High Speed Railway Wireless Communications: Efficiency v.s. Fairness

High speed railways (HSRs) have been deployed widely all over the world in recent years. Different from traditional cellular communication, its high mobility makes it essential to implement power allocation along the time. In the HSR case, the transmission rate depends greatly on the distance between the base station (BS) and the train. As a result, the train receives a time varying data rate service when passing by a BS. It is clear that the most efficient power allocation will spend all the power when the train is nearest from the BS, which will cause great unfairness along the time. On the other hand, the channel inversion allocation achieves the best fairness in terms of constant rate transmission. However, its power efficiency is much lower. Therefore, the power efficiency and the fairness along time are two incompatible objects. For the HSR cellular system considered in this paper, a trade-off between the two is achieved by proposing a temporal proportional fair power allocation scheme. Besides, near optimal closed form solution and one algorithm finding the $\epsilon$-optimal allocation are presented.Comment: 16 pages, 6 figure

The philosophy and practice of Taktfahrplan: a case-study of the East Coast Main Line.

Executive Summary This Working Paper has three purposes, represented by three Parts: - to explain the principles of the Taktfahrplan approach to railway timetabling; - to summarise the implications of the background research on the structure of the network; and - to describe the exercise of constructing a Taktfahrplan for the East Coast Main Line that formed the case-study of the potential benefits of such a scheme compared with the existing timetable. In Part I the broad principles and objectives are first outlined, and the advantages and disadvantages discussed [§ 1.1,1.2]. A Taktfahrplan is based on standard hours and the careful, network-wide coordination of sewices. It is recognised that ultimately the choice between this and conventional timetabling methods must depend on an evaluation of the loss of present flexibility to adjust to time-specific market demands against the gains from enhanced connectivity and from the fact of regularity. Issues concerning resources and the management of peak periods are also explained. Terminology is then dealt with because words and phrases are being used with imprecise and various meanings [§1.3]. There follows a detailed account of the arithmetic rules through which the ideal relationships between train (and bus) sewices can be attained, together with an explanation of the measures that can be taken to make the best compromises in the face of the characteristics of the real network - or to adjust it over time [§ 1.4]. In Part 2 the research to highlight features of the underlying demand for travel is described. This is not a necessary component of strategic timetable planning, but it is argued that it is desirable in order both to break free from the historical baggage and to seize the business, environmental and social-policy opportunities that a 'clean- sheet' timetable would present [§2.1]. The provisional findings from this work (it was left incomplete for reasons that are explained) are then deployed to form the skeleton of a national network connecting 100 important centres with 158 links. This is followed by an analysis of the very variable standards of the rail timetable on those links and of the road competition and by an account of some first thoughts as to how a full-scale Taktfahrplan might start to be developed on this network [§2.2]. This emphasises the inter-relationships between sewices and the inescapable consequences for pathing trains, once it is accepted that sensible spacing of services and striving for good connectivity are more important than optimising routes on a self-contained basis. It was thought appropriate to include a summary of the findings regarding the low-density end of the current rail system in order to indicate the issues that Taktfahrplan might raise in this respect [§2.3]. The East Coast case-study is presented in Part 3. Some technical matters are explained first, including the key point that the exercise used the Viriato timetabling software employed by the Swiss Federal Railways (and many other systems) to construct Taktfahrpliine [§3.1]. Successive sub-parts then describe groups of services: long-distance [§3.2], services within Scotland [§3.3], services in North East England [§3.4], the trans-Pennine network [§3.5] and some of the Yorkshire services [§3.6]

Options for reshaping the railway

In many countries the mismatch between what the railways offer and what the customers want has caused significant economic inefficiency and severe financial strains for the railways and their government owners. The concept of the railway as a monolithic entity is so strong in many countries as to be a roadblock against reshaping the railway. The authors explore four options which can be used to reshape the railways. First is the lines of business option which improves accountability and responsiveness to markets. The second is the competitive access option which introduces intramodal competition in selected markets, while maintaining unitary control over most railway operations. The third is the"wholesaler"option which would accomplish an excellent marketing job, but the actual operation would remain in monolithic hands. Finally there is the"toll rail enterprise"option which comes closest to reflecting a theoretical model of marketing effectiveness, however it would generate potential operating conflicts and higher transaction costs. The authors show that one generalization holds true in all circumstances: a monolithic railway does not function well in a market economy in competition with privately owned, properly regulated competitors - especially trucking. The authors point out that solutions will vary, but the universal objective as an economy becomes more market driven is to make the railway more market sensitive.Railways Transport,Roads&Highways,Environmental Economics&Policies,Banks&Banking Reform,ICT Policy and Strategies

Different approaches and responsibilities for investment sustainability in EU railway infrastructure: Four case studies

This paper describes the approach to investment in rail infrastructure in four different European countries (Great Britain, France, Germany, and the Netherlands) with a view to understanding whether and how these countries differ in their approach to the sustainability of investment in infrastructure. We compare and contrast different approaches to investment, such as: The direct role of government; The role of the economic regulator, where available; The influence of particular ownership agreements, such as the use of concessions for high-speed lines; Any differential treatment of different assets, and any differential treatment of different items of expenditure, such as maintenance, renewals, and enhancements; The role played by private capital (in infrastructure as separate from passenger and freight train operations); and The existence of a (more or less unlimited), either direct or indirect, state guarantee on debt issued to fund investment in network assets. In analysing the European case studies, the paper asks the following questions, which may differ across infrastructure categories (for instance track/signalling, stations, and high-speed lines): (i) What is the ownership structure of each IM? (ii) Who “sponsors” and specifies investment? (iii) Who is responsible for planning and approving investment? (iv) What are the ultimate funding sources of investment? (v) Who is responsible for delivering investment? (vi) What is the role of the independent economic and technical regulator (where availble) vis-à-vis the government? (vii) Is there any (direct or indirect) market mechanism, for instance as part of incentive regulation, that is mimicked when incentivising the monopoly provider of infrastructure to achieve a sustainable level of investment? The paper concludes with some policy considerations and recommendations based on the four case studies examined.railway; reform; investment in public transport