In this paper, we study the downlink resource allocation and cross-tier interference management in a heterogeneous cellular network. To cross-tier interference control, we proposed an orthogonal frequency division multiple access (OFDMA)-non-orthogonal multiple access (NOMA)-based scheme which macro base station (MBS) only uses OFDMA-based sub-channels (OBSCs) and the total bandwidth (OBSCs and NOMA-based sub-channels (NBSCs)) is available for small BSs (SBSs). The resource allocation problem is formulated as a non-convex NP-hard optimization problem which jointly designs the sub-channel assignment and power allocation for maximizing the sum-rate performance. To reduce the computational complexity, we solve this problem with three steps. First, for sub-channel assignment, we solve a convex problem by using available on-line optimization solvers. Second, we approximate the non-convex power allocation problem into a convex optimization problem and obtain the power allocation policy through the Lagrange dual approach. Third, we propose an iterative algorithm to obtain the joint sub-channel and power allocation strategies. Simulations results show that the proposed OFDMA-NOMA scheme performs better than the OFDMA-based scheme.

在本文中，我们研究了异构蜂窝网络中的下行链路资源分配和跨层干扰管理。为了进行跨层干扰控制，我们提出了一种基于正交频分多址（OFDMA）-非正交多址（NOMA）的方案，其中宏基站（MBS）仅使用基于OFDMA的子信道（OBSC），而总带宽（OBSC和基于NOMA的子信道（NBSC））可用于小型BS（SBS）。将资源分配问题表述为非凸NP硬优化问题，该问题共同设计子信道分配和功率分配，以使总速率性能最大化。为了降低计算复杂度，我们分三步解决了这个问题。首先，对于子通道分配，我们通过使用可用的在线优化求解器来解决凸问题。其次，我们将非凸功率分配问题近似为凸优化问题，并通过拉格朗日对偶方法获得功率分配策略。第三，我们提出了一种迭代算法来获得联合子信道和功率分配策略。仿真结果表明，所提出的OFDMA-NOMA方案比基于OFDMA的方案具有更好的性能。