低精度ADC下大规模多输入多输出系统基于三对角迭代法的软输出信号检测
Soft Output Signal Detection for Massive Multiple Input Multiple Output Systems with Low-resolution ADC Based on Tridiagonal Iterative Method
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摘要: 受硬件成本制约，大规模多输入多输出（massive Multiple Input Multiple Output， mMIMO）基站通常配置低精度模数转换器（Analog-to-Digital Converter， ADC）。低精度ADC下，如果多用户mMIMO系统采用最小均方误差（Minimum Mean Square Error， MMSE）检测，将导致过高复杂度。为此，本文基于三对角迭代法（Tridiagonal Iterative Method， TDIM），结合分块矩阵求逆的初始值确定，提出一种低复杂度的MMSE软输出信号检测算法。数值仿真表明：基于TDIM的软输出信号检测算法经4次迭代即可达到收敛，同时，数值结果验证了ADC量化比特为4时，该算法可取得接近全精度ADC的性能，为低精度ADC下mMIMO系统的上行链路信号检测实现提供了切实可行的方案。Abstract: Due to the limitation of hardware cost， massive multiple input multiple output （mMIMO） base stations are usually equipped with low-resolution analog-to-digital converter （ADC）. The complexity of Minimum Mean Square Error （MMSE） detection is too high to realize in multiuser mMIMO systems with low-resolution ADC. Therefore， to reduce the complexity of the soft output signal detection and achieve a near-optimal performance， in this paper， a low complexity MMSE soft output detection algorithm is proposed which based on tridiagonal iterative method （TDIM） and the block-matrix-inversion based initial solution. The numerical results verify that the TDIM-based soft output signal detection algorithm takes 4 iterations to converge and approximates the performance of Cholesky algorithm when the MMSE filtering matrix is diagonally dominant. The performance of mMIMO system with a 4-bits-ADC is close to the full resolution ADC as well， which provides a feasible solution for the uplink soft output signal detection of mMIMO systems with low-resolution ADC.
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