Multiuser diversity can be used to significantly increase system throughput in wireless communication systems. The idea is to schedule users when they experience good channel conditions and let them wait when the channels are weak. In this thesis, several aspects on multiuser diversity OFDMA systems are investigated. An adaptive reduced feedback scheme for multiuser diversity OFDMA is proposed....

We study the performance of a UMTS downlink, as achieved by a single-user (RAKE) and a multiuser (linear MMSE) receiver with adaptive modulation and multicode in the presence of multipath fading. We advocate an adaptive transmission scheme that varies the number of virtual users and the modulation spectral efficiency in order to optimize the system throughput. Two multipath channel models are c...

With a narrowband multiuser detector (MUD), multiple users can simultaneously share the same channel without using a bandwidth expanding signature code when sufficient power differences at the receiver are maintained. In this paper we assess the capacity gain that can be achieved in a hypothetical cellular system with centralized power control, using a narrowband MUD based on successive cancell...

In this thesis, we evaluate the performance of multiuser detectors over an uplink using AWGN, Rayleigh flat fading single-input single-output (SISO) and multiple-input multiple-output (MIMO) channel models. First, we review the performance of three multiuser receivers; the decorrelator, the MMSE receiver and the multistage parallel interference cancellation receiver in an AWGN and Rayleigh flat...

The use of multiple antennas to improve the reliability and capacity of wireless communication has been around for a while, leading to the concept of multiple-input multiple-output (MIMO) communications. To enable full MIMO potentials, the precoding design has been recognized as a crucial component. This thesis aims to design multiuser MIMO precoders of practical interest to achieve high reliab...

The multiuser detection problem applies when we are sending data on the uplink channel from a handset to a base station. The base station must demodulate and decode signals from K−1 interfering handsets. A related problem known as interference cancellation arises on the down-link channel from the base station to the handset in which the handset must separate the signal intended for it, from the...

The presence of both multiple-access interference (MAI) and intersymbol interference (ISI) constitutes a major impediment to reliable communications in multipath code-division multiple-access (CDMA) channels. In this paper, an iterative receiver structure is proposed for decoding multiuser information data in a convolutionally coded asynchronous multipath DS-CDMA system. The receiver performs t...