Showing papers in "Photonic Network Communications in 2015"
TL;DR: This paper proposes a novel structure for designing optical demultiplexer based on photonic crystal ring resonator, suitable for wavelength division multiplexing applications and uses four ring resonators for performing wavelength selection task.
Abstract: 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 $$-$$-19 dB.
68 citations
TL;DR: 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.
Abstract: 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.
64 citations
TL;DR: 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.
Abstract: 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.
54 citations
TL;DR: This work presents an exhaustive analysis and an accurate evaluation for spectrum fragmentation issue in flexible optical networks and proposes new metric for fragmentation measurements and some approaches to address such a problem.
Abstract: 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.
36 citations
TL;DR: This paper shows the first implementation of an active stateful PCE enabling elastic operations and hitless defragmentation of already provisioned LSPs and a tunable 400 Gbps superchannel of 4 PM-DQPSK sub-carriers controlled by a single tunable laser.
Abstract: 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 400Â Gbps superchannel of 4 PM-DQPSK sub-carriers controlled by a single tunable laser is proposed.
30 citations
TL;DR: This study proposes 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) to overcome atmospheric attenuation due to tropical rain and fulfill the growing demand for increased communication bandwidth and scalability.
Abstract: 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.
28 citations
TL;DR: Though the spectrum conversion capability can help improve spectrum efficiency for the $$p$$p-Cycle technique, the improvement seems not very significant for the static traffic scenario, and the spare capacity efficiency saturates.
Abstract: This paper considers the $$p$$p-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 $$p$$p-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 $$p$$p-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 $$p$$p-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.
25 citations
TL;DR: 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 are introduced.
Abstract: 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.
20 citations
TL;DR: A simple, generic measurement-based power consumption model is described and is shown to apply to equipment, networks and services.
Abstract: 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.
17 citations
TL;DR: This paper considers the challenging problem of joint relay selection and power allocation in FSO networks and proposes both centralized and distributed algorithms using bipartite matching and convex optimization to obtain highly competitive solutions.
Abstract: Drawing increasing attention, free-space optics (FSO) is a cost-effective technology to support data intensive communications. Cooperative diversity is considered to be an effective means for combating weather turbulence in FSO networks. In this paper, we consider the challenging problem of joint relay selection and power allocation in FSO networks. The objective was to maximize the FSO network-wide throughput under constraints of a given power budget and a limited number of FSO transceivers. The problem is formulated as a mixed integer nonlinear programming (MINLP) problem, which is NP-hard. We first adopt the reformulation-linearization technique (RLT) to derive an upper bound for the original MINLP problem. Due to the relaxation, the solutions obtained from RLT are infeasible. We then propose both centralized and distributed algorithms using bipartite matching and convex optimization to obtain highly competitive solutions. The proposed algorithms are shown to outperform the noncooperative scheme and an existing relay selection protocol with considerable gains through simulations.
14 citations
TL;DR: A path computation element (PCE)- based provisioning framework for carrier-grade multi-protocol label switching-transport profile (MPLS-TP) networks is presented and it is implemented and shown that the proposed framework not only simplifies the provisioning procedure with a single instance, but reduces the provisioned time in a MPLS-TP test bed.
Abstract: In this paper, we present a path computation element (PCE)- based provisioning framework for carrier-grade multi-protocol label switching-transport profile (MPLS-TP) networks. In the proposed framework, a centralized PCE integrates the service function as well as the path provisioning function into a unified provisioning controller. The service function allows the provisioning manager to initiate the establishment of a label-switched path (LSP). The provisioning function computes an optimal path, sets up and maintains the LSP in a unified way while directly configuring the LSP over the switches. The management function, as a separation from the provisioning function, can fully utilize the MPLS-TP switch to keep monitoring the performance of the provisioned LSP tunnels in a distributed way. The balanced partitioning of service provisioning and management functions reduces traffic load on the controller and improves the scalability. The software-defined provisioning control using an extended PCE communication protocol enables the cooperation between them to monitor and customize the LSPs flexibly and efficiently. We implement and show that the proposed framework not only simplifies the provisioning procedure with a single instance, but reduces the provisioning time in a MPLS-TP test bed.
TL;DR: Simulation results show that, compared to traditional method without bandwidth adaptability, BCP has better performance in terms of spectrum resource utilization and blocking probability.
Abstract: 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.
TL;DR: This work proposes an intra-domain software-defined network approach to select and turn off a subset of links to improve the energy efficiency of backbone networks by dynamically adjusting the number of active links according to network load.
Abstract: The continuous growth of traffic and the energy consumption of network equipments can limit the deployment of large-scale distributed infrastructure This work aims to improve the energy efficiency of backbone networks by dynamically adjusting the number of active links according to network load We propose an intra-domain software-defined network approach to select and turn off a subset of links The SPRING protocol (aka segment routing) is used to make our algorithms converge faster The algorithms--implemented and evaluated using the OMNET++ discrete event simulator--can achieve energy savings of around 44 % when considering real backbone networks
TL;DR: It is shown that the energy-efficiency performance is substantially independent of the recovery methods selected for risk mitigation, and it is demonstrated that backup resources can be switched off in the normal state without having a considerable impact from a financial viewpoint.
Abstract: 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 risk mitigation. It is also demonstrated that backup resources can be switched off in the normal state without having a considerable impact from a financial viewpoint.
TL;DR: A self-phase modulation-based duplex baseband radio over fiber architecture that gives good performance and cost-effective solution for duplex RoF communication over long distance is proposed.
Abstract: 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.
TL;DR: A simple analytical queuing model is introduced that considers the individual node loads to accurately characterize the throughput–delay performance of a clustered FiWi network and is employed to examine the impact of the number of clusters on the network throughput– delay performance.
Abstract: 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.
TL;DR: This paper studies a specific denial of service attack which is referred to as “BHP flooding attack”, which prevents legitimate traffics from reserving the required resources at intermediate core nodes and proposes the design of a reconfigurable BHP flooding countermeasure module that allows to counter against this type of attacks in an OBS network.
Abstract: 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.
TL;DR: This paper investigates the possibility to establish VLC links in shadowed areas, i.e., where the line of sight is blocked or unavailable, and shows that the system performance can be potentially improved when MIMO is considered for locations that have low performance with single photodetector.
Abstract: 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, ie, 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 $$\hbox {BER}=12\times 10^{-3}$$BER=12×10-3 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
TL;DR: This work proposes a fully distributed protection mechanism for a ring-based wavelength-division-multiplexed passive optical network (PON) broadband access architecture that can be utilized as an all-packet-based converged fixed-mobile access networking transport infrastructure for backhauling mobile traffic.
Abstract: This work proposes a fully distributed protection mechanism for a ring-based wavelength-division-multiplexed passive optical network (PON) broadband access architecture that can be utilized as an all-packet-based converged fixed-mobile access networking transport infrastructure for backhauling mobile traffic. Such an architecture will enable the true integration of PON-based and fourth-generation mobile broadband access technologies into the envisioned fixed-mobile platform. Specifically, this paper proposes two different fault detection and recovery schemes, namely, fully distributed and hybrid (distributed/centralized). In this ring-based architecture, each optical network unit can independently detect, manage, and recover most of the networking failure scenarios. The proposed protection schemes are capable of protecting against both node and distribution/trunk fiber failures and enable the recovery of all network traffic including upstream, downstream, and LAN data. In addition, these schemes can also protect against any combination of concurrent double failures including trunk/distribution fiber breaks and node failures. The hybrid architecture delivers these efficient resilience capabilities and incurs almost no additional power loss compared to that of the normal working architecture.
TL;DR: The RSA problem has been solved using a mixed integer linear programming formulation and the approaches compared with another recent formulation are compared.
Abstract: 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.
TL;DR: This work proposes 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.
Abstract: 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.
TL;DR: 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.
Abstract: 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.
TL;DR: Simulation results show that the proposed schemes can effectively accommodate the dynamic time-varying traffic while minimizing the network reconfiguration cost in SLICE networks.
Abstract: 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.
TL;DR: 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.
Abstract: 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.
TL;DR: This paper studies a horizon-based single-channel multi-class OBS node, for which the multiple traffic classes are differentiated using different offset time of each class, and obtains the Erlangian approximation for the finite time probability of the blocking time for a given class of burst in an OBS nodes.
Abstract: 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.
TL;DR: A bandwidth management scheme is introduced to ensure the QoS of each ONU and to maximize the total transmission efficiency at the same time and it is compared with exclusive bandwidth allocation scheme.
Abstract: 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.
TL;DR: This paper investigates and analyzes the performance of a set of key optical coding schemes that have been previously introduced for monitoring optical networks, and extends their application to metro ring networks and integrated metropolitan and access networks, referred as long-reach PONs.
Abstract: 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.
TL;DR: This paper revisits pervasive content caching and proposes an algorithm for cache replacement at ICN routers by incorporating principles from network coding, a technique used to achieve maximum flow rates in multicast.
Abstract: 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.
TL;DR: The results of the simulations indicate in general how OR of the transponders can influence the total network cost and power consumption in optical layer, while the automated networks with mixed-OR configuration can save power while the cost increases with respect to fixed-OR option.
Abstract: This paper deals with the methodologies to obtain the estimates of optical-layer power consumption and cost for long-haul optical networks using wavelength-division multiplexing (WDM) with IP-over-WDM and IP-over-MPLS-over-WDM network settings. Such optical networks generally employ wavelength routing at intermediate nodes and are known as wavelength-routed optical networks (WRONs). In WRON-based long-haul networks, optical reach (OR) of a transponder represents the maximum distance over which its optical signal can travel without any optical/electrical/optical regeneration and plays a significant role in deciding the power consumption and cost of the optical layer. In IP-over-WDM network setting, IP routers are directly interfaced with WRON and bandwidth requests are equal to the lightpath capacity. In IP-over-MPLS-over-WDM network setting, IP routers are interfaced with WRON via MPLS routers and bandwidth requests arrive as label-switched paths, which are generally lower than the lightpath capacity. We examine the above networks with mixed-OR nodes (transponders in each WRON node having different OR values but all transmitting at 10 Gbps) and fixed-OR nodes (transponders in each WRON node having same OR value and 10 Gbps transmission rate). In this investigation, two types of control planes are considered, namely unified control plane and isolated control plane. The network with unified control plane supports automated and dynamic resource provisioning for both short-term and long-term bandwidth requests. The study on nonautomated network using isolated control plane considers resource provisioning only for long-term bandwidth requests. Simulation-based network provisioning is carried out using C++, considering appropriate traffic models, OR constraints, node configurations and network architectures. The results of our simulations indicate in general how OR of the transponders can influence the total network cost and power consumption in optical layer. Overall, the nonautomated networks with mixed-OR configuration are found to save power and offer lower cost with respect to fixed-OR configuration, while the automated networks with mixed-OR configuration can save power while the cost increases with respect to fixed-OR option.
TL;DR: The proposed multipath extension for ESnet’s On-demand Secure Circuits and Advance Reservation System (OSCARS) provides an overlay onto the default OSCARS path computation engine that enables end users to route their data along multiple link-disjoint paths to provide session survivability and increase the degree of parallelism.
Abstract: Data generation is approaching petascale and exascale rates by cutting-edge science and research applications varying from material informatics to physics. With data generation and management comes the necessity to transmit such vast collections of information across the world's networks for processing, analysis, storage, or peer-sharing. This practice is becoming the norm to the large-scale scientific community, but complications can arise during networking. There are countless situations such as component failure due to a harmless construction accident or a devastating natural disaster that may lead to catastrophic interruption of service. Furthermore, given the size of datasets, there is a strong need to support intelligent and fast parallelism throughout the network to allow end users to efficiently consume available bandwidth. We therefore propose a multipath extension for ESnet's On-demand Secure Circuits and Advance Reservation System (OSCARS), the network research community's most popular long-lived circuit-provisioning software package. Presently, OSCARS supports purely point-to-point circuits; however, our proposed client software provides an overlay onto the default OSCARS path computation engine that enables end users to route their data along multiple link-disjoint paths to provide session survivability and increase the degree of parallelism. We have also adapted the proposed multipath extension to an existing anycast OSCARS deployment, which allows for the selection of one preferred destination node from among a set of potential candidates. Through thorough simulation analysis and exposure to realistic failure event distributions, we quantitatively evaluate the multipath client performance and showcase the relative benefits when compared to the standard single-path OSCARS deployment.