Joint channel and carrier offset estimation in CDMA communications

This paper addresses the problem of CDMA multiuser detection in the presence of unknown multipath channels and residual carriers. An analytic algorithm which provides closed-form channel and carrier offset estimates is proposed. The algorithm first converts the multiuser estimation problem into single-user problems, and then analytically solves the resulting nonlinear multivariate optimization problems utilizing a polynomial matrix projection property. The performance of the proposed algorithm is investigated through first-order perturbation analysis. We also calculate the Cramer-Rao bound to illustrate the efficiency of the new algorithm. The analyses are supported by computer simulations.