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Broadband access technology for passive optical network
(2009-01-01)
Chi, Sien
;
Yeh, Chien-Hung
;
Chow, Chi-Wai
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光電工程學系
;
Department of Photonics
We will introduce four related topics about fiber access network technologies for PONs. First, an upstream signal power-equalizer is proposed and designed using a FP-LD in optical line terminal applied to the TDM-PON, and a 20dB dynamic upstream power range from -5 to -25dBm having a 1.7dB maximal power variation is retrieved. The fiber-fault protection is also an important issue for PON. We investigate a simple and cost-effective TDM/WDM PON system with self-protected function. Next, using RSOA-based colorless WDM-PON is also demonstrated. We propose a cost-effective CW light source into RSOA for 2.5Gb/s upstream in WDM-PON together with self-healing mechanism against fiber fault. Finally, we investigate a 4Gb/s OFDM-QAM for both upstream and downstream traffic in long-reach WDM/TDM PON system under 100km transmission without dispersion compensation. As a result, we believe that these key access technologies are emerging and useful for the next generation broadband FTTH networks.
A Flexible and Reliable 40-Gb/s OFDM Downstream TWDM-PON Architecture
(2015-12-01)
Yeh, Chien-Hung
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Chow, Chi-Wai
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Yang, Ming-Hsiao
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Hsu, Dar-Zu
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光電工程學系
In this paper, a flexible and reliable 40-Gb/s time and wavelength division multiplexing passive optical network (TWDM-PON) architecture is proposed and demonstrated. Here, a 4 x 10 Gb/s orthogonal frequency-division multiplexing (OFDM) downstream signal is achieved by utilizing four 2.5-GHz directly modulated lasers in the optical line terminal. A reflective optical semiconductor amplifier is utilized in each optical network unit to serve as upstream transmitter (Tx) transmitting 2.5-Gb/s on-off keying (OOK) and 10-Gb/s OFDM upstream traffic, respectively. In addition, the dynamic bandwidth (capacity) allocation and fiber fault protection also can be achieved by applying the new proposed PON architecture with software-defined networking approach.
Cost-Effective Mobile Backhaul Network Using Existing ODN of PONs for the 5G Wireless Systems
(2015-12-01)
Sung, Jiun-Yu
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Chow, Chi-Wai
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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.
Visible Light Communication Using Receivers of Camera Image Sensor and Solar Cell
(2016-02-01)
Liu, Yang
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Chen, Hung-Yu
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Liang, Kevin
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Hsu, Chin-Wei
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Chow, Chi-Wai
We propose an electronic label and sensor system using visible light communication (VLC). The downlink signal is transmitted by a white-light light-emitting diode (LED) lamp that can provide lighting, VLC, and energy harvesting for mobile devices. The downlink is received by a solar cell. The uplink can be captured by a surveillance camera image sensor. However, using the camera image sensor as a VLC receiver (Rx) is challenging since the data rate is limited by the frame rate and due to uneven light exposure. The rolling shutter effect of the image sensor can be used to increase the data rate. In this paper, we propose and demonstrate how to demodulate the obtained rolling shutter pattern using a second-order polynomial (SOP) extinction ratio (ER) enhancement scheme, together with iterative and modified quick adaptive thresholding schemes. The ER enhancement scheme can significantly reduce the large ER fluctuation. Experimental results show that by using the proposed SOP ER enhancement scheme, the bit error rate (BER) improvement can be up to two orders of magnitude. We also believe that the proposed electronic label and sensor system may be applicable to Internet-of-Things sensing networks for connecting a number of mobile devices.
Visible-light communication multiple-input multiple-output technology for indoor lighting, communication, and positioning
(2015-12-01)
Liu, Yang
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Hsu, Chin-Wei
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Chen, Hung-Yu
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Liang, Kevin
;
Chow, Chi-Wai
Visible-light communication (VLC) is license free and electromagnetic-interference free; it thus can be deployed in radio-frequency forbidden areas. The light-emitting diode (LED) system providing simultaneously lighting, VLC, and positioning is highly desirable for providing real-time tracking, monitoring, and navigating with very little extra cost. We propose and demonstrate a multiple-input multiple-output (MIMO) VLC-positioning system using white-light LEDs. Our scheme is based on MIMO to provide both position and VLC. Experimental results show that the proposed MIMO VLC system can achieve a bit-error rate of 10(-10), while the positioning errors are within 1 cm. Numerical analyses are also performed, showing the positioning error can be measured within 1 cm. Further analysis of tilting angle of the receiver is also presented. (C) 2015 Society of Photo-Optical Instrumentation Engineers (SPIE)
Long distance non-line-of-sight (NLOS) visible light signal detection based on rolling-shutter-patterning of mobile-phone camera
(2017-05-01)
Wang, Wei-Chung
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Chow, Chi-Wai
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Wei, Liang-Yu
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Liu, Yang
;
Yeh, Chien-Hung
We propose and demonstrate a long distance non-line-of-sight (NLOS) visible light signal detection based on the rolling shutter patterning using commercial mobile phone camera. By using our improved rolling shutter pattern demodulation algorithm, such as the background compensation (BC) blooming mitigation, extinction-ratio (ER) enhancement and Bradley adaptive thresholding, a 1.5 m NLOS visible signal (at low illumination of 145 lux) can be retrieved. (C) 2017 Optical Society of America
Visible light communications using predistortion signal to enhance the response of passive optical receiver
(2016-01-01)
Liu, Yang
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Chen, Hung-Yu
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Liang, Kevin
;
Wei, Liang-Yu
;
Chow, Chi-Wai
Traditional visible light communication (VLC) uses positive-intrinsic-negative photodiode (PD) or avalanche PD as the optical receivers (Rx). We demonstrate using a solar cell as the VLC Rx. The solar cell is flexible and low cost and converts the optical signal into an electrical signal directly without the need of external power supply. In addition to acting as the VLC passive Rx, the converted electrical signal from the solar cell can charge up the battery of the Rx nodes. Hence, the proposed scheme can be a promising candidate for the future Internet of Things network. However, a solar cell acting as a VLC Rx is very challenging, since the response of the solar cell is limited. Here, we propose and demonstrate using predistortion to significantly enhance the solar cell Rx response for the first time up to the authors' knowledge. Experimental results show that the response of the solar cell Rx is significantly enhanced; and the original 2-kHz detection bandwidth of the solar cell can be enhanced by 250 times for receiving 500-kbit/s VLC signal at a transmission distance of 1 m. The operation principle, the generated voltage by the solar cell, and the maximum data rates achieved at different transmission distances are also studied. (C) 2016 Society of Photo-Optical Instrumentation Engineers (SPIE)
Comparison of thresholding schemes for visible light communication using mobile-phone image sensor
(2016-02-08)
Liu, Yang
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Chow, Chi-Wai
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Liang, Kevin
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Chen, Hung-Yu
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Hsu, Chin-Wei
Based on the rolling shutter effect of the complementary metal-oxide-semiconductor (CMOS) image sensor, bright and dark fringes can be observed in each received frame. By demodulating the bright and dark fringes, the visible light communication (VLC) data logic can be retrieved. However, demodulating the bright and dark fringes is challenging as there is a high data fluctuation and large extinction ratio (ER) variation in each frame due. Hence proper thresholding scheme is needed. In this work, we propose and compare experimentally three thresholding schemes; including third-order polynomial curve fitting, iterative scheme and quick adaptive scheme. The evaluation of these three thresholding schemes is performed. (C) 2016 Optical Society of America
Service integrated access network using highly spectral-efficient MASK-MQAM-OFDM coding
(2013-03-11)
Sung, Jiun-Yu
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Chow, Chi-Wai
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Yeh, Chien-Hung
;
Wang, Yin-Chen
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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
Light Encryption Scheme Using Light-Emitting Diode and Camera Image Sensor
(2016-02-01)
Liu, Yang
;
Liang, Kevin
;
Chen, Hung-Yu
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Wei, Liang-Yu
;
Hsu, Chin-Wei
Visible light communication (VLC) is regarded as relatively secure communication when compared with other wireless communications using radio frequency (RF). However, due to the visual nature, the VLC signals are still subject to eavesdropping when they are emitted by the light source. Here, we propose a light encryption scheme using devices having light-emitting diode (LED) and a camera image sensor, such as a mobile phone. The original visible signal sending from the lamp can be first received by the proposed light encrypter. The information can be encrypted and then emitted. The light encrypter acts as an encryption gateway for signals in optical domain. The rolling shutter effect of the complementary metal-oxide semiconductor (CMOS) camera in the mobile phone can be used. By demodulating the rolling shutter pattern, the data information can be obtained. We also propose and demonstrate using the Otsu thresholding scheme to define the data logic in the rolling shutter pattern. We show that the Otsu scheme is effective for estimating the bit error rate (BER). The optimum number of intervals (segmentations) and the process time of the Otsu method are also studied.

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