are essential to ensure dependable communication and high-capacity broadband access globally. To this end, this manuscript surveys the advances in optimization and performance analysis methods in coexisting satellites networks and future wireless systems. The paper first presents an overview of the existing papers related to the more general scope of space-air-ground communications. The survey then highlights optimization frameworks for coexisting satellites and sixth-generation communication systems (6G), focusing on maximizing sum rate, maximizing energy efficiency,and minimizing transmit power. Additionally, the survey presents a number of papers dealing with performance analysis, namely outage probability, ergodic capacity, average symbol error rate, and effective capacity. The paper further discusses the critical challenges imposed by such integrated systems, e.g., backhaul-access cross-interference, resource coordination, channel modeling, and algorithmic complexity. Finally, we identify several open research issues, e.g., a cognitive radio approach to the considered network, integrated backhaul-access system, integration with emerging disruptive systems, artificial intelligence, and quantum communication technologies for coexisting satellites and future terrestrial networks.