Browsing by Author "Tien, Po-Lung"

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A 10G QoS-enabled optical packet-switching system: Technology and experimentation
(2006-01-01)
Lee, Steven S. W.
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Yuang, Maria C.
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Tien, Po-Lung
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Lin, Yu-Min
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Shih, Julin
The paper presents the architecture and experimentation of a 10-Gb/s QoS-enabled almost-all-optical packet switching system (QOPS) for metro WDM networks. By applying cluster-based wavelength sharing and downsized single-staged optical buffers, QOPS is featured by its highly scalable and cost-effective design. In this paper, we first introduce the switch architecture, system operation, and the key techniques. We describe the in-band header/payload modulation and optical label swapping that is suitable for high-speed optical packet switching. We also present the design of the highly efficient Four-Wave Mixing wavelength converters for packet preemption. We then present an adaptive bifurcated routing (ABR) that directs same-connection packets to different switch clusters according to optimal bifurcation probabilities. Experimental and simulation results demonstrate that QOPS can achieve superior packet-loss performance, QoS differentiation, and minimize traffic blocking probability.
A 40-Gb/s OFDM PON System Based on 10-GHz EAM and 10-GHz Direct-Detection PIN
(2012-01-01)
Chen, Hsing-Yu
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Wei, Chia Chien
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Hsu, Dar-Zu
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Yuang, Maria C.
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Chen, Jyehong
This letter demonstrates a 40-Gb/s optical double-sideband (ODSB) orthogonal frequency-division multiplexing passive optical network (OFDM-PON) system using a cost-effective 10-GHz-bandwidth electroabsorption modulator (EAM). By employing a subcarrier-adaptive modulation format and pre-emphasis, we successfully achieve 20-km EAM-based single-mode-fiber (SMF) transmission.
A High-Performance OFDMA PON System Architecture and Medium Access Control
(2012-06-01)
Yuang, Maria C.
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Tien, Po-Lung
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Hsu, Dar-Zu
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Chen, Shing-Yu
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Wei, Chia-Chien
Orthogonal frequency-division multiplexing (OFDM) passive optical network (PON) has been considered to be a promising next-generation broadband wired access solution. However, based on the current tree-based architecture, existing OFDM PON systems face severe challenges when increasing the scalability and data-rate performance. In this paper, we propose a high-performance virtual-tree orthogonal frequency-division multiple access PON system (VTOPS). With the virtual-tree architecture and coupled with the use of inexpensive direct modulation, VTOPS features high reliability, scalability, spectrum efficiency, and cost effectiveness all at once. For governing the flexible/fair access and dynamic allocation of bandwidth, VTOPS incorporates a rate-based medium access control (MAC) scheme. The MAC scheme performs dynamic rate adjustment using a neural-fuzzy system. By adjusting the system parameters, the MAC scheme can achieve a wide range of delay and fairness performance under a variety of traffic patterns. Finally, we show both theoretical and experimental results to demonstrate that, by applying the power pre-emphasis algorithm and adaptive subchannel modulation, VTOPS achieves 40 Gb/s downlink and 40 Gb/s uplink transmissions, using low-cost 10 GHz directly modulated lasers.
A High-Performance Optical Access and Control System for Packet-Switched WDM Metro Ring Networks
(2008)
Yuang, Maria C.
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Chao, I-Fen
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Lin, Yu-Min
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Lo, Bird C.
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Tien, Po-Lung
In this paper, we present the access and control design of a High-Performance Optical Packet-Switched WDM Metro ring Network (HOPSMAN). HOPSMAN has been designed for networks and nodes to be unconstrained by the number of wavelengths. It includes a handful of nodes that are equipped with fast optical slot erasers making bandwidth reusable and achieving greater bandwidth efficiency. In essence, HOPSMAN incorporates a versatile Medium Access Control (MAC) scheme, which embodies efficient and fair bandwidth allocation in accordance with a quota being exerted probabilistically. The quota is analytically derived with the number of slot-eraser-nodes taken into account. The scheme also employs a new notion of credit to regulate flexible access of remaining bandwidth that is suitable for the metro environment with bursty traffic. With the MAC scheme, HOPSMAN is shown to achieve exceptional throughput, delay, and fairness performance under a wide range of traffic settings via simulation results.
A New Discrete-Time Multi-Constrained K-Winner-Take-All Recurrent Network and Its Application to Prioritized Scheduling
(2017-11-01)
Tien, Po-Lung
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交大名義發表
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National Chiao Tung University
In this paper, we propose a novel discrete-time recurrent neural network aiming to resolve a new class of multi-constrained K-winner-take-all (K-WTA) problems. By facilitating specially designed asymmetric neuron weights, the proposed model is capable of operating in a fully parallel manner, thereby allowing true digital implementation. This paper also provides theorems that delineate the theoretical upper bound of the convergence latency, which is merely O(K). Importantly, via simulations, the average convergence time is close to O(1) in most general cases. Moreover, as the multi-constrained K-WTA problem degenerates to a traditional single-constrained problem, the upper bound becomes exactly two parallel iterations, which significantly outperforms the existing K-WTA models. By associating the neurons and neuron weights with routing paths and path priorities, respectively, we then apply the model to a prioritized flow scheduler for the data center networks. Through extensive simulations, we demonstrate that the proposed scheduler converges to the equilibrium state within near-constant time for different scales of networks while achieving maximal throughput, quality-of-service priority differentiation, and minimum energy consumption, subject to the flow contention-free constraints.
A Novel Passive Optical Network Architecture Supporting Seamless Integration of RoF and OFDMA Signals
(2010-03-15)
Lin, Yu-Min
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Tien, Po-Lung
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Yuang, Maria C.
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Lee, Steven S. W.
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Chen, Jason (Jyehong)
In this letter, we propose a novel passive optical network (PON) architecture supporting radio-over-fiber signals and orthogonal frequency-division multiple access (OFDMA) PON signals. The architecture transports upstream multiple remote antenna's wireless signals using only one upstream wavelength. In addition, the windowed-orthogonal frequency-division-multiplexing technique is employed to mitigate interference during the integration process. Experimental results shows that 10-Gb/s OFDMA and three radio-frequency signals at 2.1 GHz are successfully transmitted over 20-km single-mode fiber in a 32-optical-network-unit PON.
A QoS Optical Packet Switching System: Architectural Design and Experimental Demonstration
(2010-05-01)
Yuang, Maria C.
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Lin, Yu-Min
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Shih, Ju-Lin
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Tien, Po-Lung
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Chen, Jason J.
Optical packet switching has been considered a prominent paradigm for future WDM networks to efficiently support a multitude of applications with diverse quality of service requirements. In this article we present the architectural design and experimental demonstration of a 10 Gb/s QoS optical packet switching system (QOPSS) for WDM networks. It embodies a set of many-to-one space switches, each of which handles the switching solely for a cluster of wavelengths. With the cluster-based optical switch design, QOPSS trades off limited statistical multiplexing gains for higher system scalability. By many-to-one, multiple packets that are carried by different internal wavelengths are scheduled to switch to the same output port but receive different delays afterward. QOPSS adopts downsized feed-forward optical buffers, yielding drastic reduction in packet loss probability in an economical manner. Significantly, through using four-wave-mixing wavelength converters at the output section, QOPSS permits optical packet preemption, thus achieving effectual QoS differentiation. The article presents both simulation and experimental testbed results to demonstrate the feasibility and superior packet loss/QoS performance of the system.
A Virtual-Tree OFDMA PON System Architecture
(2012)
Yuang, Maria
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Tien, Po-Lung
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Chen, Jyehong
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Shih, Ju-Lin
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Hsu, Dar-Zu
OFDM PON has been considered to be one of the most prominent next-generation broadband wired access solutions. However, based on the current tree-architecture, existing OFDM PON systems face severe challenges when increasing the scalability and data-rate performance. In this paper, we propose a novel virtual-tree architecture of an OFDMA PON system (VTOPS). Coupled with the use of inexpensive direct modulation, VTOPS simultaneously achieves high reliability, scalability, and spectrum efficiency (i.e., high data rate) in a cost-effective manner. Theoretical and experimental results demonstrate that, by applying the pre-emphasis algorithm and subchannel adaptive modulation, VTOPS achieves 40-Gb/s downlink and uplink transmissions using low-cost 10-GHz directly modulated lasers.
An Energy and Cost Efficient WDM/OFDMA PON System Architecture
(2013-01-01)
Yuang, Maria
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Tien, Po-Lung
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Chen, Jyehong
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資訊工程學系
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Department of Computer Science
In this paper, we propose an energy and cost efficient WDM/OFDMA PON system architecture, referred to as NEWOPS. Based on a two-tiered semi-tree topology, NEWOPS allows a large number of ONUs to be connected to OLT using only a handful of colorless transceivers. NEWOPS\' unique architecture not only facilitates high spectral efficiency and flexible sub-channel bandwidth allocation, but also enables the system to achieve high energy and cost efficiency. We conduct a theoretical study to identify and resolve a new data-rate performance issue due to the colorless and wavelength re-use design of the system. Experimental results show that when only 5-GHz bandwidth is allotted for each wavelength, NEWOPS successfully achieves symmetric 20-Gb/s downstream and upstream OFDM-16QAM transmissions via the same fiber trunk. As a demonstration of our system, we show how NEWOPS achieves energy efficiency that is two to twelve times higher than that of a typical tree-based WDM/OFDM PON when supporting 40 ONUs.
An Energy and Cost Efficient WDM/OFDMA PON System: Design and Demonstration
(2013-08-15)
Yuang, Maria C.
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Hsu, Dar-Zu
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Tien, Po-Lung
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Chen, Hsing-Yu
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Wei, Chia-Chien
In this paper, we propose an energy and cost efficient WDM/OFDMA PON system, referred to as NEWOPS. Based on a new two-tiered semi-tree architecture, NEWOPS allows a large number of ONUs to be connected to OLT using only a handful of colorless transceivers. Due to the architecture, NEWOPS not only facilitates high spectral efficiency and flexible sub-channel bandwidth allocation, but also reduces the Rayleigh backscattering (RB) problem and achieves high energy and cost efficiency. Experimental results demonstrate that, taking only 5-GHz bandwidth for each wavelength, NEWOPS successfully achieves 20-Gb/s downstream and 10-Gb/s upstream OFDM-xQAM transmissions via the same fiber trunk. We depict that, to support 40 ONUs for example, NEWOPS achieves energy efficiency that is three to six times higher than that of a typical 10-Gb/s WDM/OFDM PON.
Demonstration of a Novel PON System with Distributed Real-Time Bandwidth Allocation
(2009)
Yuang, Maria C.
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Lin, Shih-Hsuan
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Lee, Steven S. W.
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Shih, Julin
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Lin, Yu-Min
This paper demonstrates a novel distributed control PON system (DCPON). Equipped with a distributed adaptable DBA algorithm that enables real-time precise bandwidth allocation, DCPON achieves high utilization, fairness, low request/response time, and superior service differentiation. (C)2009 Optical Society of America
Design and demonstration of a colorless WDM-OFDMA PON system architecture achieving symmetric 20-Gb/s transmissions with residual interference compensation
(2013-09-09)
Chen, Hsing-Yu
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Yuang, Maria
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Tien, Po-Lung
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Hsu, Dar-Zu
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Wei, Chia-Chien
In this paper, we propose a two-tiered colorless WDM-OFDMA PON system architecture that draws strengths from each individual WDM and OFDM PON systems. Specifically, the two-tiered architecture enables a colorless transceiver to be shared by a group of ONUs, resulting in drastic reduction of the system cost. For achieving colorlessness via reusing downstream light sources, we discover the residual power of downstream signal unexpectedly springs back after transmissions, causing severe interference to the upstream signal, and thus limiting the data rate of the upstream signal. We devise a method of adopting a common dispersion compensation module at OLT to reduce the residual power over all wavelengths. Experimental results show that, with an improvement of upstream signal's SNR up to 10dB, the system successfully achieves 20-Gb/s bidirectional OFDM-signal transmissions on the same wavelength over a 20-km SMF. (C) 2013 Optical Society of America
Fault-Tolerance Enhanced Design and Analyses for Optical Pyramid Data Center Network (OPMDC)
(2016)
Yuang, Maria C.
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Yang, Jing-Chun
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Chen, Hsing-Yu
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Tien, Po-Lung
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資訊工程學系
This paper presents a fault-tolerance enhanced design and analyses for OPMDC[1]. Capacity-based analysis shows OPMDC accommodates 0.91-capacity under the worst-case single WSS-failure. Emulation analysis justifies that a 26dB-OSNR is retained under the worst-case three-WSS-failure scenario.
HOPSMAN: An experimental testbed system for a 10-Gb/s optical packet-switched WDM metro ring network
(2008-07-01)
Yuang, Maria C.
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Chao, I-Fen
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Lo, Bird C.
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Tien, Po-Lung
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Chen, Jason J.
For future WDM MANs, optical packet-switching has been considered to be a promising paradigm that efficiently supports a wide range of Internet-based applications having time-varying and high bandwidth demands and stringent delay requirements. This article presents the design of an experimental testbed system for a high-performance optical packet-switched WDM metro ring network, HOPSMAN. HOPSMAN boasts three crucial features. First, it has a scalable architecture in which the number of nodes is unconstrained by the number of wavelengths. Second, HOPSMAN nodes are equipped with high-speed photonic hardware components, including fast tunable receivers and optical slot erasers, capable of performing speedy optical packet-switching operations. Third, HOPSMAN incorporates a MAC scheme that embodies efficient and dynamic bandwidth allocation, resulting in exceptional delay-throughput performance. The article presents the key hardware components by highlighting the challenging issues we faced and the solutions we proposed for the testbed implementation. Finally, to demonstrate the feasibility of HOPSMAN, the article describes the experimental setup and presents the results obtained from running a commercially available remote media player application on the system.
Next-Generation OFDMA-Based Passive Optical Network Architecture Supporting Radio-Over-Fiber
(2010-08-01)
Lin, Yu-Min
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Tien, Po-Lung
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電機工程學系
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Department of Electrical and Computer Engineering
In this paper, we propose a novel architecture for next-generation orthogonal frequency division multiple access (OFDMA)-based passive optical networks (PON's), referred to as ROFPON. Besides carrying local broadband OFDMA data, ROFPON seamlessly supports radio-over-fiber (RoF) transports between the central office and multiple remote antennas at end users without using costly WDM lasers. We analytically and experimentally study the receiver sensitivity to OFDMA signals and the radio frequency (RF) signal's performance. By corroborating simulation results with experimental results, we discuss the determination of crucial system parameters, such as the optimal broadband-to-radio power ratio, and the exploitation of a notch filter for removing RF interference. Experimental results show that the integrated 10 Gb/s OFDMA and three 20 MHz RF signals are successfully transported both downstream and upstream over a 20 km single-mode-fiber PON. Finally, experimental results demonstrate that QPSK-encoded WiMAX-format RF signals are transmitted/relayed upstream with E-O-E conversion at each optical network unit (ONU), and received error-free at the optical line terminal after cascading 32 ONU's.
OPMDC: Architecture Design and Implementation of a New Optical Pyramid Data Center Network
(2015-05-15)
Yuang, Maria C.
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Tien, Po-Lung
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Chen, Hsing-Yu
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Ruan, Wei-Zhang
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Hsu, Tzu-Kai
In this paper, we propose a novel optical pyramid data center network architecture (OPMDC), achieving scalable and high bandwidth, low latency, and reduced power consumption and wiring complexity. Based on an incremental and modular design, a full-scale OPMDC is built on three types of WSS-based optical switching nodes in three tiers. These optical nodes are recursively interconnected according to a pyramid structure parameterized by the number of nodes (B) at the base. Such a pyramid-based topology facilitates horizontal mesh connections that are tailored to achieve flexible optical packet-based transport. To this aim, we design a wavelength scheduling algorithm, called most-contentious-first, augmented with source and destination relay and aggregation (SDRA) via the horizontal mesh connections in the source and destination pods. Simulation results show that employing SDRA results in a vast improvement of throughput from 42.5% to 87.9% at full load, at a cost of no more than two additional hops of latency. Further, we present our OPMDC (B = 7) prototype and provide performance assessment and the measurements of packet latency. Finally, experimental results show that after travelling the longest possible path with six optical nodes in OPMDC, the signal suffers no accumulated distortion and noise from the cascades of WSS and EDFA modules.
Optical coarse packet-switched IP-over-WDM network (OPSINET): Technologies and experiments
(2006-08-01)
Yuang, Maria C.
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Lee, Steven S. W.
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Tien, Po-Lung
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Lin, Yu-Min
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Shih, Julin
Optical Packet Switching (OPS) has been envisioned as a prominent future optical networking technology for data-centric IP over Wavelength Division Multiplexing (WDM) networks, or optical Internet. Such OPS technology however raises significant transport and Quality of Service QoS) challenges due to technological limitations. To circumvent OPS limitations, we have proposed a new Optical Coarse Packet Switching (OCPS) paradigm, which uses in-band-controlled per-burst switching and advocates traffic control enforcement to achieve high packet-loss performance and differentiated services. Based on OCPS, we have constructed an experimental IP-over-WDM network, referred to as OPSINET. OPSINET consists of two major types of nodes- edge routers, and Optical Label Switched Routers (OLSRs), and is facilitated with an out-of-band Generalized Multi-protocol Label Switching (GMPLS) control network. In this paper, we first introduce the OCPS paradigm. We then present the architecture of OPSINET, describe the in-band header/payload modulation technique, and detail the operations of the edge routers, OLSRs, and GMPLS control.
OPTUNS: Optical Edge Datacenter Network Architecture and Prototype Testbed for Supporting 5G
(2019-01-01)
Yuang, Maria
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Tien, Po-Lung
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Ruan, Wei-Zhang
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Lin, Tien-Chien
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Wen, Shao-Chun
We present the architecture/testbed of an SDN-based optical-tunnel-network system (OPTUNS) for 5G edge-datacenters. Benchmarking results show that, compared to electrical-spine-leaf datacenter-network, OPTUNS achieves 82.6% power saving and significantly lower mean/p99 latency under high traffic load/locality.
OPTUNS: Optical intra-data center network architecture and prototype testbed for a 5G edge cloud [Invited]
(2020-01-01)
Yuang, Maria
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Tien, Po-Lung
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Ruan, Wei-Zhang
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Lin, Tien-Chien
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Wen, Shao-Chun
An edge data center (EDC) network infrastructure is required to flexibly deliver massive bandwidth and ultralow latency for a 5G edge cloud. Existing electrical-switching-based infrastructure, however, has been shown incapable of meeting such requirements. In this paper, we present an EDC network architecture and prototype testbed, referred to as the intelligence-defined optical tunnel network system (OPTUNS). OPTUNS consists of a set of optical switching subsystems that operate collectively to facilitate packet transport through logical wavelength-based optical tunnels. These optical tunnels are governed by a software-defined-networking-based intelligent tunnel control system, in a proactive manner. As such, optical tunnels are always made available whenever needed. In essence, OPTUNS boasts several crucial features, including high scalability, massive wavelength reuse (yielding high bandwidth), proactive optical tunnel control (yielding ultralow latency), and fault tolerance. We have built an OPTUNS testbed, including 30 optical switching subsystem prototypes, that interconnect a total of 25 racks (400 servers). Benchmarking results show that OPTUNS achieves 82.6% power saving compared with electrical spine-leaf networks. Further, our NetPipe-based experimental results show that OPTUNS invariably achieves mean and p99 end-to-end latencies of less than 17 mu s, regardless of traffic load and locality. (C) 2019 Optical Society of America
Parallel Prioritized Flow Scheduling for Software Defined Data Center Network
(2013)
Ke, Bo-Yu
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Tien, Po-Lung
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Hsiao, Yu-Lin
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
Prioritized flow scheduling is essential for providing QoS differentiation and energy saving in data center network. While dynamically manipulating the routing paths of incoming flows becomes practical via enabling technology of software-defined network (SDN), scheduling a large amount of flows in real time remains challenging. In this paper, we propose an Iterative Parallel Grouping Algorithm (IPGA) to the prioritized flow-scheduling problem. Thanks to the inherent nature of parallelism, the IPGA-based flow scheduler not only performs fast scheduling but also can be efficiently realized by a CUD A system within the SDN controller. Via simulations, we demonstrate that the IPGA scheduler achieves QoS differentiation and promising energy saving for a Fat-tree-based network.