New DFE with Phase-Locked Loop

Abstract

In [1] the decision feedback equalizer (DFE) based on constant modulus algorithm (CMA) and decision directed (DD) adaptive algorithm was proposed. It has been proved that it is much more effective than the conventional DFEs such as DFE based on CMA and DFE based on DD. However when Doppler frequency shift occurs in the communication channel, which can result in carrier phase rotation, the decisions precision is very low which degrades the performance of these DFEs. Consequently based on the DFE in [1] a new DFE with phase-looked loop (PLL) is proposed. The PLL works in CMA part which can offer correct decision for DD, so the proposed method can obtain lower steady state MSE and compensate phase rotations. The efficiency of the method is proved by computer simulation.