Feasibility of intelligent reflecting surfaces to combine terrestrial and non-terrestrial networks

Third-generation partnership project (3GPP) in Release 17 is working on the standardization of non-terrestrial networks (NTN) to enable 5G-based terrestrial networks to support NTN. Based on an initial version of Release 17, the NTN will consist of low earth orbit (LEO) satellites constellation, whereas the unmanned aerial vehicles (UAVs) and high-altitude platforms (HAPs) are considered as a special use case of NTN networks. Similar to the global positioning system (GPS), the NTN-based signals are unable to provide indoor coverage, as the signals from these satellites are attenuated and scattered by roofs, walls, etc. Moreover, the power and delay are the critical factors that restrict a cellular-enabled mobile handset to obtain reliability, seamless coverage, and low latency, while relying on NTN networks. Recent literature has proven that intelligent reflecting surfaces (IRSs) are much effective in tunning wireless signals to improve spectral and energy efficiencies, achieving seamless coverage, and faster data rates. The key feature of an IRS is to enhance the coverage of a wireless network by providing an additional channel gain only by reflecting the signals. In this chapter, we have carried out an analysis, based on recent literature, to study the feasibility of using IRSs in enabling the co-existence of NTN in terrestrial networks environment.