University of Electronic Science and Technology of China

About: University of Electronic Science and Technology of China is a education organization based out in Chengdu, China. It is known for research contribution in the topics: Computer science & Antenna (radio). The organization has 50594 authors who have published 58502 publications receiving 711188 citations. The organization is also known as: UESTC.

Cascaded Channel Estimation for Large Intelligent Metasurface Assisted Massive MIMO

Abstract: In this letter, we consider the problem of channel estimation for large intelligent metasurface (LIM) assisted massive multiple-input multiple-output (MIMO) systems. The main challenge of this problem is that the LIM integrated with a large number of low-cost metamaterial antennas can only passively reflect the incident signal by a certain phase shift, and does not have any signal processing capability. To deal with this, we introduce a general framework for the estimation of the transmitter-LIM and LIM-receiver cascaded channel, and propose a two-stage algorithm that includes a sparse matrix factorization stage and a matrix completion stage. Simulation results illustrate that the proposed method can achieve accurate channel estimation for LIM-assisted massive MIMO systems.

The effect of ambient humidity on the electrical properties of graphene oxide films

Abstract: We investigate the effect of water adsorption on the electrical properties of graphene oxide (GO) films using the direct current (DC) measurement and alternating current (AC) complex impedance spectroscopy. GO suspension synthesized by a modified Hummer's method is deposited on Au interdigitated electrodes. The strong electrical interaction of water molecules with GO films was observed through electrical characterizations. The DC measurement results show that the electrical properties of GO films are humidity- and applied voltage amplitude-dependent. The AC complex impedance spectroscopy method is used to analyze the mechanism of electrical interaction between water molecules and GO films in detail. At low humidity, GO films exhibit poor conductivity and can be seen as an insulator. However, at high humidity, the conductivity of GO films increases due to the enhancement of ion conduction. Our systematic research on this effect provides the fundamental supports for the development of graphene devices originating from solution-processed graphene oxide.

Novel series of ultra-low loss microwave dielectric ceramics: Li2Mg3BO6 (B = Ti, Sn, Zr)

Abstract: Using a conventional solid-state reaction Li2Mg3BO6 (B = Ti, Sn, Zr) ceramics were prepared and their microwave dielectric properties were investigated. The analysis revealed that cubic Li2Mg3BO6 (B = Ti, Sn, Zr) ceramics with a rock salt structure could be obtained in their respective sintering temperature range. Three promising ceramics Li2Mg3TiO6, Li2Mg3SnO6 and Li2Mg3ZrO6 sintered at 1280 °C, 1360 °C and 1380 °C possessed out-bound microwave dielectric properties: ϵr = 15.2, 8.8 and 12.6, Q × f = 152,000 GHz (at 8.3 GHz), 123,000 GHz (at 10.7 GHz) and 86,000 GHz (at 9.3 GHz), and τf = −39 ppm/°C, −32 ppm/°C and −36 ppm/°C, respectively.

A Novel Electronic Beam Steering Technique in Time Modulated Antenna Array

Abstract: In this paper, a novel technique for electronic beam steering in time modulated linear array (TMLA) is proposed. The beam steering technique is realized at the flrst sideband by controlling the switch-on time sequences of each element in the TMLA without using phase shifters. The difierential evolution (DE) algorithm is employed to improve the gain and suppress the sidelobe levels (SLLs) at both the center frequency and the flrst sideband, simultaneously. An S-band 8-element double-layered printed dipole linear array was used to verify the technique experimentally. Measured results are compared with numerical data, and good agreement is reported. Moreover, some simulation results on the binary phase shift keying (BPSK) modulated signals arriving from difierent directions received by the proposed approach are presented, which validates the application of the proposed beam steering technique.