On the dynamics of valley times and its application to bulk-transfer scheduling

Periods of low load have been used for the scheduling of non-interactive tasks since the early stages of computing. Nowadays, the scheduling of bulk transfers—i.e., large-volume transfers without precise timing, such as database distribution, resources replication or backups—stands out among such tasks, given its direct effect on both the performance and billing of networks. Through visual inspection of traffic-demand curves of diverse points of presence (PoP), either a network, link, Internet service provider or Internet exchange point, it becomes apparent that low-use periods of bandwidth demands occur at early morning, showing a noticeable convex shape. Such observation led us to study and model the time when such demands reach their minimum, on what we have named valley time of a PoP, as an approximation to the ideal moment to carry out bulk transfers. After studying and modeling single-PoP scenarios both temporally and spatially seeking homogeneity in the phenomenon, as well as its extension to multi-PoP scenarios or paths—a meta-PoP constructed as the aggregation of several single PoPs—, we propose a final predictor system for the valley time. This tool works as an oracle for scheduling bulk transfers, with different versions according to time scales and the desired trade-off between precision and complexity. The evaluation of the system, named VTP, has proven its usefulness with errors below an hour on estimating the occurrence of valley times, as well as errors around 10% in terms of bandwidth between the prediction and actual valley trafficThis work has been partially supported by the European Commission under the project H2020 METRO-HAUL (Project ID: 761727

Product-Related Risk and Cognitive Biases: The Shortcomings of Enterprise Liability

Products liability law has witnessed a long debate over whether manufacturers should be held strictly liable for the injuries that products cause. Recently, some have argued that psychological research on human judgment supports adopting a regime of strict enterprise liability for injuries caused by product design. These new proponents of enterprise liability argue that the current system, in which manufacturer liability for product design turns on the manufacturer\u27s negligence, allows manufacturers to induce consumers into undertaking inefficiently dangerous levels or types of consumption. In this paper we argue that the new proponents of enterprise liability have: (1) not provided any more than anecdotal evidence for their thesis; (2) failed to account for the mechanisms the law already has available to counter manufacturer manipulation of consumers; and (3) made no effort to address the well-known problems enterprise liability creates. Furthermore, even on its own terms, the new arguments for enterprise liability fail to consider the tendency of some manufacturers to exacerbate the risks that some products pose - a tendency that enterprise liability would exacerbate. In short, the insights gleaned from psychological research on human judgment do not support adopting a system of strict enterprise liability for products

Evaluation of data centre networks and future directions

Traffic forecasts predict a more than threefold increase in the global datacentre workload in coming years, caused by the increasing adoption of cloud and data-intensive applications. Consequently, there has been an unprecedented need for ultra-high throughput and minimal latency. Currently deployed hierarchical architectures using electronic packet switching technologies are costly and energy-inefficient. Very high capacity switches are required to satisfy the enormous bandwidth requirements of cloud datacentres and this limits the overall network scalability. With the maturity of photonic components, turning to optical switching in data centres is a viable option to accommodate greater bandwidth and network flexibility while potentially minimising the latency, cost and power consumption. Various DCN architectures have been proposed to date and this thesis includes a comparative analysis of such electronic and optical topologies to judge their suitability based on network performance parameters and cost/energy effectiveness, while identifying the challenges faced by recent DCN infrastructures. An analytical Layer 2 switching model is introduced that can alleviate the simulation scalability problem and evaluate the performance of the underlying DCN architecture. This model is also used to judge the variation in traffic arrival/offloading at the intermediate queueing stages and the findings are used to derive closed form expressions for traffic arrival rates and delay. The results from the simulated network demonstrate the impact of buffering and versubscription and reveal the potential bottlenecks and network design tradeoffs. TCP traffic forms the bulk of current DCN workload and so the designed network is further modified to include TCP flows generated from a realistic traffic generator for assessing the impact of Layer 4 congestion control on the DCN performance with standard TCP and datacentre specific TCP protocols (DCTCP). Optical DCN architectures mostly concentrate on core-tier switching. However, substantial energy saving is possible by introducing optics in the edge tiers. Hence, a new approach to optical switching is introduced using Optical ToR switches which can offer better delay performance than commodity switches of similiar size, while having far less power dissipation. An all-optical topology has been further outlined for the efficient implementation of the optical switch meeting the future scalability demands

Modelling and analysis of Internet pricing and revenue distribution.

Cheung, Yang.Thesis (M.Phil.)--Chinese University of Hong Kong, 2008.Includes bibliographical references (leaves 85-89).Abstracts in English and Chinese.Abstract --- p.iAcknowledgement --- p.ivChapter 1 --- Introduction --- p.1Chapter 2 --- Related Works --- p.4Chapter 2.1 --- Pricing Mechanisms --- p.4Chapter 2.1.1 --- Current Situation --- p.4Chapter 2.1.2 --- Proposed Pricing Mechanisms --- p.6Chapter 2.1.3 --- Congestion Pricing --- p.9Chapter 2.1.4 --- Bandwidth Allocation Mechanism --- p.10Chapter 2.2 --- Revenue Distribution Mechanisms --- p.12Chapter 2.2.1 --- Current Situation --- p.12Chapter 2.2.2 --- Novel Revenue Distribution Mechanisms --- p.13Chapter 3 --- Problems in Revenue Collecting Stage --- p.16Chapter 3.1 --- Introduction --- p.17Chapter 3.1.1 --- Desirable Characteristics of Internet Pricing Mechanism --- p.19Chapter 3.1.2 --- Existing Solution --- p.21Chapter 3.1.3 --- Applying Insurance into Internet Pricing --- p.22Chapter 3.2 --- The Internet Pricing Model --- p.25Chapter 3.2.1 --- System Model --- p.25Chapter 3.2.2 --- Decisions Time Scales --- p.27Chapter 3.2.3 --- Micro Time Scale Pricing --- p.28Chapter 3.2.4 --- Macro Time Scale Pricing --- p.29Chapter 3.3 --- Actuarially Fair Coinsurance Function --- p.30Chapter 3.3.1 --- The Actuarially Fair Coinsurance Function --- p.32Chapter 3.3.2 --- Properties of the Actuarially Fair Coinsurance Function --- p.34Chapter 3.3.3 --- How Much Insurance Should a User Buy? --- p.35Chapter 3.3.4 --- Numerical Examples --- p.37Chapter 3.4 --- Premium Coinsurance Function --- p.40Chapter 3.4.1 --- Problems of Allowing Pull Insurance --- p.41Chapter 3.4.2 --- The Premium Coinsurance Function --- p.43Chapter 3.4.3 --- Properties of the premium coinsurance function --- p.44Chapter 3.4.4 --- Numerical Example --- p.46Chapter 4 --- Problems in Revenue Distributing Stage --- p.48Chapter 4.1 --- Introduction --- p.50Chapter 4.2 --- System Models --- p.52Chapter 4.2.1 --- Topology Model --- p.52Chapter 4.2.2 --- Traffic Model --- p.54Chapter 4.3 --- Settlement Model and Definition of Fair Price --- p.55Chapter 4.3.1 --- Bilateral Settlement --- p.55Chapter 4.3.2 --- Shapley Settlement --- p.58Chapter 4.4 --- Fair Price Achieving the Shapley Value: The Symmetric Case --- p.61Chapter 4.5 --- Properties of the Fair Prices in the Symmetric Case --- p.65Chapter 4.5.1 --- Sensitivity to traffic pattern α --- p.65Chapter 4.5.2 --- Sensitivity to network topology parame- ters p and d --- p.67Chapter 4.6 --- Fair Price Achieving the Shapley Value: The Asym- metric Case --- p.70Chapter 4.7 --- Distributed and Local Approximation of the Fair Price --- p.71Chapter 5 --- Conclusions --- p.74Chapter A --- Mathematical Proofs --- p.77Chapter A.l --- Mathematical Proof for Chapter 3 --- p.77Chapter A.1.1 --- Proof of Theorem 3.3.2 --- p.77Chapter A.1.2 --- Proof of Proposition 3.3.5 --- p.77Chapter A.1.3 --- Proof of Proposition 3.3.6 --- p.78Chapter A.1.4 --- Proof of Proposition 3.3.7 --- p.78Chapter A.1.5 --- Proof of Proposition 3.4.1 --- p.79Chapter A.1.6 --- Proof of Proposition 3.4.3 --- p.79Chapter A.1.7 --- Proof of Proposition 3.4.5 --- p.80Chapter A.2 --- Mathematical Proof for Chapter 4 --- p.81Chapter A.2.1 --- Proof of Theorem 4.4.2 --- p.81Chapter A.2.2 --- Proof of Theorem (4.6.1) --- p.83Chapter A.2.3 --- Terms Description of Equation (4.1) --- p.84Bibliography --- p.8

5GAuRA. D3.3: RAN Analytics Mechanisms and Performance Benchmarking of Video, Time Critical, and Social Applications

5GAuRA deliverable D3.3.This is the final deliverable of Work Package 3 (WP3) of the 5GAuRA project, providing a report on the project’s developments on the topics of Radio Access Network (RAN) analytics and application performance benchmarking. The focus of this deliverable is to extend and deepen the methods and results provided in the 5GAuRA deliverable D3.2 in the context of specific use scenarios of video, time critical, and social applications. In this respect, four major topics of WP3 of 5GAuRA – namely edge-cloud enhanced RAN architecture, machine learning assisted Random Access Channel (RACH) approach, Multi-access Edge Computing (MEC) content caching, and active queue management – are put forward. Specifically, this document provides a detailed discussion on the service level agreement between tenant and service provider in the context of network slicing in Fifth Generation (5G) communication networks. Network slicing is considered as a key enabler to 5G communication system. Legacy telecommunication networks have been providing various services to all kinds of customers through a single network infrastructure. In contrast, by deploying network slicing, operators are now able to partition one network into individual slices, each with its own configuration and Quality of Service (QoS) requirements. There are many applications across industry that open new business opportunities with new business models. Every application instance requires an independent slice with its own network functions and features, whereby every single slice needs an individual Service Level Agreement (SLA). In D3.3, we propose a comprehensive end-to-end structure of SLA between the tenant and the service provider of sliced 5G network, which balances the interests of both sides. The proposed SLA defines reliability, availability, and performance of delivered telecommunication services in order to ensure that right information is delivered to the right destination at right time, safely and securely. We also discuss the metrics of slicebased network SLA such as throughput, penalty, cost, revenue, profit, and QoS related metrics, which are, in the view of 5GAuRA, critical features of the agreement.Peer ReviewedPostprint (published version

The institutional aspects of competitive access in the Western Canadian rail system

Rail rates and system costs are important to the profitability of Western Canadian agriculture. This importance is due to the high cost of transporting grain to export position combined with rail’s cost advantage in relation to other modes of bulk transportation. World grain markets are competitive and any increase in freight rate caused by inefficiency or market power can not be passed on consumers. This thesis introduces and discusses a way to create competition in the rail industry through vertical separation of rolling stock and track. The discussion is motivated by a transactions cost framework, whereby key features of a vertically integrated railway such as we have in Canada are contrasted with those of a vertically separated railway, as is the case today in Sweden. The two systems share common characteristics, but the way system participants interact are ultimately very different. Canada’s vertically integrated railway system creates strong incentives for infrastructure investment along with maintenance and congestion management, but a vertically integrated system discourages new competition in the industry. Conversely, the vertically separated Swedish system creates strong incentives for inter-rail competition and improvements in customer service. Canada’s rail system is now less subsidized than ever, while the Swedish system still requires significant public outlay, and will need continued government support. Due to its cost structure, the choice of regulation in the rail sector continues to be a trade-off between railway cost recovery and fair rates for shippers. As applied to Canada, the example of Sweden illustrates that a limited access regime in rail can operationally function and reduce market power concerns. An access regime can achieve this reduction by supporting contestable pricing that will limit the ability of railways to price discriminate

An Investigation to Evaluate the Feasibility of an Intermodal Freight Transport System.

The threat of greenhouse gases and the resulting climate change have been causing concern at international levels. This has led towards new sustainable policies towards reducing the anthropogenic effects on the environment and the population through promoting sustainable solutions for the freight industry. The research was prompted by the growing concerns that were no mode-choice tool to select as an alternative to road freight transport. There were growing concerns that a large percentage of transport related negativities, related various costs and pollution costs, losses arising from traffic accidents, delay costs from congestion and abatement costs due to climate impacts of transport, etc., were not being borne by the user. Economists have defined them as external costs. Internalising these external costs has been regarded as an efficient way to share the transport related costs. The aim of this research was to construct a freight mode choice model, based on total transport costs, as a mode choice substitution tool. This model would allow the feasibility of choosing alternative intermodal system to a primarily ‘road system’. The thesis postulates a novel model in computing total freight transport costs incurred during the total transit of goods along three North European transport corridors. The model evaluated the total costs summing the internal, external and time costs for varied mode choices from unimodal and the second level of intermodal transport systems. The research outcomes have shown the influences of total costs on the shipper and the preferred mode choices from the available mode/route options with sustainable transport solutions. The impacts of such alternatives were evaluated in this research. This will allow the embedding of intermodal infrastructures as sustainable and alternative mode choices for the freight industry