Multichannel FM video transmission using travelling-wave laseramplifier in 1300 nm subcarrier multiplexed optical system

A 1300 nm travelling-wave laser amplifier has been employed to provide a power gain of 10 dB in a subcarrier multiplexed optical communication system which carried 10 broadcast quality C-band satellite FM video signals     

60-channel FM video subcarrier multiplexed optical communication system

A subcarrier multiplexed (SCM) optical communication system is described which transmits 60 frequency-modulated (FM) video channels over 18 km of single-mode fibre with a 56 dB weighted signal/noise ratio.     

波分复用系统中色散系数选择优化设计

对传输容量为4 × 2.5Gb/s、传输距离为300km的波分复用系统进行了仿真实验.在考虑了非线性效应的情况下,分析了不同色散系数对系统性能的影响.仿真结果表明,在路径平均色散为零的波分复用光纤线路中,色散系数选择在20～30ps/(nm·km)左右系统性能最优.     

A framework design for the next-generation radio access system

Extensive use of the Internet and huge demands for multimedia services via portable devices require the development of packet-based radio access systems with high transmission efficiency. Advanced radio transmission technologies have recently been proposed to achieve this challenging task. However, few researches have been reported on the design of an integrated system that can efficiently exploit the advantages of these transmission technologies. This paper considers the design of a packet-based cellular system for next-generation radio access. We propose a novel system framework that can incorporate various advanced transmission technologies such as link adaptation, opportunistic packet scheduling, channel coding, and multiantenna techniques. For efficient use of these technologies together, we first investigate the interoperability between these technologies by proposing a so-called cause and effect analysis. Based on this investigation, we design a differentiated-segments-based orthogonal frequency-division multiplexing system, called DiffSeg, to accommodate heterogeneous operating conditions in a seamless manner. Simulation results show that the proposed DiffSeg system can provide a nearly optimum performance with flexible configuration in a wide range of wireless channel conditions.     

新一代多模光纤

按照以太网协议建设的光纤局域网的传输速率正迅速升级到1Gbit/s和10Gbit/s这时光纤提出了更高的要求。IEEE正在制定10Gbit/s以太网标准,10Gbit/s以太网标准将考虑采用新一代的多模光纤。文章产 叙述新一代多模光纤的发展前景,然后综述了新一代多模光纤概念、测量新一代多模光纤带宽的新方法和制造新一代多模光纤的技术。     

Call blocking probability and bandwidth utilization of OFDM subcarrier allocation in next-generation wireless networks

Various studies have devised OFDM subcarrier-allocation schemes in next-generation wireless networks. However, the subcarrier-allocation system performance has seldom been assessed, especially in terms of the call blocking probability (CBP) and bandwidth utilization.(BU). This study proposes a batch-arrival bath-loss queueing model to evaluate the performance or the subcarrier-allocation system,and derives expressions for calculating two important system performance measurements, CBP and BU. Simulation results. indicate that the measures appear to work. The model should be helpful for constructing OFDM based wireless networks.     

A next-generation optical regional access network

We describe an optical regional access network which combines electronic IP routing with intelligent networking functionality of the optical WDM layer. The optical WDM layer provides such networking functions as network logical topology reconfiguration, optical flow switching to offload traffic and bypass IP routers, wavelength routing of signals, protection switching and restoration in the optical domain, and flexible network service provisioning by reconfigurable wavelength connectivity. We discuss key enabling technologies for the WDM layer and describe their limitations. The symbiosis of electronic and optical WDM networking functions also allows support for heterogeneous format traffic and will enable efficient gigabit-per-second user access in next-generation Internet networks     

基于Nyquist脉冲副载波调制的短距离光纤传输技术研究

提出了一种适用于强度调制直接检测(IM/DD) 光系统的信号调制格式。这种基于Nyquist脉冲half cycle副载波调制(SCM)信号能有效提高频谱效率,为了减少传递函数引起的系统的性能 恶化,采 用了数字预均衡和后均衡实现对光纤损伤的补偿;建立了偏振复用(PDM)IM/DD系统 平台, 分析了Nyquist脉冲SCM信号在系统中的PAPR性能,实现了72Gbit/s 64-QAM N yquist脉冲SCM信号经过20km标准单模光纤(SMF)传输后其误码性能 小于前向纠错(FEC)阀值3．8×10－3。     

Ultralong dispersion-shifted erbium-doped fiber amplifier and itsapplication to soliton transmission

Distributed, dispersion-shifted erbium-doped fiber amplifiers with doping concentrations as low as 0.1-0.5 p.p.m. (0.1-0.5×10^-4 wt.%) were fabricated and their grain characteristics studied for the purpose of soliton amplification. A 9.4-km dual-shape-core-type amplifier with a 0.5-p.p.m. concentration had a gain of more than 20 dB at 1.535 μm and 10 dB at 1.552 μm with a forward pumping configuration, and it could successfully amplify and transmit a 20-ps soliton pulse train at a 2.5-GHz repetition rate. The soliton transmission characteristics of an 18.2 km long fiber amplifier were studied using backward and forward pumping. It was found that A=1.5 soliton pulses with a pulse width of 20 ps could be amplified over 18.2 km at a repetition rate of 5 GHz, where soliton narrowing to 16 ps was observed     

AM光纤传输系统性能分析

1　ＶＳＢ -ＳＣＭ -ＡＭ光纤系统的噪声特性ＶＳＢ -ＳＣＭ -ＡＭ光纤传输中的主要噪声源如图 1所示。图 1　ＡＭ光纤传输中的主要噪声源分析整个系统的噪声特性 ,首先从ＰＤ的灵敏度和信噪比入手。当入射一个光子时 ,理想情况是它的能量ｈｆ能使一个电子跃迁入导带而成为载流子。但实际情况并非如此 ,产生电子数和入射的光子数的比例就是量子效率 ,用 η表示 ,则ＰＤ的输出电流可由下式给出 :Ｉ0 =ｅηｐｈｆ (1)(1)式还没有考虑到光被调制的情况 ,如果用调制度为ｍ的正弦波对光的功率进行调制时 ,信号电流的有效值由下式给定 :Ｉ=ｍｅｐ…     

Analysis of simultaneous digital and analogue signal transmission in a coherent optical subcarrier multiplexed system

The performance of the coherent subcarrier multiplexed system with mixed digital and analogue signals is analysed. The result shows that the performance of the digital channels in this system may be better than the pure digital system if the modulation index of the analogue channel is less than half of the modulation index of the digital channel. It is predicted that the system will have a 14 dB improvement over the corresponding intensity modulation/direct detection system.<>     

高速光纤系统中光双二进制传输性能分析

研究了光双二进制调制格式的传输性能,分析了光双二进制调制格式的不同实现形式及其对应的时频特性,并进行了仿真。在此基础上,讨论了采用低通滤波器实现光双二进制调制格式时滤波器带宽对调制码型的影响。     

An FM subcarrier data broadcast on bus transportation statusindication system

FM Subsidiary Communication Authorization (SCA) has been used to broadcast background music for a long time. Analog audio programs or digital data transmission services, utilizing SCAs, such as paging, stock market and headline news updates are common in people's daily life. Some demonstrations have been offered in the past to broadcast fax messages and some studies dealing with broadcasting video programs over the FM SCA channels. This paper focuses on using the FM SCA subchannel to transmit bus service status. This application provides the transmission of accurate status of public bus transportation services in order to offer better services. The status can be displayed on bus stations display boards or on personal computer receivers     

Generalized OSTBC‐based subcarrier intensity‐modulated MIMO optical wireless communication system

In this paper, we analyze an optical wireless communication (OWC) system having a source and a destination node, equipped with multiple transmit and receive apertures, respectively. We utilize generalized orthogonal space‐time block codes (OSTBCs) of any arbitrary order and subcarrier intensity modulation scheme for data transmission over gamma–gamma (GG) fading optical links using M ‐ary phase‐shift keying (PSK) constellation. A symbol‐wise decoding is utilized, and the closed‐form expression of the approximate average symbol error rate (SER) of multi‐aperture‐based OWC system is obtained for the generalized OSTBC and an arbitrary M ‐PSK constellation. Using the derived SER expression, we analytically evaluate the diversity order and the coding gain of the OWC system with GG atmospheric turbulence. It has been shown by the numerical results that the maximum possible diversity is achieved by using the symbol‐wise maximum likelihood decoding in the destination. Copyright © 2016 John Wiley & Sons, Ltd.     

Max-utility subcarrier allocation for heterogeneous services in wireless OFDM system

In future wireless network, one user will require multiple homogeneous or heterogeneous services simultaneously. Then, the scheduling algorithm is not only responsible for assigning a resource block to different users but also sharing the assigned resource block among multiple services for one user. Most of the traditional scheduling algorithms are designed to serve one service per user, and cannot be applied directly to this scenario because of the fairness criterion. This article focuses on adaptive resource allocation for multiple services per user at the downlink of orthogonal frequency division multiplexing (OFDM) based system. This article addresses this integrative resource scheduling problem based on utility function. First, the optimal algorithm for dynamic subcarrier allocation and share is deduced for homogeneous best-effort service system. Then the algorithm is extended to heterogeneous services system by classifying the delay sensitive service according to the head-of-line packet delay. The design goal is to maximize aggregate utility function to exploit multiuser diversity gain to the greatest extent even as guaranteeing quality of service (QoS) for delay sensitive service.     

Coherent optical fiber transmission

Essential technologies for developing coherent optical fiber transmission systems are reviewed from the viewpoint of regenerative repeater spacing and transmission data rate improvements. After describing the system features behind these advantages, recent progress in individual device and system technologies is delineated. Such progress includes frequency stabilization and linewidth reduction of semiconductor lasers, optical phase or frequency modulation, AM and FM noise suppression in coherent receivers, optical polarization stabilization and control in signal transmission, and optical direct amplification. Also described is progress in coherent optical transmission experiments carried out in many laboratories. Finally, future problems are discussed on the basis of the current state of the art.     

宽带CDMA无线接入系统及基站设计

宽带固定无线接入指的是从交换节点到固定用户终端部分或全部采用了无线方式.这里仅讨论对核心数据网络的接入.与有线接入比较,固定无线接入有如下显著特点:对自然条件适应性强.用户只要在覆盖区内,不需要特别定位和精确规划.在地形地物不适于架线铺缆的环境中,FWA系统显得尤其适合,建设速度快.     

残留边带调幅光缆电视光纤传输系统中的频道容量

与传统的电缆电视系统相比，残留边带调幅光缆电视光纤传输系统具有很大的优越性，因而对该系统的研究具有重要的产用意义。文中对ＭＡ－ＶＳＢＣＡＴＶ光纤传输系统的频道容量及其相关因素作了探讨，并导出了一些相关的计算公式。     

高速光纤传输系统的色散管理分析

对NRZ、RZ和CS-RZ码等三种码型在高速准线性传输系统中的性能进行了分析。通过对设计出相应色散管理方案的仿真,对其色散容限、抗非线性效应、抗噪声和抗偏振模色散性能进行对比分析。根据系统设计CS-RZ码的预色散补偿、后色散补偿和对称色散补偿等三种色散管理方案,并对三种方案的最大Q值进行残余色散优化,为现实系统的设计提供参考价值。