Rasmus Hjorth Nielsen

The evolution of M2M into IoT

Machine-to-Machine (M2M) communication has attracted considerable attention in research communities and has also started to gain momentum from a commercial perspective where operators are starting to offer services within the domains of fleet management, logistics, home automation, etc. At the same time, the more loosely defined, but broader domain of Internet of Things (IoT) is picking up as what many are seeing as an evolution of M2M. This paper investigates the fundamental differences of M2M and IoT by starting out with surveying some of the drivers and moving into an analysis of M2M of today from a technological and business perspective. The challenges in moving into IoT are investigated with emphasize on networking and computing.

Harvesting energy from vibrations of the underlying structure

The use of wireless sensors for structural health monitoring offers several advantages such as small size, easy installation and minimal intervention on existing structures. However the most significant concern about such wireless sensors is the lifetime of the system, which depends heavily on the type of power supply. No matter how energy efficient the operation of a battery operated sensor is, the energy of the battery will be exhausted at some point. In order to achieve a virtually unlimited lifetime, the sensor node should be able to recharge its battery in an easy way. Energy harvesting emerges as a technique that can harvest energy from the surrounding environment. Among all possible energy harvesting solutions, kinetic energy harvesting seems to be the most convenient, especially for sensors placed on structures that experience regular vibrations. Such micro-vibrations can be harmful to the long-term structural health of a building or bridge, but at the same time they can be exploited as a power source to power the wireless sensors that are monitoring this structural health. This paper presents a new energy harvesting method based on a vibration driven electromagnetic harvester. By using an improved Maximum Power Point Tracking technique on the conversion circuit, the proposed method is shown to maximize the conversion coefficient from kinetic energy to applicable electrical energy.

Efficient admission control for next generation cellular networks

This paper proposes a novel efficient admission control (AC) algorithm, which guarantees quality of service (QoS) for new users while maintaining QoS for existing users and also increases the number of users admitted in to the system. To guarantee the QoS, a Markov based modeling of the queue in the MAC layer is done by considering the effects of adaptive modulation and coding (AMC) in the physical layer. Using the Markov model, the number of resources required by the new user is predicted by taking the QoS requirements of the user application and channel parameters into consideration. The proposed AC algorithm is based on mean resource calculation, where the mean number of resources used by the existing users is calculated taking in to account the buffer conditions of users. The efficiency of AC algorithm is measured w.r.t number of users admitted in the system. The AC algorithm is verified on a Long Term Evolution (LTE) system and simulations show a 10% increase in the number of users and a decrease in the dropping probability.

Data collection using miniature aerial vehicles in wireless sensor networks

Energy constraints of sensor nodes in wireless sensor networks (WSNs) is a major challenge and minimising the overall data transmitted across a network using data aggregation, distributed source coding, and compressive sensing have been proposed as mechanisms for energy saving. Similarly, use of mobile nodes capable of relocating within the network has been widely explored for energy saving. In this study, the authors propose a novel method for using miniature aerial vehicles for data collection instead of actively sensing from a deployed network. The proposed mechanism is referred as data collection fly (DCFly). It is suitable for data collection from WSNs deployed in harsh- undulating terrain with the base station located far from the sensing region. The DCFly is compared with data collection based on multi-hop data aggregation and data collection with mobile sinks. The numerical results justify that the proposed data collection mechanism is effective and efficient for use in WSNs. 1 Introduction Wireless sensor networks (WSNs) are deployed in an area to be monitored, referred to in this paper as the sensing region, for diverse applications such as habitat and environmental monitoring, battlefield surveillance, and industrial monitoring. Using active node mobility in the network, overall communication in the network can be reduced and specifically nodes close to the base station (BS) could be prevented from draining out. Various utilities that are possible using active node mobility in the network are: mobile relay, mobile data mule, and mobile BS. Alternatively, in-network data processing mechanisms such as data aggregation, network coding, and compressive sensing could be utilised for minimising the overall communication of the network. These two approaches, that is, node mobility, and in-network processing have been extensively explored individually and independently. This paper presents a mechanism for data collection using a data collection fly (DCFly). The DCFly would aerially collect data from the network. This is the first work that explores the potential of using miniature aerial vehicles (MAVs) for collecting data, collectively involving node mobility and in-network data processing. The underlying framework adopted in this paper has been presented in our preliminary work (1). The remaining paper has been structured as follows: in Section 2, previous work relating to node mobility and in-networking data processing has been presented. Section 3 provides an insight into factors governing optimal number of cluster heads (CHs) and inter-relation with position of BS, data collection operation by the DCFly; these aspects influence the network architecture. The factors governing the DCFlys possible use in the sensing region and the network operational conditions considered for evaluation are presented in Section 4. The DCFlys governing factors formulated as an optimisation problem to determine the feasible operational utility are presented in Section 5. The optimum number of clusters that can be covered by a single DCFly are presented in Section 6, along with the comparative evaluation of the proposed DCFly with a multi-hop data aggregation mechanism (referred as DA mechanism). The DCFly-based data collection is also compared with data collection from the network relying on mobile elements (MEs) in Sections 6.1 and 6.2. Finally, this paper is concluded in Section 7. 2 Related work As stated earlier, the methods for minimising the energy consumption in the network can be broadly categorised into node mobility and in-network data processing-based mechanisms.

Wildlife conservation and rail track monitoring using wireless sensor networks

In this paper we put forward an approach, first of its kind, to collectively address conservation of elephants by preventing their death being overrun by trains and monitoring the integrity of the rail track. It utilizes a unique method for deterring the elephants using infrasonic sound from crossing the rail track. For obtaining this output the sensing devices are placed in proximity areas of the rail track using a novel passive node mobility mechanism. These devices act as an input to the actual sensing nodes, that would emit the infrasonic sound. Utilizing a novel two - cycle communication and sensing check the integrity of the rail track is evaluated and the result is informed to the regional base station (RBS). The proposed approach offers a promising solution to the two issues, subject to field evaluation and validation.

GCF: Green Conflict Free TDMA scheduling for wireless sensor network

The last few years have seen the promising growth in the application of wireless sensor networks (WSNs). The contribution of this paper is on a cluster-based time division multiple access (TDMA) scheduling algorithm to improve the performance of WSN applications in terms of energy efficiency, delay, throughput and scalability. Cluster-based scheduling improves the scalability by stabilizing the topology and it also improves the delay by increasing the reuse of slots. The paper proposes the Green Conflict Free (GCF) algorithm for finding a conflict free schedule across three-hop neighbours for inter- and intra-cluster communication. The algorithm is applied to a multi-hop cluster and uses a conflict graph to find the conflict free schedule. It helps to reduce the number of conflicts. Compared to state-of-the-art solutions, the algorithm shows better energy efficiency, average delay, scalability and better slot sharing through a reduced number of conflicts.

The WKB approximation for analysis of wave propagation in curved rods of slowly varying diameter

The Wentzel–Kramers–Brillouin (WKB) approximation is applied for asymptotic analysis of time-harmonic dynamics of corrugated elastic rods. A hierarchy of three models, namely, the Rayleigh and Timoshenko models of a straight beam and the Timoshenko model of a curved rod is considered. In the latter two cases, the WKB approximation is applied for solving systems of two and three linear differential equations with varying coefficients, whereas the former case is concerned with a single equation of the same type. For each model, explicit formulations of wavenumbers and amplitudes are given. The equivalence between the formal derivation of the amplitude and the conservation of energy flux is demonstrated. A criterion of the validity range of the WKB approximation is proposed and its applicability is proved by inspection of eigenfrequencies of beams of finite length with clamped–clamped and clamped-free boundary conditions. It is shown that there is an appreciable overlap between the validity ranges of the Timoshenko beam/rod models and the WKB approximation.

A Framework for Planning a Unified Wired and Wireless ICT Infrastructure

The increase in the use of information and communication technology (ICT) has pushed the existing access networks to their limits. Whole new access networks are currently being deployed and are expected to fully support the already started synergy of services converging on to one network. Through a brief survey of synergy and technology trends, it is concluded that a future network will use wired and wireless as complementary technologies. In this context the paper proposes a framework for planning of unified wired and wireless ICT infrastructures. The framework includes different input parameters of relevance for the planning and implementation, which also include a step-wise implementation plan. Planning methods for wired and wireless planning is presented and a simplified large-scale case study is conducted to verify and illustrate the use of the framework. The framework is concluded to be useful and the discussion lists some areas for further consideration.

Comparison of Cost for Different Coverage Scenarios between Copper and Fiber Access Networks

As the demand for bandwidth in broadband Internet connections to private households are increasing, the current copper network in Denmark is facing a considerable upgrade to meet the governments goal of equal access to everyone. In this paper an analysis is presented concerning the coverages of households for a variety of xDSL technologies. A cost estimation has been made when expanding the current copper infrastructure to provide VDSL connections to all households in a municipality in Denmark. This is compared to the price of providing fiber to the home (FTTH) in the same area. Furthermore, the prices of providing FTTH to the coverage areas of those comparable with VDSL are estimated

On radio over fiber for heterogeneous wireless networks

The paper provides an overview of the Radio of Fiber (RoF) technology and its potential use in heterogeneous wireless networks. Wireless communications have seen a huge growth in the last decade. It has been estimated that five in every six people in the entire world will have a mobile phone in 2010. The vast growing use of Internet on the mobile devices has also been increased significantly. In order to provide a broadband access for mobile communications, a new wireless infrastructure (Fiber Optic Networks for Distributed, Extendible Heterogeneous Radio Architectures and Service Provisioning - FUTON) based on RoF technology has been introduced. The project adopts centralized processing of radio signals for number of wireless base stations can enhance the network performance in terms of bandwidth, and QoS parameters. The simplified Remote Access Units (RAU) are expected to not only increase the performance but also help to reduce the overall coast of the infrastructure.