Ming-Hsueh Chuang

Design and applications of radio-over-fiber schemes to indoor wireless coverage and highspeed rails

A low-cost radio-over-fiber (RoF) based integrated transmission of long term evolution (LTE) and worldwide interoperability for microwave access (WiMAX) signals is proposed to solve the shadowing effect of building envelopes and the complexity of transmitting system in wireless access network services. This scheme is also applied to solve the problems of required fast handover and poor signal penetration in tunnels for high-speed rail mobile connections. We design and demonstrate experimentally a multi-service WiMAX/LTE RoF system that can extend the indoor signal coverage, with an emphasis on the power conversion efficiency and optoelectronic component selections. The designed RoF transceivers and switches are being deployed in both the campus buildings and the tunnels of Taiwan High-Speed Rail system to allow mobile connections.

Design and implementation of subchannelization scheduler in IEEE 802.16 broadband wireless access systems

Abstract In this paper we propose a method of using a heuristic Genetic Algorithm (GA) to solve the Fast Fourier Transform subchannelization scheduling (FFTSS) problem in IEEE 802.16 broadband wireless access systems. In such a multi‐user transmission system with quality of service (QoS) requirements, data from different users should be quickly scheduled and transmitted within the shortest transmission time period. In this paper, we propose a GA‐based scheduler that will search the best configurations of the uplink and/or downlink sub‐frames in order to obtain the optimal system throughput as well as quality of services. Due to the slow convergence of conventional GAs, we design a novel hardware architecture to accelerate the processing speed of GA which is used for scheduling the Down Link (DL) sub‐frames. We then describe the procedure of using Field‐Programmable Gate‐Array (FPGA) to implement the designed hardware to verify the convergence of the algorithm. With this hardware implementation, the proposed method indeed helps us to construct a fast optimization tool to be applied in broadband wireless communication systems.

Shared-seeding scheme for integrated services in WDM-PON access networks

A shared seeding WDM-PON system is proposed to provide multiple integrated services with reduced Rayleigh scattering effects on upstream transmission. The shared seeding source is also used to provide additional services with low power penalty.

Demonstration of bidirectional wired and wireless services in integrated optical and wireless system carried by single wavelength lightwave

We propose and demonstrate a novel RSOA-based WDM-PON architecture for converging Gb/s-NZR and 16QAM-OFDM ROF signals by employing wavelength reuse techniques. The bidirectional wired and wireless services can successfully be delivered over 25 km fiber by using one single lightwave.

RoF-based indoor WiMAX transmission system

In this paper, we use the radio-over-fiber (RoF) technology to extend indoor WiMAX coverage. The RoF-based indoor WiMAX experimental platform can be divided into two kinds of basic architectures: point-to-point and point-to-multipoint. We discuss various setups and optimize the systems to ensure the transmission distance up to 15 meter and sustain 64-QAM modulation.

ANALYSIS OF SYSTEM PERFORMANCE FOR AN OPTICAL CDMA SYSTEM IMPLEMENTED WITH SYNCHRONOUS RECEIVER

Abstract In this paper, we study and analyze the system performance of an optical code‐division multiplex access (CDMA) system implemented with synchronous receiver. In the traditional optical CDMA access system, optical signals emitted from users are transmitted at the same power level. When these signals arrive at the receiver terminal, due to different distances traveled for each signal from the transmitter to the receiver, they will be at different power levels. In this paper we propose a mechanism to estimate first the distance between a transmitter and a receiver and then from this distance information to estimate its associated time delay so as to shift the signal time frame structure and adjust its transmitting power level so that a synchronous receiving system is generated. Using the VPItransmissionMaker software the system performance of the proposed system is simulated, and the results show that the proposed synchronous receiving system gives better performance than a traditional synchronous transmitting system.

Inter-cell Interference Management in DL/UL PHY Control for IEEE802.16m

Some interference management measures in the PHY Control to reduce possible interferences in the transmission between an MS and BSs are proposed. The design and assignment procedures to generate pilots to have lower interference levels are introduced and discussed. Based on the design process each pilot is accordingly assigned an interference weight with respect to a basic pilot and with this design in the system simulation by utilizing the generated pilots to IEEE 802.16m system it reveals that the system performance has 7.5 dB and 23 dB advantages in the interference levels for 7 BSs and 19 BSs respectively comparing with the conventional pilot design that assigns the pilots with the same interference weight for all BSs.

A Hybrid System with Petri Net and Fuzzy Theory

In this paper, we issue a hybrid system, which is integrated with the fuzzy system and Petri net models. We exploit the characteristics, imprecise or ambiguous information, of fuzzy theory to map the algorithm of crisp inputs and outputs, furthermore, model problems, product a nonlinear function, and final predict the next state transition of Petri net graphs. In order to quickly and precisely predict the result state, we use the Center of Area (COA) defuzzification method to infer the state transition for this hybrid system. Finally, we issue an example of washed-machine to illustrate this proposed hybrid system.

Performance enhancement of radio-over-fiber system by optical injection locking of a directly modulated semiconductor laser

We investigated experimentally the effects of optical injection locking on the performance of a directly modulated semiconductor distributed feedback laser, aiming for radio-over-fiber (RoF) applications. The resonance frequency and noise level are measured at various frequency detuning and external injection ratios. Under optical injection locking with a -2.9dB injection ratio and -12.5GHz detuning, the resonance frequency improved 2.81 times and noise level at the peak reduced by 3.5dB compared to a free running laser. We also achieved 5dB dynamic range enhancement with the same injection conditions. A resonance frequency improvement of 4.2 times was achieved with increased detuning. Performances of a ROF system were evaluated at RF frequencies of 2, 2.5 and 3GHz using a 64-QAM signal. From the error vector magnitude measurements, the optical injection locking can both enhance the linearity and reduce the noise for direct modulation, and thus extending the dynamic range of input RF signals.

An uplink pilot design for IEEE802.16m

This paper provides some design considerations of pilot structure for 1-antenna and 2-antenna IEEE802.16m. Space-Zone (SP-Zone) and Mobility-Zone (MB-Zone) concepts are introduced to use different numbers of subcarriers and symbols between pilots according to the radio environment and mobile speed to improve the system performance comparing with the conventional fixed number of subcarriers and symbols between pilots.