为了改善异构网络上行链路的性能及提高网络覆盖概率，提出了采用解耦上下行链路级联和双连接方案的NOMA异构网络模型，设计了一种条件解耦上下行链路级联分析框架。同时，考虑了3种可能的上行链路级联场景，在给定的下行链路级联条件下对解耦上行链路级联进行设计和分析，推导了解耦上行链路级联概率表达式，获得了主、次接入距离统计描述。数值和仿真分析首先研究了系统参数对级联概率的影响，分别研究了解耦上下行链路级联和耦合上下行链路级联方案下NOMA异构网络的条件覆盖概率和频谱效率。实验结果表明，在NOMA双连接异构网络中，所提出的DUDA方案的覆盖概率性能优于传统的CUDA方案的。此外，2种方案的频谱效率性能好坏与系统参数相关。

In order to improve the uplink performance of heterogeneous networks and coverage probability, this paper proposes a non-orthogonal multiple access (NOMA) heterogeneous network model by integrating decoupled uplink/downlink association (DUDA) and dual-connectivity schemes, and an analysis framework of conditional decoupled uplink and downlink association is designed. Meanwhile, three possible uplink association scenarios are considered, the design and analysis of the decoupled uplink associations are performed under the given conditional downlink association, and the probability expressions of the coupled uplink associations are derived. We get the statistical description of the primary and secondary access distances. Firstly, the numerical and simulation analysis shows the effect of system parameters on the association probability. Secondly, we study the conditional coverage probability and spectrum efficiency of the NOMA heterogeneous network under coupled uplink and downlink association and coupled uplink and downlink association schemes, respectively. The experimental results show that, the coverage probability performance of the proposed DUDA scheme is better than the traditional coupled uplink and downlink association (CUDA) scheme. In addition, the spectrum efficiency performance of the two schemes is related to system parameters.