Iterative Demodulation and Channel Estimation for Asynchronous Joint Multiple Access Reception

Joint detection of asynchronous signal streams via iterative reception is investigated. While basic theoretical system performance is well understood, practical aspects such as those arising from time-varying channels due to parameter drifts are less well explored. The integration of adaptive estimators for these time-varying channels for all data streams into the iterative receiver processor is investigated and it is shown that relatively simple correlation-based estimators are sufficient to allow adequate tracking of the channels and achieve near-optimal performance of the receiver. The estimators are designed and studied via system convergence functions. The analytical results are verified with selected simulation examples.