Browsing by Author "Yu, Tai-Xing"

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Load Balancing Apparatus And Method In Wireless Network Hotspots
(2008-04-10)
Tsao, Shiao-Li
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Hsu, Chih-Chien
;
Yu, Tai-Xing
Disclosed is a load balancing apparatus and method in wireless network hotspots, which comprises a resource allocation module and a load balancer. The resources reallocation module establishes the resources module and the relationship between access points (APs) and STAs in the wireless network hotspots, and seeks possible load balance shift paths (LBSPs). From these possible LBSPs, an LBSP is selected. Based on the selected LBSP, the load balancer reallocates network resources and dynamically arranges the load among the APs in the wireless network hotspots. This invention can be applicable to a centralized or a decentralized wireless communication system.
Rank-Based Network Coding for Content Distribution in Vehicular Networks
(2012-08)
Yu, Tai-Xing
;
Yi, Chih-Wei
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Tsao, Shiao-Li
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資訊工程學系
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Department of Computer Science
We propose a rank-based network coding scheme for distributing content in vehicular ad-hoc networks, in which vehicles adaptively broadcast packets based on the content reception status of their neighbors. In contrast to the previous work, CodeOn, vehicles in the proposed method only exchange content reception information in the service channel. The packet injection probability in the proposed method is proportional to the estimated innovation that a vehicle can provide to its neighbors. We also give an analytical model to analyze the system throughput when vehicles apply rank-based network coding to broadcast data. Simulation results demonstrate that the proposed method improves the throughput by more than 32% while maintaining lower end-to-end delay and protocol overhead than the previous work.
Reducing Voice over WLAN Call Setup Delay under Limited Access Point Buffer
(2006)
Tsao, Shiao-Li
;
Yu, Tai-Xing
;
資訊工程學系
;
Department of Computer Science
Voice over WLAN (VoWLAN) service is regarded as one of the killer applications for public and private WLANs' but it suffers from a number of technical challenges, especially the power consumption problem. In order to conserve the energy of a VoWLAN device during idle, the power saving mode (PSM) defined in the IEEE 802.11 is widely employed. Experimental results indicate that 300ms to 1000ms listen intervals of PSM for a VoWLAN device could achieve better energy efficiencies. Unfortunately, low-end WLAN access points (APs) typically have limited memory spaces, and can buffer incoming packets for a small time window, say 100ms. For a VoWLAN device requesting long listen intervals, packets queued on the APs might be dropped or overwritten when the buffer overflows. This phenomenon introduces considerable call setup delays for session initiation protocol (SIP) that implements the exponential retransmission mechanism of lost messages. This study investigates the problem and proposes three approaches to reduce call setup delays for VoWLAN applications. Simulation results demonstrate that the proposed mechanisms reduce call setup delays significantly for low-power VoWLAN devices.