Physical impairments awareness based virtual network mapping strategy of elastic optical networks

As virtual networks services emerge increasingly with higher requirement of flexibility and robust, great complex challenges caused by physical-layer impairments are presented to the elastic optical networks(EON). Aimed to solve this problem, this paper proposes a physical impairment awareness based virtual network mapping stragegy of EON. The physical impairments awareness model is established, including both of linear factors and nonlinear ones. On this basis, this paper proposes a virtual network mapping strategy with detailed procedures, combined with node importance factors during the virtual network mapping procedure. Test results show that the proposed approach is able to reduce blocking rate and enhance services supporting ability of EON.     

Research on the multicast mechanism based on physical-layer-impairment awareness model for OpenFlow optical network

A physical-layer-impairment (PLI)-awareness based optical multicast mechanism is proposed for OpenFlow controlled optical networks. This proposed approach takes the PLI models including linear and non-linear factors into optical multicast controlled by OpenFlow protocol. Thus, the proposed scheme is able to cover nearly all PLI factors of each optical link and to conduct optical multicast with better communication quality. Simulation results show that the proposed scheme can obtain the better performance of OpenFlow controlled optical multicast services.     

采用线性自抗扰技术的高精度温度控制系统研制

随着光电检测技术的发展,红外气体检测技术在诸多领域有着广泛的应用。温度对于气体浓度及同位素丰度检测有着重要影响,采用比例-积分-微分(PID)控制算法的传统温度控制系统存在超调、响应时间慢和精度低的缺点。针对上述问题,首先使用COMSOL软件进行有限元分析,确定加热结构;然后以STM32单片机作为主控器件,通过16位AD芯片LTC1864进行实时温度数据采集;最后采用线性自抗扰算法(LADRC)算法调节PWM波,实现控制半导体制冷器(TEC)对系统温度的高精度实时动态调节。在19.8℃的环境温度下,进行目标温度为32℃的温控实验。结果表明,采用LADRC算法的温度控制系统在稳定工作时,温度波动标准差为0.035 7℃,相比于采用PID算法的温度控制系统,具有无超调、响应时间快和高精度的优点。     

TWC and AWG based optical switching structure for OVPN in WDM-PON

Considering the influence of more random atmospheric turbulence,worse pointing errors and highly dynamic link on the transmission performance of mobile multiple-input multiple-output(MIMO)free space optics(FSO)communication systems,this paper establishes a channel model for the mobile platform.Based on the combination of Alamouti space-time code and time hopping ultra-wide band(TH-UWB)communications,a novel repetition space-time coding(RSTC)method for mobile 2×2 free-space optical communications with pulse position modulation(PPM)is developed.In particular,two decoding methods of equal gain combining(EGC)maximum likelihood detection(MLD)and correlation matrix detection(CMD)are derived.When a quasi-static fading and weak turbulence channel model are considered,simulation results show that whether the channel state information(CSI)is known or not,the coding system demonstrates more significant performance of the symbol error rate(SER)than the uncoding.In other words,transmitting diversity can be achieved while conveying the information only through the time delays of the modulated signals transmitted from different antennas.CMD has almost the same effect of signal combining with maximal ratio combining(MRC).However,when the channel correlation increases,SER performance of the coding 2×2 system degrades significantly.     

Light-weighted services awareness scheme of the IP and optical converged network

As internet services newly emerge with diversity and complexity, great challenges and demands are presented to both IP network and optical network to support various services. Aimed to solve this problem, this paper proposes a light-weighted echo-state-network (LW-ESN) based services awareness scheme of the software defined IP and optical converged network. This LW-ESN model adopts the ring topology structure inside and generates the probability output result to determine the quality of service policy of IP and optical converged network. Moreover, the LW-ESN based service awareness engine is also designed in controller node of IP and optical converged network to perform services awareness by obtaining service traffic parameters from IP and optical layers, together with necessary working procedure. Simulation results show that the proposed approach is able to improve the services-oriented supporting ability in terms of blocking rate and delay time.     

Dynamic fragments awareness based virtual network mapping strategy of elastic optical networks

As virtual networks services emerge increasingly with higher diversification, the issue of spectrum fragments presents great challenge to the elastic optical networks (EON), especially under heaven services burdens. Aimed to solve this problem, this article proposes a dynamic fragments awareness based virtual network mapping (DFA-VNM) strategy of elastic optical network. In this proposed approach, the dynamic fragments awareness model of it is established, which takes available bandwidth demand and spectrum fragment degree into consideration. Moreover, the dynamic fragments awareness based virtual network mapping strategy makes full advantage of real-time fragments awareness result to conduct virtual network service mapping operation with less fragments and lower blocking rate. Testing results show that the proposed approach is able to improved services supporting ability of EON.     

Hierarchy Bayesian model based services awareness of high-speed optical access networks

As the speed of optical access networks soars with ever increasing multiple services, the service-supporting ability of optical access networks suffers greatly from the shortage of service awareness. Aiming to solve this problem, a hierarchy Bayesian model based services awareness mechanism is proposed for high-speed optical access networks. This approach builds a so-called hierarchy Bayesian model, according to the structure of typical optical access networks. Moreover, the proposed scheme is able to conduct simple services awareness operation in each optical network unit (ONU) and to perform complex services awareness from the whole view of system in optical line terminal (OLT). Simulation results show that the proposed scheme is able to achieve better quality of services (QoS), in terms of packet loss rate and time delay.     

基于AMI测量参数的电力线通信组网技术

针对电力线通信信号强度和时延指标无法准确测量,且网络建立过程中缺少路径权值和方向的问题,文章提出了基于AMI测量参数的路径指标间接测量方法。从AMI系统的智能电能表和集中器获取线路电压、电流、相位等测量参数,并以台区负荷中心的测量值为参考,利用基尔霍夫定律计算出不同相线测量点的电压损失大小和方向,也可结合线路材质参数计算出线路距离,从而实现了通信网络路径权值和方向的间接测量。为了验证方法的有效性,提出了一种采用AMI测量参数的p-persistent CSMA洪泛路由算法,实验证明该方法可有效缩短电力线通信网络路径深度和网络时延。     

分布式智能光网络中主动的区段预恢复机制(英文)

The development of Internet brings a great challenge to the survivability of the supporting distributed intelligent optical networks. The emergence of Active-Fault-Alarm (AFA) technology makes it possible for the system to be aware of the incoming or possible fault in advance and to provide possibility to develop a more active restoration mechanism. On this base, an Active Segment Pre-Restoration (ASPR) mechanism for distributed optical network is proposed. ASPR allows establishing a Segment Pre-Restoration...     

基于近红外吸收光谱技术的高精度CO2检测系统的研制

为了准确测量地震断裂带溢出的痕量CO₂气体浓度,文中采用可调谐半导体激光吸收光谱(TDLAS)技术,选取波数4 978.202 cm-1作为CO₂检测系统的吸收谱线,采用有效光程为40 m的多通池,以STM32作为主控和数据处理核心器件,研制了高精度CO₂检测系统。针对系统中的探测器噪声与光学干涉条纹噪声,利用卡尔曼-小波分析算法滤波提升系统性能。实验表明,与滤波前相比,系统在50 ppmv CO₂浓度下的二次谐波信噪比提升了2.06倍。在不同CO₂浓度下(50、300、1 000、4 000、8 000 ppmv),系统误差为2.57%～2.66%。系统测量4 000 ppmv浓度下的CO2时检测精密度达到20.9 ppmv。利用Allan方差分析得出,积分时间在约61 s时对应的最低探测下限(MDL)为5.2 ppmv,实现了对CO₂气体的高精度测量。结果表明,所设计的高精度CO₂系统可以在气体检测领域为预测地震前兆提供良好前景。