A passivity-based stability criterion for a class of interconnected systems and applications to biochemical reaction networks

This paper presents a stability test for a class of interconnected nonlinear systems motivated by biochemical reaction networks. One of the main results determines global asymptotic stability of the network from the diagonal stability of a "dissipativity matrix" which incorporates information about the passivity properties of the subsystems, the interconnection structure of the network, and the signs of the interconnection terms. This stability test encompasses the "secant criterion" for cyclic networks presented in our previous paper, and extends it to a general interconnection structure represented by a graph. A second main result allows one to accommodate state products. This extension makes the new stability criterion applicable to a broader class of models, even in the case of cyclic systems. The new stability test is illustrated on a mitogen activated protein kinase (MAPK) cascade model, and on a branched interconnection structure motivated by metabolic networks. Finally, another result addresses the robustness of stability in the presence of diffusion terms in a compartmental system made out of identical systems.Comment: See http://www.math.rutgers.edu/~sontag/PUBDIR/index.html for related (p)reprint

Is America Exporting Misguided Telecommunications Policy? The U.S.-Japan Telecom Trade Negotiations and Beyond

Global telecommunications markets have traditionally been closed to foreign trade and investment. Recent World Trade Organization negotiations resulted in a Basic Telecommunications agreement that sought to construct a multilateral framework to reverse that trend and begin opening telecom markets worldwide. Regrettably, this new WTO framework is quite ambiguous and open to pro-regulatory interpretations by member states. In fact, during recent bilateral trade negotiations with Japan, U.S. government officials adopted the position that the new framework allowed them to demand that the Japanese government adopt very specific regulatory provisions regarding telecom network interconnection and pricing policies. The Office of the U.S. Trade Representative argued that Japanese officials should require their domestic telecom providers to share their networks with rivals at a generously discounted price to encourage greater resale competition. Those interconnection and line-sharing rules were borrowed directly from the U.S. Telecommunications Act of 1996, a piece of legislation that remains the subject of intense debate within the United States. Good evidence now exists that those rules generally retard net-work investment and innovation by encouraging infrastructure sharing over facilities-based investment. Consequently, the USTR has generated resentment on the part of Japan and other trading partners as it has attempted to force them to adopt heavy-handed telecommunications mandates that have very little to do with legitimate free-trade policy. The USTR must discontinue efforts to impose American telecommunications regulations on other countries as part of free-trade negotiations and should instead focus on reforming or eliminating the most serious barriers to foreign direct investment both here and abroad

Telecommunications reform in Uganda

The paper documents the case of Uganda's telecommunications reform. Uganda is one of only two countries in Africa that decided to privatize telecommunications in a competitive framework by selling a second national operator license. The authors find that Uganda did not sacrifice significant sales proceeds by choosing competition, but instead gained tremendously in both the speed and scale of investment from its early focus on competition.Knowledge Economy,ICT Policy and Strategies,Environmental Economics&Policies,Economic Theory&Research,Decentralization,ICT Policy and Strategies,Economic Theory&Research,Environmental Economics&Policies,Public Sector Economics&Finance,Education for the Knowledge Economy

Telecommunications reform in Malawi

In 1998 the Government of Malawi decided to reform its telecommunications sector. Although the reform was ambitious in some ways, it was modest when compared with the most ambitious reforms adopted elsewhere in Sub-Saharan Africa. The two main accomplishments were splitting the incumbent fixed line monopoly, the Malawi Post and Telecommunications Corporation, into two companies-Malawi Telecommunications Limited (MTL) and Malawi Post Corporation (MPC)-and issuing two new cellular licenses to two new private entrants. In addition, the Government also established a new regulator which was separate from, but heavily dependent on, the Ministry of Information and liberalized entry in value-added and Internet services. However, the Government had neither privatized the fixed-line telecommunications operator nor introduced competition in fixed-line services by the end of 2002. Clarke, Gebreab, and Mgombelo discuss sector performance before reform, details of the reform, the political motivation for reform, and events in the five years following the reform. The reform yielded mixed results. Although cellular penetration and Internet use expanded dramatically following reform, prices increased, especially for cellular calls, and fixed-line penetration remains low by regional standards.Public Sector Economics&Finance,Rural Communications,Telecommunications Infrastructure,ICT Policy and Strategies,Knowledge Economy,ICT Policy and Strategies,Rural Communications,Education for the Knowledge Economy,Knowledge Economy,Public Sector Economics&Finance

Competition in Industries Recently Deregulated in Japan

Deregulation in Japan has been caused by both external and internal factors. External factors include requests by the United States and the European Community, where deregulation measures were extensively implemented in order to facilitate these countries\u27 enterprises access into Japan\u27s market. Internal factors include the necessity for the privatization of state or public corporations in order to utilize private initiative to its fullest extent and for the reduction of differences between domestic and international prices

On Modeling Heterogeneous Wireless Networks Using Non-Poisson Point Processes

Future wireless networks are required to support 1000 times higher data rate, than the current LTE standard. In order to meet the ever increasing demand, it is inevitable that, future wireless networks will have to develop seamless interconnection between multiple technologies. A manifestation of this idea is the collaboration among different types of network tiers such as macro and small cells, leading to the so-called heterogeneous networks (HetNets). Researchers have used stochastic geometry to analyze such networks and understand their real potential. Unsurprisingly, it has been revealed that interference has a detrimental effect on performance, especially if not modeled properly. Interference can be correlated in space and/or time, which has been overlooked in the past. For instance, it is normally assumed that the nodes are located completely independent of each other and follow a homogeneous Poisson point process (PPP), which is not necessarily true in real networks since the node locations are spatially dependent. In addition, the interference correlation created by correlated stochastic processes has mostly been ignored. To this end, we take a different approach in modeling the interference where we use non-PPP, as well as we study the impact of spatial and temporal correlation on the performance of HetNets. To illustrate the impact of correlation on performance, we consider three case studies from real-life scenarios. Specifically, we use massive multiple-input multiple-output (MIMO) to understand the impact of spatial correlation; we use the random medium access protocol to examine the temporal correlation; and we use cooperative relay networks to illustrate the spatial-temporal correlation. We present several numerical examples through which we demonstrate the impact of various correlation types on the performance of HetNets.Comment: Submitted to IEEE Communications Magazin