A hierarchic maximum likelihood method for delay estimation in CDMA

CDMA (code division multiple access) is a multiple access technique based on spread spectrum methods. To estimate the delay parameters appearing in the data model, several authors have proposed subspace-based solutions. Unfortunately, these methods, for example the eigenvector-based MUSIC method fail at low signal-to-noise ratios. On the other hand, theoretically optimal maximum likelihood method is computationally too demanding in practice. In this work, we introduce a hierarchic way to construct a maximum likelihood approximation for delay estimation. Simulations show that the new method outperforms standard MUSIC