Browsing by Author "Hsiao, Wei-Han"

Now showing 1 - 12 of 12

A Novel 5G TDD Cellular System Proposal based on Multipath Division Multiple Access
(2017-01-01)
Hsiao, Wei-Han
;
Huang, Chia-Chi
;
資訊工程學系
;
電機工程學系
;
Department of Computer Science
Evolving from the 3G and the 4G communication systems, the 5G system demands both high system capacity and high data rate. A novel time division duplexing (TDD) cellular system based on multipath division multiple access (MDMA) with massive antennas in millimeter wave band is proposed in this paper. The system is built on multipath division multiple access which is a method to use massive antennas at BS along with the Rake receiver and the Pre-Rake transmitter to achieve a processing gain for suppressing multiple access interference. The system concept is demonstrated by computer simulations. In addition, the associated transceiver architecture and a TDD time slot structure are presented for practical system concerns. Moreover, it is shown through analysis that the total average data throughput equals 3.8 Gbps and the system can achieve a bandwidth efficiency of 19 bps/Hz/cell on 200 MHz transmission bandwidth.
Analysis and simulation of MDMA-A spectrum efficient non-orthogonal multiple access scheme for 5G communication
(2017-12-01)
Hsiao, Wei-Han
;
Huang, Chia-Chi
;
資訊工程學系
;
電機工程學系
;
Department of Computer Science
In this paper, an analysis and simulation approach is used to verify the performance of a recently proposed non-orthogonal multiple access scheme called multipath division multiple access (MDMA). The spatial multipath channel (SMC), which is the distinct feature for each user, is introduced to model the matrix channel of each user, taking into account the multipath structure and massive antennas. The signal and interference powers are then derived. Thus, the corresponding bit error probability can be approximated in a closed form. Moreover, computer simulation results are shown to be consistent with the analysis results. Most importantly, it is revealed that theMDMAsystem can achieve the superior cellular spectrum efficiency of 25 bps/Hz/cell which fulfills the 5G cellular system requirement. (c) 2017 Elsevier B.V. All rights reserved.
Case study and performance evaluation of MDMA-A non-orthogonal multiple access scheme for 5G cellular systems
(2018-08-01)
Hsiao, Wei-Han
;
Shih, Yung-Wen
;
Huang, Chia-Chi
;
電機工程學系
;
Department of Electrical and Computer Engineering
Multipath division multiple access (MDMA) has recently been proposed as a non-orthogonal multiple access scheme which exploits multipath domain to separate its users [1]. It is claimed that both the system capacity and total data throughput can be enhanced to a large amount. Yet, it is at its early stage of developments and it needs to be further investigated and clarified for its real use. In this paper, the feasibility and realizability of the MDMA cellular system are demonstrated by computer simulation. The receiver operation is also described in detail. Besides, the system performance is compared with those claimed in the original paper [1]. In addition, practical considerations on implementing the MDMA cellular system are discussed as well. With considerable amount of channel estimation error, it is shown that the system can still achieve 16 bps/Hz/cell with 300 BS antennas in cellular spectrum efficiency, which is an order of magnitude larger than the currently used first-generation to fourth-generation multiple access schemes. Thus, the MDMA can be considered as an implementable and spectrum efficient non-orthogonal multiple access scheme for future 5G systems.
Case Study and Performance Evaluation of MDMA-A Non-orthogonal Multiple Access Scheme for 5G Cellular Systems (vol 23, pg 1035, 2018)
(2018-08-01)
Hsiao, Wei-Han
;
Shih, Yung-Wen
;
Huang, Chia-Chi
;
電機工程學系
;
Department of Electrical and Computer Engineering
Design of Downlink Synchronization for Millimeter Wave Cellular System Based on Multipath Division Multiple Access
(2020-09-01)
Chiu, Kang-Lun
;
Shen, Pai-Hsiang
;
Lin, Bing-Ru
;
Hsiao, Wei-Han
;
Jou, Shyh-Jye Jerry
This work focuses on the design of downlink receiver for future generation cellular systems. In the multipath division multiple access (MDMA) system, the initial synchronization process includes timing and carrier frequency synchronization as well as home cell search. For the proposed system, the user data is transmitted in time domain and the cell search is based on control signals transmitted in frequency domain simultaneously. Firstly, this paper presents a novel architecture for the joint detection and estimation of both the coarse symbol boundary and the fractional carrier frequency offset based on cyclic prefix in time domain. Secondly, a robust integer carrier frequency offset detection is performed with the primary control tone in frequency domain. Moreover, the position of the secondary control tones is used to obtain the cell ID. Finally, the preamble sequence carried by the secondary control tones is used to detect frame header through differential detection. The simulation results show the proposed synchronization algorithms can achieve detection failure rate less than 1% and the normalized residual carrier frequency offset is less than 5% under the interference of user data. Furthermore, a hardware design targeted at 200 Mbps per-user data rate is realized with memory arbiter to share memory.
Growth of Cu nanobelt and Ag belt-like materials by surfactant-assisted galvanic reductions
(2007-05-08)
Huang, Ting-Kai
;
Cheng, Tzu-Hou
;
Yen, Ming-Yu
;
Hsiao, Wei-Han
;
Wang, Lung-Shen
We demonstrate the syntheses of single crystalline Cu nanobelt and Ag belt-like materials via CTAC-assisted (CTAC, cetyltrimethylammonium chloride) galvanic reductions. The single crystalline face-centered cubic phase Cu nanobelt was prepared by reacting CuCl2(aq) with Al(s) in an aqueous solution of CTAC and HNO3. The Cu nanobelt exhibited a high-quality ribbon-like nanostructure with a thickness less than 15 nm, a width of 30-150 nm, and a length up to 10 mu m. The belt-like Ag, with a thickness less than 10 nm, a width of 30-100 nm, a length up to 5 mu m, and a novel single crystalline 4H structure, was prepared by reacting AgNO3(aq) and Cu(s) in an aqueous solution of CTAC.
Majorana zero modes in spintronics devices
(2017-01-24)
Wu, Chien-Te
;
Anderson, Brandon M.
;
Hsiao, Wei-Han
;
Levin, K.
;
電子物理學系
We show that topological phases should be realizable in readily available and well-studied heterostructures. In particular we identify a new class of topological materials which are well known in spintronics: helical ferromagnet-superconducting junctions. We note that almost all previous work on topological heterostructures has focused on creating Majorana modes at the proximity interface in effectively two-dimensional or one-dimensional systems. The particular heterostructures we address exhibit finite-range proximity effects leading to nodal superconductors with Majorana modes localized well away from this interface. To show this, we implement a Bogoliubov-de Gennes (BdG) proximity numerical scheme, which importantly involves two finite dimensions in a three-dimensional junction. Incorporating this level of numerical complexity serves to distinguish ours from alternative numerical BdG approaches which are limited by generally assuming translational invariance or periodic boundary conditions along multiple directions. With this access to the edges, we are then able to illustrate in a concrete fashion the wave functions of Majorana zero modes and, moreover, address finite-size effects. In the process we establish consistency with a simple analytical model.
Multipath Division Multiple Access for 5G Cellular System based on Massive Antennas in Millimeter Wave Band
(2016)
Hsiao, Wei-Han
;
Huang, Chia-Chi
;
電機工程學系
;
Department of Electrical and Computer Engineering
Mobile communications toward the fifth generation (5G) have been popularly discussed and investigated worldwide in academia and industry. 5G, as an evolution from the previous generations, demands both high system capacity and high data rate. A novel multiple access scheme based on millimeter wave transmission and massive antennas at a base station (BS), named multipath division multiple access (MDMA), is proposed in this paper to be a future 5G possible solution. MDMA is defined here as a method to use massive antennas at BS to achieve a processing gain to suppress multiple access interference (MAI) in cellular mobile radio system. The processing gain is obtained by implementing RAKE receivers at BS. The system concept is also demonstrated by computer simulations. Moreover, it has been shown through simple but crucial analysis that the system capacity and the aggregated data throughput could be boosted up to a considerable level.
Quantum phase transitions in proximitized Josephson junctions
(2018-08-13)
Wu, Chien-Te
;
Setiawan, F.
;
Anderson, Brandon M.
;
Hsiao, Wei-Han
;
Levin, K.
We study fermion-parity-changing quantum phase transitions (QPTs) in platform Josephson junctions. These QPTs, associated with zero-energy bound states, are rather widely observed experimentally. They emerge from numerical calculations frequently without detailed microscopic insight. Importantly, they may incorrectly lend support to claims for the observations of Majorana zero modes. In this paper, we present a fully consistent solution of the Bogoliubov-de Gennes equations for a multicomponent Josephson junction. This provides insights into the origin of the QPTs. It also makes it possible to assess the standard self-energy approximations, which are widely used to understand proximity coupling in topological systems. The junctions we consider are complex and chosen to mirror experiments. Our full proximity calculations associate the mechanism behind the QPT as deriving from a spatially extended, proximity-induced magnetic "defect." This defect arises because of the insulating region, which effects a local reorganization of the bulk magnetization in the proximitized superconductor. Our results suggest more generally that QPTs in Josephson junctions generally do not require the existence of spin-orbit coupling and should not be confused with, nor are they indicators of, Majorana physics.
Surface-Enhanced Raman Scattering Imaging of a Single Molecule on Urchin-like Silver Nanowires
(2011-09-01)
Hsiao, Wei-Han
;
Chen, Hsin-Yu
;
Yang, Yu-Cheng
;
Chen, Yu-Liang
;
Lee, Chi-Young
Urchin-like silver nanowires are prepared by reacting AgNO(3)(aq) with copper metal in the presence of cetyltrimethylammonium chloride and HNO(3)(aq) on a screen-printed carbon electrode at room temperature. The diameters of the nanowires are about 100 nm, and their lengths are up to 10 mu m. Using Raman spectroscopy, the detection limit of Rhodamine 6G (R6G) on the urchin-like silver nanowire substrate can be as low as 10(-16) M, while the analytical enhancement factor is about 10(13). Raman mapping images confirm that a single R6G molecule on the substrate can be detected.
System Capacity and Convergence Rate Evaluation for Downlink Power Control in 5G MDMA Cellular Systems
(2018-01-01)
Hsiao, Wei-Han
;
Su, Jing-Jing
;
Tang, Zhi-Wen
;
Yin, Jia-Le
;
Huang, Chia-Chi
Several downlink power control (PC) algorithms are investigated in this paper for the fifth generation MDMA based cellular system. Among them, the closed-loop PC schemes are studied, which are useful to reduce the co-channel interference and increase the system capacity. Two kinds of iterative methods are commonly discussed. One is the SIR based approach, and the other is the eigenvalue based approach. Some representative PC algorithms are evaluated in terms of different performance metrics. In addition, an enhanced PC method is proposed which combines the advantages of the previous methods. It is shown by computer simulations that the proposed method achieves both desirable capacity performance and convergence rate in a 5G multipath division multiple access cellular system. Thus, the proposed method is a feasible downlink power control solution for 5G cellular systems.
Urchin-like Ag Nanowires as Non-enzymatic Hydrogen Peroxide Sensor
(2012-04-01)
Hsiao, Wei-Han
;
Chen, Hsin-Yu
;
Cheng, Ta-Ming
;
Huang, Ting-Kai
;
Chen, Yu-Liang
Urchin-like Ag nanowires were prepared by reacting AgNO3(aq) with Cu metal in the presence of cetyltrimethylammonium chloride and HNO3(aq) on a screen printed carbon electrode at room temperature. The diameters of the nanowires were about 100 nm, while the lengths were up to 10 mu m. Cyclic voltammetric experiments using the Ag nanowires as the working electrode showed electrocatalytic H2O2 reduction. The electrode exhibited a high sensitivity of 4705 mu A mM(-3) me cm(-2) from 50 mu M to 10.35 rnM and a measurable detection limit of 10 mu M in amperometric detection. This is the first report on Ag NWs for non-enzymatic H2O2 sensing.