Review of Glass and Polymer Multimode Fibers Used in a Wimedia Ultrawideband MB-OFDM Radio Over Fiber System

In this paper, we have exhibited the potential of the glass- and polymer-based multimode fibers to be used in a radio over fiber (RoF) system in order to extend the indoor coverage of the Wimedia multiband orthogonal frequency division multiplexing (MB-OFDM) ultrawideband (UWB) standard. After the design of a test setup operating at 850 nm, we have performed the physical characterization of the RoF system especially the mask test compliance, the error vector magnitude (EVM), or the relative constellation error (RCE) variation as a function of the system parameters [radio frequency (RF) power, optical attenuation, fiber length, laser bias current]. The transmission performance of both 200 and 480-Mb/s Wimedia signals is demonstrated through a 100-m link length of glass- and polymer-based multimode fibers: transmission penalties are quantified by RCE with values under the standard requirements. Two different behaviors depending on the core material of the fiber have been identified in this study.      

Methods for Ultra-Wideband Pulse Generation Based on Optical Cross-Polarization Modulation

Optical methods for different type ultra-wideband (UWB) pulse generation based on cross-polarization modulation (CPM) are proposed and demonstrated in this paper. Two polarity-reverse pulses can be obtained by CPM and birefringence time delay to form a monocycle pulse. A semiconductor optical amplifier (SOA) is placed after the monocycle pulse process for doublet pulse generation. These two kinds of pulses can be employed in single-band impulse radio UWB (IR-UWB) systems. Two kinds of multi-band UWB pulses can be generated based on monocycle pulse train with proper apodization profiles, realized by hybrid photonic microwave filter and synchronous polarization modulation respectively. Experimental results show that these pulses can be used in multi-band UWB (MB-UWB) over fiber systems.      

An approach to ultrawideband pulse generation and distribution over optical fiber

We propose a novel approach to generating and distributing ultrawideband (UWB) pulse signals over optical fiber. The proposed system consists of a single-wavelength laser source, an electrooptic phase modulator (EOPM), a length of single-mode fiber (SMF), and a photodetector (PD). The combination of the EOPM, the SMF link, and the PD forms an all-optical microwave bandpass filter, which is used to generate a UWB signal with a spectrum meeting the regulation of the Federal Communication Commission. Gaussian doublet pulses are obtained at the receiver front-end, which can provide several gigahertz bandwidths for applications in high-bit-rate UWB wireless communications. Experimental results measured in both temporal and frequency domains are presented.     

A 24-GHz Ultra-Wideband Over Fiber System Using Photonic Generation and Frequency Up-Conversion

We propose and experimentally demonstrate the generation of baseband ultra-wideband (UWB) monocycle and doublet pulses using one dual-parallel Mach–Zehnder modulator. We further present a proof-of-concept demonstration of a 24-GHz UWB over fiber system based on frequency up-conversion. The performance of the up-converted UWB pulses after fiber transmission is studied.      

Experimental Demonstration of All-Optical 781.25-Mb/s Binary Phase-Coded UWB Signal Generation and Transmission

In this letter, an all-optical incoherent scheme for generation of binary phase-coded ultra-wideband (UWB) impulse radio signals is proposed. The generated UWB pulses utilize relaxation oscillations of an optically injected distributed feedback laser that are binary phase encoded (0 and $pi$) and meet the requirements of Federal Communications Commission regulations. We experimentally demonstrated a 781.25-Mb/s UWB-over-fiber transmission system. A digital-signal-processing-based receiver is employed to calculate the bit-error rate. Our proposed system has potential application in future high-speed UWB impulse radio over optical fiber access networks.      

All-Fiber Ultrawideband Pulse Generation Based on Spectral Shaping and Dispersion-Induced Frequency-to-Time Conversion

An approach to generating and distributing ultrawideband (UWB) pulses based on optical spectral shaping and frequency-to-time conversion using all-fiber components is proposed and demonstrated. In the system, the spectrum of an ultrashort pulse from a mode-locked fiber laser is spectrally shaped by an all-fiber spectrum shaper, to produce a monocycle- or a doublet-shaped power spectrum. Thanks to the frequency-to-time conversion in a dispersive fiber, time-domain optical pulses exhibiting the user-defined shape of the optical power spectrum are obtained. Experiments based on the proposed approach are carried out. UWB monocycle or doublet pulses are generated     

10MHz?4GHz 超宽带微波光电子系统设计

为了改善高频微波进行长距离传输时具有很大的损耗,频率向高频扩展受限的特性。本文基于微波信号光纤 传输 （RoF）技术,采用波长为1550nm 的多量子阱分布式反馈激光器和数据速率高达10Gbps 的数字式PIN 光电探测 器,设计了一款工作频率为10MHz~4GHz 的超宽带微波光电子系统。在整个频率范围内满足了8dB 增益,增益平坦度 ? 1.5dB 及输入/输出驻波比＜2 的指标要求,符合工程需要,实现了数字式光电子器件在模拟通信中的应用,具有广泛 的应用范围。     

基于光纤光栅的超宽带信号产生与传输

针对现有方法功率利用率低与调制实现困难的问题,采用基于光纤光栅（FBG）的超宽带（UWB）调制信号产生方法,建立了UWB信号产生系统。不仅可以实现UWB信号的调制,而且提高了产生信号的信噪比。实现了二进制相位调制（BPM）、脉冲幅度调制（PAM）和脉冲位置调制（PPM）等UWB信号产生。分析了光纤传输对产生信号的影响,...     

Impact of Mach-Zehnder Modulator Chirp on Radio over Fiber Links

The impact of Mach-Zehnder modulator (MZM) chirp on single sideband (SSB) and carrier suppressed double sideband (CS-DSB) modulation radio over fiber (RoF) links are investigated and simulated. Finite extinction ratio and drive signal unbalanced ratio of non-ideal MZM are considered, power variation of target microwave signal and harmonic suppression are calculated and evaluated. Our results suggest that unbalanced ratio could be optimized to minimized the power variation owing to the finite extinction ratio and improve the harmonic suppress ratio in the two kinds of RoF links. However, harmonic suppression ratio declined rapidly with the decrease of extinction ratio in the CS-DSB RoF link. For a non-ideal modulator with low extinction ratio, high quality microwave signal could be obtained in the SSB RoF link while an additional filter is required to suppress the unwanted harmonic components in the CS-DSB RoF link.     

An IR-UWB Photonic Distribution System

Experimental results are presented for a novel distribution system for an impulse radio ultra-wideband (UWB) radio signals employing a gain-switched laser. The pulse position modulated short optical pulses with a bit rate of 1.25 Gb/s are transmitted over fiber to a remote antenna unit, where the signal is converted to the electrical domain and undergoes spectral shaping to remove unwanted components according to UWB requirements. An experimental radio terminal has also been constructed to enable bit-error-rate measurements to be carried out. These experiments show that the optical distribution system will be capable of supporting the radio part of the system.      

Converged delivery of WiMAX and wireline services over an extended reach passive optical access network

In this paper we present long-reach fiber access links supporting transmission of Worldwide Interoperability for Microwave Access (WiMAX) compliant signals. We present bi-directional full-duplex transmission of 256-state quadrature amplitude modulation (256-QAM) modulated WiMAX-compliant signals on a 2.4-GHz RF carrier over an 80-km long-reach access link at 100 Mb/s (down) and 64 Mb/s (up). Transmission of 64-QAM and 256-QAM-modulated signals on a 5.8-GHz RF carrier over a 118.8-km access link converged with four baseband differential quadrature phase shift keying (DQPSK) modulated wireline channels, along with ultra-wide band (UWB) and phase shift keying (PSK) radio-over-fiber (RoF) wireless signals over a deployed optical fiber link is also presented.     

Comparison of planar dipoles in UWB applications

The characteristics of four planar dipoles are studied and compared based on the design considerations of ultrawide-band (UWB) antennas. Their impedance matching, realized gain, and polarization over the UWB band are investigated. The current distributions on the dipoles are illustrated to interpret their different radiation characteristics. Furthermore, pulses radiated in different directions are presented for both single-band and multiband schemes in UWB applications.     

Multi-band QPSK signal transmission implemented with remote up-conversion and Schottky RF detectors in a 60-GHz millimeter wave radio-over-fiber system

A simple multi-band QPSK signal transmission scheme, constructed by using an optical remote up-conversion technique and a Schottky diode RF detector, is theoretically analyzed and experimentally implemented in a 60-GHz millimeter wave (mm-wave) radio over fiber (RoF) system, for the first time. There is no need for complex system architecture or any expensive high-frequency clock source in our scheme. Simulation results show that our scheme is highly tolerant to fiber dispersion, compared with the conventional 60 GHz multi-band RoF system. In the experimental demonstration, successful delivery of QPSK signals at two 60-GHz sub-bands is achieved over 50-km fiber and 4-m wireless distance.     

基于SOA—XGM的超宽带脉冲信号的光学产生法

超宽带技术（UWB）在无线通信、雷达、传感等多个领域有着重要的应用,由低损耗、高带宽的光纤传输的UWB光传输系统,即UWB over fiber,是目前国内外研究的热点课题,如何在光域中生成UWB信号是该系统的关键技术之一。为此提出了一种利用半导体光放大器（SOA）的交叉增益调制（XGM）效应和布拉格光纤光栅（FBG）...     

有线无线混合接入RoF系统结构分析与验证

随着用户需求的不断增加,能提供有线无线混合接入的光纤无线(RoF)系统成为了新的研究热点.在分析比较国内外混合接入技术的基础上,设计了一种波长交织(WI)密集波分复用( DWDM)的全双工混合接入RoF系统,实验仿真初步证实了该系统的有效性.     

Full-Duplex 60-GHz RoF System With Optical Local Oscillating Carrier Distribution Scheme Based on FWM Effect in SOA

A full-duplex 60-GHz radio-over-fiber (RoF) system using novel optical local oscillating (LO) carrier distribution scheme to reduce the system cost and realize centralized management is proposed and experimentally demonstrated. In the proposed scheme, the optical LO carriers for producing remote electrical LO signals at the base stations (BSs) are generated together with the downlink RoF carriers at the central station (CS) via four-wave-mixing effect in semiconductor optical amplifier, and are then distributed to the BSs along with the downlink RoF signals. By down-converting the 60-GHz-band uplink signal with the remotely produced 60-GHz LO signal and reusing the optical LO carriers as the uplink optical source, only a cost-effective intermediate frequency modulator is required at each BS to transmit the uplink signal, which will dramatically reduce the whole system budget due to a large amount of BSs. Moreover, the operating frequency of each BS can be controlled remotely at the CS end to realize centralized management and convenient reconfiguration. Using the proposed scheme, 622-Mb/s signals for both directions are successfully transmitted over a 20-km single-mode fiber link and a 50-cm wireless channel with less than 0.1- and 0.2-dB power penalty for downlink and uplink, respectively.      

Multiple ultra-wideband signal sources exploiting XPM in SFRL

A novel scheme for all-optical broadcast ultra-wideband (UWB) monocycle pulses generation based on cross-phase modulation (XPM) in semiconductor fiber ring laser (SFRL) is proposed, in which three UWB positive or negative monocycle pulses can be generated simultaneously. A comprehensive broad-band dynamic model for this kind of all-optical broadcast UWB monocycle sources is established, which is further applied to numerically analyze the impacts of injection current of semiconductor optical amplifier (SOA), the power and wavelength of the signal light on the performance of the UWB positive monocycle pulses with higher power spectral density. The results show that the spectra of the UWB positive and negative monocycle pulses generated by this scheme match the Federal Communications Commission (FCC) definition quite well. Three UWB positive monocycle pulses with better performance can be obtained when the power of signal light is at a high level, and three other UWB positive monocycle pulses with good tolerance to both the injection current of the SOA and the wavelength of the signal light can be obtained. In addition, the powers of the lasing light coupled into the SFRL should not be strong to obtain three UWB positive monocycle pulses with better performance.     

基于双平行PM调制的60GHz光毫米波RoF系统研究

提出了一种采用相位调制器产生六倍频光载毫米波的RoF系统。该系统使用一个双平行相位调制器实现六倍频的调制,通过调节相位调制器的相位偏移量,产生出抑制一阶边带的光谱,耦合相减后得到三阶边带信号,在光电检测器中拍频,产生六倍于射频信号的光载毫米波。仿真结果表明,10GHz射频信号可以产生60GHz光载毫米波信号,5Gb/s的数据信号可在单模光纤中传输10km以上。     

基于相位调制器产生光毫米波的全双工光纤无线通信系统

提出并实验研究了一种基于相位调制器产生光毫米波信号的全双工光纤无线通信(RoF)系统。在中心站采用相位调制器结合滤波的方法产生重复频率为40GHz的载波抑制双边带毫米波信号,利用交叉复用器分离开毫米波信号的上下边带,其中的一个边带强度调制数据速率为2.5Gbit/s的下行基带信号,另一个边带被发送到基站调制上行传输的基带数据。该系统抗色散效果好,在经过40km标准单模光纤上/下行传输数据速率2.5Gbit/s的基带信号后,双向的传输功率代价都小于0.5dBm。在光纤无线通信系统中采用相位调制器结合滤波的方法产生光毫米波,同时基于波长重用技术再生上行光载波信号,可以简化中心站和基站配置,节约系统成本。     

Ultra wideband over fibre transparent architecture for high-bit-rate home networks

Bandwidth hungry services are developing rapidly in home networking and needs for gigabit home networks will appear shortly, following the introduction of gigabit optical access networks. In addition, ubiquitous wireless connectivity is required by users to connect multiple multimedia devices inside the home. Some wireless standards, such as ultra wideband (UWB), are able to provide Gbps data rate but with a limited coverage. To extend the coverage of this system to the scale of the house, some possible architectures are presented. Among them, we focus on a multipoint-to-multipoint (MP2MP) radio-over-fibre (RoF) architecture based on a N?×?N optical splitter that is very promising. The UWB MAC layer is able to control the system and no optical MAC layer is required, so that the optical path becomes a “transparent tunnel”. Simulations and experimental investigations demonstrate the technical feasibility of this innovative MP2MP RoF architecture.