Power-aware anomaly detection in smartphones: An analysis of on-platform versus externalized operation

Many security problems in smartphones and other smart devices are approached from an anomaly detection perspective in which the main goal reduces to identifying anomalous activity patterns. Since machine learning algorithms are generally used to build such detectors, one major challenge is adapting these techniques to battery-powered devices. Many recent works simply assume that on-platform detection is prohibitive and suggest using offloaded (i.e., cloud-based) engines. Such a strategy seeks to save battery life by exchanging computation and communication costs, but it still remains unclear whether this is optimal or not in all circumstances. In this paper, we evaluate different strategies for offloading certain functional tasks in machine learning based detection systems. Our experimental results confirm the intuition that outsourced computation is clearly the best option in terms of power consumption, outweighing on-platform strategies in, essentially, all practical scenarios. Our findings also point out noticeable differences among different machine learning algorithms, and we provide separate consumption models for functional blocks (data preprocessing, training, test, and communications) that can be used to obtain power consumption estimates and compare detectors.     

INFFC: An iterative class noise filter based on the fusion of classifiers with noise sensitivity control

In classification, noise may deteriorate the system performance and increase the complexity of the models built. In order to mitigate its consequences, several approaches have been proposed in the literature. Among them, noise filtering, which removes noisy examples from the training data, is one of the most used techniques. This paper proposes a new noise filtering method that combines several filtering strategies in order to increase the accuracy of the classification algorithms used after the filtering process. The filtering is based on the fusion of the predictions of several classifiers used to detect the presence of noise. We translate the idea behind multiple classifier systems, where the information gathered from different models is combined, to noise filtering. In this way, we consider the combination of classifiers instead of using only one to detect noise. Additionally, the proposed method follows an iterative noise filtering scheme that allows us to avoid the usage of detected noisy examples in each new iteration of the filtering process. Finally, we introduce a noisy score to control the filtering sensitivity, in such a way that the amount of noisy examples removed in each iteration can be adapted to the necessities of the practitioner. The first two strategies (use of multiple classifiers and iterative filtering) are used to improve the filtering accuracy, whereas the last one (the noisy score) controls the level of conservation of the filter removing potentially noisy examples. The validity of the proposed method is studied in an exhaustive experimental study. We compare the new filtering method against several state-of-the-art methods to deal with datasets with class noise and study their efficacy in three classifiers with different sensitivity to noise.