Blind MMSE-based receivers for rate and data detection in variable-rate CDMA systems

In this paper the problem of rate detection for a variable data rate code division multiple access (CDMA) system is addressed. A multiuser scenario is considered wherein each user may transmit at one out of a set of possible data rates in each data-frame. In particular a data rate and information symbol detection strategy based on the use of a bank of linear minimum mean square error (MMSE) filters is here proposed; as many filters as the number of available data rates are considered and a decision on the estimated data rate is taken based on rate matched to the filter with the minimum mean output energy (MOE). Analytical expressions for the MOE are derived in order to give theoretical grounds to our detection strategy; moreover, the effectiveness of the proposed detection strategy is also validated through simulation results that show satisfactory performance levels.