Compact constellation algorithm for blind equalization of QAM signals

A new algorithm is presented for the blind equalization of complex signals. This algorithm combines the benefits of the well-known reduced-constellation algorithm (RCA) and decision-directed algorithm (DDA). The contribution lies in the technique of incorporating the sliced symbols (outcome of the decision device) in the weight adaptation process. Unlike the RCA, where the reduced constellation contains only four symbol points, the proposed algorithms uses all symbols of the signal constellation by compacting them in some statistical manner. The steady-state characteristics of the proposed algorithm are demonstrated by way of simulations and are compared to those of RCA. It is observed that the new algorithm has a better steady-state performance than RCA.