大规模MIMO-OFDM系统下行链路非线性失真抑制问题是大规模MIMO-OFDM系统走向实用化的主要瓶颈之一。针对现有大规模MIMO-OFDM非线性失真抑制技术对系统的自由度利用不充分及使用单一的峰均比准则无法有效衡量非线性失真对系统性能影响的问题，本课题首先提出多维扰动空间的概念，通过建立通用信号扰动模型，分析不同扰动空间所具有的扰动自由度，来揭示基于多维空间扰动的大规模MIMO-OFDM非线性失真抑制机理；通过设计多准则约束下的多维非正交扰动非线性失真抑制优化方案和低复杂度的优化算法，来实现有效的非线性失真抑制。本研究不仅可以有效降低大规模MIMO-OFDM系统由于非线性失真所带来的性能损失问题，而且可以有效提升发端设备功率效率，为构建下一代大容量、高可靠的无线通信网的实用化提供必要的理论及技术支撑。

Nonlinear distortion mitigation for massive MIMO-OFDM downlink has been regarded as one of the main bottlenecks constraining the realization of massive MIMO-OFDM systems. The existing nonlinear distortion mitigation schemes do not exploit the freedom offered by massive MIMO-OFDM systems, and ignore the problem that nonlinear distortion cannot be measured effectively only by PAPR. Therefore, they cannot achieve the optimal overall performance. To overcome the drawbacks, the project first builds a general signal perturbation model with the concept of multi-dimensional perturbation space. Then, based on the general signal perturbation model, the project illuminates the mechanism of nonlinear distortion mitigation with multi-dimensional perturbation. Thirdly, the project proposes optimized multi-dimensional non-orthogonal perturbation based nonlinear distortion mitigation schemes with multiple metrics. Finally, optimization methods are developed with low complexity to accomplish effective nonlinear distortion mitigation. Through the basic research and key technologies investigated for massive MIMO-OFDM systems, we can expect to both improve the system performance and lower the energy cost.