Threshold optimization for ISI-free region detection in high-mobility fading channels

2015 ◽  
Author(s):  
Chenchen Zhang ◽  
Xuejun Chen ◽  
Yuan Luo
Keyword(s):  
Fading Channels ◽  
High Mobility ◽  
Region Detection ◽  
Threshold Optimization ◽  
Free Region

scholarly journals Non-coherent massive MIMO-OFDM for communications in high mobility scenarios

2020 ◽  
Vol 1 (1) ◽  
pp. 13-24
Author(s):  
Kun Chen-Hu ◽  
Yong Liu ◽  
Ana Garcia Armada
Keyword(s):  
Fading Channels ◽  
Orthogonal Frequency Division Multiplexing ◽  
High Mobility ◽  
Coherent Demodulation ◽  
Hardware Impairments ◽  
Single Carrier ◽  
High Power Amplifier ◽  
Reference Signals ◽  
Mimo Ofdm ◽  
The Impact

Under scenarios of high mobility, the traditional coherent demodulation schemes (CDS) have a limited performance, due to the fact that reference signals cannot effectively track the variations of the channel with an affordable overhead. As an alternative solution, non coherent demodulation schemes (NCDS) based on differential modulation have been proposed. Even in the absence of reference signals, they are capable of outperforming the CDS with a reduced complexity. The literature on NCDS laid the theoretical foundations for simplified channel and signal models, often single carrier and spatially uncorrelated flat fading channels. In this work, the most recent results assuming orthogonal frequency division multiplexing (OFDM) signaling and realistic channel models are explained, and the impact of some hardware impairments such as the phase noise (PN) and the non linear high power amplifier (HPA) are also considered. Moreover, new potential research lines are also highlighted.

A TEM study of the effect of oxygen on nanocavity formation and precipitation in rapid - solidified Fe-16Ni-9Cr stainless steels

1994 ◽  
Vol 52 ◽  
pp. 700-701
Author(s):  
S. Wisutmethangoon ◽  
T. F. Kelly ◽  
J.E. Flinn
Keyword(s):  
Stainless Steels ◽  
High Mobility ◽  
Hot Extrusion ◽  
Extrusion Ratio ◽  
Gas Atomization ◽  
Cavity Formation ◽  
Nucleation Sites ◽  
Heat Treated ◽  
Different Types ◽  
Effect Of Oxygen

Vacancies are introduced into the crystal phase during quenching of rapid solidified materials. Cavity formation occurs because of the coalescence of the vacancies into a cluster. However, because of the high mobility of vacancies at high temperature, most of them will diffuse back into the liquid phase, and some will be lost to defects such as dislocations. Oxygen is known to stabilize cavities by decreasing the surface energy through a chemisorption process. These stabilized cavities, furthermore, act as effective nucleation sites for precipitates to form during aging. Four different types of powders with different oxygen contents were prepared by gas atomization processing. The atomized powders were then consolidated by hot extrusion at 900 °C with an extrusion ratio 10,5:1. After consolidation, specimens were heat treated at 1000 °C for 1 hr followed by water quenching. Finally, the specimens were aged at 600 °C for about 800 hrs. TEM samples were prepared from the gripends of tensile specimens of both unaged and aged alloys.

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