60-GHz Photonic Millimeter-Wave Link for Short- to Medium-Range Wireless Transmission Up to 12.5 Gb/s

In this paper, a 60-GHz photonic millimeter-wave link system for short- to medium-range broadband wireless data transmission is investigated. The system employs advanced mm-wave photonic components and radio-over-fiber (RoF) techniques for the generation of a DSB-SC optical mm-wave carrier and its subsequent on-off-keying modulation and transmission. For short-range applications, we have constructed a compact wireless RoF transmitter consisting of a high-frequency photodiode and a mm-wave antenna only. This system achieved error-free ($hbox {BER}=10^{-9}$, $2^{31}-1$ PRBS, NRZ) in-door transmission of 12.5-Gb/s signals over wireless distances up to 3.1 m with a receiver sensitivity as low as $-$ 45.4 dBm . For fixed wireless access (FWA) requiring a bit error rate of $10^{-4}$, the maximum transmission distance for 12.5 Gb/s is increased up to 5.8 m. For medium-range broadband wireless transmission an electrical radio-frequency (RF) amplifier was employed in the RoF transmitter. Here we achieved 7.5-Gb/s error-free transmission in out-door line-of-sight experiments over wireless distances of up to 36 m. Based upon the experimental results, we expect that the maximum wireless distance the system could accommodate for 12.5 Gb/s is in the kilometer range when using high-gain antennas and an RF transmitter amplifier with a sufficient bandwidth.      

System-on-Packaging with Electroabsorption Modulator for a 60-GHz Band Radio-Over-Fiber Link

A system-on-packaging (SoP) with an electroabsorption modulator (EAM) for a 60 GHz band radio-over-fiber (RoF) link is described. The system consists of an EAM device, a microstrip filter, and a low noise amplifier (LNA). The microstrip filter was used to achieve impedance matching between the EAM device and the LNA and to reject the local oscillator (LO) frequency of the heterodyne system. The frequency response and the effect of the EAM bias voltage were measured for a simple RF/optical link. A 60 GHz band RoF link with 2.5 GHz intermediate frequency (IF) was prepared to measure the transmission characteristics of the 16 QAM data.     

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.     

基于超长分布式2阶喇曼放大器的光载射频传输

为了提升光载射频传输链路的链路增益以及传输距离,采用了L波段的超长分布式2阶喇曼放大器结构对光信号进行放大。从理论上对分布式2阶喇曼放大器以及光载射频传输链路的原理进行了解释,利用信号光、1阶抽运光、2阶抽运光以及噪声之间的耦合方程组分析了它们之间的关系,并且得到了基于超长分布式2阶喇曼放大器的光载射频传输系统的1阶射频信号增益。通过数值仿真以及系统实验得到了抽运功率大小对超长分布式2阶喇曼放大器的开关增益的影响、光载射频传输系统在0GHz~7GHz范围内的频率响应及其射频增益以及该光载射频传输链路在应用超长分布式2阶喇曼放大器后的相位噪声情况。结果表明,光载射频传输在超长分布式2阶喇曼放大器的作用下获得了28.1dB的链路增益,在距离为80.94km的光链路上实现了近似无损传输,射频信号开关增益与射频信号频率无关。该研究在光载射频链路的长距离传输中有重要的应用价值。     

OFDM-ROF下行链路的性能研究

OFDM技术与ROF技术结合为实现低成本、高速数据传输的移动网络提供了可能,但光纤链路的非线性以及无线信道的多径衰落降低了系统性能。在建立ROF下行链路的传输函数模型基础上,分析ROF下行链路对OFDM信号性能的影响。传输模型包括激光器,光纤链路以及无线信道。分析在不同光调制指数、光纤长度及无线多径信道下接收信号的误差矢量、三阶非线性失真和互调失真。仿真结果显示：随着调制指数、光纤长度的增加,以及无线信道的多径衰落使得接收信号性能下降。此分析为OFDM-ROF下行链路的线性化以及无线信道均衡方案选择提供了理论基础。     

面向宽带接入与泛在感知应用的基于双波长的线性化光载无线链路

Radio-over-Fiber ( RoF ) technologies have been considered to be a promising solution to broadband access and ubiquitous sensing. We present a novel approach using dual-wavelength lights to suppress the nonlinear intermodulation distortion in intensity-modulated RoF link both theoretically and experimentally. The system we proposed mainly consists of two Laser Diodes (LDs ) at different wavelengths, a commercial available Mach-Zehnder Modulator (MZM) and a Photo Detector (PD). More than 25 dB suppression of the Third-order Intermodulation Distortion (IMD3) is achieved by adjusting the wavelength and optical power of the laser. Besides , the output of the MZM is then sent to the photodetector via a single fiber, which simplifies the system complexity for distribution of RF signals over long distances .     

RoF非线性链路对OFDM信号的影响

正交频分复用OFDM（Orthogonal Frequency Division Multiplexing）与光载无线电ROF（Radio OverFiber）技术结合为实现低成本、高速数据传输的无线网络提供了可能。但RoF链路的非线性降低了系统性能。丈中在分析Machzehnder调制器的静态模型基础上,提出用Volterra级数与冲击响应分析模型相结合模型化RoF非线性系统。在此模型基础上分析Mach-Zehnder调制器以及射频放大器非线性对OFDM信号的影响。仿真分析显示非线性会使OFDM信号频谱展宽,降低信号幅度,并且随着光调制指数的增加误差矢量,带外干扰增加。为OFDM-RoF系统的线性化处理以及系统光调制器调制指教的选择提供了理论依据。     

超宽带光载无线系统及其关键技术

基于微波光子技术的超宽带光载无线（RoF）系统是未来低成本、高性能超宽带无线接入网络的重要解决方案,前人已有许多研究成果。基于已有研究成果,文章设计了基于全光矢量调制技术的光载无线（RoF）系统,使信号的频谱效率进一步提高;基于毫米波相移键控调制的全双工光载无线系统,可以大大简化基站的结构和光纤的铺设;多业务混合传送的光载无线系统,可以同时承载有线和多个无线信号的业务。文章还展示了一种基于RoF的高清视频传输平台。     

Multi-service small-cell cloud wired/wireless access network based on tunable optical frequency comb

In this paper, we demonstrate a novel multi-service wired/wireless integrated access architecture of cloud radio access network (C-RAN) based on radio-over-fiber passive optical network (RoF-PON) system, which utilizes scalable multiple-frequency millimeter-wave (MF-MMW) generation based on tunable optical frequency comb (TOFC). In the baseband unit (BBU) pool, the generated optical comb lines are modulated into wired, RoF and WiFi/WiMAX signals, respectively. The multi-frequency RoF signals are generated by beating the optical comb line pairs in the small cell. The WiFi/WiMAX signals are demodulated after passing through the band pass filter (BPF) and band stop filter (BSF), respectively, whereas the wired signal can be received directly. The feasibility and scalability of the proposed multi-service wired/wireless integrated C-RAN are confirmed by the simulations.     

A Passive Broadband Impedance Equalizer for Improving the Input Return Loss of Electro-Absorption Modulators

Based on the context of an electro-absorption modulator integrated laser and the industry's standard 7-pin package having a RF connector, a complete module design that incorporates a simple yet effective broadband impedance equalizer to improve the input return loss of electro-absorption modulators (EAM) is proposed. The passive broadband impedance equalizer effectively reduces the input return loss of the EAM from between -9.84 and -5.26 dB to between -11.5 and -9.35 dB over a frequency range from 4.4 to 12.2 GHz without having to add a resistor in series with the EAM or reducing the EAM absorption-layer capacitance from the value that was optimized for optimal optical performance.     

一种基于正交调制的WDM-PON和RoF混合接入网

提出了一种基于正交调制的WDM-PON和RoF混合接入网方案.在该方案中,射频信号和单播数据被正交调制到光载波上.在接收端采用不同的解调方案,分别得到单播数据和射频信号.该方案实现了有线和无线宽带业务的融合.实验显示了该方案在低射频载波频率下能得到较好的误码率.     

A 60 GHz Radio-Over-Fiber Network Architecture for Seamless Communication With High Mobility

We demonstrate a 60 GHz broadband picocellular Radio-over-Fiber network architecture that enables seamless connectivity for highly mobile end-users. Its seamless communication capabilities arise by the supported handover scheme that relies on a novel Moving Extended Cell (MEC) concept. MEC exploits user-centric virtual groups of adjacent cells that transmit the same data content to the user and utilizes a switch mechanism for restructuring the virtual multi-cell area according to the user's mobility pattern, so that a virtual antenna group moves together with the mobile user. We present the theoretical formulation for MEC and show that it can provide zero packet loss and call dropping probability values in high-rate wireless services for a broad range of mobile speeds up to 40 m/sec, independently of the fiber link distances. We also demonstrate the physical layer network architecture and switch mechanism both for a RoF network with a single 60 GHz radio frequency (RF) over each wavelength, as well as for a RoF configuration supporting simultaneous multi-RF channel transmission over each optical wavelength. The performance of the multi-RF-over-lambda network implementation is evaluated via simulations showing successful 100 Mb/s radio signal transmission over fiber links longer than 30 km. To this end, MEC can enable seamless connectivity and bandwidth guarantees in 60 GHz picocellular RoF networks being also capable of serving multiple users over the same wavelength in a RF frequency-division-multiplexed (FDM) approach.     

Digitizing radio-over-fiber transceiver based on optical tunable encoder and optical codewords

Radio over fiber (RoF) is a very attractive and promising technology for wireless access networks, because of several advantages such as providing huge bandwidth, inherent immunity to electromagnetic interference and reduced power consumption. The analog RoF networks cannot be used for the transmission of radio signals over long lengths of fiber due to the distortions induced by dispersion and nonlinearity of the optical link. The digitized RoF communication presents an interesting alternative to circumvent the limitations of ARoF networks. In this paper, we propose an all-optical DRoF (Digital RoF) scheme based on the optical encoding technique and optical codewords instead of modulation techniques. The proposed scheme is composed of an all-optical sampler, an all-optical thresholder and an all-optical encoder. The proposed all-optical DRoF design is simulated by implementing its three main components using the simulation platform, Optisystem. We have also studied the capacity of the proposed encoding architecture in terms of the maximum number of chips that can be supported. Furthermore, ARoF, DRoF and the proposed all-optical DRoF systems are compared based on the minimum bit error rate, the maximum quality factor, and the complexity and implementation cost.     

Simultaneous Transmission of Millimeter-Wave and Baseband Signals Using Wavelength Interleaving and Polarization Multiplexing for an Integrated Reconfigurable Access Network

A novel scheme for the simultaneous transmission of 1.25-Gb/s baseband (BB) signals and 155-Mb/s 60-GHz radio-over-fiber (RoF) signals is experimentally demonstrated. The BB and RoF signals are wavelength-interleaved and polarization multiplexed. Tunable filtering along with polarization demultiplexing are used to drop an RoF signal with the wavelength-interleaved BB signal. This scheme is suited for future reconfigurable ring/bus access networks to provide an integrated platform for BB and millimeter-wave services.     

ATM-based transport architecture for multiservices wirelesspersonal communication networks

This paper presents an ATM-based transport architecture for next-generation multiservices personal communication networks (PCN). Such “multimedia capable” integrated services wireless networks are motivated by an anticipated demand for wireless extensions to future broadband networks. An ATM compatible wireless network concept capable of supporting a mix of broadband ISDN services including constant bit-rate (CBR), variable bit-rate (VBR), and packet data transport is explored from an architectural viewpoint. The proposed system uses a hierarchical ATM switching network for interconnection of PCN microcells, each of which is serviced by high-speed, shared-access radio links based on ATM-compatible cell, relay principles. Design issues related to the physical (modulation), media access control (MAC), and data-link layers of the ATM-based radio link are discussed, and preliminary technical approaches are identified in each case. An example multiservice dynamic reservation (MDR) TDMA media access protocol is then considered in further detail, and simulation results are presented for an example voice/data scenario with a proportion of time-critical (i.e., multimedia) packet data. Time-of-expiry (TOE) based queue service disciplines are also investigated as a mechanism for improving the quality-of-service (QoS) in this scenario     

Effects of clipping and filtering on the performance of OFDM

Orthogonal frequency division multiplexing (OFDM) is an attractive technique for wireless communication applications. However, an OFDM signal has a large peak-to-mean envelope power ratio, which can result in significant distortion when passed through a nonlinear device, such as a transmitter power amplifier. We investigate, through extensive computer simulations, the effects of clipping and filtering on the performance of OFDM, including the power spectral density, the crest factor, and the bit-error rate. Our results show that clipping and filtering is a promising technique for the transmission of OFDM signals using realistic linear amplifiers     

基于正态分布宽带信号的无源互调特征行为分析

在现代无线通信中,无源互调是影响通信信号传输质量的重要因素。双音互调测试能够有效衡量无源器件的非线性特性,却无法准确预测出器件在宽带信号激励下的非线性失真。因此本文提出了一种基于正态分布的宽带信号激励下的射频连接器无源互调特性分析方法。通过双音互调测试,建立射频连接器无源非线性传输数学模型,并将基于正态分布的等效宽带信号作为非线性传输模型的激励源进行模拟仿真。结果表明,宽带无源互调功率分布与宽带信号功率分布相同,n阶宽带无源互调带宽为原宽带信号带宽的n倍,宽带信号的无源互调产物相较于双音测试信号有所增强,且信号的信噪比下降,说明宽带信号在传输过程中受到的干扰更加严重。电路仿真和数值计算呈现出良好的一致性,证明了本分析方法的有效性。     

ROF在无线宽带移动通信中的应用

文章从光载无线通信(ROF)的基本原理出发,提出了ROF在未来无线宽带移动通信中的多种应用方式,包括ROF技术在多体制无线接入重载中的应用以及ROF在无线移动网络中实现基站与光网络节点设备的互联等.总结了ROF的技术优势,提出了有待解决的关键技术问题.     

A 60-GHz-Band Analog Optical System-on-Package Transmitter for Fiber-Radio Communications

We developed an analog optical system-on-package (SoP) transmitter for a 60-GHz-band radio-over-fiber (RoF) link. The SoP transmitter consisted of an electroabsorption modulator, radio frequency amplifiers, and a bandpass filter. The 60-GHz RoF wireless link was prepared to measure the performance of the SoP transmitter. The transmission characteristics of 64-quadrature amplitude modulation (64-QAM) data of the 60-GHz RoF wireless link, including the SoP transmitter, were investigated by measuring the error vector magnitude (EVM) and signal-to-noise ratio (SNR) with a baseband frequency. The EVM of the 60-GHz RoF wireless link was between 2.25% and 2.80%, and the SNR was between 27.36 and 29.31 dB from 140 and 770 MHz, at input baseband power of -9 dBm. The noise figure had the minimum of 8.44 dB at 500 MHz. We successfully transmitted digital community antenna television (CATV) system signals through the 60-GHz RoF wireless link, including the SoP transmitter. Digital CATV signals of 86 channels could be transmitted through the 60-GHz RoF wireless link, and the total throughput was found to be 2.61 Gb/s.