CoSIP: a constrained session initiation protocol for the Internet of Things

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S. Cirani, M. Picone, and L. Veltri, CoSIP: a constrained session initiation protocol for the Internet of ThingsEuropean Conference on Service-Oriented and Cloud Computing, (ESOCC 2013), Workshop Cloud for IoT (CLIoT 2013), Malaga, Spain, September 2013, 15 pages.
Available online.            DOI: 10.1007/978-3-642-45364-9_2

Abstract: The Internet of Things (IoT) refers to the interconnection of billions of constrained devices, denoted as “smart objects” (SO), in an Internet-like structure. SOs typically feature limited capabilities in terms of computation and memory and operate in constrained environments, such low-power lossy networks. As IP has been foreseen as the standard for smart-object communication, an effort to bring IP connectivity to SOs and define suitable communication protocols (i.e. CoAP) is being carried out within standardization organisms, such as IETF. In this paper, we propose a constrained version of the Session Initiation Protocol (SIP), named “CoSIP”, whose intent is to allow constrained devices to instantiate communication sessions in a lightweight and standard fashion. Session instantiation can include a negotiation phase of some parameters which will be used for all subsequent communication. CoSIP can be adopted in several application scenarios, such as service discovery and publish/subscribe applications, which are detailed. An evaluation of the proposed protocol is also presented, based on a Java implementation of CoSIP, to show the benefits that its adoption can bring about, in terms of compression rate with the existing SIP protocol and message overhead compared with the use of CoAP.

Design and evaluation of a delay-efficient RPL routing metric

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P. Gonizzi, R. Monica, and G. Ferrari, Design and evaluation of a delay-efficient RPL routing metric9th International Wireless Communications & Mobile Computing Conference, (IWCMC 2013), Cagliari-Sardinia, Italy, July 2013, pp. 1573-1577.
DOI: 10.1109/IWCMC.2013.6583790. Available online

Abstract: The Routing Protocol for Low power and Lossy Networks (RPL) is the IETF standard for IPv6 routing in lowpower wireless sensor networks. It is a distance vector routing protocol that builds a Destination Oriented Directed Acyclic Graph (DODAG) rooted towards one sink (the DAG root), using an objective function and a set of metrics/constraints to compute the best path. In this paper, we propose a routing metric which minimizes the delay towards the DAG root, assuming that nodes run with very low duty cycles (e.g., under 1%) at the MAC layer. We evaluate the proposed routing metric with the Contiki operating system and compare its performance with that of the Expected Transmission Count (ETX) metric. Moreover, we propose some extensions to the ContikiMAC radio duty cycling protocol to support different sleeping periods of the nodes.

Batch-based group key management with shared key derivation in the Internet of Things

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L. Veltri, S. Cirani, G. Ferrari, and S. Busanelli, Batch-based group key management with shared key derivation in the Internet of Things9th International Wireless Communications & Mobile Computing Conference, (IWCMC 2013), Cagliari-Sardinia, Italy, July 2013, pp. 1688-1693.
DOI: 10.1109/IWCMC.2013.6583810. Available online

Abstract: Many applications for ad-hoc networks are based on a multicast communication paradigm, where a single source sends common data to many receivers. In these contexts, it is possible to efficiently secure the multicast communications by leveraging on a common secret key, denoted as “group key”, shared by multiple users. In this paper, we propose a novel centralized approach that efficiently addresses the problem of deriving and managing a group key in generic ad-hoc networks and Internet of Things (IoT) scenarios, reducing the computation overhead due to group membership changes caused by user’s joins and leaves. In particular, the proposed method takes advantage of the assumption of two possible leave strategies: (i) at a pre-determined time interval selected when the member joins the group or (ii) at any unpredictable time interval, as in the case of membership revocation.

A novel batch-based group key management protocol applied to the Internet of Things

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L. Veltri, S. Cirani, S. Busanelli, and G. Ferrari, A novel batch-based group key management protocol applied to the Internet of ThingsAd Hoc Networks, vol. 11, no. 8, pp. 2724-2737, November 2013.
DOI: 10.1016/j.adhoc.2013.05.009. Available online

Abstract: Many applications for ad hoc networks are based on a point-to-multipoint (multicast) communication paradigm, where a single source sends common data to many receivers, or, inversely, on a multipoint-to-point communication paradigm, where multiple sources send data to a single receiver. In such scenarios, communication can be secured by adopting a common secret key, denoted as ‘‘group key’’, shared by multiple communication endpoints. In this work, we propose a novel centralized approach to efficiently distribute and manage a group key in generic ad hoc networks and Internet of Things, while reducing the computational overhead and network traffic due to group membership changes caused by users’ joins and leaves. In particular, the proposed protocol takes advantage of two possible leave strategies: (i) at a pre-determined time selected when the user joins the group or (ii) at an unpredictable time, as in the case of membership revocation. The proposed protocol is applied to two following relevant scenarios: (i) secure data aggregation in Internet of Things (IoT) and (ii) Vehicle-to-Vehicle (V2V) communications in Vehicular Ad hoc Networks (VANETs).

Summer School on Internet of Things and Smart Cities 2013

CALIPSO announces the Ph.D. School on Internet of Things and Smart Cities 2013, which will be held in Lerici (La Spezia), 16-21 September 2013. Register here.

The aim of Ph.D. School is to address young researchers to the forefront of research  activity on Smart Cities & Internet of Things, by presenting state-of-the-art research together with the current and future challenges in building smart cities in an efficient and sustainable way, in order to provide a thorough overview of the main topics about Smart Cities and IoT and their envisioned integration. International speakers from academia and industry will give lectures tailoring their research field for an interdisciplinary audience. A dedicated discussion panel will focus on the interaction and the collaboration between academia and industry in order to depict the future vision of Smart Cities and IoT. Participants will also have the opportunity to present their research activities during a dedicated session. The school will allow participants to be exposed to cutting edge results in one of the most challenging research area, while at the same time enjoying the relaxing atmosphere of one of the most beautiful italian locations.

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Investigating the resilience of unstructured supernode networks

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M. Amoretti and G. Ferrari, Investigating the resilience of unstructured supernode networksIEEE Communications Letters, 3. vol. 17, no. 6, pp. 1272-1275, June 2013.
DOI: 10.1109/LCOMM.2013.043013.130305. Available online

Abstract: In this letter, we present a novel analytical framework to analyze the resilience of Unstructured Supernode Networks (USNs), where a “leaf” node can be promoted, after  a fixed time interval, to the role of “supernode,” with nonpreferential attachment to a given number of existing supernodes.  In particular, relying on an Absorbing Markov Chain (AMC)-based model of a supernode behavior, we derive an efficient  approximation of the node degree distribution of an USN. This model also allows to estimate a supernode’s probability of isolation. The proposed analytical framework is validated by simulation results.

Distributed Storage Schemes for IoT Observation Systems at Large Scale

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P. Gonizzi, G. Ferrari, V. Gay, and J. Leguay, Data dissemination scheme for distributed storage for IoT observation systems at large scale, Information Fusion, Special Issue on “Collaborative Wireless Sensor Networks: Architectures, Algorithms and Applications”, April 2013.
DOI: 10.1016/j.inffus.2013.04.003. Available online

Abstract: In the emerging field of the Internet of Things (IoT), Wireless Sensor Networks (WSNs) have a key role to play in sensing and collecting measures on the surrounding environment. In the deployment of large scale observation systems in remote areas, when there is not a permanent connection with the Internet, WSNs are calling for replication and distributed storage techniques that increase the amount of data stored within the WSN and reduce the probability of data loss. Unlike conventional network data storage, WSN-based distributed storage is constrained by the limited resources of the sensors. In this paper, we propose a low-complexity distributed data replication mechanism to increase the resilience of WSN-based distributed storage at large scale. In particular, we propose a simple, yet accurate, analytical modeling framework and an extensive simulation campaign, which complement experimental results on the SensLab testbed. The impact of several key parameters on the system performance is investigated.

Enforcing Security Mechanisms in the IP-based Internet of Things: an Algorithmic Overview

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S. Cirani, G. Ferrari, and L. Veltri, Enforcing security mechanisms in the IP-based Internet of Things: an algorithmic overview, Algorithms, Special Issue on “Sensor Network”, vol. 6, no. 2, pp. 197-226, 2013.
DOI: 10.3390/a6020197. Available online

Abstract: : The Internet of Things (IoT) refers to the Internet-like structure of billions of interconnected constrained devices, denoted as “smart objects”. Smart objects have limited capabilities, in terms of computational power and memory, and might be battery-powered devices, thus raising the need to adopt particularly energy efficient technologies. Among the most notable challenges that building interconnected smart objects brings about, there are standardization and interoperability. The use of IP has been foreseen as the standard for interoperability for smart objects. As billions of smart objects are expected to come to life and IPv4 addresses have eventually reached depletion, IPv6 has been identified as a candidate for smart-object communication. The deployment of the IoT raises many security issues coming from (i) the very nature of smart objects, e.g., the adoption of lightweight cryptographic algorithms, in terms of processing and memory requirements; and (ii) the use of standard protocols, e.g., the need to minimize the amount of data exchanged between nodes. This paper provides a detailed overview of the security challenges related to the deployment of smart objects. Security protocols at network, transport, and application layers are discussed, together with lightweight cryptographic algorithms proposed to be used instead of conventional and demanding ones, in terms of computational resources. Security aspects, such as key distribution and security bootstrapping, and application scenarios, such as secure data aggregation and service authorization, are also discussed.

Clustered IEEE 802.15.4 sensor networks with data aggregation: energy consumption and probability of error

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M. Martalò, C. Buratti, G. Ferrari, and R. Verdone. Clustered IEEE 802.15.4 sensor networks with data aggregation: energy consumption and probability of error. IEEE Wireless Communications Letters, vol. 2, no. 1, pp. 70-73, February 2013.
DOI: 10.1109/WCL.2012.112012.120644. Available online

Abstract: In this paper, we analyze an IEEE 802.15.4-compliant wireless sensor network, organized in clusters with fusion centers (FCs) acting as cluster heads. Sensors observe the same common binary phenomenon, decide on its status, and send their decisions to the FCs, which perform a majority fusion. FCs’ decisions are then sent to an access point, where a final estimate is obtained. Data aggregation (DA) over consecutive observations can be also performed at sensors, with the aim of reducing the number of sensors simultaneously competing for the channel, while increasing the packet size. A novel mathematical framework for deriving the energy consumption in IEEE 802.15.4 networks is also proposed. The performance is evaluated in terms of energy consumption and probability of decision error, jointly accounting for decentralized detection, medium access, and DA.

Redundant distributed data storage: experimentation with the SensLab testbed

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P. Gonizzi, G. Ferrari, V. Gay, and J. Leguay. Redundant distributed data storage: experimentation with the SensLab testbed1st International Conference on Sensor Networks (SENSORNETS 2012), Rome, Italy, February 2012, pp. 15-23.
DOI: 10.5220/0003803900150023. Available online       Best paper award.

Abstract: Wireless sensor network (WSN)-based applications typically require to store data in the network. For instance, in the surveillance of isolated areas, if no sink nodes are present, WSNs may archive observation data that are periodically retrieved by an external agent. In contrast to conventional network data storage, storing data in WSNs is challenging because of the limited power, memory, and communication bandwidth of WSNs. In our study, we review the state-of-art techniques for data replication and storage in WSNs, and we propose a lowcomplexity distributed data replication mechanism to increase the resilience of WSN storage capacity against node failure and local memory shortage. We evaluate our approach through experimental results collected on the SensLab large-scale real testbed. In particular, we show how the performance is affected by changing the configuration of several key system parameters, such as (i) the transmission power of the nodes; (ii) the control message overhead; (iii) the number of deployed nodes; and (iv) the redundancy. To the best of our knowledge, this is one of the first works presenting experimental results at a really large-scale on SensLab.