A systematic analysis of equivalence in multistage networks

Many approaches to switching in optoelectronic and optical networks decompose the switching function across multiple stages or hops. This paper addresses the problem of determining whether two multistage or multihop networks are functionally equivalent. Various ad-hoc methods have been used in the past to establish such equivalences. A systematic method for determining equivalence is presented based on properties of the link permutations used to interconnect stages of the network. This method is useful in laying out multistage networks, in determining optimal channel assignments for multihop networks, and in establishing the routing required in such networks. A purely graphical variant of the method, requiring no mathematics or calculations, is also described

Analysis of searching mechanisms in hierarchical p2p based overlay networks

Proceedings of: The 6th Annual Mediterranean Ad Hoc Networking Workshop (Med Hoc Net 2007. (Corfu, Greece), June 2007This work presents a study of searching mechanisms in Peer-to-Peer (p2p) networks. The aim of this research line is to analyse cross-searching mechanisms that will allow the hierarchical interconnection of p2p networks. A set of relevant metrics for interconnection scenarios are defined to evaluate scalability, robustness and routing latency.This work has been partially supported by the European Union under the IST Content (FP6-2006-IST-507295) project and by the Madrid regional government under the Biogridnet (CAM, S-0505/TIC-0101) project.Publicad

Towards a Novel Cooperative Logistics Information System Framework

Supply Chains and Logistics have a growing importance in global economy. Supply Chain Information Systems over the world are heterogeneous and each one can both produce and receive massive amounts of structured and unstructured data in real-time, which are usually generated by information systems, connected objects or manually by humans. This heterogeneity is due to Logistics Information Systems components and processes that are developed by different modelling methods and running on many platforms; hence, decision making process is difficult in such multi-actor environment. In this paper we identify some current challenges and integration issues between separately designed Logistics Information Systems (LIS), and we propose a Distributed Cooperative Logistics Platform (DCLP) framework based on NoSQL, which facilitates real-time cooperation between stakeholders and improves decision making process in a multi-actor environment. We included also a case study of Hospital Supply Chain (HSC), and a brief discussion on perspectives and future scope of work

Stencils and problem partitionings: Their influence on the performance of multiple processor systems

Given a discretization stencil, partitioning the problem domain is an important first step for the efficient solution of partial differential equations on multiple processor systems. Partitions are derived that minimize interprocessor communication when the number of processors is known a priori and each domain partition is assigned to a different processor. This partitioning technique uses the stencil structure to select appropriate partition shapes. For square problem domains, it is shown that non-standard partitions (e.g., hexagons) are frequently preferable to the standard square partitions for a variety of commonly used stencils. This investigation is concluded with a formalization of the relationship between partition shape, stencil structure, and architecture, allowing selection of optimal partitions for a variety of parallel systems

Regulatory Uncertainty and Inefficiency for the Development of Merchant Lines in Europe

This paper evaluates regulatory uncertainty and inefficiency that may prevent merchant transmission investors from committing in Europe, in particular when they are dominant generators. We argue that market players may perceive regulatory uncertainty to acquire exemption on merchant line mainly because of the discretion given for the application of Art. 7 of the Regulation 1228/2003 on cross-border exchanges. However we show that an emerging strategy of the European Commission for granting exemption on merchant transmission line can be eventually derived from recent legal and regulatory proceedings. It mainly consists in relying on TSOs to build merchant lines. We demonstrate that this strategy is neither a first best nor a second best given imperfect unbundling and the current flows in the allocation of regulatory powers. Indeed, it prevents merchant line investment by dominant generators with low generation cost while they have currently more incentive than TSOs to build merchant lines. Since unregulated merchant transmission investment by generators would be problematic, we show eventually that the current strategy of the application of Regulation can easily be fine-tuned to reach this second-best optimum.Regulatory Uncertainty and Inefficiency for the Development of Merchant Lines in Europe

Exporting Telecommunications Regulation: The U.S.-Japan Negotiations on Interconnection Pricing

Since 1997, the U.S. government has attempted to use the World Trade Organization (WTO) agreement on telecommunications services as a vehicle for 'exporting' American principles of telecommunications regulation to other nations. The United States took the position in 1997 that the WTO telecommunications agreement requires its signatory nations to follow the practices of the Federal Communications Commission (FCC) on telecommunications regulatory policy. Subsequently, the Office of the U.S. Trade Representative (USTR) has sought to influence, under the implicit threat of trade sanctions, Japan's domestic regulatory policy on the pricing of mandatory competitor access to the unbundled elements of the local network belonging to the operating companies of Nippon Telegraph and Telephone Corporation (NTT). In this Article, we examine the substantive difficulties of engrafting the FCC's interconnection policy onto the telecommunications marketplace of another nation. For more than five years, many American experts on telecommunications policy have disagreed whether American consumers have benefited from the very FCC policies that the USTR would have Japanese regulators emulate. The USTR's initiative appears to ignore that the transition to costoriented rates for interconnection and retail telecommunications services has been a difficult and unfinished process in the United States; that the cost models used by the FCC to set interconnection prices have significant deficiencies; that actual interconnection prices both within and outside the United States diverge considerably from the estimates of the FCC's cost models; that variations across countries in the prices of inputs have a significant effect on the costs of interconnection; and that, with respect to depreciation in particular, regulators treat this cost differently'and, from an economic perspective, more reasonably'in Japan than in the United States. Such substantive economic considerations suggest why the FCC's policy in this area has generated continuous litigation, including two Supreme Court cases, since 1996 and consequently is too unresolved at this point in the American experience for the United States to force on its trading partners. Next, we ask whether the USTR has the detailed knowledge required to negotiate trade agreements on interconnection pricing. We question the propriety of using the USTR to influence the domestic regulatory policy of another country on a topic as complex as the efficient pricing of mandatory access to unbundled network elements. The USTR's power to formulate trade policy on this subject resides in officials who are unlikely to possess the economic expertise and resources necessary to evaluate the consumer-welfare implications of the policies that they would have Japan and other nations adopt. For these reasons, the USTR cannot credibly make the interconnection pricing policies of another nation a legitimate concern of U.S. trade policy.

When good intentions are not enough: sequential entry and competition in the Turkish mobile industry

A decade into the liberalization of the Turkish mobile industry, the sector remains one of the most concentrated in Europe. In this paper we analyze the links between the regulatory environment and competitive outcomes in the Turkish context. We argue that seven years of duopoly incumbency resulted in a significant first-mover advantage. We then focus on the role of the regulatory tools that could potentially restrain the incumbent operators’ first-mover advantage and stimulate competition: national roaming, interconnection regulation, and number portability

Crosstalk-free Conjugate Networks for Optical Multicast Switching

High-speed photonic switching networks can switch optical signals at the rate of several terabits per second. However, they suffer from an intrinsic crosstalk problem when two optical signals cross at the same switch element. To avoid crosstalk, active connections must be node-disjoint in the switching network. In this paper, we propose a sequence of decomposition and merge operations, called conjugate transformation, performed on each switch element to tackle this problem. The network resulting from this transformation is called conjugate network. By using the numbering-schemes of networks, we prove that if the route assignments in the original network are link-disjoint, their corresponding ones in the conjugate network would be node-disjoint. Thus, traditional nonblocking switching networks can be transformed into crosstalk-free optical switches in a routine manner. Furthermore, we show that crosstalk-free multicast switches can also be obtained from existing nonblocking multicast switches via the same conjugate transformation.Comment: 10 page