Browsing by Author "Way, WI"

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33-channel 64-QAM signal transmission using a 1.3-mu m semiconductor optical amplifier
(1996-01-01)
Chiang, PY
;
Tai, C
;
Way, WI
;
電信工程研究所
;
電信研究中心
From the network evolution point of view, optical amplifiers in a hybrid fiber coaxial (HFC) system may become extensively deployed at approximately the same time as when analog AM-VSB video signals are all replaced by digital M-QAM or M-VSB signals. This letter demonstrates the feasibility of using a 1.3-mu m semiconductor optical amplifier to transport 33 channels of 64-QAM signals with 30 Mbps/channel. A total system power budget of 20.3 dB was obtained.
740-km transmission of 78-channel 64-QAM signals (2.34 Gb/s) without dispersion compensation using a recirculating loop
(2000-09-01)
Wu, MC
;
Wong, JK
;
Tsai, KT
;
Chen, YL
;
Way, WI
A long-distance 1550-nm subcarrier multiplexed lightwave trunk system that transported 78 channels of 64-QAM signals was demonstrated in a recirculating loop experiment. Each channel can achieve a carrier-to-(noise + nonlinear distortion) ratio of 30 dB after 740-km transmission through conventional single-mode fiber without dispersion compensation.
A novel optical label swapping technique using erasable optical single-sideband subcarrier label
(2000-08-01)
Lin, YM
;
Way, WI
;
Chang, GK
;
電信工程研究所
;
Institute of Communications Engineering
To support optical MultiProtocol Label Switching (MPLS) technology in an optical network, we have demonstrated subcarrier label swapping in a 96.2-km, three-node experiment, by using optical single-sideband modulation and an optical notch filter. At each intermediate switching node, an old subcarrier label can be suppressed by 25 dB, while the burst-mode 2.5-Gb/s payload experienced only 2-dB power loss.
A VLSI architecture design for dual-mode QAM and VSB digital CATV transceiver
(1998-12-01)
Shiue, MT
;
Wang, CK
;
Way, WI
;
電信工程研究所
;
Institute of Communications Engineering
In this paper, a transceiver VLSI architecture is proposed for high speed digital CATV modems, which can perform both the QAM and the VSB transmissions [1], [2]. The proposed architecture of all-digital dual-mode QAM/VSB receiver consists of digital AGC, digital demodulator, fractionally spaced blind equalizer and DFE, digital carrier recovery, and symbol timing recovery. Finite word-length simulation results show that the proposed architecture can achieve an SNR 29 dB for both the 64-QAM mode and 8-VSB mode when the 10 bit ADC input signal SNR is 36 dB, and there are +/-6 kHz of carrier frequency offset, +/- 110 ppm of symbol rate offset, and -82 dBc carrier phase-jitter at 10 kHz away from the nominal carrier frequency.
Alignment monitoring technique for pulse carver and data modulator in RZ-DPSK systems using an optical frequency discriminator
(2006-05-01)
Tsai, KT
;
Lu, GW
;
Chen, LK
;
Way, WI
;
電信工程研究所
A technique for monitoring the timing alignment between a pulse carver and a phase modulator in return-to-zero differential phase-shift keying systems is proposed. An optical frequency discriminator and a microwave detector centered at a half of the phase modulation data rate are used to monitor the spectrum broadening caused by timing misalignment., The proposed method has a large detection dynamic range and is polarization-independent.
Chromatic-dispersion monitoring using an optical delay-and-add filter
(2005-11-01)
Tsai, KT
;
Way, WI
;
電信工程研究所
;
Institute of Communications Engineering
A novel postdetection method based on an optical delay-and-add filter (DAF) is proposed for dispersion monitoring at 40 Gb/s or beyond. The proposed method can be used with or without a pilot tone and works well even when there exists a residual chirp due to the finite direct current (DC) extinction ratio of a Mach-Zehnder (MZ) modulator or self-phase modulation (SPM). Several modulation formats, including conventional nonreturn to zero (NRZ), return to zero (RZ), carrier-suppressed RZ (CSRZ), RZ differential phase shift keying (RZ-DPSK), and CSRZ-DPSK are used to numerically demonstrate the feasibility of this technique without using a pilot tone.
CSO distortions due to the combined effects of self- and external-phase modulations in long-distance 1550-nm AM-CATV systems
(1999-06-01)
Wu, MC
;
Wang, CH
;
Way, WI
;
電信工程研究所
;
Institute of Communications Engineering
We found that the combined effects of self- and external-phase modulations must be considered in order to precisely predict the composite second-order distortions in a long-distance 1550-nm externally modulated AM-cable TV (CATV) system, especially when the applied phase modulation index and modulating tone frequency to the integrated phase modulator are high, This result has important implications to the optimum design of 1550-nm transmitter for long-distance Am- and QAM-CATV systems.
Demonstration of gigabit WDMA networks using parallelly processed subcarrier hopping pilot-tone (P-3) signaling technique
(1996-07-01)
Wang, BH
;
Yen, KY
;
Way, WI
;
電信工程研究所
;
電信研究中心
An extremely short header transmission and processing time in a gigabit wavelength-division-multiple-access (WDMA) network has been experimentally demonstrated. This was achieved by using parallelly processed subcarrier hopping pilot-tones in combination with an array of detectors and RF switches. The results showed that, without considering the time consumed in an arbitration circuit, the total processing time of the hopping pilot-tone headers was as short as 40 ns which is independent of the number of network nodes and data transmission rate.
Demonstration of gigabit WDMA networks using parallelly processed subcarrier hopping pilot-tone (P-3) signaling technique
(1996-07-01)
Wang, BH
;
Yen, KY
;
Way, WI
;
電信工程研究所
;
電信研究中心
An extremely short header transmission and processing time in a gigabit wavelength-division-multiple-access (WDMA) network has been experimentally demonstrated. This was achieved by using parallelly processed subcarrier hopping pilot-tones in combination with an array of detectors and RF switches. The results showed that, without considering the time consumed in an arbitration circuit, the total processing time of the hopping pilot-tone headers was as short as 40 ns which is independent of the number of network nodes and data transmission rate.
Design and implementation of ultra-low latency optical label switching for packet-switched WDM networks
(2000-12-01)
Meagher, B
;
Chang, GK
;
Ellinas, G
;
Lin, YM
;
Xin, W
An ultra-low latency, high throughput internet protocol(IP) over wavelength division multiplexing (WDM) packet switching technology for next-generation internet (NGI) applications has been designed and demonstrated. This method overcomes limitations of conventional optical packet switching, which require buffering of packets and synchronization of bits, rind optical burst switching methods that require estimation of delays at each node and for each path. An optical label switching technique was developed to realize flexible bandwidth-on-demand packet transport on a reconfigurable WDM network. The aim was to design a network with simplified protocol stacks, scalability, and data transparency, This network will enable the NGI users to send their data applications at gigabit/second access speed with low and predictable latency (<1 sec per switch node), with a system capacity of beyond multi-Tb/s. Packet forwarding utilizes WDM optical headers that are carried in-band on the same wavelength and modulated out-of-hand in the frequency domain.
Dynamic range and switching speed limitations of an NxN optical packet switch based on low-gain semiconductor optical amplifiers
(1996-04-01)
Tai, C
;
Way, WI
;
交大名義發表
;
光電工程學系
;
National Chiao Tung University
Two important system performance limitations-dynamic range and switching speed-of an integrated packet switch fabric based on low-gain semiconductor optical amplifiers (SOA's) have been examined by using cascaded blocks of an SOA model, which includes transient effect, nonlinear pulse distortion effect, and amplified spontaneous emission (ASE) noise, Low-gain SOA's were used to minimize ASE noise considering that no optical filters can be integrated in an SOA-based switch fabric, The system performance with and without a narrowband optical filter at the receiver were both studied, By assuming fixed wavelength transmitters and no optical filter can be used at the receiving end owing to the unpredictability of arriving packet wavelengths, our simulation results indicate that the dynamic ranges of 4 x 4 and 8 x 8 SOA-based packet switches at 2.5 Gb/s can only be about 3.2 and 0.8 dB, respectively, However, at 155 Mb/s, even without a receiving-end optical filter, the dynamic range of each switch size can be increased by more than 17 dB as compared to the cases of 2.5 Gb/s, Note that the dynamic ranges were estimated under the conditions of a bit error rate (BER) less than or equal to 10(-9) and a pulse distortion ratio less than or equal to 30%. We have also shown that, when an optical filter with a 1 nm bandwidth was used at the receiving end to simulate 1) a circuit-switched condition where the center wavelength of the filter can be adjusted according to the established circuit, or 2) a packet-switched condition where each receiver has a wavelength demultiplexer and a detector array, the dynamic range of 4 x 4 and 8 x 8 switches can be increased to 16.3 and 14 dB, respectively, at 2.5 Gb/s.
Eight-way, 70-km transmission of 33-channel 64-QAM signals utilizing a 1.3-mu m external modulation system and semiconductor optical amplifier
(1996-09-01)
Tai, C
;
Chiang, PY
;
Way, WI
;
電信工程研究所
;
電信研究中心
By using a 1.3-mu m external modulation system and a semiconductor optical amplifier, we experimentally demonstrated the feasibility of broadcasting 33 channels of 64-QAM digital CATV signals to eight 70-km optical fiber links, The presented results show that, with the vast momentum on developing M-QAM modems, potentially low-cost semiconductor optical amplifiers can possibly expedite the penetration pace of optical fibers in broad-band access networks.
Eight-way, 70-km transmission of 33-channel 64-QAM signals utilizing a 1.3-mu m external modulation system and semiconductor optical amplifier
(1996-09-01)
Tai, C
;
Chiang, PY
;
Way, WI
;
電信工程研究所
;
光電工程學系
By using a 1.3-mu m external modulation system and a semiconductor optical amplifier, we experimentally demonstrated the feasibility of broadcasting 33 channels of 64-QAM digital CATV signals to eight 70-km optical fiber links, The presented results show that, with the vast momentum on developing M-QAM modems, potentially low-cost semiconductor optical amplifiers can possibly expedite the penetration pace of optical fibers in broad-band access networks.
Fiber nonlinearity limitations in ultra-dense WDM systems
(2004-06-01)
Wu, MC
;
Way, WI
;
電信工程研究所
;
Institute of Communications Engineering
Transmission performance of ultra-dense 2.5- and 10-Gb/s nonreturn-to-zero intensity-modulated direct-detection wavelength-division-multiplexing systems in various single-mode fibers is investigated. Fundamental limiting factors and their remedies by using optimum dispersion compensation for periodically amplified systems in C band are presented.
Large-signal spurious-free dynamic range due to static and dynamic clipping in direct and external modulation systems
(1998-10-01)
Wang, BH
;
Chiang, PY
;
Kao, MS
;
Way, WI
;
電信工程研究所
Large-signal spurious-free dynamic range (SFDR) is useful in an optical system with a high intensity noise level, which can be due to optical reflections or optical beat interference, and with large modulating signals to achieve sufficient carrier-to-noise ratio (CNR). A closed-form analysis on large-signal SFDR due to static and dynamic clipping for direct and external modulation systems is presented in this paper. The analysis can be applied to laser diodes (LD's) and external modulators with arbitrary transfer functions. We have used the analysis to predict the theoretical upper-bound for large-signal SFDR due to static clipping in an ideal LD add external modulators with various linearization techniques. We have also used the analysis to predict the dynamic-clipping-induced nonlinear distortions (NLD's) id. a weakly clipped LD, and confirm that dynamic clipping is more important to consider than static clipping when weak LD clipping takes place. Large-signal SFDR's in practical LD's and external modulators were also compared. The validity of our analysis is confirmed through computer simulation and actual measurement of clipping-induced NLD's in a typical CATV-quality DFB LD.
Multichannel single-sideband SCM/DWDM transmission systems
(2004-07-01)
Chen, WH
;
Way, WI
;
電信工程研究所
;
Institute of Communications Engineering
To understand the transmission limitation of multiple narrow single-sideband subcarrier-multiplexed (SSB/SCM) signals' this paper first presents a closed-form analysis to predict Mach-Zehnder intensity modulator-induced composite triple beat (CTB), and linear-fiber-dispersion-induced composite second-order (CSO) and CTB distortions. To combine SSB/SCM with dense-wavelength-division-multiplexing, (DWDM) systems, analytical and numerical tools, which are not constrained by any wavelength spacing and modulation frequencies, are used to analyze cross-phase modulation-induced crosstalk. All the analytical and numerical results are verified by computer simulations. Several multichannel SSB/SCM/DWDM systems with transport capacities of 10 or 20 Gb/s per wavelength, with a wavelength spacing of 25, 50, and 100 GHz, are also studied in this paper to understand the fundamental transmission limitations.
Multiple access in the presence of optical-beat and co-channel interference using Walsh-code-based synchronized CDMA technique
(1997-08-01)
Hsiao, CC
;
Wang, BH
;
Way, WI
;
電信工程研究所
;
Institute of Communications Engineering
We experimentally demonstrated the feasibility of using Walsh-code-hased synchronized code-division-multiple access (S-CDMA) technique to achieve multiple access in the presence of optical-beat interference (OBI), This multiple access technique can, thus, be applied to WDMA networks using subcarrier-based common wavelength signaling, or PON's which generally do not have wavelength control on uplink laser diodes.
Multiple access in the presence of optical-beat and co-channel interference using Walsh-code-based synchronized CDMA technique
(1997-08-01)
Hsiao, CC
;
Wang, BH
;
Way, WI
;
交大名義發表
;
電信工程研究所
We experimentally demonstrated the feasibility of using Walsh-code-hased synchronized code-division-multiple access (S-CDMA) technique to achieve multiple access in the presence of optical-beat interference (OBI), This multiple access technique can, thus, be applied to WDMA networks using subcarrier-based common wavelength signaling, or PON's which generally do not have wavelength control on uplink laser diodes.
Novel electro-optical pre-distortion technique and its application in externally modulated CATV transmission systems
(1998)
Tsai, KT
;
Tai, C
;
Way, WI
;
電信工程研究所
;
Institute of Communications Engineering
Conventional linearization techniques such as electrical pre-distortion or optical feedforward methods have been applied to Mach-Zehnder interferometer (MZI) modulators for CATV transmission systems. However, both methods can only ensure that the output of the MZI modulator meet the standard CATV requirements on composite second-order (CSO) and composite triple beat (CTB), but cannot guarantee a satisfactory end-to-end system linearity. In this paper, we propose and demonstrate a novel linearization technique, which can simultaneously suppress the nonlinear distortions (NLDs) generated in a transmission system and increase the received carrier-to-noise ratio (CNR). This technique is based on offsetting the MZI bias voltage from its inflection point. Both analytical and experimental results are presented.
On the validity of using CW tones to test the linearity of multichannel M-QAM subcarrier multiplexed lightwave systems
(2000-04-01)
Wu, MC
;
Chiang, PY
;
Way, WI
;
電信工程研究所
;
Institute of Communications Engineering
This paper investigates the validity of using multiple continuous-wave (CW) tones as the signal source to test the linearity of a multichannel M-ary quadrature-amplitude-modulation (M-QAM) subcarrier multiplexed lightwave system. We consider the following representative optical fiber system nonlinearities: 1) laser clipping and 2) the combined effect of laser frequency chirp and fiber dispersion. Our results show that if all orders of nonlinear distortions (NLD's) in a signal bandwidth are included in the total NLD power, the error caused by replacing M-QAM signals with CW tones can be within measurement uncertainty.