一個IEEE 802.16 基地台上考慮延遲與調變之排程機制

Abstract

一個IEEE 802.16基地台上考慮延遲與調變之排程機制 學生：張原誌 指導教授：陳耀宗 博士 國立交通大學網路工程研究所

摘 要

雖然行動WiMAX系統提供了高速的資料傳輸速率以及較廣的頻寬。然而，在一般空氣介質中仍有許多干擾因素存在，因此由於這些干擾使得資料傳輸通道品質在長距離的傳輸上較為不穩定。在WiMAX系統上，若發現傳輸通道品質發生變化，則WiMAX無線網路節點可以改變使用的調變與編碼機制。因此，我們考慮調變與編碼的機制提出了在WiMAX基地台上的排程解決方案。此排程解決方案主要包含三大機制：許可控管機制，排程演算法，頻寬分配機制。除了考慮調變與編碼機制之外，我們針對即時的應用服務也將延遲納入排程考量。 在我們所提出的許可控管機制中，根據節點所使用之根據調變與編碼的機制以及最低保留速率要求計算出進入許可之條件。我們提出精準的許可控管機制不僅可以提昇整個系統的資料吞吐量，亦可以幫助排程器得以保證所有被允許進入連線的最低保留速率。我們考慮調變與編碼機制所提出的排成演算法以及頻寬分配機制，藉由將服務品質的要求轉換為所需的時間來達到保證所有被允許進入連線之最低服務品質需求，而且更能在有限的訊框時間中有效率地分配頻寬。最後列舉出幾項整個排程解決方案的特性： 考慮調變與延遲，在基地台上易於實做， 保證 UGS,rtPS,nrtPS 這些服務之最低服務品質，有效率地分配頻寬。最後，模擬結果顯示出我們所提出之排程機制不僅可以提昇整體網路資料吞吐量而且保證了所有被允許進入網路連結之最低服務品質要求。

A Latency and Modulation Aware Scheduling Solution for IEEE 802.16 Base Stations Student：Yuan-Chih Chang Advisor：Dr. Yaw-Chung Chen Institute of Network Engineering National Chiao Tung University

Abstract The mobile WiMAX system provides high data rate, wide bandwidth for wireless network. However, there are too many interference in the air interface. So, the link quality is not stable owing to air interference and long transmission. When link quality change, mobile node can revise the modulation and coding scheme dynamically. Thus, we propose the modulation-aware scheduling solution for WiMAX Base station. It contains three primary schemes: admission control scheme, scheduling algorithm, and bandwidth allocation scheme. In addition to modulation and coding scheme, we also take latency for real-time service into account. The proposed admission control scheme calculate the admit condition based on the different kinds of modulation and coding schemes and the minimum reserved rate requirements. Our precise admission control scheme can improve the total throughput of entire network and help the scheduler guarantee the minimum reserved rate to each admitted connection. The modulation aware scheduling algorithm and bandwidth allocation scheme can allocate bandwidth more efficiently in the finite frame duration and guarantee the minimum QoS requirements to each admitted connection by translating the QoS requirements into time slots. Some properties of proposed scheduling solution are as follows: modulation and latency aware, easily implemented in BS, guarantee minimum QoS for some specific services (UGS, rtPS, nrtPS), and allocate bandwidth efficiently. Finally, our simulation results show that the proposed scheduling solution can improve the throughput of the entire network and guarantee the minimum QoS requirements to each admitted connection.

Keyword: 802.16, WiMAX, QoS, scheduling, modulation aware.