Cognitive radio systems specific for IMT systems: Operator’s view and perspectives

Cognitive radio (CR) is still an emerging and disruptive communication technology which is expected to improve the overall efficiency of the spectrum use. It is envisaged that cognitive radio systems (CRS) could impact many aspects of communications and in particular could facilitate accommodation of the increasing amount of services and applications in wireless networks. Intensive research on CR aims at maximising the utilisation of the limited radio spectrum resource. There have been many advances in CR regarding the technology development aspects; however supplementary research on regulation, policy and market structure reforms in relation with application specific deployment is still required before any CR-based spectrum access could be implemented for specific broadband mobile applications. Indeed, mobile community is still at an early stage of understanding and development of CR capabilities and it is premature to envisage wide deployment of CRS without careful consideration of regulatory and business issues. Therefore, this paper gives a classification of CR-based network and application scenarios, and investigates the feasibility of them from a regulatory perspective at a global level (ITU-R). Main part of this paper presents the wireless network operator’s approach to CRS specific for International Mobile Telecommunications (IMT) systems and proposes the radio environment map (REM) concept as a cognitive tool that increases environmental awareness in wireless network operator’s networks. Studies, which the authors performed internally and within the framework of a collaborative European project as well as within ITU-R yield the conclusion that, at shorter term, only intra-operator based CRS maximises the possibility for CR capabilities to be implemented.     

Investor valuations of Japan’s adoption of a territorial tax regime: quantifying the direct and competitive effects of international tax reform

This paper examines the impact of Japan’s 2009 adoption of a territorial tax regime using event study methods which leverage individual firm characteristics to identify underlying drivers of market reactions. Differences in Japanese firms’ foreign and domestic effective tax rates yield an aggregate capitalization effect of \(\yen \)4.3 trillion, while firms with less prior foreign exposure and fewer opportunities for tax avoidance experienced relatively larger abnormal returns. We attribute these results to tax savings on existing undistributed foreign earnings, enhanced opportunities for international expansion, and cultural biases against tax planning. Spillovers to the US (through tax or firm competition) appear insignificant.     

The Impact of Central Bank FX Interventions on Currency Components

This article assesses the impact of official FOREX interventionsof the three major central banks in terms of the dynamics ofthe currency components of the major exchange rates over theperiod 1989–2003. We identify the currency componentsof the mean and volatility processes of exchange rates usingthe framework developed recently by Bos and Shephard (2006).Our results show that, in general, concerted interventions tendto affect the dynamics of both currency components of the exchangerate. In contrast, unilateral interventions are found to primarilyaffect the currency of the central bank present in the market.Our findings also emphasize a role for interventions conductedby these central banks on other related FOREX markets.     

Combining an inter-sectoral carbon tax with sectoral mitigation policies: Impacts on the French forest sector

As France works out its plan to tackle climate change issues, questions are arising in the forest sector as to how sectoral mitigation programs such as those designed to enhance fuelwood consumption or to stimulate in-forest carbon sequestration may coincide with an inter-sectoral program such as an economy-wide carbon tax. This paper provides insights into this question by exploring the impacts of (1) a combination of a carbon tax and a fuelwood policy, and (2) a combination of a carbon tax and a sequestration policy on (i) the economy of the forest sector, and (ii) the dynamics of the forest resource. To do this, we used a modified version of the French Forest Sector Model (FFSM) and carried out simulations on a 2020 time horizon. Basing our analysis on the fuelwood sector, we showed that wood producers always benefit from the combination of a carbon tax with either a fuelwood policy or a sequestration policy at the national level. Conversely, and although it favors wood products instead of non-wood substitutes, a carbon tax always decreases consumer surpluses by increasing wood product prices. As a consequence, the combination of a carbon tax with sectoral policies is likely to raise questions about the political economy of the mitigation program. This is particularly true in the case of a combination of a carbon tax with a sequestration policy, which already decreases consumer surpluses. We eventually showed that by increasing transport costs between domestic regions, the carbon tax reallocates production patterns over French territory which could lead to the necessity of a regional breakdown of policy-mixes in the forest sector.     

Estimating Armington elasticities for sawnwood and application to the French Forest Sector Model

Domestic and foreign forest products consumptions are considered imperfectly substitutable in the French Forest Sector Model (FFSM). This assumption is justified by product heterogeneities that depend on production places, by the consumers habits or by the market structure. It leads us to implement the international trade in the FFSM via the Armington's theory of the demand for products distinguished by place of production. In this paper we propose a calibration of Armington's elasticities of substitution between French and foreign forest products. System-GMM estimators are applied to identify robust parameters using a panel data from France customs service.     

Estimation of a hedonic price equation for Burgundy wine

A hedonic price equation and two jury grade equations are estimated for Burgundy wine. The approach is the same as in an earlier Bordeaux wine paper (Combris et al., 1997). The data come from an experimental study that is very similar to the study on Bordeaux wines. The results for the two wine-growing regions are compared and discussed.     

Pricing CDOs with state-dependent stochastic recovery rates

Up to the 2007 crisis, research within bottom-up CDO models mainly concentrated on the dependence between defaults. Since then, due to substantial increases in market prices of systemic credit risk protection, more attention has been paid to recovery rate assumptions. In this paper, we use stochastic orders theory to assess the impact of recovery on CDOs and show that, in a factor copula framework, a decrease of recovery rates leads to an increase of the expected loss on senior tranches, even though the expected loss on the portfolio is kept fixed. This result applies to a wide range of latent factor models and is not specific to the Gaussian copula model. We then suggest introducing stochastic recovery rates in such a way that the conditional on the factor expected loss (or, equivalently, the large portfolio approximation) is the same as in the recovery markdown case. However, granular portfolios behave differently. We show that a markdown is associated with riskier portfolios than when using the stochastic recovery rate framework. As a consequence, the expected loss on a senior tranche is larger in the former case, whatever the attachment point. We also deal with implementation and numerical issues related to the pricing of CDOs within the stochastic recovery rate framework. Due to differences across names regarding the conditional (on the factor) losses given default, the standard recursion approach becomes problematic. We suggest approximating the conditional on the factor loss distributions, through expansions around some base distribution. Finally, we show that the independence and comonotonic cases provide some easy to compute bounds on expected losses of senior or equity tranches.