A practical framework for data collection in wireless sensor networks

Optimizing energy consumption for extending the lifetime in wireless sensor networks is of dominant importance. Groups of autonomous robots and unmanned aerial vehicles (UAVs) acting as mobile data collectors are utilized to minimize the energy expenditure of the sensor nodes by approaching the sensors and collecting their buffers via single hop communication, rather than using multihop routing to forward the buffers to the base station. This paper models the sensor network and the mobile collectors as a system-of-systems, and defines all levels and types of interactions. A practical framework that facilitates deploying heterogeneous mobiles without prior knowledge about the sensor network is presented. Realizing the framework is done through simulation experiments and tested against several performance metrics.<br /

Adaptive online deployment for resource constrained mobile smart clients

Nowadays mobile devices are more and more used as a platform for applications. Contrary to prior generation handheld devices configured with a predefined set of applications, today leading edge devices provide a platform for flexible and customized application deployment. However, these applications have to deal with the limitations (e.g. CPU speed, memory) of these mobile devices and thus cannot handle complex tasks. In order to cope with the handheld limitations and the ever changing device context (e.g. network connections, remaining battery time, etc.) we present a middleware solution that dynamically offloads parts of the software to the most appropriate server. Without a priori knowledge of the application, the optimal deployment is calculated, that lowers the cpu usage at the mobile client, whilst keeping the used bandwidth minimal. The information needed to calculate this optimum is gathered on the fly from runtime information. Experimental results show that the proposed solution enables effective execution of complex applications in a constrained environment. Moreover, we demonstrate that the overhead from the middleware components is below 2%

Load balancing in downlink LTE self-optimizing networks

In this paper we present system level simulation results of a self-optimizing load balancing algorithm in a long-term-evolution (LTE) mobile communication system. Based on previous work, we evaluate the network performance of this algorithm that requires the load of a cell as input and controls the handover parameters. We compare the results for different simulation setups: for a basic, regular network setup, a non-regular grid with different cell sizes and also for a realistic scenario based on measurements and realistic traffic setup

Optimizing Sustainable Transit Bus Networks in Smart Cities

Urban mobility has been facing several challenges in the recent years due to the increasing populations and private vehicles ownership, which led to several negative environmental and social impacts in big cities. In this dissertation, we investigate how decision support systems can enhance the role of transit bus networks in the transition to more sustainable and convenient urban mobility

Analysis and performance improvement of consumer-grade millimeter wave wireless networks

Millimeter-wave (mmWave) networks are one of the main key components in next cellular and WLANs (Wireless Local Area Networks). mmWave networks are capable of providing multi gigabit-per-second rates with very directional low-interference and high spatial reuse links. In 2013, the first 60 GHz wireless solution for WLAN appeared in the market. These were wireless docking stations under theWiGig protocol. Today, in 2019, 60 GHz communications have gained importance with the IEEE 802.11ad amendment with different products on the market, including routers, laptops and wireless Ethernet solutions. More importantly, mmWave networks are going to be used in next generation cellular networks, where smartphones will be using the 28 GHz band. For backbone links, 60 GHz communications have been proposed due to its higher directionality and unlicensed use. This thesis fits in this frame of constant development of themmWave bands to meet the needs of latency and throughput that will be necessary to support future communications. In this thesis, we first characterize the cost-effective design of COTS (commercial off-the-shelf) 60 GHz devices and later we improve their two main weaknesses, which are their low link distance and their non-ideal spatial reuse. It is critical to take into consideration the cost-effective design of COTS devices when designing networking mechanisms. This is why in this thesis we do the first-of-its-kind COTS analysis of 60 GHz devices, studying the D5000 WiGig Docking station and the TP-Link Talon IEEE 802.11ad router. We include static measurements such as the synthesized beam patterns of these devices or an analysis of the area-wide coverage that these devices can fulfill. We perform a spatial reuse analysis and study the performance of these devices under user mobility, showing how robust the link can be under user movement. We also study the feasibility of having flying mmWave links. We mount a 60 GHz COTS device into a drone and perform different measurement campaigns. In this first analysis, we see that these 60 GHz devices have a large performance gap for the achieved communication range as well as a very low spatial reuse. However, they are still suitable for low density WLANs and for next generation aerial micro cell stations. Seeing that these COTS devices are not as directional as literature suggests, we analyze how channels are not as frequency stable as expected due to the large amount of reflected signals. Ideally, frequency selective techniques could be used in these frequency selective channels in order to enlarge the range of these 60 GHz devices. To validate this, we measure real-world 60 GHz indoor channels with a bandwidth of 2 GHz and study their behavior with respect to techniques such as bitloading, subcarrier switch-off, and waterfilling. To this end, we consider a Orthogonal Frequency-Division Multiplexing (OFDM) channel as defined in the IEEE 802.11ad standard and show that in point of fact, these techniques are highly beneficial in mmWave networks allowing for a range extension of up to 50%, equivalent to power savings of up to 7 dB. In order to increase the very limited spatial reuse of these wireless networks, we propose a centralized system that allows the network to carry out the beam training process not only to maximize power but also taking into account other stations in order to minimize interference. This system is designed to work with unmodified clients. We implement and validate our system on commercial off-the-shelf IEEE 802.11ad hardware, achieving an average throughput gain of 24.67% for TCP traffic, and up to a twofold throughput gain in specific cases.Programa de Doctorado en Multimedia y Comunicaciones por la Universidad Carlos III de Madrid y la Universidad Rey Juan CarlosPresidente: Andrés García Saavedra.- Secretario: Matilde Pilar Sánchez Fernández.- Vocal: Ljiljana Simi

Distributed Hybrid Simulation of the Internet of Things and Smart Territories

This paper deals with the use of hybrid simulation to build and compose heterogeneous simulation scenarios that can be proficiently exploited to model and represent the Internet of Things (IoT). Hybrid simulation is a methodology that combines multiple modalities of modeling/simulation. Complex scenarios are decomposed into simpler ones, each one being simulated through a specific simulation strategy. All these simulation building blocks are then synchronized and coordinated. This simulation methodology is an ideal one to represent IoT setups, which are usually very demanding, due to the heterogeneity of possible scenarios arising from the massive deployment of an enormous amount of sensors and devices. We present a use case concerned with the distributed simulation of smart territories, a novel view of decentralized geographical spaces that, thanks to the use of IoT, builds ICT services to manage resources in a way that is sustainable and not harmful to the environment. Three different simulation models are combined together, namely, an adaptive agent-based parallel and distributed simulator, an OMNeT++ based discrete event simulator and a script-language simulator based on MATLAB. Results from a performance analysis confirm the viability of using hybrid simulation to model complex IoT scenarios.Comment: arXiv admin note: substantial text overlap with arXiv:1605.0487

Powering a Biosensor Using Wearable Thermoelectric Technology

Wearable medical devices such as insulin pumps, glucose monitors, hearing aids, and electrocardiograms provide necessary medical aid and monitoring to millions of users worldwide. These battery powered devices require battery replacement and frequent charging that reduces the freedom and peace of mind of users. Additionally, the significant portion of the world without access to electricity is unable to use these medical devices as they have no means to power them constantly. Wearable thermoelectric power generation aims to charge these medical device batteries without a need for grid power. Our team has developing a wristband prototype that uses body heat, ambient air, and heat sinks to create a temperature difference across thermoelectric modules thus generating ultra-low voltage electrical power. A boost converter is implemented to boost this voltage to the level required by medical device batteries. Our goal was to use this generated power to charge medical device batteries off-the-grid, increasing medical device user freedom and allowing medical device access to those without electricity. We successfully constructed a wearable prototype that generates the voltage required by an electrocardiogram battery; however, further thermoelectric module and heat dissipation optimization is necessary to generate sufficient current to charge the battery