Efficient Expectation Propagation Massive MIMO Detector With Neumann-Series Approximation

Expectation propagation (EP) attains near-optimal performance for massive multiple-input multiple-output (MIMO) detection. However, the inevitable matrix inversions and exponentiations at each EP iteration bring great challenges to realistic hardware implementation. To address these issues, a low-complexity EP with iterative Neumann-series Approximation (EP-INSA) detector is proposed by employing INSA to estimate the inverse matrices. Further approximations are applied to avoid the exponentiations, which makes EP-INSA an efficient, feasible, and hardware-friendly detector for massive MIMO with various modulations. Simulation results show that EP-INSA attains similar performance as exact EP with only a few INSA terms, which assures enhanced performance and complexity trade-off. The associated hardware architectures of EP-INSA detector are also presented. The implementation results on 65 nm CMOS technology show that our design yields a throughput of 0.62 Gb/s with 2.63× area efficiency of existing EP detector.