Showing papers in "Photonic Network Communications in 2014"

TDOA-based indoor positioning using visible light

Abstract: In this paper, we propose an indoor positioning system in which the visible light radiated from LEDs is used to locate the position of receiver. Compared to current indoor positioning systems using LED light, our system has the advantages of simple implementation, low cost, and high accuracy. In our system, a single photo diode receives pilot signals from LED panels on the ceiling. Then, the time differences of arrival of these pilot signals are used to estimate the position of the receiver. The system can be employed easily because it does not require embedding any ID to the pilot signal. In the paper, the estimation accuracy of the proposed system is analyzed through the simulation. The causes of estimation error are analyzed, and the estimation accuracy of the system in various conditions is shown by simulations.

Software-defined optical networks (SDONs): a survey

Abstract: This paper gives an overview of software-defined optical networks (SDONs). It explains the general concepts on software-defined networks (SDNs), their relationship with network function virtualization, and also about OpenFlow, which is a pioneer protocol for SDNs. It then explains the benefits and challenges of extending SDNs to multilayer optical networks, including flexible grid and elastic optical networks, and how it compares to generalized multi-protocol label switching for implementing a unified control plane. An overview on the industry and research efforts on SDON standardization and implementation is given next, to bring the reader up to speed with the current state of the art in this field. Finally, the paper outlines the benefits achieved by SDONs for network operators, and also some of the important and relevant research problems that need to be addressed.

Multipath restoration and bitrate squeezing in SDN-based elastic optical networks [Invited]

Abstract: Sliceable bandwidth-variable transponders (SBVTs) enable the adaptation of transmission parameters according to traffic requirements and network constraints. In this study, SBVTs capabilities are evaluated in the context of restoration. In particular, multipath recovery and bitrate squeezing are applied to maximize the amount of restored bitrate, also exploiting limited portions of spectrum resources along multiple routes. An integer linear programming model and heuristic strategy are proposed. A software defined network (SDN) architecture is then introduced to adequately support the SBVT configuration. The SDN architecture is applied to experimentally assess that the overall re-configuration time upon failure detection is included within two seconds, largely dominated by the proprietary control of bandwidth-variable optical cross-connects. Finally, extensive simulation results show the relevant restoration capabilities achieved by the proposed multipath recovery and bitrate squeezing scheme.

Distance-adaptive routing and spectrum assignment in OFDM-based flexible transparent optical networks

Abstract: Orthogonal frequency division multiplexing (OFDM) technology has been recently gaining increasing attention in flexible optical networks due to its significant spectrum efficiency, flexibility, and superior tolerance against impairments. In this paper, we put forward a novel distance-adaptive routing and spectrum assignment algorithm to select the proper modulation format dynamically based on OFDM according to the transmission reach, thereby effectively improving the spectrum utilization. The presented simulation results show that our proposed algorithm achieves significantly improved spectrum efficiency.

Disaster-aware service provisioning with manycasting in cloud networks

Abstract: Cloud services delivered by high-capacity optical datacenter networks are subject to disasters which may cause large-area failures, leading to huge data loss. Survivable service provisioning is crucial to minimize the effects of network/datacenter failures and maintain critical services in case of a disaster. We propose a novel disaster-aware service-provisioning scheme that multiplexes service over multiple paths destined to multiple servers/datacenters with manycasting. Our scheme maintains some bandwidth (i.e., degraded service) after a disaster failure vs. no service at all. We formulate this problem into a mathematical model which turns out to be an Integer Linear Program (ILP), and we provide heuristic optimization approaches as ILP is intractable for large problem instances. Numerical examples show that exploiting manycasting by intelligently selecting destinations in a risk-aware manner for service provisioning offers high level of survivability against link and node failures that may be caused by disasters and post-disaster failures at no extra cost compared to the other survivable schemes.

Disaster-survivable cloud-network mapping

Abstract: Cloud-computing services are provided to consumers through a network of servers and network equipment. Cloud-network (CN) providers virtualize resources [e.g., virtual machine (VM) and virtual network (VN)] for efficient and secure resource allocation. Disasters are one of the worst threats for CNs as they can cause massive disruptions and CN disconnection. A disaster may also induce post-disaster correlated, cascading failures which can disconnect more CNs. Survivable virtual-network embedding (SVNE) approaches have been studied to protect VNs against single physical-link/-node and dual physical-link failures in communication infrastructure, but massive disruptions due to a disaster and their consequences can make SVNE approaches insufficient to guarantee cloud-computing survivability. In this work, we study the problem of survivable CN mapping from disaster. We consider risk assessment, VM backup location, and post-disaster survivability to reduce the risk of failure and probability of CN disconnection and the penalty paid by operators due to loss of capacity. We formulate the proposed approach as an integer linear program and study two scenarios: a natural disaster, e.g., earthquake and a human-made disaster, e.g., weapons-of-mass-destruction attack. Our illustrative examples show that our approach reduces the risk of CN disconnection and penalty up to 90 % compared with a baseline CN mapping approach and increases the CN survivability up to 100 % in both scenarios.

Experimental assessment of in-operation spectrum defragmentation

Abstract: Dynamic operation of flexgrid networks might cause optical spectrum to be divided into fragments, which makes it difficult finding contiguous spectrum of the required width for incoming connection requests, leading thus to an increased blocking probability. To alleviate to some extent that spectrum fragmentation, the central frequency of already established connections can be shifted to create wider contiguous spectrum fragments to be allocated to incoming connections; this procedure is called spectrum defragmentation. In this paper, we propose using the so called applications based network operations (ABNO) architecture, currently under standardization in the IETF, to deal with the defragmentation use case while the network is in operation. A workflow involving several elements in the ABNO architecture is proposed and experimentally assessed in a distributed test bed connecting facilities in three major European cities.

On the benefits of multi-path recovery in flexgrid optical networks

Abstract: We propose a new recovery scheme, called multi-path recovery (MPR), specifically designed for flexgrid-based optical networks. It combines protection and restoration schemes to jointly recover, in part or totally, the bitrate requested by client demands in case of failure. We define the bitrate squeezed recovery optimization (BRASERO) problem to maximize the amount of bitrate which is recovered in case of failure of any single fiber link; a mixed integer linear programming formulation for the BRASERO problem is provided. However, since their exact solutions become impractical when real-sized network and traffic instances are considered, we develop a heuristic algorithm which provides a much better trade-off between optimality and complexity. Exhaustive numerical experiments carried out over realistic network topologies and traffic scenarios show that the efficiency of the proposed MPR scheme approaches that of restoration while providing recovery times as short as protection schemes.

Universal caching model and Markov-based cache analysis for information centric networks

Abstract: Information Centric Networking (ICN) has been proposed as an alternative design for the Internet with a focus on content centric communication rather than host-to-host communication such as telnet or ftp. This requires the data to be cached or stored at intermediate routers to satisfy the future demands for the same contents locally. The existing caching policies are either suboptimal or not suitable for ICN networks. In this paper, we have proposed Universal Caching, a novel caching algorithm, along with a discrete time Markov Chain model based analysis to decide the cache size at a router in ICN networks. The proposed caching algorithm takes into account multiple parameters like distance from the content source, frequency of fetching the content, number of outgoing links at the intermediate router etc. To validate the proposed caching policy and the analytical model, we have conducted extensive simulations using MATLAB. Our simulation results show that the Universal Caching outperforms other caching policies like LRU and FIFO in terms of cache hits, access delay and cost of the link, etc.

Cost-efficient live VM migration based on varying electricity cost in optical cloud networks

Abstract: Information and Communication Technology (ICT) proliferation has led to widespread use of cloud-computing services. ICT constitutes a significant portion of the worldwide energy consumption, and reduction in operating energy expenditures is a high priority for cloud-service providers. Spatial and temporal variations in electricity price can be exploited to reduce the operating cost. One approach is to employ live VM migration for moving, at the right time of the day, virtualized workloads (i.e., VMs) towards those datacenters (DCs) with cheaper energy price. Our approach for cost-efficient VM migration based on varying electricity prices significantly reduces the energy cost to operate cloud services.

Fault tolerance mechanisms for virtual data center architectures

Abstract: A virtual data center (VDC) is a combination of interconnected virtual servers hosted on a physical data center that hosts multiple such VDCs. This enables efficient sharing of the data center's resources while handling dynamic resource requirements of the clients. The SecondNet architecture (Guo et al. in Proceedings of ACMSIGCOMM conference on data communication, Barcelona, pp 63---74, 2009) realizes this VDC concept and includes a centralized VDC resource-mapping (virtual to physical) algorithm. Fault tolerance is an important requirement in data center-based services, in order to increase reliability and availability. In this paper, we propose a fault tolerance mechanism to handle server failures by efficiently migrating the virtual machines (VMs) hosted on the failed server to a new location. Using our mechanism, it is shown that recovery from all the faults is possible, even for a server utilization of 90 %. In order to reduce the impact of server failures on the VDCs hosted in the data center, we then present a new load balancing scheme based on clustering that efficiently allocates the VDCs on the data center. Using this scheme, we were able to reduce the affected number of VMs per server failure by 63 %, in case of a BCube network of size 625 nodes, and by 86 %, in case of a BCube network of size 1,296 nodes.

Bit error rate and reliability analysis of cooperative communication in free-space optical systems

Abstract: We have investigated the performance and reliability improvement of cooperative free-space optical (FSO) communication over single input single output (SISO) system in this paper. The bit error rate (BER) analysis with quadrature phase shift keying (QPSK), gamma---gamma channel model and pointing error has been demonstrated for SISO and cooperative system. The performance improvement with different combining techniques in cooperative system for different channel environments has been shown in the paper. Markov models for reliability analysis of FSO systems in SISO and cooperative communication have been developed. We have obtained significant increase in availability and mean time between failures with cooperative communication over SISO model.

Renewable energy-aware grooming in optical networks

Abstract: The optical layer of a network is the energy-efficient technology to provision high bandwidths for data transport. Unfortunately, occasional electronic processing is unavoidable in current networks. This process is much more energy-consuming than the optical transport. Recent research has already yielded great improvements in terms of energy efficiency. It is, however, observed that increased energy efficiency typically leads to higher overall energy consumption. Therefore, it is imperative to reduce the environmental impact by additional means: maximizing the use of renewable energy. We present an approach to greenhouse gas (GHG) emission-reducing grooming by considering the heterogeneous distribution of fossil and renewable energy sources. We analyze various two-step solutions for the route calculation and lightpath provisioning problem in IP-over-WDM mesh networks. We show that it is possible to reduce GHG emissions at a stable level of energy consumption and improved blocking performance compared to previous energy-efficient solutions.

Analytical model of quality of service scheduling for optical aggregation in data centers

Abstract: Optical switching technologies represent a promising solution for data center interconnection networks to support the increasing bandwidth requirements of current cloud-based applications, while reducing interconnection complexity and energy consumption. Furthermore, the heterogeneity of intra- and inter-data center traffic characteristics requires some form of quality of service management. This paper describes modeling and design aspects of data center optical interconnections with particular emphasis on the aggregation level, where hybrid switching and packet scheduling are jointly applied to effectively implement service differentiation. Priority scheduling of three different service profiles is applied to maximize intra- and inter-data center traffic throughput, while guaranteeing time transparency for delay-sensitive services and zero loss/fixed delay for guaranteed connections. An analytical model is defined and validated to assess loss of real time and throughput of best effort traffic, in asynchronous packet context, when considering best effort traffic saturating the channels of the optical link. The model can also be used to dimension the optical output interface of the aggregation level switch.

Application-aware software-defined EPON access network

Abstract: As bandwidth requirements of access networks continue to increase rapidly, especially due to the growth of streaming traffic, the need for resolving bandwidth contention among competing users and applications becomes more compelling. The proposed Software-Defined Ethernet Passive Optical Network (EPON) architecture utilizes an application-level feedback from the client side (for video users) to the network through a Software-Defined-Network (SDN) controller to achieve better client-and-service-level differentiation in the downstream direction of an EPON access network Numerical results obtained from simulation experiments demonstrate that the proposed architecture with downstream resource allocation for video streaming applications considerably reduce video stalls and increase video buffer level at the client applications leading to better Quality of Experience (QoE) for users along with better client-and-service-level differentiation.

Power consumption reduction through elastic data rate adaptation in survivable multi-layer optical networks

Abstract: Network survivability requires the provisioning of backup resources in order to protect active traffic against any failure scenario. Backup resources, however, can remain unused most of the time while the network is not in failure condition, inducing high power consumption wastage, if fully powered on. In this paper, we highlight the power consumption wastage of the additional resources for survivability in IP/multi-protocol label switching (MPLS) over dense wavelength division multiplexing multi-layer optical networks. We assume MPLS protection switching as the failure recovery mechanism in the network, a solution interesting for current network operators to ensure fast recovery as well as fine-grained recovery treatment per label switched path. Next, we quantitatively show how elastic optical technologies can effectively reduce such a power consumption by dynamically adjusting the data rate of the transponders to the carried amount of traffic.

Optimization for link quality and power consumption of visible light communication system

Abstract: Due to the complexity as well as trade-offs between objectives of the system, it is difficult to design a visible light communication (VLC) system with optimal link quality and power consumption. In this paper, the VLC system design problem is solved by using a multi-objective optimization method. Based on the results of the optimization process, we can determine the parameters to get a VLC system with optimal performance in respect of maximum link quality and minimum power consumption while illumination and other constraints are all satisfied.

Routing, modulation level and spectrum allocation with dynamic modulation level conversion in elastic optical networks

Abstract: Elastic optical network is introduced as a promising technology to provide multi-bitrate-friendly data transmission in the optical layer. Elastic optical networks are based on flexible modulation format conversion, which can make more efficient use of spectrum resources than current fix-grid WDM networks. In this paper, we define the routing, modulation level and spectrum resource allocation (RMLSA) problem and then propose two novel dynamic modulation level conversion (MLC) enabled RMLSA algorithms. Numerical simulations are conducted to compare the performance of the path modulation level conversion (Path-MLC) and link modulation level conversion (Link-MLC) with different MLC thresholds with K-shortest paths RSA in terms of blocking rate, occupied spectrum and the number of MLCs across two topologies. The results verify that the Link-MLC with unlimited MLC achieves the lowest blocking rate and moderate spectrum utilization at the expense of intermediate node modulation conversions in two topologies. Smaller MLC threshold has higher blocking rate and occupied less spectrum resource. The results also suggest that the Path-MLC approach is more resource efficient than the Link-MLC with relatively higher blocking rate, and this method maybe more preferable in the networks with tight budget and/or energy constraints.

Active intra-ONU scheduling with proportional guaranteed bandwidth in long-reach EPONs

Abstract: The unused slot remainder (USR) problem in Ethernet Passive Optical Networks and long-reach Passive Optical Networks (LR-PONs) results in both a lower bandwidth utilization and a greater packet delay. In a previous study by the current group, an Active intra-ONU Scheduling with predictive queue report scheme was proposed for resolving the USR problem by predicting the granted bandwidth in advance based on the arrival traffic estimates of the optical network units (ONUs). However, it was found that the higher bandwidth prediction error in the proposed scheme prevents the network performance from being improved. Accordingly, the present study proposes a non-predictive-based ONU scheduling method designated as Active intra-ONU Scheduling with proportional guaranteed bandwidth (ASPGB) to improve the performance of LR-PONs. In the proposed method, the maximum guaranteed bandwidth of each ONU is adapted dynamically in accordance with the ratio of the ONU traffic load to the overall system load. Importantly, the proposed dynamic bandwidth allocation approach reduces the dependence of the network performance on the granted bandwidth prediction since the maximum guaranteed bandwidth determined by the Optical Line Terminal more closely approaches the actual bandwidth demand of each ONU. To solve the idle time problem arising in the event of an excess bandwidth reallocation, ASPGB is integrated with an improved early allocation (IEA) algorithm (a kind of Just-In-Time scheduling). The simulation results show that the IEA-ASPGB scheme outperforms previously published methods in terms of bandwidth utilization and average packet delay under both balanced and unbalanced traffic load conditions.

Computing blocking probabilities in survivable WDM optical networks

Abstract: One of the most important performance measurements in wavelength-division multiplexing (WDM) networks is the call blocking probability. In this paper, we present an approximate analytical method to evaluate the blocking probabilities in survivable WDM networks with dynamically arriving connection requests. Our approach utilizes the wavelength independence whereby WDM network can be regarded as an aggregation of disjoint single wavelength sub-networks with a common physical topology. In each single wavelength sub-network, we derive the calculation of the blocking probability from an exact analysis. We assume dedicated protection with fixed routing and either first-fit or random wavelength assignment. Simulation results demonstrate the accuracy of the proposed method.

Time-sensitive software-defined networking (Ts-SDN) control architecture for flexi-grid optical networks with data center application

Abstract: Data center interconnected by flexi-grid optical networks is a promising scenario to meet the high burstiness and high bandwidth requirement of data center application, because flexi-grid optical networks can allocate spectral resources for applications in a dynamic, tunable and efficient control manner. Meanwhile, as centralized control architecture, the software-defined networking (SDN) enabled by OpenFlow protocol can provide maximum flexibility for the networks and make a unified control over various resources for the joint optimization of data center and network resources. Time factor is firstly introduced into SDN-based control architecture for flexi-grid optical networks supporting data center application. A traffic model considering time factor is proposed, and a requirement parameter, i.e., bandwidth-period product is adopted for the service requirement measurement. Then, time-sensitive software-defined networking (Ts-SDN)-based control architecture is designed with OpenFlow protocol extension. A novel deadline-driven PCE algorithm is proposed for the deadline-driven service under Ts-SDN-based control architecture, which can complete data center selection, path computation and bandwidth resource allocation. Finally, simulation results shows that our proposed Ts-SDN control architecture and deadline-driven PCE algorithm can improve the application and network performance to a large extent in blocking probability.

Using OpenFlow to provide cut-through switching in MobilityFirst

Abstract: Mobile devices are expected to become the Internet's predominant technology. Current protocols such as TCP/IP were not originally designed with mobility as a key consideration, and therefore underperform under challenging mobile and wireless conditions. MobilityFirst, a clean slate architecture proposal, embraces several key concepts centered around secure identifiers that inherently support mobility and trustworthiness as key requirements of the network architecture. This includes a hop-by-hop segmented data transport based on a globally unique identifier. This allows late and dynamic rebinding of end-point addresses to support mobility. While this provides critical gains in wireless segments, some overheads are incurred even in stable segments such as in the core. Bypassing routing-layer decisions in these cases, with lower layer cut-through forwarding, can improve said gains. In this work, we introduce a general bypass capability within the MobilityFirst architecture that provides better performance and enables both individual and aggregate flow-level traffic control. Furthermore, we present an OpenFlow-based proof-of-concept implementation of the bypass function using layer 2 VLAN tagging. We run experiments on the ORBIT and Global Environment for Network Innovations (GENI) testbeds to evaluate the performance and scalability of the solution. By implementing the bypass functionality, we are able to significantly reduce the number of messages processed by the controller as well as the number of flow rules that need to be pushed into the switches.

Matrix partitioning code family for spectral amplitude coding OCDMA

Abstract: This paper presents a family of newly constructed codes to mitigate the multiple access interference (MAI) and phase-induced intensity noise (PIIN) in spectral amplitude-coding optical code division multiple access systems. The family of newly constructed codes, named matrix portioning (MP) code, is derived from arithmetic sequence, and their cross-correlation is not larger than one. In addition, the weight code can be any number which makes an MP promising code for future optical communication systems. We have also described detailed examples on how to construct this code family. The results reveal that the MP code is effective in reducing the MAI and PIIN, while maintaining a good signal-to-noise ratio and low bit error probability. Simulation results taken from a commercial optical system simulator, Virtual Instrument Photonic $$(\hbox {VPI}^{\mathrm{TM}})$$ ( VPI TM ) , are also demonstrated. The results obtained for MP code have shown significant improvement compared to other schemes that employ flexible cross-correlation, multi diagonal, dynamic cyclic shift, and random diagonal codes. It is shown that, when the effective power is large, the intensity noise specifies as the main factor that deteriorates the system performance. When the effective power is not sufficiently large, thermal and shot noise sources become the main limiting factors and the effect of thermal noise is more influential than that of shot noise.

A study of quality of service in the universal DBA algorithm using a PIC-based EPON testbed

Abstract: Ethernet Passive Optical Network (EPON) has emerged as a promising technology since it offers high bandwidth at a distance that can go up to 20 km. In the upstream EPON transmission, a dynamic bandwidth allocation (DBA) algorithm is needed to avoid collisions and to efficiently allocate the bandwidth. This paper proposes an algorithm called as a Universal DBA (UDBA) algorithm that can support the priority universally in the entire EPON system. A peripheral interface controller (PIC)-based EPON testbed is used to test the algorithm within the mulipoint control protocol environment. For the performance study, we have compared the results achieved using UDBA in terms of delay, throughput, and fairness with two other DBA algorithms. UDBA shows improvements in terms of expedited forwarding, assured forwarding and best effort delay as much as 43.9, 42.6, 20 % over User-oriented Hierarchical Bandwidth Scheduling with Single Cycle (UHSA-S) and 37.5, 20.2, 25.3 % over Modified Smallest Available Report First (MSARF), respectively. Throughput is improved as high as 17.9 % over UHSA-S and 12.8 % over MSARF. In addition, the fairness index of UDBA is higher up to 14 % as compared to UHSA-S and 2.7 % as compared to MSARF.

Provisioning of dynamic traffic in mixed-line-rate optical networks with launch power determination

Abstract: In mixed-line-rate (MLR) networks, different line rates on different wavelengths can coexist on the same fiber. MLR architectures can be built over transparent optical networks, where the transmitted signals remain in the optical domain along the entire path. Along the transparent optical path, a signal experiences various physical layer impairments (PLIs), and its quality degrades as it travels through each optical component. One of the major factors that affect the transmission quality is the launch power of the optical signal. The power must be large enough to ensure noise resiliency at the receiver, but it must be below the limit where fiber nonlinearities distort the signal. Moreover, high launch power is disruptive not only for the actual lightpath itself but also for neighboring lightpaths, and this effect is particularly critical in MLR networks since advanced modulation techniques used for high line rates are highly susceptible to PLIs. In this study, we investigate the problem of determining the appropriate launch power for provisioning of dynamic connection requests in MLR networks. By setting the appropriate launch power for each connection, we aim to maximize the number of established connections. We propose two different heuristics to determine the appropriate launch power of a lightpath. Worst-case best-case average (WBA) is based on optical reach of signal in a transparent optical network. In impairment-aware launch power determination (I-ALPD), current state of the network and impairments are evaluated to determine the launch power. The proposed approaches are practical and can adapt to the needs of network operators. Simulation results show that the performances of the proposed approaches show better results than the existing schemes in terms of blocking probability and bandwidth blocking ratio.

Upgrade-aware virtual infrastructure mapping in software-defined elastic optical networks

Abstract: An emerging use case in software-defined networking is to provide efficient mapping of multiple virtual infrastructures (VIs) simultaneously over the same physical substrate (PS) which can increase the resource utilization of the PS, thus improving its provider's revenue. In this paper, for the first time, we investigate a practical and yet theoretically challenging issue related to dynamic VI mapping in software-defined elastic optical networks while considering the presence of possible upgrade of the VIs and the optical layer constraints, which has not been addressed in any of the existing studies. More specifically, we investigate the following aspects: (1) Which revenue models are appropriate? (2) How to map a new VI request or to upgrade an existing VI to maximize the PS providers revenue? In particular, we study two different revenue models in terms of the incremental pricing policy and the binding pricing policy and propose a number of efficient heuristics to solve the upgrade-aware VI mapping (U-VIM) problem. We also perform comprehensive performance evaluation in different scenario, and the results show that plan-ahead is a desirable strategy when conducting VI mapping in the presence of VI upgrade.

A low-cost alternative scheme to detect a 100 Gbps PM-DQPSK signal

Abstract: We propose and demonstrate a low-cost alternative scheme of direct-detection to detect a 100 Gbps polarization-multiplexed differential quadrature phase-shift keying (PM-DQPSK) signal. The proposed scheme is based on a delay line and a polarization rotator; the phase-shift keying signal is first converted into a polarization shift keying signal. Then, this signal is converted into an intensity-modulated signal by a polarization beam splitter. Finally, the intensity-modulated signal is detected by balanced photodetectors. In order to demonstrate that our proposed receiver is suitable for using as a PM-DQPSK demodulator, a set of simulations have been performed. In addition to testing the sensitivity, the performance under various impairments, including narrow optical filtering, polarization mode dispersion, chromatic dispersion and polarization sensitivity, is analyzed. The simulation results show that our performance receiver is as good as a conventional receiver based on four delay interferometers. Moreover, in comparison with the typical receiver, fewer components are used in our receiver. Hence, implementation is easier, and total cost is reduced. In addition, our receiver can be easily improved to a bit-rate tunable receiver.

Software defined elastic optical networking in temporal, spectral, and spatial domains

Abstract: This paper discusses architecture, protocol, technologies, systems, and networking testbed for software-defined elastic optical networking in temporal, spectral, and spatial domains. By exploiting the progress in elastic optical networking (EON) in temporal and spectral domains utilizing dynamic optical arbitrary waveform generation and measurement technologies, and by extending the EON concept into the spatial domain through the new orbital angular momentum-based spatial division multiplexing, we realize EON exploiting elasticity in temporal, spectral, and spatial domains (3D-EON). Routing, spectral, spatial mode, and modulation format assignment with fragmentation awareness as well as hitless defragmentation for high capacity, high quality of service, and resource-efficient networking will be pursued. OpenFlow-based 3D-EON testbed at UC Davis includes optical supervisory channel with optical performance monitoring for software-defined networking with an adaptive observe-analyze-act cycle.

Survivable virtual topology mapping in IP-over-WDM networks using differential evolution optimization

Abstract: In IP-over-wavelength division multiplexing networks, a virtual topology is placed over the physical topology of the optical network. Given that a simple link failure or a node failure on the physical topology can cause a significant loss of information, an important challenge is to make the routing of the virtual topology on to the physical topology survivable. This problem is known as survivable virtual topology mapping (SVTM) and is known to be an NP-complete problem. So far, this problem has been optimally solved for small instances by the application of integer linear programming and has been sub-optimally solved for more realistic instances by heuristic strategies such as ant colony optimization and genetic algorithms. In this paper, we introduce the application of differential evolution (DE) to solve the SVTM problem and enhancements based on DE are proposed as well. Three algorithms based on DE are developed. The enhanced variants have better convergence rate, get better quality of solutions and require few control parameters. We present the impact of these parameters on the system's performance improvement. Algorithms are evaluated in different test bench optical networks, as NSFnet and USA, demonstrating that the enhanced DE algorithm overcomes the other two, for small instances. The three algorithms reach a 100 survivable mapping for small instances. The three algorithms also find positive survivable mappings and reduce the network wavelength links. Results show the effectiveness and efficiency of the proposed algorithms.

Full-duplex hybrid PON/RoF link with the 10 Gbit/s 16-QAM signal for alternative wired and 60 GHz millimeter-wave wireless accesses

Abstract: A novel full-duplex hybrid access link with 10 Gbit/s 16-ary quadrature amplitude modulation (16-QAM) wired and wireless converged signal is proposed, which can provide PON access or RoF-based wireless access alternately with centralized lightwave source. The converged signal, consisting of the 10 Gbit/s 16-QAM baseband optical signal and two optical local oscillators (OLOs), is generated by central station and can be decomposed in different patterns at remote base station. For the wired PON access, the identical frequency OLO is used to coherently demodulate the 16-QAM signal; while for the RoF-based wireless access, the 16-QAM signal and its parallel polarized OLO are abstracted as optical millimeter wave by a polarization beam splitter; the other OLO is used as the uplink optical carrier to carry wired or wireless uplink signal. Since the three tones come from the same source, they maintain high coherency even after transmitted over fiber link. The proposed hybrid wired/wireless full-duplex fiber link suffers little from fiber chromatic dispersion. These are verified by simulations for both wired and wireless access applications.