On the Design of High Power Efficiency Uplink MIMO-NOMA Systems: A STBC and Joint Detection Perspective

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.

Automated summary

The article explores how STBC technology can enhance the performance of two-cell MIMO-NOMA networks, involving joint detection techniques, power allocation, and beamforming design.