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您的检索式：作者名="CHAOKAI YANG"
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| 1 | Refocusing of the optical branched flow on a rough curved surface显示文摘The phenomenon of branched flow has attracted researchers since its inception,with recent observations of the light branching on soap bubbles.However,previous studies have primarily focused on the flat spacetime,overlooking the effect of surface curvature on branched flows.In this paper,we explore the branched flow phenomenon of light on a rough curved surface called constant Gaussian curvature surfaces(CGCSs).Compared with flat space,a CGCS demonstrates that the first branching point advances due to the focusing effect of the positive curvature of the surface.Furthermore,unlike on flat space,optical branches on curved surfaces do not consistently become chaotic during its transmission in a random potential field.On the contrary,the“entropy”decreases at specific positions,which reveals a sink flow phenomenon following the generation of branched flows.This result highlights the time inversion characteristics of CGCSs.Lastly,we demonstrated that the anomalous entropy reduction is related to the transverse and longitudinal coherence transformations of light.We suppose these efforts would fuel further investigation of the thermodynamic evolution and spatiotemporal inversion of random caustics,as well as their future application in the information transmission of random potentials in curved spacetime. | WEIFENG DING ZHAOYING WANG CHAOKAI YANG | 2023 | Photonics Research2023，11，12： | 0 |
| 2 | Low-Cost Massive MIMO:Pilot Length and ADC Resolution显示文摘When designing an energy efficient massive multiple-input multiple-output(MIMO)system where each receiver antenna is equipped with a low-resolution analog-to-digital converter(ADC),the number of base station(BS)antennas and quantization bits are generally two mutually conflicting system parameters.In this paper,we investigate the joint optimization of the number of BS antennas and ADC resolution in quantized massive MIMO systems,assuming imperfect channel state infor-mation(CSI).A tractable approximate expression for the uplink sum spectral efficiency(SE)using maximal ratio combining(MRC)receivers is derived,based on which the pilot length which maximizes the sum SE is put forward.Considering the effect of ADCs,a realistic model of total power consumption is given subsequently.Capitalizing on it,we formulate the optimization problem of selecting the number of BS antennas and ADC resolution to maximize the sum SE under a total power consumption constraint.Our results show that more pilot symbols should be assigned for massive MIMO systems with low-resolution ADCs,especially for the receivers with one-bit quantizers.Moreover,the results show the trade-off between the number of BS antennas and quantization bits.Numer-ical results suggest that there exists an optimal ADC resolution in massive MIMO systems,while lower quan-tization bits may cause a substantial degradation of the SE performance and higher one will consume more power. | Dan Qiao Xi Yang Weiqiang Tan Chaokai Wen Shi Jin | 2018 | Journal of Communications and Information Networks2018，3，2： | 0 |
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