The explosive growth of innovative applications imposes great challenges for future wireless communication systems with respect to ultra-high spectrum and power efficiency. Non-orthogonal multiple access (NOMA) and multiple-input-multiple-output (MIMO) have been acknowledged as two promising spectral-enhancing techniques to address the aforementioned issues. Orthogonal space-time block code (STBC), on the other hand, is capable of exploiting the full diversity gain of MIMO system. In this work, we explore how STBC can be utilized to enhance the performance of two-cell MIMO-NOMA networks. To this end, an uplink power minimization problem for the two-cell STBC-aided MIMO-NOMA system is investigated, wherein the joint detection technique is adopted to boost the cell-edge user's performance. The formulated optimization problem is non-convex and is intractable to be solved directly. A two-tier methodology is applied to decompose the original problem into two sub-problems, namely the beamforming design and the power allocation. Specifically, for the beamforming design, a closed-form expression is derived based on the Gram matrix of channel matrix. In the meanwhile, an efficient iterative method is developed to determine the power allocation coefficients for both the cell-center and the cell-edge users. Simulation results reveal that the proposed scheme outperforms several golden baselines in terms of total power consumption.

中文翻译：

---

基于STBC和联合检测的高功率效率上行MIMO-NOMA系统设计

在超高频谱和功率效率方面，创新应用的爆炸性增长对未来的无线通信系统提出了巨大的挑战。非正交多路访问（NOMA）和多输入多输出（MIMO）已被公认为解决上述问题的两种有希望的频谱增强技术。另一方面，正交空时分组码（STBC）能够利用MIMO系统的全部分集增益。在这项工作中，我们探索如何利用STBC来增强两小区MIMO-NOMA网络的性能。为此，研究了用于两小区STBC辅助的MIMO-NOMA系统的上行链路功率最小化问题，其中采用联合检测技术来提高小区边缘用户的性能。制定的优化问题是非凸的，难以直接解决。应用两层方法将原始问题分解为两个子问题，即波束成形设计和功率分配。具体地，对于波束成形设计，基于信道矩阵的格拉姆矩阵来导出闭式表达式。同时，开发了一种有效的迭代方法来确定小区中心和小区边缘用户的功率分配系数。仿真结果表明，该方案在总功耗方面优于几个黄金基准。对于波束成形设计，基于信道矩阵的Gram矩阵推导闭式表达式。同时，开发了一种有效的迭代方法来确定小区中心和小区边缘用户的功率分配系数。仿真结果表明，该方案在总功耗方面优于几个黄金基准。对于波束成形设计，基于信道矩阵的Gram矩阵推导闭式表达式。同时，开发了一种有效的迭代方法来确定小区中心和小区边缘用户的功率分配系数。仿真结果表明，该方案在总功耗方面优于几个黄金基准。