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| 2. |
- Feng, Zhenhua, et al.
(författare)
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Multicore-Fiber-Enabled WSDM Optical Access Network With Centralized Carrier Delivery and RSOA-Based Adaptive Modulation
- 2015
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Ingår i: IEEE PHOTONICS JOURNAL. - : Institute of Electrical and Electronics Engineers (IEEE). - 1943-0655. ; 7:4
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Tidskriftsartikel (refereegranskat)abstract
- We proposed and experimentally demonstrated a wavelength-space division multiplexing (WSDM) optical access network architecture with centralized optical carrier delivery utilizing multicore fibers (MCFs) and adaptive modulation based on reflective semiconductor amplifier (RSOA). In our experiment, five of the outer cores are used for undirectional downstream (DS) transmission only, whereas the remaining outer core is utilized as a dedicated channel to transmit upstream (US) signals. Optical carriers for US are delivered from the optical line terminal (OLT) to the optical network unit (ONU) via the inner core and then transmitted back to the OLT after amplification and modulation by the RSOA in the colorless ONU side. The mobile backhaul (MB) service is also supported by the inner core. Wavelengths used in US transmission should be different from that of the MB in order to avoid the Rayleigh backscattering effect in bidirectional transmission. With quadrature phase-shift keying-orthogonal frequency-division multiplexing (QPSK-OFDM) modulation format, the aggregation DS capacity reaches 250 Gb/s using five outer cores and ten wavelengths, and it can be further scaled to 1 Tb/s using 20 wavelengths modulated with 16 QAM-OFDM. For US transmission, 2.5 Gb/s QPSK-OFDM transmission can be achieved just using a low-bandwidth RSOA, and adaptive modulation is applied to the RSOA to further enhance the US data rate to 3.12 Gb/s. As an emulation of high-speed MB transmission, 48 Gb/s inphase and quadrature (IQ) modulated popularization division multiplexing (PDM)-QPSK signal is transmitted in the inner core of MCF and coherently detected in the OLT side. Both DS and US optical signals exhibit acceptable performance with sufficient power budget.
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| 3. |
- Feng, Z., et al.
(författare)
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A simplified adaptive modulation scheme for RSOA based DDO-OFDM system using CAZAC precoding
- 2016
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Ingår i: 2016 Optical Fiber Communications Conference and Exhibition, OFC 2016. - Washington, D.C. : Institute of Electrical and Electronics Engineers (IEEE).
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Konferensbidrag (refereegranskat)abstract
- We experimentally demonstrated a RSOA based DDO-OFDM system using CAZAC precoding. Adaptive modulation has been simply and efficiently performed after CAZAC precoding to improve the sensitivity and overall data rate thanks to the equalized SNR.
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| 4. |
- Feng, Zhenhua, et al.
(författare)
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Digital Domain Power Division Multiplexing DDO-OFDM Transmission with Successive Interference Cancellation
- 2016
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Ingår i: 2016 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO). - Washington, D.C. : IEEE conference proceedings.
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Konferensbidrag (refereegranskat)abstract
- Two independent 2.5-Gb/s DDO-OFDM signals are simultaneously transmitted over 25km SMF using digital domain power division multiplexing and successive interference cancellation. With optimized power division ratio and enhanced SD-FEC, the spectral efficiency can be doubled.
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| 5. |
- Feng, Zhenhua, et al.
(författare)
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Performance-Enhanced Direct Detection Optical OFDM Transmission With CAZAC Equalization
- 2015
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Ingår i: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 27:14, s. 1507-1510
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Tidskriftsartikel (refereegranskat)abstract
- Direct detection optical orthogonal frequency division multiplexing (DDO-OFDM) transmission with constant amplitude zero autocorrelation (CAZAC) sequence equalization is proposed and experimentally demonstrated. Simulation results show that more than 2-dB peak-to-average power ratio (PAPR) reduction can be realized using CAZAC equalization, and 50-km standard single mode fiber (SSMF) transmission of 4.11-Gb/s QPSK-OFDM can be achieved with bit-error rate (BER) under forward error correction limit. Transmission performance of QPSK-based DDO-OFDM system is analyzed in both OB2B configuration and fiber link with and without CAZAC equalization. More than 2.5-dB optical receiver sensitivity improvements can be obtained thanks to the PAPR reduction enjoyed by CAZAC equalization. Signal-to-noise ratio for every subcarrier derived from error vector magnitude is estimated and its flatness is confirmed to be much improved with CAZAC equalization. The performance improvements brought by CAZAC equalization can be extended to other modulation formats, and 8.22-Gb/s 16-quadratic-amplitude modulation-OFDM signals transmission using CAZAC equalization is demonstrated with over 1.5 dB enhancement in receiver sensitivity.
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| 6. |
- Feng, Z., et al.
(författare)
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Power efficient optical OFDM transmission with phase modulation and direct detection
- 2016
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Ingår i: 2016 21st OptoElectronics and Communications Conference, OECC 2016 - Held Jointly with 2016 International Conference on Photonics in Switching, PS 2016. - : IEEE conference proceedings. - 9784885523052
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Konferensbidrag (refereegranskat)abstract
- Optical OFDM transmission with phase modulation and direct detection (PMDD) is verified by theoretical derivation and simulation. 26.12-Gb/s PMDD 16QAM-OFDM achieves comparable performance to single sideband IMDD 16QAM-OFDM with half of the optical modulation index.
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| 7. |
- Feng, Zhenhua, et al.
(författare)
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SNR equalized optical direct-detected OFDM transmission with CAZAC equalization
- 2015
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Ingår i: CLEO. - : Optica Publishing Group.
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Konferensbidrag (refereegranskat)abstract
- 50Km SSMF optical direct-detected OFDM transmission with Constant Amplitude Zero Auto Correlation Sequence (CAZAC) equalization is experimentally demonstrated with over 15dB power budget. 2.5dB enhancement in sensitivity has been achieved simultaneously with 3dB PAPR suppression.
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| 8. |
- Feng, Z., et al.
(författare)
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Spectrally overlaid DDO-OFDM transmission enabled by optical power division multiplexing
- 2017
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Ingår i: ICOCN 2016 - 2016 15th International Conference on Optical Communications and Networks. - : IEEE. - 9781509034918
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Konferensbidrag (refereegranskat)abstract
- Two 8.3-Gb/s spectrally overlaid DDO-OFDM signals are successfully transmitted along 50-km SMF using optical power division multiplexing and received by a successive interference cancellation (SIC) receiver. Spectral efficiency is doubled with optimized optical modulation index and optical power division ratio.
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| 9. |
- Jiang, Tao, et al.
(författare)
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Investigation of DC-Biased Optical OFDM With Precoding Matrix for Visible Light Communications : Theory, Simulations, and Experiments
- 2018
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Ingår i: IEEE Photonics Journal. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 1943-0655. ; 10:5
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Tidskriftsartikel (refereegranskat)abstract
- Orthogonal frequency-division-multiplexing (OFDM) technology is widely used in visible light communication (VLC) to achieve high data rate transmission. However, the traditional direct-current (DC)-biased optical OFDM (DCO-OFDM) VLC systems suffer from the high peak-to-average power ratio (PAPR) which causes signal clipping distortion, and, thus, performance degradation. Furthermore, severe high-frequency fading due to the limited system bandwidth results in poor bit error rate (BER) performance. Precoding matrix (PM) techniques have been proposed to enhance the performance of VLC OFDM transmission, but a little or no work has been carried out in investigating the theory of PM used in OFDM VLC systems. In this paper, we aim to reveal the theory of PM-DCO-OFDM for a VLC system. To figure out the intrinsic laws of a PM method, we investigate the principles of PAPR reduction, clipping distortion optimization, and signal-to-noise ratio (SNR) distribution equalization. Based on the analysis of PAPR, we theoretically proved the simplicity of PM as a method to reduce the possibility of high PAPR by improving the autocorrelation performance of input symbols. The clipping distortion could be improved due to the reduction of high PAPR. Moreover, the relatively uniform SNR distribution can be achieved by PM through equalizing the clipping and channel noise, which is beneficial to improve the BER performance in high-frequency constrained systems. However, the PM method used in a DCO-OFDM VLC system should consider the transmitting power, modulation format, and transmission distance as a whole to achieve the transmission performance improvement. The simulation results demonstrate the complementary cumulative distribution function of PAPR can be reduced similar to 3 dB, while the performance of clipping distortion power and clipping error probability are significantly improved. Furthermore, experiment is carried out with results showing that the PM method can improve the BER performance in the case that VLC OFDM transmission has enough transmitting power, but with the low transmitting power, the PM also can damage the BER performance. The simulation and experiment results are consistent with our theoretical analysis.
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| 10. |
- Liao, Xiwen, et al.
(författare)
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Comprehensive investigation of key biomarkers and pathways in hepatitis B virus-related hepatocellular carcinoma
- 2019
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Ingår i: Journal of Cancer. - : IVYSPRING INT PUBL. - 1837-9664. ; 10:23, s. 5689-5704
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Our study is aim to explore potential key biomarkers and pathways in hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) using genome-wide expression profile dataset and methods. Methods: Dataset from the GSE14520 is used as the training cohort and The Cancer Genome Atlas dataset as the validation cohort. Differentially expressed genes (DEGs) screening were performed by the limma package. Gene set enrichment analysis (GSEA), weighted gene co-expression network analysis (WGCNA), gene ontology, the Kyoto Encyclopedia of Genes and Genomes, and risk score model were used for pathway and genes identification. Results: GSEA revealed that several pathways and biological processes are associated with hepatocarcinogenesis, such as the cell cycle, DNA repair, and p53 pathway. A total of 160 DEGs were identified. The enriched functions and pathways of the DEGs included toxic substance decomposition and metabolism processes, and the P450 and p53 pathways. Eleven of the DEGs were identified as hub DEGs in the WGCNA. In survival analysis of hub DEGs, high expression of PRC1 and TOP2A were significantly associated with poor clinical outcome of HBV-related HCC, and shown a good performance in HBV-related HCC diagnosis. The prognostic signature consisting of PRC1 and TOP2A also doing well in the prediction of HBV-related HCC prognosis. The diagnostic and prognostic values of PRC1 and TOP2A was confirmed in TCGA HCC patients. Conclusions: Key biomarkers and pathways identified in the present study may enhance the comprehend of the molecular mechanisms underlying hepatocarcinogenesis. Additionally, mRNA expression of PRC1 and TOP2A may serve as potential diagnostic and prognostic biomarkers for HBV-related HCC.
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