Browsing by Author "Lin, Chi-Hsiang"

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43.63-Gbit/s Multiple-User SC-FDMA PON With Sub-Nyquist Receiver and PAPR Reduction
(2018-10-01)
Lin, Chi-Hsiang
;
Fang, Ruei
;
Lin, Chun-Ting
;
Wei, Chia-Chien
;
Chi, Sien
In this letter, we propose a novel delay-division-multiplexing (DDM) scheme to enable SC-FDMA PON with a sub-Nyquist sampling rate ADC and lower PAPR, named time-interleaved FDMA (TI-FDMA). The proposed pre-processing method reduces the sampling rate of the ADC to 1/2 similar to 1/32 of the Nyquist sampling rate. The FFT size can be reduced to 1/32 (i.e., from 1024 to 32) due to lower sampling ratio and each user just needs to recover and demodulate their corresponding data without any additional DSP, which greatly reduces the complexity of the receiver. Meanwhile, the proposed TI-FDMA has lower PAPR than traditional localized FDMA (L-FDMA), interleaved FDMA (I-FDMA), and OFDM. Such the PAPR reduction makes TI-FDMA support the modulation format of 1 order higher compared to OFDM, thereby, leading to 12.5% capacity improvement. Employing the proposed scheme, up to 43.63-Gbps PON is experimentally demonstrated, and each of 32 users requires only 0.5-GSample/s ADC.
43.63-Gbit/s Multiple-User SC-FDMA PON with sub-Nyquist Receiver and PAPR Reduction
(2018-01-01)
Chang, Hao-Hsiang
;
Lin, Chi-Hsiang
;
Fang, Ruei
;
Lin, Chun-Ting
;
Wei, Chia-Chien
We demonstrate 43.63-Gbps SC-FDMA with 0.5-GSample/s sampling-rate receiver (1/32 Nyquist sampling rate) for each 32-user, which was experimentally demonstrated in commercial optical transmitter and receiver. A brief introduction of traditional SC-FDMA including L-FDMA and I-FDMA is contained. Meanwhile, a PAPR reduction is included in the proposed SC-FDMA system. The method of PAPR reduction makes the PAPR of SC-FDMA be isolated with the number of users and be lower than that of OFDM over 1-dB. Compared to OFDM, such reduction enables SC-FDMA to carry higher-order modulation format, achieving 12.5% capacity improvement (i.e. increases from 37.76 Gbit/s to 43.63 Gbit/s). Moreover, receivers' FFT size will be reduce to 1/32 of that in conventional SC-FDMA. We also compare results with L-FDMA, I-FDMA, and OFDM utilizing high sampling-rate ADC.
60-GHz Millimeter-wave Over Fiber with Directly Modulated Dual-mode Laser Diode
(2016-06-14)
Tsai, Cheng-Ting
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Lin, Chi-Hsiang
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Lin, Chun-Ting
;
Chi, Yu-Chieh
;
Lin, Gong-Ru
A directly modulated dual-mode laser diode (DMLD) with third-order intermodulation distortion (IMD3) suppression is proposed for a 60-GHz millimeter-wave over fiber (MMWoF) architecture, enabling new fiber-wireless communication access to cover 4-km single-mode-fiber (SMF) and 3-m wireless 16-QAM OFDM transmissions. By dual-mode injection-locking, the throughput degradation of the DMLD is mitigated with saturation effect to reduce its threshold, IMD3 power and relative intensity noise to 7.7 mA, -85 dBm and -110.4 dBc/Hz, respectively, providing huge spurious-free dynamic range of 85.8 dB/Hz(2/3). This operation suppresses the noise floor of the DMLD carried QPSK-OFDM spectrum by 5 dB. The optical receiving power is optimized to restrict the power fading effect for improving the bit error rate to 1.9 x 10(-3) and the receiving power penalty to 1.1 dB. Such DMLD based hybrid architecture for 60-GHz MMW fiber-wireless access can directly cover the current optical and wireless networks for next-generation indoor and short-reach mobile communications.
60-GHz optical/wireless MIMO system integrated with optical subcarrier multiplexing and 2x2 wireless communication
(2015-05-04)
Lin, Chi-Hsiang
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Lin, Chun-Ting
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Huang, Hou-Tzu
;
Zeng, Wei-Siang
;
Chiang, Shou-Chih
This paper proposes a 2x2 MIMO OFDM Radio-over-Fiber scheme based on optical subcarrier multiplexing and 60-GHz MIMO wireless transmission. We also schematically investigated the principle of optical subcarrier multiplexing, which is based on a dual-parallel Mach-Zehnder modulator (DP-MZM). In our simulation result, combining two MIMO OFDM signals to drive DP-MZM gives rise to the PAPR augmentation of less than 0.4 dB, which mitigates nonlinear distortion. Moreover, we applied a Levin-Campello bit-loading algorithm to compensate for the uneven frequency responses in the V-band. The resulting system achieves OFDM signal rates of 61.5-Gbits/s with BER of 10(-3) over 25-km SMF transmission followed by 3-m wireless transmission. (C) 2015 Optical Society of America
APD-based Delay-Division-Multiplexing OFDM-PONs
(2018-01-01)
Hsu, Jhih-Hao
;
Yu, Min
;
Chia-Chien
;
Lin, Chi-Hsiang
;
Lin, Chun-Ting
Based on pre-allocated relative sampling delays among optical network users (ONUs) in an orthogonal frequency division multiplexing (OFDM) passive optical network (PON), the delay-division-multiplexing (DDM) technique employs signal pre-processing to enable demand data to be received by sub-Nyquist analog-to-digital sampling. This work employed an avalanche photodiode (APD) in a DDM-OFDM-PON to achieve higher loss budget, compared to a p-i-n photodiode (PIN). To successfully enable the pre-processing, however, the knowledge of channel response is required; thus, it is critical to estimate complete channel response in DDM-OFDM systems under the constraint of sub-Nyquist sampling. To avoid spectral overlapping in channel estimation, the subcarriers of training symbols in different frequency zones are allocated to different time slots. Unfortunately, this scheme may sustain inaccurate channel estimation due to different degrees of APD saturation for training subcarriers at different frequency zones, leading to significant penalty in performance. Thus, careful control of electrical driving power and optical received power for the training symbols will be important to reduce the impact of saturation on channel estimation, thereby improving transmission performance. We experimentally examined the impact of the accuracy of channel estimation in a 25-Gbps APD-based OFDM-PON. Compared to a PIN, we successfully demonstrated the DDM scheme based on an APD and 1/32 of Nyquist rate with 5-dB improvement in sensitivity after 25-km fiber transmission.
Delay Division Multiplexing DFT Spread FDMA PON by Sub-Nyquist Sampling Rate Receiver
(2016)
Bai, Guang-Fu
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Lin, Chun-Ting
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Lin, Chi-Hsiang
;
Ho, Chun-Hung
;
Wei, Chia-Chien
We propose time delay division DFT-S FDMA PON scheme. Each ONU can receive data by using ADCs of 1/2 similar to 1/32 Nyquist Sample Rate such that DFT and IDFT are unnecessary for de-mapping and picking out signals.
DFT/IDFT-free receiving scheme for spread-OFDM signals employing low-sampling-rate ADCs
(2017-10-30)
Lin, Chi-Hsiang
;
Lin, Chun-Ting
;
Wei, Chia-Chien
;
Chi, Sien
;
光電系統研究所
This paper presents a DFT/IDFT-free receiving scheme for spread-OFDM signals. Leveraging sub-Nyquist sampling and proper sampling delay, the proposed scheme enables each user to receive the requested data without the need for DFT and IDFT; thus, the complexity at receiver can be greatly reduced. Nonetheless, DC component is altered in an AC coupling system, such that severe waveform distortion is caused when the process of DFT/IDFT is omitted. Thus, a DC-zeroing algorithm is proposed to guarantee constant DC after sub-Nyquist sampling, thereby eliminating such distortion. To experimentally verify the concept of proposed scheme, a 27.15-Gbit/s optical spread-OFDM signal was transmitted over fiber and received by the DFT/IDFT-free scheme with sub-Nyquist sampling. More users will reduce the required sampling rate at receiver; for the case of 16 users, the required sampling rate for the 27.15-Gbit/s signal is as low as 1 GSample/s. The experimental results show that error-free transmission was achievable, and the penalty due to lowering sampling rate (i.e., increasing the number of users) is insignificant. (C) 2017 Optical Society of America
Employing Hybrid sub-Nyquist Sampling Rates to Support Heterogeneous Services of Varying Capacity in 25-Gbps DDM-OFDM-PON
(2018-04-01)
Hsu, Jhih-Hao
;
Yu, Min
;
Wei, Chia-Chien
;
Lin, Chi-Hsiang
;
Lin, Chun-Ting
Delay-division-multiplexing (DDM) involves the use of signal preprocessing for the detection of data via sub-Nyquist analog-to-digital sampling, based on preallocated relative sampling delays among optical network users (ONUs) in an orthogonal frequency-division multiplexing (OFDM) passive optical network (PON). If a DDM-PON consists of M virtual groups, the sampling rate at the receivers is only 1/M of the Nyquist rate, but the maximum capacity of each ONU is fixed at 1/M of the total capacity. In this study, we developed a novel DDM scheme that uses hybrid sub-Nyquist sampling rates to accommodate heterogeneous services of different capacities in an OFDM-PON. To equalize the transmission performances using hybrid sub-Nyquist sampling rates, the modification of preprocessing was proposed, and its necessity was demonstrated. Without loss of generality, we experimentally demonstrated a 25-Gbps DDM-OFDM-PON using hybrid sampling at 1/2, 1/8, and 1/32 (or 1/8, 1/16, and 1/32) of the Nyquist rate. Compared to a DDM-PON with a fixed sub-Nyquist rate, the received signals based on hybrid sub-Nyquist sampling rates show similar sensitivities. A loss budget of 26 dB was experimentally achieved using all sub-Nyquist sampling rates after employing the modified preprocessing.
Long-reach 60-GHz MMWoF link with free-running laser diodes beating
(2018-09-12)
Tsai, Cheng-Ting
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Li, Chien-Cheng
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Lin, Chi-Hsiang
;
Lin, Chun-Ting
;
Chi, Sien
With the remote beating of two mutually incoherent laser carriers, the local-oscillator-free long-reach millimeter-wave over fiber (MMWoF) link at 60-GHz band is demonstrated. The unique schemes of the proposed MMWoF are the wavelength-locked colorless laser diode (CLD) modulator, the mutually incoherent optical carrier for heterodyne MMW generation, and the square-law power envelope detection at receiving end. By directly encoding the single-mode with the CLD modulator, the singlecarrier modulated QAM-OFDM data is achieved to release the RF power fading after fiber transmission. The mutually incoherent laser beating enables the optical heterodyne MMW generation with two independent optical carriers, which provides the advantages of local-oscillator-free operation and rules out the requirement of dual-mode optical carrier delivery from central office. At the wireless receiving end, the received QAM-OFDM data is self-down-converted to the baseband by employing the square-law power envelope detection. This eliminates the requirement of local oscillator and rules out the influence of the MMW carrier frequency fluctuation between two mutually incoherent lasers (used at central office and remote node), which effectively provides the MMW carrier immunity against the down-conversion instability caused by clock jitter or carrier incoherence. This architecture ensures the transmission of 16.5-Gbit/s 32-QAM OFDM data over 50 km in SMF and 3 m in free-space with the FEC certificated error vector magnitude of 12%, signal-to-noise ratio (SNR) of 18.4 dB, and bit error rate of 3.8 x 10(-3). For multi-channel DWDM-PON applications, the proposed local-oscillator-free MMWoF link can successfully perform 11 DWDM channels of 32-QAM OFDM data access at 16.5 Gbit/s per channel via the wavelength controlling of the CLD modulation stage and the detuning of the beating carrier at remote node.
Novel DDM-OFDM-PON with Hybrid Sub-Nyquist Sampling Rates Featuring Heterogeneous ONUs with Different Capacities
(2018-01-01)
Hsu, Jhih-Hao
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Yu, Min
;
Wei, Chia-Chien
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Lin, Chi-Hsiang
;
Lin, Chun-Ting
We propose a delay-division-multiplexing-OFDM-PON (DDM-OFDM-PON) with hybrid sub-Nyquist sampling rates, wherein heterogeneous ONUs can request different capacities. 26-dB loss budget in 25-km 25-Gbps DDM-OFDM-PON was achieved using hybrid sampling at 1/32 / 1/16 / 1/8 or 1/32 / 1/8 / 1/2 Nyquist rates.
Novel Detection in V-band MIMO OFDM RoF Systems Using ADCs with Sub-Nyquist Sampling
(2017-01-01)
Huang, Yao-Lun
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Wei, Chia-Chien
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Lin, Chun-Ting
;
Lin, Chi-Hsiang
;
光電系統研究所
A novel detection scheme in :MIMO-OFDM-RoF systems is proposed. Via preprocessing, data are received using sub-Nyquist-sampling ADCs without-MIMO demodulation and extra DSP. Based on 5/32-CiSample/s sampling rate, 50-Gbps 2 x 2 MIMO-OFDM-RoF transmission was successfully demonstrated.
On channel estimation schemes for APD-based DDM-OFDM-PONs under sub-Nyquist sampling
(2018-09-03)
Hsu, Jhih-Hao
;
Yu, Min
;
Liu, Fumin
;
Lin, Chi-Hsiang
;
Lin, Chun-Ting
Implementing preprocessing in a delay-division multiplexing (DDM) orthogonal frequency-division multiplexing (OFDM) passive optical network (PON) requires a priori knowledge of channel responses, which need to be estimated under the constraint of sub-Nyquist analog-to-digital sampling. The localized approach allocates subcarriers in different frequency zones to training symbols in different time slots for channel estimation without spectral overlap. Unfortunately, the localized scheme is susceptible to inaccurate estimation when using an avalanche photodiode (APD), due to variations in APD saturation associated with different training symbols. Instead of localizing all subcarriers of a training symbol in a single frequency zone, we propose distributing training subcarriers through various frequency zones. This distributed scheme would prevent spectral overlap and also reduce the degree of variation in APD saturation, thereby improving the accuracy of channel estimation. Alternatively, we propose an orthogonal scheme in which each training symbol uses all of the subcarriers simultaneously. The orthogonality specified among consecutive training symbols should make it possible to estimate the channel response with low computational complexity. We conducted experiments to compare various schemes used for channel estimation in a 25-Gbps APD-based OFDM-PON. Our results revealed that the orthogonal scheme achieved the best results, and the localized scheme provided the worst channel estimates. We demonstrate the application of the orthogonal scheme in a penalty-free DDM system at 1/32 of the Nyquist rate, which provided a loss budget of 28 dB after fiber transmission over a distance of 25 km. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Simple Receiving Scheme in 100-GHz DD OFDM RoF Systems Employing Low-Sampling-Rate ADCs and Digital Preprocess
(2015)
Liu, Huan-Ching
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Lin, Chi-Hsiang
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Lin, Chun-Ting
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Wei, Chia-Chien
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Huang, Hou-Tzu
A simple low-sampling-rate receiving scheme is proposed for W-hand OFDM-RoF systems, Using the proposed preprocess, aliasing-free suhcarriers can be received, and employing the optimized delays to ADCs can achieve the performance insensitive to sampling rate.
Simplified 27.15 Gbits/s Spread-OFDM PON using DFT/IDFT-free Receiver with 1/16 Sub-Nyquist Sampling Rate
(2017-01-01)
Lin, Chi-Hsiang
;
Lin, Chun-Ting
;
Wei, Chia-Chien
;
Chi, Sien
;
Fang, Ruie
This paper presents 27.15-Gbits/s spread-OFMD PON sub-Nyquist receiver via 1GSampleis ADC for each 32-ONU to demodulate signals, which greatly reduces complexity. Moreover. DC algorithm is proposed to eliminate DC-located distortion caused by sub-Nyquist ADC.
V-band Gapless OFDM RoF System with Power Detector Down-conversion and Novel Volterra Nonlinear Compensation
(2016)
Chiang, Shou-Chih
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Li, Che-Hao
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Lin, Chun-Ting
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Huang, Hou-Tzu
;
Lin, Chi-Hsiang
V-band gapless OFDM RoF system with power detector down-conversion is proposed. We propose and successfully employ a novel Volterra nonlinear compensation to mitigate signal-to-signal beating interference, resulting in 22% data rate improvement with bit-loading algorithm.
V-band gapless OFDM RoF system with power detector down-conversion and novel Volterra nonlinear filtering
(2017-01-15)
Lin, Chun-Ting
;
Chiang, Shou-Chih
;
Li, Che-Hao
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Huang, Hou-Tzu
;
Lin, Chi-Hsiang
This Letter presents a V-band gapless orthogonal frequency division multiplexing (OFDM) RoF system at 60 GHz employing a power detector to support vector signal down-conversion. Additional RF tone is generated and transmitted from a central station to replace the local oscillator at a wireless receiver for power detector down-conversion. To enhance the spectrum efficiency, the gap between the OFDM signal and the RF tone is not needed. However, the down-converted signal will suffer signal-to-signal interference (SSBI). In this Letter, we propose and successfully employ a novel Volterra nonlinear compensation to mitigate SSBI, resulting in a 22% data rate improvement with a bit-loading algorithm. (C) 2017 Optical Society of America
W-band DD-OFDM-RoF System Employing Pilot-aided PAPR Reduction
(2014-01-01)
Huang, Hou-Tzu
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Lin, Chun-Ting
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Liu, Huan-Ching
;
Hsu, Hsun-Hao
;
Wu, Meng-Fan
We propose and experimental demonstrate a high spectral efficiency direct-detection radio-over-fiber (DD-RoF) system in W-band. To overcome the issue of peak-to-average power ratio (PAPR) in orthogonal frequency-division multiplexing (OFDM) signals, this study proposes a pilot-aided PAPR reduction simplified from Tellado's tone reservation. Using a 10-GHz 16-QAM OFDM signal, BER was improved from 1.3 x 10(-3) to 5.0 x 10(-4) over 4-km fiber and 2-m wireless transmission. Using a 32-QAM OFDM signal, the pilot-aided PAPR reduction improved the data rate from 45.2 Gbps to 47.6 Gbps under FEC limits (BER=3.8 x 10(-3)).
W-band OFDM Radio-over-Fiber system with power detector for vector signal down-conversion
(2015-06-01)
Lin, Chun-Ting
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Wu, Meng-Fan
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Ho, Chun-Hung
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Li, Che-Hao
;
Lin, Chi-Hsiang
This Letter proposes a W-band OFDM RoF system at 103.5 GHz employing power detector to support vector signal down-conversion. Additional RF tone is generated and transmitted from central office to replace the local oscillator at a wireless receiver. With a proper frequency gap and power ratio between the RF tone and the OFDM-modulated signal, the impact from signal-to-signal beating interference can be minimized. The data rate can achieve a 40 Gbps 16 QAM OFDM signal over 25 km fiber and 2 m wireless transmission. (C) 2015 Optical Society of America
W-band OFDM RoF System with Simple Envelope Detector Down-Conversion
(2015)
Li, Che-Hao
;
Wu, Meng-Fan
;
Lin, Chi-Hsiang
;
Lin, Chun-Ting
;
光電系統研究所
This article proposes W-hand OFDM RoF system at 103.5 GHz employing envelop detector (ED) down-conversion. It can support vector signal down-conversion and doesn\'t need the LO in BS, The data rate of W-band OFDM signals with 10-GHz bandwidth can achieve 40 Gbps over 25-km fiber and 2-m wireless transmission.