1. An equalizer, comprising: a demodulator to receive a symbol vector; wherein the demodulator is for minimum mean-square-error successive-interference-cancellation (“MMSE-SIC”) to provide first information; a decoder to receive the first information to provide second information to the demodulator; wherein the decoder includes a first loop for internally iteratively processing the first information to provide the second information as a refined estimate of the first information; wherein the demodulator and the decoder are coupled to provide a second loop for feeding back the second information for iteratively refining the first information; and wherein the demodulator includes: a detection-cancellation block to receive the symbol vector to provide an equalized vector; a channel pre-processor block to receive an initial vector output of the detection-cancellation block for the symbol vector for a demodulating-decoding iterative sequence to provide a weight vector; wherein the channel pre-processor block provides an approximation using a fixed matrix to generate the weight vector; and wherein the detection-cancellation block receives the weight vector for equalization of the symbol vector in order to provide the equalized vector.