WIMAX環境下即時影像傳輸服務之效能評估

近年來隨著無線網路與多媒體的日漸普遍，其中以即時影像傳輸應用更是快速發展，而即時影像傳輸應用對於無線網路的QoS (Quality of Service)有一定的要求，因此如何在有限的網路頻寬,有效的利用資源來提供服務品質獲得良好的網路效能便顯得十分重要。IEEE 802.16團隊所制定的IEEE 802.16都會型無線網路技術(WiMAX)，擁有傳輸距離長、傳輸速率高、提供QoS保證的優點，因此適合用來做為傳輸即時影像等多媒體應用，並且可透過其服務品質QoS如網路排程以及佇列的頻寬分配來提供各種各樣的網路即時應用程式更有效率。　　本篇論文主要探討在WIMAX環境下即時影像應用的效能分析，在影像傳輸方面我們使用MPEG-4壓縮格式，其擁有高壓縮率且具有相當的影像品質適合應用於無線資料傳輸。在網路模擬軟體方面選擇學術界廣泛使用的網路模擬軟體Network Simulation 2(NS2)來建構一個WiMAX網路環境，透過使用不同排程管理機制及調整循環字首(Cyclic Prefix; CP)來模擬隨著節點數增加時即時影像傳輸的效能變化如網路容量，平均延遲時間，吞吐量，封包遺失率，平均抖動率及影像品質評鑑指標PSNR。最後我們將影像跟VoIP建立在同一節點上來模擬影像電話應用並使用不同服務模式來分析其效能。結論我們得到在容許延遲150毫秒下主動式演算法RED相較於其他3種演算法其網路容量為最高，循環字首CP為1/32時其網路容量為15使用者是CP1/4的1.5倍，以及rtPS服務相較於UGS服務較適合用於影像跟VoIP建立的影像電話應用。

關鍵字

Video ； IEEE 802.16 ； WiMAX ； QoS

並列摘要

In recent years, multimedia over wireless network develop rapid, especially in real-time video transmission application that need certain requirements for the wireless network QoS. Therefore, how to effectively use resources to provide quality of service and improve network performance is very important. The IEEE formed a group called 802.16 to develop a standard for what was called a wireless metropolitan area network; WIMAX, which has long transmission distance, high transfer rate, QoS guarantees. And through network scheduling and queue bandwidth allocation to provides a variety of internet real-time applications more efficient. This thesis focuses in WIMAX environment analysis performance of real-time video application. About video transmission, we use the MPEG-4 compression format, which with high compression ratio and excellent image quality suitable for wireless data transmission. The network simulation software we chose the current popular Network Simulation 2 (NS2) to build our WIMAX network environment. Through different scheduling mechanism and Cyclic Prefix (CP) to simulate variation of performance for real-time video transmission with number of nodes increases such as network capacity, average delay, throughput, packet loss, average jitter, and PSNR. Finally we compare performance of different type service for combine video traffic and VoIP traffic with single node to simulate video telephone application. The result we get Active Queue Management RED has highest network capacity than other compare Queue Management under latency guideline 150ms and which network capacity of CP1/32 for 15nodes, which is 1.5times than CP1/4, and the rtPS service more suitable than UGS service for video telephone application that combines video traffic and VoIP traffic.

並列關鍵字

Video ； IEEE 802.16 ； WiMAX ； QoS

參考文獻

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國際替代計量

WIMAX環境下即時影像傳輸服務之效能評估

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