Wavelength Division Multiplexing Ring Research Articles

Analysis of Thermal Crosstalk in Photonic Integrated Circuit Using Dynamic Compact Models

Thermal modeling of photonic integrated circuits (PICs) is required for circuit design and the development of thermal control algorithms. In this work, we present a methodology for obtaining a compact dynamic thermal <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$RC$ </tex-math></inline-formula> model of a PIC. PICs are sensitive to thermal coupling, and in this article, it is shown that traditional resistive coupling does not suffice, and a new coupling method is derived. The case study to which the new methodology is applied is a dense wavelength-division multiplexing ring filter with eight channels. With the obtained <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$RC$ </tex-math></inline-formula> model, the computational time is reduced from 5.5 h for finite element simulation to < 1 s for a single-step response. Using the compact model, circuit-level analysis of frequency response is carried out. Because of its high computational efficiency, the compact model opens possibilities for simulating thermal tuning algorithms.

Wide-Sense Nonblocking Multicast in WDM Optical Linear Array and Ring Networks with 3-Length Extension Under Longest Link First Routing

The modern scientific growths in optical networks based on wavelength division multiplexing (WDM) are more attractive to satisfy the high bandwidth requirements of the modern internet infrastructure. Moreover, they potential to satisfy the future bandwidth requirements.WDM optical networks act as the backbone for telecommunication and high-performance communication networks. Multicast communication is the simultaneous transmission of data from one source node to many destination nodes available in the network over wavelength division multiplexing. It is extensively deployed in high performance computing and communication networks. In this article, a linear array and ring networks are extended by directly linking all nodes which are separated by two intermediate nodes with additional fibers which is referred as linear array and ring network with 3-length extension. The wavelength allotment methods are proposed to realize one-to-many communication over wavelength division multiplexing optical linear array and ring with 2-length extension under longest link first routing and the minimum wavelength number needed is determined. The minimum wavelength number needed to support for the extended linear array is reduced approximately by 20% when compared with that of a linear array network and for the extended unidirectional ring is reduced approximately by 25% when compared with that of a unidirectional ring network. And also, for the extended bidirectional ring the minimum wavelength number is reduced approximately by 33% when compared with that of bidirectional ring network.

Wide-sense nonblocking multicast in WRMD WDM optical linear array and ring

Multicast communication is the simultaneous transmission of information from a single source to various destinations. It occurs extensively in telecommunication and advanced computing systems including enterprises operating datacenters. WDM optical networks act as the backbone for telecommunication and high performance networks. Wavelengths are scarce resources in WDM optical networks. Wavelengths usage in a network must be limited to decrease its cost and complexity. Optical linear array and ring networks find widespread application in interconnection networks including LAN and WAN. In this paper, wide-sense nonblocking multicast communication is analyzed in wavelength reusable multi-carrier distributed (WRMD) wavelength division multiplexing (WDM) linear array, unidirectional ring and bidirectional ring networks. The sufficient and necessary condition on the minimum wavelength number required for the network to be wide-sense nonblocking is derived for each of the above network topologies in the presence of a single multi-carrier light source (MCLS). An explicit wavelength allotment technique is also proposed for the above network topologies.

AWG-based WDM ring networks: High-performance and low-cost system designs

Optical packet switching (OPS) ring networks are regarded as being promising solutions for future optical metropolitan area networks. In this paper, we propose novel arrayed-waveguide grating (AWG)-based wavelength division multiplexing (WDM) ring network systems that are aimed at achieving low-cost, scalable, and high-performance systems. By exploiting the cyclic routing properties and spatial wavelength reuse of a passive 2*2 AWG device, we redesign the ring network into a two-subring network, connected through the AWG device. The network is governed by a novel distributed medium access control (MAC) scheme, and we further derive a highly efficient and fair bandwidth allocation in accordance with a quota. A previously proposed experimental optical packet-switched WDM metro-ring network, called HOPSMAN, has shown to have exceptional performance among the OPS ring network studies. We show simulation and analytic results to demonstrate that our proposed system have achieved enhanced performance of the TT (tunable transmitter)-TR (tunable receiver)-based HOPSMAN by 1.5 times but have used only low-cost TT-FR (fixed-tuned receiver) or FT (fixed-tuned transmitter)-FR optical devices. Thus, the proposed networks achieve exceptional network throughput and also greatly reduce system costs.

Investigation of wavelength division multiplexing ring network topology to enhance the system capacity

In this paper, we have investigated the wavelength division multiplexed (WDM) system using ring network topology. This network is used to increase the capacity with eight optical add/drop multiplexers (OADMs) by using dispersion compensating fiber and semiconductor optical amplifier (SOA) to achieve a distance up to 1600km. It is observed that network shows the acceptable results at 15Gbps data rate with 100GHz channel spacing. The OADM nodes are also varied to investigate the network performance in the term of BER and Q-factor.

A secure WDM ring access network employing silicon micro-ring based remote node

A secure and scalable wavelength-division-multiplexing (WDM) ring-based access network is proposed and demonstrated using proof-of-concept experiments. In the remote node (RN), wavelength hopping for specific optical networking unit (ONU) is deployed by using silicon micro-ring resonators (SMR). Using silicon-based devices could be cost-effective for the cost-sensitive access network. Hence the optical physical layer security is introduced. The issues of denial of service (DOS) attacks, eavesdropping and masquerading can be made more difficult in the proposed WDM ring-based access network. Besides, the SMRs with different dropped wavelengths can be cascaded, such that the signals pass through the preceding SMRs can be dropped by a succeeding SMR. This can increase the scalability of the RN for supporting more ONUs for future upgrade. Here, error-free 10Gb/s downlink and 1.25Gb/s uplink transmission are demonstrated to show the feasibility of the proposed network.

Wavelength assignment for all-to-all broadcast in WRMD WDM linear array and ring

This paper proposes a wavelength assignment method for all-to-all broadcast in wavelength reusable multi-carrier distributed (WRMD) wavelength division multiplexing (WDM) linear array and ring networks with wavelength reuse. An expression on the minimum number of wavelengths required to establish all-to-all broadcast is also derived for the networks. It is observed that one carrier regeneration per wavelength significantly reduces the number of wavelengths compared to that without carrier regeneration. The results also show that regenerating carriers more than once has little effect on the required number of wavelengths.

A Packing Problem Approach to Lightpath Assignment in an Optical Ring

We present our work on the dimensioning of a packet-switching wavelength division multiplexing ring in order to reduce its infrastructure (capital expenditure) cost. We study a new all-optical architecture: the packed optical add-drop multiplexer (POADM). We aim to minimize the overall cost of the network by reducing the number of indispensable devices in the nodes and the number of required wavelengths. We formalize the packing problems underlying the ring dimensioning. The elements to be packed are made up of transmissions that share the same destination. We assume that elements can be cut before being packed into boxes. We furnish a complete theoretical analysis of the complexity and approximability of these problems. We define also several measures of quality for a cut and provide an optimal cutting strategy, according to these measures. Our subsequent contribution is a heuristic solution that solves the bi-criteria packing problem (the number of boxes and the number of cuts are minimized simultaneously). The exhaustive numerical results of this heuristic algorithm come next. We rely on our optimal cutting strategy to appraise the efficiency of other strategies. We also adapt the only existing POADM dimensioning algorithm, more restrictive than ours, and we confront it with our solution. The analysis of results allows us to provide network design guidelines to perform the dimensioning in the most efficient way.

Scheduling light-trails on WDM rings

We consider the problem of scheduling communication on optical WDM (wavelength division multiplexing) networks using the light-trails technology. We seek to design scheduling algorithms such that the given transmission requests can be scheduled using a minimum number of wavelengths (optical channels). We provide algorithms and close lower bounds for two versions of the problem on an n processor linear array/ring network. In the stationary version, the pattern of transmissions (given) is assumed to not change over time. For this, a simple lower bound is c, the congestion or the maximum total traffic required to pass through any link. We give an algorithm that schedules the transmissions using O(c+logn) wavelengths. We also show a pattern for which Ω(c+logn/loglogn) wavelengths are needed. In the on-line version, the transmissions arrive and depart dynamically, and must be scheduled without upsetting the previously scheduled transmissions. For this case we give an on-line algorithm which has competitive ratio Θ(logn). We show that this is optimal in the sense that every on-line algorithm must have competitive ratio Ω(logn). We also give an algorithm that appears to do well in simulations (for the classes of traffic we consider), but which has competitive ratio between Ω(log2n/loglogn) and O(log2n). We present detailed simulations of both our algorithms.

Performance evaluation of survivable WDM based SANs in a metro ring network

Storage area networks (SANs) are an essential part of enterprise computing today. There is no comprehensive business continuity plan without SANs in the picture. This paper proposes and evaluates network survivability of optical paths in wavelength division multiplexing (WDM) based storage area networks in a metro ring network. The paper begins with a background on network survivability in metro WDM ring network. Subsequently, the network and node architectures along with their medium access control (MAC) protocols are described. In this work, one link failure (a single cable cut) in metro WDM based SANs in a ring network architecture is considered. Performance evaluation for network survivability in metro WDM SAN is carried out by means of discrete-event computer simulation. Network throughput and packet delay are investigated. The network performance is evaluated for asymmetric (unbalanced) traffic scenarios under Poisson and self-similar traffic.

Fast Exact ILP Decompositions for Ring RWA

Wavelength division multiplexing rings are now capable of supporting more than 100 wavelengths over a single fiber. Conventional link and path formulations for the routing and wavelength assignment problem are inefficient due to the inherent symmetry in wavelength assignment and the fact that the problem size increases fast with the number of wavelengths. Although a formulation based on maximal independent sets (MIS) does not have these drawbacks, it suffers from exponential growth in the number of variables with increasing network size. We develop a new ILP (integer linear program) formulation based on the key idea of partitioning the path set and representing the MIS in the original network using the independent sets calculated in each of these partitions. This exact decomposition trades off the number of variables with the number of constraints and, as a result, achieves a much better scalability in terms of network dimension. Numerical results on ring networks of various sizes demonstrate that this new ILP decomposition achieves a decrease of several orders of magnitude in running time compared to existing formulations. Our main contribution is a novel and extremely fast technique for obtaining, in a few seconds using commodity CPUs, optimal solutions to instances of maximum size SONET rings with any number of wavelengths; such instances cannot be tackled with classical formulations without vast investments in computational resources and time.

Wavelength Assignment in Multi-Carrier Distributed Optical Ring Networks With Wavelength Reuse

This paper investigates the problem of wavelength assignment in wavelength reusable multi-carrier distributed (WRMD) wavelength-division-multiplexing (WDM) ring networks. In conventional WDM ring networks, each edge node (EN) has its own light sources, and optical channels, called lightpaths, are established by using optical carriers generated from laser diodes (LDs) at the source EN. However, such networks will suffer from the need for complicated wavelength management (e.g., monitoring LDs, avoiding wavelength collision) in the future since each EN requires a large number of LDs to deal with the exponential increase in traffic. On the other hand, a WRMD ring network overcomes this problem. In this network, lightpaths between source and destination ENs are established by using carriers generated from a centralized multi-carrier light source. Moreover, the carrier regeneration technique is applied for the purpose of reducing the number of wavelengths used for lightpath establishment. Although optical carrier regeneration reduces the number of wavelengths, the quality of the regenerated carrier is slightly degraded after carrier regeneration. Therefore, in the WRMD network, the allowable number of carrier regenerations per wavelength must be limited in order to avoid communication error. This paper formulates the wavelength assignment problem, minimizing the number of wavelengths needed to establish all requested lightpaths, as the vertex coloring problem, and then an integer linear programming (ILP) solution is provided. Since ILP problems are non-deterministic polynomial-time- (NP-) complete, a heuristic algorithm is developed. Numerical results indicate that our developed algorithm performs well in our test cases. It is observed that one and two carrier regenerations per wavelength reduce the number of wavelengths for lightpath establishment by approximately 50% and 60%, respectively, compared to that without carrier regeneration. The results also show that regenerating carriers more than two times per wavelength has little effect on the required number of wavelengths regardless of the number of ENs.

Performance analysis of a metro WDM ring networks with variable-length packets under symmetric and asymmetric traffic

In this paper, we discuss and evaluate two proposed metro wavelength division multiplexing (WDM) ring network architectures for variable-length packet traffic in storage area networks (SANs) settings. The paper begins with a brief review of the relevant architectures and protocols in the literature. Subsequently, the network architectures along with their medium access control (MAC) protocols are described. Performance of the two network architectures is studied by means of computer simulation in terms of their queuing delay, node throughput and proportion of packets dropped. The network performance is evaluated under symmetric and asymmetric traffic scenarios with Poisson and self-similar traffic.

Analysis of delay mean and variance of collision-free WDM rings with segment recirculation of blocked traffic

In Tunable-Transmitter Fixed-Receiver (TT-FR)-based Wavelength Division Multiplexed (WDM) ring topologies, each node is provided with a dedicated wavelength (home channel) for reception, which must be shared by the upstream nodes willing to communicate with it. Thus, to avoid channel collisions, it is necessary to define a Medium Access Control (MAC) mechanism that arbitrates access to a given destination wavelength. This work proposes and analyses a simple MAC mechanism that avoids channel collisions by recirculating traffic on the upstream ring segment where congestion was detected. Essentially, whenever a given node has got any traffic to transmit, it must first block access to in-transit traffic, which is reflected back to the upstream node over a second optical fibre. Such blocked traffic is given a second chance to pass through the congested node after a round segment delay, thus making use of the ring topology as buffering units. This work analyses the performance operation of such a MAC protocol under two policies applied to recirculated traffic: (1) recirculation bypass and (2) recirculation store-and-forward.

All-optical code routing in interconnected optical CDMA and WDM ring networks

We propose an all-optical hybrid network composed of optical code division multiple access (CDMA) rings interconnecting through a reconfigurable wavelength division multiplexing (WDM) metro area ring. This network retains the advantages of both the optical CDMA and WDM techniques, including asynchronous access and differentiated quality of service, while removing the hard limit on the number of subscribers and increasing network flexibility. The all-optical network is enabled by using nonlinear optical loop mirrors in an add/drop router (ADR) that performs code conversion, dropping, and switching asynchronously. We experimentally demonstrate the functionalities of the ADR in the proposed scheme asynchronously and obtain error-free performance. The bit-error rate measurements show acceptable power penalties for different code routes.

Performance Evaluation of Transmission Algorithms for CSMA/ID WDM Ring Networks

As data traffic increase rapidly, IP over WDM (Wavelength Division Multiplexing) transport will replace conventional SONET transport in current metropolitan area networks. Such networks will require new MAC protocols to efficiently share network bandwidth among multiple network nodes. This research project describes and evaluates a novel Carrier Sense Multiple Access with Idle Detection (CSMA/ID) MAC protocols for IP over WDM ring networks. The paper focuses on the influence of performance for the packet scheduling algorithms included FIFO, OPF_CA and OPF_CF. An analytical model is developed to evaluate the performance of the protocol, with simulation results showing good network efficiency and will be an excellent candidate for next-generation metro networks.

Storage and Mirroring in Single and Dual Section Metro WDM Rings under Different Traffic Scenarios

This paper introduces a novel data mirroring technique for storage area networks (SANs) in a metropolitan wavelength division multiplexing ( WDM) ring scenario. Sectioning links are introduced to the ring to help deal with the hot node (SAN node on ring) scenarios created by the SANs and their mirrors. Two network architectures are studied: The first architecture accommodates conventional access nodes and a single SAN and its mirror, the latter connected through a sectioning link. The other architecture accommodates conventional access nodes and two pairs of SANs and their mirrors with a sectioning link connecting each pair. Simulation is carried out to evaluate the performance of both architectures under the proposed mirroring technique for a 24 node architecture with 1 Gb/s access node rate and 5 Gb/s SAN node rate and under two different traffic models– Poisson and selfsimilar . In addition to the fixed-size (FS) slot scheme, performance is evaluated under two different slot schemes accommodating variable size packet traffic — variable-size (VS) and super-size (SS) slot schemes. Simulation Results of average node throughput and queuing delay are presented and analyzed.

Reducing Network Cost of Many-to-Many Communication in Unidirectional WDM Rings With Network Coding

In this paper, we address the problem of traffic grooming in wavelength-division multiplexing rings with all-to-all and its generalization to many-to-many service by using network coding. We consider minimizing the number of line terminating equipment on two types of unidirectional rings, namely, single-hub and unhubbed rings, as our objective. In single-hub rings, we investigate the minimum cost provisioning of uniform all-to-all traffic in two cases: where network coding is used to linearly combine data, and where it is not used and data are transmitted without coding. We generalize the service mode to many-to-many and evaluate the cost of provisioning. In unhubbed ring, we propose a multihub approach to obtain the minimum cost provisioning in the case of all-to-all and many-to-many traffic. In each type of ring topology, two network scenarios are considered: first, the distinct communication groups in the ring are node-disjoint, and second, the different groups may have common member nodes. From our numerical results, we find that under many-to-many traffic pattern for both scenarios, network coding can reduce the network cost by 10%-20% in single-hub rings and 1%-5% in unhubbed rings in both network scenarios.

Single-Fiber Access/Metro WDM Ring Architecture for Asymmetric Traffic Applications in Next Generation Networks

The next generation network (NGN) and the speed-up of access lines will sharply increase the demand for one-way applications such as internet protocol television (IP TV) and video on demand (VOD). One-way applications make the downlink bandwidth much larger than the uplink bandwidth. Asymmetric traffic is best supported by using different numbers of wavelengths in the uplink and downlink, which presumes the use of a wavelength division multiplexing (WDM) network. Unfortunately, the existing 2- or 4-fiber ring network architecture is symmetric, and so it cannot efficiently accommodate asymmetric paths. This paper proposes a novel 1-fiber WDM protection ring that offers a cost-effective optical network architecture for asymmetric traffic as well as symmetric traffic. It also proposes a new 1:1 protection switching scheme and automatic protection switching (APS) control protocol that can reduce capital expenditures for optical-electro-optical termination cards and provide nonrevertive protection switching with extra traffic and APS with end-to-end supervision including optical switching fabrics. Moreover, this paper shows that the proposed wavelength switching scheme offers much better network survivability after multiple wavelength failures than the existing bidirectional switching scheme can offer.

A node configuration algorithm with bandwidth bottleneck resolution for WDM ring networks

The wavelength-division multiplexing (WDM) technology has been extensively studied and actually deployed as a key technology to solve global information explosions by multiplexing plural signal paths using different wavelengths into one optical fiber. Among WDM-based network architectures, this article focuses on a double-ring one for a next-generation metropolitan area network (MAN), where each node is normally equipped with two pairs of fast-tunable transmitters and wavelength-fixed receivers (TT-FR) as interface to two fibers. To enhance the network performance, additional transmitters/receivers at nodes and receiver wavelengths should be assigned optimally, so that the bandwidth bottleneck can be resolved both on nodes and fiber links. This article formulates this node configuration problem with bandwidth bottleneck resolution as a combinatorial optimization problem, and proves the NP-completeness of its decision version. Then, it presents the two-phase heuristic algorithm composed of a greedy method and a variable depth search (VDS) method. Our algorithm is evaluated through extensive network simulations, where the results support the effectiveness of this joint assignment approach.