Wireless machine-to-machine networks 2013

Editoria

Integración de redes de sensores en las nuevas generaciones de sistemas de comunicaciones móviles 4G y 5G

El concepto actual de Internet de las Cosas (Internet of Things, IoT) y la tendencia hacia la utilización masiva de redes basadas en sensores plantea la duda de cómo va a ser posible transportar la información proveniente de dichas redes de una forma factible y eficiente. Una opción prometedora es la utilización de la red móvil celular existente (LTE/LTE-A). La realidad es que esta última no puede soportar una inclusión masiva de nodos sin afectar a los usuarios. Actualmente hay una gran actividad de investigación y estandarización tanto para adaptar las próximas versiones de las tecnologías actuales, como en la definición de la próxima generación de sistemas móviles, 5G, en la que resolver esta problemática resulta un punto clave. En las redes móviles actuales, la limitación viene más por un problema de saturación de los canales de señalización que de capacidad de la red. En el presente trabajo investigamos los aspectos de señalización del estándar de comunicaciones Long Term Evolution (LTE) para su posible uso conjunto con la red de sensores en versiones futuras y en la próxima generación. Creemos que una red de sensores con un gran número de nodos, que requiera poco uso de datos, puede interferir con los usuarios. Esto es debido a que pueden colapsar los canales de control y, por lo tanto, provocar un retraso general para todos los terminales de la red. Encontramos que efectivamente se produce este problema en el canal PUCCH, que es el principal canal de control del enlace ascendente. En este canal se asigna un recurso a cada terminal para peticiones de transmisión, por lo que al aumentar el número de terminales, el retraso aumenta proporcionalmente. Después de analizar diferentes investigaciones realizadas sobre la integración de sensores en LTE y comunicaciones tipo máquina, proponemos un modelo basado en una de ellas. Se trata de un modelo del canal de acceso aleatorio (RACH), donde los sensores realicen sus peticiones de transmisión en ese canal en vez de en el PUCCH. Sobre dicho modelo proponemos diversas modificaciones para mejorar el rendimiento y conseguir que no afecte a los usuarios que usen ese canal, como por ejemplo, la separación de los recursos del canal de acceso aleatorio (RACH) entre usuarios y sensores. Finalmente comprobamos que el modelo cumple con los objetivos mediante una simulación de tiempo discreto. Explicamos la estructura de la simulación detalladamente y verificamos los resultados mediante gráficas.The actual concept of Internet of Things (IoT) and the trend towards the massive use of sensor based networks bring up the question of how it will be possible to transport the information from these networks in a feasible and efficient way. A promising choice is using the current mobile cellular network (LTE/LTE-A). But the reality is that it can’t support a massive inclusion of nodes without affecting the users. There is currently a very active research and standardization for both adapting the next versions of the current technologies and defining the next generation of mobile systems, 5G, in which solve this problem is a key factor. In the existing mobile networks, the limitation is more a saturation problem of the signalling channels than network’s capacity. In this project we investigate the signalling aspects of 3GPP Long Term Evolution (LTE) for its possible use with the sensor network in future versions and next generation. We believe that a sensor network with a large number of nodes with low data traffic can interfere with the users due to saturation of the control channels, and, therefore, causing a general delay in all the terminals of the network. We found that, indeed, this problem occurred in the PUCCH channel, which is the main uplink control channel. In this channel it is assigned a resource to each terminal for transmission requests, hence when the number of terminals is increased, the delay increases on a proportional way. Afterwards, we make an overview about the different investigations realized concerning the sensors integration on LTE and machine type communications. Then, we propose a model based on one of them. It is random access channel (RACH) model, where the sensors use that channel to perform transmission requests instead of the PUCCH. We propose some modifications to improve the performance and to attain that it does not affect the users using that channel, like, for example, a division of the random access channel (RACH) resources between users and sensors. Finally, we prove, with a discrete time simulation, that the model fulfil the objectives. We explain the simulation structure in detail and we verify the results using graphics.Ingeniería de Sistemas de Comunicacione

D13.1 Fundamental issues on energy- and bandwidth-efficient communications and networking

Deliverable D13.1 del projecte europeu NEWCOM#The report presents the current status in the research area of energy- and bandwidth-efficient communications and networking and highlights the fundamental issues still open for further investigation. Furthermore, the report presents the Joint Research Activities (JRAs) which will be performed within WP1.3. For each activity there is the description, the identification of the adherence with the identified fundamental open issues, a presentation of the initial results, and a roadmap for the planned joint research work in each topic.Preprin

Enabling Technologies for Internet of Things: Licensed and Unlicensed Techniques

The Internet of Things (IoT) is a novel paradigm which is shaping the evolution of the future Internet. According to the vision underlying the IoT, the next step in increasing the ubiquity of the Internet, after connecting people anytime and everywhere, is to connect inanimate objects. By providing objects with embedded communication capabilities and a common addressing scheme, a highly distributed and ubiquitous network of seamlessly connected heterogeneous devices is formed, which can be fully integrated into the current Internet and mobile networks, thus allowing for the development of new intelligent services available anytime, anywhere, by anyone and anything. Such a vision is also becoming known under the name of Machine-to-Machine (M2M), where the absence of human interaction in the system dynamics is further emphasized. A massive number of wireless devices will have the ability to connect to the Internat through the IoT framework. With the accelerating pace of marketing such framework, the new wireless communications standards are studying/proposing solutions to incorporate the services needed for the IoT. However, with an estimate of 30 billion connected devices, a lot of challenges are facing the current wireless technology. In our research, we address a variety of technology candidates for enabling such a massive framework. Mainly, we focus on the nderlay cognitive radio networks as the unlicensed candidate for IoT. On the other hand, we look into the current efforts done by the standardization bodies to accommodate the requirements of the IoT into the current cellular networks. Specifically, we survey the new features and the new user equipment categories added to the physical layer of the LTE-A. In particular, we study the performance of a dual-hop cognitive radio network sharing the spectrum of a primary network in an underlay fashion. In particular, the cognitive network consists of a source, a destination, and multiple nodes employed as amplify-and-forward relays. To improve the spectral efficiency, all relays are allowed to instantaneously transmit to the destination over the same frequency band. We present the optimal power allocation that maximizes the received signal-to-noise ratio (SNR) at the destination while satisfying the interference constrains of the primary network. The optimal power allocation is obtained through an eigen-solution of a channel-dependent matrix, and is shown to transform the transmission over the non-orthogonal relays into parallel channels. Furthermore, while the secondary destination is equipped with multiple antennas, we propose an antenna selection scheme to select the antenna with the highest SNR. To this end, we propose a clustering scheme to subgroup the available relays and use antenna selection at the receiver to extract the same diversity order. We show that random clustering causes the system to lose some of the available degrees of freedom. We provide analytical expression of the outage probability of the system for the random clustering and the proposed maximum-SNR clustering scheme with antenna selection. In addition, we adapt our design to increase the energy-efficiency of the overall network without significant loss in the data rate. In the second part of this thesis, we will look into the current efforts done by the standardization bodies to accommodate the equirements of the IoT into the current cellular networks. Specifically, we present the new features and the new user equipment categories added to the physical layer of the LTE-A. We study some of the challenges facing the LTE-A when dealing with Machine Type communications (MTC). Specifically, the MTC Physical Downlink control channel (MPDCCH) is among the newly introduced features in the LTE-A that carries the downlink control information (DCI) for MTC devices. Correctly decoding the PDCCH, mainly depends on the channel estimation used to compensate for the channel errors during transmission, and the choice of such technique will affect both the complexity and the performance of the user equipment. We propose and assess the performance of a simple channel estimation technique depends in essence on the Least Squares (LS) estimates of the pilots signal and linear interpolations for low-Doppler channels associated with the MTC application

Radio Communications

In the last decades the restless evolution of information and communication technologies (ICT) brought to a deep transformation of our habits. The growth of the Internet and the advances in hardware and software implementations modified our way to communicate and to share information. In this book, an overview of the major issues faced today by researchers in the field of radio communications is given through 35 high quality chapters written by specialists working in universities and research centers all over the world. Various aspects will be deeply discussed: channel modeling, beamforming, multiple antennas, cooperative networks, opportunistic scheduling, advanced admission control, handover management, systems performance assessment, routing issues in mobility conditions, localization, web security. Advanced techniques for the radio resource management will be discussed both in single and multiple radio technologies; either in infrastructure, mesh or ad hoc networks

A review of gallium nitride LEDs for multi-gigabit-per-second visible light data communications

The field of visible light communications (VLC) has gained significant interest over the last decade, in both fibre and free-space embodiments. In fibre systems, the availability of low cost plastic optical fibre (POF) that is compatible with visible data communications has been a key enabler. In free-space applications, the availability of hundreds of THz of the unregulated spectrum makes VLC attractive for wireless communications. This paper provides an overview of the recent developments in VLC systems based on gallium nitride (GaN) light-emitting diodes (LEDs), covering aspects from sources to systems. The state-of-the-art technology enabling bandwidth of GaN LEDs in the range of >400 MHz is explored. Furthermore, advances in key technologies, including advanced modulation, equalisation, and multiplexing that have enabled free-space VLC data rates beyond 10 Gb/s are also outlined

Técnicas de quantização para sistemas de comunicação híbridos na banda de ondas milimétricas com um número elevado de antenas

Since the appearance of mobile communications, the users of this technology have been growing exponentially every day. The escalating mobile traffic growth it has been imposed by the proliferation of smartphones and tablets. The increasing and more intensive use of wireless communications may lead to a future breaking point, where the traditional systems will fail to support the required capability, spectral and energy efficiency. On the other hand, to cover all this current need to have more and more data it is necessary to provide a new range of data rates around the gigabits per second. Today, almost all mobile communications systems use spectrum in the range of 300MHz – 3GHz. It is needed to start looking to the range of 3GHz – 300GHz spectrum for mobile broadband applications. Millimeter waves are one way to alleviate the spectrum gridlock at lower frequencies. MIMO based systems has been researched for the last 20 years and are now part of the current standards. However, to achieve more gains, a grander view of the MIMO concept envisions the use of a large scale of antennas at each base stations, a concept referred as massive MIMO. The symbiotic combination of these technologies and other ones will lead to the development of a new generation system known as the 5G. The knowledge of the channel state information at the transmitter is very important in real massive MIMO millimeter wave systems. In this dissertation a limited feedback strategy for a hybrid massive MIMO OFDM system is proposed, where only a part of the parameters associated to the link channel are quantized and fed back. The limited feedback strategy employs a uniform-based quantization for channel amplitudes, angle of departure and angle of arrival in time domain. After being fed back, this information is used to reconstruct the overall channel in frequency domain and the transmit antenna array, which are then used to compute the hybrid analog-digital precoders. Numerical results show that the proposed quantization strategy achieve a performance close to the one obtained with perfect full channel, with a low overhead and complexityDesde o aparecimento das comunicações móveis, os utilizadores desta tecnologia têm vindo a crescer exponencialmente todos os dias. A escalada do crescimento do tráfego móvel foi imposta, principalmente, pela proliferação de smartphones e tablets. O uso crescente e intensivo das comunicações sem fios pode levar no futuro a um ponto de rutura, onde os sistemas tradicionais não suportam a capacidade requerida, a eficiência espectral e eficiência enérgica. Por outro lado, para cobrir toda esta necessidade atual de ter mais e mais dados, é necessário fornecer taxas de transmissão mais elevadas, em torno dos gigabits por segundo. Hoje, quase todos os sistemas de comunicações móveis usam espectro na faixa de 300 MHz - 3GHz. É necessário começar a procurar a gama de espectro 3GHz - 300 GHz para aplicações de banda larga móvel. Aqui vamos apresentar as ondas milimétricas, sendo esta uma maneira de aliviar espectro em frequências mais baixas. Os sistemas baseados em MIMO foram alvo de pesquisa nos últimos 20 anos e agora fazem parte dos padrões atuais. No entanto, para obter mais ganhos, uma visão mais ampla do conceito MIMO prevê o uso de uma grande quantidade de antenas em cada estação base, um conceito referido como massive MIMO. A combinação simbiótica destas tecnologias levará ao desenvolvimento de um novo sistema de geração denominado 5G. O desenvolvimento de técnicas de conhecimento da informação do canal no transmissor é muito importante em sistemas massive MIMO millimeter wave reais. Nesta dissertação é proposta e avaliada uma estratégia de envio de informação de canal para o transmissor para sistemas massive MIMO OFDM híbrido, onde apenas uma parte dos parâmetros associados ao canal são quantificados e transmitidos para o transmissor. A estratégia de feedback proposta é baseada numa quantização uniforme das amplitudes de canal, ângulos de partida e de chegada, no domínio do tempo. Depois de serem enviadas, essas informações são usadas para reconstruir o canal geral no domínio da frequência e a matriz da antena de transmissão, que são então usadas para obter os precoders híbridos analógico-digitais. Os resultados numéricos mostram que a estratégia de quantificação proposta atinge um desempenho próximo ao obtido caso se conhecesse o canal perfeito no transmissor, com um baixo overhead e complexidadeMestrado em Engenharia Eletrónica e Telecomunicaçõe