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Popular location-based services through smart-phones and other portable devices have brought the tracking of user mobility to the attention in wireless community and have increased its importance continuously. Although the incremental development of GPS technology made the measurement of speed and location of the device more accurate, speed itself cannot fully express the mobility and therefore limits its use in Human and Computer Interaction (HCI). HCI makes user-oriented services possible by interacting computing devices with an user through certain types of I/Os such as keyboards, touch pads and various sensors. It is true that the location and speed of user provides fundamental mobility information for service generators in the world of HCI, but now it is time to give a little deeper aspect of giving user mobility beyond the term speed. In this paper, we scrutinize sensing device motility resulted from human motion and its impact on user mobility estimation, called mobility state, in order to provide conceptual and comprehensive means of mobility including speed. Then we propose Device & User mobility Tracking Algorithm (DUTA) that accurately assess the mobility state without incurring unnecessary power consumption.

Smartphones and portable devices are widely used these days. Data transmission networks such as 3G and Wi-Fi are used for most smartphones, and LTE is quickly increasing its market share in order to support enormous network users who cause data congestion on every part of network topology. Especially, wireless part of network suffers from starvation and congestion due to many users who wish high quality Internet service such as HD video streaming. In this paper, we propose an efficient mechanism of auto-connecting qualified Wi-Fi network for the next generation smartphones in order to provide acceptable Internet service for device users. One of authentication-free access points and others that are provided by contracted Internet service provider can be automatically connected with the mechanism. Also, quality of experience (QoE) of the connected AP is guaranteed by estimating Signal to Interference and Noise Ratio (SINR) which is derived by the number of stations sharing the same channel. We implemented the proposed mechanism in both Android phone and also OPNET simulation, and also we conducted a performance evaluation study. The simulation results indicate that the proposed mechanism retains the best set of candidate APs to be connected and improves the MAC layer throughput.

In this paper, we propose a hybrid platform for mobile broadcasting and telecommunication. This platform, the ‘Web-based smart DMB platform’, targets smart mobile devices with terrestrial Digital Multimedia Broadcasting (T-DMB) functionality. Due to the success of smart phones, many video services via the Internet have been developed and telecommunication companies are trying to enter the broadcasting market. The development of this platform originated with the idea that, in this smart device era, mobile TV services must evolve to be more attractive and smarter than ever before. Broadcasting systems have to adopt more advanced features like those of smart devices, including openness, convergence, participation, etc. As the first step to the ideal platform, the Korean Broadcasting System (KBS) has developed core technologies and systems which combine T-DMB video over the air and multimedia services via the Internet on Web pages. To demonstrate the potential of the proposed platform, we present a prototype system and some experimental services.

Mobile devices with a singular radio cannot avoid the connection-off period when they move around in different transmission ranges of neighboring devices. In order to minimize the connection-off duration on singular radio mobile devices, we propose the Proactive Searching-Period Determination (PSPD) algorithm, which determines an optimal period for information exchange among neighboring nodes in the presence of mobile nodes. In order to verify the effectiveness of the PSPD, we carried out a simulation study with ns-2. The simulation results shows that the proposed algorithm correctly determines an optimal period and minimizes the connection-off duration for mobile nodes.