Universitat Politecnica de Catalunya

Displaying 1-40 of 58 results

  • White Papers // Apr 2013

    Big Data or Right Data?

    Big data now-a-days is a fashionable topic, independently of what people mean when they use this term. The challenges include how to capture, transfer, store, clean, analyze, filter, search, share, and visualize such data. But being big is just a matter of volume, although there is no clear agreement in...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Mar 2013

    Future Evolution of CSMA Protocols for the IEEE 802.11 Standard

    In this paper a candidate protocol to replace the prevalent CSMA/CA medium access control in wireless local area networks is presented. The proposed protocol can achieve higher throughput than CSMA/CA, while maintaining fairness, and without additional implementation complexity. Under certain circumstances, it is able to reach and maintain collision-free operation,...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Dec 2012

    Localization Procedure for Randomly Deployed Wireless Sensor Networks

    Wireless Sensor Networks (WSNs) are composed of nodes that gather metrics like temperature, pollution or pressure from events generated by external entities. Localization in WSNs is paramount, given that the collected metrics must be related to the place of occurrence. This paper presents an alternative way towards localization in randomly...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Jan 2012

    Real-Time Services in EPON

    This paper proposes an improved scheduling algorithm that optimizes the allocation of the real-time services and elastic flows in EPON by spreading the real-time service periods lowering the delay and thus fulfilling the QoS requirements. Among the different PON technologies the Ethernet-PON (EPON) is one of the most promising alternatives...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Sep 2011

    A Framework Based on a Fittingness Factor to Enable Efficient Exploitation of Spectrum Opportunities in Cognitive Radio Networks

    In order to increase CRs (Cognitive Radios) operation efficiency, there has been an interest in increasing awareness level about spectrum utilisation. In this respect, this paper proposes a new fittingness factor concept that captures the suitability of spectral resources exhibiting time-varying characteristics to support a set of heterogeneous CR applications....

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Sep 2011

    A Real-Time FPGA-Based Mobile WiMAX Transceiver Supporting Multi-Antenna Configurations

    This paper presents the design, implementation and experimental validation of a real-time FPGA-based mobile WiMAX baseband transceiver. Three different antenna configuration schemes were implemented and tested, namely the Single Input Single Output (SISO), the Single Input Multiple Output (SIMO) and the Multiple Input Multiple Output (MIMO). A reproducible design methodology...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Sep 2011

    On the Role of Spectrum Selection to Improve Coverage Extension Through Opportunistic Networks

    This paper discusses the role played by Opportunistic Networks (ONs) as a means to bring Future Internet services to users in different situations. After the identification of technical challenges associated to the operation of ONs the paper focuses on their applicability in the coverage extension of a wireless network. In...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Aug 2011

    Adaptive Scheduling on Power-Aware Managed Data-Centers Using Machine Learning

    Energy-related costs have become one of the major economic factors in IT data-centers, and companies and the research community are currently working on new efficient power-aware resource management strategies, also known as "Green IT". Here the authors propose a framework for autonomic scheduling of tasks and web-services on cloud environments,...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Jul 2011

    Strengthening Radio Environment Maps With Primary-User Statistical Patterns for Enhancing Cognitive Radio Operation

    In order to increase spectrum utilization efficiency, CRs (Cognitive Radios) have been introduced to reuse white spaces left unused by legacy services under the strict constraint of not interfering them. In order to fulfill this constraint while optimising spectrum utilisation, it is important to get knowledge about primary-user activity in...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Jun 2011

    Resource Allocation in Multi-Antenna MAC Networks: FBMC Vs OFDM

    This paper addresses the problem of resource allocation in a multiple access channel where several Mobile Terminals (MT's) are transmitting simultaneously to a single receiving base station, all of them with multiple antennas and exploiting beamforming. A multi-carrier modulation is assumed, either Orthogonal Frequency Division Multiplexing (OFDM) or Filter Bank...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Apr 2011

    A Novel Spectrum Selection Strategy for Matching Multi-Service Secondary Traffic to Heterogeneous Primary Spectrum Opportunities

    In order to increase spectrum utilization efficiency, CRs (Cognitive Radios) have been introduced to reuse white spaces left unused by legacy services under the strict constraint of not interfering them. In this context, this paper proposes to exploit the statistical characterization of Primary User (PU) activity to be retained in...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Apr 2011

    Recent Advances in Burst Mode Communications for Extended Fiber-to-the-Home Networks

    In this paper, the authors present recent advances in burst mode operation for WDM/TDM networks, focusing on mitigation techniques implemented at the ONU, as well as ONUONU cross-streaming. Direct communication between ONUs are experimentally demonstrated with a tunable MG-Y laser in a ring+tree PON for 640 users, without passing electrically...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Feb 2011

    Transmit and Receive Filters for MISO FBMC Systems Subjected to Power Constraints

    Build upon the OFDM/OQAM scheme this paper addresses the design of linear transmit and receive filters. Aiming at enhancing the robustness against multipath fading, two novel techniques are proposed. The first one jointly designs transmit and receive filters under the MMSE criterion. The second scheme follows a ZF approach. In...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Feb 2011

    Towards a Cooperative Intrusion Detection System for Cognitive Radio Networks

    Cognitive Radio Networks (CRNs) arise as a promising solution to the scarcity of spectrum. By means of cooperation and smart decisions influenced by previous knowledge, CRNs are able to detect and profit from the best spectrum opportunities without interfering primary licensed users. However, besides the well-known attacks to wireless networks,...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Jan 2011

    Revocable Attribute-Based Signatures With Adaptive Security in the Standard Model

    An attribute-based signature with respect to a signing policy, chosen ad-hoc by the signer, convinces the verifier that the signer holds a subset of attributes satisfying that signing policy. Ideally, the verifier must obtain no other information about the identity of the signer or the attributes he holds. This primitive...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Jan 2011

    Structured-Content Extraction From the Web for Bibliographic Reference Generation

    In this paper the authors present a system that automatically creates bibliographic indexes from a collection of PDF files by using the file contents to search the Web and later extract the information from the resulting pages. The authors pay special attention to the techniques used for extracting this data...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Jan 2011

    A Novel Impairment Aware RWA Algorithm With Consideration for QoT Estimation Inaccuracy

    In all-optical networks the physical layer impairments accumulate along a lightpath and also vary dynamically, and a number of Impairment Aware Routing and Wavelength Assignment (IA-RWA) techniques have been proposed in order to mitigate the physical layer impairments and find lightpaths that meet a required Quality of Transmission (QoT) constraint...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Jan 2011

    Using UML for Modelling the Static Part of a Software Process

    The authors study in this paper the use of UML as a tool for modeling the process of software construction. As a case study, they deal with the process of building a library of software components. UML is used in order to define the static part of the process, i.e.,...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Dec 2010

    Cross-Talk Effects on the Regenerator Allocation Optimization

    This paper studies the impact of considering crosstalk effects in the IA-RWA process and in the regenerator allocation algorithms. First of all, the authors evaluate if the regenerator allocation optimization is still useful when the crosstalk effects are considered. For this end they improve a simple physical model which computes...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Jul 2010

    Modeling the Lion Attack in Cognitive Radio Networks

    Cognitive radio is a promising technology aiming to improve the utilization of the radio electromagnetic spectrum. A cognitive radio is a smart device which runs radio applications software to perform signal processing. The use of this software enables the device to sense and understand its environment and actively change its...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Jul 2010

    OLSRp: Predicting Control Information to Achieve Scalability in OLSR Ad-Hocs Networks

    Scalability is a key design challenge that routing protocols for ad hoc networks must properly address to maintain the network performance when the number of nodes increases. This paper focusses on this issue by reducing the amount of control information messages that a link state proactive routing algorithm introduces to...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Jul 2010

    On the Physical Impairments Constraint in OBS Networks

    The introduction of sub-wavelength switching is one of the main objectives of the future transparent optical mesh networks. One strong candidate is Optical Burst Switching (OBS) which improves the resource utilisation by setting up very short lived circuits (bursts). Nonetheless, introducing optical transparency in the optical layer has an important...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Jul 2010

    A Novel Offline Physical Layer Impairments Aware RWA Algorithm With Dedicated Path Protection Consideration

    Physical layer impairments accumulate as light propagates through a lightpath in the transparent optical networks. Therefore it is possible to provision a lightpath, while its Quality of Transmission (QoT) does not meet the required threshold. Considering the physical layer impairments in the network planning phase gives rise to a set...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Jun 2010

    Energy-Delay Tradeoff Analysis in Embedded M2M Networks With Channel Coding

    Machine-To-Machine (M2M), an emerging communications paradigm, is a facilitator of data flows between machines used, e.g., in mission-critical applications. Focusing in this paper on embedded multi-hop M2M implementations with myopic routing, a prime design aim is to jointly minimize energy expenditure and the end-to-end delay whilst not jeopardizing the network's...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // May 2010

    Performance and Overhead Analysis of the ALOE Middleware for SDR

    Current Software-Defined Radio applications (Waveforms) are tailored to specific hardware. Processor vendors frequently adapt internal OS mechanisms for its specific architecture (e.g. Scheduling and Synchronization). The Abstraction Layer and Operating Environment (ALOE) is an open source SDR operating environment that isolates platform architecture from the application design. An integrated resource...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Apr 2010

    TOA Estimation in UWB: Comparison Between Time and Frequency Domain Processing

    A comparison between time and frequency domain TOA estimators compliant with the 802.15.4a Standard has been made. The time domain estimator is done in two stages. One has the goal of identify the first pulse in each symbol interval and the other aims to acquire the start of frame delimiter....

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Apr 2010

    Multi-Radio Cooperative ARQ in Wireless Cellular Networks: A MAC Layer Perspective

    Multi-Radio Cooperative Automatic Retransmission ReQuest (MCARQ) schemes are introduced in this paper within the context of hybrid networks which combine long-range and short-range communications. Since the number of wireless devices is incessantly increasing, it is frequently possible to establish a spontaneous cooperative cluster in the close proximity of any wireless...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Mar 2010

    Ideal Multipartite Secret Sharing Schemes

    Multipartite secret sharing schemes are those having a multipartite access structure, in which the set of participants is divided into several parts and all participants in the same part play an equivalent role. In this paper, the characterization of ideal multipartite access structures is studied with all generality. The results...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Feb 2010

    Towards Energy-Aware Scheduling in Data Centers Using Machine Learning

    As energy-related costs have become a major economical factor for IT infrastructures and data-centers, companies and the research community are being challenged to find better and more efficient power-aware resource management strategies. There is a growing interest in "Green" IT and there is still a big gap in this area...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Feb 2010

    Coexistence of a Novel Medium Access Control Protocol for Wireless Ad Hoc Networks and the IEEE 802.11

    The authors describe in this paper a methodology to facilitate the coexistence of the Distributed Queuing Medium Access Control (MAC) protocol for Ad hoc Networks (DQMAN) with the IEEE 802.11 Standard MAC protocol. By using dual terminals which can operate with the two MAC protocols, it is possible to run...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Jan 2010

    The Hiring Problem: An Analytic And Experimental Study

    When a small, start-up company intends to grow, it has to hire employees. Because the company requires high quality staff, the employer has to interview a lot of candidates and thus, she may take long time to collect the required staff. Of course, there is another important demand which is...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Dec 2009

    Elastic Management of Tasks in Virtualized Environments

    Nowadays, service providers in the Cloud offer complex services ready to be used as it was a commodity like water or electricity to their customers. A key technology for this approach is virtualization which facilitates provider's management and provides on-demand virtual environments, which are isolated and consolidated in order to...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Dec 2009

    The Effects of Optimized Regenerator Allocation in Translucent Networks Under Inaccurate Physical information

    Optimized regenerator allocation techniques select which of the already installed regenerators in a translucent network must be used in order to maximize the quality of the optical signal while minimizing the opaqueness of the network. Unfortunately, the performance of an optimized regenerator allocation strategy strongly depends on the accuracy of...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Dec 2009

    Insights on the Internet Routing Scalability Issues

    In recent years, the size and dynamics of the global routing table have increased rapidly along with an increase in the number of edge networks. The relation between edge network quantity and routing table size/dynamics reveals a major limitation in the current architecture. This paper introduces the two problematics target...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Nov 2009

    Reinforcement Learning for Dynamic Spectrum Management in WCDMA

    Low use of licensed spectrum imposes a need for the advanced spectrum management for wise spectrum usage with the release of unneeded frequency bands for the secondary markets and opportunistic access. In this paper, the authors present the possibilities to apply reinforcement learning in WCDMA to enable the autonomous decision...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Sep 2009

    A Cross-Layer Scheduling Strategy for the Downlink of a MIMO-OFDMA System With Heterogeneous Traffic

    In this paper, the authors propose and investigate a cross-layer multiuser scheduling strategy for the support of heterogeneous traffic in the downlink of a MIMO-OFDMA system. It jointly considers different objectives: maximize the sum-rate on the radio channel, ensure a fair allocation of resources among users belonging to the same...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Aug 2009

    Analytical Evaluation of a Medium Access Control Priority Mechanism for Wireless Ad Hoc Networks

    The authors present in this paper the analytical evaluation of a simple mechanism to reduce the average transmission delay of master stations in a network based on the Distributed Queuing MAC protocol for Ad hoc Networks (DQMAN). When DQMAN is executed, the network is self-organized into dynamic and spontaneous master-slave...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Aug 2009

    Handoff Functions for a Distributed Queuing Collision Avoidance Medium Access Control Protocol for Wireless LANs

    The Distributed Queuing with Collision Avoidance (DQCA) Medium Access Control (MAC) protocol has been presented in the literature as a high-performance protocol for up-link traffic in WLANs. Previous works regarding DQCA are focused on the operation of a single cell, where no interaction with neighboring sites is considered. In this...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Jul 2009

    Positioning-Based Framework for Secondary Spectrum Usage

    In this paper, the authors introduce a framework encompassing the creation and the exploitation of secondary spectrum usage opportunities. The paper develops a complete positioning-based framework to assess the feasibility of supporting secondary communications on frequencies which are released by primary spectrum management methodologies. In particular, the paper analyzes four...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Jun 2009

    On the Challenges of Finding Two Linkdisjoint Lightpaths of Minimum Total Weight Across an Optical Network

    The problem of finding two link-disjoint (primary and backup) paths of minimum total weight across a network is referred to as Problem 2DP. For this problem, there exist computationally efficient solving algorithms such as the one developed by Suurballe and Tarjan. Indeed, the latter has become the reference algorithm for...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Dec 2009

    The Effects of Optimized Regenerator Allocation in Translucent Networks Under Inaccurate Physical information

    Optimized regenerator allocation techniques select which of the already installed regenerators in a translucent network must be used in order to maximize the quality of the optical signal while minimizing the opaqueness of the network. Unfortunately, the performance of an optimized regenerator allocation strategy strongly depends on the accuracy of...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Jun 2009

    On the Challenges of Finding Two Linkdisjoint Lightpaths of Minimum Total Weight Across an Optical Network

    The problem of finding two link-disjoint (primary and backup) paths of minimum total weight across a network is referred to as Problem 2DP. For this problem, there exist computationally efficient solving algorithms such as the one developed by Suurballe and Tarjan. Indeed, the latter has become the reference algorithm for...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Jun 2008

    Distributed Sampling for On-line SLA Assessment

    New business infrastructures over the Internet pose a new set of traffic constraints. In particular, multimedia and interactive contents require guarantees of bandwidth and delivery time. The broad deployment and real-time nature of this class of applications require the provisioning of specific resources in the network to guarantee a certain...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Jan 2011

    A Novel Impairment Aware RWA Algorithm With Consideration for QoT Estimation Inaccuracy

    In all-optical networks the physical layer impairments accumulate along a lightpath and also vary dynamically, and a number of Impairment Aware Routing and Wavelength Assignment (IA-RWA) techniques have been proposed in order to mitigate the physical layer impairments and find lightpaths that meet a required Quality of Transmission (QoT) constraint...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Jul 2010

    A Novel Offline Physical Layer Impairments Aware RWA Algorithm With Dedicated Path Protection Consideration

    Physical layer impairments accumulate as light propagates through a lightpath in the transparent optical networks. Therefore it is possible to provision a lightpath, while its Quality of Transmission (QoT) does not meet the required threshold. Considering the physical layer impairments in the network planning phase gives rise to a set...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Aug 2011

    Adaptive Scheduling on Power-Aware Managed Data-Centers Using Machine Learning

    Energy-related costs have become one of the major economic factors in IT data-centers, and companies and the research community are currently working on new efficient power-aware resource management strategies, also known as "Green IT". Here the authors propose a framework for autonomic scheduling of tasks and web-services on cloud environments,...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Jun 2009

    A Max Coverage Formulation for Information Dissemination in Vehicular Networks

    The authors consider that k infrastructured nodes have to be deployed for disseminating information to vehicles travelling in an urban area. They name the infrastructure nodes Dissemination Points (DPs) and formulate their problem as a Maximum Coverage Problem (MCP) so as to maximize the number of vehicles that get in...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Apr 2011

    Recent Advances in Burst Mode Communications for Extended Fiber-to-the-Home Networks

    In this paper, the authors present recent advances in burst mode operation for WDM/TDM networks, focusing on mitigation techniques implemented at the ONU, as well as ONUONU cross-streaming. Direct communication between ONUs are experimentally demonstrated with a tunable MG-Y laser in a ring+tree PON for 640 users, without passing electrically...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Jun 2011

    Resource Allocation in Multi-Antenna MAC Networks: FBMC Vs OFDM

    This paper addresses the problem of resource allocation in a multiple access channel where several Mobile Terminals (MT's) are transmitting simultaneously to a single receiving base station, all of them with multiple antennas and exploiting beamforming. A multi-carrier modulation is assumed, either Orthogonal Frequency Division Multiplexing (OFDM) or Filter Bank...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Feb 2011

    Transmit and Receive Filters for MISO FBMC Systems Subjected to Power Constraints

    Build upon the OFDM/OQAM scheme this paper addresses the design of linear transmit and receive filters. Aiming at enhancing the robustness against multipath fading, two novel techniques are proposed. The first one jointly designs transmit and receive filters under the MMSE criterion. The second scheme follows a ZF approach. In...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Sep 2009

    A Cross-Layer Scheduling Strategy for the Downlink of a MIMO-OFDMA System With Heterogeneous Traffic

    In this paper, the authors propose and investigate a cross-layer multiuser scheduling strategy for the support of heterogeneous traffic in the downlink of a MIMO-OFDMA system. It jointly considers different objectives: maximize the sum-rate on the radio channel, ensure a fair allocation of resources among users belonging to the same...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Jun 2009

    UWB Joint TOA and DOA Estimation

    This paper deals with the simultaneous estimation of Time Of Arrival (TOA) and Direction Of Arrival (DOA) in UWB systems considering multipath propagation. The estimation is performed in the frequency domain by computing a two dimensional power delay-angle spectrum based on the periodogram because of its low computational complexity. High...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Apr 2010

    TOA Estimation in UWB: Comparison Between Time and Frequency Domain Processing

    A comparison between time and frequency domain TOA estimators compliant with the 802.15.4a Standard has been made. The time domain estimator is done in two stages. One has the goal of identify the first pulse in each symbol interval and the other aims to acquire the start of frame delimiter....

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Feb 2009

    A Low Complexity Space-Frequency Multiuser Scheduling Algorithm

    This paper presents a resource allocation algorithm in K-user, M-subcarrier and NT-antenna systems for on-line scheduling. To exploit temporal diversity and to reduce complexity, the ergodic sum rate is maximized instead of the instantaneous one. Dual optimization is applied to further diminish complexity together with a stochastic approximation, which is...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Feb 2009

    Differential Feedback in MIMO Communications: Performance With Delay and Real Channel Measurements

    This paper studies the performance of the authors' recently proposed differential feedback scheme for Multi-Input-Multi-Output (MIMO) communication systems using real channel measurement data. The algorithm is applied to the channel correlation matrix exploiting geodesic curves and the intrinsic geometry of positive definite Hermitian matrices. The performance of this and a...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Jul 2010

    On the Physical Impairments Constraint in OBS Networks

    The introduction of sub-wavelength switching is one of the main objectives of the future transparent optical mesh networks. One strong candidate is Optical Burst Switching (OBS) which improves the resource utilisation by setting up very short lived circuits (bursts). Nonetheless, introducing optical transparency in the optical layer has an important...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Aug 2008

    A Survey of Routing Protocols for Maximizing the Lifetime of Ad Hoc Wireless Networks

    This paper is to show, how to maximize the useful lifetime of ad hoc wireless networks through energy-efficient routing. Most of the studies on energy-aware routing protocols do not provide clear-cut notions about a network's lifetime and therefore there is a lack of clear objectives in the design of algorithms....

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Jan 2012

    Real-Time Services in EPON

    This paper proposes an improved scheduling algorithm that optimizes the allocation of the real-time services and elastic flows in EPON by spreading the real-time service periods lowering the delay and thus fulfilling the QoS requirements. Among the different PON technologies the Ethernet-PON (EPON) is one of the most promising alternatives...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Dec 2012

    Localization Procedure for Randomly Deployed Wireless Sensor Networks

    Wireless Sensor Networks (WSNs) are composed of nodes that gather metrics like temperature, pollution or pressure from events generated by external entities. Localization in WSNs is paramount, given that the collected metrics must be related to the place of occurrence. This paper presents an alternative way towards localization in randomly...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Sep 2011

    On the Role of Spectrum Selection to Improve Coverage Extension Through Opportunistic Networks

    This paper discusses the role played by Opportunistic Networks (ONs) as a means to bring Future Internet services to users in different situations. After the identification of technical challenges associated to the operation of ONs the paper focuses on their applicability in the coverage extension of a wireless network. In...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Sep 2011

    A Framework Based on a Fittingness Factor to Enable Efficient Exploitation of Spectrum Opportunities in Cognitive Radio Networks

    In order to increase CRs (Cognitive Radios) operation efficiency, there has been an interest in increasing awareness level about spectrum utilisation. In this respect, this paper proposes a new fittingness factor concept that captures the suitability of spectral resources exhibiting time-varying characteristics to support a set of heterogeneous CR applications....

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Apr 2011

    A Novel Spectrum Selection Strategy for Matching Multi-Service Secondary Traffic to Heterogeneous Primary Spectrum Opportunities

    In order to increase spectrum utilization efficiency, CRs (Cognitive Radios) have been introduced to reuse white spaces left unused by legacy services under the strict constraint of not interfering them. In this context, this paper proposes to exploit the statistical characterization of Primary User (PU) activity to be retained in...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Jul 2011

    Strengthening Radio Environment Maps With Primary-User Statistical Patterns for Enhancing Cognitive Radio Operation

    In order to increase spectrum utilization efficiency, CRs (Cognitive Radios) have been introduced to reuse white spaces left unused by legacy services under the strict constraint of not interfering them. In order to fulfill this constraint while optimising spectrum utilisation, it is important to get knowledge about primary-user activity in...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Aug 2009

    Handoff Functions for a Distributed Queuing Collision Avoidance Medium Access Control Protocol for Wireless LANs

    The Distributed Queuing with Collision Avoidance (DQCA) Medium Access Control (MAC) protocol has been presented in the literature as a high-performance protocol for up-link traffic in WLANs. Previous works regarding DQCA are focused on the operation of a single cell, where no interaction with neighboring sites is considered. In this...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Aug 2009

    Analytical Evaluation of a Medium Access Control Priority Mechanism for Wireless Ad Hoc Networks

    The authors present in this paper the analytical evaluation of a simple mechanism to reduce the average transmission delay of master stations in a network based on the Distributed Queuing MAC protocol for Ad hoc Networks (DQMAN). When DQMAN is executed, the network is self-organized into dynamic and spontaneous master-slave...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Jun 2010

    Energy-Delay Tradeoff Analysis in Embedded M2M Networks With Channel Coding

    Machine-To-Machine (M2M), an emerging communications paradigm, is a facilitator of data flows between machines used, e.g., in mission-critical applications. Focusing in this paper on embedded multi-hop M2M implementations with myopic routing, a prime design aim is to jointly minimize energy expenditure and the end-to-end delay whilst not jeopardizing the network's...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Feb 2010

    Coexistence of a Novel Medium Access Control Protocol for Wireless Ad Hoc Networks and the IEEE 802.11

    The authors describe in this paper a methodology to facilitate the coexistence of the Distributed Queuing Medium Access Control (MAC) protocol for Ad hoc Networks (DQMAN) with the IEEE 802.11 Standard MAC protocol. By using dual terminals which can operate with the two MAC protocols, it is possible to run...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Apr 2010

    Multi-Radio Cooperative ARQ in Wireless Cellular Networks: A MAC Layer Perspective

    Multi-Radio Cooperative Automatic Retransmission ReQuest (MCARQ) schemes are introduced in this paper within the context of hybrid networks which combine long-range and short-range communications. Since the number of wireless devices is incessantly increasing, it is frequently possible to establish a spontaneous cooperative cluster in the close proximity of any wireless...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Dec 2010

    Cross-Talk Effects on the Regenerator Allocation Optimization

    This paper studies the impact of considering crosstalk effects in the IA-RWA process and in the regenerator allocation algorithms. First of all, the authors evaluate if the regenerator allocation optimization is still useful when the crosstalk effects are considered. For this end they improve a simple physical model which computes...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Oct 2008

    Design and Implementation on DSP of the ETSI GSM Adaptive Multi-Rate Vocoder

    With the current focus on high-speed packet data transmission, it is easy to forget that the primary purpose of GSM digital telecommunication systems was speech transmission. The general perception is that the complexity of the overall system is associated with the management of the transmission link. However, there is a...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Jun 2009

    Adaptive XML Tree Classification on Evolving Data Streams

    This paper proposes a new method to classify patterns, using closed and maximal frequent patterns as features. Generally, classification requires a previous mapping from the patterns to classify to vectors of features, and frequent patterns have been used as features in the past. Closed patterns maintain the same information as...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // May 2010

    Performance and Overhead Analysis of the ALOE Middleware for SDR

    Current Software-Defined Radio applications (Waveforms) are tailored to specific hardware. Processor vendors frequently adapt internal OS mechanisms for its specific architecture (e.g. Scheduling and Synchronization). The Abstraction Layer and Operating Environment (ALOE) is an open source SDR operating environment that isolates platform architecture from the application design. An integrated resource...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Dec 2009

    Insights on the Internet Routing Scalability Issues

    In recent years, the size and dynamics of the global routing table have increased rapidly along with an increase in the number of edge networks. The relation between edge network quantity and routing table size/dynamics reveals a major limitation in the current architecture. This paper introduces the two problematics target...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Jul 2010

    OLSRp: Predicting Control Information to Achieve Scalability in OLSR Ad-Hocs Networks

    Scalability is a key design challenge that routing protocols for ad hoc networks must properly address to maintain the network performance when the number of nodes increases. This paper focusses on this issue by reducing the amount of control information messages that a link state proactive routing algorithm introduces to...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Dec 2008

    Monitoring Adaptable SOA-Systems Using SALMon

    Adaptability is a key feature of Service-Oriented Architecture (SOA) Systems. These systems must evolve themselves in order to ensure their initial requirements as well as to satisfy arising new ones. In SOA Systems there are a lot of dependencies between services, but each service is an independent element of the...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Jan 2011

    Using UML for Modelling the Static Part of a Software Process

    The authors study in this paper the use of UML as a tool for modeling the process of software construction. As a case study, they deal with the process of building a library of software components. UML is used in order to define the static part of the process, i.e.,...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Jan 2011

    Revocable Attribute-Based Signatures With Adaptive Security in the Standard Model

    An attribute-based signature with respect to a signing policy, chosen ad-hoc by the signer, convinces the verifier that the signer holds a subset of attributes satisfying that signing policy. Ideally, the verifier must obtain no other information about the identity of the signer or the attributes he holds. This primitive...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Feb 2009

    Analysis of Bandwidth Measurement Methodologies Over WLAN Systems

    WLAN devices have become a fundamental component of nowadays network deployments. However, even though traditional networking applications run mostly unchanged over wireless links, the actual interaction between these applications and the dynamics of wireless transmissions is not yet fully understood. An important example of such applications are bandwidth estimation tools....

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Mar 2010

    Ideal Multipartite Secret Sharing Schemes

    Multipartite secret sharing schemes are those having a multipartite access structure, in which the set of participants is divided into several parts and all participants in the same part play an equivalent role. In this paper, the characterization of ideal multipartite access structures is studied with all generality. The results...

    Provided By Universitat Politecnica de Catalunya

  • White Papers // Jun 2009

    On Secret Sharing Schemes, Matroids and Polymatroids

    The complexity of a secret sharing scheme is defined as the ratio between the maximum length of the shares and the length of the secret. The optimization of this parameter for general access structures is an important and very difficult open problem in secret sharing. The authors explore in this...

    Provided By Universitat Politecnica de Catalunya