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The Internet of Medical Things (IoMT) is an extension and specialization of that original Internet of Things (IoT) concept, and applies to the interconnectedness of devices, software applications, and data which are specific to the medical industry. IoMT can add smart technologies to medical devices to monitor the progression of a disease away from the doctor’s office and learn things that could impact future care guidelines and patients. It can also provide a better way to care for our elderly by tracking vitals and heart performance, glucose and other body systems, and activity and sleeping levels. During the outbreak of pandemic (e.g., COVID-19), IoMT can even be used to detect main symptoms ubiquitously using intelligent sensors and trace the origin of the outbreak based on aggregated IoT data (e.g., geographic mobile data and purchase history). Although most of the contemporary IoMT systems can measure risks, make decisions, and take actions automatically, the lack of emotion-aware abilities will be an obstacle to more harmonious human–machine interaction and more efficient medical process. Besides, mental disorders, such as depression, schizophrenia, and anxiety, have become a more noticeable cause of suffering. The integration of emotion-aware abilities into IoMT can also contribute to monitor emotional dysregulation continuously in subjects with mental disorders or undergoing serious pandemic such as COVID-19, and give these patients personalized therapy recommendations. Research on affective computing has defined a framework to recognize, interpret, and process human affects, but more research is needed to investigate its application to biomedical applications, especially “in the wild” and over extended periods of time, and how to integrate emotion-aware abilities into IoMT organically is still an open question. This special issue aims to create a platform for researchers, developers, and practitioners from both academia and industry to disseminate the state-of-the-art results and to advance the Emotion-Aware ubiquitous computing in IoMT.

Motivated by complementing the ubiquitous wireless sensor networks (WSNs) and powerful cloud computing (CC), a lot of attention from both industry and academia has been drawn to Sensor-Cloud (SC). However, SC pricing is barely investigated. Towards pricing for SC, this paper 1) introduces five SC Pricing Models (SCPMs) first. Specifically, to charge a SC user, each SCPM considers one of the following factors respectively: i) the lease period of the SC user; ii) the required working time of SC; iii) the SC resources utilized by the SC user; iv) the volume of sensory data obtained by the SC user; v) the SC path that transmits sensory data from the WSN to the SC user. Further, this paper 2) performs analysis to discuss and exhibit the characteristics of the proposed SCPMs. With that, this paper 3) presents the case studies regarding the application of SCPMs. Eventually, this paper 4) conducts a review about the user behavior study. This paper aims to serve as a very favorable guidance for future research about pricing in SC.

Mobile edge computing (MEC) has risen as a promising paradigm to provide high quality of experience via relocating the cloud server in close proximity to smart mobile devices (SMDs). In MEC networks, the MEC server with computation capability and storage resource can jointly execute the latency-sensitive offloading tasks and cache the contents requested by SMDs. In order to minimize the total latency consumption of the computation tasks, we jointly consider computation offloading, content caching, and resource allocation as an integrated model, which is formulated as a mixed integer nonlinear programming (MINLP) problem. We design an asymmetric search tree and improve the branch and bound method to obtain a set of accurate decisions and resource allocation strategies. Furthermore, we introduce the auxiliary variables to reformulate the proposed model and apply the modified generalized benders decomposition method to solve the MINLP problem in polynomial computation complexity time. Simulation results demonstrate the superiority of the proposed schemes.

As the challenge of depression problems increases today, it is important to effective and timely detect for patients' treatments and depression prevention. Current methods of automated depression diagnosis depend almost entirely on audio, video, and Electroencephalogram (EEG) etc. In this paper, we propose a novel method to detect depression using gait data that is collected by Kinect camera. Its key components include a camera rectification method and a rigid-body representation of the human body. The camera rectification method achieves the purpose of improving data processing accuracy by changing the camera angle. The rigid-body representation can not only improve the robustness of detecting depression patients with noisy input, but also can reduce the classification time. We evaluate our method on the depression gait dataset in postgraduate students. The proposed method has an outstanding performance in classic machine learning algorithms, and the best accuracy can achieve 88.89%. Our solution provides a new method for automatic depression detection (ADD) that has exciting implications in clinical theory and practice, and has the advantages of high accuracy, inexpensive, low time cost, and no-contact.

With the expansion of the IoT, it is important to optimize available bandwidth to reliably support edge to device communications. Thus we propose a wireless network where each edge server communicates with its end devices using its wireless band as a primary channel, assisted by a secondary edge server that can relay communications via its own wireless band as a secondary channel. The network can optimize capacity by balancing load between primary and secondary wireless bands, and we analyze the geometry of achievable rate regions, depending on the state of bands modeled as Rayleigh fading channels. The allocation of a connection to the primary or secondary band is formulated as an optimization problem which is then solved, and illustrated with numerical examples.

Demand-based charges have been employed as a tool intended to reduce electricity users’ maximum demand but there is a lack of consensus regarding their efficacy. One reason for this may be the diversity in the flexibility potential of different types of users. This study explores the flexibility potential of different types of electricity consumers in the small to medium-sized commercial sector (35-63A) in response to a compulsory demand charge. The objective is to characterize varying levels of flexibility with respect to different types of commercial users with different load patterns. A multivariate clustering technique was used to group commercial users with comparable load patterns based on a year of hourly data before the tariff change was introduced. This method was used to: (1) match users from the intervention area and reference area with similar load patterns, without losing any user data, and (2) compare how users with different load patterns react differently to the tariff change. We found clear distinctions in the types of commercial users in each cluster and their response to the tariff, demonstrating the extent to which demand flexibility may be dependent on the nature of an organization’s activities and its respective load patterns. The highest demand flexibility was found in clusters which had a large share of users in the IT sector, commerce and public administration. The lowest demand flexibility was found in the real estate and education sectors. Future research should further investigate these variations and explore the possibilities of tailoring interventions to the specific types of users.

Air pollution is one of the major concerns in global urbanization. Data science can help to understand the dynamics of air pollution and build reliable statistical models to forecast air pollution levels. To achieve these goals, one needs to learn the statistical models which can capture the dynamics from the historical data and predict air pollution in the future. Furthermore, the large size and heterogeneity of today’s big urban data pose significant challenges on the scalability and flexibility of the statistical models. In this work, we present a scalable belief updating framework that is able to produce reliable predictions, using over millions of historical hourly air pollutant and meteorology records. We also present a non-parametric approach to learn the statistical model which reveals interesting periodical dynamics and correlations of the dataset. Based on the scalable belief update framework and the non-parametric model learning approach, we propose an iterative update algorithm to accelerate Gaussian process, which is notorious for its prohibitive computation with large input data. Finally, we demonstrate how to integrate information from heterogeneous data by regarding the beliefs produced by other models as the informative prior. Numerical examples and experimental results are presented to validate the proposed method.

Federated Learning (FL) is a promising paradigm to empower on-device intelligence in Industrial Internet of Things(IIoT) due to its capability of training machine learning models across multiple IIoT devices, while preserving the privacy of their local data. However, the distributed architecture of FL relies on aggregating the parameter list from the remote devices, which poses potential security risks caused by malicious devices. In this paper, we propose a flexible and robust aggregation rule, called Auto-weighted Geometric Median (AutoGM), and analyze the robustness against outliers in the inputs. To obtain the value of AutoGM, we design an algorithm based on alternating optimization strategy. Using AutoGM as aggregation rule, we propose two robust FL solutions, AutoGM_FL and AutoGM_PFL. AutoGM_FL learns a shared global model using the standard FL paradigm, and AutoGM_PFL learns a personalized model for each device. We conduct extensive experiments on the FEMNIST and Bosch IIoT datasets. The experimental results show that our solutions are robust against both model poisoning and data poisoning attacks. In particular, our solutions sustain high performance even when 30% of the nodes perform model or 50% of the nodes perform data poisoning attacks.

This paper presents an experimental study on real-time air pollution monitoring using wireless sensors on public transport vehicles. The study is part of the GreenIoT project in Sweden, which utilizes Internet-of-Things to measure air pollution level in the city center of Uppsala. Through deploying low-cost wireless sensors, it is possible to obtain more fine-grained and real-time air pollution levels at different locations. The sensors on public transport vehicles complement the readings from stationary sensors and the only ground level monitoring station in Uppsala. The paper describes the deployment of wireless sensors on Uppsala buses and the integration of the mobile sensor network with the GreenIoT testbed. Extensive experiments have been conducted to evaluate the communication quality and data quality of the system. Keywords: Smart city, Internet-of-Things, Mobile sensor network, Air pollution monitoring

As an emerging platform based on ITS, SIoV is promising for applications of traffic management and road safety in smart cities. However, the end-to-end delay is large in store-carry-and-forward-based vehicular networks, which has become the main obstacle for the implementation of large-scale SIoV. With the extensive applications of mobile devices, crowdsensing is promising to enable real-time content dissemination in a city-wide traffic management system. This article first provides an overview of several promising research areas for traffic management in SIoV. Given the significance of traffic management in urban areas, we investigate a crowdsensing-based framework to provide timely response for traffic management in heterogeneous SIoV. The participant vehicles based on D2D communications integrate trajectory and topology information to dynamically regulate their social behaviors according to network conditions. A real-world taxi trajectory analysis-based performance evaluation is provided to demonstrate the effectiveness of the designed framework. Furthermore, we discuss several future research challenges before concluding our work.

People’s health, mood, and activities are closely related to their environment and the seasons. Countries at extreme latitudes (e.g., Sweden, U.K., and Norway) experience huge variations in their light levels, impacting the population’s mental state, well-being and energy levels. Advanced sensing technologies on smartphones enable nonintrusive and longitudinal monitoring of user states. The collected data make it possible for healthcare professionals and individuals to diagnose and rectify problems caused by seasonality. In this paper, we present a personal mobile sensing system that exploits technologies on smartphones to efficiently and accurately detect the light exposure, mood, and activity levels of individuals. We conducted a 2-year experiment with many users to test the functionality and performance of our system. The results show that we can obtain accurate light exposure estimation by opportunistically measuring light data on smartphones, tracking both personal light exposure and the general seasonal trends. An optional questionnaire also provides insight into the correlation between a user’s mood and energy level. Our system is able to inform users how little light they are experiencing in the winter time. It can also correlate light exposure data with reduced mood and energy, and provide quantitative measurements for lifestyle changes.

The Internet of Things (IoT) enables environmental monitoring by collecting data from sensing devices, including cameras and microphones. The popularity of smartphones enables mobile users to communicate and collect data from their surrounding sensing devices. The mobile devices can obtain useful environmental data from nearby sensors through short-range communication such as Bluetooth. Nevertheless, the limited contact time and the wireless capacity constrain the amount of data to be collected. With the increasing amount of multimedia big data such as videos and pictures from cameras, it is crucial for mobile users to collect prioritized data that can maximize their data utility. In this paper, we propose a distributed algorithm to provide information-centric ubiquitous data collection of multimedia big data by mobile users in the IoT. The algorithm can handle transmissions of multimedia big data recorded by the surrounding cameras and sensors, and prioritize the transmissions of the most important and relevant data. The mobile users construct data collection trees adaptively according to their dynamic moving speeds and the value of information carried by the multimedia and sensor data. The distributed algorithm can support smooth data collection and coordination of multiple mobile users. We provide both numerical analysis and extensive simulations to evaluate the information value, energy efficiency and scalability of our solution. The results showed that our distributed algorithm can improve the value of information up to 50% and reduce energy consumption to half compared with existing approach. Our algorithm also scales perfectly well with increasing number of mobile users and dynamic moving speeds.

Due to the limitation of capacity in an enterprise, cooperation among these enterprises is necessary to handle a complex production task. Cloud manufacturing (CMF) provides a cooperation platform for efficient utilization of distributed manufacturing resources in regional enterprise cluster. However, effective scheduling of tasks or subtasks to these resources is a challenging problem. Based on the analysis on the procedure of task processing, this paper proposes a CMF scheduling model for efficiently exploiting distributed resources, so industrial robots in different enterprises can cooperatively handle a batch of tasks. Specifically, this paper considers the performance of four robot deployment methods, including random deployment, robot-balanced deployment, function-balanced deployment, and location-aware deployment. Furthermore, three subtask-scheduling strategies are derived for three optimization objectives, including load-balance of robots, minimizing overall cost, and minimizing overall processing time. Moreover, these strategies are implemented by genetic algorithm. Simulation results demonstrate that each strategy can achieve the relevant optimization objective. In addition, the results also show that the physical distance between two enterprises can influence the overall cost, and location-aware deployment leads to smaller transportation cost. Location-aware deployment and function-balanced deployment lead to smaller overall processing time for the low-workload state and high-workload state of the system, respectively.

The discovery of peoples' social connections is becoming a flourishing research topic, considering the rich social information inferable from human trajectories. Existing social tie detection methods often require mobile users to upload their accurate locations, causing serious privacy concerns. On the other hand, cloaking methods allow users to upload their obscured locations instead and can efficiently protect their location privacy. However, no existing social tie detection method can generate social relationships among users when only obscured trajectories are provided. To tackle the aforementioned problem, this paper proposes a novel semantic-tree-based algorithm. Specifically, we model the obscured regions from the cloaking algorithm as a semantic region tree and assign weight values for regions based on their popularity, further indicating the similarity between users based on their temporal and spatial relations. We evaluate our proposed approach using a real trajectory data set and show that our algorithm can identify social ties successfully with 20% higher accuracy than the existing approaches.

In recent years, Information-centric Networking (ICN) has received much attention from both academic and industry participants. ICN offers data-centric inter-networking that is radically different from today's host-based IP networks. Security and privacy features on today's Internet were originally not present and have been incrementally retrofitted over the last 35 years. As such, these issues have become increasingly important as ICN technology gradually matures towards real-world deployment. Thus, while ICN-based architectures (e.g., NDN, CCNx, etc.) are still evolving, it is both timely and important to explore ICN security and privacy issues as well as devise and assess possible mitigation techniques. This report documents the highlights and outcomes of the Dagstuhl Seminar 16251 on ``Information-centric Networking and Security.'' The goal of which was to bring together researchers to discuss and address security and privacy issues particular to ICN-based architectures. Upon finishing the three-day workshop, the outlook of ICN is still unclear. Many unsolved and ill-addressed problems remain, such as namespace and identity management, object security and forward secrecy, and privacy. Regardless of the fate of ICN, one thing is certain: much more research and practical experience with these systems is needed to make progress towards solving these arduous problems.

There has been significant interest in the use of HTTP adaptive streaming for live or on-demand video over the Internet in recent years. To mitigate the streaming transmission delay and reduce the networking overhead, an effective and critical approach is to utilize cache services between the origin servers and the heterogeneous clients. As the underlying protocol for web transactions, HTTP has great potentials to explore the resources within state-of-the-art CDNs for caching; yet distinct challenges arise in the HTTP adaptive streaming context. After examining a long-term and large-scale adaptive streaming dataset as well as statistical analysis, we demonstrate that the switching requests among the different qualities frequently emerge and constitute a significant portion in a per-day view. Consequently, they have substantially affected the performance of cache servers and Quality-of-Experience (QoE) of viewers. In this paper, we propose a novel cache model that captures the dependency among the segments in the cache server for adaptive HTTP streaming. Our work does not assume any specific selection algorithm on the client’s side and hence can be easily incorporated into existing streaming cache systems. Its centralized nature is also well accommodated by the latest DASH specification. Moreover, we extend our work to the multi-server caching context and present a similarity-aware allocation mechanism to enhance the caching efficiency. The performance evaluation shows our dependency- and similarity-aware strategy can significantly improve the cache hit-ratio and QoE of HTTP streaming as compared to previous approaches.

Batteries of modern mobile devices remain severely limited in capacity, which makes energy consumption a key concern for mobile applications, particularly for the computation-intensive video applications. Mobile devices can save energy by offloading computation tasks to the cloud, yet the energy gain must exceed the additional communication cost for cloud migration to be beneficial. The situation is further complicated by real-time video applications that have stringent delay and bandwidth constraints. In this paper, we closely examine the performance and energy efficiency of representative mobile cloud applications under dynamic wireless network channels and state-of-the-art mobile platforms. We identify the unique challenges of and opportunities for offloading real-time video applications and develop a generic model for energy-efficient computation offloading accordingly in this context. We propose a scheduling algorithm that makes adaptive offloading decisions in fine granularity in dynamic wireless network conditions and verify its effectiveness through trace-driven simulations. We further present case studies with advanced mobile platforms and practical applications to demonstrate the superiority of our solution and the substantial gain of our approach over baseline approaches.

The papers in this special section focus on data-driven Internet of Things (IoT) for smart cities. Developing smart cities to better support the growing urban population is a global and complex challenge and involves interdisciplinary fields. Instead of the traditional Internet of Contents in human-to-human and human-to-machine communications, the Internet of Things with communications among massive numbers of sensors will dominate the network traffic. Every day, these smart things generate a massive amount of data in the magnitude of ZettaBytes. Due to inherent characteristics of geo-distribution in big data generated by networked sensors deployed for IoT applications, the “smartness” of infrastructure in future cities requires intelligent data sensing and mining for monitoring and actuation to ensure infrastructure reliability and public safety.

Building an intelligent and resilient city is a global mission for both research communities and the general public. Recent advancement on Internet-of-Things (IoT) and machine learning enable new solutions and applications, such as smart energy systems and autonomous vehicles. In the past, most of the IoT systems report sensor data to the cloud and perform machine learning. However, this centralized approach causes high communication overheads and delay. In this paper, we present a distributed machine learning framework for IoT in smart cities. It enables machine learning algorithms to be run on heterogeneous nodes with different capabilities, including end devices, edge devices, and the cloud. We first describe a distributed machine learning-assisted framework for network management in IoT for smart cities. We then provide a case study of urban monitoring using vehicular sensor network. A secure and distributed information fusion scheme based on statistical machine learning is proposed. Finally, we discuss potential extensions on scalable computation and other distributed machine learning methods for large scale networks.

The Internet of Things (IoT) has become a promising technology for addressing societal challenges by connecting smart devices and leveraging Big Data analytics to create smart cities worldwide. As the IoT scales up, it's important to provide interoperability among different devices. Yet current simple standard protocols lack sufficient openness and interoperability. IoT for smart cities needs to guarantee the accessibility of open data and cloud services to allow industries and citizens to develop new services and applications. Here, the authors provide a case study of the GreenIoT platform in Uppsala, Sweden, to demonstrate the idea of interoperability and open data for smart cities.

This article analyzes security vulnerabilities in bandwidth allocation and request mechanisms that are specified in the IEEE 802.16 Standard, and introduces a bandwidth request adversary model called UL-BRA based on these vulnerabilities. The goal of UL-BRA is to abuse the bandwidth request/grant operation of a WiMAX network, resulting in a significant decrease of the overall uplink transmission performance of the network. To overcome the challenge caused by the vulnerabilities of the standard, we propose a security patch incorporating a real-time anomaly detection and restoration (RADR) mechanism, which combines an MCDR scheme with an ATD scheme in order to eliminate the impacts of UL-BRA in real-time. We verify the effectiveness of RADR under UL-BRA threats via simulations, and demonstrate the effectiveness of the proposed patch in mitigating the threats of UL-BRA.

The Internet of Things (IoT) is connecting people and smart devices on a scale that was once unimaginable. One major challenge for the IoT is to handle vast amount of sensing data generated from the smart devices that are resource-limited and subject to missing data due to link or node failures. By exploring cloud computing with the IoT, we present a cloud-based solution that takes into account the link quality and spatio-temporal correlation of data to minimize energy consumption by selecting sensors for sampling and relaying data. We propose a multiphase adaptive sensing algorithm with belief propagation (BP) protocol (ASBP), which can provide high data quality and reduce energy consumption by turning on only a small number of nodes in the network. We formulate the sensor selection problem and solve it using both constraint programming (CP) and greedy search. We then use our message passing algorithm (BP) for performing inference to reconstruct the missing sensing data. ASBP is evaluated based on the data collected from real sensors. The results show that while maintaining a satisfactory level of data quality and prediction accuracy, ASBP can provide load balancing among sensors successfully and preserves 80% more energy compared with the case where all sensor nodes are actively involved.

To meet the demand of increasing mobile data traffic and provide better user experience, heterogeneous cellular networks (HCNs) have become a promising solution to improve both the system capacity and coverage. However, due to dense self-deployment of small cells in a limited area, serious interference from nearby base stations may occur, which results in severe performance degradation. To mitigate downlink interference and utilize spectrum resources more efficiently, we present a novel graph-based resource allocation and interference management approach in this paper. First, we divide small cells into cell clusters, considering their neighborhood relationships in the scenario. Then, we develop another graph clustering scheme to group user equipment (UE) in each cell cluster into UE clusters with minimum intracluster interference. Finally, we utilize a proportional fairness scheduling scheme to assign subchannels to each UE cluster and allocate power using water-filling method. To show the efficacy and effectiveness of our proposed approach, we propose a dual-based approach to search for optimal solutions as the baseline for comparisons. Furthermore, we compare the graph-based approach with the state of the art and a distributed approach without interference coordination. The simulation results show that our graph-based approach reaches more than 90% of the optimal performance and achieves a significant improvement in spectral efficiency compared with the state of the art and the distributed approach both under cochannel and orthogonal deployments. Moreover, the proposed graph-based approach has low computation complexity, making it feasible for real-time implementation.

The papers in this special section focus on the Internet of Things for use in smart cities and urban informatics. CITIES around the world are currently under quick transition toward a low-carbon environment, high quality of living, and resource-efficient economy. Smart systems are crucial components for building sustainable cities and aggregating comprehensive urban informatics. Internet-of-Things (IoT) is an emerging technology evolved from the convergence of wireless technologies, embedded systems, and the Internet. Extensive research on IoT is taking place on sensing and automatic control, network infrastructure and communication, and big data analytics. This facilitates a multidisciplinary approach for developing integrated solutions and creating novel applications to build a sustainable society. Combinations of IoT with autonomous systems, machine intelligence, sensor and actuator networks provide smart functions in wide application domains, including environmental monitoring, smart transportation, industrial production, and security surveillance. This special section on Internet-of-Things for smart cities and urban informatics is focused on the development, adoption, and application of IoT technology to improve the efficiency of cities and enhance urban services in society. It covers topics including smart transportation, smart buildings, data transmission and analytics, system designs, and experiments of IoT for smart cities.

Mobile social networks (MSNs) have become increasingly popular in supporting many novel applications since emerging in the recent years. Their applications and services are of great interest to service providers, application developers, and users. This paper distinguishes MSNs from conventional social networks and provides a comprehensive survey of MSNs with regard to platforms, solutions, and designs of the overall system architecture. We review the popular MSN platforms and experimental solutions for existing MSN applications and services and present the dominant mobile operating systems on which MSNs are implemented. We then analyze and propose the overall architectural designs of conventional and future MSN systems. In particular, we present the architectural designs from two perspectives: from the client side to the server side, and from the wireless data transmission level to the terminal utilization level. We further introduce and compare the unique features, services, and key technologies of two generations of architectural designs of MSN systems. Then, we classify the existing MSN applications and propose one special form of MSN, i.e., vehicular social network, and demonstrate its unique features and challenges compared with common MSNs. Finally, we summarize the major challenges for on-going MSN research and outline possible future research directions.

Smart world is envisioned as an era in which objects (e.g., watches, mobile phones, computers, cars, buses, and trains) can automatically and intelligently serve people in a collaborative manner. Paving the way for smart world, Internet of Things (IoT) connects everything in the smart world. Motivated by achieving a sustainable smart world, this paper discusses various technologies and issues regarding green IoT, which further reduces the energy consumption of IoT. Particularly, an overview regarding IoT and green IoT is performed first. Then, the hot green information and communications technologies (ICTs) (e.g., green radio-frequency identification, green wireless sensor network, green cloud computing, green machine to machine, and green data center) enabling green IoT are studied, and general green ICT principles are summarized. Furthermore, the latest developments and future vision about sensor cloud, which is a novel paradigm in green IoT, are reviewed and introduced, respectively. Finally, future research directions and open problems about green IoT are presented. Our work targets to be an enlightening and latest guidance for research with respect to green IoT and smart world.

In recent years, there has been a growing interest in the ability of embedded devices, sensors, and actuators to communicate, and create a ubiquitous cyber-physical world. The growth of the notion of the Internet of Things (IoT) and the rapid development of technologies such as short range mobile communication and improved energy-efficiency is expected to create a pervasive connection of “things.” This will inevitably result in the generation of enormous amount of data, which have to be stored, processed, and accessed. Cloud computing has long been recognized as a paradigm for big data storage and analytics. The combination of cloud computing and IoT can enable ubiquitous sensing services and powerful processing of sensing data streams beyond the capability of individual things, thus stimulating innovations in both fields. For example, cloud platforms allow the sensing data to be stored and used intelligently for smart monitoring and actuation with the smart devices. Novel data fusion algorithms, machine learning methods, and artificial intelligence techniques can be implemented and run centralized or distributed on the cloud to achieve automated decision making. These will boost the development of new applications, such as smart cities, grids, and transportation systems. New challenges, however, arise when IoT meets cloud—there is an urgent need for novel network architectures that seamlessly integrate them, and protocols that facilitate big data streaming from IoT to the cloud. QoS and QoE, as well as data security, privacy, and reliability, are critical concerns during the integration.

Attribute-Based Encryption (ABE) is considered to be one of the most promising ways to be enforce access control in Information-Centric Networking (ICN). As the Internet of Things (IoT) is being considered as one of the primary use cases for ICN it raises the question of the compatibility between IoT and ABE. An important part of the IoT is the resource constrained devices, for them there is a challenge to perform the computationally expensive operations required for ABE. In this paper we consider ABE in sensor networks and discuss the strengths and weaknesses of a system solution where the ABE operations are performed on the sensors. To properly discuss these concerns we have implemented two ABE schemes, a Single-authority ABE (SA-CP-ABE) scheme and a Multi-authority ABE (MA-CP-ABE) scheme. Results regarding the execution time, RAM usage, data overhead and battery consumption of these implementations on a sensor are presented. We conclude that it is possible, already today, to perform ABE on sensors for smaller policies. The main limitation in deploying ABE in sensors is the RAM size of the sensors.

Wireless sensor networks (WSN) based on unmanned aerial vehicles (UAV) are ideal platforms for monitoring dynamics over larger service area. On the other hand, aerial sensor networks (ASNs) are often required to be connected with a command center for sending data and receiving control messages in real time. In this paper, we study the problem of path planning for ASNs with connectivity constraints. The primary goal of path planning is driving UAVs to locations where the most informative measurements can be collected. Meanwhile, the worst link's capacity is assured to be greater than a pre-defined requirement. We proposed a solution for the path planning problem and it consists of two modules: network coordinator (NC) and motion controller (MC). The NC manages the topology of relay-assisted wireless communication networks. For the design of MC, we compare two motion strategies: maximum entropy and maximum mutual information. The simulation results show that our proposed solution achieves accurate signal reconstruction while maintaining the connectivity. We conclude that it's important to enable UAV-to-UAV communications for future ASN-based applications.

This paper proposes a novel power management solution for resource-constrained devices in the context of Internet of Things (IoT). We focus on smartphones in the IoT, as they are getting increasingly popular and equipped with strong sensing capabilities. Smartphones have complex and asynchronous power consumption incurred by heterogeneous components including their on-board sensors. Their interaction with the cloud allows them to offload computation tasks and access remote data storage. In this work, we aim at monitoring the power consumption behaviours of the smartphones, profiling both individual applications and the system as a whole, to make better decisions in power management. We design a cloud orchestration architecture as an epic predictor of behaviours of smart devices by extracting their application characteristics and resource utilization. We design and implement this architecture to perform energy profiling and data analysis on massive data logs. This cloud orchestration architecture coordinates a number of cloud-based services and supports dynamic workflows between service components, which can reduce energy consumption in the energy profiling process itself. Experimental results showed that small portion of applications dominate the energy consumption of smartphones. Heuristic profiling can effectively reduce energy consumption in data logging and communications without scarifying the accuracy of power monitoring.

Cloud gaming considered as the future of computer games enables users to play high-end games on resource-const rained heterogeneous devices. Games are rendered on remote clouds and delivered to users via the Internet in the form of video streaming, which can dramatically reduce the consumption of client-side resources. However, such service needs high bandwidth connections to make the game streaming smooth, which is already a major issue to hamper the prevalence of cloud gaming. In this paper, we propose a gamer experience-centric bitrate control algorithm called GECKO, to reduce the consumption of bandwidth resources for cloud gaming while only slightly impairing user quality-of-experience (QoE). Through measurement studies, we find that user QoE is mainly determined by the ROI (Region of Interest) size and QP offset. Hence, in order to save bandwidth consumption without severely impairing user QoE, we can lower the quality of the region outside of ROI. Our proposed GECKO algorithm is designed to adaptively tune the size of ROI and the quality of the outside region. We implement the GECKO algorithm on a real cloud gaming platform. The experiment results show that over 15.8% bandwidth can be saved compared with state-of-the-art approaches. Refereed/Peer-reviewed

With the prevalence of localization techniques in smartphones, location-based applications on mobiles have become increasingly popular. However, only minorities of applications can be triggered automatically by the predefined locations of interest without any human interaction. One reason is that the inevitable operation of location detection by GPS is power-intensive. While existing work has focused on energy efficiency in continuous location tracking, energy-efficient location detection for matching predefined location of interest remains to be further explored. This paper proposes a unified framework that supports energy-efficient location detection for automatic location-triggered applications. Our framework triggers desired events only when the user is approaching the predefined locations of interest. Besides the efforts we make to reduce the number of GPS updates by cooperating with other types of on-device sensors, the framework also aims to coordinate multiple location-triggered applications to further reduce energy consumption on location updates. We implemented our framework as a middleware in the Android operating system and conducted extensive real experiments. The experimental results demonstrate that our framework can reduce the number of GPS requests and low the energy consumption of the smartphones significantly.

This article proposes a multidimensional context-aware social network architecture, which aims to provide a mobile ecosystem to enable context awareness in the development and utilization of mobile crowdsensing applications. This mobile ecosystem is constructed to provide context awareness capabilities for different roles (i.e., users or developers) in the system and facilitate interactions between them. This system can ease the development of context-aware mobile applications, and enable context-aware mobile crowdsensing considering environmental, personal, and social information. We present a flow of context-aware solutions designed on this system, and highlight the orchestrations and advantages of different context-aware schemes in the system for different types of users (requesters and participants) in mobile crowdsensing. We demonstrate the feasibility of the proposed mobile ecosystem by presenting a novel contextaware mobile crowdsensing application called Smart City, and evaluate the system performance based on this application.

Quality of information (QoI) in sensor networks measures information attributes such as precision, timeliness, completeness, and relevance of data ultimately delivered to users. It is a challenge t ...

Recent advances in cloud technology have turned the idea of cloud gaming into a reality. Cloud gaming, in its simplest form, renders an interactive gaming application remotely in the cloud and streams the scenes as a video sequence back to the player over the Internet. This is an advantage for less powerful computational devices that are otherwise incapable of running high-quality games. Such industrial pioneers as Onlive and Gaikai have seen success in the market with large user bases. In this article, we conduct a systematic analysis of state-of-the-art cloud gaming platforms, and highlight the uniqueness of their framework design. We also measure their real world performance with different types of games, for both interaction latency and streaming quality, revealing critical challenges toward the widespread deployment of cloud gaming.

Digital media covers larger parts of our daily lives nowadays. Mobile services enable a better connected society where citizens can easily access public services, discover events, and obtain important information in the city. We observe the popularity of mobile car sharing applications, such as Uber and Didi Dache. Mobile social applications provide new ways of developing and optimizing public transportation. In this paper, we present a mobile platform for timetable-free traveling. It can capture the traffic demand of citizens in real-time, and support efficient planning and scheduling for vehicles on-demand. At the moment, the platform is targeted for public bus services, but it has great potential to be extended for self-driving vehicles in the future.

There has been significant interest in the use of HTTP adaptive streaming for live or on-demand video over the Internet in recent years. To mitigate the streaming transmission delay and reduce the networking overhead, an effective and critical approach is to utilize cache servers between the origin servers and the heterogeneous clients. As the underlying protocol for web transactions, HTTP has great potentials to explore the resources within state-of-the-art CDNs for caching; yet distinct challenges arise in the HTTP adaptive streaming context. After examining a long-term and large-scale adaptive streaming dataset as well as statistical analysis, we demonstrate that the switching requests among the different qualities frequently emerge and constitute a significant portion in a per-day view. Consequently, they have substantially affected the performance of cache servers and Quality-of-Experience (QoE) of viewers. In this paper, we propose a novel cache model that captures the dependency among the segments in the cache server for adaptive HTTP streaming. Our work does not assume any specific selection algorithm on the client's side and hence can be easily incorporated into existing streaming cache system. Its centralized nature is also well accommodated by the latest DASH specification. The performance evaluation shows our dependency-aware strategy can significantly improved the cache hit-ratio and QoE of HTTP streaming as compared to previous methods.

Location information is a key element of participatory sensing. Many mobile and sensing applications require location information to provide better recommendations, object search and trip planning. However, continuous GPS positioning consumes much energy, which may drain the battery of mobile devices quickly. Although WiFi and cell tower positioning are alternatives, they provide lower accuracy compared to GPS. This paper solves the above problem by proposing a novel localization scheme through the collaboration of multiple mobile devices to reduce energy consumption and provide accurate positioning. Under our scheme, the mobile devices are divided into three groups, namely the broadcaster group, the location information receiver group and the normal participant group. Only the broadcaster group and the normal participant group use their GPS. The location information receiver group, on the other hand, makes use of the locations broadcast by the broadcaster group to estimate their locations. We formulate the broadcaster set selection problem and propose two novel algorithms to minimize the energy consumption in collaborative localization. Simulations with real traces show that our proposed solution can save up to 68% of the energy of all of the participants and provide more accurate locations than WiFi and cellular network positioning. Published version

The rapid development of the Internet of Things (IoT) has provided innovative solutions to reduce traffic accidents caused by fatigue driving. When drivers are in bad mood or tired, their vigilance level decreases, which may prolong the reaction time to emergency situation and lead to serious accidents. With the help of mobile sensing and mood-fatigue detection, drivers’ mood-fatigue status can be detected while driving, and then appropriate measures can be taken to eliminate the fatigue or negative mood to increase the level of vigilance. This paper presents the basic concepts and current solutions of mood-fatigue detection and some common solutions like mobile sensing and cloud computing techniques. After that, we introduce some emerging platforms which designed to promote safe driving. Finally, we summarize the major challenges in mood-fatigue detection of drivers, and outline the future research directions.

Wireless sensor networks have been widely deployed to perform sensing constantly at specific locations, but their energy consumption and deployment cost are of great concern. With the popularity and advanced technologies of mobile phones, participatory urban sensing is a rising and promising field which utilizes mobile phones as mobile sensors to collect data, though it is hard to guarantee the sensing quality and availability under the dynamic behaviors and mobility of human beings. Based on the above observations, we suggest that wireless sensors and mobile phones can complement each other to perform collaborative sensing efficiently with satisfactory quality and availability. In this paper, a novel collaborative sensing paradigm which integrates and supports wireless sensors and mobile phones with different communication standards is designed. We propose a seamless integrated framework which minimizes the number of wireless sensors deployed, while providing high sensing quality and availability to satisfy the application requirements. The dynamic sensing behaviors and mobility of mobile phone participants make it extremely challenging to estimate their sensing quality and availability, so as to deploy the wireless sensors at the optimal locations to guarantee the sensing performance at a minimum cost. We introduce two mathematical models, a sensing quality evaluation model and a mobility prediction model, to predict the sensing quality and mobility of the mobile phone participants. We further propose a cost-effective sensor deployment algorithm to guarantee the required coverage probability and sensing quality for the system. Extensive simulations with real mobile traces demonstrate that the proposed paradigm can integrate wireless sensors and mobile phones seamlessly for satisfactory sensing quality and availability with minimized number of sensors.

Sinks usually broadcast their addresses for data collection in sensor networks. However, this common operation opens up vulnerability for adversary to attack the sinks and obstruct their normal functions. In this paper, we suggest sink anonymity as a novel approach for data collection, which protects the privacy of the sinks and avoids them from becoming the target of attacks. We provide sink anonymity by omitting the address of the sink in routing, so that the identity and location of the sink are kept private. Our proposed Randomized Routing with Hidden Address RRHA scheme prevents the attackers from obtaining the receiver address by capturing the destination field of the packets or predicting the location of the sinks by observing the flow of network traffic. We examined the successful delivery rate, packet travel delay, and protection strength of our proposed scheme by both analysis and simulations. Copyright © 2010 John Wiley & Sons, Ltd.

Wireless sensor-actuator networks (WSANs) greatly enhance the existing wireless sensor network architecture by introducing powerful and possibly even mobile actuators. The actuators work with the sensor nodes, but can perform much richer application-specific actions. To act responsively and accurately, an efficient and reliable reporting scheme is crucial for the sensors to inform the actuators about the environmental events. Unfortunately, the low-power multi-hop communications in a WSAN are inherently unreliable; frequent sensor failures and excessive delays due to congestion or in-network data aggregation further aggravate the problem. In this paper, we propose a general reliability-centric framework for event reporting in WSANs. We argue that the reliability in such a real-time system depends not only on the accuracy, but also the importance and freshness of the reported data. Our design follows this argument and seamlessly integrates three key modules that process the event data, namely, an efficient and fault-tolerant event data aggregation algorithm, a delay-aware data transmission protocol, and an adaptive actuator allocation algorithm for unevenly distributed events. Our transmission protocol adopts smart priority scheduling that differentiates event data of non-uniform importance. We further extend the protocol to handle node and link failures using an adaptive replication algorithm. We evaluate our framework through extensive simulations; the results demonstrate that it achieves desirable reliability with minimized delay.

Wireless sensor-actuator networks (WSANs) have recently been suggested as an extension to conventional sensor networks. The powerful and mobile actuators can patrol along different routes and communicate with the static sensor nodes. Obviously, it is crucial to optimize the routes for the actuators to collect the sensor data in a timely fashion. Given the nonuniform and time-varying distribution of sensors and events in large networks, the route design has to be dynamic and scalable as well as balance the loads of the actuators. In this paper, we propose probabilistic route design (PROUD), which is an effective and adaptive algorithm for weight-differentiated route calculation. PROUD constructs an a priori route that covers the sensor locations, following which, the actuators probabilistically and cyclically visit the sensor locations according to their weights. We show that this probabilistic approach adapts well to network dynamics without frequent recalculation of the whole route. It works for both small-scale sensor-actuator networks and large-scale sensor-actuator networks with partitioning. We further develop a distributed implementation of PROUD and extend it to accommodate actuators with variable speeds. Finally, we devise a multiroute improvement and a task-exchange algorithm that enable load balancing. Our performance evaluation shows that PROUD effectively reduces the overall data-collection time and evenly distributes the energy consumption across the actuators, as compared with other state-of-the-art solutions.

Sensor networks (SNs) consist of spatially distributed sensors which monitor an environment, and which are connected to some sinks or backbone system to which the sensor data is being forwarded. In many cases, the sensor nodes themselves can serve as intermediate nodes for data coming from other nodes, on the way to the sinks. Much of the traffic carried by SNs will originate from routine measurements or observations by sensors that monitor a particular situation, such as the temperature and humidity in a room or the infrared observation of the perimeter of a house, so that the volume of routine traffic resulting from such observations may be quite high. When important and unusual events occur, such as a sudden fire breaking out or the arrival of an intruder, it will be necessary to convey this new information very urgently through the network to a designated set of sink nodes where this information can be processed and dealt with. This paper addresses the important challenge by avoiding the routine background traffic from creating delays or bottlenecks that impede the rapid delivery of high priority traffic resulting from the unusual events. Specifically we propose a novel technique, the ‘Randomized Re-Routing Algorithm (RRR)’, which detects the presence of novel events in a distributed manner, and dynamically disperses the background traffic towards secondary paths in the network, while creating a ‘fast track path’ which provides better delay and better quality of service (QoS) for the high priority traffic which is carrying the new information. When the surge of new information has subsided, this is again detected by the nodes and the nodes progressively revert to best QoS or shortest-path routing for all the ongoing traffic. The proposed technique is evaluated using a mathematical model as well as simulations, and is also compared with a standard node by a node priority scheduling technique.

Location based services are getting increasingly popular in participatory sensing systems. They make use of location information on the mobile devices to support applications that improve personal health, object search, and entertainment. However, GPS positioning consumes a lot of energy, which can drain a mobile device's battery. Although WiFi localization and cell tower localization have been suggested as alternatives, they have lower localization accuracy and limited coverage. In this paper, we suggest a novel solution for multiple mobile devices to perform collaborative localization to reduce energy consumption and provide accurate localization. We divide the mobile devices into two groups, the aggregator group and the collector group. The aggregator group turns on their GPS periodically, while the collector group uses the locations of the aggregators to estimate their own locations. We formulate the aggregator set selection problem and propose two novel algorithms to minimize the energy consumption in collaborative localization. Simulations with real traces showed that our proposed solution can save up to 88% of the energy of the entire network.

Road safety is a huge concern due to the large number of fatalities and injuries caused by road accidents. Research has shown that fatigue can adversely affect driving performance and increase risk of road accidents. It has been shown that driving performance is enhanced by stress-relieving music which thereby promotes safer driving. Context-aware music delivery systems promote safer driving through intelligent music recommendations based on contextual knowledge. Two key aspects of situation-aware music delivery are effectiveness and efficiency of music recommendation. Efficiency is a critical aspect in real-time context based music recommendation as the music delivery system should quickly sense any change in the situation and deliver suitable music before the sensed context-data becomes obsolete. We focus on the efficiency of situation-aware music delivery systems in this paper. Music mood-mapping is a process which helps in understanding the mood of a song and is hence used in situation-aware music recommendation systems. This process requires a large processing time due to the complex calculations and large sizes of music files involved. Hence, optimizing this process is the key to improving the efficiency of context-aware music delivery systems. Here, we propose a novel cloud and crowd-sensing based approach to considerably optimize the efficiency of situation-aware music delivery systems.

This paper proposes a novel power management solution for resource-constrained devices in the context of Internet of Things (IoT). We focus on smartphones in the IoT, as they are getting increasingly popular and equipped with strong sensing capabilities. Smartphones have complex and asynchronous power consumption incurred by heterogeneous components including their on-board sensors. Their interaction with the cloud allows them to offload computation tasks and access remote data storage. In this work, we aim at monitoring the power consumption behaviours of the smartphones, profiling both individual applications and the system as a whole, to make better decisions in power management. We design a cloud orchestration architecture as an epic predictor of behaviours of smart devices by extracting their application characteristics and resource utilization. We design and implement this architecture to perform energy profiling and data analysis on massive data logs. This cloud orchestration architecture coordinates a number of cloud-based services and supports dynamic workflows between service components, which can reduce energy consumption in the energy profiling process itself. Experimental results showed that small portion of applications dominate the energy consumption of smartphones. Heuristic profiling can effectively reduce energy consumption in data logging and communications without scarifying the accuracy of power monitoring.

Incorporating ubiquitous wireless sensor networks (WSNs) and powerful cloud computing (CC), Sensor-Cloud (SC) is attracting growing attention from both academia and industry. However, pricing for SC is barely explored. In this paper, filling this gap, five SC pricing models (i.e., SCPM1, SCPM2, SCPM3, SCPM4 and SCPM5) are proposed first. Particularly, they charge a SC user, based on 1) the lease period of the user, 2) the required working time of SC, 3) the SC resources utilized by the user, 4) the volume of sensory data obtained by the user, 5) the SC path that transmits sensory data from the WSN to the user, respectively. Further, analysis is also presented to study and demonstrate the performance of the proposed SCPMs. We believe that the pricing designs and analysis performed in this work could be a very valuable guidance for future researches regarding pricing in SC.