Performance Comparison of ZF and MMSE Linear Detectors in MIMO Systems Under Rayleigh Fading

Abstract

Multiple-input multiple-output (MIMO) technology is widely adopted in modern wireless communication systems to enhance transmission rate and link reliability. Linear detection algorithms are popular MIMO receivers due to their moderate computational complexity. This paper comprehensively investigates the bit error rate (BER) performance of two classic linear detectors, namely zero-forcing (ZF) and minimum mean-squared error (MMSE), over Rayleigh fading channels. A series of Monte Carlo simulations are carried out under diverse system configurations, including different MIMO antenna scales, quadrature amplitude modulation (QAM) schemes and varying signal-to-noise ratios. We first compare the performance of 2×2 MIMO with 16QAM and 4×4 MIMO with 4QAM. Furthermore, the influence of the number of receive antennas on detection performance is analyzed in detail. Simulation results demonstrate that MMSE detector outperforms ZF detector across all test scenarios, as it effectively suppresses the noise amplification effect existing in ZF detection. Increasing the number of receive antennas can bring considerable diversity gain and greatly reduce system BER. In addition, larger antenna arrays combined with low-order modulation can achieve better communication reliability. This work reveals the trade-off among antenna configuration, modulation mode and detection scheme, and provides valuable references for the practical design of MIMO wireless systems.