IEEE 802.16是一種無線寬頻網路標準，其具有較高的傳輸速率、較長的通訊距離，以及能支援語音、影像多媒體服務等特點。為了保障各種多媒體應用的服務品質(Quality of Service, QoS)，服務流總共被分成五個類別。這五種服務流可以更進一步的分為即時性服務流及非即時性服務流，若即時性封包的等待時間超過了該封包的最大延遲時間，則該封包就會被丟棄。本論文中，我們提出了一種公平的封包遺失率排程法，使即時性服務流的封包遺失率改善。
首先，在排程的一開始，先檢查即時性服務佇列中每一個封包的時限(deadline)，若過期則丟棄封包，但若在下一個訊框會超過時限的封包我們將他定為緊急封包(emergency packet)。因為封包的遺失率(Loss Rate)會大幅影響服務品質(QoS)，故為了讓即時性服務流佇列中可傳送的緊急封包數能更加公平，我們將根據前一個訊框之即時輪詢服務(rtPS)的封包遺失率，來動態調整目前訊框的延伸之即時輪詢服務(ertPS)及即時輪詢服務(rtPS)佇列中可傳送的最大緊急封包數。
最後，使用加權公平排程演算法(Weighted Fair Queue, WFQ)決定每回合所有服務流佇列中可分配的位元組數，直到所有的可用剩餘頻寬被分配完畢，或是所有佇列中的封包都被排程為止。此排程法不僅能有效控制即時性服務封包的遺失率，對於延伸之即時輪詢服務(ertPS)及即時輪詢服務(rtPS)的封包，也能達到公平地分配及傳輸。

IEEE 802.16 is a standard for wireless communication network. It has the advantages of high transmission rate, long transmission distance and supporting various kinds of multimedia services such as voice and video. To ensure the Quality of Service (QoS) of different application, the service flows are classified into five classes. The five classes of service flows can be summarized as real-time and non-real time. If the waiting time is over the maximum latency of a real-time packet, it will be discarded. In this paper, we will propose a fair loss-rate scheduling algorithm for WiMAX network, to improve the loss-rater of real-time packet.
First, in the beginning of the scheduling, the deadline of each real-time packet will be checked. If the deadline time is over the system time, the packet will be discarded. If the deadline time will be over before next frame starts, the packet will be considered as emergency packet. The emergency packet will lose if it is not scheduled in this frame. Since loss-rate is a significant QoS parameter, the emergency packets of different classes should be scheduled fairly. The allocation of emergency packets for ertPS class should be adjusted according to the loss-rate of rtPS service flows. Otherwise, the loss-rate of rtPS class will not be accepted since it has lower priority.
At the final round, we will use Weighted Fair Queue algorithm to allocate the packets of all service flows until all available bandwidth is allocated or all packets are scheduled. With this algorithm, the loss rate is well controlled for all real-time service flows.

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