Abstract
In this paper, a hybrid satellite-terrestrial spectrum sharing system allows terrestrial secondary network to cooperate with a primary satellite network and to further provide higher spectrum efficiency. For massive connections design, we implement non-orthogonal multiple access (NOMA) technique to form cognitive radio based satellite-terrestrial (CR-NSHT) system relying on NOMA and further achieve more benefits compared with traditional schemes. The secondary network only remains its stable operation when the outage probability of such system is guaranteed, and thereby, to explore advantages of spectrum sharing opportunities. Considering Shadowed-Rician fading for satellite links, and Nakagami- $m$ as well as Rician fading for terrestrial links, we derive the closed-form expressions of the outage probability to evaluate the performance of secondary network. We consider further system performance metrics including ergodic capacity, energy efficiency and multi-user scenarios. We also demonstrate the impacts of power allocation factors, transmit signal-to-noise ratio (SNR) at the source, parameters of satellite links, target rates, and fading severity parameters on the system performance. Numerical and simulation results validate our analysis and highlight the performance gains of the proposed schemes for CR-NSHT with relay link serving secondary network and direct link serving the primary network.
Highlights
To resolve the challenge of line-of-sight satellite communication systems blocked by heavy shadowing or obstacles [1], the authors in [2]–[6] has been studied a hybrid satellite-terrestrial system
In this study, we have investigated the system performance of the cognitive radio (CR)-NOMA-aided hybrid satellite-terrestrial systems (NHST) system relying on non-orthogonal multiple access (NOMA) in terms of outage probability, ergodic capacity, energy efficiency and throughput
We have derived the closed-form expressions of outage probability, defined expression of ergodic capacity to show how different performance of the two users in the secondary network over some sets of channels. These derived expressions were validated by numerical results, and the outage events of two users were compared with OMA case
Summary
To resolve the challenge of line-of-sight satellite communication systems blocked by heavy shadowing or obstacles [1], the authors in [2]–[6] has been studied a hybrid satellite-terrestrial system. Outage probability of the hybrid satellite-terrestrial network was analyzed to indicate the secrecy performance by introducing the closed-form formula for the single-relay selection and baseline round-robin scheduling modes [12]. The authors in [26] introduced how NOMA benefits to hybrid satellite-terrestrial relay network Such NSHT enhances ability of spectrum sharing in the manner of the underlay architecture. The authors in [31] considered the underlay CR-HSTN including a primary satellite source with its terrestrial receiver and the secondary transmitter (ST) with its pre-paired users on the ground They derived a novel closed-form formula to exhibit the outage performance of secondary network in the existence of primary interference power constraint imposed by the adjacent primary satellite network.
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