在WCDMA系統中多媒體傳輸的排程式傳送機制; An Adaptive Scheduled Transmission Strategy for Multimedia Services in WCDMA Systems

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Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/8858

Title:	在WCDMA系統中多媒體傳輸的排程式傳送機制;An Adaptive Scheduled Transmission Strategy for Multimedia Services in WCDMA Systems
Authors:	鍾昕圃;Hsin-Pu Chung
Contributors:	資訊工程研究所
Keywords:	即時性;寬頻分碼多重存取;排程;Real-time;Schedule;WCDMA
Date:	2004-08-30
Issue Date:	2009-09-22 11:36:31 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	在第三代行動通訊中，各種傳輸對服務品質的要求都不相同。為了滿足這些不同的需求，WCDMA是無線端一種重要的存取技術。由於WCDMA系統的容量受限於系統中遭受干擾的總量，所以為了提升系統的使用效能，一個有效的資源分配機制便是一個很重要的議題。我們相信在未來的網路環境，行動端也可能是提供服務的來源，這將使得上行方向的流量大大地增加，因此我們將致力改善於上行方向的傳輸效能。在過去的研究中，單一存取的傳輸模式已經有廣泛的探討。比起傳統CDMA的多重存取，由於這種單一存取的排程式傳輸能有效減少其他使用者產生的干擾，因此可以得到更好的系統效能。不過在這種單一存取的傳輸模式底下，因為使用者在進行傳輸之前必須等待其他比它更早被安排的使用者先完成他們的傳輸，這段等待的時間所造成的延遲隨著使用者越多可能會變得很長而無法滿足對資料有即時性要求的使用者之需求。這個問題的發生是受限於實際系統中的限制，由於單一使用者可能無法充分地使用所有頻寬，造成整個系統的容量及效能並沒有被最佳化。在本篇論文中，我們提出了一個新穎的以傳輸資料大小為基礎的排程式傳輸TASS，它不僅能更有效且還能更充分地利用有限的頻寬。這種傳輸方式跟以往的單一存取以及多重存取模式並不相同，它可以看成是這兩種模式的混合版，我們把它稱為混合式存取。透過TASS的傳輸機制，在完成相同的傳輸量情況底下只需要耗費比較少的能量，我們相信這能有效提升CDMA系統的效能。為了進一步保證每位使用者對延遲時間的要求，我們採用了最早期優先(EDF)的排程方法，這樣使得即使是有即時性要求的傳輸也適用TASS的傳輸方式。實驗結果證明這種新的傳輸模式可以有效增加系統的容量，可以縮短平均延遲時間，同時也可以達到較高的傳輸量。 Wideband code-division multiple-access (WCDMA) is selected as the radio interface technology in the coming 3G wireless network to meet different QoS requirements of heterogeneous traffics. Since the capacity in WCDMA system is limited by interference, an efficient radio resource mechanism is important to enhance overall performance. In the future network, we believe that the server may move to the mobile client resulting that the data volume in uplink will increase considerably, and we concentrate on improving the performance of transmission in uplink. Previous researches have shown that uni-access mode is an efficient way to reduce intracell interference caused by other transmitting users, and hence higher performance is attained compare to traditional multi-access mode. However, the challenge of such scheduled transmission is that higher delay may occur in waiting for service, and this may violate the delay requirements of real-time traffics. The delay problem produced in uni-access mode is due to the constraint in the practical system that a single user might not fully utilize the available bandwidth. Consequently, the system capacity as well as throughput will be not optimized. This thesis introduces a novel Transport block size based Adaptive Scheduling Scheme (TASS) that utilizes radio resource more efficiently and sufficiently. Different from both uni-access and multi-access mode, the TASS can be seen as a mix version of them called hybrid-access mode. Via the transmission strategy, less power is required while achieving equivalent throughput and thus higher performance is expected. In order to guarantee the delay time of each user, the scheduling algorithm earliest deadline first (EDF) is applied. As a result, the TASS is suitable for real-time traffics. The experiment results demonstrate that this new transmission strategy carries advantages in system capacity, average delay and overall throughput.
Appears in Collections:	[Graduate Institute of Computer Science and Information Engineering] Electronic Thesis & Dissertation

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