Raul Gomez Cid-Fuentes

A receiver architecture for pulse-based electromagnetic nanonetworks in the Terahertz Band

Graphene-enabled wireless communications set the Terahertz Band as the frequency band of operation of future nanodevices (0.1-10 THz). Amongst others, femtosecond-long pulse-based modulation schemes have been recently proposed to enable the communication among nanodevices. Within this context, a receiver architecture suitable for nanodevices must be ultra compact, must have high sensitivity and must be ultra-low power. Unfortunately, common receiver architectures used in other communication schemes, such as IR-UWB, show a strong compromise between low complexity and performance. In this paper, a novel receiver architecture for pulse-based communication based on a Continuous-time Moving Average (CTMA) symbol detection scheme is presented. This scheme bases its symbol decision on the received signal power maximum peak after the CTMA, which is implemented with a single low-pass filter. Moreover, an analytical model for the symbol detection is provided and it is quantitatively shown that the proposed CTMA scheme outperforms previous symbol detection schemes for pulse-based modulations in terms of Symbol Error Rate (SER). The low complexity and relaxed synchronization needed for this symbol detector makes this structure specially suited for the development of future transceivers for nano-devices.

Energy Buffer Dimensioning Through Energy-Erlangs in Spatio-Temporal-Correlated Energy-Harvesting-Enabled Wireless Sensor Networks

Energy-harvesting-enabled wireless sensor networks (EHE-WSN), despite their disruptive potential impact, still present several challenges precluding practical deployability. In particular, the low power density and random character of the ambient energy sources produce slow deep fadings in the energy that nodes harvest. Unfortunately, the capacity of the energy buffers is very limited, causing that, at some times, the node might interrupt its operation due to lack of stored energy. In this context, a general purpose framework for dimensioning the energy buffer is provided in this work. To achieve this, a dynamics-decoupled, multi-source capable energy model is presented, which can handle fast random patterns of the communications and the energy harvesting, while it can capture slow variations of the ambient energy in both time and space. By merging both dynamics, the model can more accurately evaluate the performance of the sensor node in terms of the energy storage capacity and to estimate the expected energy of the neighboring nodes. In order to evaluate the performance of the sensor node, a statistical unit for energy harvesting resources, referred as the Energy-Erlang (E2), has been defined. This unit provides a link between the energy model, the environmental harvested power and the energy buffer. The results motivate the study of the specific properties of the ambient energy sources before the design and deployment. By combining them in this general-purpose framework, electronics and network designers will have a powerful tool for optimizing resources in EHE-WSNs.

Electronically tunable switch-mode high-efficiency adaptive band-pass filters for energy harvesting applications

Wireless Sensor Networks (WSN) present a pending challenge for a complete deployability due to energy requirements. The Self-Powered WSN approach aims to extend the sensor node life by means of Energy Harvesting. The harvested energy presents an erratic behavior in both time and frequency. In this paper, a new concept of switch-mode electronically tunable band-pass filters is presented to adaptively follow the power source variations and to maximize the power transfer. To implement these switch-mode filters, three alternatives are presented. These filter topologies are modeled and evaluated. Additionally, some design guidelines are provided. The results show how these high efficiency topologies present a band-pass behavior whose center frequency can be electronically tuned over one decade. The results target the integration of these high-efficiency switch-mode band-pass filters into the future harvesting front-ends.

MolComML: The Molecular Communication Markup Language

Given the high multi-disciplinarity of Molecular Communications (MolCom), researchers often face significant difficulties to understand each other. This impairment not only affect researchers with different backgrounds, but it also affects the different software tools. This paper motivates the development of the Molecular Communication Markup Language (MolComML). MolComML is proposed as an XML-based format to represent the considered elements, interactions, configuration and results of the experiments and simulations in the field of MolCom. MolComML is designed with the objective of converging all fields of research within MolCom to help the exchange of information. We overview its main functionality and define its basic composing elements.

Leveraging Deliberately Generated Interferences for Multi-Sensor Wireless RF Power Transmission

Wireless RF power transmission promises battery-less, resilient, and perpetual wireless sensor networks. Through the action of controllable Energy Transmitters (ETs) that operate at-a- distance, the sensors can be re-charged by harvesting the radiated RF energy. However, both the charging rate and effective charging range of the ETs are limited, and thus multiple ETs are required to cover large areas. While this action increases the amount of wireless energy injected into the network, there are certain areas where the RF energy combines destructively. To address this problem, we propose a duty-cycled random- phase multiple access (DRAMA). Non-intuitively, our approach relies on deliberately generating random interferences, both destructive and constructive, at the destination nodes. We demonstrate that DRAMA optimizes the power conversion efficiency, and the total amount of energy harvested. Through real-testbed experiments, we prove that our proposed scheme provides significant advantages over the current state of the art in our considered scenario, as it requires up to 70% less input RF power to recharge the energy buffer of the sensor in the same time.

On signaling power: Communications over wireless energy

Wireless RF power transmission from dedicated Energy Transmitters (ETs) is emerging as a promising approach to enable battery-less wireless networked sensor systems. However, when data communication and RF energy recharging occur in-band, sharing the RF medium and devoting separate access times for both operations raises architectural and protocol level challenges. This paper proposes a novel method of concurrent transmission of data and energy to solve this problem, allowing ETs to transmit energy and sensors to transmit data in the same band synchronously. Our key idea concerns devising a physical layer modulation scheme that allows the data transmitting node to introduce variations in the envelope of the energy signal at the intended recipient. We implemented a proof-of-concept receiver, modeled and validated through extensive experimentation. We then propose a new physical layer mechanism for guaranteed successful delivery of information in a point-to-point link. Quantitative results demonstrate the feasibility of joint energy-data transfer, along with its associated benefits and tradeoffs.

Area Model and Dimensioning Guidelines of Multisource Energy Harvesting for Nano–Micro Interface

Multisource energy harvesters are a promising, robust alternative to power the future Internet of Nano Things (IoNT), since the network elements can maintain their operation regardless of the fact that one of its energy sources might be temporarily unavailable. Interestingly, and less explored, when the energy availability of the energy sources present large temporal variations, combining multiple energy sources reduce the overall sparsity. As a result, the performance of a multiple energy harvester powered device is significantly better compared to a single energy source even if they harvest the same amount of energy. In this context, a framework to model and characterize the area for multiple source energy harvesting (EH) powered systems is proposed. This framework takes advantage of this improvement in performance to provide the optimal amount of energy harvesters, the requirements of each energy harvester, and the required energy buffer capacity, such that the overall area or volume is minimized. On top of these results, self-tunable energy harvesters are explored as a solution and compared to multisource EH platforms. As the results show, by conducting a joint design of the energy harvesters and the energy buffer, the overall area or volume of an EH powered device can be significantly reduced.

Releasing rate optimization in a single and multiple transmitter local drug delivery system with limited resources

Abstract Drug delivery is one of the most important applications of molecular communication. Drug transmitters have limited resources in terms of energy and reservoir and these limitations should be taken into consideration when designing a drug delivery system. Drug molecules may also be expensive and releasing a large amount of them can have harmful effects on the healthy parts of the body. In this paper, we consider a multiple transmitter local drug delivery system in which the nearest transmitters to a randomly located tumor are activated to release drug molecules and guarantee the Least Effective Concentration (LEC) in every part of the tumor. We propose two different scenarios: a single transmitter drug delivery system for which the optimal rate of the transmitting nanomachine and the optimal density of deployed nanomachines are derived through formulations and simulations. Poisson distributed as well as regular square and hexagon grid deployments are investigated. We then extend it to a multiple transmitter drug delivery system for which the optimal allocated rate to each releasing transmitter is derived in order to minimize the total rate of release and maintain LEC in every part of the tumor. It is shown that activating multiple transmitters leads to a reduction in the total optimal release rate of drug molecules as well as improving the time duration between consecutive administrations.

Influence of neighboring absorbing receivers upon the inter-symbol interference in a diffusion-based molecular communication system

Abstract A Diffusion-based Molecular Communication (DMC) system is based on the free diffusion of particles that carry the message between the transmitter and the receivers. One of the main problems which lead to decreased data rates in such network is the Inter Symbol Interference (ISI) caused by the heavy tail of the impulse response. In this paper, we study the influence of neighboring absorbing receivers upon the Inter Symbol Interference (ISI) of a Diffusion-based Molecular Communication (DMC) point-to-point link. It is shown that neighboring absorbing receivers have a noticeable impact on reducing the tail of the detected pulse-shape and, hence, higher achievable throughput are reachable.

An all-digital receiver for low power, low bit-rate applications using simultaneous wireless information and power transmission

Simultaneous Wireless Information and Power Transmission (SWIPT) has been proposed as a feasible solution to enable joint power and data transfer for the nodes of a battery-less wireless networked sensor system. Different from existing approaches, where the incident energy is split between decoding and harvesting blocks at the receiver chain, this paper describes the design and implementation of an all-digital receiver circuit. We leverage the internal control signals of the circuit, targeting ultra-low power consumption, low bit-rate applications in SWIPT. A proof-of-concept receiver is modeled, implemented using off-the-shelf hardware, and validated through extensive experiments. Quantitative results demonstrate the benefits of this joint energy-data reception approach through a single receiver chain, offering bit-rates of 400 bps.