Search results for "Communications system"
showing 8 items of 78 documents
Energy Efficient Optimization for Solar-Powered UAV Communications System
2021
In this work, we explore the energy efficiency optimization for a solar-powered unmanned aerial vehicle (UAV) communications system. We consider a scenario where a number of ground users (GUs) connect with a solar-powered multi-antenna UAV over a wireless link. First, we are able to derive the relations between the uplink data rate and heading angle of UAV and transmission power of GUs. In addition, the harvested energy from solar light is also affected by UAV’s angle. Accordingly, with the objective to maximize the energy efficiency that is related to uplink data rate and energy consumption, we propose to dynamically adjust the UAV trajectory and gesture, by optimizing its velocity, accele…
Trust-based framework for security enhancement of P2PSIP communication systems
2009
Today, Peer-to-Peer SIP based communication systems have attracted much attention from both academia and industry. The decentralized nature of P2P might provide the distributed peer-to-peer communication system without help of the traditional SIP server. However, it comes to the cost of reduced trustworthiness and may cause security problems, e.g. privacy leaks, unpredictable availability, etc. In this paper, we investigate on P2PSIP security issues and propose a subjective based trust model that offers trust services during P2PSIP session establishment. The main issues considered in this model include opinion calculation, opinion maintenance, data confidentiality and integrity, message rou…
Service Provisioning and User Association for Heterogeneous Wireless Railway Networks
2017
In addition to comforting passengers' journey, the modern railway system is responsible to support a variety of on-board Internet services to meet the passenger's demands on seamless service provisioning. In order to provide wireless access to the train, one idea attracting increasing attention is to deploy a series of track-side access points (TAPs) with high-speed data rates along the rail lines dedicated to the broadband mobile service provisioning on board. Due to the heavy data traffic flushing into the base stations (BSs) of the cellular networks, TAPs act as a complement to the BSs in data delivery. In this paper, we focus on the TAP association problem for service provisioning in a …
Model of line to shield power line communication system on a Medium Voltage network
2010
In this paper a complete model of a power line communication (PLC) system on a Medium Voltage (MV) network is presented in the case of a line-ground configuration. A simple and friendly Simulink (R) software is used to develop the model. A distributed parameter MV cable model in line-ground configuration is considered together with the power transformers, the signal coupling networks and the receiving and transmitting line coupling interface of a ST7540 FSK powerline transceiver. The performances of the complete PLC communication system are evaluated for different line lengths by means of the attenuation computed as ratio between the received and transmitted voltage signals.
Simulation of a Power Line Communication System in Medium and Low Voltage Distribution Networks
2011
The aim of the paper is to study the influence of the power transformer on signal transmission in the case of a power line communication (PLC) system in a overhead Medium Voltage (MV) power network. A model of the PLC system was carried out by means of the Simulink® software. A distributed parameter MV overhead line, two power transformers, the signal coupling networks and the receiving and transmitting line coupling interface of a ST7540 FSK powerline transceiver were included in the model. The performances of the complete PLC communication system are evaluated for different line lengths by means of the attenuation computed as ratio between the received and transmitted voltage signals.
Measurement and communication interfaces for distributed generation in smart grids
2013
The aim of this work is to perform a feasibility study on the measurement and communication strategies for the development of a new generation of interface devices for distributed generators and their integration on smart grids. The communication system can use one or more technologies, at the various levels, creating a low cost network infrastructure, in the framework of a SCADA (Supervisory Control and Data Acquisition) architecture. As regards the measurements, the attention is focused on the anti-islanding protection, based on a hybrid solution, which makes use of local measurements and communications with the grid, at both MV and LV level by employing the PLC technology. Some simulatio…
Multi-hop D2D Communications with Network Coding : From A Performance Perspective
2019
Multi-hop device-to-device (D2D) communications play an important role in expanding D2D coverage. In this paper, we study a relay-based and network-coding-assisted (in particular, XOR coding) multi-hop D2D communication system. In the system, toward jointly considering the impact of interference and network traffic conditions on the quality of D2D communications, various channel fading models and traffic models are investigated, and the packet loss probability of D2D links is meticulously computed using these models. With the packet loss probability of D2D links, the general closed-form expressions of end-to-end packet loss probability (E2EPLP) of the system with the presence (or absence) o…