A novel dynamic hybrid beamforming architecture is proposed to achieve the spatial multiplexing-power consumption tradeoff for near-field multiple-input multiple-output (MIMO) networks, where each radio frequency (RF) chain is connected to each antenna using a couple of independent phase shifters to reduce the number of required RF chains. Based on this architecture, an optimization problem is formulated that maximizes the sum of achievable rates while minimizing the hardware power consumption. Both continuous and discrete phase shifters are considered. 1) For continuous phase shifters, a weighted minimum mean-square error-based two-stage (WMMSE-TS) algorithm is proposed, where the same performance as the optimal fully-digital beamformer can be achieved by the proposed hybrid beamformer even if the number of RF chains equals the number of data streams. 2) For discrete phase shifters, a penalty-based layered iterative (PLI) algorithm is proposed. The closed-form analog and baseband digital beamformers are derived in each iteration. Simulation results demonstrate that: 1) the proposed dynamic beamforming architecture outperforms the conventional fixed hybrid beamforming architecture in terms of spatial multiplexing-power consumption tradeoff, and 2) the proposed algorithms achieve better performance than the other baseline schemes.

翻译：针对近场多输入多输出（MIMO）网络中空间复用与功耗的权衡问题，本文提出一种新型动态混合波束赋形架构。在该架构中，每条射频（RF）链通过一组独立的移相器连接至各天线单元，从而减少所需射频链数量。基于该架构，建立了一个以最大化可达速率总和与最小化硬件功耗为目标的优化问题，并分别考虑连续移相器与离散移相器两种情况：1）对于连续移相器，提出基于加权最小均方误差的两阶段（WMMSE-TS）算法。该混合波束赋形器在射频链数量等于数据流数量的情况下，仍能达到与最优全数字波束赋形器相同的性能。2）对于离散移相器，提出基于惩罚因子的分层迭代（PLI）算法，并在每次迭代中推导出模拟域与基带数字域波束赋形器的闭式解。仿真结果表明：1）所提出的动态波束赋形架构在空间复用-功耗权衡方面优于传统固定混合波束赋形架构；2）所提算法在性能上优于其他基准方案。