Low Complexity High Resolution Joint Timing and Doppler Acquisition for DS-CDMA Systems

This paper presents a novel low complexity high resolution timing and Doppler acquisition algorithm for direct-sequence code division multiple access (DS-CDMA) systems. We apply the two-dimensional unitary estimation of signal parameters via rotational invariant techniques (ESPRIT) algorithm to the joint delay and Doppler acquisition task in multipath environments. Additionally, we use the advantageous beam space (BS) implementation of unitary ESPRIT, which reduces the computational complexity once again remarkably. The exploitation of a-priori knowledge according to the BS version of unitary ESPRIT also reduces the root mean square error (RMSE) at low signal to noise ratios (SNRs). Furthermore, we enhance the delay and Doppler multipath acquisition by the two-dimensional structured least squares (SLS) algorithm. Thus, our delay and Doppler RMSE reaches the Cramer-Rao bound (CRB) almost as good as maximum likelihood (ML) delay and Doppler acquisition. However, our algorithms save computational complexity compared to the ML algorithm by several orders of magnitude.