WIMAX 自動重複請求區塊及傳輸視窗大小考量的下鏈路等比例公平資源分配

Abstract

因為現在網路的迅速成長，網路資源的需求量也相對提升許多，但由於頻寬資源有限，因此要如何分配資源給使用者尚有許多努力的空間；在現有常用的等比例公平資源分配，是一個可以在系統效能與使用者公平性中取得一個較好的平衡的機制。而在IEEE 802.16e標準中 也制定了自動重複請求(automatic repeat request；ARQ)機制，若連線使用了此機制，在媒體存取控制(media access control；MAC)層偵測到收到資料有錯誤時，可用來對針對錯誤資料進行重傳的要求，為了達到自動重複請求機制的目的，資料在傳輸時會根據ARQ區塊及傳輸視窗的大小封裝資料，此封裝方式會影響資源分配使用的效益，造成資源分配顆粒大小的問題，因此在本篇論文中我們將會探討若系統考量ARQ區塊及傳輸視窗的大小兩參數，應該如何執行等比例公平資源分配，我們也提出了三種不同的演算法，將無ARQ機制考量模型的等比例公平資源分配做必較，評估表現效能，實驗結果顯示，在不同的情況下三種結果表現略有些優劣，其中所提出的第三種機制表現較為穩定。

Because of the rapidly growing demand of high quality service over wireless networks, broadband wireless access becomes so important. Since the bandwidth is very precious, the resource should be allocated properly to satisfy the users' demand and keep it fair at the same time. The existing algorithm for proportional fairness is a resource allocation scheme to find a balance between system efficiency and fairness among users. In IEEE 802.16e, the automatic repeat request (ARQ) scheme is used to retransmit data received with error in the media access control (MAC) layer. The granularity of the resource becomes a problem if the connections in the system are all ARQ enabled. In this thesis, we study the problem of resource allocation considering ARQ block size and transmission window size. We propose three different algorithms to address the problem and compare their performances with that of non-ARQ based proportional fair scheme. Simulation results show that the three proposed schemes perform differently for different cases and, in most cases their performances are close to that of the non-ARQ based scheme. The third scheme is more robust.