Instituto de Telecomunicacoes

Displaying 1-17 of 17 results

  • White Papers // May 2012

    Anomaly Detection Using DSNS and Firefly Harmonic Clustering Algorithm

    The networks are becoming an essential part of society life and anomalies may represent a loss in network performance. Modeling the traffic behavior pattern is possible to predict the behavior expected and characterize an anomaly. The authors proposed a hybrid clustering algorithm, Firefly Harmonic Clustering Algorithm (FHCA), for network volume...

    Provided By Instituto de Telecomunicacoes

  • White Papers // May 2012

    On-Demand Selection, Control and Management of Context-Based Wireless Mesh Networks

    The flexible infrastructure of Wireless Mesh Networks (WMNs) can be exploited to provide support to emerging communication paradigms. In this paper, the authors consider an architecture of context-based virtual WMNs, where the context requirements and preferences of mesh clients are the driving force to dynamically create and configure, through network...

    Provided By Instituto de Telecomunicacoes

  • White Papers // May 2012

    Energy Saving Through Cooperation Using Game Theory-Based Trading Model

    Recent years have witnessed an explosive growth of wireless technologies and applications. The adoption of a wide range of multimedia applications on wireless devices has been made possible through the advances in wireless technologies. Only one aspect is not catching up, which is re-chargeable battery for mobile devices. Without disruptive...

    Provided By Instituto de Telecomunicacoes

  • White Papers // Jan 2012

    Iterative Decoding and Channel Estimation of MIMO-OFDM Transmissions With Hierarchical Constellations and Implict Pilots

    It is widely recognized that OFDM modulations (Orthogonal Frequency Division Multiplexing) are suitable for broadband wireless systems. For this reason they were selected for several digital broadcast systems and wireless networks and are being considered for UTRA (Universal Mobile Telecommunications System Terrestrial Radio Access) Long-Term Evolution (LTE). Regarding LTE UTRA,...

    Provided By Instituto de Telecomunicacoes

  • White Papers // Sep 2011

    FEBER: Feedback Based Erasure Recovery for Real-Time Multicast Over 802.11 Networks

    The authors consider the problem of broadcasting data streams over a wireless network for multiple receivers with reliability and timely delivery guarantees. In their framework, they consider packets that need to be delivered within a given time interval, after which the packet is no longer useful at the application layer....

    Provided By Instituto de Telecomunicacoes

  • White Papers // Jun 2011

    Estimation of the Feedback Reliability for IB-DFE Receivers

    Single-Carrier (SC) modulation with Frequency-Domain Equalization (FDE) combined with iterative (turbo) FDE schemes has been shown to be suitable for Cyclic-Prefix (CP)-assisted block transmission within broadband wireless systems. Its excellent performance in severely time-dispersive channels makes it a promising candidate for future broadband wireless systems. In this paper, the authors...

    Provided By Instituto de Telecomunicacoes

  • White Papers // Feb 2011

    A Novel Relay Selection Game in Cooperative Wireless Networks Based on Combinatorial Optimization

    Multi-standard mobile devices are allowing users to experience higher data rates and ubiquitous connectivity. These advances are achieved on the expense of higher energy consumption due to the multiple active wireless interfaces. In this paper, the authors use one advantage of the multiple interfaces, namely short range communications. Mobile terminals...

    Provided By Instituto de Telecomunicacoes

  • White Papers // Jul 2010

    C2POWER Approach for Power Saving in Multi-Standard Wireless Devices

    4G networks promise higher data rates and continuous connectivity to multi-standard mobile devices, but at the expense of higher power requirements. Energy is a critical resource for mobile devices, which depend on batteries for power supply. Battery capacity is finite and battery industry is slow, with no promises of any...

    Provided By Instituto de Telecomunicacoes

  • White Papers // Jun 2010

    Converged Wireless Networking and Optimization for Next Generation Services

    The Next Generation Network (NGN) vision is tending towards the convergence of internet and mobile services providing the impetus for new market opportunities in combining the appealing services of internet with the roaming capability of mobile networks. However, this convergence does not go far enough, and with the emergence of...

    Provided By Instituto de Telecomunicacoes

  • White Papers // Nov 2009

    Design and Optimization Next-Generation All-Optical Passive Networks

    This paper describes the progress of the work plan named "Design and Optimization Next Generation Passive All-Optical Networks". The first part of this report focuses on summarizing the status of the activities developed during this academic year. The second part emphasizes the achieved results and lists the conferences and journals...

    Provided By Instituto de Telecomunicacoes

  • White Papers // Oct 2009

    Secure Framework for Voice Transmission Over Multipath Wireless Ad-hoc Network

    With the growth of the Internet services, Voice over IP (VoIP) has been playing a key role in cutting the costs of telephone calls. It can be seen that since the demand of VoIP over wireless network is growing, the use of VoIP over Mobile Ad-hoc NETwork (MANET) is expected...

    Provided By Instituto de Telecomunicacoes

  • White Papers // Mar 2009

    Analysis of Technologies for Long Term Evolution in UMTS

    This paper studies LTE technologies in terms of capacity and coverage. For this purpose, a single user model was developed, estimating the maximum cell radius considering one user performing services. Also, a multiple users and multiple services scenario model was developed, as a more realistic approach. The results from the...

    Provided By Instituto de Telecomunicacoes

  • White Papers // Mar 2009

    Evaluating WiMAX QoS Performance in a Real Testbed

    Broadband Wireless Access technologies are expected to play a central role in next generation networks. WiMAX, based on the IEEE 802.16 standard, has the potential to form the foundation upon which operators will deliver ubiquitous Internet access in the near future. It is also widely anticipated that the next generation...

    Provided By Instituto de Telecomunicacoes

  • White Papers // Mar 2009

    NECO: NEtwork COding Simulator

    It is proved that the max-flow min-cut capacity of a general multicast network can only be achieved by allowing intermediate nodes to mix different data flows, a surge in network coding research has uncovered its potential to provide higher throughput and robustness, particularly where highly volatile networks such as mobile...

    Provided By Instituto de Telecomunicacoes

  • White Papers // Jan 2009

    A Low-Cost Wireless Sensor Network

    This paper presents a Wireless Sensor Network (WSN), which were designed for application in industrial measurements with the use of low-cost commercial components. The concept of the WSN is presented, as well as hot-topics concerning its implementation, in order to make the communication between the nodes and the base-station as...

    Provided By Instituto de Telecomunicacoes

  • White Papers // Jan 2009

    Comparison Between UMTS/HSPA+ and WiMAX/IEEE 802.16e in Mobility Scenarios

    The main purpose of this paper is to compare the performance of UMTS/HSPA+ and mWiMAX. Two scenarios were considered: single and multiple users. The single user model estimates the cell radius for a certain application throughput. Afterwards, the model was adapted to a multiple users and services scenario. The results...

    Provided By Instituto de Telecomunicacoes

  • White Papers // Jan 2009

    Modelling of Linear Coverage in UMTS Applied to Tunnels and Bridges

    This paper addresses the study of coverage, capacity and interference of UMTS in tunnels and bridges. For this purpose, a model accounting for several parameters was developed and implemented in a simulator. The results were compared with measurements performed in the Lisbon Underground and in the 25 de Abril Bridge....

    Provided By Instituto de Telecomunicacoes

  • White Papers // May 2012

    Anomaly Detection Using DSNS and Firefly Harmonic Clustering Algorithm

    The networks are becoming an essential part of society life and anomalies may represent a loss in network performance. Modeling the traffic behavior pattern is possible to predict the behavior expected and characterize an anomaly. The authors proposed a hybrid clustering algorithm, Firefly Harmonic Clustering Algorithm (FHCA), for network volume...

    Provided By Instituto de Telecomunicacoes

  • White Papers // May 2012

    On-Demand Selection, Control and Management of Context-Based Wireless Mesh Networks

    The flexible infrastructure of Wireless Mesh Networks (WMNs) can be exploited to provide support to emerging communication paradigms. In this paper, the authors consider an architecture of context-based virtual WMNs, where the context requirements and preferences of mesh clients are the driving force to dynamically create and configure, through network...

    Provided By Instituto de Telecomunicacoes

  • White Papers // May 2012

    Energy Saving Through Cooperation Using Game Theory-Based Trading Model

    Recent years have witnessed an explosive growth of wireless technologies and applications. The adoption of a wide range of multimedia applications on wireless devices has been made possible through the advances in wireless technologies. Only one aspect is not catching up, which is re-chargeable battery for mobile devices. Without disruptive...

    Provided By Instituto de Telecomunicacoes

  • White Papers // Oct 2009

    Secure Framework for Voice Transmission Over Multipath Wireless Ad-hoc Network

    With the growth of the Internet services, Voice over IP (VoIP) has been playing a key role in cutting the costs of telephone calls. It can be seen that since the demand of VoIP over wireless network is growing, the use of VoIP over Mobile Ad-hoc NETwork (MANET) is expected...

    Provided By Instituto de Telecomunicacoes

  • White Papers // Mar 2009

    NECO: NEtwork COding Simulator

    It is proved that the max-flow min-cut capacity of a general multicast network can only be achieved by allowing intermediate nodes to mix different data flows, a surge in network coding research has uncovered its potential to provide higher throughput and robustness, particularly where highly volatile networks such as mobile...

    Provided By Instituto de Telecomunicacoes

  • White Papers // Mar 2009

    Analysis of Technologies for Long Term Evolution in UMTS

    This paper studies LTE technologies in terms of capacity and coverage. For this purpose, a single user model was developed, estimating the maximum cell radius considering one user performing services. Also, a multiple users and multiple services scenario model was developed, as a more realistic approach. The results from the...

    Provided By Instituto de Telecomunicacoes

  • White Papers // Mar 2009

    Evaluating WiMAX QoS Performance in a Real Testbed

    Broadband Wireless Access technologies are expected to play a central role in next generation networks. WiMAX, based on the IEEE 802.16 standard, has the potential to form the foundation upon which operators will deliver ubiquitous Internet access in the near future. It is also widely anticipated that the next generation...

    Provided By Instituto de Telecomunicacoes

  • White Papers // Jan 2009

    A Low-Cost Wireless Sensor Network

    This paper presents a Wireless Sensor Network (WSN), which were designed for application in industrial measurements with the use of low-cost commercial components. The concept of the WSN is presented, as well as hot-topics concerning its implementation, in order to make the communication between the nodes and the base-station as...

    Provided By Instituto de Telecomunicacoes

  • White Papers // Jan 2009

    Modelling of Linear Coverage in UMTS Applied to Tunnels and Bridges

    This paper addresses the study of coverage, capacity and interference of UMTS in tunnels and bridges. For this purpose, a model accounting for several parameters was developed and implemented in a simulator. The results were compared with measurements performed in the Lisbon Underground and in the 25 de Abril Bridge....

    Provided By Instituto de Telecomunicacoes

  • White Papers // Jan 2009

    Comparison Between UMTS/HSPA+ and WiMAX/IEEE 802.16e in Mobility Scenarios

    The main purpose of this paper is to compare the performance of UMTS/HSPA+ and mWiMAX. Two scenarios were considered: single and multiple users. The single user model estimates the cell radius for a certain application throughput. Afterwards, the model was adapted to a multiple users and services scenario. The results...

    Provided By Instituto de Telecomunicacoes

  • White Papers // Nov 2009

    Design and Optimization Next-Generation All-Optical Passive Networks

    This paper describes the progress of the work plan named "Design and Optimization Next Generation Passive All-Optical Networks". The first part of this report focuses on summarizing the status of the activities developed during this academic year. The second part emphasizes the achieved results and lists the conferences and journals...

    Provided By Instituto de Telecomunicacoes

  • White Papers // Jun 2010

    Converged Wireless Networking and Optimization for Next Generation Services

    The Next Generation Network (NGN) vision is tending towards the convergence of internet and mobile services providing the impetus for new market opportunities in combining the appealing services of internet with the roaming capability of mobile networks. However, this convergence does not go far enough, and with the emergence of...

    Provided By Instituto de Telecomunicacoes

  • White Papers // Jun 2011

    Estimation of the Feedback Reliability for IB-DFE Receivers

    Single-Carrier (SC) modulation with Frequency-Domain Equalization (FDE) combined with iterative (turbo) FDE schemes has been shown to be suitable for Cyclic-Prefix (CP)-assisted block transmission within broadband wireless systems. Its excellent performance in severely time-dispersive channels makes it a promising candidate for future broadband wireless systems. In this paper, the authors...

    Provided By Instituto de Telecomunicacoes

  • White Papers // Sep 2011

    FEBER: Feedback Based Erasure Recovery for Real-Time Multicast Over 802.11 Networks

    The authors consider the problem of broadcasting data streams over a wireless network for multiple receivers with reliability and timely delivery guarantees. In their framework, they consider packets that need to be delivered within a given time interval, after which the packet is no longer useful at the application layer....

    Provided By Instituto de Telecomunicacoes

  • White Papers // Feb 2011

    A Novel Relay Selection Game in Cooperative Wireless Networks Based on Combinatorial Optimization

    Multi-standard mobile devices are allowing users to experience higher data rates and ubiquitous connectivity. These advances are achieved on the expense of higher energy consumption due to the multiple active wireless interfaces. In this paper, the authors use one advantage of the multiple interfaces, namely short range communications. Mobile terminals...

    Provided By Instituto de Telecomunicacoes

  • White Papers // Jul 2010

    C2POWER Approach for Power Saving in Multi-Standard Wireless Devices

    4G networks promise higher data rates and continuous connectivity to multi-standard mobile devices, but at the expense of higher power requirements. Energy is a critical resource for mobile devices, which depend on batteries for power supply. Battery capacity is finite and battery industry is slow, with no promises of any...

    Provided By Instituto de Telecomunicacoes

  • White Papers // Jan 2012

    Iterative Decoding and Channel Estimation of MIMO-OFDM Transmissions With Hierarchical Constellations and Implict Pilots

    It is widely recognized that OFDM modulations (Orthogonal Frequency Division Multiplexing) are suitable for broadband wireless systems. For this reason they were selected for several digital broadcast systems and wireless networks and are being considered for UTRA (Universal Mobile Telecommunications System Terrestrial Radio Access) Long-Term Evolution (LTE). Regarding LTE UTRA,...

    Provided By Instituto de Telecomunicacoes