With the significant improvement in IoT technology and smart devices, data collection and distributed computation have led a foundation for Mobile crowd-sensing (MCS). MCS utilizes the capabilities of embedded sensors in smart devices for gathering data. MCS benefits both data provider (participant/user), and data requester, i.e. data providers via incentives/rewards, data requesters by delivering required data. Apart from the benefits gained through acquiring data, confronting challenges such as participant privacy, data trustworthiness, malicious attacks (from illegitimate users) need to be addressed to build robust and reliable data solicitation. In addition to that, it is necessary to consider user motivation and user preference, comfort during its engagement in crowd-sensing. User preferences/constraints can be due to privacy concerns in terms of location, the sensitivity of data or energy usage and many more. With this in mind, the main contributions of the thesis can be listed as follows. 1) We design user selective trustworthy data acquisition frameworks. We introduce a variety of user selection criteria to form participant communities based on participants reliability and income. To evaluate the trustworthiness of our selective reputation-based data acquisition, we consider malicious users in the environment and calculate the total rewards given to malicious users. Simulations results show that community formation based on the acquired income of participants ended up with a substantial loss to the cloud platform as well as participants. Contrary to that, reputation-based community formation has shown nearly equal platform utility (profit), negligible loss of user utility compared to benchmark Non-selective data acquisition with 7% malicious probability. 2) Moreover, we attempt to enable users to modify (allow/deny access to) their builtin sensor set according to their comfort levels. We formulate three comfort levels high (only allow access to sensors that would not directly reveal personal identity such as accelerometer, light sensor, etc.), moderate (obstruct access to sensitive data, e.g. camera), zero comfort (allow access to all users). We introduce Static modification, where users pre-arrange their sensor set before the start of data collection. Our feasibility study shows that pre-arrangement of the sensor set favours user comfort, user utility at the cost of loss in platform utility and performs better than selective reputation-based recruitment for the considered settings. 3) We apply Adaptive sensor modification on top of pre-arrangement of sensor set through which participants are authorized to re-arrange their sensor availability based on reliability scores. Simulation results show that the Adaptive comfort-aware approach performed better than static in terms of platform utility and achieved comparatively better user comfort with reasonable loss in user utility.

abstract: The presence of a rich set of embedded sensors on mobile devices has been fuelling various sensing applications regarding the activities of individuals and their surrounding environment, and these ubiquitous sensing-capable mobile devices are pushing the new paradigm of Mobile Crowd Sensing (MCS) from concept to reality. MCS aims to outsource sensing data collection to mobile users and it could revolutionize the traditional ways of sensing data collection and processing. In the meantime, cloud computing provides cloud-backed infrastructures for mobile devices to provision their capabilities with network access. With enormous computational and storage resources along with sufficient bandwidth, it functions as the hub to handle the sensing service requests from sensing service consumers and coordinate sensing task assignment among eligible mobile users to reach a desired quality of sensing service. This paper studies the problem of sensing task assignment to mobile device owners with specific spatio-temporal traits to minimize the cost and maximize the utility in MCS while adhering to QoS constraints. Greedy approaches and hybrid solutions combined with bee algorithms are explored to address the problem. Moreover, the privacy concerns arise with the widespread deployment of MCS from both the data contributors and the sensing service consumers. The uploaded sensing data, especially those tagged with spatio-temporal information, will disclose the personal information of the data contributors. In addition, the sensing service requests can reveal the personal interests of service consumers. To address the privacy issues, this paper constructs a new framework named Privacy-Preserving Mobile Crowd Sensing (PP-MCS) to leverage the sensing capabilities of ubiquitous mobile devices and cloud infrastructures. PP-MCS has a distributed architecture without relying on trusted third parties for privacy-preservation. In PP-MCS, the sensing service consumers can retrieve data without revealing the real data contributors. Besides, the individual sensing records can be compared against the aggregation result while keeping the values of sensing records unknown, and the k-nearest neighbors could be approximately identified without privacy leaks. As such, the privacy of the data contributors and the sensing service consumers can be protected to the greatest extent possible. / Dissertation/Thesis / Doctoral Dissertation Computer Science 2016

Mobile Crowd Sensing (MCS) or Participatory Sensing (PS) are two emerging systems as smart mobile devices become ubiquitous. One of the advantages of such a sensing system is that almost anyone with a mobile device can become a moving "sensor". However, despite the convenience, the openness of such systems is a double-edged sword: participants can misbehave and pose a threat. Usually, current MCS or PS systems are relatively weak and lack effective data sources selection mechanisms. As a result, fake or forged data can be collected, representing wrongly the sensed conditions on the surroundings, i.e. noise, moisture, etc. Therefore, a Hardened Registration Process (HRP) is proposed to provide a pre-examination on participants that are chosen to collect sensing data. There is one previous work on such a topic. It targets device examination (root, emulator, bot-net detection, etc.) for Android devices, preventing attackers from managing to register not actual but emulated devices and thus manage to effectively manipulate the collected data. The focus of this project is on enhancing the previous work and extending it with complementary mechanisms. We proposed a two-step HRP process, comprising a client detection for identifying malicious devices and server-side detection for revealing Sybil devices. We improve the previous HRP by implementing detection mechanisms in C (native) code and such an enhanced device examination process is the first step: client detection. In addition, to detect adversaries that can bypass the client detection method, we proposed an additional server-side detection to eliminate emulators and Sybil devices, adopting peer-to-peer interaction with Bluetooth Low Energy to corroborate the physical presence of the registered devices. With this enhancement, we achieve higher detection performance. Adversaries cannot easily bypass the client-side detection with rooted or emulated devices. Moreover, even if some adversaries can bypass the client-side detection, the server-side detection can prevent adversaries from registering Sybil devices more than the number of devices they own. / Mobile Crowd Sensing (MCS) eller Participatory Sensing (PS) är två framväxande system när smarta mobila enheter blir allestädes närvarande. En av fördelarna med ett sådant avkänningssystem är att nästan alla med en mobil enhet kan bli en rörlig sensor". Men trots bekvämligheten är öppenheten i sådana system ett tveeggat svärd: deltagare kan missköta sig och utgöra ett hot. Vanligtvis är nuvarande MCS- eller PS-system relativt svaga och saknar effektiva valmekanismer för datakällor. Som ett resultat kan falska eller förfalskade data samlas in, som felaktigt representerar de avkända förhållandena i omgivningen, d.v.s. buller, fukt, etc. Därför föreslås en förstärkt registreringsprocess för att ge en förundersökning av deltagare som väljs för att samla in avkänningsdata. Det finns ett tidigare arbete om ett sådant ämne. Det är inriktat på enhetsundersökning (root, emulator, bot-net-detektion, etc.) för Android-enheter, vilket förhindrar angripare från att lyckas registrera inte faktiska utan emulerade enheter och på så sätt lyckas effektivt manipulera den insamlade informationen. Fokus för detta projekt ligger på att förbättra det tidigare arbetet och utöka det med kompletterande mekanismer. Vi föreslog en tvåstegs HRP-process, som omfattar en klientdetektering för att identifiera skadliga enheter och detektering på serversidan för att avslöja Sybil-enheter. Vi förbättrar den tidigare HRP genom att implementera detekteringsmekanismer i C (native) kod och en sådan förbättrad enhetsundersökningsprocess är det första steget: klientdetektering. Dessutom, för att upptäcka motståndare som kan kringgå klientdetekteringsmetoden, föreslog vi en extra detektering på serversidan för att eliminera emulatorer och Sybil-enheter, genom att använda peer-to-peer-interaktion med Bluetooth Low Energy för att bekräfta den fysiska närvaron av de registrerade enheterna. Med denna förbättring uppnår vi högre detektionsprestanda. Motståndare kan inte lätt kringgå upptäckten på klientsidan med rotade eller emulerade enheter. Dessutom, även om vissa motståndare kan kringgå upptäckten på klientsidan, kan detekteringen på serversidan förhindra att motståndarna registrerar Sybil-enheter mer än antalet enheter de äger.

De nos jours, il y a une demande croissante pour fournir de l'information temps réel à partir de l'environnement, e.g. état infectieux de maladies, force du signal, conditions de circulation, qualité de l'air. La prolifération des dispositifs de capteurs et la mobilité des personnes font de la Mobile Collaborative Sensing (MCS) un moyen efficace de détecter et collecter l'information à un faible coût. Dans MCS, au lieu de déployer des capteurs statiques dans une zone, les personnes disposant d'appareils mobiles jouent le rôle de capteurs mobiles. En général, une application MCS exige que l'appareil de chacun ait la capacité d'effectuer la détection et retourne les résultats à un serveur central, mais également de collaborer avec d'autres dispositifs. Pour que les résultats puissent représenter l'information physique d'une région cible et convenir, quel type de données peut être utilisé et quel type d'information doit être inclus dans les données collectées? Les données spatio-temporelles peuvent être utilisées par des applications pour bien représenter la région cible. Dans des applications différentes, l'information de localisation et de temps sont 2 types d'information communes, et en les utilisant la région cible d'une application est sous surveillance complète du temps et de l'espace. Différentes applications nécessitent de l'information différente pour atteindre des objectifs différents. E.g. dans cette thèse: i- MCS-Locating application: l'information de résistance du signal doit être incluse dans les données détectées par des dispositifs mobiles à partir d'émetteurs de signaux ; ii- MCS-Prédiction application : la relation entre les cas d'infection et les cas infectés doit être incluse dans les données par les dispositifs mobiles provenant des zones de flambée de la maladie ; iii- MCS-Routing application : l'information routière en temps réel provenant de différentes routes de circulation doit être incluse dans les données détectées par des dispositifs embarqués. Avec la détection de l'information physique d'une région cible, et la mise en interaction des dispositifs, 3 thèmes d'optimisation basés sur la détection sont étudiés et 4 travaux de recherche menés: -Mobile Collaboratif Détection Cadre : un cadre mobile de détection collaborative est conçu pour faciliter la coopérativité de la collecte, du partage et de l'analyse des données. Les données sont collectées à partir de sources et de points temporels différents. Pour le déploiement du cadre dans les applications, les défis clés pertinents et les problèmes ouverts sont discutés. -MCS-Locating : l'algorithme LiCS (Locating in Collaborative Sensing based Data Space) est proposé pour atteindre la localisation de la cible. LiCS utilise la puissance du signal reçu dans tous les périphériques sans fil comme empreintes digitales de localisation pour les différents emplacements. De sorte LiCS peut être directement pris en charge par l'infrastructure sans fil standard. Il utilise des données de trace d'appareils mobiles d'individus, et un modèle d'estimation d'emplacement. Il forme le modèle d'estimation de localisation en utilisant les données de trace pour atteindre la localisation de la cible collaborative. Cette collaboration entre périphériques est au niveau des données et est supportée par un modèle. -MCS-Prédiction: un modèle de reconnaissance est conçu pour acquérir dynamiquement la connaissance de structure de la RCN pertinente pendant la propagation de la maladie. Sur ce modèle, un algorithme de prédiction est proposé pour prédire le paramètre R. i.e. le nombre de reproduction qui est utilisé pour quantifier la dynamique de la maladie pendant sa propagation. -MCS-Routing : un algorithme de navigation écologique ‘eRouting’ est conçu en combinant l'information de trafic temps réel et un modèle d'énergie/émission basé sur des facteurs représentatifs. Sur la base de l'infrastructure standard d'un système de trafic intelligent, l'information sur le trafic est collectée / Nowadays, there is an increasing demand to provide real-time information from the environment, e.g., the infection status of infectious diseases, signal strength, traffic conditions, and air quality, to citizens in urban areas for various purposes. The proliferation of sensor-equipped devices and the mobility of people are making Mobile Collaborative Sensing (MCS) an effective way to sense and collect information at a low deployment cost. In MCS, instead of just deploying static sensors in an interested area, people with mobile devices play the role of mobile sensors to sense the information of their surroundings, and the communication network (3G, WiFi, etc.) is used to transfer data for MCS applications. Typically, a MCS application not only requires each participant's mobile device to possess the capability of performing sensing and returning sensed results to a central server, but also requires to collaborate with other mobile and static devices. In order to make sensed results well represent the physical information of a target region, and well be suitable to a certain application, what kind of data can be used for different applications, and what kind of information needs to be included into the collected sensing data? Spatio-temporal data can be used by different applications to well represent the target region. In different applications, location and time information is two kinds of common information, and by using such information, the target region of an application is under comprehensive monitoring from the view of time and space. Different applications require different information to achieve different sensing purposes. E.g. in this thesis: i- MCS-Locating application: signal strength information needs to be included into the sensed data by mobile devices from signal transmitters; ii- MCS-Prediction application: the relationship between infecting and infected cases needs to be included into the sensed data by mobile devices from disease outbreak areas; iii- MCS-Routing application: real-time traffic and road information from different traffic roads, e.g., traffic velocity and road gradient, needs to be included into the sensed data by road-embedded and vehicle-mounted devices. With sensing the physical information of a target region, and making mobile and static devices collaborate with each other in mind, in this thesis three sensing based optimization applications are studied, and following four research works are conducted: - a MCS Framework is designed to facilitate the cooperativity of data collection, sharing, and analysis among different devices. Data is collected from different sources and time points. For deploying the framework into applications, relevant key challenges and open issues are discussed. - MCS-Locating: an algorithm LiCS (Locating in Collaborative Sensing based Data Space) is proposed to achieve target locating. It uses Received Signal Strength that exists in any wireless devices as location fingerprints to differentiate different locations, so it can be directly supported by off-the-shelf wireless infrastructure. LiCS uses trace data from individuals' mobile devices, and a location estimation model. It trains the location estimation model by using the trace data to achieve collaborative target locating. Such collaboration between different devices is data-level, and model-supported. - MCS-Prediction: a recognition model is designed to dynamically acquire the structure knowledge of the relevant RCN during disease spread. On the basis of this model, a prediction algorithm is proposed to predict the parameter R. R is the reproductive number which is used to quantify the disease dynamics during disease spread. - MCS-Routing: an eco-friendly navigation algorithm, eRouting, is designed by combining real-time traffic information and a representative factor based energy/emission model. Based on the off-the-shelf infrastructure of an intelligent traffic system, the traffic information is collected