基于多路实值时延神经网络的大规模MIMO系统发射机射频失真补偿方案

Radio Frequency Distortion Compensation Scheme of Massive MIMO System Transmitter Based on Multi-channel Real-Valued Time-delay Neural Network

  • 摘要: 大规模MIMO(Multiple-Input Multiple-Output)系统具有频谱效率高、系统容量大的优势。然而由于发射机射频元件存在着技术、工艺等方面的限制,大规模MIMO系统不可避免地存在着多种射频失真问题,成为制约系统性能的重要瓶颈。本文针对大规模MIMO系统中的功率放大器 (Power Amplifier,PA)非线性、同相/正交 (In-phase/Quadrature,I/Q)支路不平衡、射频链路串扰等多种射频失真问题,提出基于多路实值时延神经网络(Real-Valued Timed-Delay Neural Network, RVTDNN)的大规模MIMO系统发射机射频失真补偿方案。该方案使用多个RVTDNN预失真网络对发射信号进行预处理,补偿发射机的射频不理想特性,提高系统性能。此外,本文还提出了基于量子遗传算法的预失真网络超参数优化方案,与传统的基于遗传算法的网络超参数优化方案相比,该方案在种群数较小时可实现超参数优化,从而降低了算法的时间复杂度。

     

    Abstract: Massive MIMO (Multiple-Input Multiple-Output) system has the advantages of high spectrum efficiency and large system capacity. However, due to the limitation of technique and manufacture in transmitter's radio frequency components, massive MIMO systems inevitably have many serious radio frequency distortion problems, which have become an important bottleneck restricting the system performance. This article focuses on the radio frequency distortion problems of power amplifier (PA) nonlinearity, in-phase/quadrature (I/Q) branch imbalance, and RF link crosstalk in massive MIMO systems. The RF distortion compensation scheme of massive MIMO system transmitter based on Multi-channel Real-Valued Timed-Delay Neural Network (RVTDNN) is proposed. This scheme uses multiple RVTDNN predistortion networks to pre-process the transmitted signal, compensate for the undesirable radio frequency characteristics of the transmitter, and improve system performance. In addition, this paper also proposes a predistortion network hyperparameter optimization scheme based on quantum genetic algorithm. Compared with the traditional genetic algorithm-based network hyperparameter optimization scheme, this scheme can obtain the optimal solution with small population number and low time complexity.

     

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