This paper investigates the application of a unified non-orthogonal multiple access framework in beam hopping (U-NOMA-BH) based satellite communication systems. More specifically, the proposed U-NOMA-BH framework can be applied to code-domain NOMA based BH (CD-NOMA-BH) and power-domain NOMA based BH (PD-NOMA-BH) systems. To satisfy dynamic-uneven traffic demands, we formulate the optimization problem to minimize the square of discrete difference by jointly optimizing power allocation, carrier assignment and beam scheduling. The non-convexity of the objective function and the constraint condition is solved through Dinkelbach's transform and variable relaxation. As a further development, the closed-from and asymptotic expressions of outage probability are derived for CD/PD-NOMA-BH systems. Based on approximated results, the diversity orders of a pair of users are obtained in detail. In addition, the system throughput of U-NOMA-BH is discussed in delay-limited transmission mode. Numerical results verify that: i) The gap between traffic requests of CD/PD-NOMA-BH systems appears to be more closely compared with orthogonal multiple access based BH (OMA-BH); ii) The CD-NOMA-BH system is capable of providing the enhanced traffic request and capacity provision; and iii) The outage behaviors of CD/PD-NOMA-BH are better than that of OMA-BH.

翻译：本文研究了基于波束跳跃的统一非正交多址框架（U-NOMA-BH）在卫星通信系统中的应用。具体而言，所提出的U-NOMA-BH框架可应用于基于码域非正交多址的波束跳跃（CD-NOMA-BH）系统以及基于功率域非正交多址的波束跳跃（PD-NOMA-BH）系统。为满足动态不均匀的业务需求，我们通过联合优化功率分配、载波分配和波束调度，建立了以最小化离散差平方为目标的最优化问题。利用Dinkelbach变换和变量松弛方法解决了目标函数与约束条件的非凸性。进一步地，推导出了CD/PD-NOMA-BH系统中中断概率的闭合表达式和渐近表达式。基于近似结果，详细获得了用户对的多样性阶数。此外，在延迟受限传输模式下讨论了U-NOMA-BH的系统吞吐量。数值结果验证了：i) CD/PD-NOMA-BH系统的业务请求差距相较于基于正交多址的波束跳跃（OMA-BH）系统更为接近；ii) CD-NOMA-BH系统能够提供增强的业务请求与容量供给；iii) CD/PD-NOMA-BH的中断性能优于OMA-BH系统。