无源光网络标准发展及关键技术研究

无源光网络(Passive Optical Network,PON)作为当今接入网的主要技术解决方案,具有带宽使用效率高、传输距离远、抗干扰能力强等特点.通过研究PON技术的发展动态,本文首先归纳了各种PON技术的产生背景和应用特点,整理出各技术间的连接关系及主要标准;其次介绍了PON技术的帧结构,并对带宽、波长、传输模式等PON技术的主要参数进行了汇总;然后将国内外研究热点进行划分,围绕媒体访问控制协议、帧结构、动态带宽分配算法、节能机制等关键技术,阐述了其研究现状及在PON中的重要作用;最后对PON技术的发展趋势进行了展望.     

Some triplet energy-transfer reactions initiated by photoexcitation of triplet excited state of dibenz[a,h]anthracene to the higher triplet excited states

Some triplet energy-transfer reactions initiated by photoexcitation of the triplet excited state of dibenz[a,h]anthracene to higher triplet excited states (DBA(T_n)) were observed in the presence of the triplet energy quenchers (Q) such as naphthalene, biphenyl, p-dichlorobenzene, and o-dicyanobenzene. In the case of carbon tetrachloride (CCl₄) as Q, DBA(T_n)-sensitized decomposition of CCl₄ occurred.     

Formation of polyketone particle structure by hexafluoroisopropanol solvent evaporation and effects of plasticizer addition

Few solvents are capable of dissolving polyketones (PKs). 1,1,1,3,3,3‐Hexafluoro‐2‐propanol (hexafluoroisopropanol, HFIP) is a better solvent than trifluoroethanol and m‐cresol. When HFIP was evaporated from a PK/HFIP solution, a porous cast‐film with a microparticle structure was formed because the isotactic PKs adopted a helical conformation, and convection during evaporation of the high polarity and low‐boiling‐point HFIP caused aggregation and rolling of the polymer molecules. The addition of plasticizer suppressed particle formation, improving the surface structure and mechanical properties of the film. In particular, the dielectric properties of the film improved significantly. This will enable PKs, which are rigid insulating materials, to be used as dielectric materials, broadening their range of applications. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 887–892     

Facile and Rapid Synthesis of 4,5-Dihydrothiazol-2-ylamine Derivatives via Reaction Between Thiourea and Diaroylacetylenes

Heterocyclic systems 4,5-dihydrothiazol-2-ylamine derivatives are synthesized via an intramolecular thioiminoformamide annulation reaction.     

EPON系统中基于业务等级的动态带宽算法研究

本文针对EPON系统中上行链路的时分复用机制,提出了一种基于服务等级的动态带宽分配方案,通过自适应地改变权值及服务等级的阈值,以适应网络的状况,提高带宽利用率。通过这种方案,既保证了上行链路的高效利用,又保证了网络的性能,满足了网络业务的QoS要求。最后,通过实验证明了这种算法的正确性和可行性。     

基于GPON原理的城域传送体系研究

GPON技术具有带宽利用灵活,传输效率较高,管理功能完备的特点,已经开始在接入网中得到大规模应用。同时,目前城域网接入侧也亟需引入一种可对各种业务统一承载的传送技术,以缓解由于大量分组业务激增而对网络造成的扩容压力。基于以上要求,提出了一种基于GPON中DBA原理的城域业务传送体系,并搭建仿真平台,对采用该技术的基站回传网络在3G与LTE时代进行扩容的时间点进行分析,并与MSTP网络进行对比。结果表明,该技术与MSTP技术相比具有更高的传送效率,网络扩容的时间点相对MSTP网络得以推后,因而降低了移动回传网络的运营成本。     

Dynamic Subcarrier Assignment for OFDM-PON Network Based on RSOA for ACCORDANCE

In this paper, we overview the principle of Orthogonal Frequency Division Multiplexing Passive Optical Network （OFDM-PON） systems, with a particular focus on upstream architectures capable of achieving 10Gbit/s colorless upstream transmission using Reflective Semiconductor Optical Amplifier （RSOA）. We propose an architecture of RSOA based OFDM-PON which can achieve 10Gbit/s upstream transmission over a single wavelength. A novel Dynamic Subcarrier Assignment （DSA） algorithm is also proposed to support my architecture, namely Service based Polling in Pipeline （SPP） dynamic subcarrier algorithm. A simulation was conducted to study the performance of SPP algorithm. Compared with the traditional dynamic bandwidth allocation algorithms, service based polling meets the quality of in pipeline algorithm service requirements excellently, and adapts orthogonal frequency division multiplexing passive optical network better with higher bandwidth efficiency and lower algorithm complexity.     

Efficient medium arbitration of FSAN‐compliant GPONs

The steadily rising demand for multimedia and data services, the falling cost and omnipresence of Ethernet and the maturity of passive optical networks (PON) technology, promise to radically change the landscape in the local loop. The heart of a gigabit PON system (recently standardized by FSAN/ITU) is the medium access controller (MAC), which arbitrates access to the upstream link among users with fluctuating traffic demands and effects the multiplexing and concentration policy. At the same time, it has to safeguard the service quality and enforce the parameters agreed in the service level agreements (SLAs) between the users and the service provider. In this paper, a MAC protocol designed to serve any mix of services according to their quality of service (QoS) needs, employing four priority levels along with a high number of logically separate data queues is presented. The architecture and implementation in hardware of a MAC algorithm capable of allocating bandwidth down to a resolution of a byte with QoS differentiation is the focus of this paper. It employs the bandwidth arbitration tools of the FSAN/ITU G.984.3 standard and maps SLA parameters to GPON service parameters to create an efficient, fair and flexible residential access system. Copyright © 2005 John Wiley & Sons, Ltd.     

一种新的HomePNA网络动态带宽分配算法

基于同轴的家庭电话线网络联盟(HomePNA)3.0网络是一个上下行共享同一频段,使用同步媒体接入控制(SMAC)或异步媒体接入控制(AMAC)方式工作的系统.为保障视频、语音和数据等多业务的服务质量(QoS)特性,文章提出了一种新的动态带宽分配算法,即高优先级业务基于流的带宽预留和低优先级业务基于流量统计的上行带宽分配.给出了模型和仿真结果,证明了这种算法的正确性.     

一种WDM-PON系统中基于SLA的动态带宽算法

文章提出了一种基于业务等级协议(SLA)的动态带宽分配算法,该算法根据SLA为光网络单元(ONU)分配带宽权重和相应的优先权,确保了ONU的带宽分配和服务质量,改善了网络的性能,满足了网络业务的QoS要求.最后,通过仿真证明了这种算法的正确性.