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Recently, smart mobile devices and wireless communication technologies such as WiFi, third generation (3G), and long-term evolution (LTE) have been rapidly deployed. Many smart mobile device users can access the Internet wirelessly, which has increased mobile traffic. In 2014, more than half of the mobile traffic around the world was devoted to satisfying the increased demand for the video streaming. In this paper, we propose a scalable video streaming relay scheme. Because many collisions degrade the scalability of video streaming, we first separate networks to prevent excessive contention between devices. In addition, the member device controls the video download rate in order to adapt to video playback. If the data are sufficiently buffered, the member device stops the download. If not, it requests additional video data. We implemented apps to evaluate the proposed scheme and conducted experiments with smart mobile devices. The results showed that our scheme improves the scalability of video streaming in a wireless local area network (WLAN).

In this paper, we propose mobile ad hoc network configuration and its autonomous network construction method for efficiency and scalability of media streaming for mobile smart devices. To provide scalable network configuration for streaming traffic distribution, an IEEE 802.11 infrastructure network and ad hoc networks are hierarchically built. The proposed method autonomously configures a hierarchical streaming network by competition based on performance and states of devices and the wireless network, not depending on any specific nodes. Finally, we conduct performance measurement for the proposed configuration and analyze the experimental result.

We propose a synchronized playback method for the real-time synchronization of the playback position of streaming media to multiple clients from a streaming server. The playback-related information that is used in this synchronized playback method comprises the current time and the playback position, and the server transmits the playback position and the current time to the client. The client can determine the playback position of the server based on the playback position and the current time and can synchronize playback using this information. In this paper, we describe the configuration of the experimental environment for synchronized media playback and present the synchronization algorithms used in this method for both the server and the client. Then, we present a method for measuring the synchronization accuracy and the results of such measurements. The average synchronization accuracy is 26 msec. According to the Haas effect, the experimentally measured sync accuracy is sufficiently high that the corresponding sound error is not detectable by the human ear.

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