On Performance Analysis of NOMA-Aided Hybrid Satellite Terrestrial Relay With Application in Small-Cell Network

Satellite communication systems need to be integrated with emerging small-cell network to provide seamless connectivity and high-speed broadband access for mobile users in future wireless networks. In this paper, we study a hybrid satellite-terrestrial relay system (HSTRS) employing small cell transmission under interference constraint with macro-cell users. To characterize such HSTRS-assisted small-cell network, Shadowed-Rician fading for satellite links and Nakagami-$m$ fading for terrestrial links are adopted. We further deploy non-orthogonal multiple access (NOMA) to improve spectrum efficiency. To provide performance analysis, we derive exact formulas for outage probability and throughput of the considered HSTRS, and further examine its achievable diversity order. More importantly, we conduct the performance analysis by indicating performance gaps among two users, and such a gap depends on power allocation factors. We evaluate key performance metrics through the derived analytical expressions to provide useful framework of HSTRN and to characterize the impact of interference in different cells, and integer values of the per-hop fading severity parameters. The useful guidelines are introduced in the design of futuristic HSTRS for small-cell communications.