Search

The improvement in hardware capabilities of mobile devices has led to the active use of processor-heavy contents, such as multimedia files, on resource-limited platforms. In addition to simply enjoying such contents on mobile devices, recently commercialized protocols allow the real-time sharing of multimedia (or a mobile device's screen contents) with neighboring devices via wireless connection. However, unlike PC-scale computing platforms, use-case expansions on mobile devices face an additional technical challenge. Specifically, while the improved computation power is capable of handling processor-hungry applications, battery limitations hold back their full utilization. This paper acknowledges the fact that screen sharing on mobile devices can be attractive, but empirically show that minimizing the energy consumption is crutial, and introduces enhancements to the widely used H.264 encoder on mobile devices. Specifically, our enhancements target to minimize the transmission size of multimedia contents by analyzing the screen's dynamics. For contents with high dynamics, our scheme tries to maintain the video quality, while aggressively skipping frames for regions with minimal motion intensity. Our empirical evaluations show that the proposed light-weight enhancements reduce the size of a typical multimedia file by $\sim \hbox{42}$ %, while maintaining a high user-perceived quality (e.g., Structural SIMilarity measure) of 0.925. Wirelessly sharing this video results in $\sim \hbox{31}$ % lower frame transmission rate and up to $\sim \hbox{21}$ % power savings in less dynamic regions.

Vast volumes of time series are becoming more common in part to recent research advancements in big data analytics and sensor/monitoring networks. However, tranmission of time series for visualization services can cause serious bandwidth wastage and extensive network delays if there is no efficient data management. Existing work such as M4 aim to solve this problem by providing high data reduction rates through data aggregation and guaranteeing the reliability of visualization results at the same time. However, current work on M4 does not consider verification in a more practical environment; for example experimentation on web-based servers that are openly accessible by users. In this paper, we propose inter-pixel gradient-based M4 (IGM4) for enhancing the existing M4 scheme, and conduct a study to reduce the amount of data and delay without distorting the results of visualized graph. We build user-friendly web-based system to dealing with the data processing technique, and perform test on the empirical environment. Finally, we present the results of performance evaluation through comparison among the original data, M4, and IGM4 reflecting the various kinds of time series and resolutions.

This letter proposes a novel buffer management scheme for improving the packet delivery of Universal Serial Bus (USB) services in wireless networks. In the future, USB may be used with various wireless services, most notably Wi-Fi, thus realizing Wi-Fi USB (WSB). However, data transmission of Wi-Fi and USB is asynchronous due to differences in their Medium Access Control (MAC), resulting in buffer overflow. To alleviate this problem, we propose an overflow prevention scheme where rates of USB transmission are varied depending on status of Wi-Fi. The proposed scheme is evaluated via the NS-3 simulator, showing that the packet delivery ratio of USB data can reach near 100% even in wireless transmission.

A challenge faced by smart grid systems is providing highly reliable transmissions to better serve different types of electrical applications and improve the energy efficiency of the system. Although wireless networking technologies can provide highspeed and cost-effective solutions, their performance may be impaired by various factors that affect the reliability of smart grid networks. Here, we first suggest the use of IEEE 802.11s-based wireless LAN mesh networks as high-speed wireless backbone networks for smart grid infrastructure to provide high scalability and flexibility while ensuring low installation and management costs. Thereafter, we analyze some vital problems of the IEEE 802.11s default routing protocol (named hybrid wireless mesh protocol; HWMP) from the perspective of transfer reliability, and propose appropriate solutions with a new routing method called HWMP-reliability enhancement to improve the routing reliability of 802.11s-based smart grid mesh networking. A simulation study using ns-3 was conducted to demonstrate the superiorityof the proposed schemes.