Principles of Blind Equalization Algorithms and CMA Algorithm Implementation

This paper provides a detailed explanation of the principles behind blind equalization algorithms and the Constant Modulus Algorithm (CMA), accompanied by comprehensive simulation experiments using CMA for 4QAM signals. Blind equalization algorithms represent a channel estimation-based equalization approach that recovers original signals by estimating channel impulse responses. The CMA algorithm serves as a widely-used adaptive equalization technique that continuously adjusts equalizer weights through error function minimization to achieve signal equalization. In our simulation experiments, we implemented CMA equalization for 4QAM signals using algorithmic approaches that typically involve: - Initialization of tap weights with center-tap initialization method - Implementation of stochastic gradient descent for weight updates - Calculation of modulus error using the constant modulus criterion The performance evaluation examined post-equalization signal quality metrics including Bit Error Rate (BER) and Peak-to-Average Power Ratio (PAPR) through MATLAB-based simulation frameworks. The experimental results demonstrate that the CMA algorithm excels in equalizing 4QAM signals, effectively enhancing signal quality and transmission reliability through its robust convergence properties and modulus preservation characteristics.