Yih-Guang Jan

Measurement of RF PCB Dielectric Properties and Losses

This paper presents the calculations of transmission line loss factor by extracting from the Q-factor measurement of the quarterwavelength open stub resonators over the designed frequency and other resonant frequencies. A comparison of the loss factor of the design frequency with other resonant frequencies of each of the stub’s quarter-wave resonances is provided in this paper. The radiation and discontinuity losses are undesirably included in the unloaded Q-factor measurement and it shows that the unloaded Q-factor is not repeatable at different designed frequency. The implementation of the loss factor measurement by quarter-wavelength open stub resonators is becoming more and more important to be considered with the increase of using the electronic circuits operating at high frequencies. † This author is also with Department of Electronic Engineering, Tam Kang University, 151 Ying-chuan Road, Tamsui, Taipei County, Taiwan 25137, R.O.C.

The Measurement and Analysis of WiMAX Base Station Signal Coverage

This paper presents the fleld trial measurement data of WiMAX base station; it includes the system coverage, signal strength and available transmission rate. Data consisting of real time images, VoIP internet telephone are transmitted through Skype software by using WiMAX, HSDPA (3.5G) and EDGE (2G) transmission techniques, and these data are connected to centrally equipped wireless monitoring servers to perform data monitoring and analysis. Finally, we make comparisons, analysis and discussions of these three transmission techniques from the measured and characterized data.

Performance Analysis with Coordination Among Base Stations for Next Generation Communication System

Next generation communication system, such as Long Term Evolution Advanced (LTE-A), has the advantages of high transmission rate, wide bandwidth and better bandwidth utilization in high mobility environments. However, in such a kind of system when users are distributed sparsely in the base station coverage range the spectrum e-ciency becomes worse. The emergence of new technologies such as the coordination among based stations makes the utilization of system bandwidth more e-cient. The technology of coordination among base stations has other merits such as reducing noise interference, increasing receiving diversity, improving the system receiving gain, etc. In this paper, the system spectrum utilization and its associated e-ciency will be investigated when the scheme of coordination among base stations is implemented.

Using Genetic Algorithm with frequency hopping in device to device communication (D2DC) interference mitigation

Device-to-device communication (D2DC) is an important and challenge technique in the next generation of wireless communication that it can effectively reduce the load of base stations and simultaneously allows user equipment (UE) to proceed in direct communications. In D2DC, devices are very close among themselves and therefore the resulting interferences maybe quite serious, it becomes an important issue of how to properly select a UE owner so that when this UE owner searches for its associated communicating UEs in its service range they will suffer the least interference effect. In this paper, as UEs are distributed and clusters of UEs are formed in the D2D communication area; we propose to use K-Means to locating a UE around the cluster center as the UE Owner of the cluster. With this formation of UE clusters and UE owners they still have the chance to incur interferences among UE clusters due to they may be possibly use the same frequency band in their communications. Frequency hopping technique is then considered in this paper to further reduce the co-channel interference. In this paper it proposes to use Genetic Algorithm (GA) with frequency hopping technique to optimally select the number of frequency channels required in the system and then allocate these frequency channels to the UE clusters for their D2D communications. Simulations have been performed in a D2DC system with the proposed GA algorithm to reveal the effectiveness of the designed algorithm in the allocation of frequency channels to the clusters with minimum interference effect.

Using hopping technique for interference mitigation in Modulated Scattering Array Antenna system

In modulated scattering antenna array (MSAA) system it has at the receiver side encountered low levels of scattering signals [1,2] and interferences in addition to the desired signal. In this paper, we propose to utilize the frequency hopping scheme to improve the performance of scattering signals under the influence of narrow band strong interferences. From the numerical results, it concludes that with larger hopping range it improves the ability of anti-interference effects.

Using LDPC coding and AMC to mitigate received power imbalance in carrier aggregation communication system

When a carrier aggregation communication system suffers from receiving power imbalance (RPI) in its antenna array due to design flaw, operators negligence etc. the system performance may be degraded to an unacceptable level. Specifically in this paper a carrier aggregation communication system with two carrier links while one link suffers RPI is considered, various modulation techniques, such as QPSK, 16 QAM and 64 QAM and/or coding schemes, Convolution Code (CC) and Low Density Parity Check Code (LDPC) are implemented in the system performance simulation to investigate the system behavior when it has the design request to maintain the same system performance in each link when the RPI has values of 7 or 10dB.

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.

Applying Genetic Algorithms to the Data Traffic Scheduling and Performance Analysis of a Long-Term Evolution System

In this study it develops a superior transmission resource allocation method by using genetic algorithm. The convergence properties of genetic algorithm are employed to increase the transmission resource use efficiency of a base (station) to allow users to access wider bandwidth and to improve the system throughput and packet service rate. In this paper, it also studies the genetic algorithm convergent phenomena. The calculated system convergent time is significantly less than that of a long term evolution (LTE) frame duration. Finally, the system performances with and without implementing the genetic algorithm in resource allocations are simulated; their performances are compared to study the effectiveness of using the genetic algorithm in resource allocation.

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.