Dispersive CDMA Channels Research Articles

A Low Complexity RLS-PASTd Algorithm for Blind Multiuser Detection in Dispersive CDMA Channels

For joint blind channel estimation and multiuser detection in direct-sequence code division multiple access (DS-CDMA) systems, a combined scheme is proposed, which couples the recursive least-squares (RLS) adaptations and the PASTd subspace tracking algorithm. A major advantage of the RLS-PASTd algorithm is that it admits an adaptive implementation with low computational complexity instead of singular value decomposition. Simulation results demonstrate the fast tracking capability and high steady-state estimation accuracy of the proposed algorithm in both the time-invariant and time-variant environments

Subspace training method for multiuser detectionin dispersive CDMA channel

A subspace training method is presented for multiuser detection in dispersive DS-CDMA channels with the presence of multiple access interference (MAI). By using a small number of training symbols of the desired user, the proposed method is computationally efficient and near-far resistant.

Subspace methods for blind joint channel estimation and multiuser detection in CDMA systems

Recently developed subspace techniques for blind adaptive multiuser detection are briefly reviewed first. In particular, blind methods based on signal subspace tracking for adapting linear multiuser detectors in AWGN CDMA channels are considered, as well as extensions of these techniques to frequency selective fading channels, dispersive channels, and antenna array spatial processing. In addition, subspacedbased nonlinear adaptive techniques for robust blind multiuser detection in nondGaussian ambient noise channels are also described. Several new techniques are then developed within the subspace framework for blind joint channel estimation and multiuser detection, under some specific channel conditions. These include l1r an adaptive receiver structure for joint multiuser detection and equalization in dispersive CDMA channels, l2r a subspace method for joint multiuser detection and equalization in unknown correlated noise, and l3r a method for joint interference suppression and channel tracking in timedvarying fading channels.