Search results for "working"
showing 10 items of 2747 documents
Analysis of the Non-Transparent In-Band Relays in the IEEE 802.16 Multi-Hop System
2010
This paper presents extensive dynamic simulations of the non-transparent in-band relays working in the distributed scheduling mode. The simulation results show that in-band relays can improve noticeably the spectral efficiency without acquiring an additional radio spectrum. Also, packet transmission delays become smaller. An important outcome of the dynamic simulations is that it is very crucial to choose a correct relay zone size where the base station and relay nodes exchange data. Otherwise, throughput fairness of the whole system declines. It indicates an importance of the relay zone size adjustment algorithm that the base station must run.
Enabling a win-win coexistence mechanism for WiFi and LTE in unlicensed bands
2018
The problem of WiFi and LTE coexistence has been significantly debated in the last years, with the emergence of LTE extensions enabling the utilization of unlicensed spectrum for carrier aggregation. Since the two technologies employ com-pletely different access protocols and frame transmission times, supporting coexistence with minimal modifications on existing protocols is not an easy task. Current solutions are often based on LTE unilateral adaptations, being LTE in unlicensed bands still under definition. In this paper, we demonstrate that it is possible to avoid a subordinated role for WiFi nodes, by simply equipping WiFi nodes with a sensing mechanism based on adaptive tunings of the …
Capacity and Energy-Consumption Optimization for the Cluster-Tree Topology in IEEE 802.15.4
2011
International audience; 802.15.4 proposes to use a cluster-tree hierar- chy to organize the transmissions in Wireless Sensor Networks. In this letter, we propose a framework to analyze formally the capacity and the energy consumption of this structure. We derive a Mixed Integer Linear Programming (MILP) formulation to obtain a topology compliant with the standard. This formulation provides the optimal solution for the network capacity: this con- stitutes an upper bound for any distributed algorithms permitting to construct a cluster-tree. This framework can also be used to evaluate the capacity and to compare quantitatively different cluster-tree algorithms.
On-body and off-body transmit power control in IEEE 802.15.6 scheduled access networks
2014
Wireless Body Area Networks (WBANs) have received much attention due to the possibility to be used in healthcare applications. For these applications, energy saving is a critical issue, as in many cases, batteries cannot be easily replaced. A transmit power control scheme, able to adapt to the variations of the wireless body channel, will allow consistent energy saving and longer battery life. In this paper we propose a transmit power control scheme suitable for IEEE 802.15.6 narrowband scheduled access networks, in which the transmission power is modulated frame by frame according to a run-time estimation of the channel propagation conditions. A simple and effective line search algorithm i…
Statistical learning and multiple linear regression model for network selection using MIH
2014
Award of Appreciation; International audience; A key requirement to provide seamless mobility and guaranteeing Quality of Service in heterogeneous environment is to select the best destination network during handover. In this paper, we propose a new schema for network selection based on Multiple Linear Regression Model (MLRM). A horough investigation, on a huge live data collected from GPRS/UMTS networks led to identify the Key Performance Indicators (KPIs) that play the most important role in the handover process. These KPIs are: Received Signal Code Power (RSCP), received energy per chip (Ec/No) and Available Bandwidth (ABW) of the destination network. To extract a handover model from col…
Modelling of Mobile-To-Mobile MIMO Channels
2007
Masteroppgave i informasjons- og kommunikasjonsteknologi 2007 – Høgskolen i Agder, Grimstad Mobile-to-Mobile (M2M) communications are expected to play are expected to play an important role in various elds including ad hoc networks and intelligent transportation systems. In such systems, extremely reliable links are required. To cope with problems faced during the development and performance investigation of futureMobile-to-Mobile multi-input multi-output (MIMO) communication systems, a solid knowledge of the underlying multipath fading channel characteristics is essential. This master thesis focuses on the modelling, analysis, and simulation of M2M single-input single-output (SISO) and M2M…
Tarifas Portuárias: Um Estudo Comparativo entre os Sistemas Portuário Brasileiro e Espanhol
2014
The objective of this study is to investigate and document the system of port taxes in Brazil and Spain. To achieve this, we consulted the laws, rules and documents, and the websites of the main Brazilian and Spanish ports. The study is unprecedented and brings out a little researched topic in Brazil, which is the port taxes. The results show that the Spanish system is structured by defining the different types of taxes to be charges. While the tax for Brazilian ports is confusing to present a diversity of shapes and charging models. This study has practical implications as they search alercar and present a system that can serve as a model for Brazil. This is because the port rates have a d…
Pattern Identification by Factor Analysis for Regions with Similar Economic Activity Based on Mobile Communication Data
2018
The study analyses the regions’ economic activity in Latvia using Latvia Mobile Telephone (LMT) mobile communication data from July 2015 to January 2017. The call activity and a number of unique phone users by 119 Latvia counties and biggest cities were analysed in two steps: at first method of principal components was used to explain the variance in the data and then exploratory factor analysis was applied. Three factors were identified that describe 87.5% of the total variance of the aggregated daily data. The first factor is related more to the regions with higher economic activity, the second and third factors capture, respectively, lowers call activity during weekdays and are related t…
A Stigmergic Guiding System to Facilitate the Group Decision Process
2012
The paper presents a stigmergic approach to engineer a guiding system to facilitate the complex problem of designing the group decision processes. The system aims to provide contextual, actionable recommendations based on the knowledge and past experience of its users as recorded in a collaborative working environment implemented around the concept of stigmergic systems. Through an agent-based socio-simulation experiment we have demonstrated already the feasibility of this approach. The paper illustrates how the simulation results are transferred into a guiding system that facilitates the group decision process design through iterative queries reformulations for the identification, represen…
Experimental realization of a Persistent Identifier Infrastructure stack for Named Data Networking
2015
The continuation of Persistent Identifier Infrastructures is crucial when next-generation Internet architectures based on Information-Centric Networking (ICN) arise. When moving to ICN, we must ensure the resolution of Persistent Identifiers (PID), such as the billions of Digital Object Identifiers (DOI) used today, to provide continued access to scientific literature and research data. It provides the base for the necessary transformations in the Handle System architecture and protocol for running a PID system on the Named Data Networking (NDN) architecture, which is a recent incarnation of ICN. Furthermore, it examines the PID-specific resolution access patterns, investigates the expected…