Showing papers on "Optical Transport Network published in 2016"
TL;DR: The development of various OPM techniques for direct-detection systems and digital coherent systems are reviewed and future OPM challenges in flexible and elastic optical networks are discussed.
Abstract: Optical performance monitoring (OPM) is the estimation and acquisition of different physical parameters of transmitted signals and various components of an optical network. OPM functionalities are indispensable in ensuring robust network operation and plays a key role in enabling flexibility and improve overall network efficiency. We review the development of various OPM techniques for direct-detection systems and digital coherent systems and discuss future OPM challenges in flexible and elastic optical networks.
242 citations
TL;DR: The novel BBU-placement optimization problem for C-RAN deployment over a WDM aggregation network is introduced and formalized by integer linear programming, evaluating the impact of jointly supporting converged fixed and mobile traffic, and different fronthaul-transport options on the amount of BBU consolidation achievable on the aggregation network.
Abstract: 5G mobile access targets unprecedented performance, not only in terms of higher data rates per user and lower latency, but also in terms of network intelligence and capillarity. To achieve this, 5G networks will resort to solutions as small cell deployment, multipoint coordination (CoMP, ICIC) and centralized radio access network (C-RAN) with baseband units (BBUs) hotelling. As adopting such techniques requires a high-capacity low-latency access/aggregation network to support backhaul, radio coordination and fronthaul (i.e., digitized baseband signal) traffic, optical access/aggregation networks based on wavelength division multiplexing (WDM) are considered as an outstanding candidate for 5G-transport. By physically separating BBUs from the corresponding cell sites, BBU hotelling promises substantial savings in terms of cost and power consumption. However, this requires to insert additional high bit-rate traffic, i.e., the fronthaul, which also has very strict latency requirements. Therefore, a tradeoff between the number of BBU-hotels (BBU consolidation), the fronthaul latency and network-capacity utilization arises. We introduce the novel BBU-placement optimization problem for C-RAN deployment over a WDM aggregation network and formalize it by integer linear programming. Thus, we evaluate the impact of 1) jointly supporting converged fixed and mobile traffic, 2) different fronthaul-transport options (namely, OTN and Overlay ) and 3) joint optimization of BBU and electronic switches placement, on the amount of BBU consolidation achievable on the aggregation network.
134 citations
TL;DR: In this article, the capacity of the optical fiber channel has been investigated in the nonlinear regime and the intensity-dependent Kerr nonlinearity limit has been suggested as a fundamental limit to optical fiber capacity.
Abstract: Most of the digital data transmitted are carried by optical fibres, forming the great part of the national and international communication infrastructure. The information-carrying capacity of these networks has increased vastly over the past decades through the introduction of wavelength division multiplexing, advanced modulation formats, digital signal processing and improved optical fibre and amplifier technology. These developments sparked the communication revolution and the growth of the Internet, and have created an illusion of infinite capacity being available. But as the volume of data continues to increase, is there a limit to the capacity of an optical fibre communication channel? The optical fibre channel is nonlinear, and the intensity-dependent Kerr nonlinearity limit has been suggested as a fundamental limit to optical fibre capacity. Current research is focused on whether this is the case, and on linear and nonlinear techniques, both optical and electronic, to understand, unlock and maximize the capacity of optical communications in the nonlinear regime. This paper describes some of them and discusses future prospects for success in the quest for capacity.
96 citations
TL;DR: The physical media dependent layer recommendation (ITU-T G.989.2) is the result of over three years of collaborative work by members of the FSAN and ITU T Study Group 15, Question 2 groups.
Abstract: NG-PON2 is the industry's first multiple wavelength (per direction), standards-based passive optical network system that is compatible with power-split optical distribution networks. The physical media dependent layer recommendation (ITU-T G.989.2) is the result of over three years of collaborative work by members of the FSAN and ITU-T Study Group 15, Question 2 groups. This two-part paper provides the technical insight and rationales behind the recently approved standard. The first part of the paper focuses on optical link design topics, including the optical distribution network characteristics, wavelength plan, Raman fiber nonlinearity related degradation, and interchannel cross-talk tolerance. It also describes the wavelength-tuning capability of optical network units and its impact on the physical media dependent layer specification.
76 citations
TL;DR: In this paper, an optimal integer linear programming (ILP) formulation for the design of a flex-grid/SDM optical transport network that makes use of the transmission reach estimations is presented.
Abstract: Spatial division multiplexing (SDM) has been presented as a key solution to circumvent the nonlinear Shannon limit of standard single-core fibers. To implement SDM, multi-core fiber (MCF) technology becomes a top candidate that is leveraged by the very low inter-core crosstalk (XT) measurements obtained in real laboratory MCF prototypes with up to 22 cores. In this work, we concentrate on the design of MCF-enabled optical transport networks. To this goal, we present a methodology to estimate the worst-case transmission reach of the optical signals (at different bit rates and modulation formats) across MCFs given real laboratory XT measurements. Next, we present an optimal integer linear programming (ILP) formulation for the design of a flex-grid/SDM optical transport network that makes use of the transmission reach estimations. Additionally, an effective simulated annealing (SA)-based heuristic able to solve large problem instances with reasonable execution times is presented. Once the proposed heuristic is adequately tuned and validated, we use it to compare the resource utilization in MCF-enabled network scenarios against currently available multi-fiber link solutions. Numerical results reveal very close performances with up to 19 cores/fibers in national backbone network scenarios and up to 12 cores/fibers in long-haul continental ones.
68 citations
TL;DR: In this paper, a variety of optical self-coherent (SCOH) subsystems are reviewed, and reveal how they realize linear channels, while maintaining the simple and low-cost intensity modulation with direct detection (IM-DD).
Abstract: Intensity modulation with direct detection (IM-DD) dominates the commercial short-reach optical communications. However, when upgrading the data-rate distance product to 1000 Gb/s·km per wavelength and beyond, IM-DD faces severe performance barrier. Although a linear mapping exists between the intensity of transmitter and receiver in IM-DD back-to-back system, it becomes nonlinear under fiber channel impairments; for instance, the dominant chromatic dispersion. Coherent detection overcomes this fundamental obstacle by recovering a linear replica of the optical field instead of intensity. The local oscillator provides a reference carrier which mixes with the received signal, from which both intensity and phase of the signal can be recovered. Borrowing the idea from coherent detection, in DD system, a carrier can be sent along with the signal so that the receiver utilizes the reference carrier originated from transmitter; namely, the receiver conducts self-coherent (SCOH) detection. In this paper, we review a variety of optical SCOH subsystems, and reveal how they realize linear channels, while maintaining the simple and low-cost DD. SCOH can readily reach a data-rate distance product beyond 10000 Gb/s·km, making it suitable for the future high-speed short- and medium-reach applications, such as the data center interconnect, passive access network, and metropolitan area network.
57 citations
TL;DR: A framework for estimating the quality of transmission (QoT) of a new lightpath before it is established, as well as for calculating the expected degradation it will cause to existing lightpaths, is developed based on a graph transformation that exposes and models the interference between spectrum-neighboring channels.
Abstract: We develop a framework for estimating the quality of transmission (QoT) of a new lightpath before it is established, as well as for calculating the expected degradation it will cause to existing lightpaths. The framework correlates the QoT metrics of established lightpaths, which are readily available from coherent optical receivers that can be extended to serve as optical performance monitors. Past similar studies used only space (routing) information and thus neglected spectrum, while they focused on old-generation noncoherent networks. The proposed framework accounts for correlation in both the space and spectrum domains and can be applied to both fixed-grid wavelength division multiplexing (WDM) and elastic optical networks. It is based on a graph transformation that exposes and models the interference between spectrum-neighboring channels. Our results indicate that our QoT estimates are very close to the actual performance data, that is, to having perfect knowledge of the physical layer. The proposed estimation framework is shown to provide up to 4 × 10-2 lower pre-forward error correction bit error ratio (BER) compared to the worst-case interference scenario,which overestimates the BER. The higher accuracy can be harvested when lightpaths are provisioned with low margins; our results showed up to 47% reduction in required regenerators, a substantial savings in equipment cost.
50 citations
14 Nov 2016
TL;DR: It is found that optical links have a wide range of availabilities, which questions the common assumption in fault-tolerant routing designs that all links have equal failure probabilities, and that by monitoring changes in optical signal quality, one can better predict future outages.
Abstract: We analyze optical layer outages in a large backbone, using data for over a year from thousands of optical channels carrying live IP layer traffic. Our analysis uncovers several findings that can help improve network management and routing. For instance, we find that optical links have a wide range of availabilities, which questions the common assumption in fault-tolerant routing designs that all links have equal failure probabilities. We also find that by monitoring changes in optical signal quality (not visible at IP layer), we can better predict (probabilistically) future outages. Our results suggest that backbone traffic engineering strategies should consider current and past optical layer performance and route computation should be based on the outage-risk profile of the underlying optical links.
46 citations
TL;DR: The long-reach passive optical network (LR-PON) proposed in this paper extends the access network to hundreds of kilometers, and it can support more optical network units by wavelength division multiplexing technology.
Abstract: Network survivability and protection mechanisms are very important and necessary in optical networks. The long-reach passive optical network (LR-PON) proposed in this paper extends the access network to hundreds of kilometers, and it can support more optical network units by wavelength division multiplexing technology. We propose an efficient protection mechanism for the whole LR-PON. Optical encoders are used to monitor the whole network, and a network management system in the central office will initialize the protection process by monitoring the information it collects. When the network works normally, space division multiplexing technology is adopted to reduce the loss and crosstalk of signals. The designed system propagates the upstream and downstream signals in different fiber rings to mitigate the influence of Rayleigh backscattering. The proposed protection mechanism can protect the network from the multi-faults of fiber links with the designed switches. Furthermore, the loss, availability, costs, and network performance are also studied. The results obtained prove the feasibility of the proposed network. The network is costless and reliable, and it has high availability of up to 99.9992% by the protection mechanism.
41 citations
20 Mar 2016
TL;DR: A 260-meter security free-space optical data transmission link using orbital angular momentum beams multiplexing and 16-ary quadrature amplitude modulation signals is experimentally demonstrated.
Abstract: We experimentally demonstrate a 260-meter security free-space optical data transmission link using orbital angular momentum (OAM) beams multiplexing and 16-ary quadrature amplitude modulation (16-QAM) signals. We study the beam wandering, power fluctuation, channel crosstalk, bit-error rate (BER) performance, and link security.
40 citations
TL;DR: In this article, the authors considered optical node architectures for elastic optical networks and derived strict-sense nonblocking conditions for such $m$ -slot connections and compared them with each other.
Abstract: The paper considers optical node architectures for elastic optical networks. They use switching fabric topologies which are similar to the three-stage Clos switching networks. These architectures employ wavelength switching in the first and the third stages, and space switching in the second stage, and are also called W-S-W switching fabrics. In elastic optical networks, the optical spectrum is divided into frequency slot units. One frequency slot unit uses 12.5 GHz of bandwidth and an optical path may use $m$ adjacent frequency slot units. Such connection is called an $m$ -slot connection. For each architecture, strict-sense nonblocking conditions are derived and proved for such $m$ -slot connections. The number of center stage switches and the number of frequency slot units in interstage links are calculated and evaluated. The considered architectures are compared to each other. When the maximum number of frequency slot units that may be used by one connection, is not too high, these architectures can be implemented in practice.
TL;DR: A novel flat and scalable data center network (DCN) architecture based on fast (nanosecond) distributed buffer-less optical switches and efficient optical flow control and a preliminary experimental validation of the DCN is provided by using a 4 × 4 optical switch prototype.
Abstract: We propose a novel flat and scalable data center network (DCN) architecture based on fast (nanosecond) distributed buffer-less optical switches and efficient optical flow control. The proposed DCN architecture scales as the square of the port count of the optical switches. In order to investigate the performance of the proposed architecture, the system operation of an electronic Top-of-the-Rack (ToR) and the optical switch is fully described, and all functional subsystems are modeled. The performance in terms of DCN scalability, average latency, packet loss, normalized throughput of the network, and electronic buffer size of the ToR is numerically assessed for a medium-size data center supporting 5760 servers and a large-size data center connecting 100 000 servers. Considering a traffic pattern with high inter-cluster (40%) traffic distribution and buffer size of 40 KB, the results report an end-to-end latency of less than 8.1 $\mu\text{s}$ (including retransmission) and a packet loss $ under a load of 0.4 for the large-size data center. Moreover, we provide a preliminary experimental validation of the DCN by using a 4 $\times$ 4 optical switch prototype showing dynamic switching at 40 Gb/s and error-free operation with less than 1.5 dB penalty for the longest path.
TL;DR: In this paper, a bidirectional passive optical network (PON) architecture based on mode division multiplexing (MDM) has been proposed, which consists of fewmode fiber, passive mode multiplexer/demultiplexer, and few-mode circulators.
Abstract: Recently, mode division multiplexing (MDM) has been introduced into optical transmission systems and networks for capacity enhancement. In this letter, we propose a bidirectional passive optical network (PON) architecture based on MDM. The bidirectional optical distribution network of the MDM-PON consists of few-mode fiber, passive mode multiplexer/demultiplexer, and few-mode circulators, all of which are characterized by low modal-crosstalk. Signals in different modes are able to be transmitted and received independently for both downstream and upstream transmission. We experimentally demonstrate the bidirectional MDM-PON transmission over 10-km two-mode optical fiber. The 10-Gb/s ON–OFF-keying signals can be independently transmitted and directly detected without coherent receiver and multiple-input multiple-output processing. Moreover, nonlinear transmission impairments are experimentally investigated.
TL;DR: This paper proposes a provisioning strategy for a centralized radio access network with an optical transport whose wavelength resources can be dynamically shared among multiple RBSs, using a hierarchical software-defined networking control plane where a global orchestrator optimizes the usage of radio and transport resources.
Abstract: The next generation of mobile communication (i.e., 5G) will bring new challenges for the transport infrastructure, e.g., in terms of flexibility and capacity. The joint orchestration of radio and transport resources can help to address some of these challenges. One example is the possibility of reconfiguring the use of the transport network resources according to the spatial and temporal variations of the wireless traffic patterns. Using the concept of dynamic resource sharing, a limited pool of transport resources can be shared among a large number of radio base stations (RBSs), thus reducing considerably the overall deployment cost of the transport infrastructure. This paper proposes a provisioning strategy for a centralized radio access network with an optical transport whose wavelength resources can be dynamically shared among multiple RBSs. The proposed strategy utilizes a hierarchical software-defined networking control plane where a global orchestrator optimizes the usage of radio and transport resources. The benefits of the proposed strategy are assessed both by simulation and by experiment via an optical data plane emulator developed for this purpose. It is shown that the dynamic resource sharing can save up to 31.4% of transport resources compared to a conventional dimensioning approach, i.e., based on the overprovi-sioning of wavelength resources.
TL;DR: This paper investigates the power saving issue in the C-RAN, where it attempts to get a power consumption tradeoff between the optical transport network and the RRHs and develops an efficient local search algorithm, which includes three types of local improvement operations to address the intractable optimization task.
Abstract: Cloud radio access network (C-RAN) is deemed as a promising architecture to meet the exponentially increasing traffic demand in a mobile network. However, it needs a huge amount of transport capacity between the remote radio heads (RRHs) and the baseband unit pool. Though an optical transport network can be employed to support such a massive capacity, it always leads to enormous power consumption that is comparable with the transmission powers of the RRHs, which can significantly decrease the performance of the C-RAN if not well addressed. In this paper, we investigate the power saving issue in the C-RAN, where we attempt to get a power consumption tradeoff between the optical transport network and the RRHs. An RRH selection problem is formulated to achieve this goal, which is based on the traffic density of the service area. Our optimization task is to select a subset of the RRHs to minimize the total power consumption of the C-RAN while satisfying a series of network constraints, including the power and bandwidth budgets of the RRHs, the traffic demands of users, and the spectral efficiency. We develop an efficient local search algorithm, which includes three types of local improvement operations: “add,” “open,” and “close,” to address the intractable optimization task. Numerical results indicate that our proposal can significantly reduce the power consumption of the C-RAN. Moreover, our proposed algorithm converges stably and quickly, indicating that it is promising for applications.
TL;DR: In this article, the state of the art and future prospects and challenges of optical access networks are discussed, and a recent field demonstration of a novel tunable WDM-PON system with novel T-SFP+ modules is presented.
Abstract: We report on the state of the art and future prospects and challenges of optical access networks. Details on a recent field demonstration of a novel tunable WDM-PON system with novel T-SFP+ modules will be presented. Furthermore, the concept of centralized wavelength control of the optical network unit wavelengths will be explained as well as different realization options of pilot-tone based communication channels. Finally, a control concept for tuning the DS-DBR laser will be shown.
TL;DR: The error-free performance (BER <; 10-9) for all the connections confirms that the proposed architecture can meet the existing data center requirements.
Abstract: This paper reports on a novel ring-based data center architecture composed of multidimensional switching nodes. The nodes are interconnected with multicore fibers and can provide switching in three different physical, hierarchically overlaid dimensions (space, wavelength, and time). The proposed architecture allows for scaling in different dimensions while at the same time providing support for connections with different granularity. The ring topology reduces the number of different physical links required, leading to simplified cabling and easier link management, while optical bypass holds the prospect of low latency and low-power consumption. The performance of the multidimensional switching nodes has been investigated in an experimental demonstration comprising three network nodes connected with multicore fibers. Both high capacity wavelength connections and time-shared subwavelength connections have been established for connecting different nodes by switching in different physical dimensions. Error-free performance ( $\text{BER} ) has been achieved for all the connections with various granularity in all the investigated switching scenarios. The scalability of the system has been studied by increasing the transmission capacity to 1 Tbit/s/core equivalent to 7 Tbit/s total throughput in a single seven-core multicore fiber. The error-free performance ( $\text{BER} ) for all the connections confirms that the proposed architecture can meet the existing demands in data centers and accommodate the future traffic growth.
TL;DR: In this article, the authors investigate how to obtain the best compromise between harnessing the main benefits of next-generation optical interfaces, while keeping the complexity of the underlying system at a reasonable level.
Abstract: Next-generation elastic optical interfaces will support a wide range of line rates and modulation formats. Such transmission schemes enable doubling of the channel capacity at the expense of a lower reach, whereas a flexible DWDM grid supports the transport of multiple optical signals within a single frequency slot by packing them closely, thus saving spectral resources. The resulting multitude of options on the line side provides network planners the capability to derive the most suitable one for each individual path inside the network. However, planning and operational complexity should not be overlooked, since aspects such as added spectrum fragmentation can hamper the expected network improvements. This paper investigates how to obtain the best compromise between harnessing the main benefits of next-generation optical interfaces, while keeping the complexity of the underlying system at a reasonable level. In particular, we define a novel network spectral efficiency (SE) metric that enables, on one hand, to highlight the relevance of supporting a flexible grid to improve SE and, on the other hand, to demonstrate that the grid granularity can be based on coarser 50 GHz increments without major penalties. The effectiveness of this parameter has been verified by considering two reference network topologies. Finally, the paper also discusses how future optical interface technology developments will shape network design.
TL;DR: A feasible V-BVT architecture that can be a part of a software-defined optical network and achieves independence in virtual transceivers control and management in the control plane, while maintaining the coexisting and isolation features in the physical layer is presented.
Abstract: In order to serve the future high-performance network-based Internet applications, optical network virtualization is proposed to offer each application type a dedicated virtual optical network (VON). Virtualizeable bandwidth variable transceiver (V-BVT) is a key enabler in supporting the creation of multiple VONs. In this paper, we present a feasible V-BVT architecture that can be a part of a software-defined optical network. The proposed V-BVT has a novelty to offer independent operation, control, and management abilities to the clients or higher level network controllers. In addition, a specific V-BVT virtualization algorithm is proposed, in order to enable the efficient creation of multiple coexisting, but independent virtual transceivers that share the same V-BVT physical resources. The virtual transceiver can provide specific bit rate, subcarrier, modulation format, and a corresponding baud rate to each VON, based on the requirement of the VON demand, V-BVT resources availability, and optical network status. We further realize the proposed V-VBT architecture on an experimental platform with a software-defined network controller. The V-BVT resource allocation through the proposed virtualization algorithm is also performed using the extended OpenFlow protocol. The proposed and experimentally demonstrated V-BVT achieves independence in virtual transceivers control and management in the control plane, while maintaining the coexisting and isolation features in the physical layer.
TL;DR: A software defined networking scheme for quality of service provisioning through energy efficient assignment of optical transponders, employing bandwidth variable distance adaptive modulation and coding that enables avoiding over-provisioning of transponder capacity as well as short-term major changes in equipment allocation for networks with dynamic traffic.
Abstract: The over-provisioning of capacities in optical networks is not a sustainable approach in the long run. In this paper, we propose a software defined networking scheme for quality of service provisioning through energy efficient assignment of optical transponders, employing bandwidth variable distance adaptive modulation and coding. Our scheme enables avoiding over-provisioning of transponder capacity as well as short-term major changes in equipment allocation for networks with dynamic traffic. We make use of the seasonal auto-regressive integrated moving average model to forecast the statistics of network traffic for an arbitrary time span based on the requirements and the constraints of the service provider. The quality of service measure is defined as the probability of congestion at the core router ports. A stochastic linear programming approach is used to provide a solution for energy efficient assignment of optical transponders and electronic switching capacity while ensuring a certain level of quality of service to core routers. The scheduling of optical lightpath capacities is performed for the entire duration of time under consideration, whereas the scheduling of electronic switching capacities is performed based on the short-term dynamics of the traffic. Numerical results show up to 48% improvement in the energy efficiency of optical networks and 45% reduction in the number of optical lightpaths through the implementation of the proposed technique, compared to a design based on employing conventional fixed optical transponders and no traffic rerouting, where both schemes satisfy the congestion probability requirements.
TL;DR: In this article, a cognitive methodology for optical amplifier gain adjustment, that relies on case-based reasoning, showed optical signal-to-noise ratio improvements over time demonstrating the cognition process regardless the deployed amplifier type.
Abstract: Our recently proposed cognitive methodology for optical amplifier gain adjustment, that relies on case-based reasoning, showed optical signal-to-noise ratio improvements over time demonstrating the cognition process regardless the deployed amplifier type. In this paper, we extend our preliminary analysis exploring the cognitive methodology benefits for different and larger network topologies. The obtained results show agreement between networks, demonstrating the methodology suitability regardless the network scenario.
TL;DR: The proposed OGDCN framework supports any-to-any route reachability without using fast optical switching elements in the network, and is shown to be better than other architectures in terms of power consumption.
Abstract: With data center network traffic growing significantly, power-efficient optical and hybrid optical architectures are considered as an alternate to packet switching. Typically, hybrid optical architectures use fast optical switching elements to ensure any-to-any route reachability. In this paper, an optically groomed data center network (OGDCN) framework is proposed. The proposed framework supports any-to-any route reachability without using fast optical switching elements in the network. Different components can be combined to realize an OGDCN, as described in this paper. The framework is evaluated and compared to other architectures in terms of scalability and power consumption. A particular OGDCN realization is presented and is shown to be better than other architectures in terms of power consumption. The power consumption is lower by at least 47% than the next best existing architecture proposed in the literature.
20 Mar 2016
TL;DR: A model-based approach for building a transport SDN platform that uses operator-defined data models to build common APIs for managing multi-vendor optical networks consisting of terminal devices and line systems is described.
Abstract: We describe a model-based approach for building a transport SDN platform that uses operator-defined data models to build common APIs for managing multi-vendor optical networks consisting of terminal devices and line systems.
TL;DR: This work proposes an Nl1 protection mechanism to reduce backup OLTs in a resilient dual-homed LR-PON deployment and shows that the percentage of backupOLTs can be reduced by 6 times for Ireland and by 4 times for the UK compared to a 1 + 1 protection deployment scenario.
Abstract: Long-reach passive optical networks (LR-PONs) prove to be a suitable candidate for future broadband access networks. The longer reach of the feeder fiber in a LR-PON enables us to consolidate a large number of end users. The longer reach also eliminates a degree of electronic processing by eliminating the metro network and connecting the local exchanges (or the central offices) directly to a consolidated metro/core (MC) node. However, longer reach makes the feeder fiber more vulnerable to failures, and therefore, for resiliency purposes, a dual-homed architecture is proposed. For the usual case of 1 + 1 protection, the dual-homed secondary MC node would contain duplicate resources that would take over in the event of the failure of any of the individual working optical line terminals (OLTs) or the entire primary MC node in the case of a catastrophe. In this work we propose an Nl1 protection mechanism to reduce backup OLTs in a resilient dual-homed LR-PON deployment. We model the problem as an integer linear program and solve it for Irish and UK network deployments. Our results show that the percentage of backup OLTs can be reduced by 6 times for Ireland and by 4 times for the UK compared to a 1 + 1 protection deployment scenario.
TL;DR: A suboptimal iterative flipping method for solving the above NP-complete optimization problem is proposed, which achieves better performance than a simulated annealing scheme while consuming considerably fewer search iterations.
Abstract: This paper introduces a novel routing and bandwidth allocation strategy for orthogonal frequency-division multiplexing (OFDM)-based elastic optical networks, aiming to optimize the network operational expenditures in terms of energy consumption. Based on the previously reported analytical bit error rate model for an OFDM-based optical transmission line, an optimization problem is formulated to allocate a set of lightpaths according to realistic network topologies, where the routing path, modulation level, bandwidth, and optical transceiver power of each lightpath are jointly determined for achieving minimum power consumption. To reduce computational complexity, a suboptimal iterative flipping method for solving the above NP-complete optimization problem is proposed, which achieves better performance than a simulated annealing scheme while consuming considerably fewer search iterations.
20 Mar 2016
TL;DR: It is shown how margins can be reduced through proper design to increase network capacity and flexible optoelectronic nodes coupled with optical monitoring are key to fully leverage network margins.
Abstract: We review margins used in optical networks and show how they can be reduced through proper design to increase network capacity; flexible optoelectronic nodes coupled with optical monitoring are key to fully leverage network margins.
TL;DR: It offers optimistic thinking to show optical TDM at this phase as one of the future direction, where complex digital signal processing (DSP) and coherent optical communication are frequently demonstrated to serve the access network.
22 May 2016
TL;DR: This paper proposes three different Passive Optical Data Center Architectures (PODCAs), depending on the size of the network, and compares the power consumption and capital expenditure (CapEx) cost of PODCA with other recent optical data center network architectures such as DOS, Proteus, and Petabit.
Abstract: Optical interconnects for data centers can offer reduced power consumption, low latency, and high scalability, compared to electrical interconnects. However, active optical components such as tunable wavelength converters and Micro-Electro-Mechanical Systems (MEMS) switches suffer from high cost or slow reconfiguration times. In this paper, we propose three different Passive Optical Data Center Architectures (PODCAs), depending on the size of the network. Our key device is the Arrayed Waveguide Grating Router (AWGR), a passive device that can achieve contention resolution in the wavelength domain [1]. In our architectures, optical signals are transmitted from fast tunable transmitters and pass through couplers, AWGR, demultiplexers, and are received by wide-band receivers. Our architecture can easily accommodate over 2 million servers. Simulation results show that packet latency is below 9μs, and 100% throughput is achievable. We compare the power consumption and capital expenditure (CapEx) cost of PODCA with other recent optical data center network architectures such as DOS, Proteus, and Petabit. Results show that our architectures can save up to 90% on power consumption and 88% on CapEx.
IBM1
TL;DR: Up to 2x execution-time improvement is demonstrated for global traffic patterns in a >13,000-node system using a production-grade network simulator.
Abstract: We propose Optical Circuit Switching for dynamically creating reconfigurable partitions in large-scale systems with Dragonfly networks. Up to 2x execution-time improvement is demonstrated for global traffic patterns in a >13,000-node system using a production-grade network simulator.
TL;DR: The new characteristics (i.e., multiple operators, diversified services) aiming at the survivability problem in virtualized optical transport networks, and three novel protection schemes for VTNS against the new features are analyzed.
Abstract: Based on the virtualization technique in optical networks, virtual transport network services (VTNS) has been introduced as a new kind of service in transport networks. With VTNS, transport providers are able to provide their customers entire virtual topologies instead of traditional end-to-end connections. This letter analyzes the new characteristics (i.e., multiple operators, diversified services) aiming at the survivability problem in virtualized optical transport networks, and proposes three novel protection schemes for VTNS against the new features. For the first time, VTNS with the proposed protection schemes are demonstrated on the flexi-grid optical networks testbed with commercial optical transport equipments. Additionally, the performances of the proposed protection schemes have been evaluated via simulations.