In this paper, we propose a coordinated pilot reuse (CPR) approach to reduce the pilot overhead for multi-cell massive multi-input multi-output transmission. Unlike the conventional multi-cell pilot reuse approach in which pilots can only be reused among different cells, the proposed CPR approach allows pilots to be reused among both inter-cell and intra-cell user equipments, and thus, pilot ov...

We compare the performance of channel estimators for single-carrier (SC) systems using frequency domain multiplexed (FDM) and time domain multiplexed (TDM) pilot schemes, in terms of total overhead (including pilots, cyclic prefix and unused subcarriers), the required power backoff for the power amplifier and the frame error rate (FER) in time-varying channels. Channel estimators using FFT in t...

Pilots till date are used only for transmitting a known sequence for synchronization. In such systems pilots and training sequences are transmitted with the same minimum power governed by the modulation scheme used in the data sub–carriers. It has been found that the pilots enjoy extra signal to noise power ratio than required to achieve the required performance. Hence it is advocated in this p...

In order to reduce the downlink training overhead of mmWave communications, we propose a novel beamforming strategy using uplink sub-6GHz channel and pilots that are sent from few active antennas. Specifically, design dual-input neural network architecture, called FusionNet, merge The proposed fusion model could intelligently adjust attention paid (by network) for by an mechanism. output Fusion...

INTRODUCTION According to Lopes [Lopes, L.L. (1987). Between hope and fear: The psychology of risk. Advances in Experimental Social Psychology, 20, 255-295] tolerance of risk may be governed by sensitivity to either the opportunities for gain or threats of loss involved. METHODS In the initial study, qualified pilots were presented with 36 written flight scenarios that varied in the levels of...

A peak to average power ratio (PAPR) reduction method is proposed that exploits the precoding or beamforming mode in WiMAX. The method is applicable to any OFDM/A systems that implements beamforming using dedicated pilots which use the same beamforming antenna weights for both pilots and data. Beamforming performance depends on the relative phase shift between antennas, but is unaffected by a p...

An adaptive threshold computation method for pilot symbol assisted iterative channel estimation in coded OFDM systems is considered. The proposed threshold computation method is based on calculating a particular threshold for each data packet in order to select the reliable decoder output symbols to improve the system bit error rate performance. The adaptive threshold computation approach utili...

In this work, novel physical layer security (PLS) schemes are proposed for orthogonal frequency-division multiplexing (OFDM) to secure both data and pilots in multiple-input multiple-output (MIMO) systems. The majority of previous studies focus on only securing the without considering used channel estimation. However, leakage state information (CSI) from a legitimate node an eavesdropper allows...

BACKGROUND Flying related transient Low Back Pain (LBP) among helicopter pilots is considered an occupational distress. OBJECTIVE To examine if exercise programs can alleviate transient LBP. METHODS Sixty-five helicopter pilots (92% males), all reporting flying related LBP, responded to an epidemiological survey and a long-term follow-up, 44.8 months later, comprising questions regarding tr...

Most current displays in general aviation (GA) environments employ, at best, relatively simple audio displays that do not fully exploit the operator’s sensory processing capabilities, and thus may not allow pilots to take full advantage of the available information. This paper describes a series of four experiments conducted in an actual flight environment at the USAF Test Pilot school that eva...