A Digital Predistortion Scheme Exploiting Degrees-of-Freedom for Massive MIMO Systems
A Digital Predistortion Scheme Exploiting Degrees-of-Freedom for Massive MIMO Systems
复制标题
DOI：
10.1109/icc.2018.8422266
复制
发表时间：
2018-01
期刊：
影响因子：
--
通讯作者：
Miao Yao;Munawwar M. Sohul;R. Nealy;V. Marojevic;Jeffrey H. Reed
中科院分区：
文献类型：
--
作者：
Miao Yao;Munawwar M. Sohul;R. Nealy;V. Marojevic;Jeffrey H. Reed
无线发射机中非线性失真的主要来源是功率放大器（PA）。传统的数字预失真（DPD）方案使用高阶多项式来精确地近似和补偿PA的非线性。这对于在大规模多输入多输出（MIMO）系统中缩放到数十或数百个PA是不实际的。在大规模MIMO系统中，由于自由度（DoF）过多，存在多于一个的候选预编码矩阵，并且每个预编码矩阵需要不同的DPD多项式阶数来补偿PA非线性。本文提出了一种利用下一代前端的大量自由度实现的低阶DPD方法。我们提出了一种新的间接学习结构，通过级联自适应迫零预编码和DPD迭代地适应信道和PA失真。对于100×10大规模MIMO配置，我们的解决方案使用3阶多项式来实现与使用11阶多项式的传统DPD相同的性能。实验结果表明，计算复杂度降低了70%，实现了超低延迟通信。
The primary source of nonlinear distortion in wireless transmitters is the power amplifier (PA). Conventional digital predistortion (DPD) schemes use high- order polynomials to accurately approximate and compensate for the nonlinearity of the PA. This is not practical for scaling to tens or hundreds of PAs in massive multiple-input multiple-output (MIMO) systems. There is more than one candidate precoding matrix in a massive MIMO system because of the excess degrees-of- freedom (DoFs), and each precoding matrix requires a different DPD polynomial order to compensate for the PA nonlinearity. This paper proposes a low-order DPD method achieved by exploiting massive DoFs of next-generation front ends. We propose a novel indirect learning structure which adapts the channel and PA distortion iteratively by cascading adaptive zero forcing precoding and DPD. Our solution uses a 3rd order polynomial to achieve the same performance as the conventional DPD using an 11th order polynomial for a 100×10 massive MIMO configuration. Experimental results show a 70% reduction in computational complexity, enabling ultra-low latency communications.