SUMMARYThis paper considers the joint design of OFDM and code division multiple access (CDMA) with MIMO communications. The receivers for both Bell Labs Layered Space Time system and space–time block code are designed in this paper. The performances of the MIMO‐OFDM‐CDMA receivers are investigated in several typical fading channels. The maximum likelihood, zero forcing, and minimum mean square error receivers for the MIMO‐OFDM‐CDMA systems are derived, and the performances in the typical fading channels are verified by the simulations. Copyright © 2012 John Wiley & Sons, Ltd.

For direct-sequence code-division multiple-access (DS/CDMA) systems, the multiuser and multipath interferences are always present. When the demodulation is coherent, a coherent carrier reference must be generated prior to demodulation. The generation of coherent reference at low signal-to-interference-and-noise ratio (SINR) is difficult. In the downlink CDMA communications, numbers of active Users transmit information simultaneously by different signature waveform. However. the multipath channel and multiple-access interference (MAI) limit the system capacity. Adaptive single-user receivers do not require knowledge of MAI parameters and need fewer computations. In this paper. we propose adaptive receivers with decision-feedback differential detection (DF-DD) and compare variations of the receiver structure proposed in Schrober's paper for noncoherent channels. In the absence of knowledge of the carrier phase, we derive the minimum mean square error (MMSE) of the proposed receivers to show that the performances of the proposed receivers with M-ary differential phase-shift keying (MDPSK) signals approach that of the coherent receiver with MPSK signal. Some simulation examples are given to demonstrate the effectiveness and compare the performances of the proposed adaptive receivers. Copyright (C) 2008 John Wiley & Sons, Ltd

SummarySingle carrier‐frequency division multiple access (SC‐FDMA) has been adopted as the uplink transmission standard in fourth generation cellular network to enable the power efficiency transmission in mobile station. Because multiuser MIMO (MU‐MIMO) is a promising technology to fully exploit the channel capacity in mobile radio network, this paper investigates the uplink transmission of SC‐FDMA systems with orthogonal space frequency block codes (SFBC). Two linear MU‐MIMO receivers, orthogonal SFBC (OSFBC) and minimum mean square error (MMSE), are derived for the scenarios with limited number of users or adequate receive antennas at base station. In order to effectively eliminate the multiple access interference (MAI) and fully exploit the capacity of MU‐MIMO channel, we propose a turbo MU‐MIMO receiver, which iteratively utilizes the soft information from maximum a posteriori decoder to cancel the MAI. By the simulation results in several typical MIMO channels, we find that the proposed MMSE MU‐MIMO receiver outperforms the OSFBC receiver over 1 dB at the cost of higher complexity. However, the proposed turbo MU‐MIMO receivers can effectively cancel the MAI under overloaded channel conditions and really achieve the capacity of MU‐MIMO channel. Copyright © 2014 John Wiley & Sons, Ltd.

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