Investigation of different techniques to upgrade legacy WDM communication systems

This thesis presents experimental investigation of different effects/techniques that can be used to upgrade legacy WDM communication systems. The main issue in upgrading legacy systems is that the fundamental setup, including components settings such as EDFA gains, does not need to be altered thus the improvement must be carried out at the network terminal. A general introduction to optical fibre communications is given at the beginning, including optical communication components and system impairments. Experimental techniques for performing laboratory optical transmission experiments are presented before the experimental work of this thesis. These techniques include optical transmitter and receiver designs as well as the design and operation of the recirculating loop. The main experimental work includes three different studies. The first study involves a development of line monitoring equipment that can be reliably used to monitor the performance of optically amplified long-haul undersea systems. This equipment can provide instant finding of the fault locations along the legacy communication link which in tum enables rapid repair execution to be performed hence upgrading the legacy system. The second study investigates the effect of changing the number of transmitted 1s and Os on the performance of WDM system. This effect can, in reality, be seen in some coding systems, e.g. forward-error correction (FEC) technique, where the proportion of the 1s and Os are changed at the transmitter by adding extra bits to the original bit sequence. The final study presents transmission results after all-optical format conversion from NRZ to CSRZ and from RZ to CSRZ using semiconductor optical amplifier in nonlinear optical loop mirror (SOA-NOLM). This study is mainly based on the fact that the use of all-optical processing, including format conversion, has become attractive for the future data networks that are proposed to be all-optical. The feasibility of the SOA-NOLM device for converting single and WDM signals is described. The optical conversion bandwidth and its limitations for WDM conversion are also investigated. All studies of this thesis employ 10Gbit/s single or WDM signals being transmitted over dispersion managed fibre span in the recirculating loop. The fibre span is composed of single-mode fibres (SMF) whose losses and dispersion are compensated using erbium-doped fibre amplifiers (EDFAs) and dispersion compensating fibres (DCFs), respectively. Different configurations of the fibre span are presented in different parts.

Cost-effective upgrade of WDM all-optical networks using overlay fibres and hop reduction links

Fibre overlay is a cost-effective technique to alleviate wavelength blocking in some links of a wavelength-routed optical network by increasing the number of wavelengths in those links. In this letter, we investigate the effects of overlaying fibre in an all-optical network (AON) based on GÉANT2 topology. The constraint-based routing and wavelength assignment (CB-RWA) algorithm locates where cost-efficient upgrades should be implemented. Through numerical examples, we demonstrate that the network capacity improves by 25 per cent by overlaying fibre on 10 per cent of the links, and by 12 per cent by providing hop reduction links comprising 2 per cent of the links. For the upgraded network, we also show the impact of dynamic traffic allocation on the blocking probability. Copyright © 2010 John Wiley & Sons, Ltd.

Cost-effective upgrade of WDM all-optical networks using overlay fibres and hop reduction links

Fibre overlay is a cost-effective technique to alleviate wavelength blocking in some links of a wavelength-routed optical network by increasing the number of wavelengths in those links. In this letter, we investigate the effects of overlaying fibre in an all-optical network (AON) based on GÉANT2 topology. The constraint-based routing and wavelength assignment (CB-RWA) algorithm locates where cost-efficient upgrades should be implemented. Through numerical examples, we demonstrate that the network capacity improves by 25 per cent by overlaying fibre on 10 per cent of the links, and by 12 per cent by providing hop reduction links comprising 2 per cent of the links. For the upgraded network, we also show the impact of dynamic traffic allocation on the blocking probability. Copyright © 2010 John Wiley & Sons, Ltd.

To what extent and in what manner do Chinese and Indian contract research organisation learn and upgrade with the unbundling the global pharmaceutical R&D value chain?

The paper applies the GVC framework to analyse the organisational and geographical reconfiguration of the global R&D function of leading US and European pharmaceutical MNCs. Though pharmaceutical MNCs have been outsourcing clinical trial activities since the mid-1990s, the outsourcing of discovery research tasks is a phenomenon of the 2000s (Ramirez 2013). Moreover, in the context of a crisis of R&D productivity and increasing pressure from shareholders, a number of US and European pharmaceutical MNCs are breaking up their R&D function in an attempt to increase flexibility and reduce risk as well as costs and are thereby restructuring the global architecture of their R&D function. This break-up, or unbundling (Sako 2006), of the R&D function is particularly interesting given the prevalence of market failure in innovation (Howells et al 2008), the non-modular nature of the R&D process in this industry (Pisano 2006) and the strategic important of this activity to the core competence and long-term competitive advantage of firms in this sector. The focus of this paper is on the outsourcing of R&D activities to Chinese and Indian independently-owned contract research organisations (CROs) and the way these firms are becoming integrated as service providers into the global R&D function (or R&D value chain) of pharmaceutical MNCs. Above all the paper is concerned with the development of capabilities of CROs from these two countries and the dynamics of upgrading in GVCs in knowledge-intensive functions. The paper therefore discusses the role of both knowledge flows within global pharmaceutical R&D value chains as well as national innovation systems on the development of capabilities of Chinese and Indian CROs. Our analysis is based on data from semi-structured interviews collected from senior R&D managers from a sample of ten US and European pharmaceutical MNCs and owners and senior R&D managers from five Chinese and five Indian CROs who are providing research services to MNCs in this industry. We discuss the emergence of R&D outsourcing in this industry and the nature and mechanisms of knowledge flows within R&D value chains. The embeddedness of CROS in the national innovation systems of their home countries is also discussed.