Channel acquisition and tracking for the uplink of a code-division multiple-access system

This paper investigates channel acquisition and tracking for the uplink of a DS-CDMA system. The transmission medium is characterized by multipath propagation and the goal is the estimate the time-varying channel impulse response (CIR) of a new user entering the system. Channel acquisition is pursued through maximum likelihood techniques while channel tracking is performed through weighted least squares methods. At each signaling interval the CIR estimate the inverse of the interference covariance matrix to mitigate the near-far problem. Performance is assessed by simulation in a scenario inspired by the UMTS system.