Smooth Three-Dimensional Route Planning for Fixed-Wing Unmanned Aerial Vehicles With Double Continuous Curvature

This paper presents a smooth flight path planner for maneuvering in a 3D Euclidean space, which is based on two new space curves. The first one is called 'Elementary Clothoid-based 3D Curve (ECb3D)', which is built by concatenating two symmetric Clothoid-based 3D Curves (Cb3D). The combination of these curves allows to reach an arbitrary orientation in 3D Euclidean space. This new curve allows to generate continuous curvature and torsion profiles that start and finish with a null value, which means that they can be concatenated with other curves, such as straight segments, without generating discontinuities on those variables. The second curve is called 'Double Continuous Curvature 3D Curve (DCC3D)' which is built as a concatenation of three straight line segments and two ECb3D curves, allowing to reach an arbitrary configuration in position and orientation in the 3D Euclidean space without discontinuities in curvature and torsion. This trajectory is applied for autonomous path planning and navigation of unmanned aerial vehicles (UAVs) such as fixed-wing aircrafts. Finally, the results are validated on the FlightGear 2018 flight simulator with the UAV kadett 2400 platform

Experimental characterization and mitigation of turbulence induced signal fades within an ad hoc FSO network

Optical beams propagating through the turbulent atmospheric channel suffer from both the attenuation and phase distortion. Since future wireless networks are envisaged to be deployed in the ad hoc mesh topology, this paper presents the experimental laboratory characterization of mitigation of turbulence induced signal fades for two ad hoc scenarios. Results from measurements of the thermal structure constant along the propagation channels, changes of the coherence lengths for different turbulence regimes and the eye diagrams for partially correlated turbulences in free space optical channels are discussed. Based on these results future deployment of optical ad hoc networks can be more straightforwardly planned

Application of Radio environment map reconstruction techniques to platoon-based cellular V2X communications

Vehicle platoons involve groups of vehicles travelling together at a constant inter-vehicle distance, with different common benefits such as increasing road efficiency and fuel saving. Vehicle platooning requires highly reliable wireless communications to keep the group structure and carry out coordinated maneuvers in a safe manner. Focusing on infrastructure-assisted cellular vehicle to anything (V2X) communications, the amount of control information to be exchanged between each platoon vehicle and the base station is a critical factor affecting the communication latency. This paper exploits the particular structure and characteristics of platooning to decrease the control information exchange necessary for the channel acquisition stage. More precisely, a scheme based on radio environment map (REM) reconstruction is proposed, where geo-localized received power values are available at only a subset of platoon vehicles, while large-scale channel parameters estimates for the rest of platoon members are provided through the application of spatial Ordinary Kriging (OK) interpolation. Distinctive features of the vehicle platooning use case are explored, such as the optimal patterns of vehicles within the platoon with available REM values for improving the quality of the reconstruction, the need for an accurate semivariogram modeling in OK, or the communication cost when establishing a centralized or a distributed architecture for achieving REM reconstruction. The evaluation results show that OK is able to reconstruct the REM in the platoon with acceptable mean squared estimation error, while reducing the control information for REM acquisition in up to 64% in the best-case scenario

Multicore Fiber Opportunities for Centralized Radio Access Networks

Les arquitectures de ràdio sobre fibra concebudes per a la propera generació de sistemes d’accés sense fils es basen en xarxes d’accés a ràdio centralitzades (C-RAN), on els recursos de processament de banda base corresponents a diferents estacions base remotes (BS) s’allotgen en una oficina central compartida (CO). Proposem l'explotació de les característiques úniques que aporta el paral·lelisme inherent de les fibres de diversos nuclis com a solució compacta per implementar la connectivitat CO-BS necessària en C-RAN.JCI-2012-14805PROMETEO II/2013/012Radio-over-fiber architectures conceived for the next generation of wireless access systems are based on Centralized Radio Access Networks (C-RAN), where the baseband processing resources corresponding to different remote base stations (BS) are hosted in a shared central office (CO). We propose the exploitation of the unique features brought by the inherent parallelism of multicore fibers as a compact solution to implement the required CO-BS connectivity in C-RANs

On the use of composite indicators for mobile communications network management in smart sustainable cities

Beyond 5G networks will be fundamental towards enabling sustainable mobile communication networks. One of the most challenging scenarios will be met in ultra-dense networks that are deployed in densely populated areas. In this particular case, mobile network operators should benefit from new assessment metrics and data science tools to ensure an effective management of their networks. In fact, incorporating architectures allowing a cognitive network management framework could simplify processes and enhance the network's performance. In this paper, we propose the use of composite indicators based on key performance indicators both as a tool for a cognitive management of mobile communications networks, as well as a metric which could successfully integrate more advanced user-centric measurements. Composite indicators can successfully synthesize and integrate large amounts of data, incorporating in a single index different metrics selected as triggers for autonomous decisions. The paper motivates and describes the use of this methodology, which is applied successfully in other areas with the aim of ranking metrics to simplify complex realities. A use case that is based on a universal mobile telecommunications system network is analyzed, due to technology simplicity and scalability, as well as the availability of key performance indicators. The use case focuses on analyzing the fairness of a network over different coverage areas as a fundamental metric in the operation and management of the networks. To this end, several ranking and visualization strategies are presented, providing examples of how to extract insights from the proposed composite indicator

Polarization Division Multiplexing of OFDM Radio-over-Fiber Signals in Passive Optical Networks

These PDF files is subject to reprint fees[EN] This paper describes the state-of-the-art of polarization multiplexing for optical networks transmission. The use of polarization division multiplexing (PDM) permits to multiply the user capacity and increase the spectral efficiency. Combining PDM and orthogonal frequency division multiplexed (OFDM) modulation allows maximizing the optical transmission capacity. The experimental demonstration of transmitting OFDM signals following ECMA-368 ultrawide band (UWB) standard in radio-over-fiber using PDM in passive optical networks is herein reported. The impact of cross-polarization and cochannel crosstalk is evaluated experimentally in a three-user OFDM-UWB subcarrier multiplexed (SCM) configuration per polarization. Each SCM uses up to three OFDM-UWB channels of 200 Mbit/s each, achieving an aggregated bitrate of 1.2 Gbit/s with 0.76 bit/s/Hz spectral efficiency when using PDM transmission. The experimental results for the polarization-multiplexed SCM indicate that a 4 dB additional polarization crosstalk interference can be expected compared to a nonpolarization-multiplexed transmission system which translates to 2.4 dB EVM penalty in the UWB signals. The successful PDM transmission of SCM multiuser OFDM-UWB over a passive optical network of 25 km standard-single mode fiber (SSMF) reach is demonstrated.This work has been supported by Spain National Plan Project MODAL “Few-mode propagation technology in single mode fibre” (TEC2012-38558-C02-01). UPV Project MUMOX “Optical modal multiplexing for high-performance network interconnection” (PAID-05-12 SP20120821) is also acknowledged. M. Morant’s work is supported by Generalitat Valenciana VALi+D Postdoc Program. J. Perez’s work is supported by Spanish MINECO Juan de la Cierva Fellowship JCI-2012-14805.Morant Pérez, M.; Pérez Soler, J.; Llorente Sáez, R. (2014). Polarization Division Multiplexing of OFDM Radio-over-Fiber Signals in Passive Optical Networks. Advances in Optical Technologies. 2014(1):1-9. https://doi.org/10.1155/2014/269524S192014

Wireless energy and information transmission in FSO and RF-FSO links

We propose and analyze a wireless energy and information transmission scheme in free-space optical (FSO) links. The results are presented for both quasi-static and fast-fading conditions. We derive closed-form expressions for throughput, outage probability, and optimal power allocation optimizing the system throughput/outage probability. Finally, we complement the FSO link with an additional radio frequency (RF) link to create a hybrid RF-FSO system and reduce the system outage probability. The results show that joint implementation of the RF and FSO links leads to considerable performance improvement, compared to the cases with only FSO-based communication

Analyses of Dual Polarization WDM and SCM Radio over Fiber and Radio over FSO for C-RAN Architecture

En este trabajo se simulan y verifican experimentalmente los esquemas de transmisión para una Arquitectura de Red de Acceso Radio Centralizada (C-RAN) basados en la combinación de dos tecnologías: Radio sobre Fibra (RoF) y Radio sobre FSO (RoFSO). Las configuraciones propuestas se optimizan para la evolución a largo plazo (LTE) con un ancho de banda de 20 MHz utilizando una modulación de amplitud en cuadratura de 64-QAM en términos de magnitud de vector de error (EVM). En primer lugar, se comparan las mediciones de la multiplexación por división de polarización mediante la combinación de RoF y RoFSO (PDM-RoF/FSO) con los modelos de simulación. Esto se amplía con la combinación de PDM-Multiplexación por División por Longitud de Onda (WDM)-RoF/FSO y PDM-Multiplexación por Subportadora (SCM)-RoF/FSO, respectivamente. Los resultados indican un mejor rendimiento de PDM-SCM-RoF/FSO que de WDM RoF/RoFSO en términos de potencia de lanzamiento para alcanzar el límite EVM.JCI-2012-14805SGS14/190/OHK3/3T/13In this paper, the transmission schemes for Centralized Radio Access Network Architecture (C-RAN) based on combination of two technologies - Radio over Fiber (RoF) and Radio over FSO (RoFSO) are simulated and experimentally verified. The proposed setups are optimized for Long Term Evolution (LTE) with 20 MHz bandwidth using 64 Quadrature amplitude modulation in terms of Error Vector Magnitude (EVM). At the first, the measurements of Polarization Division Multiplexing using combination of RoF a RoFSO (PDM-RoF/FSO) is compared with simulation models. This is further extended by combination of PDM-Wavelength Division Multiplexing (WDM)-RoF/FSO and PDM-Subcarrier Multiplexing (SCM)-RoF/FSO, respectively. Results indicate better performance of PDM-SCM-RoF/FSO than WDM RoF/RoFSO in terms of launch power to reach EVM limit

Characterization of dual-polarization analogue radio over fiber fronthaul for LTE C-RAN architecture

En este artículo se presentan los resultados de la medición ampliada de la radio analógica de doble polarización (DP) sobre fibra (RoF) en una arquitectura de red de acceso radio en la nube (C-RAN) de evolución a largo plazo (LTE). Esta técnica se propone para las conexiones de fibra entre las oficinas centrales y las estaciones base remotas. Se investigan varias longitudes de fibra óptica para determinar el mejor rendimiento del sistema en términos de magnitud de vector de error (EVM) y tasa de error de bit. La distancia máxima alcanzada para el caso de un ancho de banda LTE de 20 MHz es de 50 km, mostrando un valor de EVM admisible del 8,5% a la frecuencia de radio de 2,6 GHz cuando se utiliza el esquema de modulación 64 QAM.JCI-2012-14805SGS14/190/OHK3/3T/13COST Action IC1101 OPTICWISEIn this paper the results from extended measurement of dual-polarization (DP) analogue radio over fiber (RoF) in a long term evolution (LTE) cloud radio access network (C-RAN) architecture are presented. This technique is proposed for fiber connections between central offices and remote base stations. Investigation of various optical fiber length is carried out to determine the best system performance in terms of error vector magnitude (EVM) and bit error rate. Maximal achieved distance for the case of LTE bandwidth of 20 MHz is 50 km displaying permissible EVM value of 8.5 % at the radio frequency of 2.6 GHz when using 64 QAM modulation scheme