## 1 Introduction
In recent years, the combination of non-orthogonal multiple access (NOMA) and HetNets has received a considerable amount of attention. Power-domain NOMA [13] allocates different power to different users according to their channel quality and transmits at the same time-frequency-code resources. In order to distinguish different users, successive interference cancellation (SIC) technology is used at the receivers. Consequently, compared with OMA, NOMA can significantly enhance spectral efficiency at the cost of increased receiver complexity. In [14], the author evaluated the combination of NOMA and HetNets by capacity gain and the impact of different user pairing methods was taken into consideration. That demonstrates the potential of NOMA HetNets in the context of the high data demand of networks. Moreover, the performance of NOMA and OMA in HetNets is investigated in terms of the coverage probability, achievable rate and energy efficiency in [15; 16]. The problem of power allocation of MBS and PBS [17] and the problem of user pairing (UP) and power allocation (PA) [18] were proposed to improve the throughput of each user. In addition, energy efficiency [19; 20; 21] and fairness [22; 23] are also a hotspot for NOMA HetNets. Compared with non-NOMA HetNets, co-tier interference, cross-tier interference and NOMA co-channel interference make the interference coordination more complex in NOMA HetNets. Interference management based on compressive sensing (CS) [24] and interference management based on interference alignment and coordinated beamforming (IA-CB) [25] were proposed. In [26], A user scheduling scheme and distributed power control algorithm were proposed to improve the spectral efficiency and outage performance. Moreover, the interference coordination strategy of the frequency-domain [27; 28] and the strategy of the space-domain [29; 30] have been considered. Most of the abovementioned research focuses on interference coordination of NOMA HetNets; however, there is a lack of interference coordination optimization strategy for the time-domain of NOMA HetNets. Therefore, inspired by current research, this paper takes two-tier HetNets with an uneven distribution of users into consideration where CRE and ABS are applied to interference coordination. A novel user pairing scheme is proposed and the condition that the throughput of the user does not drop as the transmission subframe switch is derived. Moreover, we derive the expression of the dynamic power allocation factor according to the condition of the smallest difference between the users of the same pair. Moreover, the proposed user pairing scheme can perform dynamically based on the ABS ratio and has better performance than other user pairing schemes of similar complexity. Finally, we take the idea of game theory to reduce the computational complexity of the joint optimization algorithm of adaptive CRE and ABS. Moreover, the proposed interference coordination optimization strategy can effectively manage interference and the network with the proposed strategy and has better performance than a network with other strategies. The remainder of the paper is structured as follows: In Section 2, the system model is constructed. Section 3 presents the entire interference coordination optimization strategy. Simulation and numerical results are given and analyzed in Section 4, and the conclusion is summarized in Section 5.