Research on variable step-size CMA algorithm in mode-division multiplexing system

In order to solve the problem of contradiction between the convergence speed and steady-state error of the traditional Constant Modulus Algorithm (CMA) algorithm in channel equalization of Mode Division Multiplexing (MDM) system, a variable step-size CMA algorithm based on Sigmoid function, mode coupling theory and power coupling theory was proposed. In order to verify the optimization effect, a 6×6 mode-division multiplexing system model based on strong coupling was built by using the power coupling theory. the traditional CMA algorithm and the improved variable step-size algorithm were used to balance the data at the receiver. The results show that the improved variable step-size algorithm has a performance gain of 1.5dB compared with the traditional CMA algorithm when the FEC (Forward Error Correction) threshold is 3.8×10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−3</sup>, the average convergence speed and steady-state error of the six channels are gained.