47 research outputs found
Symbol Synchronization for Diffusive Molecular Communication Systems
Symbol synchronization refers to the estimation of the start of a symbol
interval and is needed for reliable detection. In this paper, we develop a
symbol synchronization framework for molecular communication (MC) systems where
we consider some practical challenges which have not been addressed in the
literature yet. In particular, we take into account that in MC systems, the
transmitter may not be equipped with an internal clock and may not be able to
emit molecules with a fixed release frequency. Such restrictions hold for
practical nanotransmitters, e.g. modified cells, where the lengths of the
symbol intervals may vary due to the inherent randomness in the availability of
food and energy for molecule generation, the process for molecule production,
and the release process. To address this issue, we propose to employ two types
of molecules, one for synchronization and one for data transmission. We derive
the optimal maximum likelihood (ML) symbol synchronization scheme as a
performance upper bound. Since ML synchronization entails high complexity, we
also propose two low-complexity synchronization schemes, namely a peak
observation-based scheme and a threshold-trigger scheme, which are suitable for
MC systems with limited computational capabilities. Our simulation results
reveal the effectiveness of the proposed synchronization~schemes and suggest
that the end-to-end performance of MC systems significantly depends on the
accuracy of symbol synchronization.Comment: This paper has been accepted for presentation at IEEE International
Conference on Communications (ICC) 201
Transmitter and Receiver Architectures for Molecular Communications: A Survey on Physical Design with Modulation, Coding, and Detection Techniques
Inspired by nature, molecular communications (MC), i.e., the use of molecules to encode, transmit, and receive information, stands as the most promising communication paradigm to realize the nanonetworks. Even though there has been extensive theoretical research toward nanoscale MC, there are no examples of implemented nanoscale MC networks. The main reason for this lies in the peculiarities of nanoscale physics, challenges in nanoscale fabrication, and highly stochastic nature of the biochemical domain of envisioned nanonetwork applications. This mandates developing novel device architectures and communication methods compatible with MC constraints. To that end, various transmitter and receiver designs for MC have been proposed in the literature together with numerable modulation, coding, and detection techniques. However, these works fall into domains of a very wide spectrum of disciplines, including, but not limited to, information and communication theory, quantum physics, materials science, nanofabrication, physiology, and synthetic biology. Therefore, we believe it is imperative for the progress of the field that an organized exposition of cumulative knowledge on the subject matter can be compiled. Thus, to fill this gap, in this comprehensive survey, we review the existing literature on transmitter and receiver architectures toward realizing MC among nanomaterial-based nanomachines and/or biological entities and provide a complete overview of modulation, coding, and detection techniques employed for MC. Moreover, we identify the most significant shortcomings and challenges in all these research areas and propose potential solutions to overcome some of them.This work was supported in part by the European Research Council (ERC) Projects MINERVA under Grant ERC-2013-CoG #616922 and MINERGRACE under Grant ERC-2017-PoC #780645
Diffusion-based physical channel Identification for Molecule Nanonetworks
Catal脿: El treball 茅s una exploraci贸 del canal de difusi贸 molecular per nanoredes moleculars, en el qual s'identifica la resposta impulsional i en freq眉猫ncia del canal, es comprova la seva linealitat i invari脿ncia i s'extreuen les principals caracter铆stiques de comunicaci贸. S'avaluen diferents t猫cniques de modulaci贸.Castellano: El trabajo es una exploraci贸n del canal de difusi贸n molecular para nanoredes moleculares, en el cual se identifica la respuesta impulsional y en frecuencia del canal, se comprueba su linealidad e invarianza y se extraen las principales caracter铆sticas de comunicaci贸n. Se eval煤an diferentes t茅cnicas de modulaci贸n.English: In this work, the diffusion-based MC channel is explored in order to extract its main communication metrics, such as attenuation and delay with respect to frequency and distance. The LTI property is proven to be a valid assumption for normal diffusion-based single/multi-transmitter scenarios. Different pulse-based modulation techniques are compared by means of throughput, operation range, energy requirements and ISI, and the optimal pulse shape for these modulations is provided. Finally, interferences are evaluated in a broadcast communication scenario and diffusion-based noise is observed and assessed with reference to already proposed stochastic models.The exploration of the physical diffusion-based communication channel is based on simulations
Cooperative signal amplification for molecular communication in nanonetworks.
English: Nanotechnology is enabling the development of devices in a scale ranging from a few to hundreds of nanometers. Communication between these devices greatly expands the possible applications, increasing the complexity and range of operation of the system. In particular, the resulting nanocommunication networks (or nanonetworks) show great potential for applications in the biomedical field, in which diffusion-based molecular communication is regarded as a promising alternative to electromagnetic-based solutions due to the bio-stability and energy-related requirements of this scenario. In this new paradigm, the information is encoded into pulses of molecules that reach the receiver by means of diffusion. However, molecular signals suffer a significant amount of attenuation as they propagate through the medium, thus limiting the transmission range. In this work we propose, among others, a signal amplification scheme for molecular communication nanonetworks in which a group of emitters jointly transmits a given signal after achieving synchronization by means of Quorum Sensing. By using the proposed methodology, the transmission range is extended proportionally to the number of synchronized emitters. We also provide an analytical model of Quorum Sensing, validated through simulation. This model accounts for the activation threshold (which will eventually determine the resulting amplification level) and the delay of the synchronization process.Castellano: La nanotecnolog铆a permite el desarrollo de dispositivos en una escala que va de las unidades a centenares de nan贸metros. La comunicaci贸n entre estos dispositivos hace aumentar el n煤mero de aplicaciones posibles, ya que se mejora la complejidad y el rango de actuaci贸n del sistema. En concreto, las redes de nanocomunicaciones (o nanoredes) resultantes muestran un gran potencial cuando se trata de aplicaciones biom茅dicas, en las cuales la comunicaci贸n molecular basada en difusi贸n de part铆culas supera a las soluciones electromagn茅ticas cl谩sicas debido a las imposiciones energ茅ticas y de biocompatibilidad de este escenario. En este nuevo paradigma de comunicaci贸n, la informaci贸n se codifica en pulsos de mol茅culas que llegan al receptor gracias al fen贸meno de la difusi贸n. No obstante, las se帽ales moleculares son sometidas a una gran atenuaci贸n a medida que se propagan a trav茅s del medio, hecho que limita severamente el alcance o rango de transmisi贸n. En esta tesis se propone, entre otros, un esquema de amplificaci贸n de la se帽al para nanoredes de comunicaci贸n molecular, en el cual un grupo de emisores transmite una cierta se帽al de manera conjunta despu茅s de haberse sincronizado mediante la ejecuci贸n de Quorum Sensing. Con el m茅todo que proponemos, el alcance aumenta proporcionalmente al n煤mero de transmisores que se sincronizan. Adem谩s, proponemos un modelo anal铆tico de Quorum Sensing, el cual se valida mediante simulaci贸n. Dicho modelo permite calcular el nivel umbral de activaci贸n del conjunto (hecho que determina la amplificaci贸n resultante y el rango de transmisi贸n final) y el retardo que el proceso de sincronizaci贸n introduce.Catal脿: La nanotecnologia permet el desenvolupament de dispositius en una escala de unitats a centenars de nan貌metres. La comunicaci贸 entre aquests dispositius fa augmentar el nombre de possibles aplicacions, ja que es millora la complexitat i el rang d'actuaci贸 del sistema. En concret, les xarxes de nanocomunicacions (o nanoxarxes) resultants mostren un gran potencial quan ens referim a aplicacions biom猫diques, en les quals la comunicaci贸 molecular basada en difusi贸 de part铆cules supera a les solucions de caire electromagn猫tic degut a les imposicions energ猫tiques i de biocompatilitat d'aquest escenari. En aquest nou paradigma de comunicaci贸, la informaci贸 茅s codificada en polsos de mol猫cules que arriben al receptor gr脿cies al fenomen de la difusi贸. No obstant, els senyals moleculars s贸n sotmesos a una gran atenuaci贸 a mesura que es propaguen a trav茅s del medi, fet que limita severament el rang de transmissi贸. En aquesta tesi es proposa, entre d'altres, un esquema d'amplificaci贸 del senyal per a nanoxarxes de comunicaci贸 molecular, en el qual un grup d'emissors transmet un cert senyal de manera conjunta despr茅s d'haver-se sincronitzat executant Quorum Sensing. Amb el m猫tode que proposem, l'abast o rang de transmissi贸 augmenta proporcionalment al nombre d'emissors que se sincronitzen. A m茅s a m茅s, proposem un model anal铆tic de Quorum Sensing, el qual 茅s validat mitjan莽ant simulaci贸. Dit model permet calcular el nivell llindar d'activaci贸 del conjunt (que de fet determina l'amplificaci贸 resultant i el rang de transmissi贸 final) i el retard que el proc茅s de sincronitzaci贸 introdueix
Automata Modeling of Quorum Sensing for Nanocommunication Networks
Projecte final de carrera realitzat en col.laboraci贸 amb Broadband Wireless Networking Lab. Georgia Institute of Technology. AtlantaNanotechnology is enabling the development of devices in a scale ranging one to hundreds
of nanometers. Communication between these devices underlying in the nanoscale greatly
expands the possible applications, increasing the complexity and range of operation of the
system. Several options for nanocommunications have been discovered and studied, and
many of them take some natural mechanisms and processes as a model, or directly use
di erent elements from nature to serve its purposes. For instance, in molecular communications,
the information is encoded in tiny particles secreted by the emitter.
In this work, a special case of molecular communications is studied and modeled. Quorum
Sensing is a mechanism used by bacteria to sense their own population and coordinate
or synchronize their actions, through the emission and sensing of molecules called autoinducers.
The behavior of each bacterium involved featuring Quorum Sensing is modeled as an
individual nite state automaton, capturing its course of action. Later, the design of a novel
nanomachine that will include Quorum Sensing is presented, along with its applications.
Mainly, Quorum Sensing will serve to synchronize the processes of a group of nanodevices,
and this idea is developed to present \Collective Actuation Synchronization" and \Collective
Actuation after Localized Sensing" nanomachines. Finally, these con gurations are
implemented and simulated, and the results are later discussed