Abstract: This paper focuses on the appliance of multiuser detection algorithm based on belief propagation (BP) in MIMO systems with M-QAM(Quadrature Amplitude Modulation) modulation scheme. Because of the characteristics of M-QAM modulation, this paper introduces a preprocess to eliminate the correlation between the elements of receiving signal vector, proposes to take a conditional probability vector as the measurement of “belief” of transmitting signal, deduces the corresponding formulae of belief-updating and thus constructs the BP-Based MUD algorithms in MIMO systems with M-QAM modulation scheme. The algorithm proposed in this paper has a computation complexity proportional to the square of transmitting antenna number while it outperforms the conventional linear MMSE multiuser detector. Simulation results are given to prove this.

Key words: multiple-input multiple-output, belief propagation, multiuser detection, M-QAM modulation

摘要： 研究了基于置信度传播的多用户检测算法在采用M-QAM(Quadrature Amplitude Modulation)调制的MIMO系统中的应用。针对多进制调制的特点，引入预处理模块以消除接收信号矢量各个分量之间的相关性，提出采用条件概率矢量作为发送信号的置信度，并随后推导了相应的置信度传播的公式，从而实现了多进制调制下基于置信度传播的多用户检测算法。该算法的计算复杂度与用户数目的平方成正比，性能则优于传统的线性MMSE多用户检测器，给出的仿真结果证明了这一点。

关键词: 置信度传播, 多用户检测, M-QAM调制, 多入多出