- 學位論文
WiMAX系統中上下行頻寬動態配置及封包排程之研究
A Research of Dynamic uplink and downlink bandwidth allocation and packet scheduling mechanism in WiMAX System
摘要
目前人們已經可以說是無法離開網路而生活，為了要讓人們可以無時無刻都可以取存網路，IEEE就提出了IEEE 802.11系統的無線網路技術，希望可以使網路的存取更為便利，但是現在人們需要無線網路所來提供的服務不再侷限在單純的文字或圖片的傳輸，取而代之的是大量的影音多媒體資料，並且IEEE 802.11系統的技術除了頻寬不足以滿足大量的影音多媒體服務之外，依然無法使得地處偏遠或是在網路不易佈建的地方能以較經濟及便利的方式來存取無線網路，所以IEEE又提出了IEEE 802.16系統的無線寬頻網路技術─也就是WiMAX。 本論文的主旨是在探討如何在WiMAX的架構下，要如何利用有限的頻寬來滿足多媒體資料的傳輸需求，並且又不會過份的排擠到優先權較低的其他服務(如FTP、HTTP等)。我們提出了一個可以應用在WiMAX上的上下行頻寬分配及封包排程機制，利用各種服務對服務品質需求的不同特性來做不同的頻寬配置及封包排程，希望可以藉由這個機制使的網路上各種不同的服務都可以獲得所需要的資源，並且可以使得珍貴的頻寬可以做最大效率的使用。
並列摘要
Nowadays, the convenient of the network has changed the human’s life. To make people access the network easier, IEEE developed IEEE 802.11, so called Wi-Fi, wireless network technology. But with the limit of Wi-Fi to bandwidth, transmission range and mobility speed, people can’t really access internet at any where, any time. To satisfy the need of human, IEEE develops a new wireless technology, the IEEE 802.16, so called WiMAX, to provide an access of wideband, large transmission range and high mobility speed. WiMAX classifies network services into four classes according to the different requirement of the quality-of-service (QoS) to the network. In order to meet various QoS requirements, we proposed a bandwidth allocation mechanism in conjunction with packet scheduling to efficiently allocate the bandwidth to both uplink and downlink traffic simultaneously. The mechanism is based on the priority and available time that packets must be sent out. The main objective is to lower the packet drop rate of real-time high priority traffic, such as Unsolicited Grant Services (UGS) and Real Time Protocol Services (rtPS) while keeps the high utilization of radio resource of a base station. In addition, the average packet delay under various loading conditions and the fairness of bandwidth allocation among subscriber stations will also be examined.