Code-aided blind rate detection for multirate DS/CDMA systems

The problem of rate detection for a multi-rate DS/CDMA systems is considered in this paper. It is assumed that, in each data-frame, each user may transmit its data at one out of a set of available data-rates, depending, e.g., on the kind of data to be transmitted, on the desired quality-of-service and on the channel state. Relying on the knowledge of the spreading codes of the user whose rate is to be detected, a rate detection algorithm based on the application of the generalized likelihood ratio test is here proposed. Both the cases where either the rates of the interfering users have been already detected and are known to the receiver or these rates are not known to the receiver are separately considered. Simulation results confirm that the proposed techniques achieve satisfactory performance levels.