Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/37949
標題: System supports for protocol and application adaptation in vertical handoffs
作者: Chang, H.P.
張軒彬
Lin, Y.C.
Chen, S.H.
關鍵字: vertical handoff
heterogeneous networks
TCP
application adaptation
congestion control
wireless networks
performance
bandwidth
internet
dynamics
links
期刊/報告no:: Software-Practice & Experience, Volume 39, Issue 8, Page(s) 739-771.
摘要: In overlay networks, the network characteristics before and after a vertical handoff would be drastically different. Consequently, in this paper, we propose an end-to-end based scheme to support protocol and application adaptation in vertical handoffs. First, we proposed a Vertical-handoff Aware TCP, called VA-TCP. VA-TCP can identify the packet losses caused by vertical handoffs. If segments losses are due to vertical handoffs, VA-TCP only retransmits the missing segments but does not invoke the congestion control procedure. Moreover, VA-TCP dynamically estimates the bandwidth and round-trip time in a new network. Based on the estimated bandwidth and round-trip time, VA-TCP adjusts its parameters to respond to the new network environment. Second, during a vertical handoff, applications also need to be adapted accordingly. Therefore, we design a programming interface that allows applications to be notified upon and adapt to changing network environments. To support our interface, we utilize the signal mechanism to achieve kernel-to-user notification. Nevertheless, signals cannot carry information. Thus, we implement the shared memory mechanism between applications and the kernel to facilitate parameters exchange. Finally, we also provide a handoff-aware CPU scheduler so that tasks that are interested in the vertical-handoff event are given preference over other processes to attain a prompt response for new network conditions. We have implemented a prototype system on the Linux kernel 2.6. From the experimental results, our proposed protocol and application adaptation mechanisms are shown to effectively improve the performance of TCP and applications during vertical handoffs. Copyright (C) 2008 John Wiley & Sons, Ltd.
URI: http://hdl.handle.net/11455/37949
ISSN: 0038-0644
文章連結: http://dx.doi.org/10.1002/spe.910
Appears in Collections:資訊科學與工程學系所

文件中的檔案:

取得全文請前往華藝線上圖書館



Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.