We present a new method of beamforming using the fractional Fourier transform (FrFT). This method encompasses the conventional minimum mean-squared error (MSE) beamforming in the frequency domain or spatial domain as special cases. It is especially useful for applications involving chirp signals such as signal enhancement problems with accelerating sinusoidal sources where the Doppler effect ge...

In this paper, we present an overlapped channel transmission (OCT) multiple access scheme which increases the uplink capacity of the slow FHMA systems. By using antenna arrays techniques, subscribers can transmit data through timefrequency overlapped slots and the proposed system increases the spectrum efficiency. A practical system that uses 2-fold OCT to increase system capacities with the sa...

In this paper, we propose a novel limited feedback approach for MIMO systems with transmit beamforming over time-varying channels, where the optimal beamforming vector of the current frame is selected from the son-codewords of the codewords neighboring to previous beamforming codeword. The proposed approach exploits the channel temporal correlation to improve the CSI quantized precise. The simu...

The problem of enhancing speech degraded by uncorrelated additive noise, when the noise speech alone available, has recently received much attention. Beamforming is one possible method of speech enhancement, because, the beamformer minimizes the output signal power but maintains signals from the desired direction. Beamforming techniques basically approach the problem from a spatial point of vie...

The performance of cooperative diversity with opportunistic beamforming is analyzed in rayleigh fading channels. Cooperative communication is viewed as a method for increasing diversity gain and reducing end to end path loss. The use of relays can create a virtual antenna array so that it allows users to exploit the advantages of multiple input multiple output (MIMO) techniques. In this paper w...

This paper deals with direction of sound wave arrival determination using time-delay estimation and beamforming methods with utilization of static microphone array with fixed geometry configuration. Theoretical part describes main principle of both methods and possibility of program implementation. Experimental part proposes hardware design of the sensory systems separately for time-delay estim...

A beamforming array is investigated for use in a radar system that is part of a hybrid acoustic/electromagnetic technique for detecting land mines. The radar is used to measure the surface displacement of the earth due to acoustic waves in the earth. The beamforming array is used to obtain small spatial resolution for the measurement of the displacement while allowing an adequate stando distanc...

The next fifth generation (5G) of wireless communication networks comes with a set of new features to satisfy the demand of data-intensive applications: millimeter wave frequencies, massive antenna arrays, beamforming, dense cells, etc. In this paper, we investigate the use of beamforming techniques through various architectures and evaluate the performance of 5G wireless access networks, using...

The focus of this work is on the analysis of transmit beamforming schemes with a low-rate feedback link in wireless sensor/relay networks, where nodes in the network need to implement beamforming in a distributed manner. Specifically, the problem of distributed phase alignment is considered, where neither the transmitters nor the receiver has perfect channel state information, but there is a lo...

This paper addresses the joint robust power control and beamforming design of a linear multiuser multiple-input multiple-output (MIMO) antenna system in the downlink where users are subjected to individual signal-to-interference-plus-noise ratio (SINR) requirements, and the channel state information at the transmitter (CSIT) with its uncertainty characterized by an ellipsoidal region. The objec...