Fenq-Lin Jenq

An AC LED smart lighting system with white light FSO communication

Due to the AC LED applications are simpler and higher conversion efficiency than DC LED, the white AC LED is the better choose for general illumination in future. And LED can be applied for data transmission. In this paper, we propose a AC LED smart lighting system of visible light FSO transmission with AC LED as the transmitter and a photo sensor as the receiver. The timing of data transmitting is synchronous with the AC power source, and transmitting optical signal would keep in a level.

An AC LED Smart Lighting System with Visible Light Time-Division Multiplexing Free Space Optical Communication

Owing to AC LED can be driven directly without any AC to DC converter, the volume and the cost of AC LED can be reduced. Avoiding the power conversion loss, AC LED can have lower energy consumption and higher luminous efficiency than DC LED does. Because of high brightness, low power consumption and long lifetime, LED has been used as a lighting device and is expected to replace the high power-consuming incandescent and fluorescent lamps in the 21th century, in consequence the white light AC LED is a better choice for general illumination in the future. In this study, a white light AC LED smart lighting system equipped with visible light time-division multiplexing optical communication for free space is proposed. In the system, the timing to transmit data is synchronized with the period of the AC power on the wall, in order to keep the transmitted optical signal in an enough level. As a result, the time-division multiplexing optical communication by AC LED lighting is achieved.

A Novel Microwave Microstrip Surface Acoustic Wave Filter with Gigahertz Band Low-Loss Wide Bandwidth for Broad Spectrum Communication System

A novel GHz-band low-loss wide bandwidth microwave microstrip, surface acoustic wave (SAW) filter used for the spread spectrum communication system has been designed and fabricated. The 16-µm-input/output-interdigital-transducer (IDT) LiNbO3 61.00-MHz-SAW filter with microwave square open-loop resonators has an insertion loss of 3.987 dB. This device is also a 1 GHz microwave microstrip SAW filter with four coupled microstrip square open-loop resonators and two planar interdigital capacitors with S21 and S11, having bandwidths of -2.962 dB and -25.497 dB, respectively, and 800 MHz. It is speculated that the characteristics of these low-loss wide bandwidth (BW=80%) microstrip SAW filters are influenced by the interaction between electromagnetic wave and piezoelectric SAW. To confirm this speculation, devices with the same design have been fabricated on 128°-rotated YX-cut LiNbO3,GaAs S-I and 9000 A SiO2/Si substrates. Significant variations of performance are observed among these devices.

A path switching scheme for SCTP based on round trip delays

Due to the rapid development of network applications, today the Internet plays an important role in our everyday life. Users hope that the network is always speedy enough to help them access the Internet without any delay. But the real situation is far from the ideal case. In the future, network researchers will continuously improve the network speed, and try to develop networks that are robust, without any crashes or packet loss. In this paper, we propose an aggressive path switching scheme for SCTP. Before data transmission, the scheme selects the fastest path as the primary path to transmit packets. When the path fails or transmission quality is poor, this scheme evaluates alternate paths, and selects the one with the best quality as the new primary path to substitute for the original one. After that, packets are delivered through the new path. Several factors are considered in the evaluation, including bandwidth, encryption/decryption, size of the congestion window, retransmission policy, routing policy, etc.

A smart lighting system with white LED FSO communication

Due to the reliability and high efficiency, the white LED sources are widely used for general illumination, and they can also be applied for data transmission. In this paper, we propose a smart lighting system of visible light FSO transmission with white LEDs as the transmitter and a photo sensor as the receiver. The advantage is that the brightness of LEDs keeps consistent regardless of whether the transmission carries or not.

Design of a compact dual-mode ring resonator bandpass filter with harmonic suppression

Abstract An approach to suppress the harmonic responses in a dual-mode circular ring resonator bandpass filter is presented. Feed lines with one-sided coupling arms are suitably relocated around the ring resonator to introduce phase interference between two degenerate modes for simultaneously suppressing the second and third harmonics. Three open loop resonators at the rim of the ring are adopted to further suppress the second harmonic. By fabricating on a FR4 glass-epoxy base, this approach is demonstrated to have effectiveness in broadening the filters rejection band in both simulations and measurements without affecting the fundamental response or increasing the device size.

Role of Annealing in Constant Period of Voltage Stress on the Burn-in Effect Suppression of InGaP/GaAs Heterojunction Bipolar Transistors

Rapid thermal annealing (RTA) is proved to be more efficient in dissociating hydrogen complexes than using a constant period of voltage stress (CPVS). Without waiting for the bond breaking of complexes by minority carrier injection, RTA favors the critical base–emitter voltage (VBE) responsible for the occurrence of burn-in (BI) from 1.75 to 1.4 V and thus assists CPVS in reducing VBE by about 25% used in BI suppression. Besides eliminating the BI, the sample first prepared by RTA and followed by CPVS has larger base and collector current densities at VBE>1.1 V and reaches 6 times those at VBE>1.3 V compared with the sample only using by CPVS.