On the Refinement Method for Improving the Blind Estimation of Spreading Sequence

In non-cooperative contexts, such as electronic warfare, a receiver should estimate communication parameters without any prior knowledge of the transmitter. Especially in direct sequence spread spectrum (DSSS) systems, it is necessary to blindly estimate the spreading sequence for the recovery of information from the received DSSS signal. This task remains challenging due to the inherent low probability of intercept characteristics of DSSS signals. Accordingly, various blind estimation algorithms for spreading sequence have been studied. Although these algorithms show good estimation performance, there is still room for improvement. For a non-cooperative context, this paper proposes a refined method that can directly be applied to any conventional algorithm for the blind estimation of the spreading sequence for$M$-ary signal to improve estimation accuracy and analyzes its estimation performance. In this regard, we derive test statistics and decision rules which are designed to minimize the chip error rate of the spreading sequence. Through various computer simulations, we show that the proposed method improves estimation performance in terms of the chip error rate of the spreading sequence without a significant increase in computational complexity.