Spreading Sequence Blind Estimation in DSSS System Using Gradient Ascent Method

Abstract

In direct sequence spread spectrum systems, a receiver must know the spreading code to despread a signal. In non-cooperative contexts, there is no prior information about the spreading code, and it must be blindly estimated. Generally, the maximum likelihood-based method is known to show optimal performance in terms of estimation accuracy, but its computational complexity hinders its practicality. In this paper, we present an estimation algorithm for the spreading sequence that reduces the computational complexity of the maximum likelihood-based algorithm by using the gradient ascent method. To validate the proposed method, we compare the estimation performance of the proposed algorithm with that of an existing method in terms of their computational complexity and the error rate of a chip in the estimated spreading sequence.