With the rapid developments of IoT technologies, a large amount of real-time data is collected and shared, having important impacts on many applications, such as business advertisement and decision-making assistance. However, most users are unwilling to share their personal data directly to any third party for either academic research or commercial analysis because personal data contains private or sensitive information, such as economic status or living habits. Balancing the utility of big data and users' privacy is a vital issue in academia and industry. In this paper, a privacy-preserving r...