Optimal Regenerator Placement for Dedicated Path Protection in Impairment-Aware WDM Networks

Building resilient Wavelength Division Multiplexed (WDM) optical networks is an important area of research. This thesis deals with the design of reliable WDM networks where physical layer impairments are taken into account. This research addresses both the regenerator placement problem (RPP) and the routing with regenerator problem (RRP) in impairment-aware WDM networks, using dedicated path protection. Both the problems have been tackled using linear Integer formulations which can be implemented, using a solver such as the CPLEX. For solving RPP, two solutions have been proposed - i) a formulation that gives optimal solutions which works only for small networks, and ii) a highly effective heuristic which given an optimal solution in 97.5 to 99% of cases for networks having a size up to 60 nodes

A Heuristic Approach for Impairment-Aware Static RWA in WDM Translucent Networks

In a Wavelength Division Multiplexed (WDM) optical network, data is communicated using modulated optical signals. In a WDM network, corresponding to each connec- tion request, a lightpath is to route the optical signals through the network. During its propagation through the optical network the quality of an optical signal degrades due to various physical phenomena. Regenerators are devices to restore the quality of optical signals in WDM networks. Our objective is to propose a new heuristic to carry out Routing and Wavelength Assignment (RWA), taking into consideration the physical layer impairments. For a given set of source-destination pairs and the topology of a network, this heuristic will carry out RWA using a minimum number of regenerators, while maintaining a desired level of quality of transmission

Multi-Band Optical Networks Capacity, Energy, and Techno-Economic Assessment

L'abstract è presente nell'allegato / the abstract is in the attachmen

Path Protection in Translucent WDM Optical Networks

Optical noise, chromatic dispersion, nonlinear effects, polarization mode dispersion (PMD) and cross-talk cause the quality of an optical signal to degrade as it propagates through the fibers in wavelength division multiplexed (WDM) optical networks. In a translucent network, regenerators are placed ay appropriate intervals to carry out 3R regeneration (re-amplify, re-shape and re-time). Translucent WDM networks are receiving attention as long-haul back bone networks. One important aspect of such networks that has not received attention is the possibility of cycles in the path of a translucent network. This research studies how we implement path protection in translucent networks, considering the possibility of cycles. We are developing a new scheme for dynamic lightpath allocation using the idea of shared path protection. We propose to study the performance of the scheme using a number of well known networks

Impairment-Aware Dynamic Routing and Wavelength Assignment in Translucent Optical WDM Networks

Routing and wavelength assignment (RWA) is a widely discussed design problem in the optical networks literature. Physical layer impairments (PLI) degrade the quality of transmission (QOT) of a propagating optical signal inside the optical fiber and they have a significant impact on the RWA process. 3R regeneration, which is based on the expensive optical-to-electronic-to-optical (OEO) conversion technology, is a popularly used technique to restore the degraded QOT of an optical signal. In order to minimize both capital and operational costs, it is highly desirable to use a translucent optical network, in which the 3R regenerators are sparsely yet strategically placed. This thesis presents a novel impairment-aware RWA approach, called best first search RWA (BFS-RWA), for dynamic connection requests, in a translucent optical network. BFS-RWA is based on the A* best first search algorithm and guarantees an optimal solution (i.e. using the least possible number of regenerators)

Optimization of integrated water and multiregenerator membrane systems

A thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy (Chemical Engineering), September 2017Water and energy are key resources in the process industry. The water-energy nexus considers the interdependence of water and energy resources and their effect on the environment. The increasing awareness of environmental regulations has heightened the need for process integration techniques that are environmentally benign and economically feasible. Process integration techniques within water network synthesis require a holistic approach for the sustainable use of water through reuse and recycle and regeneration reuse and recycle. Conventional methods for water minimisation through water network synthesis often use the “black-box” approach to represent the performance of the regenerators. The degree of contaminant removal and cost of regeneration are represented by linear functions. This, therefore, leads to suboptimal operating conditions and inaccurate cost representation of the regeneration units. This work proposes a robust water network superstructure optimisation approach for the synthesis of a multi-regenerator network for the simultaneous minimisation of water and energy. Two types of membrane regenerators are considered for this work, namely, electrodialysis and reverse osmosis. Detailed models of the regeneration units are embedded into the water network superstructure optimisation model to simultaneously minimise water, energy, operating and capital costs. The presence of continuous and integer variables, as well as nonlinear constraints renders the problem a mixed integer nonlinear program (MINLP). The developed model is applied to two illustrative examples involving a single contaminant and multiple contaminants and one industrial case study of a power utility plant involving a single contaminant to demonstrate its applicability. The application of the model to the single contaminant illustrative example lead to a 43.7% freshwater reduction, 50.9% decrease in wastewater generation and 46% savings in total water network cost. The multi-contaminant illustrative example showed 11.6% freshwater savings, 15.3% wastewater reduction, 57.3% savings in regeneration and energy cost compared to the water network superstructure with “black-box” regeneration model. The industrial case study showed a savings of up to 18.7% freshwater consumption, 82.4% wastewater reduction and up to 17% savings on total water network cost.XL201

Application of advanced on-board processing concepts to future satellite communications systems: Bibliography

Abstracts are presented of a literature survey of reports concerning the application of signal processing concepts. Approximately 300 references are included

Fully-photonic digital radio over fibre for future super-broadband access network applications

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel UniversityIn this thesis a Fully-Photonic DRoF (FP-DRoF) system is proposed for deploying of future super-broadband access networks. Digital Radio over Fibre (DRoF) is more independent of the fibre network impairments and the length of fibre than the ARoF link. In order for fully optical deployment of the signal conversion techniques in the FP-DRoF architecture, two key components an Analogue-to-Digital Converter (ADC) and a Digital-to-Analogue Converter (DAC)) for data conversion are designed and their performance are investigated whereas the physical functionality is evaluated. The system simulation results of the proposed pipelined Photonic ADC (PADC) show that the PADC has 10 GHz bandwidth around 60 GHz of sampling rate. Furthermore, by changing the bandwidth of the optical bandpass filter, switching to another band of sampling frequency provides optimised performance condition of the PADC. The PADC has low changes on the Effective Number of Bit (ENOB) response versus analogue RF input from 1 GHz up to 22 GHz for 60 GHz sampling frequency. The proposed 8-Bit pipelined PADC performance in terms of ENOB is evaluated at 60 Gigasample/s which is about 4.1. Recently, different methods have been reported by researchers to implement Photonic DACs (PDACs), but their aim was to convert digital electrical signals to the corresponding analogue signal by assisting the optical techniques. In this thesis, a Binary Weighted PDAC (BW-PDAC) is proposed. In this BW-PDAC, optical digital signals are fully optically converted to an analogue signal. The spurious free dynamic range at the output of the PDAC in a back-to-back deployment of the PADC and the PDAC was 26.6 dBc. For further improvement in the system performance, a 3R (Retiming, Reshaping and Reamplifying) regeneration system is proposed in this thesis. Simulation results show that for an ultrashort RZ pulse with a 5% duty cycle at 65 Gbit/s using the proposed 3R regeneration system on a link reduces rms timing jitter by 90% while the regenerated pulse eye opening height is improved by 65%. Finally, in this thesis the proposed FP-DRoF functionality is evaluated whereas its performance is investigated through a dedicated and shared fibre links. The simulation results show (in the case of low level signal to noise ratio, in comparison with ARoF through a dedicated fibre link) that the FP-DRoF has better BER performance than the ARoF in the order of 10-20. Furthermore, in order to realize a BER about 10-25 for the ARoF, the power penalty is about 4 dBm higher than the FP-DRoF link. The simulation results demonstrate that by considering 0.2 dB/km attenuation of a standard single mode fibre, the dedicated fibre length for the FP-DRoF link can be increased to about 20 km more than the ARoF link. Moreover, for performance assessment of the proposed FP-DRoF in a shared fibre link, the BER of the FP-DRoF link is about 10-10 magnitude less than the ARoF link for -19 dBm launched power into the fibre and the power penalty of the ARoF system is 10 dBm more than the FP-DRoF link. It is significant to increase the fibre link’s length of the FP-DRoF access network using common infrastructure. In addition, the simulation results are demonstrated that the FP-DRoF with non-uniform Wavelength Division Multiplexing (WDM) is more robust against four wave mixing impairment than the conventional WDM technique with uniform wavelength allocation and has better performance in terms of BER. It is clearly verified that the lunched power penalty at CS for DRoF link with uniform WDM techniques is about 2 dB higher than non-uniform WDM technique. Furthermore, uniform WDM method requires more bandwidth than non-uniform scheme which depends on the total number of channels and channels spacing

Physical layer aware open optical networking

L'abstract è presente nell'allegato / the abstract is in the attachmen

An Optical Grooming Switch for High-Speed Traffic Aggregation in Time, Space and Wavelength

In this book a novel optical switch is designed, developed, and tested. The switch integrates optical switching, transparent traffic aggregation/grooming, and optical regener-ation. Innovative switch subsystems are developed that enable these functionalities, including all-optical OTDM-to-WDM converters. High capacity ring interconnection between metro-core rings, carrying 130 Gbit/s OTDM traffic, and metro-access rings carring 43 Gbit/s WDM traffic is experimentally demonstrated. The developed switch features flexibility in bandwidth provisioning, scalability to higher traffic volumes, and backward compatibility with existing network implementations in a future-proof way