For high performance CDMA communications, multiuser detection is often required to suppress the multiple access interference (MAI). Most multiuser detectors rely on accurate channel information to recover the multiuser digital signals. This paper studies the blind channel estimation problem for DS-CDMA systems using aperiodic spreading codes. The Maximum Likelihood (ML) estimator is formulated ...

In this paper we propose a novel multiuser detector for the synchronous CDMA system. Its BER performance approaches to the optimum MMSE multiuser detector while the complexity only polynomially increases to the number of active users. We also demonstrate its complexity and performance over optimnm MMSE multiuser detector and decorrelator. In addition to synchronous AWGN channel case, we also pr...

In multiuser MIMO networks, the spatial degrees of freedom offered by multiple antennas can be advantageously exploited to enhance the system capacity, by scheduling multiple users to simultaneously share the spatial channel. This entails a fundamental paradigm shift from single user communications, since multiuser systems can experience substantial benefit from channel state information at the...

A blind Adaptive Space-Time Lifted Multiple-Input Multiple-Output (ASTL-MIMO) multiuser receiver is proposed for multipath MIMO channel estimation and multiuser detection of MIMO DS-CDMA systems in a realistic outdoor channel. An iterative and robust ASTL-MIMO Beamformer is employed to estimate the multipath MIMO channel parameters. For each iteration, the tracking mode with consideration of MI...

Multiuser detection in Code Division Multiple Access systems usually requires either knowledge of the transmitted signature sequences and channel state information or use of a known training sequence for adaptation. In this paper we develop a scheme that can be employed for the joint adaptive blind multiuser identification and detection in asynchronous CDMA systems. This scheme relies on a mult...

We propose a low complexity iterative multiuser decoder. We perform the multiuser a-posteriori probability calculation based on the marginalization of probabilities over a subset of the P highest probable sequences. Given a K user symmetric channel this list may be approximated closely with per-bit computational complexity O K P 2K logK . We further show that for any multiuser system possessing...

Multiuser diversity, as a fundamental property for fading wireless networks, has been widely applied in today’s wireless communication systems. Conventionally, due to the multiuser diversity, the long-term throughput of a wireless system consisting of multiple independently fading communication links can be enhanced by selecting one link with the best instantaneous channel quality to transmit a...

In this paper, we address the problem of improving the performance of multiuser space-division multiplexing (SDM) systems where multiple independent signal streams can be transmitted in the same frequency and time slot. The problem is important in multiuser multiple-input multiple-output systems where communication from one base station to many mobile stations can occur simultaneously. Our obje...

In this paper, a pilot assisted minimum mean square error multiuser channel estimation algorithm is proposed for quasi-synchronous CDMA systems. The doubly selective multiuser fading channel is represented as a time-varying chip-spaced tapped delay line filter with correlated filter taps. The multiuser channel tap coefficients at pilot symbol positions are estimated under the MMSE criterion wit...

In this paper, we present different linear and nonlinear iterative data detection schemes for the asynchronous direct-sequence code-division multiple access (DS-CDMA) systems employing orthogonal signalling formats and long scrambling codes. Compared to the conventional receiver and other noncoherent multiuser detectors, coherent multiuser detection schemes achieve much better performance provi...