Architecture design of a fast feed-forward blind equalizer with joint generalized multilevel modulus and low-cost soft decision directed scheme for cable modem receiver

Abstract

An architecture design of a fast feed-forward blind equalizer with a two-stage generalized multilevel modulus algorithm (GMMA) and low-cost soft decision-directed (SDD) scheme is developed for high-order QAM cable receivers on broadcasting downstream cable channels. The proposed fast blind equalization scheme uses a two-stage convergence strategy. Compared with the previous GMMA+SDD method, the low-cost SDD based scheme without division has the same equalization performances. At the SDD mode, the proposed low-cost exponential computation is realized by the pure arithmetic circuits without using any look-up-table, and the accuracy with the proposed exponential design is better than that with the traditional Taylor expansion method. On the wired cable channel at 64, 256, and 1024QAM modes, the proposed low-cost blind equalization architecture has a faster convergence speed than previous blind methods. The proposed low-cost scheme also achieves a smaller MSE than the other methods at the same signal-to-noise ratio (SNR).