Blind spreading factor detectors for DS-CDMA receivers. Part I: autocorrelation based detectors

The spreading factor (SF) in a code-division multiple-access system depends on the data rate of the user, and can therefore be unknown a priori for a communication receiver. A blind spreading factor detection problem is formulated. Suboptimal autocorrelation based SF detectors with different decision rules are analyzed and derived to find simple and robust detectors for practical communication receivers. The analysis is based on finding the statistics of the decision variable and then matching the decision rule to that.