Field Of Optical Networks Research Articles

An architecture to improve performance of software-defined optical networks

The software-defined optical network (SDON) is a revolutionary approach in the field of optical networks. The separation of the control plane and data plane in software-defined networking (SDN) provides enhanced security and simplified network administration. Nevertheless, performance and control plane scalability are significant issues in SDN. SDN performance can be evaluated using parameters such as burst loss, delay, channel occupancy, packet loss, throughput, and average response time. The number of messages exchanged between the data plane and the control plane is used as a metric to determine controller scalability. As the network load increases, the controller experiences a higher flow of messages. It causes delay and burst loss in transmitting the burst. Occasionally, bursts exceed the capacity of the fixed-sized burstifier and are discarded because it takes a long time to identify a suitable route for the burst. Hence, it is essential to minimize the volume of messages exchanged between the control plane and the data plane to improve performance and controller scalability. In this paper, we propose a scalable SDN optical network architecture that minimizes the number of messages exchanged between the data plane and the control plane. We proposed mechanisms like channel reservation, transmission cycles, and guard time between cycles to enhance both the speed and the quality of burst transmission. Prior to transmission, resources or channels are allocated to bursts to minimize the possibility of burst collision and loss. The data plane comprises an optical burst switching (OBS) network, and the flow table entries are periodically updated to minimize inter-plane communication. We perform simulations to evaluate and compare the performance of the proposed architecture with the existing state-of-the-art architecture reported in the literature. The proposed architecture performs better than the existing state-of-the-art in terms of metrics including burst loss, delay, channel occupancy, packet loss, throughput, average response time, and reduction in the number of messages exchanged between the data plane and the control plane. Experimental results indicate a 41% reduction in mean burst loss probability and a 40.5% reduction in mean burst sending delay compared to existing architectures. Additionally, 42.1% fewer messages are exchanged between the control plane and the data plane compared to the number of exchanged messages in existing architectures.

Machine Learning-Based Routing and Wavelength Assignment in Software-Defined Optical Networks

Recently, machine learning (ML) has attracted the attention of both researchers and practitioners to address several issues in the optical networking field. This trend has been mainly driven by the huge amount of available data (i.e., signal quality indicators, network alarms, etc.) and to the large number of optimization parameters which feature current optical networks (such as, modulation format, lightpath routes, transport wavelength, etc.). In this paper, we leverage the techniques from the ML discipline to efficiently accomplish the routing and wavelength assignment (RWA) for an input traffic matrix in an optical WDM network. Numerical results show that near-optimal RWA can be obtained with our approach, while reducing computational time up to 93% in comparison to a traditional optimization approach based on integer linear programming. Moreover, to further demonstrate the effectiveness of our approach, we deployed the ML classifier into an ONOS-based software defined optical network laboratory testbed, where we evaluate the performance of the overall RWA process in terms of computational time.

GA-BASED DYNAMIC ROUTING IN WDM OPTICAL NETWORKS

The enormous increase in online content and the requirement of providing universal access to broadband Internet services is already stretching the capabilities of current technologies to their limit. New applications require networks with well-known and predictable characteristics and behavior. Advances in optical networks, together with the rapid rising demand for network bandwidth, are fueling an increasing amount of research in the field of optical networks. Optical communication has become a promising networking choice to meet increasing demand on bandwidth. Some of the emerging bandwidth-intensive computing and communication applications such as data browsing on the web, video conferencing, e-commerce, high-definition video/audio on-demand processing, data mining, database and decision-support transactions etc. The objective of this paper is to minimize the number of wavelengths, converters or other cost parameters. For this the network path should be an optimized one. This problem can be formulated as a mixed integer linear program, which is NP-complete. Performance has been evaluated with three different networks, a small, medium and large sized network with 6-node, 10-node and 14-node networks, respectively. Analysis shows that the Genetic Algorithm (GA) based method provides an optimized route with significantly less blocking probability than the normal cases.

Power-efficient RWA in dynamic WDM optical networks considering different connection holding times

The challenges imposed by environmental issues, such as global warming and the energy crisis, are demanding more responsible energy usage, including in the optical networking field. In optical transmission networks, most of the electrical power is consumed by the optical-electrical-optical conversion in optical repeaters. Modern optical network control plane technologies allow idle optical repeaters to be put into a low-power sleep mode. Inspired by this, we propose a novel power-efficient routing and wavelength assignment (RWA) algorithm, called HTAPE. The HTAPE algorithm exploits the knowledge of the connection holding times to minimize the number of optical repeaters in the active mode, and hence reduce the total electricity consumption of the optical network. We test the new algorithm on the typical CERNET and USNET networks. Compared with traditional RWA algorithms without holding-time-awareness, it is observed that the HTAPE algorithm yields significant reductions in power consumption.

Gridless optical networking field trial: flexible spectrum switching, defragmentation and transport of 10G/40G/100G/555G over 620-km field fiber

We present results from the first gridless networking field trial with flexible spectrum switching nodes and 620 km of installed fibre links. Signals at 10G, 12.25G, 42.7G, DP-QPSK 40G, DP-QPSK 100G and 555G are generated, successfully transported and switched using flexible, custom spectrum allocation per channel. Spectrum defragmentation is demonstrated using integrated SOA-MZI wavelength converters. Results show error-free end-to-end performance (BER<1e-9) for the OOK channels and good pre-FEC BER performance with sufficient margin to FEC limit for the 40G and 100G coherent channels as well as for the 555G super-channel.

Perfect shuffle transform based on a microblazed grating array

Based on the theory of information optics and binary optics a new method of achieving a perfect shuffle transform is reported by using a microblazed grating array. The field distribution at the output plane and the equations of period of the microblazed grating array are obtained. According to these equations, the technical design and fabricated parameters are accomplished and proposed. It is shown that the theoretical analysis accords well with the practical application in a sequence of fabrications and testing experiments. The conclusions of the theoretical analysis and the experiment are important and will significantly guide the realization of optical switching and optical interconnection by using micro-optical diffractive elements. It is proved that the micro-optical elements will play an important role in the field of optical networks and optical computing.

Optical network research and development in European Community programs: from RACE to ACTS

The European Union programs of cooperative research and development in telecommunications aim to ensure the realization of the future information society. The RACE Program (1988 to 1995) made an important contribution to the development of advanced optical communications. The current ACTS Program has an increased focus on field trials and networking. ACTS projects in the field of optical networks are studying multiwavelength network concepts, customer access, high-speed multiplexing and transport, and components and subsystems.