Maximum likelihood estimation of pseudo-noise sequences in non-cooperative direct-sequence spread-spectrum communication systems

摘要

Maximum likelihood algorithm for blind estimation of spreading sequence in direct-sequence spread-spectrum (DSSS) signals is proposed. Although this algorithm has a high computational complexity, it gives the best estimation accuracy and it can determine the lower bound of spreading sequence estimation. Also, for small periods of the spreading sequence it may be used in practical systems. In order to reduce the computational complexity, another algorithm is proposed based on the Viterbi algorithm. This algorithm has a low computational complexity and its performance improves by increasing the period length of the spreading sequence.