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

A video distribution architecture with edge stations and Wi-Fi delivery networks as connection to residential homes is described in this paper. An edge station is configurable and controllable by a central server. It is placed in the access point of Wi-Fi networks and has multiple usages. Due to its large storage space it can be used as a mirroring/caching proxy for continuous media. Replicating popular video contents in many small mirroring sites can significantly reduce the network bandwidth requirement. When this structure is used with a cable or hybrid fiber/coax (HFC) network, it turns to be a hybrid fiber/coaxAVi-Fi (HFCW) structure, particularly suitable for video-on-demand (VoD) applications. There are many advantages of this architecture. First, the central server load and network traffic can be reduced to a small percentage. Second, the response time of most video playing requests can be significantly reduced. Third, true VoD can possibly be provided with a one-way cable system. Finally, noise from STBs (set-top boxes) is absorbed by the edge station in a two-way cable system.

Video distribution with edge stations and Wi-Fi delivery networks

An effective approach for energy conservation in wireless sensor networks is putting redundant sensor nodes to sleep while the active nodes provide certain degree of coverage. This paper presents an Area-based Collaborative Sleeping protocol (ACOS) that can control the degree of coverage for diverse applications. The ACOS protocol, based on the net sensing area of a sensor, controls the mode of sensors to maximize the coverage, minimize the energy consumption, and to extend the lifetime of the sensor network. The net sensing area of a sensor is the area of the region exclusively covered by the sensor itself. We study the parameter tuning in ACOS to guide to configure the network for diverse applications. The simulation shows that our protocol has better coverage of the surveillance area while waking fewer sensors than other sleeping protocols. It extends the lifetime of sensor networks significantly

An area-based collaborative sleeping protocol for wireless sensor networks

One of the essential problems in parallel computing is: can STMD machines handle asynchronous problems? Thas is a dificult, unsolved problem because of the mismatch between asynchronous problems and SIMD archtiectures. We propose a soluiaon to let SIMD machines handle general asynchronous problems. Our approach is to implement a runtime support system which can run MIMD-like software on SIMD hardware. Substantial performance has been obtained on CM-2 and CM-5.

Solving Dynamic and Irregular Problems on SIMD Architectures with Runtime Support

The goal of the ShanghaiGrid is to provide information services to the people. It aims to construct a metropolitan-area information service infrastructure and establish an open standard for widespread upper-layer applications from both communities and the government. The Information Service Grid Toolkit and a typical application called the Traffic Information Grid are discussed in detail. Copyright © 2005 John Wiley & Sons, Ltd.

ShanghaiGrid: an Information Service Grid: Research Articles

In this paper, we study the channel allocation in multi-channel wireless ad hoc networks with directional antennas. In particular, we investigate the problem: given a set of wireless nodes equipped with directional antennas, how many channels are needed to ensure collision-free communications? We derive the upper bounds on the number of channels, which heavily depend on the node density and the interference ratio (i.e., the ratio of the interference range to the transmission range). We construct several scenarios to examine the tightness of the derived bounds. We also take the side-lobes and back-lobes as well as the signal path loss into our analysis. Our results can be used to estimate the number of channels required for a practical wireless network (e.g., wireless sensor network) with directional antennas.

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Min-You Wu

Papers

Video distribution with edge stations and Wi-Fi delivery networks

An area-based collaborative sleeping protocol for wireless sensor networks

Solving Dynamic and Irregular Problems on SIMD Architectures with Runtime Support

ShanghaiGrid: an Information Service Grid: Research Articles

Channel Allocation in Wireless Networks with Directional Antennas