Erkki Harjula

CloudThings: A common architecture for integrating the Internet of Things with Cloud Computing

The Internet of Things presents the user with a novel means of communicating with the Web world through ubiquitous object-enabled networks. Cloud Computing enables a convenient, on demand and scalable network access to a shared pool of configurable computing resources. This paper mainly focuses on a common approach to integrate the Internet of Things (IoT) and Cloud Computing under the name of CloudThings architecture. We review the state of the art for integrating Cloud Computing and the Internet of Things. We examine an IoT-enabled smart home scenario to analyze the IoT application requirements. We also propose the CloudThings architecture, a Cloud-based Internet of Things platform which accommodates CloudThings IaaS, PaaS, and SaaS for accelerating IoT application, development, and management. Moreover, we present our progress in developing the CloudThings architecture, followed by a conclusion.

Plug-and-play application platform: towards mobile peer-to-peer

While peer-to-peer (P2P) has emerged as a new hot communication concept among the Internet users, mobile usage of P2P applications is still taking its first steps. This article first elaborates the evolutionary process that P2P architectures are going through. Challenges and requirements for mobile P2P are then identified, followed by a definition of a novel Plug-and-Play Application Platform (PnPAP). This platform enables dynamic selections between diverse P2P and session management protocols while preserving the best available network connectivity through Holistic Connectivity (HCon) management. On-the-fly reconfiguration and run-time parameter optimization can be done with a lightweight interpretable state machine. The concept enables flexible and seamless communications for mobile devices in P2P networks.

Performance evaluation of a Kademlia-based communication-oriented P2P system under churn

The phenomenon of churn has a significant effect on the performance of Peer-to-Peer (P2P) networks, especially in mobile environments that are characterized by intermittent connections and unguaranteed network bandwidths. A number of proposals have been put forward to deal with this problem; however, we have so far not seen any thorough analysis to guide the optimal design choices and parameter configurations for structured P2P networks. In this article, we present a performance evaluation of a structured communication-oriented P2P system in the presence of churn. The evaluation is conducted using both simulation models and a real-life prototype implementation. In both evaluation environments, we utilize Kademlia with some modifications as the underlying distributed hash table (DHT) algorithm, and Peer-to-Peer Protocol (P2PP) as the signaling protocol. The results from the simulation models created using Nethawk EAST (a telecommunication simulator software) suggest that, in most situations, a lookup parallelism degree of 3 and resource replication degree of 3 are enough for guaranteeing a high resource lookup success ratio. We also notice that, with the parallel lookup mechanism, a good success ratio is achieved even without the KeepAlive traffic that is used for detecting the aliveness of nodes. A prototype system that works in mobile environment is implemented to evaluate the feasibility of mobile nodes acting as full-fledged peers. The measurements made using the prototype show that, from the viewpoints of CPU load and network traffic load, it is feasible for the mobile nodes to take part in the overlay. Through energy consumption measurements, we draw the conclusion that in general the UMTS access mode consumes slightly more power than the WLAN access mode. Protocol packets with sizes of 200bytes or less are observed to be the most energy efficient in the UMTS access mode.

Energy consumption model for mobile devices in 3G and WLAN networks

In this paper, we propose an advanced model, called e-Aware, for estimating how application layer protocol properties affect the energy consumption of mobile devices, operating in 3G (WCDMA) and WLAN (802.11) networks. The main motivation for the model is to facilitate designing energy-efficient networking solutions, by reducing the need for time-consuming measurements with real-life networks and devices. The model makes a distinction between signaling and media transfers due to their different energy consumption characteristics, and takes into account the fundamentals of radio interface properties, such as different energy states and timers controlling them. The model is fine-tuned using device-specific coefficients that are defined according to real-world measurements with actual devices. We have implemented the model and simulated it in Matlab environment. The correct functionality is verified by comparing the results with real-life measurements in identical networking scenarios.

Battery life of mobile peers with UMTS and WLAN in a Kademlia-based P2P overlay

We evaluate the battery life of mobile devices that act as full-fledged peer nodes in a Kademlia DHT based P2P overlay network. The motivation is to find out how long a mobile peer is able to function in a UMTS or WLAN access network, and how the different parameter settings affect this battery life; this is interesting as mobile access to P2P networks is expected to become common in the near future. The majority of the peers in an overlay are simulated on a server array, while the power measurements are conducted on actual mobile devices. The variable overlay parameters are the number of peers, resource lookup activity, and the level of churn. The chosen values of parameters represent a relatively high amount of activity. In UMTS the measured battery life is approximately 3 hours and in WLAN it is 5 to 10 (most often around 8) hours. We also provide power measurements on sending and receiving UDP packets in UMTS and WLAN, for approximating the power consumption of network protocols without protocol-specific measurements.

Mobile Agents for Integration of Internet of Things and Wireless Sensor Networks

We demonstrate interoperable mobile agents to integrate Internet of Things and wireless sensor networks with resource-constrained low-power embedded networked devices. We introduce adaptable composition for the mobile agent, complying with the Representational State Transfer principles, which are then used for agent migration, controlling the agent and exposing the data, system resources, tasks and services, to the Web. We gather requirements for the system and heterogeneous networked devices and present an application programming interface to enable mobile agents in these systems. The agents are demonstrated in a real-world prototype with smartphones and embedded networked devices, where we utilize a proxy component to expose system resources to the Web for human-machine interactions. Spanning over disparate networks and protocols, the proxy translates messages including the agent composition, between HTTP and Constrained Application Protocol. Lastly, we suggest an evaluation method for the agent communication and migration costs, considering the different types of system resources and utilization.

An efficient selection algorithm for building a super-peer overlay

Super-peer overlay provides an efficient way to run applications by exploring the heterogeneity of nodes in a Peer-to-Peer overlay network. Identifying nodes with high capacity as super-peers plays an important role in improving the performance of P2P applications, such as live streaming. In this paper, we present a super-peer selection algorithm (SPS) to select super-peers for quickly building a super-peer overlay. In the SPS, each peer periodically builds its set of super-peer candidates through gossip communication with its neighbors, in order to select super-peers and client peers. Simulation results demonstrate that the SPS is efficient in selecting super-peers, and in quickly building a super-peer overlay. The proposed SPS also possesses good scalability and robustness to failure of super-peers.

Distributed resource directory architecture in Machine-to-Machine communications

Machine-to-Machine (M2M) communications emerge to achieve ubiquitous communications among all the networked devices. One challenging problem in M2M applications is to discover the resources provided by the devices efficiently. This challenge arises from two perspectives: (1) a large number of heterogeneous devices co-exist and most of them are constrained devices (e.g., limited processing capability), (2) different communication protocols are utilized to get access to different types of resources provided by the devices (e.g., humidity information provided by a sensor). This paper proposes distributed resource directory architecture for M2M applications, referred to as DRD4M. The DRD4M supports heterogeneous devices using HTTP and CoAP protocols for resource registration and lookup. This enables the interoperability among heterogeneous devices and resource access to constrained devices from disparate network including the Internet. The DRD4M introduces two components: a resource registration component for registering resources and a resource lookup component with caching functionality for handling resource lookup with filtering. A peer-to-peer (P2P) overlay is introduced in DRD4M to connect resource peers to avoid single point of failure. A real-world prototype is implemented and is verified with a demo application. Preliminary performance evaluation in terms of response time of resource lookup is provided.

Effects of different churn models on the performance of structured peer-to-peer networks

We present the effects of different churn models on the performance of structured peer-to-peer (P2P) networks in this paper. Specifically, Exponential distribution (ED), Pareto distribution (PD), and Weibull distribution (WD) are evaluated to provide a comparative analysis. Kademlia-based Peer-to-Peer Protocol (P2PP) is utilized as the underlying signaling protocol. Through simulations, we conclude that the simulated different churn models do not have a significant effect on the performance of the simulated structured P2P network. Quantitatively, ED and PD result in better performance compared to WD from the viewpoints of lookup success rate, mean network traffic load, and mean number of messages.

Interconnecting P2PSIP and IMS

Interpersonal communication using the information networks can be accomplished in many different ways. Users may communicate, for example, by using a specific communication application on an end-user terminal, typical mobile phone, or IP Multimedia Subsystem (IMS) client. Quite often there is no interconnection mechanisms between these different communication methods, and this is emphasized with regards to various communication applications. We propose an architecture for interconnecting Peer-to-peer Session Initiation Protocol (P2PSIP) and IMS networks. The actual gateway, that enables the interconnection, is seen as a peer in the P2PSIP side and as an application server (AS) in the IMS side. Furthermore, we present a prototype from the proposed interconnection architecture.