Optimization Of Non-orthogonal Multiple Access Transmission For Satellite-Terrestrial Link Under Terrestrial Base Station Cooperation

As the next generation of wireless communication network,the advent of satelliteterrestrial integrated network(STIN)is expected to integrate satellite systems with terrestrial systems,in which the terrestrial relay network can provide complementary coverage for coverage blind spots in satellite networks,and seamless network coverage is enabled to provide global users with high-speed and large-capacity services.In addition,multi-user signals can be rapidly modulated and demodulated to the same time/frequency resource block using a high-performance power controller and SIC receiver with low complexity.Such that applying the NOMA transmission strategy to the satellite-terrestrial integrated relay system is a prominently promising solution for enabling large-scale connectivity and reliving the spectrum scarcity.However,new transmission strategy and energy-hungry devices necessitate a shift in network resource management.To tackle the above-mentioned issue,the investigation of the transmission strategy based on energy-efficient optimization is developed for NOMASTIN system in this thesis.The main contributions are summarized as follows:(1)To tackle the difficulties in resource management caused by heterogeneous networks and NOMA transmission,the system interference model is constructed,which includes the interference between heterogeneous systems and NOMA cochannel interference.Simulation results show that increasing transmission power will aggravate the interference between systems,whereas a reasonable power setting or an optimal SIC decoding strategy can effectively reduce the negative impact of interference on system capacity.(2)To tackle the energy scarcity of the NOMA-STIN system,this thesis investigates the transmission strategy to improve the system’s energy efficiency.In order to meet the heterogeneity and time-varying characteristics of the satellite links and terrestrial links,an optimization problem was constructed with maximal system ergodic energy efficiency as the objective function,a minimal Qo S limit,and peak/average power limits at both satellite and terrestrial base stations as the constraints.The stochastic fraction programming algorithm based on the Dinkelbach method and the stochastic SCA algorithm are used to solve it.Such that a stochastic convex proxy problem with a differential objective function for the original problem is constructed.And the optimal power expression is derived based on the Lagrangian decomposition method.Finally,an optimal power allocation algorithm with polynomial complexity is designed.The convergence and optimality of the proposed algorithm are verified by simulation.And the effectiveness of the proposed transmission strategy is evaluated.(3)To improve the energy consumption fairness among users in the NOMA-STIN system,this thesis investigates the transmission strategy to improve the users’ energy efficiency.An optimization problem is formulated with max-min ergodic energy efficiency as the objective function,minimal Qo S requirements,carrier scheduling,maximal user transmit power limits,backhaul capacity limits,and SIC optimal decoding as the constraints.From the perspective of policy decomposition,the optimal carrier scheduling strategy and algorithm are proposed using quadratic programming optimization theory.The power control theory under dynamic decoding-order is developed based on the power allocation theory in(2),and the optimal joint power control-SIC decoding optimization(JPD)strategy and optimal algorithm are proposed.Finally,a transmission strategy based on joint carrier sche duling-power control-SIC decoding optimization(JSPD)is proposed,and a suboptimal algorithm with polynomial complexity is designed.The convergence and suboptimality of the proposed algorithm are verified by simulation.Results show that the proposed transmission strategy is effective in improving the Jain fairness of users’ ergodic energy efficiency.