Multitask deep learning-based multiuser hybrid beamforming for mm-wave orthogonal frequency division multiple access systems

Multiuser Diversity Orthogonal Frequency Division Multiple Access Systems

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....

Channel-independent synchronization of orthogonal frequency division multiple access systems

We develop synchronization algorithms for both the downlink and the uplink of quasi-synchronous and asynchronous orthogonal frequency division multiple access systems. Unlike existing alternatives, the proposed timeand carrier-offset estimators do not require the transmission of known sequences and exhibit performance independent of the underlying channel zero locations. The only necessary assu...

Distance-Aware Beamforming for Multiuser Secure Communication Systems

Typical cryptography schemes are not well suited for low complexity types of equipment, e.g., Internet of things (IoT) devices, as they may need high power or impose high computational complexity on the device. Physical (PHY) layer security techniques such as beamforming (in multiple antennas systems)  are possible alternatives to provide security for such applications. In this paper, we consid...

Adaptive codebook-based channel prediction and interpolation for multiuser multiple-input multiple-output-orthogonal frequency division multiplexing systems

In multiple-input multiple-output–orthogonal frequency division multiplexing (MIMO–OFDM) communications, the channel state information (CSI) of the forward link at each subcarrier is needed for precoder design at the transmitter to achieve the maximal diversity and/or multiplexing gains. In frequency division duplex (FDD) systems, the CSI needs to be estimated at the receivers and fed back to t...

Timing and frequency synchronization for orthogonal frequency division multiple-access systems