On adaptive code division multiple access detectors

Abstract

Several variations of adaptive CDMA synchronous receiver schemes which can automatically adjust to the system parameters, are studied in this dissertation. Unlike their non-adaptive counterparts, these adaptive detectors require no knowledge of the received signals\u27 energies and have similar or better performance. Minimum energy and decorrelating criterion are used to update the weights. Since weights are updated according to the changes of the detector\u27s outputs, hence no training sequence is required. The convergences of some of the aforementioned adaptive detectors are also disscussed. The detectors proposed in this dissertation are near-far resistant,thus rendering the high-precision power control unnecessary. Among them, the two-stage adaptive detector with a soft tentative decision is worth mentioning. It combines the advantages of two different two-stage detectors and approaches the performance of the optimum detector, but with much less complexity