一种正交频分复用系统的非线性补偿技术

针对正交频分复用(OFDM)系统在功率放大器(PA)非线性较强时的性能问题,基于一种无线设备非线性与无线信道的联合估计技术,提出了一种基于训练序列的OFDM非线性信道估计与补偿技术.首先基于最小二乘(LS)算法进行发射机非线性与无线信道单位脉冲响应的联合估计,然后依次进行无线信道与发射机非线性的补偿.仿真结果显示,提出方法可逼近不考虑PA非线性时OFDM无线通信系统的完美均衡理论解析值.     

Computationally Efficient Nonlinearity Compensation for Coherent Fiber-Optic Systems

Split-step digital backward propagation (DBP) can be combined with coherent detection to compensate for fiber nonlinear impairments.A large number of DBP steps is usually needed for a long-haul fiber system,and this creates a heavy computational load.In a trade-off between complexity and performance,interchannel nonlinearity can be disregarded in order to simplify the DBP algorithm.The number of steps can also be reduced at the expense of performance.In periodic dispersion-managed long-haul transmission systems,optical waveform distortion is dominated by chromatic dispersion.As a result,the nonlinearity of the optical signal repeats in every dispersion period.Because of this periodic behavior,DBP of many fiber spans can be folded into one span.Using this distance-folded DBP method,the required computation for a transoceanic transmission system with full inline dispersion compensation can be reduced by up to two orders of magnitude with negligible penalty.The folded DBP method can be modified to compensate for nonlinearity in fiber links with non-zero residual dispersion per span.     

内调制光敏管非线性及温度特性的补偿系统

介绍一种在内调制光探测器的基础上采用单片机系统对其输出信号进行收集并处理，构成二次仪表的实现方法。该方法大大地改善了内调制光敏管探测器的非线性及温度特性，且避免了常规硬件补偿的弊端。     

毫米波合成扫频源中的返波管非线性补偿技术

频率锁定是实现毫米波合成式扫频信号源的重要因素,由于返波管振荡器非线性时整机的频率锁定有直接且显著的影响,因此合理地消除返波管振荡器的非线性影响,对实现信号源的功能和关键指标起着极其重要的作用。该文从分析返波管振荡器的非线性产生机理入手,讨论了非线性补偿关键技术,并设计了补偿电路,在实际应用中进行了验证,取得了良好的效果。     

Chromatic Dispersion Compensation of OOK Signals With MLSE Utilizing Diverse VSB Filtering

We present diverse vestigial-sideband-filtering maximum-likelihood sequence estimation (DVSB-MLSE), a modification of MLSE, for residual chromatic dispersion (CD) compensation in nonreturn-to-zero (NRZ) on–off keying (OOK) systems. While VSB filtering can considerably increase residual CD tolerance of MLSE receivers, the performance of MLSE can be further enhanced by diverse reception, through which the MLSE module jointly equalizes samples from upper and lower VSB filtered signals. Simulation results show that compared to conventional MLSE, DVSB-MLSE increases the residual CD tolerance at 3-dB optical signal-to-noise ratio penalty by 110% in a 42.7-Gb/s NRZ-OOK system.      

Nonlinearity and Its Compensation of Semiconductor Laser Diodes for Analog Intensity Modulation Systems

Experimental investigation was carried out on nonlinear video distortions of differential gain and differential phase in various optical transmitters using laser diode structures having a single transverse mode operation. It was observed that the measured nonlinearity of laser diodes was comparable to that of a typical LED. A simple linearizing technique for improving the nonlinearity, using an emphasis principle, is proposed and was experimentally examined, yielding promising results.     

Mitigation of XPM Penalty in 10-Gb/s OOK/DBPSK Mixed Modulation Format 50-GHz-Spaced WDM Transmission by Conversion of OOK to BPSK Using an SOA

Copropagation of return-to-zero differential binary phase-shift keying (RZ-DBPSK) with RZ on–off keying (RZ-OOK) in wavelength-division-multiplexed (WDM) transmission has been found to be detrimental to RZ-DBPSK due to cross-phase modulation (XPM) degradations induced by pattern-dependent RZ-OOK. A method is proposed at the optical cross-connect (not at the transmitter end) to alleviate this degradation, in which the impairing RZ-OOK channel is converted to RZ binary phase-shift keying (RZ-BPSK) in a semiconductor optical amplifier (SOA) prior to 50-GHz-spaced WDM transmission. The data format conversion completely compensates for the XPM degradation, while resulting in an optical signal-to-noise ratio transmission penalty of ${≪}$ 2 dB for converted RZ-BPSK relative to RZ-OOK. Moreover, the wavelength conversion may be used to address contention resolution at the cross-connects.      

内调制微光探测系统的非线性及温度特性的实时补偿

介绍了一种使用新型内调制光电探测器作为探测单元的高精度微光探测系统，利用单片机对系统的模拟信号进行数据采集并处理，极大地改善了内调制微先探测系统的非线性和漫度漂移特性，避免了常规硬件补偿的弊端，提高了系统的测量精度。     

光纤色散补偿后的非线性研究

研究了色散补偿后光纤链路的非线性对脉冲波形及频谱演化的影响。首次得出了非线性薛定谔ＮＬＳ方程的适用于弱或强非线性色散光纤的两种级数解，可分别描述在弱非线性色散光纤中的频谱演化，和在强非线性色散光纤中脉冲波形的演化。首次得出正负色散完全抵消时，适用于任意波形的输出信号的频域表达式、非线性噪声系数、无啁啾高斯脉冲展宽因子表达式和计算结果。     

WDM PON using 10-Gb/s DPSK downstream and re-modulated 10-Gb/s OOK upstream based on SOA

A signal remodulation scheme of 10-Gb/s differential phase-shift keying(DPSK) downstream and 10-Gb/s on-off keying(OOK) upstream using a semiconductor optical amplifier(SOA) and a Mach-Zehnder intensity modulator(MZ-IM) at the optical networking unit(ONU) side for wavelength division multiplexed passive optical network(WDM PON) is proposed.Simulation results indicate that error-free operation can be achieved in a 20-km transmission,and the receiver sensitivity of return-to-zero differential phase-shift keying(RZ-DPSK) is higher than nonreturn-to-zero differential phase-shift keying(NRZ-DPSK) in the proposed scheme.     

一种新型FSK/PSK信号的PSK序列研究

复合调制信号由于其优异的性能,近几年成为许多学者的一个重要研究课题.基于对复合调制信号自相关函数特征的详细理论推导和分析,从高分辨率角度出发,研究了不同PSK调制对FSK/PSK信号分辨率的影响.在未引入旁瓣抑制网络情况下,获得了一种均匀二相编码与Barker码扩展序列组合的新型PSK调制方式,能较大地降低FSK/PSK信号的旁瓣.理论分析和计算机仿真表明:这种新型的复合调制方式可使旁瓣值达到-32.12 dB.这对通信系统、雷达以及信息安全等方面信号调制方式的选取有着重要的参考意义.     

Error Probability Variation Due to the Nonlinearity of the TDMA/PSK Multicarrier System Caused by On-Off Bursting

Representing a satellite transponder as a nonlinear, memoryless, band-limited device, the error probability variation due to on-off transitions of the TDMA signal envelopes in TDMA/PSK multicarrier operation is analyzed. The effects of AM/AM and AM/PM conversion are also taken into account. The results of this study are applied to4phiPSKand8phiPSKsystems, for which the parameters describing the transponder nonlinearity have been taken from the real characteristics obtained by measurements. The numerical calculations show that on-off transitions of the TDMA signal envelopes could cause significant variation of the error probability.     

毫米波合成扫源中扫频非线性补偿技术

在毫米波合成扫源中,扫频状态下的关键指标如扫频精度、扫描时间对测试的精度和效率起着极其重要的作用,要实现较高扫频准确度和快速的扫描就必须解决在扫频状态下非线性的补偿问题,结合实际工作,对某型毫米波合成扫源中扫频非线性产生机理进行了分析,讨论了非线性补偿的关键技术,并设计了补偿电路,在实际工作中进行了验证,取得了良好的效果。     

A WDM-PON with DPSK modulated downstream and OOK modulated upstream signals based on symmetric 10 Gbit/s wavelength reused bidirectional reflective SOA

We investigate a wavelength-division-multiplexing passive optical network (WDM-PON) with centralized lightwave and direct detection. The system is demonstrated for symmetric 10 Gbit/s differential phase-shift keying (DPSK) downstream signals and on-off keying (OOK) upstream signals, respectively. A wavelength reused scheme is employed to carry the upstream data by using a reflective semiconductor optical amplifier (RSOA) as an intensity modulator at the optical network unit (ONU). The constant-intensity property of the DPSK modulation format can keep high extinction ratio (ER) of downstream signal and reduce the crosstalk to the upstream signal. The bit error rate (BER) performance of our scheme shows that the proposed 10 Gbit/s symmetric WDM-PON can achieve error free transmission over 25-km-long fiber transmission with low power penalty.     

Monte Carlo Estimation of PDM-QPSK/OOK and DQPSK/OOK Hybrid Systems Tolerance Against Nonlinear Effects

We compare through Monte Carlo simulations the performance of polarization-division multiplexed quadrature phase-shift keying (PDM-QPSK)/on–off keying (OOK) and differential QPSK (DQPSK)/OOK hybrid systems, taking into account nonlinear phase noise. DQPSK turns out to be better with optimal dispersion-management, while PDM-QPSK proves to be a good candidate for bit rates higher than 40 Gb/s.      

Inverter Nonlinearity Compensation in the Presence of Current Measurement Errors and Switching Device Parameter Uncertainties

This paper proposes a compensation strategy for the unwanted disturbance voltage due to inverter nonlinearity. We employ an emerging learning technique called support vector regression (SVR). SVR constructs a motor dynamic voltage model by a linear combination of the current samples in real time. The model exhibits fast observer dynamics and robustness to observation noise. Then the disturbance voltage is estimated by subtracting the constructed voltage model from the current controller output. The proposed method compensates for all of the inverter nonlinearity factors at the same time. All the processes in estimating distortions are independent of the dead time and power device parameters. From the analysis of the effect on current measurement errors, we confirmed that the sampling error had little negative impact on the proposed estimation method. Experiments demonstrate the superiority of the proposed method in suppressing voltage distortions caused by inverter nonlinearity     

Compensation of Interchannel Crosstalk Induced by Optical Fiber Nonlinearity in Carrier Phase-Locked WDM System

A scheme that compensates the waveform distortion induced by nonlinear interchannel crosstalk such as four-wave mixing (FWM) and cross-phase modulation as well as self-phase modulation in phase-locked wavelength-division-multiplexing transmission systems is proposed. Reduction of FWM-induced waveform distortion by controlling the phase relationship between neighbouring channels and its cancellation by precompensation is successfully demonstrated     

一种适用于UHF频段无源RFID应用的低功耗电源恢复和OOK解调技术

本文提出一种与普通CMOS工艺兼容的、适用于UHF频段无源RFID应用的低功耗电源恢复电路和一种新型OOK解调技术.该解调技术具有结构简单、功耗低、易于集成、适应大动态范围等特点.芯片采用0.18μm CMOS工艺进行设计,测试结果表明在电源电路负载为510kΩ时,恢复出的芯片电源电压为1.6V～2.0V;在发射功率为4WEIRP的条件下,可以在3.7m的距离下正常工作.     

可配置LDPC译码器中低复杂度移位网络的设计

针对可配置LDPC译码器,提出了一种低复杂度的移位网络结构,明显降低了硬件实现的复杂度。基于结构化LDPC译码器的两个特点:输入端的个数是一个常数的倍数、所有移位都是循环移位,提出易于实现且延迟很小的移位网络控制信号生成算法。此外,针对IEEE 802.16e标准的LDPC译码器,设计了采用这种结构的移位电路。基于SMIC 130nm工艺进行仿真,综合结果表明,该电路占用的芯片面积为0.11mm2,最高频率为430MHz。