Feedback-Based Channel Frequency Optimization in Superchannels

Superchannels leverage the flexibility of elastic optical networks and pave the way to higher capacity channels in space division multiplexing (SDM) networks. A superchannel consists of subchannels to which continuous spectral grid slots are assigned. To guarantee superchannel operation, we need to account for soft failures, e.g., laser drifts causing interference between subchannels, wavelength-dependent performance variations, and filter misalignments affecting the edge subchannels. This is achieved by reserving spectral guardband between subchannels or by employing a lower modulation format. We propose a process that dynamically retunes the subchannel transmitter (TX) lasers to compensate for soft failures during operation and optimizes the total capacity or the minimum subchannel quality of transmission (QoT) performance. We use an iterative stochastic subgradient method that at each iteration probes the network and leverages monitoring information, particularly subchannels signal-to-noise ratio (SNR) values, to optimize the TX frequencies. Our results indicate that our proposed method always approaches the optima found with an exhaustive search technique, unsuitable for operating networks, irrespective of the subchannel number, modulation format, roll-off factor, filters bandwidth, and starting frequencies. Considering a four-subchannel superchannel, the proposed method achieves 2.47 dB and 3.73 dB improvements for a typical soft failure of +/- 2 GHz subchannel frequency drifts around the optimum, for the two examined objectives

Characterization of Multi-Core Fiber Group Delay with Correlation OTDR and Modulation Phase Shift Methods

Using a Correlation-OTDR and a modulation phase shift method we characterized four multi-core fibers. The results show that the differential delay depends on the position of the core in the fiber and varies with temperature.Comment: This work has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 762055 (BlueSpace Project

Modular SDN-enabled S-BVT Adopting Widely Tunable MEMS VCSEL for Flexible/Elastic Optical Metro Networks

We propose an SDN-enabled S-BVT adopting directly-modulated tunable VCSEL with direct-detection for optical metro networks and spectrum defragmentation. We experimentally assess it over different network paths up to 185km and in presence of adjacent slices

Recent Trends and Considerations for High Speed Data in Chips and System Interconnects

This paper discusses key issues related to the design of large processing volume chip architectures and high speed system interconnects. Design methodologies and techniques are discussed, where recent trends and considerations are highlighted

Taburan, kepelbagaian dan sepsis kelawar di tiga kawasan habitat vegetasi di hutan Sukau, Sandakan , Sabah

This research was carried out with the aim to record and compare information on the diversity, distribution and abundance of bat species at three different habitats of Sukau Rainforest. These were the primary forest, oil palm plantation and village area. Sampling was conducted for six days at each habitat using three mist net and a sweep net. A total of248 individuals of 15 species were caught in this study. Results showed that the village area has the highest bat diversity (H'=1.9) followed by primary forest (H'=I.4). The oil palm plantation area recorded the lowest diversity (H'=O.9). The presence of Sungai Kinabatangan nearby, the close proximity of Gua Keruak, the presence of human settlements and the mixed vegetation were identified to contribute to the high diversity at the village area. It was expected that the primary forest area has higher bat diversity as compared to the oil palm plantation area due to the abundance of food available for bats at this forest and the presence of undisturbed roosting sites. In contrast, the lower diversity recorded at the oil palm plantation was probably because of the less abundance of food available for bats particularly nocturnal insects which is the main diet of Microchiropterans. However, the occurrence of Megachiropterans was high at the oil palm plantation area which is probably because of the presence of oil palm fruits. It can be concluded from this study that there is a difference in terms of bat diversity and this maybe correlated with variation of the vegetations whereby suitability and availability of food and roosting sites play an important role

Experimental Demonstration of Extended 5G Digital Fronthaul Over a Partially-Disaggregated WDM/SDM Network

© 2021 IEEE. Personal use of this material is permitted. Permissíon from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertisíng or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.[EN] We experimentally demonstrate a 5G digital fronthaul network that relies on multi-adaptive bandwidth/bitrate variable transceivers (BVTs) and an autonomic software-defined networking (SDN) control system for partially-disaggregated wavelength division multiplexing (WDM)/space division multiplexing (SDM). Transmission of 256-QAM 760.32 MHz orthogonal frequency-division multiplexing (OFDM) radio signal is performed, with a total radio transmission capacity of 5.667 Gb/s. Digitized signal samples are carried as a 22.25 Gb/s digitized radio-over-fiber (DRoF) data stream and transmitted over a WDM/SDM infrastructure including 40-wavelength 100-GHz arrayed waveguide gratings (AWGs) and 19-core fiber. The autonomic SDN controller deploys a control loop for the multi-adaptive OFDM-based BVTs that monitors the per-subcarrier signal to noise ratio (SNR) and assigns the optimal constellation based on the actual signal degradation. An error vector magnitude (EVM) below the targeted 2.1% is achieved while setting up connections in less than 5 s.This work was supported in part by the EC H2020 BLUESPACE Project under Grant 762055 and in part by the Spanish MICINN AURORAS Project under Grant RTI2018-099178.Fabrega, JM.; Múñoz, R.; Nadal, L.; Manso, C.; Svaluto Moreolo, M.; Vilalta, R.; Martínez, R.... (2021). Experimental Demonstration of Extended 5G Digital Fronthaul Over a Partially-Disaggregated WDM/SDM Network. IEEE Journal on Selected Areas in Communications. 39(9):2804-2815. https://doi.org/10.1109/JSAC.2021.3064645S2804281539

On the Filter Narrowing Issues in Elastic Optical Networks

This paper describes the problematic filter narrowing effect in the context of next-generation elastic optical networks. First, three possible scenarios are introduced: the transition from an actual fixed-grid to a flexigrid network, the generic full flexi-grid network, and a proposal for a filterless optical network. Next, we investigate different transmission techniques and evaluate the penalty introduced by the filtering effect when considering Nyquist wavelength division multiplexing, single side-band direct-detection orthogonal frequency division multiplexing, and symbol-rate variable dual polarization quadrature amplitude modulation. Also, different approaches to compensate for the filter narrowing effect are discussed. Results show that the specific needs per each scenario can be fulfilled by the aforementioned technologies and techniques or a combination of them, when balancing performance, network reach, and cost

Control orchestration protocol:unified transport API for distributed cloud and network orchestration

In the context of the fifth generation of mobile technology (5G), multiple technologies will converge into a unified end-to-end system. For this purpose, software defined networking (SDN) is proposed, as the control paradigm will integrate all network segments and heterogeneous optical and wireless network technologies together with massive storage and computing infrastructures. The control orchestration protocol is presented as a unified transport application programming interface solution for joint cloud/network orchestration, allowing interworking of heterogeneous control planes to provide provisioning and recovery of quality of service (QoS)-aware end-to-end services. End-to-end QoS is guaranteed by provisioning and restoration schemes, which are proposed for optical circuit/packet switching restoration by means of signal monitoring and adaptive modulation and adaptive route control, respectively. The proposed solution is experimentally demonstrated in an international multi-partner test bed, which consists of a multi-domain transport network comprising optical circuit switching and optical packet switching domains controlled by SDN/OpenFlow and Generalized Multiprotocol Label Switching (GMPLS) control planes and a distributed cloud infrastructure. The results show the dynamic provisioning of IT and network resources and recovery capabilities of the architecture.Grant numbers : This work was partially supported by the Spanish MINECO project DESTELLO (TEC2015-69256-R)