Received Signal Strength for Randomly Distributed Molecular Nanonodes

We consider nanonodes randomly distributed in a circular area and characterize the received signal strength when a pair of these nodes employ molecular communication. Two communication methods are investigated, namely free diffusion and diffusion with drift. Since the nodes are randomly distributed, the distance between them can be represented as a random variable, which results in a stochastic process representation of the received signal strength. We derive the probability density function of this process for both molecular communication methods. Specifically for the case of free diffusion we also derive the cumulative distribution function, which can be used to derive transmission success probabilities. The presented work constitutes a first step towards the characterization of the signal to noise ratio in the considered setting for a number of molecular communication methods.Comment: 6 pages, 6 figures, Nanocom 2017 conferenc

Engineering Yeast Cells to Facilitate Information Exchange

Although continuous advances in theoretical modelling of Molecular Communications (MC) are observed, there is still an insuperable gap between theory and experimental testbeds, especially at the microscale. In this paper, the development of the first testbed incorporating engineered yeast cells is reported. Different from the existing literature, eukaryotic yeast cells are considered for both the sender and the receiver, with {\alpha}-factor molecules facilitating the information transfer. The use of such cells is motivated mainly by the well understood biological mechanism of yeast mating, together with their genetic amenability. In addition, recent advances in yeast biosensing establish yeast as a suitable detector and a neat interface to in-body sensor networks. The system under consideration is presented first, and the mathematical models of the underlying biological processes leading to an end-to-end (E2E) system are given. The experimental setup is then described and used to obtain experimental results which validate the developed mathematical models. Beyond that, the ability of the system to effectively generate output pulses in response to repeated stimuli is demonstrated, reporting one event per two hours. However, fast RNA fluctuations indicate cell responses in less than three minutes, demonstrating the potential for much higher rates in the future.Comment: 18 pages, 9 figures (2 of which are not colored) all .png, recently accepted for publication at TMBM

Node criticality assessment in a blockchain network

Blockchain systems are being rapidly integrated in various technologies, with limited work on the effect of the underlying network topology on the blockchain performance. In this work, we investigate the significance of each network node on the overall blockchain performance. This is assessed by selecting critical nodes according to different criticality metrics, and investigating, using simulations, the degradation in performance incurred upon removing these nodes. The most critical nodes are the ones that incur the greatest degradation in performance. The considered performance metrics are the blockchain size and the packet drop rate. Criticality metrics such as Betweennes Centrality, Closeness Centrality and Degree Centrality are compared. It is found that the Sign Change Spectral Partitioning approach, enhanced with Blockchain Specific traffic flow information, is able to identify critical nodes better in the sense that higher degradation in performance is reported upon their removal

A lightweight blockchain based two factor authentication mechanism for LoRaWAN join procedure

Recently, there has been increasing interest in employing blockchain in different applications, other than crypto-currencies. Blockchains allow a peer to peer distributed network where different nodes communicate with each other, in a trustless manner. Long Range Wide Area Network (LoRaWAN) is an Internet of Things (IoT) technology, which enables long range communication. Although LoRaWAN networks are secure, the LoRaWAN join procedure is susceptible to replay and jamming attacks. Moreover, trust between network server and LoRa end device is the basic foundation of LoRaWAN network however, the centralized nature of network servers raise trust issues between network operators and customers. To solve this problem, we propose a lightweight two factor authentication mechanism for LoRaWAN join procedure, based on blockchain technology. The proposed blockchain based framework provides an extra layer of security for LoRaWAN join procedure and build trust among LoRaWAN network components. The proposed framework is validated using the Ethereum blockchain. The results demonstrate that the proposed framework provides efficient system performance in terms of throughput and latency. The proposed blockchain architecture is a cost effective solution, which can be utilized in the LoRaWAN network with few network servers and LoRa end device, having no strict requirement of throughput and latency

Energy management in harvesting enabled sensing nodes: prediction and control

Energy efficient transmission rate regulation of wireless sensing nodes, is a critical issue when operating in an energy harvesting (EH) enabled environment. In this work, we view the energy management problem as a queue control problem where the objective is to regulate transmission such that the energy level converges to a reference value. We employ a validated non-linear queuing model to derive two non-linear robust throughput controllers. A notable feature of the proposed scheme is its capability of predicting harvest-able energy. The predictions are generated using the proposed Accurate Solar Irradiance prediction Model (ASIM) whose effectiveness in generating accurate both long and short term predictions is demonstrated using real world data. The stability of the proposed controllers is established analytically and the effectiveness of the proposed strategies is demonstrated using simulations conducted on the Network Simulator (NS-3). The proposed policy is successful in guiding the energy level to the reference value, and outperforms the Throughput Optimal (TO) policy in terms of the throughput achieved

Intelligent Beam Steering for Wireless Communication Using Programmable Metasurfaces

Reconfigurable Intelligent Surfaces (RIS) are well established as a promising solution to the blockage problem in millimeter-wave (mm-wave) and terahertz (THz) communications, envisioned to serve demanding networking applications, such as 6G and vehicular. HyperSurfaces (HSF) is a revolutionary enabling technology for RIS, complementing Software Defined Metasurfaces (SDM) with an embedded network of controllers to enhance intelligence and autonomous operation in wireless networks. In this work, we consider feedback-based autonomous reconfiguration of the HSF controller states to establish a reliable communication channel between a transmitter and a receiver via programmable reflection on the HSF when Line-of-sight (LoS) between them is absent. The problem is to regulate the angle of reflection on the metasurface such that the power at the receiver is maximized. Extremum Seeking Control (ESC) is employed with the control signals generated mapped into appropriate metasurface coding signals which are communicated to the controllers via the embedded controller network (CN). This information dissemination process incurs delays which can compromise the stability of the feedback system and are thus accounted for in the performance evaluation. Extensive simulation results demonstrate the effectiveness of the proposed method to maximize the power at the receiver within a reasonable time even when the latter is mobile. The spatiotemporal nature of the traffic for different sampling periods is also characterized

On the use of programmable metasurfaces in vehicular networks

Metasurface-based intelligent reflecting surfaces constitute a revolutionary technology which can serve the purpose of alleviating the blockage problem in mmwave communication systems. In this work, we consider the hypersurface paradigm complementing the software defined metasurface with an embedded controller network in order to facilitate the dissemination of reconfiguration directives to unit cell controllers. For the first time, we describe the methodology with which to characterize the workload within this embedded network in the case of the metasurface tracking multiple users and we use a vehicular communications setting to showcase the methodology. Beyond that, we demonstrate use cases of the workload analysis. We show how the workload characterization can guide the design of information dissemination schemes achieving significant reduction in the network traffic. Moreover, we show how the workload, as a measure of the consumed power, can be used in designing energy efficient communication protocols through a multi-objective optimization problem maximizing the achieved utilization while at the same time minimizing the workload incurred.Peer ReviewedPostprint (author's final draft

A Congestion Control Algorithm for Max-Min Resource Allocation and Bounded Queue Sizes

This paper deals with the congestion control problem in computer networks which is viewed as a resource allocation problem constrained by the additional requirement that the queue sizes need to be bounded. We propose a distributed algorithm which converges to the max-min fair allocation of resources among the users of the network and at the same time ensures that the buffers are either empty or track a reference queue size. The problem is formulated mathematically and the proposed algorithm is shown analytically to fulfil the design objectives. The local asymptotic stability of the equilibrium point is established. The problem can be viewed as a hybrid system with changing affine dynamics in different regions of the state space. The transient performance of the proposed algorithm is evaluated through simulations using Matlab. The algorithm can form the basis for the development of an end-to-end communication protocol since it requires no maintenance of per flow states within the network