Soft Output Signal Detection for Massive Multiple Input Multiple Output Systems with Low-resolution ADC Based on Tridiagonal Iterative Method

‍ ‍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.