1. A method for estimating data received from a plurality of data signals in a code division multiple access communication system, the data signals transmitted in a shared spectrum at substantially a same time, the method comprising: receiving and sampling a combined signal of the transmitted data signals over the shared spectrum; estimating a channel response for the transmitted data signals; and estimating data of the data signals using the samples, the estimated channel response and a fourier transform based data estimation approach and iteratively reducing an error in the data estimation introduced from a circulant approximation used in the fourier transform based approach.