IoT and Smart Cities: Modelling and Experimentation

Internet of Things (IoT) is a recent paradigm that envisions a near future, in which the objects of everyday life will communicate with one another and with the users, becoming an integral part of the Internet. The application of the IoT paradigm to an urban context is of particular interest, as it responds to the need to adopt ICT solutions in the city management, thus realizing the Smart City concept. Creating IoT and Smart City platforms poses many issues and challenges. Building suitable solutions that guarantee an interoperability of platform nodes and easy access, requires appropriate tools and approaches that allow to timely understand the effectiveness of solutions. This thesis investigates the above mentioned issues through two methodological approaches: mathematical modelling and experimenta- tion. On one hand, a mathematical model for multi-hop networks based on semi- Markov chains is presented, allowing to properly capture the behaviour of each node in the network while accounting for the dependencies among all links. On the other hand, a methodology for spatial downscaling of testbeds is proposed, implemented, and then exploited for experimental performance evaluation of proprietary but also standardised protocol solutions, considering smart lighting and smart building scenarios. The proposed downscaling procedure allows to create an indoor well-accessible testbed, such that experimentation conditions and performance on this testbed closely match the typical operating conditions and performance where the final solutions are expected to be deployed

D22.1 Definition of EuWIn@CNIT/Bologna testbed interfaces and preliminary plan of activities

Preprin

Neighbor Discovery in Wireless Networks: A Graph-based Analysis and Optimization

The neighbor discovery (ND) procedure is typically performed during the network setup and allows nodes to learn about the existence of neighbors, exploiting the transmission of broadcast messages. Battery powered nodes impose many constraints on the ND protocol, such as low latency and energy efficiency. This calls for the deployment of dedicated and efficient ND protocols allowing nodes to be idle and save energy. We propose and analyze a new ND protocol, named collision resolution birthday protocol (CRBP), that drastically improves the performance of the birthday protocol (BP) making the use of multiple transmitted packets per node and successive interference cancellation (SIC). Via a bipartite graph analysis, we optimize the number of transmitted packets per node in order to maximize the discovery rate, under the asymptotically large frame assumption. Numerical simulations are performed for evaluating the goodness of the optimization also for finite frame durations

Modeling multi-hop CSMA-based networks through Semi-Markov chains

In this paper we address multi-hop Carrier Sense Multiple Access (CSMA)-based networks and we propose a novel approach based on a semi-Markov chain analysis, decoupling node and network levels. We model node states through a Semi-Markov Process and, on the other hand, we define a finite state transition diagram to describe the network states. The latter is used to derive the parameters included in the Semi-Markov Chain that depend on the network status, as for example, the probability of finding the channel busy. In particular, we consider a multi-hop wireless network, where nodes are deployed over a straight line. Each node sends its data to the next node in the line, to reach the destination located at the end. Nodes use a CSMA-based protocol, where priority in the access to the channel is given to nodes closer to the destination. We mathematically derive the network performance, in terms of throughput and energy consumption. The model is validated through comparison with simulations

Experimental characterization of Low Power Listening in BAN

This paper presents an implementation of a Low Power Listening-based (LPL) Medium Access Control (MAC) protocol on a platform for Body Area Network (BAN) applications. LPL exploits the transmission of a burst of short packets, called preambles, to synchronize the transmitter and the receiver. In this way, devices are able to spend most of the time in sleeping mode, providing longer lifetime and energy saving. Experiments on the field have been conducted by considering different scenarios and results, in terms of average energy consumed per packet, packet loss rate and average delay, have been investigated. Conclusions regarding the proper parameters setting depending on the application requirements were derived. This work has been performed in the framework of the FP7 Integrated Project, WiserBAN

Low Power Listening in BAN: Experimental Characterisation

This paper presents an implementation of a Low Power Listening-based (LPL) Medium Access Control (MAC) protocol on a platform for Body Area Network (BAN) applications. LPL exploits the transmission of a burst of short packets, called preambles, to synchronize the transmitter and the receiver. In this way, devices are able to spend most of the time in sleeping mode, providing longer lifetime and energy saving. Experiments on the field have been conducted by considering different scenarios and results, in terms of average energy consumed per packet transmitted/received, packet loss rate, average delay and network throughput, have been investigated. Conclusions regarding the proper parameters setting depending on the application requirements were derived. This work has been performed in the framework of the FP7 Integrated Project, WiserBAN. Copyright \ua9 2014, IGI Global

The EuWin Platform: From a Down-Scaled Testbed to the Real Deployment

This paper proposes an empirically-based methodology that can be used for spatial down-scaling of wireless sensor networks (WSNs). WSNs are often deployed in environments not easily accessible, highly unpredictable and where running experiments is generally very expensive and time consuming. The latter calls for the need to develop down-scaled testbeds, deployed in a controlled environment, where tests can be conducted under predictable and replicable conditions. In this paper we present a methodology to realise the down-scaling of a real testbed on a testbed developed at the University in the framework of the Network of Excellence, NEWCOM#, with reference to EuWIn (the "European Laboratory of Wireless Communications for the Future Internet"). The real testbed we refer to is composed of 24 devices, deployed on the lamp posts of the small town of Casalgrande (Italy), and running a smart city application. The proposed procedure for the down-scaling is implemented and the results achieved on the real testbed and on the down-scaled testbed are compared. The comparison is performed in terms of network topologies and average number of hops necessary to reach the gateway. Results demonstrate the utility of EuWIn for down-scaling purposes and the efficacy of the proposed methodology

From a Real Deployment to a Downscaled Testbed: A Methodological Approach

This paper proposes a novel methodology for the spatial downscaling of real-world deployments of wireless networks, running protocols, and/or applications for the Internet of Things (IoT). These networks are often deployed in environments not easily accessible and highly unpredictable, where doing experiments is very expensive and time consuming. The latter calls for the need to develop downscaled testbeds, deployed in controlled environments, where tests can be conducted under predictable conditions. This paper presents a methodology to realize the downscaling of a real deployment on an experimental platform, called controllable testbed that has a much larger number of nodes with respect to the real one. The downscaling procedure proposed is based on the identification of the most appropriate subset of nodes of the controllable testbed, to be used to reproduce the channel gains between each node pair in the real world. The latter, in fact, results in obtaining the same network topologies, bringing to the same performance on average, when the same protocol stack and software are run. After the description of the procedure, an example of its implementation is provided. Comparison of results, in terms of packet loss rate (PLR), network throughput, and topologies achieved on the downscaled testbed and on the real-world deployment, is given; results show a very good fit and demonstrate the efficacy of the proposed methodology