The Internet of Things (IoT) shall be able to incorporate transparently and seamlessly a large number of different and heterogeneous end systems, while providing open access to selected subsets of data for the development of a plethora of digital services. Building a general architecture for the IoT is hence a very complex task, mainly because of the extremely large variety of devices, link layer technologies, and services that may be involved in such a system. In this paper, we focus specifically to an urban IoT system that, while still being quite a broad category, are characterized by their specific application domain. Urban IoTs, in fact, are designed to support the Smart City vision, which aims at exploiting the most advanced communication technologies to support added-value services for the administration of the city and for the citizens. This paper hence provides a comprehensive survey of the enabling technologies, protocols, and architecture for an urban IoT. Furthermore, the paper will present and discuss the technical solutions and best-practice guidelines adopted in the Padova Smart City project, a proof-of-concept deployment of an IoT island in the city of Padova, Italy, performed in collaboration with the city municipality.

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Internet of Things for Smart Cities

Efficient application scheduling is critical for achieving high performance in heterogeneous computing environments. The application scheduling problem has been shown to be NP-complete in general cases as well as in several restricted cases. Because of its key importance, this problem has been extensively studied and various algorithms have been proposed in the literature which are mainly for systems with homogeneous processors. Although there are a few algorithms in the literature for heterogeneous processors, they usually require significantly high scheduling costs and they may not deliver good quality schedules with lower costs. In this paper, we present two novel scheduling algorithms for a bounded number of heterogeneous processors with an objective to simultaneously meet high performance and fast scheduling time, which are called the Heterogeneous Earliest-Finish-Time (HEFT) algorithm and the Critical-Path-on-a-Processor (CPOP) algorithm. The HEFT algorithm selects the task with the highest upward rank value at each step and assigns the selected task to the processor, which minimizes its earliest finish time with an insertion-based approach. On the other hand, the CPOP algorithm uses the summation of upward and downward rank values for prioritizing tasks. Another difference is in the processor selection phase, which schedules the critical tasks onto the processor that minimizes the total execution time of the critical tasks. In order to provide a robust and unbiased comparison with the related work, a parametric graph generator was designed to generate weighted directed acyclic graphs with various characteristics. The comparison study, based on both randomly generated graphs and the graphs of some real applications, shows that our scheduling algorithms significantly surpass previous approaches in terms of both quality and cost of schedules, which are mainly presented with schedule length ratio, speedup, frequency of best results, and average scheduling time metrics.

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Performance-effective and low-complexity task scheduling for heterogeneous computing

In the Hamadryas baboon, males are substantially larger than females. A troop of baboons is subdivided into a number of ‘one-male groups’, consisting of one adult male and one or more females with their young. The male prevents any of ‘his’ females from moving too far from him. Kummer (1971) performed the following experiment. Two males, A and B, previously unknown to each other, were placed in a large enclosure. Male A was free to move about the enclosure, but male B was shut in a small cage, from which he could observe A but not interfere. A female, unknown to both males, was then placed in the enclosure. Within 20 minutes male A had persuaded the female to accept his ownership. Male B was then released into the open enclosure. Instead of challenging male A , B avoided any contact, accepting A’s ownership.

Evolution and the Theory of Games

https://www.engr.colostate.edu/~hj/journals/71.pdf

A Comparison of Eleven Static Heuristics for Mapping a Class of Independent Tasks onto Heterogeneous Distributed Computing Systems

Multiple applications request data from multiple storage units over a computer network. The data is divided into segments and each segment is distributed randomly on one of several storage units, independent of the storage units on which other segments of the media data are stored. At least one additional copy of each segment also is distributed randomly over the storage units, such that each segment is stored on at least two storage units. This random distribution of multiple copies of segments of data improves both scalability and reliability. When an application requests a selected segment of data, the request is processed by the storage unit with the shortest queue of requests. Random fluctuations in the load applied by multiple applications on multiple storage units are balanced nearly equally over all of the storage units. This combination of techniques results in a system which can transfer multiple, independent high-bandwidth streams of data in a scalable manner in both directions between multiple applications and multiple storage units.

Computer system and process for transferring multiple high bandwidth streams of data between multiple storage units and multiple applications in a scalable and reliable manner

This article addresses a new area of sensor networks — the anti-sensornet. Though the term anti-sensornet is scattered throughout literature, there is no systematic description of the anti-sensornet. In this article, we provide an introduction to anti-sensornet by analyzing the behaviors of intelligent intruders and the methods used to confront them including hiding sensor networks, enhancing detection capabilities and recovering from successful attacks.

Anti-sensornet: Intruders and countermeasure

We study mechanism designs for resource management in service overlay, where services are provided by strategic agents. Usually, resources in distributed systems are limited. However, the current mechanism design does not take the capacity of agents into consideration. Traditionally, the Vickrey- Clarke-Groves (VCG) mechanism has been the only method to design protocols so that each strategic agent will follow the protocols for its own interest to maximize its benefit. We show that the VCG mechanism is not truthful anymore when the capacity of agents is limited. Thus, we have designed, based on non-uniform prices, a new capacity-aware mechanism which subsidizes the service agents so that each agent maximizes its profit if it truthfully reports its cost. Mechanisms for two widely used pricing models are designed and evaluated.

Capacity-Aware Mechanisms for Service Overlay Design

Interference is a key factor that impacts the performance of wireless networks, especially when each node is equipped with multiple interfaces. Based on the classification criterion presented in this paper, we classify current interface assignment strategies into three types: static, dynamic and hybrid. We mainly address the problems of characterizing and evaluating interference effects of static strategy and two hybrid strategies in multi-interface wireless mesh networks. We prove that, if all links are bi-directional, both hybrid strategies described have identical interference characteristics. We derive formula for computing interference node set and channel interference possibility respectively. We also present an extensive evaluation via NS2 simulations. Compared to static strategy, the hybrid strategy yields more throughputs, higher traffic fairness and faster adaptation to traffic changes.

Characterizing and Evaluating Interference in Multi-Interface Wireless Mesh Networks

A wireless sensor network may consist of a large number of small, battery-powered, wireless sensor nodes and works in an unattended way. In order to manage the sensor network and collect data from the network efficiently, we need to know the state of the WSN. In this paper, we propose a model-aided approach to support the monitoring of the state of WSNs. In this approach, models are created on base station to support the monitoring of the network, and mobile agents are injected into the network to collect state information. Experimental results show the effectiveness of our approach.

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Monitoring wireless sensor networks using a model-aided approach

This paper presents GPR (Geographic Probabilistic Routing protocol), an opportunistic routing protocol worked between mesh routers in WMNs (Wireless Mesh Networks). In GPR, nodes detect the link condition by probe packets. In order to send a packet, the sender selects a candidate subset. The nodes who successfully received the packet send ACK according to their priority. If there are no ACKs from other candidates, instead of sending ACK immediately, the candidate broadcasts ACK and transmits the packet at transmission-probability. The extensive simulation results show that GPR is promising to achieve higher throughput and better scalability compared to the reference method.

Min-You Wu

Papers

Anti-sensornet: Intruders and countermeasure

Capacity-Aware Mechanisms for Service Overlay Design

Characterizing and Evaluating Interference in Multi-Interface Wireless Mesh Networks

Monitoring wireless sensor networks using a model-aided approach

Geographic probabilistic routing protocol for wireless mesh network