Optical Wireless and Millimeter Waves for 5G Access Networks

Growing bandwidth demands are driving the search for increased network capacity leading to the exploration of new wavelength ranges for future communication systems. Therefore, we consider two technologies that offer increased transmission bandwidths by virtue of their high carrier frequencies, namely optical wireless and millimeter-wave transmission. After highlighting the relevant electromagnetic (EM) spectrum region, we briefly describe the applications and properties of each approach coupled with a short history of their development. This is followed by a performance comparison in two possible 5G links: outdoor point-to-point and indoor hotspots. We find that in both cases, there are regions where optical wireless communications (OWC) are better, but others where millimeter waves are to be preferred. Specifically, the former outperforms the latter over distances up to approximately 50 meters outdoors and a 10-meter hotspot radius indoors

A Cost and Power Feasibility Analysis of Quantum Annealing for NextG Cellular Wireless Networks

In order to meet mobile cellular users' ever-increasing data demands, today's 4 G and 5 G wireless networks are designed mainly with the goal of maximizing spectral efficiency. While they have made progress in this regard, controlling the carbon footprint and operational costs of such networks remains a long-standing problem among network designers. This paper takes a long view on this problem, envisioning a NextG scenario where the network leverages quantum annealing for cellular baseband processing. We gather and synthesize insights on power consumption, computational throughput and latency, spectral efficiency, operational cost, and feasibility timelines surrounding quantum annealing technology. Armed with these data, we project the quantitative performance targets future quantum annealing hardware must meet in order to provide a computational and power advantage over CMOS hardware, while matching its whole-network spectral efficiency. Our quantitative analysis predicts that with 82.32 μ s problem latency and 2.68 M qubits, quantum annealing will achieve a spectral efficiency equal to CMOS while reducing power consumption by 41 kW (45% lower) in a Large MIMO base station with 400 MHz bandwidth and 64 antennas, and a 160 kW power reduction (55% lower) using 8.04 M qubits in a CRAN setting with three Large MIMO base stations

Fully Integrated Biochip Platforms for Advanced Healthcare

Recent advances in microelectronics and biosensors are enabling developments of innovative biochips for advanced healthcare by providing fully integrated platforms for continuous monitoring of a large set of human disease biomarkers. Continuous monitoring of several human metabolites can be addressed by using fully integrated and minimally invasive devices located in the sub-cutis, typically in the peritoneal region. This extends the techniques of continuous monitoring of glucose currently being pursued with diabetic patients. However, several issues have to be considered in order to succeed in developing fully integrated and minimally invasive implantable devices. These innovative devices require a high-degree of integration, minimal invasive surgery, long-term biocompatibility, security and privacy in data transmission, high reliability, high reproducibility, high specificity, low detection limit and high sensitivity. Recent advances in the field have already proposed possible solutions for several of these issues. The aim of the present paper is to present a broad spectrum of recent results and to propose future directions of development in order to obtain fully implantable systems for the continuous monitoring of the human metabolism in advanced healthcare applications

Development of an integrated silicon photonic transceiver for access networks

Debido a la imparable aparición de dispositivos móviles multifunción junto con aplicaciones que requieren cada vez más un mayor ancho de banda en cualquier momento y en cualquier lugar, las futuras redes de acceso deberán ser capaces de proporcionar servicios tanto inalámbricos como cableados. Es por ello que una solución a seguir es el uso de sistemas de comunicaciones ópticas como medio de transporte de señales inalámbricas en enlaces de radio sobre fibra. Con ello, se converge a un dominio óptico reduciendo y aliviando el cuello de botella entre los estándares de acceso inalámbrico y cableado. En esta tesis, como parte de los objetivos establecidos en el proyecto europeo HELIOS en el que está enmarcada, se han investigado y desarrollado los bloques funcionales básicos necesarios para realizar un transceptor fotónico integrado trabajando en el rango de longitudes de onda milimétricas, y haciendo uso de los formatos de modulación más robustos y que mejor se adaptan al ámbito de aplicación considerado. El trabajo que se presenta en esta tesis se puede dividir básicamente en tres partes. La primera de ellas ofrece una descripción general de los beneficios del uso de la fotónica en silicio para el desarrollo de enlaces inalámbricos a velocidades de Gbps, así como el estado del arte de los transceptores desarrollados por los grupos de investigación más activos y punteros para satisfacer las necesidades de mercado, cada vez más exigentes. La segunda parte se centra en el estudio y desarrollo del transmisor integrado de onda milimétrica. Primero realizamos una breve introducción teórica tanto del funcionamiento de los dispositivos que forman parte del transmisor, como a los formatos de modulación existentes, centrando la atención en la modulación por desplazamiento de fase (PSK) que es la que se va a utilizar en el desarrollo de los dispositivos implicados, y más concretamente en la modulación (diferencial) de fase en cuadratura ((D)QPSK). También se presentan los bloques básicos que integran nuestro transmisor y se fijan las especificaciones que deben cumplir dichos bloques para conseguir una transmisión libre de errores. El transmisor está compuesto por un filtro/demultiplexor encargado de separar dos portadoras ópticas separadas una frecuencia de 60 GHz. Una de estas portadoras es modulada al pasar por un modulador DQPSK basado en una estructura de dos MachZehnders (MZs) anidados, para ser nuevamente combinada con la otra portadora óptica que se ha mantenido intacta. Una vez combinadas, éstas son fotodetectadas para ser transmitidas inalámbricamente. En la tercera parte de esta tesis, se investiga el uso de un esquema de diversidad en polarización junto a un receptor DQPSK integrado para la demodulación de la señal recibida. El esquema de diversidad en polarización está formado básicamente por dos bloques: un separador de polarización con el objetivo de separar la luz a la entrada del chip en sus dos componentes ortogonales; y un rotador de polarización. En lo que se refiere al receptor DQPSK propiamente dicho, se ha investigado y optimizado cada uno de los bloques funcionales que lo componen. Éstos son básicamente un divisor de potencia termo-ópticamente sintonizable basado en un interferómetro MZ, en serie con un interferómetro MZ que introduce un retardo de duración de un bit en uno de sus brazos, para obtener una correcta demodulación diferencial. El siguiente bloque que forma parte de nuestro receptor DQPSK es un 2x4 acoplador de interferencia multimodal actuando como un híbrido de 90 grados, cuyas salidas van a parar a dos fotodetectores balanceados de germanio. Las contribuciones principales de esta tesis han sido: ¿ Demostración de un filtro/demultiplexor con tres grados de sintonización con una relación de extinción superior a 25dB. ¿ Demostración de un rotador con una longitud de tan sólo 25µm y CMOS compatible. ¿ Demostración de un modulador DPSK a una velocidad máxima de 20 Gbit/s. ¿ Demostración de un demodulador DQPSK a una velocidad máxima de 20 Gbit/s.Due to the relentless emergence of multifunction mobile devices with applications that require increasingly greater bandwidth at anytime and anywhere, future access networks must be capable of providing both wireless and wired services. The use of optical communications systems as transport medium of wireless signals over fiber radio links is a steady solution to be taken into account. This will make possible a convergence to an optical domain reducing and alleviating the bottleneck between wireless access standards and current wired access. In this thesis, as part of the objectives of the European project HELIOS in which it is framed, we have investigated and developed the basic functional blocks needed to achieve an integrated photonic transceiver working in the range of millimetre wavelengths, and using robust modulation formats that best fit the scope considered. The work presented in this thesis can be basically divided into three parts. The first one provides an overview of the benefits of using silicon photonics for the development of wireless links at rates of Gbps, and the state of the art of the transceivers reported by the most important research groups in order to meet the increasingly demanding needs¿ market. The second part focuses on the study and development of millimetre-wave integrated transmitter. First we provide a brief theoretical introduction of the operation principles of the devices involved in the transmitter such as a modulation formats, focusing on the phase shift keying (PSK) which is the one that will be used, particularly the (differential) quadrature phase shift keying ((D) QPSK). We also present the building blocks involved in our transmitter and we set the specifications that must be met by these devices in order to achieve an error-free transmission. The transmitter includes a filter/demultiplexer which must separate two optical carriers 60 GHz separated. One of these optical carriers is modulated by passing through a DQPSK Mach-Zehnder-based modulator (MZM) by arranging two MZMs in a nested configuration. Using a combiner, the modulated optical signal and the un-modulated carrier are combined and photodetected to be transmitted wirelessly. In the third part of this thesis, we investigate the use of a polarization diversity scheme with an integrated DQPSK receiver for demodulating of the wireless signal. The polarization diversity scheme basically consists of two blocks: a polarization splitter in order to separate the random polarization state of the incoming light into its two orthogonal components, and a polarization rotator. Regarding the DQPSK receiver itself, all the functional blocks that comprise it have been investigated and optimized. It basically includes a thermo-optically tunable MZ interferometer power splitter, in series with a MZ interferometer that introduces, in one of its arms, a delay of one bit length in order to obtain a correct differential demodulation. The next building block of our DQPSK receiver is a 2x4 multimode interference coupler acting as a 90 degree hybrid, whose outputs are connected to two balanced germanium photodetectors. The main contributions of this thesis are: ¿ Demonstration of a filter/demultiplexer with three degrees of tuning and an extinction ratio greater than 25dB. ¿ Demonstration of a polarization rotator with a length of only 25¿m and CMOS compatible. ¿ Demonstration of a DPSK modulator at a maximum rate of 20 Gbit/s. ¿ Demonstration of a DQPSK demodulator to a maximum rate of 20 Gbit/s.Aamer, M. (2013). Development of an integrated silicon photonic transceiver for access networks [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/31649TESI

Are Brain-Computer Interfaces Feasible withIntegrated Photonic Chips?

The present paper examines the viability of a radically novel idea for brain-computer interface (BCI), which could lead to novel technological, experimental and clinical applications. BCIs are computer-based systems that enable either one-way or two-way communication between a living brain and an external machine. BCIs read-out brain signals and transduce them into task commands, which are performed by a machine. In closed-loop the machine can stimulate the brain with appropriate signals. In recent years, it has been shown that there is some ultraweak light emission from neurons within or close to the visible and near-infrared parts of the optical spectrum. Such ultraweak photon emission (UPE) reflects the cellular (and body) oxidative status, and compelling pieces of evidence are beginning to emerge that UPE may well play an informational role in neuronal functions. In fact, several experiments point to a direct correlation between UPE intensity and neural activity, oxidative reactions, EEG activity, cerebral blood flow, cerebral energy metabolism, and release of glutamate. Therefore, we propose a novel skull implant BCI that uses UPE. We suggest that a photonic integrated chip installed on the interior surface of the skull may enable a new form of extraction of the relevant features from the UPE signals. In the current technology landsacepe, photonic technologies are advancing rapidly and poised to overtake many electrical technologies, due to their unique advantages, such as miniaturization, high speed, low thermal effects, and large integration capacity that allow for high yield, volume manufacturing, and lower cost. For our proposed BCI, we are making some very major conjectures, which need to be experimentally verified, and therefore we discuss the controversial parts, feasibility of technology and limitations, and potential impact of this envisaged technology if successfully implemented in the future.BERC.2018-2021 Severo Ochoa.SEV-2017-071

A Prospective Look: Key Enabling Technologies, Applications and Open Research Topics in 6G Networks

The fifth generation (5G) mobile networks are envisaged to enable a plethora of breakthrough advancements in wireless technologies, providing support of a diverse set of services over a single platform. While the deployment of 5G systems is scaling up globally, it is time to look ahead for beyond 5G systems. This is driven by the emerging societal trends, calling for fully automated systems and intelligent services supported by extended reality and haptics communications. To accommodate the stringent requirements of their prospective applications, which are data-driven and defined by extremely low-latency, ultra-reliable, fast and seamless wireless connectivity, research initiatives are currently focusing on a progressive roadmap towards the sixth generation (6G) networks. In this article, we shed light on some of the major enabling technologies for 6G, which are expected to revolutionize the fundamental architectures of cellular networks and provide multiple homogeneous artificial intelligence-empowered services, including distributed communications, control, computing, sensing, and energy, from its core to its end nodes. Particularly, this paper aims to answer several 6G framework related questions: What are the driving forces for the development of 6G? How will the enabling technologies of 6G differ from those in 5G? What kind of applications and interactions will they support which would not be supported by 5G? We address these questions by presenting a profound study of the 6G vision and outlining five of its disruptive technologies, i.e., terahertz communications, programmable metasurfaces, drone-based communications, backscatter communications and tactile internet, as well as their potential applications. Then, by leveraging the state-of-the-art literature surveyed for each technology, we discuss their requirements, key challenges, and open research problems