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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/8576


    Title: 針對WCDMA下傳方向並以服務品質為基礎的混合型多重存取傳輸機制;A QoS-based Hybrid Multiple Access Transmission Strategy in WCDMA Downlink
    Authors: 張浩偉;Hao-Wei Chang
    Contributors: 資訊工程研究所
    Keywords: 下傳方向;寬頻多重分碼存取;混合型多重存取;服務品質;QoS;HMA;Downlink;WCDMA
    Date: 2002-06-19
    Issue Date: 2009-09-22 11:30:52 (UTC+8)
    Publisher: 國立中央大學圖書館
    Abstract: 目前第三代行動電話系統中,WCDMA是提供無線端高速存取技術的一個首要候選者。現行的第二代行動電話系統包括了最普遍的GSM以及GPRS已經能夠提供可接受的語音服務和低速的資料服務。然而第三代行動電話系統的理想是針對多重的服務包括及時性與非及時性傳輸提供更高的服務品質。隨著Internet的成長,影音串流服務與網頁瀏覽更受歡迎,但是這些資料屬於非對稱性傳輸,因此對於下載的要求是多於上傳的。由此可見,下載方向的傳輸會是瓶頸所在,而我們將努力提升下載的服務品質。 在這篇論文中,我們致力於降低及時性傳輸的平均封包延遲和非及時性傳輸的位元錯誤率。此外,我們也試圖提升系統的服務等級並增加系統流量。這篇論文針對下列四個議題進行建議與評估: (1)無線訊號存取 (2)允入控制 (3)電源配置 (4)排程管理。我們提出一個新的混合型多重存取傳輸機制,整合了傳統的多重存取模式與新穎的單一存取模式以降低平均封包延遲、位元錯誤率並增加系統流量。這個機制提供了選擇多重存取模式或單一存取模式的方法,其原則是根據何者能提供較高的服務品質。依照基地台運作時所偵測到的服務品質結果,我們設計了一個允入控制策略來處理及時性與非及時性傳輸的要求,包括了新的傳輸或是已存在而要換基地台的傳輸。由於WCDMA系統的容量是限制於干擾的總量,因此一個滿足服務品質而不過量的電源配置方法被推導出來。我們也提出了一個新的排程方法,對及時性傳輸採用了最早期限優先(EDF),而對非及時性傳輸則採用了靜態優先排程(SPS),以分別符合封包延遲與位元錯誤率的要求。 為了更進一步依照分析結論來決定何時採用多重存取模式或單一存取模式,我們為先前的混合型多重存取傳輸機制提出了一個系統流量最佳化的延伸。我們的目標是系統流量的增加但是服務品質尤其是平均封包延遲的效能亦同時被考慮。 我們只考慮WCDMA系統的無線存取網路部份並對其評估服務的品質。效能分析是建立在一個動態模擬環境,包括多個細胞基地台、四種傳輸應用型態、基地台的切換與跨細胞基地台間的干擾。模擬結果證明了我們提出的混合型多重存取傳輸機制比一般多重存取的CDMA系統提供較佳的服務等級、較低的平均封包延遲、較低的位元錯誤率以及較高的系統流量。 第二章介紹我們提出的系統架構以及各項做法,包括無線訊號存取、允入控制、電源配置與排程管理。此外,我們也提出一個針對系統流量進行最佳化的做法。第三章則介紹實驗模擬環境以及相關的模擬結果。第四章是結論與討論。 WCDMA (Wideband CDMA) is the primary candidate for the radio access technology with high data rate capability for the third generation (3G) cellular systems. Current 2G systems including the most popular GSM and an upgrade extension of GPRS have provided acceptable voice service and low bit rate data service. However, the main goal of the 3G systems is trying to further support multi-service including real-time and non real-time traffics in better quality. As Internet grows up, data services of video streaming and web browsing become more attractive but the data transmissions are asymmetric so that the downlink demands are much higher than the uplink ones. It is clear that the downlink is the bottleneck and we concentrate on improving the quality of service (QoS) of the downlink. In this thesis, we devote to decrease the mean packet delay for real-time traffics and the bit error rate (BER) for non real-time traffics. Additionally, we try to increase the grade of service (GOS) and the throughput. Four issues are carefully proposed and evaluated in this thesis: (1) Radio access. (2) Admission control. (3) Power allocation. (4) Scheduling. A new hybrid multiple access (HMA) transmission strategy that integrates the traditional mutli-access mode and the novel uni-access mode is proposed to decrease the mean packet delay, bit error rate (BER) and increase the throughput. The HMA provides an approach to choose transmission mode from either uni-access or multi-access that guarantees higher QoS provision. After QoS provision measurements of the target base station, we design an admission control policy based on QoS threshold to deal with real-time and non real-time calls from handoff or new arrival. A sufficient but not superabundant power allocation scheme is derived because the capacity of a WCDMA system is interference limited. We also propose a new scheduling algorithm including the earliest deadline first (EDF) for real-time traffics and the static priority scheduling (SPS) for non real-time traffics to meet the delay and BER requirements respectively. In order to further make analytical decisions between uni-access and multi-access transmission mode, a throughput optimization extension for the HMA is proposed. The throughput gain is our objective but the QoS provision especially the mean packet delay is considered at the same time. Only the radio access network is taken into account and the QoS provision is evaluated. The performance analysis is carried on a dynamic simulation environment including multiple cells, four traffic types, hard handoff and inter-cell interference. The results show that the HMA outperforms the general multi-access CDMA system with better GOS, lower mean packet delay, lower BER and higher throughput. Our proposed system architecture as well as algorithms including radio access, admission control, scheduling and power allocation are presented in chapter II. The Simulation model and results are described in chapter III. Chapter IV concludes this thesis.
    Appears in Collections:[資訊工程研究所] 博碩士論文

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