基於MIH換手架構改良式串流畫面更新率控制機制之研究

The Study of a Novel Seamless Streaming Playback Control Scheme for MIH-based Handover

吳振宇(Chen-Yu Wu)

指導教授 ： 李維聰

淡江大學/工學院/電機工程學系碩士在職專班/碩士(2013年)

https://doi.org/10.6846/TKU.2013.00460

摘要

隨著無線網路技術的蓬勃發展，各種異質的無線網路技術(例如：IEEE 802.1x系列、3GPP等)已逐漸形成一種無所不在的網路環境。而當行動裝置在異質網路環境中移動時，會出現執行換手的情況，會造成行動裝置的網路暫時中斷，進而造成使用者所觀看的多媒體檔案，會有播放延遲與停頓等現象。IEEE為訂定異質性無線網路間的換手標準機制，提出IEEE 802.21標準，其中定義一個中介層函式增加異質網路換手技術間的互通性，而該中介層被稱作Media Independent Handover (MIH) function，而隨著MIH的接受度增加，如何整合上層應用服務與MIH機制，已成為一個重要課題。先前研究已整合多媒體串流服務與MIH機制，實現無縫串流服務，透過在用戶裝置端整合MIH層與緩衝區管理機制，針對影像存量，提出漸進式調整畫面更新率機制，畫面更新率會隨著時間以等差級數下降改變，影像的播放將逐漸減慢，直到換手結束或畫面數不足而影像中斷。然而，直線式的變更畫面更新率，容易產生使用者體驗(Quality of experience, QoE)差異過大、緩衝區存量較少及可支撐換手時間較短的問題。

為改善使用者體驗(QoE)與增加較多緩衝區存量與支撐換手時間，本研究針對影像存量，提出二個改良方法，一個是曲線式的緩降，另一是曲線式的驟降，畫面更新率將以曲線式的方式下降，籍此可調整影像播放的時間長短，讓使用者有更佳的影像體驗。並將二者與漸進式調整作效能比較，前者可提升在換手時使用者觀看網路影片的畫面更新率，但播放時間較漸進式的短，後者則可以讓使用者在換手快結束時的畫面更新率下降的幅度趨緩，可讓使用者在觀看網路影片時有更佳的體驗。

關鍵字

換手 ； 緩衝區管理 ； 畫面更新率控制 ； 無線網路

並列摘要

Nowadays more and more people access and exchange information of any kind freely at anytime, from anywhere, and from any appliance through the use of heterogeneous network technologies (such as IEEE 802.1 series protocols and 3GPP). Mobile video streaming services and its’ performance are interrupted by the handover events when switching among the heterogeneous networks. The IEEE organization has provided the standard IEEE 802.21(MIH) to facilitate handover process among different radio technologies. A previous work, so-called Service Specific layer (SSL) scheme, was used to integrate a buffer management scheme with MIH for seamless streaming by extending the playing time of video stream but is short of quality of experience (QoE) consideration.

A smooth handover mechanism was proposed in this thesis to provide the better QoE in any type of heterogeneous networks environments than previous linear frame rate adjustment methods. Furthermore when the handover is finished, the mobile devices resume the transmission and restore the video steaming to the mobile device buffer. By this mechanism it brings the video stream restore to the buffer more expeditiously.

並列關鍵字

Handover ； Buffer Management ； Frame Rate Control ； Wireless Networks

參考文獻

[1]林弘偉."基於IEEE 802.21之動態調整群播影像的畫面更新率以達成無縫式換手之研究". 淡江大學電機工程學系碩士班學位論文,(2010年)

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