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Graphical abstract, Point to point communication in free-space is severely dependent upon the alignment of the transmitter and receiver devices. The simplest low cost method for the alignment is achieved by utilising two geographical coordinates and an electronic compass. However, some regions of the Earth have a strong magnetic deviation that can introduce large errors to such systems. Other known methods, that can be utilised are a radio direction finder or stars sensor however these methods are too expensive. Here, we present a system which uses three GPS coordinates for the alignment of the transmitter and the receiver, of which two coordinates are measured on the transmitter side, while the receiver is previously known. The transmitter side positions can be relocated for convenience. The methods were tested using Google™ Maps for a long distance within the northern and southern hemisphere, while the experiment was performed for a short distance within the southern hemisphere. The system was developed based on the following considerations: • Algorithm Implementable into a Micro-Controller Unit (MCU) or a standard computer. • The local magnetic deviation does not have any influence on the method. • Can be use where the internet connection is not available, such as mountains and others remote areas.

The research process was based on the design of a desktop application for indoor and outdoor coverage testing of wireless links in the 2.4 GHz frequency band with the use of free software, which allows capturing, processing, analysing, calculate and generate a real-time statistical type mathematical model of the media access control (MAC) hardware embedded in a laptop's wireless network card that detects power level, carriers, and other variables within frames of information transmitted by base stations. The methodology is experimental. First, different propagation models are analysed, next existing test tools are studied, and then hardware and software technologies and tools are compared. The programming language is selected and finally the code and the graphical interface of the application are generated in order to visualize the mathematical model expressed through the use of least squares with the Leven-berg-Marquardt algorithm and then compare it with recognized propagation models. RESUMEN El proceso de investigación se basó en el diseño de una aplicación de escritorio para pruebas de cobertura en interiores y exteriores de enlaces inalámbricos en la banda de frecuencias de 2,4 GHz con el uso de software libre, que permite capturar, procesar, analizar, calcular y generar un modelo matemático de tipo estadístico en tiempo real, del hardware del control de acceso al medio (MAC) incorporado en la tarjeta de red inalámbrica de una computadora portátil que detecta el nivel de potencia, las portadoras y otras variables dentro de los tramas de información que transmiten las estaciones base. La metodología es experimental. Primero, se analizan diferentes modelos de propagación, luego se estudian las herramientas de prueba existentes y luego se comparan las tecnologías y herramientas de hardware y software; se selecciona el lenguaje de programación y finalmente se genera el código y la interfaz gráfica de la aplicación con el fin de visualizar el modelo matemático expresado mediante el uso de mínimos cuadrados con el algoritmo de Levenberg-Marquardt y compararlo con modelos de propagación reconocidos. RESUMO O processo de investigação está baseado no desenho de um aplicativo desktop para provas de cobertura em interiores e exteriores de enlaces sem fio na banda de frequências de 2,4 GHz com o uso de software livre, que permite capturar, processar, analisar, calcular e gerar um modelo matemático de tipo estatístico em tempo real do hardware do controle de acesso à mídia (MAC) incorporado na placa de rede sem fio de um computador portátil - laptop- que detecta o nível de potência, as portadoras e outras variáveis dentro dos tramas de informação que transmitem as estações base. A metodologia é experimental. Primeiro, são analisados diferentes modelos de propagação, depois, são estudadas as ferramentas de prova existentes e depois se comparam as tecnologias e ferramentas de hardware e software; se seleciona a linguagem de programação e finalmente gera-se o código e a interfase gráfica do aplicativo com a finalidade de visualizar o modelo matemático expressado por meio do uso de mínimos quadrados com o algoritmo de Levenberg-Marquardt e compará-lo com modelos de propagação reconhecidos.

International audience; A superheterodyne transmission scheme is adopted and analyzed in a 300 GHz wireless point-to-point link. This was realized using two different intermediate frequency (IF) systems. The first uses fast digital synthesis which provides an IF signal centered around a carrier frequency of 10 GHz. The second involves the usage of commercially available mixers, which work as direct up- and down-converters, to generate the IF input and output. The radio frequency components are based on millimeterwave monolithic integrated circuits at a center frequency of 300 GHz. Transmission experiments over distances up to 10 m are carried out. Data rates of up to 60 Gbps using the first IF option and up to 24 Gbps using the second IF option are achieved. Modulation formats up to 32QAM are successfully transmitted. The linearity of this link and of its components is analyzed in detail. Two local oscillators (LOs), a photonics-based source and a commercially available electronic source are employed and compared. This work validates the concept of superheterodyne architecture for integration in a beyond-5G network, supplying important guidelines that have to be taken into account in the design steps of a future wireless system.

Renatech Network; International audience; In this article, we present a 300-GHz wireless link composed of a photonic uni-traveling-carrier diode transmitter and an active electronic receiver based on millimeter wave integrated circuits fabricated in an InGaAs metamorphic high electron mobility transistor technology. The input pseudorandom binary sequence is transmitted and analyzed offline using fast analog-to-digital converters. The data transmission reaches ,100 Gb/s over a distance of 15 m. Complex modulation formats, such as 32-quadrature amplitude modulation and 64-quadrature amplitude modulation, are successfully transmitted up to a symbol rate of 8 GBd. The system presents not only high linearity but is also capable of transmitting high symbol rates, up to 40 GBd. To the best of the authors' knowledge, this represents the highest ever reported transmission bandwidth as well as the highest spectral density symbol rate product for transmissions with center frequency in the terahertz band. Thus, the usage of such links in future bandwidth-hungry applications, such as data centers, data showers, fronthaul, and backhaul, is proven feasible.

This paper presents a study of the D-band radio solutions, with beam-steering functionality, intended for use in the reconfigurable meshed networks. The regulation and radio network constraints defining the specifications of a D-band transceiver are reviewed. The architecture of the radio link is proposed and key enabling technologies needed to build the D-band transceiver with beam-steering functionality are presented.

In recent years, interferometric radars have been extensively used as sensors for static and dynamic monitoring of bridges. Generally speaking, a radar can only detect the displacement component along its view direction. As the movement of a real bridge or a large structure can be rather complex, this limitation can be a significant drawback in engineering practice. In order toovercome this limitation, in this article, a multi-monostatic interferometric radar with radio link is proposed. This radar is able to detect a second component of displacement using a transponder. The transponder is connected to the radar through a radio link. The radio link allows the installation of the transponder far away from the radar, and even in the opposite direction. The equipment is based on a MIMO radar, two transceivers for the radio link, and a transponder. The transceivers and the transponder are essentially two antennas and an amplifier system. The equipment is experimentally tested in controlled scenarios and in the case study of Indiano Bridge, Florence, Italy.

This paper presents a study of the D-band radio solutions, with beam-steering functionality, intended for use in the reconfigurable meshed network. The regulation and radio network constraints defining the specifications of a D-Band transceiver are reviewed. The architecture of the radio link is proposed and key enabling technologies needed to build the D-band transceiver are presented. The proposed solutions can be used for plenty of different radio connections, since they can provide a capacity level up to 100 Gbps over 160 meter and, at reduced capacity, hop lengths exceeding 1 km.

The European Train Control System (ETCS) is the leading signaling system for train command and control. In the future, ETCS may be delivered over long-term evolution (LTE) networks. Thus, LTE performance offered to ETCS must be analyzed and confronted with the railway safety requirements. It is especially important to ensure the integrity of the ETCS data, i.e., to protect ETCS data against loss and corruption. In this article, various retransmission mechanisms are considered for providing end-to-end ETCS data integrity in LTE. These mechanisms are validated in simulations, which model worst-case conditions regarding train locations, traffic load, and base-station density. The simulation results show that ETCS data integrity requirements can be fulfilled even under these unfavorable conditions with the proper LTE mechanisms.

International audience; Industrial applications require more and more low-power operations, low-delay, deterministic communications as well as end-to-end reliability close to 100%. IEEE 802.15.4-TSCH (Time-Slotted Channel Hopping) relies on a channel hopping technique while scheduling properly the transmissions to provide a high end-to-end reliability. Because of external interference, some channels may perform very poorly locally, which impacts negatively the reliability for some radio links. We propose here the first distributed scheduling solution which reactively allocates the cells to each pair of nodes while also considering local blacklists. These local blacklists are constructed on a per-radio link basis to reflect the actual performance encountered locally. Our simulations highlight the relevance of our distributed blacklisting aware scheduling algorithm to improve both the reliability and the delay efficiency compared with DeTAS, a state of the art distributed solution.

A new application of utilizing ultra-wideband (UWB) technology to sense wind turbine blade deflections is introduced in this paper for wind energy cost reduction. The lower UWB band of 3.1–5.3 GHz is applied. On each blade, there will be one UWB blade deflection sensing system, which consists of two UWB antennas at the blade root and one UWB antenna at the blade tip. The detailed topology and challenges of this deflection sensing system are addressed. Due to the complexity of the problem, this paper will first realize the on-blade UWB radio link in the simplest case, where the tip antenna is situated outside (and on the surface of) a blade tip. To investigate this case, full-blade time-domain measurements are designed and conducted under different deflections. The detailed measurement setups and results are provided. If the root and tip antenna locations are properly selected, the first pulse is always of sufficient quality for accurate estimations under different deflections. The measured results reveal that the blade tip-root distance and blade deflection can be accurately estimated in the complicated and lossy wireless channels around a wind turbine blade. Some future research topics on this application are listed finally.

The weather s impact on the performance of a radio link at the 2.4 GHz ISM (Industry, Scientific and Medical) band had not been yet studied in great detail up to now as it is generally believed that the ultra-high frequency band is not significantly affected by weather conditions. However, our study shows significant correlations between meteorological variables and control frame errors at MAC (Medium Access Control) layer of the IEEE 802.11b/g standard. This study is performed over an outdoor radio link setting which has been monitored for several months. Moreover, we check if link distance and so modulation scheme and data rate are also decisive features of such impact. Our real scenario is composed of a point-to-multipoint link, one longer distance s than the other one. Finally, we conclude that the weather impacts on the number of control frame errors, and so it should be taken into account to design and deploy outdoor radio links IEEE 802.11b/g. Moreover, we have showed that such impact depends on data rate and modulation scheme., This work has been supported in part by the Vicerrectorado de Investigacion, Innovacion y Transferencia of the Universitat Politecnica de Valencia (UPV) through the Programa de Movilidad e Internalizacion Academica (PMIA-2013) thanks the Programa Campus de Excelencia Internacional (VLC/CAMPUS) funded by the Ministerio de Educacion, Cultura y Deporte of Spain, and by the same Vicerrectorado through the Programa para la Formacion de Personal Investigador (FPI) subprograma 1. The authors would like to thank the Information and Communications Systems Office (ASIC) of the UPV for supporting the setting of this work, Borja Opticos Enterprise for providing meteorological data and Azimut Electronics Company for allowing us to use its head office as a point link.

Two-year experimental research results of radio signal propagation and fading are presented in this paper. Microwave wireless links located in coastal and continental terrain and operated at 15 GHz were tested. The impacts of different atmosphere phenomena such as rain, brume, dew, weather, ground and dew point temperatures on the signal strength fading in these wireless links were assessed. Additionally, multipath effect origin and rain attenuation were analysed. DOI: http://dx.doi.org/10.5755/j01.eee.20.4.2921

Wireless Sensor Networks in volatile environments may suffer damage, and connectivity must be restored. The repairing agent must discover surviving nodes and damage to the physical and radio environment as it moves around the sensor field to execute the repair. We compare two approaches, one which re-generates a full plan whenever it discovers new knowledge, and a second which attempts to minimise the required number of new radio nodes. We apply each approach with two different heuristics, one which attempts to minimise the cost of new radio nodes, and one which aims to minimise the travel distance. We conduct extensive simulation-based experiments, varying key parameters, including the level of damage suffered, and comparing directly with the published state-of-the-art. We quantify the relative performance of the different algorithms in achieving their objectives, and also measure the execution times to assess the impact on being able to make autonomous decisions in reasonable time.

To increase cognitive radio operation efficiency, this paper proposes a new knowledge management functional architecture, based on the fittingness factor concept, for supporting spectrum management in non-stationary environments. It includes a reliability tester module that detects, based on hypothesis testing, relevant changes in suitability levels of spectrum resources to support a set of heterogeneous applications. These changes are captured through a set of advanced statistics stored in a knowledge database and exploited by a proactive spectrum management strategy to assist both spectrum selection and spectrum mobility functionalities. The results reveal that the proposed reliability tester is able to disregard the changes due to the intrinsic randomness of the radio environment and to efficiently detect actual changes in interference conditions of spectrum pools. Thanks to this support, the proposed spectrum management strategy exhibits substantial robustness when the environment becomes non-stationary, obtaining performance improvements of up to 75% with respect to the reference case that does not make use of the reliability tester functionality.

Mobile wireless sensors in indoor environments will experience multipath fading, causing rapid variations in the capacity of the radio link. We present a strategy that increases the throughput by modifying the trajectory of the sensor so it spends more time at positions where the capacity is high. While doing so, it still maintains some desired average velocity. Our approach includes closed-loop estimation of the parameters of the fading, which may change when moving between rooms. We prove stability of the feedback system and illustrate its behavior through simulations. Finally, we demonstrate robustness to errors in the channel model. © 2010 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.QC 20101223

This paper presents the PhD work conducted by Na TAO. The director of this thesis is Professor Michel BOUSQUET. The study is supervised by Alain PIROVANO and Jose RADZIK. This PhD work has started January 2006 and will end in December 2008. Two concurrent satellite systems are presently proposed for in-flight entertainment (IFE) communications, thus demonstrating the capability of satellites to provide multimedia access to users on board airplanes. At the same time, an increasing interest for the use of satellite communications for air traffic control has been motivated by the increasing load of traditional radio links, mainly in the VHF band. However, the development of a dedicated satellite system for ATC (Air Traffic Control) and ATN (Aeronautical Telecommunication Network) seems to be a long-term perspective. The objective of the presented system design is to provide both passenger application traffic (Internet, GSM) access and a high-reliability channel for aeronautical applications using the same satellite links. Due to the constraints in capacity and radio bandwidth allocation, very high frequencies (above 20 GHz) are considered here. The corresponding design implications for the air interface are taken into account and access performances are derived using a dedicated simulation model. Some preliminary results are shown in this paper to demonstrate the technical feasibility of such system design with increased capacity, more details and the open issues will be studied in the future of the thesis research.

Agriculture accounts for a significant portion of the GDP in most developed countries. However, managing farms, particularly large-scale extensive farming systems, is hindered by lack of data and increasing shortage of labour. We have deployed a large heterogeneous sensor network on a working farm to explore sensor network applications that can address some of the issues identified above. Our network is solar powered and has been running for over 6 months. The current deployment consists of over 40 moisture sensors that provide soil moisture profiles at varying depths, weight sensors to compute the amount of food and water consumed by animals, electronic tag readers, up to 40 sensors that can be used to track animal movement (consisting of GPS, compass and accelerometers), and 20 sensor/actuators that can be used to apply different stimuli (audio, vibration and mild electric shock) to the animal. The static part of the network is designed for 24/7 operation and is linked to the Internet via a dedicated high-gain radio link, also solar powered. The initial goals of the deployment are to provide a testbed for sensor network research in programmability and data handling while also being a vital tool for scientists to study animal behavior. Our longer term aim is to create a management system that completely transforms the way farms are managed.

Link layer error control is widely adopted in wireless LANs (WLANs) to hide the unreliability of the wireless channel to higher level protocols. This allows classic end-to-end congestion control algorithms to achieve acceptable throughput even in the presence of radio links. The present work investigates the performance of Westwood+ and NewReno TCP over a noisy wireless LAN channel. In particular, the effect of local error control persistency on the end-to-end performances of Westwood+ and NewReno TCP is addressed. The investigation has been carried out by using ns-2 computer simulation. Simulation results show that (1) in the presence of uniformly distributed packet losses a well tuned local error control leads both Westwood+ and NewReno TCP to full network utilization; (2) in the presence of bursty losses Westwood+ TCP improves the good-put with respect to NewReno TCP also in the presence of local error control; in particular, Westwood+ TCP requires a smaller number of retransmissions at the link layer than New Reno to achieve full utilization of the wireless channel.

Heterogeneous communication networks with their variety of application demands, uncertain time-varying traffic load, and mixture of wired and wireless links pose several challenging problem in modeling and control. In this paper we focus on the packet delay, which is an important variable for efficient end-to-end congestion control. In particular, we study the delay effects of radio links which use power control and link-layer retransmissions. Link-layer retransmissions induce delays which do not conform to the assumptions on which the transport protocol is based. This causes undesired TCP control actions which reduce throughput. A link-layer solution based on adding carefully selected delays to certain packets is proposed to counteract this problem. All information needed for this is available locally at the link. © 2004 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.QC 20120220

The importance of air transportation in everyday's life has increased dramatically, in the last few years. Among the consequences of the growing demand for air-related services, the need of assuring an exact and timely flight arrival has become a crucial factor, both for safety and economical reasons. At the same time, broadcasting antennas, radio links and cellular telephone base stations demand continuously increasing spaces around airports, representing a source of disturbing interference for radio-navigation systems. An improved instrumental landing system (ILS) receiver based on array processing concepts is proposed for safer automatic landing procedures. The new approach is based on direction of arrival (DOA) estimation performed by the UN-MUSIC algorithm. The superior performance of the proposed system with respect to currently employed techniques in the presence of unwanted interferences has been tested in extensive computer simulations.