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  • 期刊名称:

    Photonic Network Communication

  • 中文名称: 光子网络通讯
  • 刊频: 0.765
  • ISSN: 1387-974X
  • 出版社: -
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  • 机译 无源光网络中基于小波包变换编码的上行数据传输方法
    摘要:A novel uplink data transmission method in electrical code division multiplexing passive optical networks is proposed, simulated and experimentally verified, in which each optical network unit (ONU) is assigned a special multilevel orthogonal code based on wavelet packet transform. Comparing with the normal bi-level orthogonal code by using Walsh code or Gold code, the proposed method can improve the bandwidth utilizations and reduce the optical beat noise. Simulation results show 31 ONUs, of which each data rate is 10Gb/s and total rate is 310Gb/s, can be transmitted 30 km. Three ONUs with each data at 622Mb/s over 50-km single-mode fiber is experimentally demonstrated.
  • 机译 主动PCE演示在灵活的网格光网络中执行弹性操作和无碎片整理
    摘要:Control and data plane innovations are driving the evolution of flexible grid optical networks enabling more granular reservation of spectrum portion. On the one hand, the path computation element (PCE) is evolving toward the stateful architecture to effectively perform reoptimization on existing LSPs. On the other hand, superchannels are emerging as an innovative technology to aggregate optical signals achieving high data rates and improved spectral efficiency. In this paper, we show the first implementation of an active stateful PCE enabling elastic operations and hitless defragmentation of already provisioned LSPs. An online reoptimization algorithm is employed to possibly move existing connections to allow elastic operations. The algorithm effectiveness is assessed in terms of overall network utilization through simulations. The experimental assessment includes both data and control plane evaluation. To demonstrate the hitless defragmentation, a tunable 400 Gbps superchannel of 4 PM-DQPSK sub-carriers controlled by a single tunable laser is proposed.
  • 机译 集群FiWi网络的简单分析吞吐量-延迟模型
    摘要:A fiber-wireless (FiWi) network integrates a passive optical network (PON) with wireless mesh networks (WMNs) to provide high-speed backhaul via the PON while offering the flexibility and mobility of a WMN. Generally, increasing the size of a WMN leads to higher wireless interference and longer packet delays. We examine the partitioning of a large WMN into several smaller WMN clusters, whereby each cluster is served by an optical network unit (ONU) of the PON. Existing WMN throughput-delay analysis techniques considering the mean load of the nodes at a given hop distance from a gateway (ONU) are unsuitable for the heterogeneous nodal traffic loads arising from clustering. We introduce a simple analytical queuing model that considers the individual node loads to accurately characterize the throughput-delay performance of a clustered FiWi network. We verify the accuracy of the model through extensive simulations. We employ the model to examine the impact of the number of clusters on the network throughput-delay performance. We find that with sufficient PON bandwidth, clustering substantially improves the FiWi network throughput-delay performance.
  • 机译 更新NCTUns-6.0工具以模拟全光超密集WDM系统的并行光突发切换
    摘要:Optical burst switching (OBS) is proposed as suitable switching architectures for directly transporting traffic over a bufferless wavelength division multiplexing (WDM) networks. Parallel optical burst switching (POBS) is a variant of the OBS model that takes this concept further by transmitting data bursts wavelength and time dimensions. However, there is a lack of simulator that simulates POBS networks. This paper presents an update to the conventional OBS model in the NCTUns-6.0 simulator (NCTU_(ns-POBS)). The NCTU_(ns-POBS) tool is capable of simulating POBS networks for ultra-dense WDM. It analyzes the features of POBS networks, enables to adjust the parameters of POBS networks and enhances their switching technology. To test and validate the performance of the tool, the proposed random wavelength assignment technique (RWAT) is compared with the existing sequential wavelength assignment technique (SWAT) of the POBS model and the conventional OBS model. The results of the simulation show that, the NCTU_(ns-POBS) successfully simulates the POBS networks in which the proposed RWAT enables the POBS to yield higher throughput compared to the existing SWAT and the OBS conventional technique.
  • 机译 光纤双工基带通信中基于自相位调制的多载波生成
    摘要:A self-phase modulation-based duplex baseband radio over fiber architecture is proposed, where data are transmitted up to six radio access units (RAUs) in distributed antenna system. Bidirectional full duplex 768 Mbps data transmission has been demonstrated, where data are transmitted from control unit to the base station (BS) and from BS to the RAUs over a distance of 20 km and 300 m, respectively. Our proposed architecture gives good performance and cost-effective solution for duplex RoF communication over long distance.
  • 机译 基于光子晶体环形谐振器的光波长解复用器
    摘要:Improving transmission efficiency, quality factor, channel spacing and crosstalk levels are the top priorities in designing optical demultiplexers, suitable for wavelength division multiplexing applications. In this paper, we proposed a novel structure for designing optical demultiplexer based on photonic crystal ring resonator. For performing wavelength selection task, we used four ring resonators. The resonance wavelength of the ring resonators depends on the dimensions of the ring core; therefore, we chose two different values for the lattice constant of the ring resonators core section. The channel spacing of the structure is about 3 nm, the minimum transmission efficiency is more than 95 %, the overall quality factor is more than 2,600, and finally the crosstalk levels are better than -19dB.
  • 机译 WDM网状网络的动态组播流量疏导中基于带宽比率的光树选择
    摘要:This paper studies the dynamic multicast traffic grooming problem in optical WDM mesh networks. A key step in dynamic multicast traffic grooming is to select a subset of exiting light-trees to support a new multicast request. A number of selection rules have been used in algorithms proposed in the literature. This paper proposes to use the bandwidth usage per multicast destination called bandwidth ratio as the light-tree selection criterion and to employ a light-tree selection rule that chooses the shortest-path tree branch with the smallest bandwidth ratio. Based on the light-tree selection rule, this paper develops an effective dynamic multicast traffic grooming algorithm. A number of performance measures including request blocking ratio, bandwidth utilization factor, unnecessary bandwidth utilization factor, mean number of light-trees per accepted connection request, and computation time are used to compare the proposed algorithm with other algorithms in the literature that employ various light-tree selection rules. Simulation results show that the proposed algorithm is able to make efficient utilization of the bandwidth resource and yield significantly lower request blocking ratio.
  • 机译 必和必拓洪水泛滥的脆弱性及对策
    摘要:Optical burst switching (OBS) is a switching technology that can efficiently operate in the optical core network using WDM technology and can also develop the future optical internet. The OBS switching technology presents a trade-off between the two switching technologies: optical circuit switching (OCS) and optical packet switching (OPS). This switching approach increases resource utilization compared with OCS technology and avoids the technological barriers of OPS networks. In OBS networks, many packets are assembled into one data burst at the edge node and a burst header packet (BHP) is sent before the burst transmission by an offset time in order to reserve the required resources in core nodes. This can cause security issues in the network and more specifically denial of service attacks that can occur if a source node is compromised. In this paper, we study a specific denial of service attack which we refer to as "BHP flooding attack", which prevents legitimate traffics from reserving the required resources at intermediate core nodes. We also propose the design of a reconfigurable BHP flooding countermeasure module that allows to counter against this type of attacks in an OBS network.
  • 机译 适用于数千兆位接入网的混合WDM /多光束自由空间光学器件
    摘要:Hybrid wavelength division multiplexing/ multibeam free-space optics (FSO) is a promising technique to overcome atmospheric attenuation due to tropical rain and to fulfill the growing demand for increased communication bandwidth and scalability. In this study, a hybrid four channel 1.25-Gb/s WDM/multibeam FSO network having four wavelengths with standard downlink channel spacing of 0.8 nm (100 GHz) is proposed. The hybrid WDM/multibeam FSO technique improved the performance of an FSO link in terms of the received power, link distance, data rate, and scalability. The proposed technique provided access data to four end users, each at a data rate of 1.25 Gb/s along an FSO link distance of 1,100 m.
  • 机译 调度需求的流量疏导,以最大程度地减少能耗
    摘要:The need for minimizing power consumption has long been an important consideration in wireless networks. In recent years, there has been a growing recognition of the need for developing energy efficient network design approaches for WDM backbone networks as well. The typical approach has been to switch off some components such as line cards and router ports during low demand periods and has focussed on traditional static and dynamic traffic models. In this paper, we propose a new approach that exploits knowledge of demand holding times to intelligently share resources among non-overlapping demands and reduce the overall power consumption of the network. We consider both the fixed window and sliding window scheduled traffic models, and present (ⅰ) a set of comprehensive integer linear program formulations and (ⅱ) a novel Genetic Algorithm (GA)-based strategy that jointly minimizes both power consumption and transceiver cost for the logical topology. The proposed approaches are used to determine the best route and time slot (for sliding window) for each demand and lead to significant improvements in terms of power consumption compared to existing techniques.
  • 机译 提高OPS / OBS缓冲区的调度算法的能效
    摘要:With ever-increasing demands for bandwidth, optical packet/burst switching is used to utilize more of the available capacity of optical networks. In existing prototypes of optical switches, packet contention is resolved by combining time and wavelength multiplexing by means of fiber delay lines and wavelength converters. Although optical switches dissipate less energy than their electronic counterparts, their consumption remains substantial. Since wavelength converters contribute significantly to the switches overall energy consumption, they should be powered only when needed. Existing scheduling algorithms, however, do not take the usage of wavelength converters (and the related energy consumption) into account. To this end, we developed and evaluated new cost-based scheduling algorithms, which take both gap and delay into account to schedule an incoming packet. The performance improvement of these algorithms over existing algorithms can be traded off for a significant reduction in up-time of the wavelength converters by introducing a conversion cost in the involved cost function. This is backed by Monte Carlo simulation results, in which the algorithms are applied both in a void-filling and non-void-filling setting. The algorithms are of the same implementation complexity as existing algorithms, and thus of immediate value to switch designers.
  • 机译 结合Gabriel图形模型进行FTTx尺寸标注
    摘要:For the realistic generation of synthetic street configurations, used in fiber-to-the-x (FTTx) dimensioning, the Gabriel graph model is proposed. Commencing the analysis with the Primal approach for 100 samples of urban street networks, a great heterogeneity is empirically discovered in their structural properties. Due to the observed morphological complexity, the necessity of a fast abstraction model capturing the complex street patterns is justified. The case study supports the sufficiency of Gabriel graphs for the reproduction of the street networks' basic structural properties such as the average shortest path, the diameter or the average street segment length. The results also demonstrate the sheer superiority of Gabriel graphs for the early estimation of the trenching length of FTTx networks with more than 48 % better accuracy in comparison with the conventional geometric models. Particularly in dense urban areas, the geometric models suffer more serious accuracy shortcomings, whereas the suggested model performs even better.
  • 机译 根据精选的ONDM 2014论文发行
    摘要:
  • 机译 灵活的光网络中的频谱碎片问题:分析和良好实践
    摘要:Flexible grid optical networks allow an efficient utilization of spectrum resources using 12.5-GHz frequency slot multiples instead of a fixed spacing, introducing however spectrum fragmentation (SF). In the literature, SF is often assumed to be a serious problem specifically in a dynamic traffic context. It is mostly related to the bandwidth blocking ratio due to the lack of relevant comparison criteria and efficient metrics. Besides, in operator core network, traffic behavior is instead incremental and it is forecasted for short periods of time in addition to some operational constraints that make of it a specific context. In this work, we present an exhaustive analysis and an accurate evaluation for SF issue in flexible optical networks. We also propose new metric for fragmentation measurements and some approaches to address such a problem.
  • 机译 光无线网络融合以支持节能型移动云服务
    摘要:Mobile computation offloading has been identified as a key-enabling technology to overcome the inherent processing power and storage constraints of mobile end devices. To satisfy the low-latency requirements of content-rich mobile applications, existing mobile cloud computing solutions allow mobile devices to access the required resources by accessing a nearby resource-rich cloudlet, suffering increased capital and operational expenditures. To address this issue, in this paper, we propose an infrastructure and architectural approach based on the orchestrated planning and operation of optical data center networks and wireless access networks. To this end, a novel formulation based on a multi-objective nonlinear programming model is presented that considers energy-efficient virtual infrastructure planning over the converged wireless, optical network interconnecting DCs with mobile devices, taking a holistic view of the infrastructure. Our modelling results identify trends and trade-offs relating to end-to-end service delay, mobility, resource requirements and energy consumption levels of the infrastructure across the various technology domains.
  • 机译 新型软件定义的Flex PON的演示
    摘要:Next generation optical access network needs more flexibility and programmable service provisioning to meet the future effective network operation and maintenance requirements. We propose a novel full-service software-defined Flex PON solution that has three innovative features: (a) DSP-enabled flexible transceiver and flexible link, (b) OLT side access network resource virtualization, and (c) software-defined programmable network functions and resource scheduling. We also experimentally demonstrate the three DSP-enabled flexible transceiver/link application scenarios. The first case uses single OFDM-based RF band that delivers 1.6/3.22/4.03/4.7 Gb/s to different ONUs with QPSK, 16QAM, 32QAM, or 64QAM modulations for achieving different optical power budgets of 36, 32, 30, or 28 dB, respectively. The second case uses dual RF bands to deliver wireless/video/data services in different bands dynamically, realizing a service-programmable capability based on the real network deployment requirements and link conditions. The third case demonstrates a multiband wireless signal transmission in a flexible frequency relocation manner to reuse the PON infrastructure.
  • 机译 光传输和网络社会中的挑战
    摘要:The fifth generation of mobile networks (5G) is the next major phase of mobile telecommunications that will enable the Networked Society. We describe the challenges and role of optical transport in the Networked Society. The paper covers the role of optical transport for 5G radio and SDN/NFV and the impact of integrated photonics with promise of low-cost DWDM which could serve as the basis for 5G transport satisfying requirements on performance, low cost and flexibility.
  • 机译 灵活的光网络中的动态连接建立和网络重新优化
    摘要:We consider the problem of dynamic connection establishment and spectrum defragmentation in flexible optical networks. When the spectrum is fragmented, blocking a connection establishment, the algorithm reactively re-optimizes the network by shifting ("pushing") in the spectrum domain and/or rerouting existing connections. We start by presenting an algorithm based on integer linear programming formulation that searches among all combinations of shiftings and reroutings and selects the one that minimizes the changes in existing connections. We also present a heuristic algorithm that recursively shifts/reroutes connections around a void. The solution space of the heuristic can also be very large, so we use a threshold on the recursion depth to reduce the complexity and also provide a trade-off between performance and running time. Our simulation results show that the blocking probability can be substantially reduced using the proposed techniques as opposed to a network that does not reactively defragments the spectrum. The proposed heuristic achieves near-optimal performance, for cases that we were able to find optimal solutions, while the selection of the recursion threshold was shown to provide a good trade-off of performance for running time.
  • 机译 路由,调制,频谱和发射功率分配,以最大化非线性光网状网络的业务吞吐量
    摘要:We investigate the optimization of routing, modulation format adaptation, spectral and launch power assignment as a means of improving the utilization of limited network resources and increasing the network throughput. We consider a transparent optical network operating in the nonlinear transmission regime and using the latest software adapted coherent optical techniques. We separate the problem into one of routing, modulation adaption and channel assignment, followed by channel spectral assignment, and launch power allocation. It is shown, for three test networks, that the launch power allocation and channel spectral assignment can improve the transmission SNR margin over the fixed modulation, fixed power, fully loaded link worst case by approximately 3-4 dB. This increase in SNR margin can be utilized through modulation format adaption to increase the overall network throughput. This paper highlights that increased gains in network throughput can be achieved in nonlinear impaired networks when individual transmitter spectral assignment and launch power are optimized to minimize the nonlinear interference.
  • 机译 p周期保护的弹性光网络的最佳设计
    摘要:This paper considers the -Cycle network protection technique in comparison with the ring cover technique for elastic optical networks. We develop Integer Linear Programming models to minimize required protection capacity and used link spectra in the whole network. We consider two spectrum conversion capabilities, i.e., no spectrum conversion and full spectrum conversion, for the -Cycle protection technique. We also apply the bandwidth squeezed restoration technique to obtain the maximum restoration levels for the affected service flows subject to limited frequency-slot capacity in each fiber link. Our studies show that the -Cycle technique shows much lower spare capacity redundancy than the ring cover technique. In addition, it is found that though the spectrum conversion capability can help improve spectrum efficiency for the -Cycle technique, the improvement seems not very significant for the static traffic scenario. It is also found that as the number of candidate cycles used in the design increases, the spare capacity efficiency saturates.
  • 机译 编排连接服务以支持数据中心联盟中的弹性操作
    摘要:Datacenter federations are able to manage appropriately the green energy resources available in each datacenter (DC) thanks to their geographically distributed infrastructure, thus reducing energy expenditure. Scheduling algorithms can compute virtual machine migration, transferring huge amounts of raw data from one DC to another to minimize operational costs and ensuring a certain Quality of Experience. Because green energy availability greatly depends on weather conditions, in this work we present a statistical model to improve green solar energy availability estimation accuracy and we use it in a mixed integer linear programming formulation to compute optimal virtual machine placement. Optical connections can be used to provide connectivity services of enough capacity to support those migrations. In particular, elastic optical networks can provide connections with multi-granular bitrate, which can be adapted on demand. DC resource managers can request optical connections and control their capacity. However, that scheme involves the resource managers to implement algorithms and interfaces to deal with network specifics and complexity. To solve that issue, in this paper we propose coordinating transfer-based inter-DC connectivity services; inter-DC connectivity is requested in terms of volume of data and completion time. We analyze cost savings when each connectivity model is applied in a DC federation. For the sake of a compelling analysis, exhaustive simulation experiments are carried out considering realistic scenarios. Results show that the notification-based model can save up to 20 % of energy costs and more than 40 % of communication costs in the evaluated scenarios.
  • 机译 流行网络故障下光传输网络恢复的策略
    摘要:The current trend in deploying automatic control plane solutions for increased flexibility in the optical transport layer leads to numerous advantages for both the operators and the customers, but also pose challenges related to the stability of the network and its ability to operate in a robust manner under different failure scenarios. This work evaluates two rerouting strategies and proposes four policies for failure handling in a connection-oriented optical transport network, under generalized multiprotocol label switching control plane. The performance of the strategies and the policies are evaluated under multiple correlated large-scale failures. We employ the Susceptible-Infected-Disabled epidemic failure spreading model and look into possible trade-offs between resiliency and resource efficiency. Via extensive simulations, we show that source rerouting outperforms on-site rerouting, and that there exist a clear trade-off between policy performance and network resource consumption, which must be addressed by network operators for improved robustness of their transport infrastructures. Applying proactive methods for avoiding areas where epidemic failures spread results in 50 % less connections requiring recovery, which translates in improved quality of service to customers and lower recovery expenses for the network operator.
  • 机译 增强型EPON中用于睡眠模式ONU的QoS感知节能机制
    摘要:Ethernet passive optical network (EPON) is a broadband access time-division multiplexing passive optical network technology which can be referred to as green network, as it has less power consumption compared with other networks. The optical network unit (ONU) is the best candidate to implement energy-saving adjustments in EPON. Turning off the ONU transmitter (Tx)/receiver (Rx) for substantial time is a common method to achieve the energy saving. However, setting overlong sleep duration decreases the QoS, while short sleep duration increases the ONU power consumption. The challenging issue is how to balance the trade-off between achieving energy saving and guaranteeing QoS. In this paper, we introduce an enhanced EPON architecture and a QoS-aware energy-saving mechanism to reduce ONU energy consumption and guarantee an overall QoS metric based on the ITU-T standards requirements. To achieve the energy saving in the upstream/downstream direction, two sleep durations are defined for the ONU's Tx/Rx to generate four ONU modes including active, transmission, doze, and sleep. Simulation results show that the proposed scheme improves the energy efficiency 44 % in average to fulfill the QoS metrics in terms of packet loss, delay and jitter, and the buffer requirement.
  • 机译 基于IEEE 802.11n光纤无线电的分布式天线系统中聚合机制的能效分析
    摘要:It is known that distributed antenna systems (DAS) using radio-over-fiber (RoF) links are able to increase coverage and to improve energy efficiency compared to traditional wireless access networks. In this paper, we focus on the energy efficiency of 802.11n RoF DAS architectures and we provide a methodology based on ns-3 to evaluate and optimize energy consumption in those environments. Our results confirm that there exists an optimal number of distributed antennas for a given scenario. Furthermore, we show that aggregation mechanisms included in IEEE 802.11n enable to further improve the energy efficiency in RoF DAS. Finally, we demonstrate that media access control protocol data unit aggregation techniques outperform media access control service data unit aggregation schemes in providing higher end-to-end throughput and a better energy efficiency in IEEE 802.11n RoF DAS.
  • 机译 能源效率与弹性:具有睡眠模式的光网络尺寸确定方面的风险意识视图
    摘要:This article proposes to solve the trade-off between energy-efficiency and resilience with a focus on business mechanisms. Risk engineering is used as a foundation. Financial impact (penalty) quantification with various compensation policies is applied, and business-relevant risk measures are used during the risk assessment. Then, risk mitigation strategies are evaluated to select the appropriate risk response. The approach is presented in networks with energy profiles supporting a sleep mode. An effective heuristic is used to assign flows, and it is shown that the energy-efficiency performance is substantially independent of the recovery methods selected for riskmitigation. It is also demonstrated that backup resources can be switched off in the normal state without having a considerable impact from a financial viewpoint.
  • 机译 面对能源可持续性架构的地铁交通网络中的交通爆炸
    摘要:The continuous growth of traffic volumes is making the consumed energy, in telecommunication networks, a critical issue. In this context, the implementation of new content distribution solutions will speed up this traffic increase. In particular, these solutions will significantly impact the traffic profile in metro networks. The current centralized traffic scenario will move toward a scenario in which the traffic exchanges would be distributed among all the nodes of the metro network. In this work, starting from a real traffic scenario, we estimate a possible traffic evolution, and we design the metro networks, according to different architectures, using integer linear programming formulations. The aim was to understand which architecture can better face the considered traffic evolution. The comparison is performed considering the energy consumption, the network setup and management, and the quality of service ensured by the architectures.
  • 机译 节能型千兆无源光网络的自适应状态转换控制
    摘要:In this paper, we investigate power management problems that affect gigabit-capable passive optical networks (GPONs). In GPONs, the basic principle for power reduction is to keep optical network units (ONUs) in the Power Saving state, wherein some of the hardware and software functions are turned off. Current research focuses on scheduling and determining the length of the sleep periods for ONUs that are in the Power Saving state. Our investigation indicates that keeping ONUs in the Power Saving state is not necessarily the most energy-efficient practice. The Power Saving state and the Full Power state must be jointly considered. Our study also reveals that traffic distribution is a critical factor. Considering only the average is insufficient. The variance of packet arrival also must be included when designing a green GPON. We have analyzed the power consumption in a GPON and determined the optimal load threshold for triggering a state transition from the Power Saving state to the Full Power state. For the reverse direction, we propose a neural network-based adaptive control scheme to achieve near optimal control of the transition from Full Power to Power Saving. We also propose a burst transmission scheme to determine the sleep period for an ONU in the Power Saving state. Unlike the proposal of ITU-T, which uses a fixed length for the sleep period, the state sojourn time in our approach is dynamically adjusted. We have carried out extensive simulations to evaluate the performance of the proposed scheme. Simulation results show that the total energy consumption of the proposed scheme is almost equal to the optimal control scheme.
  • 机译 关于TDMoPSN中抖动缓冲区的速率抖动性能:使用带有状态相关服务的排队模型进行研究
    摘要:Time-division multiplexing over packet-switched network (TDMoPSN) is an intermediate phase of transition from current synchronous TDM to future all-optical converged network. TDMoPSN is exclusively used to transport interactive voice traffic transparently over a PSN (e.g., IP, MPLS or Ethernet). The goal of this paper is to reduce rate-jitter that is introduced into a stream of packets carrying TDM payload. We have proposed two online algorithms, algorithm-A and algorithm-B, to reduce the rate-jitter and shown analytically that the rate-jitter achieved by algorithm-A is strictly less than the rate-jitter of online algorithm proposed by Mansour et al. [1]. We have used three stochastic processes, namely Poisson, Markov-modulated Poisson process (MMPP) and an arrival process with Pareto-distributed inter-arrival times (see [2-4]) for modeling the arrival of TDM packets (say, IP packets with single or many TDM frames as payloads) at the destination. We undertook statistical analysis of the proposed algorithms by modeling the jitter-buffer as and queues, to derive steady-state queue-length distribution, mean waiting time and distribution of inter-departure times. We also simulate the most realistic queueing model of our study and evaluated its performance with respect to the metrics: rate-jitter, mean waiting time, packet loss probability and steady-state queue-length distribution. Simulation results show that our proposed algorithms far outperforms the scheme proposed in [1]. We also present simulation results to verify the correctness of analytical queueing models. The algorithms proposed here are more general (for TDMoPSNs) and can be used to study TDMoIP, pseudowire, CES over metro Ethernet network (MEN), etc.
  • 机译 睡眠模式和流量需求如何影响光接入网的能源效率
    摘要:An ever-increasing bandwidth demand is the main driver to investigate next-generation optical access (NGOA) networks. These networks, however, do not only have to comply with increasing data rates, but they should also meet the societal green agenda. As the access part consumes a major fraction of the energy consumption in today's fiber-to-the-home-based telecommunication networks, the energy efficiency of NGOA networks should be an important design parameter. In this paper, we present a detailed evaluation of the energy consumption in different NGOA technologies. Furthermore, we analyze the effects of (1) introducing low power modes (e.g., sleep and doze modes) in the various NGOA technologies and (2) using optimal split ratios adjusted to the traffic demands so that the energy consumption is optimized for the desired quality of service level.
  • 机译 使用业务量预测的频谱切片弹性光路网络中的频谱分配
    摘要:Spectrum-sliced elastic optical path (SLICE) networks distribute data on a number of sub-carriers overlapped in frequency domain to provide efficient sub-wavelength and super-wavelength traffic accommodation. In SLICE networks, a routing and spectrum allocation algorithm assigns a spectrum path (SP) to any demand with just enough contiguous sub-carriers while following the spectrum continuity and the sub-carrier consecutiveness constraints. In this paper, we propose efficient sub-carrier allocation algorithms to assign sub-carriers to SPs whose spectrum demands could fluctuate with time. An integer linear programming model is developed to minimize the network reconfiguration and spectrum usage. Based on the historic traffic profile, an interference graph technique is proposed to facilitate the sub-carrier assignment. Simulation results show that the proposed schemes can effectively accommodate the dynamic time-varying traffic while minimizing the network reconfiguration cost in SLICE networks.
  • 机译 电信运营商网络能耗分析
    摘要:The operation of large-scale telecommunication networks requires energy in different forms. Besides fossil fuels, district heating, and fuels to operate a vehicle fleet, the major energy demand for telecom operator networks is that of electricity. Electricity is needed to power the telecom network itself, the data center equipment, and to supply power to the equipment in offices and workspaces-where the predominant electricity share is consumed by the classic telecom operator network. A large share of this telecom network electricity is currently consumed by legacy network parts inherited from the telephone network era, followed by mobile and fixed access networks with a multitude of distributed active elements for achieving countrywide coverage. Aggregation, core, and optical transport networks only consume modest shares of the overall telecommunication network electricity. The network equipment is accommodated in different classes of network production sites ranging from large indoor central offices to small outdoor sites. The higher their number is, the smaller the respective sites are. Smaller sites essentially provide coverage over large geographical areas and consume only small amounts of electricity per site; however, when combined, their share in total network electricity becomes major. Networking trends are driven by changing user and usage demands and the need to improve the network production efficiency: An example of the former in the wired network is the installation of smaller outdoor network sites to satisfy the increasing user demand for higher bit rate in a value-oriented access network rollout. A prominent example for the latter is the network platform consolidation in the transition toward all-IP networks. Results show that the multitude of small active access network sites for hybrid copper-fiber access systems require increasing amounts of energy for increasing access bit rates-which changes when using the latest copper access technologies or pure fiber-based passive optical access networks. Network platform consolidation improves the network energy efficiency by switching off legacy network platforms and enabling improved degrees of load-adaptive operation.
  • 机译 光网络能耗建模
    摘要:A simple, generic measurement-based power consumption model is described and is shown to apply to equipment, networks and services. This model is used to construct power consumption estimates for a diverse range of network scenarios including customer premises equipment and access, edge and core networks and services provided over a network.
  • 机译 数据中心网络中光互连的阻塞概率
    摘要:Cloud computing and Web-based applications are creating a need for powerful data centers. Data centers have a great need for high bandwidth, low latency, low blocking probability, and low bit-error rate to sustain the interaction between different applications. Current data center networks (DCNs) suffer from several problems such as high-energy consumption, high latency, fixed throughput of links, and limited reconfigurability. Electronic switches are low radix and have high latency due to a large hop count since each hop employs a store-and-forward mechanism. Optical interconnects, on the other hand, offer several advantages such as low-energy consumption, high bandwidth, reconfigurability, malleability to changing traffic, high-radix switch design, fast switching transition times, and wavelength multiplexing. These benefits provide the incentive to shift from electrical interconnects to optical interconnects in DCNs. Despite several advantages over their electrical counterparts, the performance of optical interconnects can be further improved by considering some performance parameters of optical interconnects. One such important parameter for the performance of any communication network is the blocking probability. This paper makes a comprehensive investigation of the performance of optical interconnects in different DCN architectures on the basis of blocking probability and concludes by suggesting ways to reduce the blocking.
  • 机译 TWDM-PON系统的容错和SLA支持架构
    摘要:In this paper, a protection architecture that can be applied to NG-PON2 system, or TWDM-PON, is proposed. NG-PON2 system provides bandwidth as much as 80 Gbps in downstream, and the system failure may cause a serious problem. Therefore, its protection becomes more important issue. We solved this problem by making a pair of OLTs protect with each other. If one OLT is out of order, the protection OLT provides service to two ONU groups in the proposed scheme. For this purpose, each OLT is equipped with two downstream wavelengths: one for itself and the other for the protection. It enhances the reliability of PON systems, which is essential for business application. Since the next generation PON system accommodates many types of users, its service level must be differentiated and this property should be maintained even during a protection mode. To meet this condition, we introduce a bandwidth management scheme to ensure the QoS of each ONU and to maximize the total transmission efficiency at the same time. A shared bandwidth allocation is used for this purpose, and it is compared with exclusive bandwidth allocation scheme. Performance of the proposed systems is studied through extensive analysis.
  • 机译 适用于接入和城域光网络物理层监控的特殊光编码技术的性能评估
    摘要:Many solutions have been proposed for fiber-fault monitoring in passive optical networks (PONs) during the last years. Optical coding has attracted particular attention for detecting fiber faults in PONs. These coding modules have particular characteristics that make it suitable for monitoring PON such as inexpensive, passive, and mature devices in their coding settings. In this paper, we investigate and analyze the performance of a set of key optical coding schemes that we have previously introduced for monitoring optical networks. We will derive their key design parameters and evaluate their performance in terms of signal-to-noise ratio, probability of misdetection, and probability of false alarm. We also show how this special category of coding techniques scales up to monitor also various complex architectures of networks. In effect, we extend this to wavelength division multiplexing (WDM) and TDM over WDM-PON. Moreover, we further extend their application to metro ring networks and integrated metropolitan and access networks, referred as long-reach PONs.
  • 机译 动态流量下混合线路速率光WDM网络的虚拟拓扑重新配置
    摘要:For the mixed-line-rate (MLR) wavelength-division multiplexing (WDM) networks, each wavelength in a fiber can provide different transmitting rates (in 10/40/100 Gbps) by using different modulation formats. Since the MLR-WDM becomes a cost-efficient technique for the network upgrading, the problem of supporting virtual topology reconfiguration (VTR) becomes an important issue. In this paper, the VTR problem is studied for MLR-WDM networks under dynamic traffic demand. By monitoring traffic of the lightpaths, a reconfiguration method is proposed to follow the changes in traffic without a priori knowledge of the future traffic pattern. The proposed algorithm can optimize resource utilization and network traffic performance by either adjusting (increasing or decreasing), adding or deleting one or more lightpaths at a time. Simulations reveal the effects of the various system parameters. Specifically, we find that the proposed method adapts very well to the changes in the offered traffic on MLR-WDM networks.
  • 机译 光学数据信号的安全过滤:基于码字的方法
    摘要:In this paper, we propose an all-optical filtering architecture that filters session establishment and data traffic streams. The session establishment filtering concerns the connection-oriented protocols. Each traffic stream is identified by a traffic identifier composed of a set of optical codewords. Each codeword is formed by a sequence of optical pulses that represent the bit "1" positions. In the case when an information bit "0" is transmitted, the transmitter does not generate a pulse. In a core node that implements the security filtering module, an optical security policy will be applied to the received traffic stream (session establishment or data traffic stream) based on its traffic identifier. The decision after performing the filtering process can lead to accept or reject the traffic stream. The proposed security filtering architecture is mainly composed of two modules: a session and a traffic filtering modules.
  • 机译 多类OBS节点阻塞时间的有限时间概率的Erlangian近似
    摘要:In an optical burst switching (OBS) network, the blocking time, representing the time interval during which the channel is occupied for a given class of incoming burst, is a key metric for performance evaluation and traffic shaping. In this paper, we study a horizon-based single-channel multi-class OBS node, for which the multiple traffic classes are differentiated using different offset time of each class. By assuming Poisson burst arrivals and phase-type distributed burst lengths and using the theory of Multi-layer stochastic fluid model, we obtain the Erlangian approximation for the finite time probability of the blocking time for a given class of burst in an OBS node. We further propose an explicit algorithm and procedure to calculate the Erlangian approximation. Numerical results are provided to illustrate the accuracy and the speed of convergence of the proposed method.
  • 机译 WDM网状网络上的绿色IP,具有连接可用性保证
    • 作者:Zhang, Xiaoning;
    • 刊名:Photonic network communications
    • 2015年第2期
    摘要:Energy efficiency has been well recognized as an important objective in IP over WDM mesh networks. In this paper, we study the problem of green IP over WDM mesh networks with connection availability guarantee under static traffic demands. We first present a virtual link power model for the two-layer networks, which is built on the power consumption value of the commercial network devices. Based on the energy-aware two-layer auxiliary graph, we propose a new heuristic algorithm named Availability-Guaranteed Energy-Efficient Design for Two-Layer Optical Networks (AGED_TON). The AGED_TON algorithm first constructs initial energy-efficient virtual topology on which connection requests are carried, and then routes working path and backup path of lightpaths on physical topology. In the procedure of AGED_TON algorithm, connection availability is considered for path calculating to achieve a good tradeoff between connection availability and energy efficiency. Compared with previous green networking algorithms, our proposed AGED_TON algorithm reduces energy consumption significantly and guarantees connection availability at the satisfactory level.
  • 机译 室内无视线可见光通信:调查和性能分析
    摘要:Visible light communication (VLC) using indoor LED lighting generally assumes the existence of line of sight link in addition to multipath, delayed, lower power reflections. In this paper, we investigate the possibility to establish VLC links in shadowed areas, i.e., where the line of sight is blocked or unavailable. First, we study the system performance in terms of received power, SNR, BER, and rms delay spread. The results show acceptable, yet promising performance of in worst non-line of sight case. Second, we define three configuration scenarios for receiver's PD orientation in which line of sight is absent. For each scenario, we evaluate the link performance. Our analysis shows that the system performance can be potentially improved when MIMO is considered for locations that have low performance with single photodetector.
  • 机译 一种用于光径网络中提高吞吐量的径道多分裂方法
    摘要:Light trail networks have been proposed as an extension of lightpath networks in order to enable sub-wavelength bandwidth allocation in WDM networks. The networks need a medium access control (MAC) method to avoid collisions of data transmissions. We have proposed a MAC method which adopts a token-passing mechanism. The method splits one trail into two trails: one upstream trail and one downstream trail and permits independent data transmissions on the trails. However, the method leaves bandwidths of links upstream from the token-holding node idle because the method only splits the original trail into two trails and leaves the upstream trail unsplit. In this paper, we propose a novel token-passing MAC method for further improving trail throughputs. Our proposed method recursively splits the upstream trail, and consequently the original trail can be split into more than two trails. In the proposed method, an appropriate setting of upstream/downstream token-holding times of all nodes is a key factor to successfully accommodate an input traffic. Therefore, we tackle a problem (called a token-holding time decision problem) where we optimize token-holding times of all nodes so that input traffic is successfully accommodated. We formulate the problem as a linear programming model. Numerical examples on maximum effective throughput show that the proposed method is more superior as the ratio of short-hop traffic is higher in input traffic patterns.
  • 机译 具有内容连接性的带宽适应性保护,可抵御弹性光学数据中心网络中的灾难
    摘要:Due to disasters in communication networks, the risk of large-scale failure is on the rise. Hence, how to recover failed requests caused by disaster with minimum spectrum resources is an important issue for network operators. In the past years, elastic optical networks provide a new way to reduce the spectrum consumption in optical networks. Based on the technology, bandwidth-adaptability protection with content connectivity (BCP) is proposed in this study. We first introduce the concept of BCP, which includes path calculation and spectrum allocation. For path calculation, working path and backup path employ links in different shared risk link groups to avoid disaster failure in optical networks. For spectrum allocation, modulation format of backup path is adjusted according to the requirement of point-to-content requests to reduce the spectrum consumption. Then, an integer linear program and two heuristic algorithms (BCP_KSP, BCP_MSP) are proposed for static and dynamic traffic scenarios, respectively. Simulation results show that, compared to traditional method without bandwidth adaptability, BCP has better performance in terms of spectrum resource utilization and blocking probability.
  • 机译 一种基于网络编码的光组播节点竞争解决方案
    摘要:Optical buffering using fiber delay lines (FDLs) has been proved to be the best choice to resolve contention for optical packet switching node. Due to the absence of optical RAM, XOR network coding becomes a new packet contention resolution technology in the all-optical networks. In this paper, we present an all-optical node architecture configured with a primary network coding module and a supplementary FDL buffer module for contention resolution. The contending packet is resolved by output shared XOR network coding module firstly without any time delay. The feedback shared FDL buffer is used to resolve the still packet contention after NC module, which is constructed by a FDL buffer loop group. Moreover, the minimum length-cascaded buffer scheduling technique (MLCBST) is designed to schedule the contending packet to available output with minimal transmission delay. The simulation results show that the proposed architecture and the MLCBST have an obvious effect on reducing the packet loss probability and decreasing the average delay for optical packet switching node.
  • 机译 基于知识的框架,用于设计光纤陆地网络上的毫米波(60 GHz)无线电
    摘要:This paper presents the research work involved in the development of a knowledge-based framework for the design of millimeter-wave 60 GHz radio over fiber (RoF) land networks. It combines object-oriented, rule-based, technical information, and procedural functions to support engineers in the conceptual and preliminary design of a network. The overall framework is organized in two main modules: the first module is a tutorial of the terminology and basic principles in the design of RoF networks. The second module is a design assistant system that requests input data from the user about the functional network requirements and its prioritized figures of merit. The proposed design assistant is capable of providing support on the major activities of the 60 GHz RoF land network design such as downlink and uplink channel assignment and network clustering, wavelength allocation, optical link design, and network integration. The assistant is user interactive through the implementation of a graphical user interface. To illustrate the validation of such framework, we present a case of study of a network design with specific requirements.
  • 机译 一种解决OFDM网络中路由和频谱分配问题的最佳启发式算法
    摘要:Orthogonal frequency division multiplexing (OFDM) has recently emerged as a promising technology. A network using OFDM- based spectrum-sliced elastic optical path (SLICE) has a higher spectrum efficiency, due to the fine granularity of subcarrier frequencies used. To minimize the utilized spectrum in SLICE networks, the routing and spectrum allocation problem (RSA) has to be efficiently solved. We have solved the RSA problem using a mixed integer linear programming formulation and have compared our approaches with another recent formulation.
  • 机译 关于5G传输网络的设计
    摘要:Future 5G systems will pave the way to a completely new societal paradigm where access to information will be available anywhere, anytime, and to anyone or anything. Most of the ongoing research and debate around 5G systems are focusing on the radio network segment (e.g., how to offer high peak-rates per subscriber, and how to handle a very large number of simultaneously connected devices without compromising on coverage, outage probability, and latency). On the other hand, understanding the impact that 5G systems will have on the transport network (i.e., the segment in charge of the backhaul of radio base stations and/or the fronthaul of remote radio units) is also very important. This paper provides an analysis of the key architectural challenges for the design of a flexible 5G transport infrastructure able to adapt in a cost-efficient way to the plethora of requirements coming from the large number of envisioned future 5G services.
  • 机译 用于混合WDM-TDM光接入网络的最小冗余共享OLT保护
    摘要:In this paper, a hybrid WDM-TDM-based optical access network architecture has been proposed that aims to provide optical line terminal (OLT) protection and partial feeder fiber protection without using any or minimal redundant OLT or any separate protection feeder fiber. The architecture is termed as minimal redundant shared OLT protection (MRSO) architecture. MRSO provides load shared OLT protection, where the ONUs of the failed OLT are supported by either another operational OLT that is lightly loaded in times of failure or by a redundant OLT located somewhere in the network. An appropriate control mechanism to enable communication among the mutually supporting OLTs has also been introduced. The control protocol enables distributed failure detection, updating of traffic load condition, and failure recovery. In MRSO, the remote node of the failed OLT can determine the node (OLT) that can take over the services along with the associated protection path depending on the current load condition. The paper further presents a new procedure for calculating availability of service for providing shared OLT protection. The availability of network service per end user subject to different failure scenarios within the proposed network architecture has been explored. Finally, our cost and scalability comparison shows that the proposed architecture provides significant cost and scalability benefit over previously proposed OLT protection schemes while achieving higher levels of network availability.
  • 机译 使用基于EDFA和基于RSOA的ONU的长距离WDM-TDM PON中的传输障碍
    摘要:In this paper, we present two possible architectures for wavelength division multiplexing-time division multiplexing hybrid long-reach passive optical network (PON) using reflective semiconductor optical amplifier (RSOA). We introduce both the upstream and downstream connectivity along with complete description of their working principles and implementation issues. Next we investigate the feasibility of the proposed architectures in the uplink direction in terms of bit error rate (BER) performance. The performance analysis has been carried out in the presence of realistic and non-ideal characteristics of optical and optoelectronic devices used for the setup. The BER is evaluated for both conventional and burst mode receivers, by considering all the noise components viz. ASE noise, thermal noise, shot noise and signal-ASE beat noise. To carry out the total network analysis, a novel steady-state model for RSOA is developed. Suitable steady-state models for erbium-doped fiber amplifier and arrayed waveguide grating have also been considered. The results demonstrate the limits of RSOA-based PON.
  • 机译 以信息为中心的网络中的集成网络编码和缓存:重新审视ICN框架中的普遍缓存
    摘要:Information-centric networks (ICNs) replace IP addresses with content names at the thin waist of the Internet hourglass, thereby enabling pervasive router-level caching at the network layer. In this paper, we revisit pervasive content caching and propose an algorithm for cache replacement at ICN routers by incorporating principles from network coding, a technique used to achieve maximum flow rates in multicast. By introducing a low computational cost in the system, network-coded caching better utilizes the available small storage space at the routers to cache more effectively in the network. Results of our experiments on the global enterprise for network innovations (GENI) testbed demonstrating the performance of our algorithm on a real network are included in the paper. We evaluate the algorithm in two different traffic scenarios (i) video-on-demand (VoD) (ii) Zipf-based web traffic. Working with the named data networking implementation of ICN, we also present the additional headers and logical components that are needed to enable network-coded caching. In a nutshell, we show that an integrated coding-and-caching strategy can provide significant gains in latency and content delivery rate for a small computational overhead.
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