With the rapid proliferation of smart devices in wireless networks, more powerful technologies are expected to fulfill the network requirements of high throughput, massive connectivity, and diversify quality of service. To this end, rate splitting multiple access (RSMA) is proposed as a promising solution to improve spectral efficiency and provide better fairness for the next-generation mobile networks. In this paper, the outage performance of uplink RSMA transmission with randomly deployed users is investigated, taking both user scheduling schemes and power allocation strategies into consideration. Specifically, the greedy user scheduling (GUS) and cumulative distribution function (CDF) based user scheduling (CUS) schemes are considered, which could maximize the rate performance and guarantee scheduling fairness, respectively. Meanwhile, we re-investigate cognitive power allocation (CPA) strategy, and propose a new rate fairness-oriented power allocation (FPA) strategy to enhance the scheduled users' rate fairness. By employing order statistics and stochastic geometry, an analytical expression of the outage probability for each scheduling scheme combining power allocation is derived to characterize the performance. To get more insights, the achieved diversity order of each scheme is also derived. Theoretical results demonstrate that both GUS and CUS schemes applying CPA or FPA strategy can achieve full diversity orders, and the application of CPA strategy in RSMA can effectively eliminate the secondary user's diversity order constraint from the primary user. Simulation results corroborate the accuracy of the analytical expressions, and show that the proposed FPA strategy can achieve excellent rate fairness performance in high signal-to-noise ratio region.

翻译：随着无线网络中智能设备的快速普及，需要更强大的技术来满足高通量、大规模连接和多样化服务质量等网络需求。为此，速率分裂多址接入（RSMA）被提出作为提升频谱效率并改善下一代移动网络公平性的有前景方案。本文研究了随机部署用户场景下上行链路RSMA传输的中断性能，综合考虑用户调度方案与功率分配策略。具体而言，考虑贪婪用户调度（GUS）和基于累积分布函数（CDF）的用户调度（CUS）两种方案，分别用于最大化速率性能和保障调度公平性。同时，我们重新研究了认知功率分配（CPA）策略，并提出一种面向速率公平性的新型公平功率分配（FPA）策略以增强被调度用户的速率公平性。通过采用顺序统计量和随机几何方法，推导了每种调度方案结合功率分配的中断概率解析表达式以表征性能。为获得更深层次的认知，还推导了各方案的分集增益阶数。理论结果表明，采用CPA或FPA策略的GUS和CUS方案均可实现全分集阶数，且RSMA中应用CPA策略可有效消除主用户对次用户分集阶数的约束。仿真结果验证了解析表达式的准确性，并表明所提FPA策略在高信噪比区域能实现优异的速率公平性能。