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Now showing 1 - 10 of 17

Cost-Effective Mobile Backhaul Network Using Existing ODN of PONs for the 5G Wireless Systems
(2015-12-01)
Sung, Jiun-Yu
;
Chow, Chi-Wai
;
Yeh, Chien-Hung
;
Liu, Yang
;
Chang, Gee-Kung
An optical distribution network (ODN) sharing scheme to integrate mobile backhaul networks with the existing passive optical network (PON) systems is proposed and demonstrated. With the ODN sharing scheme, the expense of building new fibers for the next-generation fifth-generation (5G) mobile backhaul networks can be reduced. As many wavelengths are allocated to the already deployed PON systems, there remain limited wavelengths for the mobile backhaul systems. Hence, to efficiently increase the serving cell sites of the 5G systems, spectral-efficient orthogonal frequency-division multiplexing (OFDM) is adopted in the mobile backhaul systems. In order to reduce the latency of the system, adaptive adjustment of the OFDM signals for different transmission distances is averted. The OFDM signals are transmitted only using specific available bandwidth. The available bandwidth for each wavelength is studied according to the power fading relationship between the transmission distances and the chirp induced from signal modulation. A proof-of-concept demonstration experiment has been performed. In our results, 20.17 Gb/s with a bit error rate (BER) lower than 3.8 x 10(-3) was realized with a split ratio of 256 and a 40-km transmission distance of the PON ODN. Hence, each wavelength can support about 20, six, and two nodes for the IMT-advanced, current Long-Term Evolution-Advanced (LTE-A) systems, and the expected 5G systems, respectively.
Service integrated access network using highly spectral-efficient MASK-MQAM-OFDM coding
(2013-03-11)
Sung, Jiun-Yu
;
Chow, Chi-Wai
;
Yeh, Chien-Hung
;
Wang, Yin-Chen
;
光電工程學系
A highly spectral-efficient M-ary amplitude shift keying M-ary quadrature amplitude modulation orthogonal frequency division multiplexing (MASK-MQAM-OFDM) was proposed for the access network. With the highly spectral-efficient characteristic of MASK-MQAM-OFDM, seamless integration among passive-optical network (PON), wireless fiber-to-the-antenna (FTTA), and optical wireless visible light communication (VLC) can be achieved without using extra bandwidth for different services. A proof-of-concept experiment was demonstrated. The relation between the spectral efficiency of the MASK-MQAM-OFDM and the upstream signal performance was also discussed. (c) 2013 Optical Society of America
Polarization-Insensitive Remote Access Unit for Radio-Over-Fiber Mobile Fronthaul System by Reusing Polarization Orthogonal Light Waves
(2016-02-01)
Wu, Beilei
;
Sung, Jiun-Yu
;
Yan, Jhih-Heng
;
Xu, Mu
;
Wang, Jing
To reduce the complexity and cost of remote access units (RAUs), colorless transport architecture is preferred in a wavelength-division multiplexing (WDM) system. The wavelength-reuse technique is commonly adopted to realize colorless RAUs. However, in traditional approaches, RAUs employ crystal-based Mach-Zehnder modulators (MZMs) to modulate the distributed carriers. Hence, polarization tracking systems are necessary to align the polarization state of the distributed carriers with the MZM principal axis. This increases the cost of the RAUs. In this paper, a full-duplex millimeter-wave (MMW) radio-over-fiber (RoF) access architecture employing polarization-insensitive RAUs is proposed. In our proposed RAUs, the upstream signals are generated using polarization-orthogonal lights, and the performance of the upstream signals is independent of the polarization state of the MZM input lights. The proposed system is mathematically formulated and experimentally demonstrated. The 1.2-Gb/s quadrature phase-shift keying (QPSK) orthogonal frequency-division multiplexing (OFDM) downstream signal at the 60-GHz band and 5-Gb/s on-off keying (OOK) polarization-insensitive upstream signal over a 15-km standard single-mode fiber (SSMF) are demonstrated. In our results, a polarization insensitive RAU is successfully obtained. The power penalty resulting from the interference of downstream signal is about 0.4 and 0.6 dB with a bit error rate (BER) of 10(-9) in back-to-back and 15-km fiber transmission, respectively.
Network Architecture of Bidirectional Visible Light Communication and Passive Optical Network
(2016-06-01)
Chow, Chi-Wai
;
Yeh, Chien-Hung
;
Liu, Yang
;
Hsu, Chin-Wei
;
Sung, Jiun-Yu
Network architectures to combine the fiber network outside the building and the visible light communication (VLC) access network inside the building are important for effectively distributing the high-capacity data to different users. In this paper, we propose a bidirectional network combining the VLC access network and the time-wavelength-division-multiplexed passive optical network (TWDM-PON). Orthogonal frequency division multiplexed modulation is used since it offers high spectral efficiency for both the TWDM-PON and the VLC access network. Low-cost phosphor-based white-light light-emitting diodes are (LEDs) used; hence, the VLC access network can combine with the lighting systems.
Two-level modulation scheme to reduce latency for optical mobile fronthaul networks
(2016-10-31)
Sung, Jiun-Yu
;
Chow, Chi-Wai
;
Yeh, Chien-Hung
;
Chang, Gee-Kung
;
光電工程學系
A system using optical two-level orthogonal-frequency-division-multiplexing (OFDM) -amplitude-shift-keying (ASK) modulation is proposed and demonstrated to reduce the processing latency for the optical mobile fronthaul networks. At the proposed remote-radio- head (RRH), the high data rate OFDM signal does not need to be processed, but is directly launched into a high speed photodiode (HSPD) and subsequently emitted by an antenna. Only a low bandwidth PD is needed to recover the low data rate ASK control signal. Hence, it is simple and provides low-latency. Furthermore, transporting the proposed system over the already deployed optical-distribution-networks (ODNs) of passive-optical-networks (PONs) is also demonstrated with 256 ODN split-ratios. (C) 2016 Optical Society of America
Design and characterization of large-core optical fiber for Light Peak applications
(2012-01-01)
Chow, Chi-Wai
;
Yeh, Chien-Hung
;
Yang, Ling-Gang
;
Sung, Jiun-Yu
;
Huang, Sung-Ping
Bandwidth demand for transferring data among different consumer electronic products is increasing rapidly. Due to issues of high propagation loss, electromagnetic interference, and limited bandwidth-distance product of the present copper-based electrical cables, consumer electronic devices may not provide the bandwidth required for future high-capacity applications. The Intel Corporation has proposed Light Peak technology, allowing data transfer between electronic devices at 10 Gb/s in optical domain. To establish a reliable Light Peak connection, robust optical fiber is highly required. In this paper, we discuss the fabrication and characterization of a new type of 80-mu m large-core optical fiber. We perform 10 Gb/s bit-error-rate measurements using 850 and 1550-nm transceivers. The results show that even though we have enlarged the fiber core diameter by 60% (from 50 to 80 mu m) in order to increase the laser-to-fiber alignment tolerance, transmission bandwidth and distance required by Light Peak can still be achieved in this new type of large-core optical fiber. (C) 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI: 10.1117/1.OE.51.1.015006]
Stable and Wavelength-Tunable Self-Injected Reflective Semiconductor Optical Amplifier-Based Fiber Laser
(2015-08-01)
Wu, Yu-Fu
;
Yeh, Chien-Hung
;
Chow, Chi-Wai
;
Sung, Jiun-Yu
;
Chen, Jing-Heng
In this investigation, we propose and demonstrate a stable and wavelength-tunable self-injected reflective semiconductor optical amplifier (RSOA)-based laser by using the Faraday rotator mirror (FRM) and the fiber mirror (FM) serving as a reflected element, respectively. Here, a 1.2-GHz RSOA can be enhanced to similar to 3 GHz by utilizing a self-injected mechanism. In the measurement, applying the optical orthogonal frequency-division multiplexing quadrature amplitude modulation (OFDM-QAM) with a bit-loading algorithm on the self-injected RSOA directly, the proposed laser can achieve a 3.5-Gb/s data rate in a 20-km single-mode-fiber transmission below a forward error correction (FEC) threshold. Moreover, the related output performance of the proposed RSOA-based laser is also discussed, whereas the FRM and the FM are utilized for comparisons.
Design of Visible Light Communication System for Maintaining Uniform Data Rate
(2014-01-01)
Sung, Jiun-Yu
;
Lin, Wan-Feng
;
Wu, Yu-Fu
;
Chow, Chi-Wai
;
Yeh, Chien-Hung
Light-emitting diode (LED) is gradually replacing the fluorescent lamp for lighting. Higher modulation bandwidth of LEDs makes the additional application of visible light communication (VLC) possible. Every location of a VLC system should be provided by equal data rate for smooth communication. However, locations away from the LED lamp have less power. These low-power locations have lower signal-to-noise ratio (SNR); and hence lower data rate can be achieved. For achieving high capacity VLC, strategies should be adequately provided to mitigate this problem. Moreover, for some real-time continuous applications, such as video and voice, latency reduction plan should also be considered. In this paper, an orthogonal frequency-division multiplexing access (OFDMA) based system was proposed to solve the above problem. Because we do not use time-division multiplexing access (TDMA) based system, the latency issue can be reduced. The OFDMA based system is also beneficial for large scale operation because the user bandwidth is not reduced by TDM mechanism. Signal-to-noise-plus-interference ratio (SNIR) distribution of the VLC system is designed to ensure uniform and optimal system capacity. Discrete multi-tone (DMT) is used for this VLC system. The DMT subcarriers are bit-loaded depending on the LED frequency response. More subcarriers are allocated for communication at low SNIR locations. Hence, nearly equal data rate can be provided everywhere. Demonstration of 17 Mb/s/LED data rate was provided.
A secure WDM ring access network employing silicon micro-ring based remote node
(2014-08-01)
Sung, Jiun-Yu
;
Chow, Chi-Wai
;
Yeh, Chien-Hung
;
Xu, Ke
;
Hsu, Chin-Wei
A secure and scalable wavelength-division-multiplexing (WDM) ring-based access network is proposed and demonstrated using proof-of-concept experiments. In the remote node (RN), wavelength hopping for specific optical networking unit (ONU) is deployed by using silicon micro-ring resonators (SMR). Using silicon-based devices could be cost-effective for the cost-sensitive access network. Hence the optical physical layer security is introduced. The issues of denial of service (DOS) attacks, eavesdropping and masquerading can be made more difficult in the proposed WDM ring-based access network. Besides, the SMRs with different dropped wavelengths can be cascaded, such that the signals pass through the preceding SMRs can be dropped by a succeeding SMR. This can increase the scalability of the RN for supporting more ONUs for future upgrade. Here, error-free 10 Gb/s downlink and 1.25 Gb/s uplink transmission are demonstrated to show the feasibility of the proposed network. (C) 2014 Elsevier Inc. All rights reserved.
Is blue optical filter necessary in high speed phosphor-based white light LED visible light communications?
(2014-08-25)
Sung, Jiun-Yu
;
Chow, Chi-Wai
;
Yeh, Chien-Hung
;
光電工程學系
;
Department of Photonics
Optical blue filter is usually regarded as a critical optical component for high speed phosphor-based white light emitting diode (LED) visible-light-communication (VLC). However, the optical blue filter plays different roles in VLC when using modulations of on-off keying (OOK) or discrete multi-tone (DMT). We show that in the DMT VLC system, the blue optical filter may be unnecessary, and even degrade the transmission performance (by reducing the optical signal-to-noise ratio (SNR)). Analyses and verifications by experiments are performed. To the best of our knowledge, this is the first time the function of blue filters in VLC is explicitly analyzed. (C) 2014 Optical Society of America

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