标题：On Downlink NOMA in Heterogeneous Networks with Non-Uniform Small Cell Department
作者：Han, Tao; Gong, Jie; Liu, Xiong; Islam, S. M. Riazul; Li, Qiang; Bai, Zhiquan; Kwak, Kyung Sup
作者机构：[Han, Tao; Gong, Jie; Liu, Xiong; Li, Qiang] Huazhong Univ Sci & Technol, Sch Elect Informat & Commun, Wuhan 430074, Hubei, Peoples R China.; [Islam 更多
通讯作者地址：[Li, Q]Huazhong Univ Sci & Technol, Sch Elect Informat & Commun, Wuhan 430074, Hubei, Peoples R China.
关键词：Non-orthogonal multiple access; heterogeneous network; coverage; probability; achievable rate
摘要：Compared to orthogonal multiple access (OMA), non-orthogonal multiple access (NOMA) can achieve higher spectral efficiency by exploiting the power domain multiplexing. In this paper, we investigate the performance of NOMA in a two-tier heterogeneous network (HetNet) with non-uniform small cell deployment, where critical performance metrics like coverage probability and achievable rate are analyzed. First, a NOMA-based HetNet model is established, where users are paired based on the proposed user pairing scheme. Then the distribution of the order statistics for the distances between different NOMA users and the serving base station (BS) is presented considering the channel qualities from the NOMA users to the BSs. On this basis, we analytically demonstrate the impact of various network parameters on the coverage probability and achievable rate of NOMA users, such as signal-to-interference-plus-noise ratio threshold and BS density. Furthermore, an analysis is presented to provide insight into the energy efficiency of the considered system. Finally, extensive simulation and comparisons are conducted, which validate the advantages of NOMA over OMA in the considered HetNet environment.