Cramer-Rao bound for joint direction of arrival, time delay estimation in DS-CDMA systems

In direct-sequence code-division multiple access (DS-CDMA) radiolocation systems, the estimation of propagation time delay and direction of arrival (DOA) is a crucial task. It can also be used for acquisition and tracking. To evaluate the accuracy of the estimated parameters, this paper derived the conditional Cramer-Rao bound (CRB) for the joint estimator of propagation time delay and DOA in asynchronous DS-CDMA systems. No knowledge of the transmitted bits is required. Simple asymptotic expressions of the CRB are presented. In the numerical study, the CRB and the simulation results of a subspace-based joint estimator are presented. Both CRB and the estimator are shown to be robust against near-far effect in CDMA systems with multiple users