Blind and Training-Assisted Subspace Code-Timing Estimation for CDMA with Bandlimited Chip Waveforms

摘要

In this paper, we present a group of subspace codetimingrnestimation algorithms for asynchronous code-divisionrnmultiple-access (CDMA) systems with bandlimited chip waveforms.rnThe proposed schemes are frequency-domain based techniquesrnthat exploit a unique structure of the received signal inrnthe frequency domain. They can be implemented either blindlyrnor in a training-assisted manner. The proposed blind codetimingrnestimators require only the spreading code of the desiredrnuser, whereas the training-assisted schemes assume the additionalrnknowledge of the transmitted symbols of the desiredrnuser. Through a design parameter of user choice, the proposedrnschemes offer flexible tradeoffs between performance, user capacity,rnand complexity. They can deal with both time- andrnfrequency-selective fading channels. Numerical simulations showrnthat the proposed schemes are near-far resistant, and comparernfavorably to an earlier subspace code-timing estimation schemernthat is implemented in the time domain.