RoF系统中抑制马赫曾德尔调制器非线性的研究

为了降低MZM对模拟信号产生的非线性影响,提出了一种基于RoF系统的以三角波作为副载波的信号传输方案.该方案采用线性度高的三角波携带基带数据并经过MZM调制.调制后的光信号可以在RoF系统的接收端通过直接检测得到余弦形式射频信号,该射频信号几乎不存在由于MZM的非线性调制引起的边带分量.仿真分析了在直接调制和间接调制的...     

OFDM系统中考虑信源编码特性的多播资源分配方案

针对OFDM系统单播以及传统多播没有充分发挥无线传播开放性优势的问题,提出了多个多播组保证组间比例公平的资源分配方案.该方案由子载波分配算法及功率分配算法构成,前者通过修正存在的单播子载波分配算法得到;后者基于理论推导的非线性方程组,得到了子载波分配给定条件下的最优功率分配.仿真结果显示,所提方案能够确保完美的多播组间公平性,且和速率容量性能明显优于传统多播方式.结合方案的低复杂度特性,它适合在实际无线系统的音/视频多播中进行应用.     

ROF传输系统的研究及应用

针对射频信号在光缆中传输存在衰减大、易受干扰、保密性差等缺点,本文提出了一种新的方案,该方案首先将射频信号调制到光载波上,从而借助光载波实现射频信号的光传输.光纤传输与电缆传输相比,具有衰减小、频带宽、抗干扰性强、安全性能高、体积小、重量轻等优点,因此在长距离传输和特殊环境等方面具有无法比拟的优势.     

Chirped AM激光雷达中线性调频信号的产生

线性调频强度调制(Chirped AM)激光雷达将微波雷达中调频测距原理巧妙地应用于激光雷达,用一个线性调频的射频副载波调制激光输出强度.介绍了FM测距的基本数学原理,及激光雷达系统的基本构成和工作原理.在分析对比本体制激光雷达中一项关键技术一一线性调频信号产生几种实现方法的基础上,依据直接数字频率合成和正交调制技术,提出了一种宽带线性调频信号产生方案.介绍了信号发生系统的基本结构以及工作原理,探讨了系统实现的关键技术、技术难点及改进办法.     

用MATLAB实现GMSK信号的产生与解调

采用正交调制的方法,在MATLAB环境下用Simulink组件产生了射频GMSK信号。编写m文件实现1bit差分解调算法,对产生的信号进行解调,得到较好的结果。为验证该算法的正确性,还采集了信号源的射频GMSK信号数据,在已知采样速率、信息码速率的条件下进行解调,针对采样起始时刻的不确定性,还添加了判断信息数据跳变时刻的代码,也取得了满意的解调效果,说明该算法具有一定的实用性。     

基于数字正交方式实现的一种GMSK调制

从GMSK调制原理出发,分析了GMSK信号的特征,依据正交调制理论,由CPM调制的公式推导出GMSK调制的载波相位和正交I、Q分量运算公式,并提出以DSP、FPGA、DUC为平台的GMSK调制算法实现方案.文中方案成功用于某测试仪项目,根据用户需求选择码元类型、码元速率、BTb值、载波频率等参数实现了GMSK调制信号的产生.     

雷达高度表回波模拟信号的矢量合成技术

介绍了一种采用正交调制矢量合成技术产生雷达信号的方法和原理，同时对该方法可能存在镜像假目标和载波泄漏的原因进行了分析，给出了对其基带信号的预失真补偿方法；文中还介绍了利用该技术产生相参ＰＣＰＤ雷达高度表回波模拟信号的技术方案。     

一种集成无线和有线信号的混合接入系统研究

为了满足不同高带宽业务的需求,提出一种同时传输有线和无线信号的混合接入网系统。在下行链路中,无线信号以相位调制格式在光载波上传输,有线信号以强度调制格式重调制在光载波上,在ONU(光网络单元)采用不同的解调方案进行解调接收;在上行链路中,通过载波重用技术再调制有线基带信号并将其传输至OLT(光线路终端),简化了系统的器件配置。利用光学软件Optisystem验证了系统的可靠性和有效性。仿真结果显示,无线链路信号和有线基带信号经过正交调制传输后,在用户端仍能得到较好效果的眼图,说明它们能被准确地接收。采用载波重用技术的上行基带信号也能被OLT准确地接收。     

低成本直接射频正交调制无线发射机的新设计

提出了现场可编程门阵列(FPGA)直接射频正交调制无线通信发射机的一种新设计。新设计克服了传统正交调制方案结构复杂的缺点,去掉了传统正交调制方案中的基带数字处理芯片和射频部分之间的数模转换器件和混频器,使基带数字处理芯片和射频正交调制器直接连接,最大化地实现了传统无线通信发射机的软件化和数字化。采用新技术制作的无线发射系统的实测表明,新发射机误码率达到了传统的正交调制方案的误码水平。新设计不需要传统方案必须的数模转换器件和混频器,使系统简化,成本降低。     

通用OFDM信号分析方案

各种不同的OFDM系统可以通过导频子载波的位置和数据载波的调制方式来区分。文章提出了一种通用OFDM信号分析解决方案。这类信号的处理链路通常包括:同步、参数估计和测量模块,一般使用最大似然(MaximumLikelihood)和最小均方误差MMSE估计方法以获得最佳测量精度。该方案还提供多种分析结果,能更加深入研究射频和基带信号的调制质量。     

基于差分相位再调制与时延干涉检测的WDM-PON辅助管理和控制通道实现方法

波分复用无源光网络（wavelength-division multiplexed passive optical network,WDM-PON）中,操作管理和维护数据路径与用户数据路径在传输汇聚层是彼此独立的。操作管理和维护数据可以通过透传和码传两种方式进行发送。其中,透传方式由于无需额外的转码器件以及具有低时延等特性被广泛应用于各种行业网络。不同于现有的透传模式,即基带再调制和射频通道,提出了一种新型的基于差分相位再调制与时延干涉检测的辅助管理和控制通道实现方法。所提方法的辅助管理和控制信号以相位参数再调制于用户信号之上,而用户信号采用传统强度调制,因此辅助管理和控制信号的再调制过程将不会对用户信号质量产生影响。相对地,基带再调制和射频通道都会对用户信号造成扰动,这在抖动要求较高的行业网内是不允许的。所提方法被认为是波分复用无源光网络中一种有效的辅助管理和控制通道的实现方法。     

Centralized light-wave WDM-PON employing DQPSK downstream and 00K remodulated upstream signals

A novel architecture for wavelength-division-multiplexing passive optical network (WDM-PON) with centralized light-wave is proposed and demonstrated. At the optical line terminal (OLT) session of this architecture, optical differential quadrature phase shift keying (DQPSK) modulated signal with constant-intensity at 10 Gbit/s is utilized for downstream transmission. At the optical network unit (ONU), part of the downstream optical power is remodulated with on-off keying (OOK) intensity modulation at 10 Gbit/s for upstream without additional laser. Simulation results show that the power penalties of the downstream for 20 km single-mode fiber (SMF) transmission and multi-channels are negligible. While for the upstream, the power penalties are obvious. The simulation results and analysis also reflect that by reducing the launch power of DQPSK transmitters, power penalties can be reduced, although the transmission distance is limited.     

Multicast-enabled high-speed VCSEL technology for flexible data center networks

We experimentally demonstrate the multiple signal modulation on a single class 10 G vertical cavity surface emitting laser (VCSEL) carrier at 1 310 nm for next generation multicast-enabled data center networks. A 10 Gbit/s data signal is directly modulated onto a single mode VCSEL carrier. To maximize carrier spectral efficiency, a 2 GHz reference frequency (RF) clock tone is simultaneously modulated on the VCSEL phase attribute. The inherent VCSEL orthogonal polarization bistability with changing bias current is further exploited in transmission of a polarization based pulse per second (PPS) timing clock signal. Therefore, we simultaneously transmit a 10 Gbit/s directly modulated data, 2 GHz phase modulated RF and a polarization-based PPS clock signals using a single mode 10 GHz bandwidth VCSEL carrier. It is the first time that a single class 10 G VCSEL carrier is reported to transmit a directly modulated data, phase modulated RF clock and polarization based PPS timing signal simultaneously in a single wavelength. A of G.652 single mode fibre (SMF) transmission over 3.21 km is experimentally attained. A receiver sensitivity of ?15.60 dBm is experimentally obtained for the directly modulated 10 Gbit/s data signal. A 3.21-km-long SMF transmission introduces a penalty of 0.23 dB to the data signal. The contribution of a 2 GHz phase modulated RF and a polarization-based PPS clock signal to this penalty is found to be 0.03 dB. An RF single-side band (SSB) phase noise values of ?82.36 dBc/Hz and ?77.97 dBc/Hz are attained without and with simultaneous directly modulated data and polarization-based PPS clock signals respectively for a 3.21-km-long SMF transmission. This work provides an alternative efficient and cost effective technique for simultaneous high-speed multiple information transmission to different network nodes within a data center network through shared network infrastructure.     

Centralized light-wave WDM-PON employing DQPSK downstream and OOK remodulated upstream signals

A novel architecture for wavelength-division-multiplexing passive optical network(WDM-PON)with centralized light-wave is proposed and demonstrated.At the optical line terminal(OLT)session of this architecture,optical differential quadrature phase shift keying(DQPSK)modulated signal with constant-intensity at 10 Gbit/s is utilized for downstream transmission.At the optical network unit(ONU),part of the downstream optical power is remodulated with on-off keying(OOK)intensity modulation at 10 Gbit/s for upstream without additional laser.Simulation results show that the power penalties of the downstream for 20 km single-mode fiber(SMF)transmission and multi-channels are negligible.While for the upstream,the power penalties are obvious.The simulation results and analysis also reflect that by reducing the launch power of DQPSK transmitters,power penalties can be reduced,although the transmission distance is limited.     

Hybrid Access Network Integrated With Wireless Multilevel Vector and Wired Baseband Signals Using Frequency Doubling and No Optical Filtering

This letter experimentally demonstrated a hybrid access network which supports both radio-over-fiber and fiber-to-the-x systems. A 20-GHz radio-frequency (RF) 312.5-MSymbol/s M-ary phase-shift keying (PSK) signal and a baseband (BB) 1.25-Gb/s on–off keying signal are simultaneously generated and transmitted over an identical distributed infrastructure. The wired BB signal is compatible with the existing passive optical network (PON) system, and the wireless RF PSK signal can also share the same distributed infrastructure. The proposed system has no RF fading issue, no narrowband optical filter at remote node to separate the RF and BB signals, and can carry vector signals. Moreover, a frequency doubling for optical RF signal generation is achieved to reduce the bandwidth requirement of the transmitter. After transmission over 25-km standard signal-mode fiber, the receiver sensitivity penalties are less than 0.5 dB for both the RF and BB channels.      

Application of optical frequency comb generation with controlled delay circuit for managing the high capacity network system

The generation of optical frequency comb (OFC) with novel controlled delay circuit is presented in this study. The proposed OFC is based on a single laser source which is cascadingly connected with three modulators; all the modulators are tailored by RF signal while incorporating no phase shifter or electrical/optical amplifier. The proposed OFC is used as a source at optical line terminal (OLT) of WDM-PON setup, which serves multiple users with a single laser source making OLT side very cost effective. 41 comb lines with over 40 dB tone to noise ratio and high side mode suppression ratio, least amplitude difference of under 0.3 dB, with cost effective setup is an attractive source for WDM-PON system. The frequency spacing is 32 GHz between OFCG lines which provides enough bandwidth for data transmission, the overall bandwidth provided by this scheme is 1.2 THz. Using DPSK modulation technique across each frequency of OFCG, the controlled delay circuit increases the capacity by factor two, whereas by deploying DQPSK modulation technique, it quadrupled the overall capacity in downlink transmission. Thus, the system offers four times increased capacity ∼1.6 Tbps by deploying state of the art technique for modulation and generating OFC with controlled delay. The average power penalty in the downlink and uplink transmission is 2.5 dBm and 3.13 dBm.     

Cost-Effective Multiservices Hybrid Access Networks With no Optical Filter at Remote Nodes

This letter experimentally demonstrates a multiservices hybrid access network integrated radio-over-fiber and fiber-to-the-home systems which share the same distributed architecture. A 1.25-Gb/s baseband signal and a 14.375-GHz radio-frequency (RF) signal with 625-Mb/s binary phase-shift keying data are generated and transmitted employing a commercially available dual-electrode Mach-Zehnder modulator. The proposed scheme offers better performance, has no RF fading issue, can carry vector signals, and requires no optical filter at remote nodes. After transmission over 25-km single-mode fiber, the proposed scheme successfully achieves less than 0.5-dB sensitivity penalties.     

Cognitive radio network with continuous energy‐harvesting

In this paper, the performance of a cooperative cognitive radio (CR) network is investigated under continuous energy harvesting scenario. A CR node harvests energy from both the sources: non‐radio frequency (RF) signal (ambient sources) or from RF signal (primary user signal). It harvests from non‐RF signal during sensing time of its detection cycle, and from both the sources, RF signal and non‐RF signal, during transmission time as per sensing decision. Several novel analytical expressions are developed to indicate the harvested energy, energy reward, energy cost in a detection frame, and throughput. The performance of the CR network is investigated to maximize the throughput considering energy causality constraints and collision constraints. Analytical results are validated through extensive simulation results. Copyright © 2016 John Wiley & Sons, Ltd.     

WDM—PON在未来接入网中的应用

通过对WDM—PON与传统xPON技术的比较,结合分析全业务环境下接入网的发展趋势,论述了WDM—PON技术及其在未来接入网中的应用前景。     

基于深度学习的蓝牙射频指纹识别系统

蓝牙射频指纹具有难以伪造的优点，基于射频指纹的身份识别能有效提高网络的安全性。文中设计了一种基于深度学习网络的蓝牙射频指纹识别系统。首先，利用Hackrf One软件无线电平台和GNU Radio软件在蓝牙信号广播阶段采集多种蓝牙信标信号。其次，对蓝牙信号进行预处理，将预处理后的数据分为训练集与验证集。然后，使用MATLAB深度学习工具箱来设计长短期记忆网，利用训练数据集对各个网络进行训练，得到蓝牙射频指纹识别网络。最后，利用验证集对上述网络进行测试和分析。当迭代次数为300时，网络对3种蓝牙信标的射频指纹识别的准确率均达到80%以上。