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On Adaptive Code Division Multiple Access Detectors, Wenping Chen

Dissertations

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' 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's 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, …

Soft Decision Adaptive Multiuser Cdma Detector For Asynchronous Awgn Channels, Frank Viehofer

Theses

A multiuser detector in an asynchronous, additive white Gaussian noise, codedivision multipleaccess (CDMA) channel is proposed and analyzed. It employs a combination of a decorrelator and a nonlinear multiuser interference canceler that utilizes soft tentative decisions. The weights of the canceler are adaptively adjusted, in a manner that renders the knowledge of received signal energies and the use of training sequences unnecessary. The steady state error performance of the detector is obtained and found to be superior to the performance of the same detector that utilizes hard tentative decisions.