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A Linear Precoding Technique for OFDM Systems with Cyclic Delay Diversity
( Bing Hui ),( Kyunghi Chang ) 한국인터넷정보학회 2008 KSII Transactions on Internet and Information Syst Vol.2 No.5
Cyclic delay diversity (CDD) is considered a simple approach to exploit the frequency diversity, to improve the system performance in orthogonal frequency division multiplexing (OFDM) systems. Also, the linear precoding technique can significantly improve the performance of communication systems by exploiting the channel state information (CSI). In order to achieve enhanced performance, we propose applying linear precoding to the conventional CDD-OFDM transmit diversity schemes over Rayleigh fading channels. The proposed scheme works effectively with the accurate CSI in time-division-duplex (TDD) OFDM systems with CDD, where the reciprocity is assumed instead of channel state feedback. For a BER of 10<sup>-4</sup> and the mobility of 3 km/h, simulation results show that a gain of 6 dB is achieved by the proposed scheme over both flat fading and Pedestrian A (Ped A) channels, compared to the conventional CDD-OFDM system. On the other hand, for a mobility of 120 km/h, a gain of 2.7 dB and 3.8 dB is achieved in flat fading and Vehicular A (Veh A) channels, respectively.
Structure of PVA/gelatin hydrogel beads and adsorption mechanism for advanced Pb(II) removal
Bing Hui,Yi Zhang,Lin Ye 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.21 No.1
Poly(vinyl alcohol)(PVA)/gelatin hydrogel beads were prepared for Pb2+ removal. The loose network structure formed at high dosage of gelatin resulted in increasing permeability and Pb2+ adsorption capacity. High content of Pb2+ was adsorbed on the surface of hydrogel, which dense structure could hinder Pb2+ to internal diffusion. The Pb2+ adsorption was rapid and spontaneous, and favorable at high temperature and Pb2+ concentration; Langmuir isotherm fits well with the experimental data, indicating homogeneous nature of monolayer adsorption of Pb2+; the adsorption process belonged to the secondorder kinetic model, indicating chemical adsorption with ion-exchange mechanism. Good reusability of the hydrogel was achieved.
Bing Liu,Hai-Qiang Li,Hao-Bing Li,Jian Liu,Yi-Zhong Yang,Yan-Hui Lu,Abid Ali 한국응용곤충학회 2015 Journal of Asia-Pacific Entomology Vol.18 No.2
Lygus pratensis distributes worldwide and is one of the common insect pests on cotton in Xinjiang Uygur Autonomous Region, the largest cotton growing region of China. This study assessed the effects of six constant temperatures (10, 15, 20, 25, 30 and 35 °C) at 60% relative humidity (RH) on egg and nymphal development of L. pratensis. Eggs failed to hatch and the newly-hatched nymphs could not normally develop at 10 °C. The developmental duration of egg and nymph decreased as temperature increased from 15 to 30 except 35 °C for egg. Based on the linear model, the lower developmental threshold and effective accumulated temperature were 10.68 °C and 150.2 DD for egg, and 12.08 °C and 208.3 DD for nymph, respectively. Among three non-linear models (Briere-1, Logan-6 and Lactin), Logan-6 provided the most accurate estimate for the mean optimum and lethal maximum temperatures (33.6 and 40.9 °C for egg, and 34.0 and 37.4 °C for nymphs). The interactive effects of three RH levels (45, 60 and 75%) and two temperatures (25 and 35 °C) on the immature developmental stages were tested. Temperature, RH and their interaction showed significant effects on egg and nymphal development. High relative humidity (75% RH) shortened the developmental duration of egg at 25 °C and nymph at 25 and 35 °C,whereas no significant difference was found for egg duration between different RH levels at 35 °C. The present study is useful for further predicting the phenology of L. pratensis and developing forecast and management strategies for this emerging mirid bug in China.
NOMA Transceiver Design for Highway Transportation in Mobile Hotspot Networks
Bing Hui,김준형,최성우,정희상,김일규,이훈 한국전자통신연구원 2016 ETRI Journal Vol.38 No.6
The mobile hotspot network (MHN), which is capable of providing a data rate of gigabits per second at high speed, is considered a potential use case of the future enhanced mobile broadband for 5G. Because a unidirectional network deployment has been considered for an MHN, non-orthogonal multiple access (NOMA) can be employed to improve the system performance. For a practical implementation of NOMA under an MHN highway scenario where multiple pieces of MHN terminal equipment are served through the same beam simultaneously, a NOMA transceiver is proposed in this paper. For the NOMA transmitter, Gray-coded QAM constellation mapping is extended to arbitrary modulation order q. For the NOMA receiver, successive interference cancellation (SIC) is no longer necessary, and instead, a parallel demodulation is proposed. The numerical and simulation results suggest that the proposed NOMA transceiver outperforms the conventional NOMA SIC receiver and can be flexibly used for an MHN highway scenario.
Bing Hui,Lin Ye 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.35 No.-
Polyvinyl alcohol-g-acrylic acid-2-acrylamido-2-methyl-1-propanesulfonic acid hydrogel (PVA-g-AA-AMPS) with varying AMPS/AA molar ratio was synthesized. The shear storage modulus and effectivenetwork density of the hydrogel increased with AMPS dosage, and more uniform and dense porousnetwork structure formed. Pb2+ adsorption capacity of the hydrogel increased with AMPS/AA molar ratio,while Langmuir isotherm fitted well with the experimental data, indicating homogeneous nature ofmonolayer adsorption of Pb2+. The adsorption was rapid and spontaneous, favorable at hightemperature, and belonged to the second-order kinetic model, indicating chemical adsorption withion-exchange mechanism. Good reusability of the hydrogel was achieved.