卫星相干光通信在国外已经接近工程应用阶段,主流的传输接收方式为BPSK调制/零差探测,接收端用光锁相环(OPLL)进行载波恢复。但即使在今天,光锁相环的实现依然有难度,而且存在捕获时间过长等现象。文中借鉴了现在的研究热点技术——光...卫星相干光通信在国外已经接近工程应用阶段,主流的传输接收方式为BPSK调制/零差探测,接收端用光锁相环(OPLL)进行载波恢复。但即使在今天,光锁相环的实现依然有难度,而且存在捕获时间过长等现象。文中借鉴了现在的研究热点技术——光纤通信中的频偏估计、载波相位恢复技术,针对星间激光通信中存在GHz量级大多普勒频移的工程背景,提出了一种基于DSP的频偏开环补偿算法。从理论上分析了该算法的原理,重点研究了激光器噪声和接收机噪声对频偏估计精度带来的影响,并通过仿真进行了验证。本振光功率为10 d Bm时,当接收功率高于-47 d Bm,误码率优于10-4;将接收功率提高10 d B后,频偏估计标准差小于370 k Hz。展开更多
To detect higher order polynomial phase signals （HOPPSs）, the smoothed-pseudo polynomial Wigner-Ville distribution （SP-PVCVD）, an improved version of the polynomial Wigner-Ville distribution （PVCVD）, is presente...To detect higher order polynomial phase signals （HOPPSs）, the smoothed-pseudo polynomial Wigner-Ville distribution （SP-PVCVD）, an improved version of the polynomial Wigner-Ville distribution （PVCVD）, is presented using a separable kernel. By adjusting the lengths of the functions in the kernel, the balance between resolution retaining and interference suppressing can be adjusted conveniently. The proposed method with merits of interference terms reduction and noise suppression can provide time frequency representation of better readability and more accurate instantaneous frequency （IF） estimation with higher order SP-PVfVD. The performance of the SP-PWVD is verified by computer simulations.展开更多
We experimentally demonstrate a direct-detection orthogonal-frequency-division-multiplexing quadraturephase-shift-keying（OFDM-QPSK） system that is capable of delivering a 32 Gbaud OFDM-QPSK signal over7 km single-mo...We experimentally demonstrate a direct-detection orthogonal-frequency-division-multiplexing quadraturephase-shift-keying（OFDM-QPSK） system that is capable of delivering a 32 Gbaud OFDM-QPSK signal over7 km single-mode fiber-28（SMF-28）. Intra-symbol frequency-domain averaging（ISFA） channel response estimation is applied to suppress in-band noise,while discrete Fourier transform-spread（DFT-spread） is used to reduce the peak-to-average power ratio（PAPR） of the transmitted OFDM signal. With the aid of ISFA-based channel estimation and PAPR reduction enabled by DFT-spread,the bit-error ratio of the system after 7 km SMF-28 transmission can be improved from 2×10^-3 to error-free when the received optical power is -8.5 d Bm.展开更多
A data-aided method of joint frequency offset and chromatic dispersion estimation based on the Chu training sequences is shown in 112 Gb/s polarization-multiplexed （PM） quadrature phase-shift keying and 224 Gb/s PM-...A data-aided method of joint frequency offset and chromatic dispersion estimation based on the Chu training sequences is shown in 112 Gb/s polarization-multiplexed （PM） quadrature phase-shift keying and 224 Gb/s PM-16-quadrature amplitude modulation with different pulse-shaping filters, respectively. The proposed method achieves a good accuracy and is verified to be robust to polarization mode dispersion.展开更多
文摘卫星相干光通信在国外已经接近工程应用阶段,主流的传输接收方式为BPSK调制/零差探测,接收端用光锁相环(OPLL)进行载波恢复。但即使在今天,光锁相环的实现依然有难度,而且存在捕获时间过长等现象。文中借鉴了现在的研究热点技术——光纤通信中的频偏估计、载波相位恢复技术,针对星间激光通信中存在GHz量级大多普勒频移的工程背景,提出了一种基于DSP的频偏开环补偿算法。从理论上分析了该算法的原理,重点研究了激光器噪声和接收机噪声对频偏估计精度带来的影响,并通过仿真进行了验证。本振光功率为10 d Bm时,当接收功率高于-47 d Bm,误码率优于10-4;将接收功率提高10 d B后,频偏估计标准差小于370 k Hz。
基金supported partly by the Program for New Century Excellent Talents in University, Ministry of Education,China(NCET-05-0803)supported by Information Controlling Technology of Communication System National Key Laboratory(9140C1301020801).
文摘To detect higher order polynomial phase signals （HOPPSs）, the smoothed-pseudo polynomial Wigner-Ville distribution （SP-PVCVD）, an improved version of the polynomial Wigner-Ville distribution （PVCVD）, is presented using a separable kernel. By adjusting the lengths of the functions in the kernel, the balance between resolution retaining and interference suppressing can be adjusted conveniently. The proposed method with merits of interference terms reduction and noise suppression can provide time frequency representation of better readability and more accurate instantaneous frequency （IF） estimation with higher order SP-PVfVD. The performance of the SP-PWVD is verified by computer simulations.
文摘We experimentally demonstrate a direct-detection orthogonal-frequency-division-multiplexing quadraturephase-shift-keying（OFDM-QPSK） system that is capable of delivering a 32 Gbaud OFDM-QPSK signal over7 km single-mode fiber-28（SMF-28）. Intra-symbol frequency-domain averaging（ISFA） channel response estimation is applied to suppress in-band noise,while discrete Fourier transform-spread（DFT-spread） is used to reduce the peak-to-average power ratio（PAPR） of the transmitted OFDM signal. With the aid of ISFA-based channel estimation and PAPR reduction enabled by DFT-spread,the bit-error ratio of the system after 7 km SMF-28 transmission can be improved from 2×10^-3 to error-free when the received optical power is -8.5 d Bm.
基金supported by the National Natural Science Foundation of China(No.61205065)the National "863" Project of China(No.2013AA013401)the Open Fund of State Key Laboratory of optical fiber communication network with the new type of optical communication system(Shanghai Jiao Tong University)(No.2013GZKF031310)
文摘A data-aided method of joint frequency offset and chromatic dispersion estimation based on the Chu training sequences is shown in 112 Gb/s polarization-multiplexed （PM） quadrature phase-shift keying and 224 Gb/s PM-16-quadrature amplitude modulation with different pulse-shaping filters, respectively. The proposed method achieves a good accuracy and is verified to be robust to polarization mode dispersion.
