Universitat Pompeu Fabra

Displaying 1-32 of 32 results

  • White Papers // Jan 2012

    On the Limitations of Cooperation in Wireless Networks

    Cooperation in a large wireless network (such as a cellular system) is shown to have certain fundamental limitations: namely, even perfect cooperation cannot in general change an interference-limited network to a noise-limited one. In contrast to existing literature that routinely assumes that the spectral efficiency scales with log P as...

    Provided By Universitat Pompeu Fabra

  • White Papers // Jul 2011

    Accelerating Into The Abyss: Financial Dependence And The Great Depression

    The author's paper provides empirical support for the importance of financial distress in the propagation of the Great Depression. Even those in agreement are not unanimous in the mechanisms they propose. Friedman and Schwartz (1963) argue that bank failures caused money supply reductions which in turn depressed economic activity, while...

    Provided By Universitat Pompeu Fabra

  • White Papers // Apr 2011

    An Approximate Queueing Model for Multi-Rate Multi-User MIMO Systems

    A queueing model for multi-rate multi-user MIMO systems is presented. The model is built upon the assumption that the probability distribution of available destinations among the buffered frames at the Base Station (BS) is approximately the same as the probability distribution of the traffic arriving to the BS, this is,...

    Provided By Universitat Pompeu Fabra

  • White Papers // Feb 2011

    DCF/DSDMA: Enhanced DCF With SDMA Downlink Transmissions for WLANs

    Multi-user MIMO is a promising technology to enhance the performance of WLANs. However, the MAC protocol of the IEEE 802.11 standard (the DCF MAC protocol) is not able to solve the new coordination and synchronization issues that are needed to enable multiple simultaneous transmissions. This paper presents an enhanced MAC...

    Provided By Universitat Pompeu Fabra

  • White Papers // Feb 2011

    A Comparative Survey of Adaptive Codec Solutions for VoIP Over Multirate WLANs: A Capacity Versus Quality Performance Trade-Off

    In multi-rate WLANs, users can suffer transmission rate changes due to the link adaptation mechanism. This results in a variable capacity channel, which is very hostile for VoIP and can cause serious Quality of Service (QoS) degradation in all active calls. Various codec adaptation mechanisms have been proposed as a...

    Provided By Universitat Pompeu Fabra

  • White Papers // Dec 2010

    Adverse Selection, Credit, And Efficiency: The Case Of The Missing Market

    The authors analyze a standard environment of adverse selection in credit markets. In the environment, entrepreneurs who are privately informed about the quality of their projects need to borrow in order to invest. Conventional wisdom says that, in this class of economies, the competitive equilibrium is typically inefficient. They show...

    Provided By Universitat Pompeu Fabra

  • White Papers // Sep 2010

    Generating Global Brand Equity Through Corporate Social Responsibility To Key Stakeholders

    In this paper, the authors argue that socially responsible policies have positive short-term and long-term impact on equity of global brands. They find that corporate social responsibility towards all stakeholders, whether primary (customers, shareholders, employees and suppliers) or secondary (community), have positive effects on brand equity value, where the secondary...

    Provided By Universitat Pompeu Fabra

  • White Papers // Sep 2010

    Credit Constraints, Firms~ Precautionary Investment, And The Business Cycle

    This paper studies the macroeconomic implications of firms' precautionary investment behavior in response to anticipation of future financing constraints. Firms increase their demand for liquid and safe investments in order to alleviate future borrowing constraints and decrease the probability of having to forego future profitable investment opportunities. This results in...

    Provided By Universitat Pompeu Fabra

  • White Papers // Sep 2010

    Neglected Risks, Financial Innovation, and Financial Fragility

    The authors present a standard model of financial innovation, in which intermediaries engineer securities with cash flows that investors seek, but modify two assumptions. First, investors (and possibly intermediaries) neglect certain unlikely risks. Second, investors demand securities with safe cash flows. Financial intermediaries cater to these preferences and beliefs by...

    Provided By Universitat Pompeu Fabra

  • White Papers // Jul 2010

    Dynamic Parameter Adjustment in CSMA/ECA

    CSMA/ECA is a modification of CSMA/CA that delivers higher performance by reducing the number of collisions. This paper presents an algorithm to adapt a configuration parameter of the protocol to ensure high performance for any given number of competing stations. Performance is measured in terms of efficiency and fairness. The...

    Provided By Universitat Pompeu Fabra

  • White Papers // Jul 2010

    Conglomeration With Bankruptcy Costs: Separate Or Joint Financing?

    The paper analyzes the determinants of the optimal scope of incorporation in the presence of bankruptcy costs. Bankruptcy costs alone generate a non-trivial tradeoff between the benefit of coinsurance and the cost of risk contamination associated to joint financing corporate projects through debt. This tradeoff is characterized for projects with...

    Provided By Universitat Pompeu Fabra

  • White Papers // Jul 2010

    The Impact Of Gender Composition On Team Performance And Decision-Making: Evidence From The Field

    The authors investigate whether the gender composition of teams affect their economic performance. They study a large business game, played in groups of three, where each group takes the role of a general manager. There are two parallel competitions, one involving undergraduates and the other involving MBAs. The analysis shows...

    Provided By Universitat Pompeu Fabra

  • White Papers // Jul 2010

    A Unifying Approach To The Empirical Evaluation Of Asset Pricing Models

    Two main approaches are commonly used to empirically evaluate linear factor pricing models: regression and SDF methods, with centred and uncentred versions of the latter. The authors show that unlike standard two-step or iterated GMM procedures, single-step estimators such as continuously updated GMM yield numerically identical values for prices of...

    Provided By Universitat Pompeu Fabra

  • White Papers // Jul 2010

    Rethinking The Effects Of Financial Liberalization

    During the last few decades, many emerging markets have lifted most restrictions on international asset trade. The conventional view was that capital would flow into these countries raising investment and growth; these countries would use international capital markets to smooth domestic shocks and achieve less volatile consumption; and financial integration...

    Provided By Universitat Pompeu Fabra

  • White Papers // Jun 2010

    The Dynamics Of US Inflation: Can Monetary Policy Explain The Changes?

    The authors investigate the relationship between monetary policy and inflation dynamics in the US using a medium scale structural model. The specification is estimated with Bayesian techniques and fits the data reasonably well. Policy shocks account for a part of the decline in inflation volatility; they have been less effective...

    Provided By Universitat Pompeu Fabra

  • White Papers // May 2010

    Prime Property Institutions For A Subprime Era: Exploring Innovative Models Of Residential Development And Finance

    This paper breaks new ground toward contractual and institutional innovation in models of homeownership, equity building, and mortgage enforcement. Inspired by recent developments in the affordable housing sector and in other types of public financing schemes, the authors suggest extending institutional and financial strategies such as time- and place-based division...

    Provided By Universitat Pompeu Fabra

  • White Papers // Feb 2010

    Econometrics And Decision Making: Effects Of Presentation Mode

    Much of empirical economics involves regression analysis. However, does the presentation of results affect economists' ability to make inferences for decision making purposes? In a survey, 257 academic economists were asked to make probabilistic inferences on the basis of the outputs of a regression analysis presented in a standard format....

    Provided By Universitat Pompeu Fabra

  • White Papers // Feb 2010

    A Zero-Nanosecond Time Synchronization Platform for Gigabit Ethernet Links

    Ethernet is becoming the dominant data transmission technology for service providers due to its simplicity and low cost. However, the need for Quality of Service (QoS) provisioning for some time-sensitive applications drives the definition of new functionalities in Ethernet. In this work the author's addresses QoS in Ethernet by introducing...

    Provided By Universitat Pompeu Fabra

  • White Papers // Feb 2010

    Bank Liquidity, Interbank Markets, And Monetary Policy

    A major lesson of the recent financial crisis is that the interbank lending market is crucial for banks facing large uncertainty regarding their liquidity needs. This paper studies the efficiency of the interbank lending market in allocating funds. The authors consider two different types of liquidity shocks leading to different...

    Provided By Universitat Pompeu Fabra

  • White Papers // Jan 2010

    SmsPerformer: A Real-Time Synthesis Interface for SMS

    SmsPerformer is a graphical interface for the real-time SMS synthesis engine. The application works from analyzed sounds and it has been designed to be used both as a composition and a performance tool. The program includes programmable time-varying transformations, MIDI control for the synthesis parameters, and performance loading and saving...

    Provided By Universitat Pompeu Fabra

  • White Papers // Nov 2009

    Monetary Policy In A Systemic Crisis

    This paper examines the monetary policy followed during the current financial crisis from the perspective of the theory of the lender of last resort. It is argued that standard monetary policy measures would have failed because the channels through which monetary policy is implemented depend upon the well functioning of...

    Provided By Universitat Pompeu Fabra

  • White Papers // Aug 2009

    Screening And Merger Activity

    The paper targets, by setting a reserve price, screen acquirers on their (expected) ability to generate merger-specific synergies. Both empirical evidence and many common merger models suggest that the difference between high- and low-synergy mergers becomes smaller during booms. This implies that the target's opportunity cost for sorting out relatively...

    Provided By Universitat Pompeu Fabra

  • White Papers // Aug 2009

    International Commodity Prices, Growth, And The Outbreak Of Civil War In Sub-Saharan Africa

    To learn more about the effect of economic conditions on civil war, the authors examine whether Sub-Saharan civil wars are more likely to start following downturns in the international price of countries' main export commodities. The data show a robust effect of commodity price downturns on the outbreak of the...

    Provided By Universitat Pompeu Fabra

  • White Papers // Jul 2009

    A WiMAX-Based Implementation of Network MIMO for Indoor Wireless Systems

    It is well known that Multiple-Input Multiple-Output (MIMO) techniques can bring numerous benefits, such as higher spectral efficiency, to point-to-point wireless links. More recently, there has been interest in extending MIMO concepts to multiuser wireless systems. The focus in this paper is on network MIMO, a family of techniques whereby...

    Provided By Universitat Pompeu Fabra

  • White Papers // Jul 2009

    The Impact Of Tax Credits On Labor Supply

    One of the principle aims of the Working Families' Tax Credit in the UK was to increase the participation of single mothers. The literature to date concludes there was approximately a five-percentage-point increase in employment of single mothers. The differences-in-differences methodology that is typically used compares single mother with single...

    Provided By Universitat Pompeu Fabra

  • White Papers // Jun 2009

    Decision Making In Uncertain And Changing Environments

    The authors consider an agent who has to repeatedly make choices in an uncertain and changing environment, who has full information of the past, who discounts future payoffs, but who has no prior. They provide a learning algorithm that performs almost as well as the best of a given finite...

    Provided By Universitat Pompeu Fabra

  • White Papers // Apr 2009

    A Queuing Model for the Non-Continuous Frame Assembly Scheme in Finite Buffers

    A batch-service finite-buffer queuing model for the non continuous frame assembly scheme is presented. The steady-state probabilities are computed by simply solving the bi-dimensional Markov chain which models the queueing system. However, transitions between states require to know the conditional (as it depends on each state) probability distribution of the...

    Provided By Universitat Pompeu Fabra

  • White Papers // Apr 2009

    Limited Liability And Mechanism Design In Procurement

    In the presence of cost uncertainty, limited liability introduces the possibility of default in procurement with its associated bankruptcy costs. When financial soundness is not perfectly observable, the authors show that incentive compatibility implies that financially less sound contractors are selected with higher probability in any feasible mechanism. Informational rents...

    Provided By Universitat Pompeu Fabra

  • White Papers // Mar 2009

    Flat Soft-Synchronization for Gigabit Ethernet

    This paper presents a synchronization platform for synchronizing nodes in a Gigabit Ethernet network. There are two key concepts in this paper. The first is the implementation of a hardware-assisted timestamping technique that timestamps on the-fly the inbound/outbound frames. With this technique and using a low-cost communication protocol, it is...

    Provided By Universitat Pompeu Fabra

  • White Papers // Jan 2009

    Hybrid Risk Adjustment For Pharmaceutical Benefits

    This paper analyses the application of hybrid risk adjustment versus either prospective or concurrent risk adjustment formulae in the context of funding pharmaceutical benefits for the population of an integrated healthcare delivery organization in Catalonia during years 2002 and 2003. The authors apply a mixed formula and find that a...

    Provided By Universitat Pompeu Fabra

  • White Papers // Jan 2009

    A Model Of Collateral, Investment, And Adverse Selection

    This paper characterizes the relationship between entrepreneurial wealth and aggregate investment under adverse selection. Its main finding is that such a relationship need not be monotonic. In particular, three results emerge from the analysis: pooling equilibria, in which investment is independent of entrepreneurial wealth, are more likely to arise when...

    Provided By Universitat Pompeu Fabra

  • White Papers // Jan 2009

    Credit Constraints, Firms? - Precautionary Investment, And The Business Cycle

    This paper studies how the capacity of the financial system to spread entrepreneurial risk may vary across the business cycle and identifies a novel amplification mechanism for macroeconomic shocks based on time-varying risk-sharing opportunities that affect firms' willingness to invest and their preference for the risk profile of their portfolio...

    Provided By Universitat Pompeu Fabra

  • White Papers // Jul 2009

    A WiMAX-Based Implementation of Network MIMO for Indoor Wireless Systems

    It is well known that Multiple-Input Multiple-Output (MIMO) techniques can bring numerous benefits, such as higher spectral efficiency, to point-to-point wireless links. More recently, there has been interest in extending MIMO concepts to multiuser wireless systems. The focus in this paper is on network MIMO, a family of techniques whereby...

    Provided By Universitat Pompeu Fabra

  • White Papers // Jan 2010

    SmsPerformer: A Real-Time Synthesis Interface for SMS

    SmsPerformer is a graphical interface for the real-time SMS synthesis engine. The application works from analyzed sounds and it has been designed to be used both as a composition and a performance tool. The program includes programmable time-varying transformations, MIDI control for the synthesis parameters, and performance loading and saving...

    Provided By Universitat Pompeu Fabra

  • White Papers // Mar 2009

    Flat Soft-Synchronization for Gigabit Ethernet

    This paper presents a synchronization platform for synchronizing nodes in a Gigabit Ethernet network. There are two key concepts in this paper. The first is the implementation of a hardware-assisted timestamping technique that timestamps on the-fly the inbound/outbound frames. With this technique and using a low-cost communication protocol, it is...

    Provided By Universitat Pompeu Fabra

  • White Papers // Feb 2010

    A Zero-Nanosecond Time Synchronization Platform for Gigabit Ethernet Links

    Ethernet is becoming the dominant data transmission technology for service providers due to its simplicity and low cost. However, the need for Quality of Service (QoS) provisioning for some time-sensitive applications drives the definition of new functionalities in Ethernet. In this work the author's addresses QoS in Ethernet by introducing...

    Provided By Universitat Pompeu Fabra

  • White Papers // Aug 2009

    Screening And Merger Activity

    The paper targets, by setting a reserve price, screen acquirers on their (expected) ability to generate merger-specific synergies. Both empirical evidence and many common merger models suggest that the difference between high- and low-synergy mergers becomes smaller during booms. This implies that the target's opportunity cost for sorting out relatively...

    Provided By Universitat Pompeu Fabra

  • White Papers // Apr 2009

    Limited Liability And Mechanism Design In Procurement

    In the presence of cost uncertainty, limited liability introduces the possibility of default in procurement with its associated bankruptcy costs. When financial soundness is not perfectly observable, the authors show that incentive compatibility implies that financially less sound contractors are selected with higher probability in any feasible mechanism. Informational rents...

    Provided By Universitat Pompeu Fabra

  • White Papers // Jan 2009

    Hybrid Risk Adjustment For Pharmaceutical Benefits

    This paper analyses the application of hybrid risk adjustment versus either prospective or concurrent risk adjustment formulae in the context of funding pharmaceutical benefits for the population of an integrated healthcare delivery organization in Catalonia during years 2002 and 2003. The authors apply a mixed formula and find that a...

    Provided By Universitat Pompeu Fabra

  • White Papers // Sep 2010

    Credit Constraints, Firms~ Precautionary Investment, And The Business Cycle

    This paper studies the macroeconomic implications of firms' precautionary investment behavior in response to anticipation of future financing constraints. Firms increase their demand for liquid and safe investments in order to alleviate future borrowing constraints and decrease the probability of having to forego future profitable investment opportunities. This results in...

    Provided By Universitat Pompeu Fabra

  • White Papers // Jun 2010

    The Dynamics Of US Inflation: Can Monetary Policy Explain The Changes?

    The authors investigate the relationship between monetary policy and inflation dynamics in the US using a medium scale structural model. The specification is estimated with Bayesian techniques and fits the data reasonably well. Policy shocks account for a part of the decline in inflation volatility; they have been less effective...

    Provided By Universitat Pompeu Fabra

  • White Papers // Sep 2010

    Neglected Risks, Financial Innovation, and Financial Fragility

    The authors present a standard model of financial innovation, in which intermediaries engineer securities with cash flows that investors seek, but modify two assumptions. First, investors (and possibly intermediaries) neglect certain unlikely risks. Second, investors demand securities with safe cash flows. Financial intermediaries cater to these preferences and beliefs by...

    Provided By Universitat Pompeu Fabra

  • White Papers // Dec 2010

    Adverse Selection, Credit, And Efficiency: The Case Of The Missing Market

    The authors analyze a standard environment of adverse selection in credit markets. In the environment, entrepreneurs who are privately informed about the quality of their projects need to borrow in order to invest. Conventional wisdom says that, in this class of economies, the competitive equilibrium is typically inefficient. They show...

    Provided By Universitat Pompeu Fabra

  • White Papers // Jul 2010

    Conglomeration With Bankruptcy Costs: Separate Or Joint Financing?

    The paper analyzes the determinants of the optimal scope of incorporation in the presence of bankruptcy costs. Bankruptcy costs alone generate a non-trivial tradeoff between the benefit of coinsurance and the cost of risk contamination associated to joint financing corporate projects through debt. This tradeoff is characterized for projects with...

    Provided By Universitat Pompeu Fabra

  • White Papers // Nov 2009

    Monetary Policy In A Systemic Crisis

    This paper examines the monetary policy followed during the current financial crisis from the perspective of the theory of the lender of last resort. It is argued that standard monetary policy measures would have failed because the channels through which monetary policy is implemented depend upon the well functioning of...

    Provided By Universitat Pompeu Fabra

  • White Papers // Feb 2010

    Bank Liquidity, Interbank Markets, And Monetary Policy

    A major lesson of the recent financial crisis is that the interbank lending market is crucial for banks facing large uncertainty regarding their liquidity needs. This paper studies the efficiency of the interbank lending market in allocating funds. The authors consider two different types of liquidity shocks leading to different...

    Provided By Universitat Pompeu Fabra

  • White Papers // Feb 2010

    Econometrics And Decision Making: Effects Of Presentation Mode

    Much of empirical economics involves regression analysis. However, does the presentation of results affect economists' ability to make inferences for decision making purposes? In a survey, 257 academic economists were asked to make probabilistic inferences on the basis of the outputs of a regression analysis presented in a standard format....

    Provided By Universitat Pompeu Fabra

  • White Papers // May 2010

    Prime Property Institutions For A Subprime Era: Exploring Innovative Models Of Residential Development And Finance

    This paper breaks new ground toward contractual and institutional innovation in models of homeownership, equity building, and mortgage enforcement. Inspired by recent developments in the affordable housing sector and in other types of public financing schemes, the authors suggest extending institutional and financial strategies such as time- and place-based division...

    Provided By Universitat Pompeu Fabra

  • White Papers // Jul 2010

    The Impact Of Gender Composition On Team Performance And Decision-Making: Evidence From The Field

    The authors investigate whether the gender composition of teams affect their economic performance. They study a large business game, played in groups of three, where each group takes the role of a general manager. There are two parallel competitions, one involving undergraduates and the other involving MBAs. The analysis shows...

    Provided By Universitat Pompeu Fabra

  • White Papers // Jul 2010

    A Unifying Approach To The Empirical Evaluation Of Asset Pricing Models

    Two main approaches are commonly used to empirically evaluate linear factor pricing models: regression and SDF methods, with centred and uncentred versions of the latter. The authors show that unlike standard two-step or iterated GMM procedures, single-step estimators such as continuously updated GMM yield numerically identical values for prices of...

    Provided By Universitat Pompeu Fabra

  • White Papers // Aug 2009

    International Commodity Prices, Growth, And The Outbreak Of Civil War In Sub-Saharan Africa

    To learn more about the effect of economic conditions on civil war, the authors examine whether Sub-Saharan civil wars are more likely to start following downturns in the international price of countries' main export commodities. The data show a robust effect of commodity price downturns on the outbreak of the...

    Provided By Universitat Pompeu Fabra

  • White Papers // Jul 2009

    The Impact Of Tax Credits On Labor Supply

    One of the principle aims of the Working Families' Tax Credit in the UK was to increase the participation of single mothers. The literature to date concludes there was approximately a five-percentage-point increase in employment of single mothers. The differences-in-differences methodology that is typically used compares single mother with single...

    Provided By Universitat Pompeu Fabra

  • White Papers // Jun 2009

    Decision Making In Uncertain And Changing Environments

    The authors consider an agent who has to repeatedly make choices in an uncertain and changing environment, who has full information of the past, who discounts future payoffs, but who has no prior. They provide a learning algorithm that performs almost as well as the best of a given finite...

    Provided By Universitat Pompeu Fabra

  • White Papers // Sep 2010

    Generating Global Brand Equity Through Corporate Social Responsibility To Key Stakeholders

    In this paper, the authors argue that socially responsible policies have positive short-term and long-term impact on equity of global brands. They find that corporate social responsibility towards all stakeholders, whether primary (customers, shareholders, employees and suppliers) or secondary (community), have positive effects on brand equity value, where the secondary...

    Provided By Universitat Pompeu Fabra

  • White Papers // Jul 2010

    Rethinking The Effects Of Financial Liberalization

    During the last few decades, many emerging markets have lifted most restrictions on international asset trade. The conventional view was that capital would flow into these countries raising investment and growth; these countries would use international capital markets to smooth domestic shocks and achieve less volatile consumption; and financial integration...

    Provided By Universitat Pompeu Fabra

  • White Papers // Jan 2009

    A Model Of Collateral, Investment, And Adverse Selection

    This paper characterizes the relationship between entrepreneurial wealth and aggregate investment under adverse selection. Its main finding is that such a relationship need not be monotonic. In particular, three results emerge from the analysis: pooling equilibria, in which investment is independent of entrepreneurial wealth, are more likely to arise when...

    Provided By Universitat Pompeu Fabra

  • White Papers // Jul 2011

    Accelerating Into The Abyss: Financial Dependence And The Great Depression

    The author's paper provides empirical support for the importance of financial distress in the propagation of the Great Depression. Even those in agreement are not unanimous in the mechanisms they propose. Friedman and Schwartz (1963) argue that bank failures caused money supply reductions which in turn depressed economic activity, while...

    Provided By Universitat Pompeu Fabra

  • White Papers // Apr 2011

    An Approximate Queueing Model for Multi-Rate Multi-User MIMO Systems

    A queueing model for multi-rate multi-user MIMO systems is presented. The model is built upon the assumption that the probability distribution of available destinations among the buffered frames at the Base Station (BS) is approximately the same as the probability distribution of the traffic arriving to the BS, this is,...

    Provided By Universitat Pompeu Fabra

  • White Papers // Feb 2011

    DCF/DSDMA: Enhanced DCF With SDMA Downlink Transmissions for WLANs

    Multi-user MIMO is a promising technology to enhance the performance of WLANs. However, the MAC protocol of the IEEE 802.11 standard (the DCF MAC protocol) is not able to solve the new coordination and synchronization issues that are needed to enable multiple simultaneous transmissions. This paper presents an enhanced MAC...

    Provided By Universitat Pompeu Fabra

  • White Papers // Jul 2010

    Dynamic Parameter Adjustment in CSMA/ECA

    CSMA/ECA is a modification of CSMA/CA that delivers higher performance by reducing the number of collisions. This paper presents an algorithm to adapt a configuration parameter of the protocol to ensure high performance for any given number of competing stations. Performance is measured in terms of efficiency and fairness. The...

    Provided By Universitat Pompeu Fabra

  • White Papers // Apr 2009

    A Queuing Model for the Non-Continuous Frame Assembly Scheme in Finite Buffers

    A batch-service finite-buffer queuing model for the non continuous frame assembly scheme is presented. The steady-state probabilities are computed by simply solving the bi-dimensional Markov chain which models the queueing system. However, transitions between states require to know the conditional (as it depends on each state) probability distribution of the...

    Provided By Universitat Pompeu Fabra

  • White Papers // Jan 2009

    Credit Constraints, Firms? - Precautionary Investment, And The Business Cycle

    This paper studies how the capacity of the financial system to spread entrepreneurial risk may vary across the business cycle and identifies a novel amplification mechanism for macroeconomic shocks based on time-varying risk-sharing opportunities that affect firms' willingness to invest and their preference for the risk profile of their portfolio...

    Provided By Universitat Pompeu Fabra

  • White Papers // Feb 2011

    A Comparative Survey of Adaptive Codec Solutions for VoIP Over Multirate WLANs: A Capacity Versus Quality Performance Trade-Off

    In multi-rate WLANs, users can suffer transmission rate changes due to the link adaptation mechanism. This results in a variable capacity channel, which is very hostile for VoIP and can cause serious Quality of Service (QoS) degradation in all active calls. Various codec adaptation mechanisms have been proposed as a...

    Provided By Universitat Pompeu Fabra

  • White Papers // Jan 2012

    On the Limitations of Cooperation in Wireless Networks

    Cooperation in a large wireless network (such as a cellular system) is shown to have certain fundamental limitations: namely, even perfect cooperation cannot in general change an interference-limited network to a noise-limited one. In contrast to existing literature that routinely assumes that the spectral efficiency scales with log P as...

    Provided By Universitat Pompeu Fabra