Implementación de la señalización de una estación base GSM

El fin de este proyecto estaba centrado en un único punto: Desarrollar la implementación de funcionalidades de una Estación Base de GSM (BTS) en una plataforma Software Defined Radio a través del NI USRP. En concreto se propuso implementar varios de los canales de control y sus procedimientos para que futuros estudiantes de los grados Ingeniería en Sistemas de Comunicaciones e Ingeniería en Tecnologías de Telecomunicación puedan realizar unas prácticas de laboratorio más reales en las asignaturas Comunicaciones Móviles y Planificación de Redes Móviles. Por tanto, las funciones a desarrollar van orientadas al usuario y a cómo un alumno podrá interactuar con los dispositivos y el programa diseñado. Un sistema completo estaría compuesto por un transmisor y un receptor. Sin embargo, debido a que el TFG está muy acotado en el tiempo, se ha preferido optar por el transmisor en primer lugar y dejar el receptor para futuras líneas de trabajo. Para que se puedan realizar prácticas de manera adecuada utilizando el trabajo desarrollado, el sistema deberá ser flexible de tal forma que se pueda manipular por parte de usuarios que no estén familiarizados con el entorno, ofreciendo así una interfaz intuitiva con los pasos bien definidos. Los párrafos anteriores hablan del mayor propósito que se planteó cuando se comenzó el TFG. Sin embargo, es evidente que para conseguir ese resultado hay que pasar por unas fases previas e ir cumpliendo paso a paso los hitos marcados. Esto se verá en el Cronograma y se explicará en profundidad en el apartado de Diseño y Desarrollo.Ingeniería de Sistemas de Comunicacione

DCO-OFDM Signals With Derated Power for Visible Light Communications Using an Optimized Adaptive Network-Based Fuzzy Inference System

Direct current-biased optical orthogonal frequency division multiplexing (DCO-OFDM) signals used in visible light communications suffer from high peak-to-average-power ratio (PAPR) or cubic metric (CM). It strongly degrades the performance due to the great back-off necessary to avoid the clipping effect in the light-emitting diode. Thus, PAPR and CM reduction techniques become crucial to improve the system performance. In this paper, an adaptive network-based fuzzy inference system (ANFIS) is used to obtain efficient DCO-OFDM signals with a low power envelope profile. First, signals specially designed for DCO-OFDMwith very low CM, as the ones obtained from the raw cubic metric (RCM)-active constellation extension method, are used to train the fuzzy systems in time and frequency domains. Second, after the off-line training, the ANFIS can generate a real-valued signal in a one-shot way with 8.9 dB of RCM reduction from the original real-valued signal, which involves a gain in the input power back off larger than 2.8 dB, an illumination-to-communication conversion efficiency gain of more than 35% and considerable improvements in bit error rate

Lights and Shadows: A Comprehensive Survey on Cooperative and Precoding Schemes to Overcome LOS Blockage and Interference in Indoor VLC

Visible light communications (VLC) have received significant attention as a way of moving part of the saturated indoor wireless traffic to the wide and unregulated visible optical spectrum. Nowadays, VLC are considered as a suitable technology, for several applications such as high-rate data transmission, supporting internet of things communications or positioning. The signal processing originally derived from radio-frequency (RF) systems such as cooperative or precoding schemes can be applied to VLC. However, its implementation is not straightforward. Furthermore, unlike RF transmission, VLC present a predominant line-of-sight link, although a weak non-LoS component may appear due to the reflection of the light on walls, floor, ceiling and nearby objects. Blocking effects may compromise the performance of the aforementioned transmission schemes. There exist several surveys in the literature focused on VLC and its applications, but the management of the shadowing and interference in VLC requires a comprehensive study. To fill this gap, this work introduces the implementation of cooperative and precoding schemes to VLC, while remarking their benefits and drawbacks for overcoming the shadowing effects. After that, the combination of both cooperative and precoding schemes is analyzed as a way of providing resilient VLC networks. Finally, we propose several open issues that the cooperative and precoding schemes must face in order to provide satisfactory VLC performance in indoor scenarios.This work has been supported partially by Spanish National Project TERESA-ADA(TEC2017-90093-C3-2-R) (MINECO/AEI/FEDER, UE), the research project GEOVEOLUZ-CM-UC3Mfunded by the call “Programa de apoyo a la realización de proyectos interdisciplinares de I+D parajóvenes investigadores de la Universidad Carlos III de Madrid 2019-2020” under the frame ofthe Convenio Plurianual Comunidad de Madrid-Universidad Carlos III de Madrid and projectMadrid Flight on Chip (Innovation Cooperative Projects Comunidad of Madrid - HUBS 2018/MadridFlightOnChip). Additionally, it has been supported partially by the Juan de la CiervaIncorporación grant IJC2019-040317-I and Juan de la Cierva Formación grant (FJC2019-039541-I/AEI/10.13039/501100011033)

Cooperative transmission scheme to address random orientation and blockage events in VLC systems

© 2019 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.Visible light communication (VLC) is a promising communication technology that paves the way to the Internet of Things. The forthcoming Industry 4.0 requires reliable high-speed communication links, which can be easily fulfilled with the massive adoption of the VLC technology. However, in VLC indoor communication environments, line-of-sight link blockages and strong misalignment losses between the light-emitting diode (LED) transmitters and the photodiode (PD) receivers are usual problems that must be tackled. This paper proposes a coordinated multi-point (CoMP) transmission technique to deal with both issues, and carries out a detailed evaluation of the VLC system performance as function of the PD receiver orientation and the density of obstacles in different scenarios. The proposed cooperative transmission scheme demonstrates an improvement in the average cell data rate and outage probability performance and, as a consequence, justifies the use of CoMP techniques to provide reliable VLC services in ultra-dense small cell scenarios indoors.Peer ReviewedPostprint (published version

Learning Mobile Communications Standards through Flexible Software Defined Radio Base Stations

Mobile communications are today widespread and contribute to the development of our society. Every day new devices include some means of wireless transmission, which is becoming ubiquitous with the Internet of Things. These systems are standardized by international organizations such as the IEEE, 3GPP, and ETSI, among others. Even though knowledge of wireless standards is key to the understanding of these systems, wireless communications are quite often taught in engineering degrees in a traditional way, without much emphasis on the standardization. Moreover, strong focus is often placed on the theoretical performance analysis rather than on practical implementation aspects. In contrast, most of the current applications make extensive use of mobile data, and the global users' satisfaction is highly correlated with the mobile data throughput. Thus, modern wireless engineers need to have deep insight on the standards that define the mobile transmission systems, and this knowledge is not acquired following the traditional theoretical teaching schemes. In this article, a new learning approach is described. This novel paradigm is based on a new flexible hardware/software platform (FRAMED-SOFT), which is also detailed. Although the article is focused on two wireless standards, GSM and UMTS, the work discussed in this article can easily be extended to other standards of interest, such as LTE and beyond, WiFi, and WiMAX

Resource Allocation for Cooperative Transmission in Optical Wireless Cellular Networks With Illumination Requirements

This work has been partially funded by the Spanish MECD FPU fellowship program granted to the author Borja Genovés Guzmán, the Catalan Government under Grant 2017-SGR-1479, and the Spanish Government under the national project ’TERESA-ADA’ with ID no. TEC2017-90093-C3-2-R and TEC2017-90093-C3-1-R (MINECO/AEI/FEDER, UE)

Robust Cooperative Multicarrier Transmission Scheme for Optical Wireless Cellular Networks

Visible light communication (VLC) is a promising technology to achieve high data rates in heterogeneous scenarios. However, VLC strongly depends on the existence of a line-of-sight (LoS) link between transmitter and receiver to guarantee a good data rate performance, which is often a condition that is difficult to satisfy in practice. In this letter, a novel cooperative multicarrier transmission scheme is proposed, where neighboring attocells smartly cooperate to decrease the probability of blockage in the LoS link. This approach is compared to single-cell transmission schemes, obtaining notable gains in both received signal-to-interference-plus-noise ratio and cell data rate when blockage of the LoS link occurs toward the nearest base station.This work was supported in part by the Catalan Government under Grant 2014SGR1567 and in part by the Spanish Government under the National Project "ELISA" with ID TEC2014-59255-C3-3/1-R. The work of B. Genovés Guzmán was supported in part by the Spanish MECD FPU Fellowship Program

Downlink Performance of Optical OFDM in Outdoor Visible Light Communication

Visible light communication (VLC) is a promising ubiquitous design alternative for supporting high data rates. Its application has been primarily oriented to indoor scenarios, but the proliferation of light-emitting diodes in the streets warrants its investigation in outdoor scenarios as well. This paper studies the feasibility of VLC in a conventional outdoor scenario, when optical orthogonal frequency division multiplexing techniques are employed. The presence of sunlight reduces the system's performance, hence sophisticated adaptive techniques must be applied. Closed-form expressions of the signal-to-noise ratio and of the mean cell data rate are derived and our simulations demonstrate their accuracy. Besides, the outage probability when adaptive modulation and coding schemes are employed is analytically expressed. It is shown that, when modulation bandwidth adaptation is carried out depending on the time of day and the illuminance from ambient light, the mean cell data rate is increased and the outage probability is reduced.This work was supported in part by the Spanish National ELISA Project under Grant TEC2014-59255-C3-3-R, the TERESA-ADA Project under MINECO/AEI/FEDER, UE Grant TEC2017-90093-C3-2-R and the 5RANVIR Project under MINECO/AEI/FEDER, UE Grant TEC2016-80090-C2-1-R. The work of B. Genovés Guzmán was supported by the Spanish MECD FPU Fellowship Program. The work of M. C. Aguayo-Torres was supported by the Universidad de Málaga. The work of H. Haas was supported in part by EPSRC through the Established Career Fellowship Extension under Grant EP/R007101/1 and in part by the Wolfson Foundation and the Royal Society. The work of L. Hanzo was supported in part by EPSRC under Project EP/Noo4558/1 and Project EP/PO34284/1, in part by the Royal Society's GRFC Grant, and in part by the European Research Council's Advanced Fellow Grant QuantCom

Superimposed training-based channel estimation for miso optical-OFDM vlc

In this paper, we investigate a novel channel estimation (CE)method for multiple-input and single-output (MISO) systems in visible lightcommunication (VLC). Direct current biased optical orthogonal frequencydivision multiplexing (DCO-OFDM) is commonly used in VLC where halfof the available subcarriers are spent to guarantee a real-valued outputafter the inverse fast Fourier transform operation. Besides, dedicated subcarriers are typically used for CE, thus, many resources are wasted andthe spectral efficiency is degraded. We propose a superimposed trainingapproach for CE in MISO DCO-OFDM VLC scenarios. Analytical expressions of mean squared error (MSE) and spectral efficiency are derived whenthe least squares estimator is considered. This analysis is valid for outdoorand indoor scenarios. For the CE error, simulation results of MSE showa perfect match with analytical expressions. Moreover, results prove thatthis technique guarantees a larger spectral efficiency than previous schemeswhere dedicated pilots were used. Finally, the optimal data power allocationfactor is also analytically derived.This work was supported in part by the National Secretary of Higher Education, Science, Technology, and Innovation (SENESCYT) in Ecuador and in part by the Spanish National Project TERESA-ADA (TEC2017-90093-C3-2-R) (MINECO/AEI/FEDER, UE). The work of B. G. Guzmán was supported by the Spanish MECD FPU Fellowship Program

Performance enhancement techniques for visible light communication systems

Mención Internacional en el título de doctorThe increasing demand for ubiquitous wireless Internet access is gradually exhausting the existing radio-frequency (RF) resources. To prevent the looming spectrum crunch, the research community is considering diverse new technologies operating in higher frequency bands, such as the millimeter-wave and the visible light communication (VLC) band. The VLC solutions rely on light-emitting diodes (LEDs) that are capable of supporting high data rates on the order of Gbps. In this Thesis, VLC point-to-point issues are investigated both in indoor and outdoor scenarios. Besides, following the trend of the cell-densification to increase the system spectral efficiency, multi-cell fully networked scenarios are also considered, where cooperative transmission techniques are proposed to address the line-of-sight (LoS) link blockage and the inter-cell interference problems. When using optical orthogonal frequency division multiplexing (O-OFDM) schemes, the timedomain signal at the input of the LED has a high peak-to-average-power ratio (PAPR) or cubic metric (CM). It strongly degrades the performance due to the great back-off necessary to avoid the clipping effect in the LED. Thus, PAPR and CM reduction techniques become crucial to improve the system performance. In this Thesis, an adaptive network-based fuzzy inference system (ANFIS) is proposed to obtain efficient direct current optical orthogonal frequency division multiplexing (DCO-OFDM) signals with a low power envelope profile. First, signals especially designed for DCO-OFDM with very low CM, as the ones obtained from the raw cubic metric (RCM)–active constellation extension method, are used to train the fuzzy systems in time and frequency domains. Second, after the off-line training, the ANFIS can generate a real-valued signal in a one-shot way with a considerable RCM reduction from the original realvalued signal, which involves gains in the input power back-off, illumination-to-communication conversion efficiency and considerable improvements in bit error rate. The application of VLC has been primarily oriented to indoor scenarios, but the proliferation of LEDs in the streets warrants its investigation in outdoor scenarios as well. This Thesis presents a pioneering study about the feasibility of VLC in a conventional outdoor scenario, when O-OFDM techniques are employed. The presence of sunlight reduces the system performance, hence sophisticated adaptive techniques must be applied. Closed-form expressions of the signal-to-noise ratio (SNR) and of the mean cell data rate are derived and simulations demonstrate their accuracy. Besides, the outage probability when adaptive modulation and coding schemes are employed is analytically expressed. It is shown that, when modulation bandwidth adaptation is carried out depending on the time of day and the illuminance from ambient light, the mean cell data rate is increased, and the outage probability is reduced. VLC strongly depends on the existence of a LoS link between the transmitter and the receiver to guarantee a good data rate performance, which is often a condition that is difficult to satisfy in practice. When a multi-cell VLC system is deployed, cooperative transmission schemes can be implemented in order to decrease the detrimental effect of LoS-link blockages and the high inter-cell interference levels commonly produced in such scenarios. An initial study based on a single-carrier scheme is proposed for corridor scenarios. The main idea behind the proposal is a simple cooperative transmission scheme where the receiver terminal will obtain the signal from different APs at the same time using a pulse position division multiplexing technique. This proposal outperforms traditional VLC schemes, especially when there is a LoS-link blockage, where around 3 dB of gain with respect to traditional schemes can be obtained for unoptimized parameters, and larger than 3 dB could be easily achieved. Due to the advantages that multi-carrier schemes such as O-OFDM offer, cooperative transmission techniques based on O-OFDM schemes are studied. A preliminary study is presented, which is based on phosphor-coated white LEDs and time division multiple access (TDMA). The potential of cooperative transmission schemes in O-OFDM schemes is notable, but the use of TDMA decreases the cell data rate considerably and new alternatives must be investigated. Thus, red-green-blue(-yellow) (RGB(Y)) illumination technology and wavelength division multiplexing (WDM) are proposed to increase the communication dimensions and flexibility of the VLC system, avoiding the use of TDMA. This Thesis studies different resource allocation patterns for multi-cell cooperative transmission schemes when tri- and tetra-chromatic LEDs and O-OFDM are utilized. Firstly, guidelines are derived for maintaining the same spatial distribution of the signal-to-interference-plus-noise ratio (SINR) in every sector of the multicell environment in case of single-point (non-cooperative) and multi-point (cooperative) transmission. Thanks to this spatial homogeneity property, the performance characterization in the whole coverage area is simplified to the study of the SINR in a reference sector and cell. Secondly, all the possible transmission schemes are classified in terms of the LED type and available orthogonal resources (number of frequency sub-bands per color and number of sectors per cell). The achievable data rate of each of the possible transmission schemes is evaluated under different realistic working conditions. Finally, the performance gain of different cooperation strategies among APs is also studied. The obtained results confirmed that the proper design of cooperative transmission schemes will be of paramount importance to improve the performance of ultra-dense VLC systems. Finally, interconnection among APs is essential in a current multi-cell VLC network that can perform as a wireless local area network (WLAN), but this fully networked scenario is not easy to implement, especially in large rooms where the number of APs is large. Thus, an alternative reflection-based wireless cooperative system is proposed, where no wires are required to interconnect APs. SNR and data rate analyses are developed, showing a proper performance and validating analytical results with simulations. Finally, an analysis of the time delay is carried out that confirms this proposal is a valid and easy alternative to deploy robust and cooperative transmission schemes in VLC-based 5G systems.Programa de Doctorado en Multimedia y Comunicaciones por la Universidad Carlos III de Madrid y la Universidad Rey Juan CarlosPresidente: Mounir Ghogho.- Secretario: Máximo Morales Céspedes.- Vocal: Majid Safar