On the Performance of Cache-Free/Cache-Aided STBC-NOMA in Cognitive Hybrid Satellite-Terrestrial Networks

Future wireless networks pose several challenges such as high spectral efficiency, wide coverage, massive connectivity, low receiver complexity, etc. To this end, letter investigates an overlay-based cognitive hybrid satellite-terrestrial network (CHSTN) combining non-orthogonal multiple access (NOMA) and conventional Alamouti space-time block coding (STBC) techniques. Herein, a decode-and-forward based secondary terrestrial cooperates with primary satellite for dynamic spectrum access. Further, reliable content delivery latency requirements, caching is employed, whereby the can store most popular contents of network. Considering relevant heterogeneous fading channel models NOMA-based imperfect successive interference cancellation, we examine performance CHSTN cache-free (CF) STBC-NOMA cache-aided (CA) schemes. We assess outage probability expressions further, highlight corresponding achievable diversity orders. Indicatively, proposed CF/CA schemes perform significantly better than benchmark standalone NOMA OMA