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This paper proposes a generic framework for monitoring continuous spatial queries over moving objects. The framework distinguishes itself from existing work by being the first to address the location update issue and to provide a common interface for monitoring mixed types of queries. Based on the notion of safe region, the client location update strategy(More)
—On-demand broadcast is an effective wireless data dissemination technique to enhance system scalability and deal with dynamic user access patterns. With the rapid growth of time-critical information services in emerging applications, there is an increasing need for the system to support timely data dissemination. This paper investigates online scheduling(More)
—Mobile location-dependent information services (LDISs) have become increasingly popular in recent years. However, data caching strategies for LDISs have thus far received little attention. In this paper, we study the issues of cache invalidation and cache replacement for location-dependent data under a geometric location model. We introduce a new(More)
Histograms are the workhorse of data mining and analysis. This paper considers the problem of publishing his-tograms under differential privacy, one of the strongest privacy models. Existing differentially private histogram publication schemes have shown that clustering (or grouping) is a promising idea to improve the accuracy of sanitized his-tograms.(More)
L ocation-dependent information services (LDISs) are an important class of context aware applications. They answer location-related queries, where a location is either explicit or implied. These services emerged from advances and convergence in high-speed wireless networks, personal portable devices, and location-identification techniques. With a variety of(More)
— This paper exploits the tradeoff between data quality and energy consumption to extend the lifetime of wireless sensor networks. We consider the applications that require some aggregate form of sensed data with precision guarantees. Our key idea is to differentiate the precisions of data collected from different sensor nodes to balance their energy(More)
—The rapid growth of new information services and business-oriented applications entails the consideration of quality of service (QoS) in content distribution. This paper investigates the QoS-aware replica placement problems for responsiveness QoS requirements. We consider two classes of service models: replica-aware services and replica-blind services. In(More)
We have been witnessing in the past few years the rapid growth of wireless data applications in the commercial market thanks to the advent of wireless devices, wireless high-speed networks, and supporting software technologies. We envisage that in the near future, a large number of mobile users carrying portable devices (e.g., palmtops, laptops, PDAs, WAP(More)
—Query processing that preserves both the data privacy of the owner and the query privacy of the client is a new research problem. It shows increasing importance as cloud computing drives more businesses to outsource their data and querying services. However, most existing studies, including those on data outsourcing, address the data privacy and query(More)
Caching frequently accessed data at the client is an attractive technique for improving access time. In a mobile computing environment , client location becomes a piece of changing information. As such, location-dependent data may become obsolete due to data updates or client movements. Most of the previous work investigated cache in-validation issues(More)