Performance modeling of QoS differentiation in optical packet switching via FDL access limitation

We present an exact analytical model for single-wavelength quality of service (QoS) differentiation in a two-class optical packet switch. In this system, QoS differentiation is achieved by limiting the set of fiber delay lines (FDLs) to the low-priority class, whereas the high-priority class is allowed to access the entire FDL bank. The analytical model is based on multi-regime Markov fluid queues and is extensible to multi-class systems with more than two classes. Markovian arrival process packet arrivals and phase-type distributed packet sizes are considered for the purpose of generality. The proposed analytical model is validated through simulations. The numerical results provide insight into determining appropriate subsets of FDLs allowed for the access of the low-priority class. The results also show that it is possible to direct almost all the packet losses to the low-priority class under moderate loads. © 2017, Springer Science+Business Media New York

Cross-layer modeling and optimization of next-generation internet networks

Scaling traditional telecommunication networks so that they are able to cope with the volume of future traffic demands and the stringent European Commission (EC) regulations on emissions would entail unaffordable investments. For this very reason, the design of an innovative ultra-high bandwidth power-efficient network architecture is nowadays a bold topic within the research community. So far, the independent evolution of network layers has resulted in isolated, and hence, far-from-optimal contributions, which have eventually led to the issues today's networks are facing such as inefficient energy strategy, limited network scalability and flexibility, reduced network manageability and increased overall network and customer services costs. Consequently, there is currently large consensus among network operators and the research community that cross-layer interaction and coordination is fundamental for the proper architectural design of next-generation Internet networks. This thesis actively contributes to the this goal by addressing the modeling, optimization and performance analysis of a set of potential technologies to be deployed in future cross-layer network architectures. By applying a transversal design approach (i.e., joint consideration of several network layers), we aim for achieving the maximization of the integration of the different network layers involved in each specific problem. To this end, Part I provides a comprehensive evaluation of optical transport networks (OTNs) based on layer 2 (L2) sub-wavelength switching (SWS) technologies, also taking into consideration the impact of physical layer impairments (PLIs) (L0 phenomena). Indeed, the recent and relevant advances in optical technologies have dramatically increased the impact that PLIs have on the optical signal quality, particularly in the context of SWS networks. Then, in Part II of the thesis, we present a set of case studies where it is shown that the application of operations research (OR) methodologies in the desing/planning stage of future cross-layer Internet network architectures leads to the successful joint optimization of key network performance indicators (KPIs) such as cost (i.e., CAPEX/OPEX), resources usage and energy consumption. OR can definitely play an important role by allowing network designers/architects to obtain good near-optimal solutions to real-sized problems within practical running times

The productivity spillovers of foreign direct investment in China: a computable general equilibrium model

One of the most important aspects of foreign direct investment (FDI) is that it embodies advanced technologies and business practices which can spill over to domestic firms via various channels, e.g. labour mobility, input-output linkages, export of multinational affiliates, demonstration and competition. This research combines computable general equilibrium (CGE) modelling and econometric techniques to quantify FDI productivity spillovers. The research is conducted in the context of the Chinese economy. A static lOl-sector CGE model is constructed to measure the endogenous productivity spillovers of FDI. Spillover effects are analysed under three different market structure assumptions, namely perfect competition, monopolistic competition with homogeneous firms, and monopolistic competition with heterogeneous firms. The research results show that the presence of FDI productivity spillovers can generally improve the productivity and output level of domestic enterprises in China. Spillovers make foreign firms' total output decrease. But collectively, spillovers exert positive impact on national aggregate variables, i.e. GDP, total output and welfare. The market structure assumptions of monopolistic competition and firm heterogeneity provide more perspectives (e.g. product variety and scale) for this research than the assumption of perfect competition does. A removal of preferential corporate income tax treatment on foreign enterprises can increase the output level of domestic enterprises and promote national welfare. From a dynamic perspective, it could also promote the productivity splllovers from foreign firms

Factors affecting the development of sophisticated database marketing systems.

In the late 1980s, companies in a wide variety of industries began to implement segmented marketing strategies using database marketing (DBM) systems. Several surveys noted that some organisations were developing sophisticated DBM systems to achieve competitive advantage, while others, in similar marketplaces, seemed unable, or unwilling, to exploit the potential benefits of these powerful systems. Alternatively, evidence from industrial reports suggested that most companies were failing to fully exploit the capabilities oftheir systems. Hence, this research was designed to determine the factors affecting levels of sophistication in database marketing (DBM) systems. First, theories from marketing and information systems were synthesised to develop a generic model of DBM systems. Next, notions about the sources of competitive advantage were reviewed to identify potential factors promoting the development of sophisticated DBM systems. This review resulted in four such factors being hypothesised: market orientation as a specific organisation culture, database size (i.e. number of customers) as a key resource, locus of control of the senior marketing manager as an important individual characteristic, and the difference between consumer and business markets as a factor in firms' external environment. Empirical data were collected from two random samples of senior marketing managers in US catalogue companies using postal surveys. Data from the first sample (36 observations) were used to develop a valid and reliable construct to measure the level of sophistication in DBM systems. Further data were collected from a second random sample using two further postal surveys (69 observations), which confirmed and replicated the results obtained from the first sample. Overall, the research findings show that the development of sophisticated DBM systems is positively associated with two factors: market orientation of organisation culture, and database size. The other two factors - locus of control and type of market - failed to show any association with the level of sophistication in DBM systems. Further data analyses revealed a strong association between the elements of sophisticated OBM systems and marketing notions of sources of competitive advantage