In recent literatures, WiFi signals have been widely used to "sense" people's locations and activities. Researchers have exploited the characteristics of wireless signals to "hear" people's talk and "see" keystrokes by human users. Inspired by the excellent work of relevant scholars, we turn to explore the field of human-computer interaction using finger-grained gestures under WiFi environment. In this paper, we present Wi-Finger - the first solution using ubiquitous wireless signals to achieve number text input in WiFi devices. We implement a prototype of WiFinger on a commercial Wi-Fi infrastructure. Our scheme is based on the key intuition that while performing a certain gesture, the fingers of a user move in a unique formation and direction and thus generate a unique pattern in the time series of Channel State Information (CSI) values. WiFinger is deigned to recognize a set of finger-grained gestures, which are further used to realize continuous text input in off-the-shelf WiFi devices. As the results show, WiFinger achieves up to 90.4% average classification accuracy for recognizing 9 digits finger-grained gestures from American Sign Language (ASL), and its average accuracy for single individual number text input in desktop reaches 82.67% within 90 digits.

In this work, we focus on designing high-throughput anycast mechanisms in a software Defined Network (SDN), as anycast routing serves as a fundamental building block for many services. Specifically, we investigate two main challenges for efficient implementation of a SDN-based anycast system: high throughput anycast routing (HTAR) and congestion-free anycast reconfiguration (CFAR). For the first challenge, we design an anycast routing (ARFU) algorithm, based on the fully polynomial time approximation scheme and the single-source unsplittable flow routing method. We prove that ARFU produces a route that can achieve a throughput at least 1/2(1+ξ) of the optimum, where ξ > 0 is an arbitrarily small constant. We then propose an anycast reconfiguration algorithm with transitive configurations, called ARTC, for congestion-free. This algorithm tries to find a routing reconfiguration procedure consisting of at most T ≥ 1 transitive configurations while meeting all the flow demands. When traffic demands can not be satisfied, ARTC maximizes the minimum throughput using one transitive configuration. Our simulations demonstrate high-efficiency of our algorithms.