無線ATM網路上之智慧型複合存取控制

Abstract

在無線ATM網路中，複合存取控制 (Multiple Access Control) 的設計及動態頻寬安排 (Dynamic Bandwidth Allocation) 是兩項最具挑戰性的難題。本論文提出一個多功能的複合存取控制方法，名為智慧型複合存取控制系統 (IMACS)，它可以保證四種傳輸形態 (CBR, VBR, ABR 及需求訊息) 的傳輸品質要求，同時達到最佳網路使用效率。智慧型複合存取控制系統由以下三個部分所組成：複合存取控制器 (MACER)、網路流量監測╱預測器 (TEP) 及智慧型頻寬分配器 (IBA)。複合存取控制器採用混合模式 TDMA，及本文中新提出擁有最佳分割深度的動態分割碰撞處理演算法，網路流量監測╱預測器提供 ABR 流量的線上監測及預測的資料，智慧型頻寬分配器則負責為動態分割碰撞處理演算法取得最佳的分割深度。最後，由數學分析及程式模擬的結果，證明本系統不論網路流量高低都能提供最佳的系統效率。

Two major challenges pertaining to wireless Asynchronous Transfer Mode (ATM) networks are the design of Multiple Access Control (MAC), and dynamic bandwidth allocation. While the former draws much attention, the latter has been considered non-trivial and left mostly unresolved. In this paper, we propose a versatile MAC scheme in conjunction with dynamic bandwidth allocation, referred to as the Intelligent Multiple Access Control System (IMACS), for wireless ATM networks. Supporting four types of services (CBR, VBR, ABR, and signaling requests), IMACS aims to efficiently satisfy their diverse Quality-of-Service (QoS) requirements while retaining a maximum of network throughput. IMACS is composed of three components: Multiple Access Controller (MACER), Traffic Estimator/Predictor (TEP), and Intelligent Bandwidth Allocater (IBA). MACER employs a hybrid-mode TDMA scheme, adopting a new dynamic-tree-splitting Collision-Resolution (CR) algorithm in accordance with the optimal Splitting Depth (SD). TEP performs periodic estimation and on-line predication of three characteristics of ABR traffic assumed self-similar in nature. In cooperation with TEP, IBA dynamically determines the optimal SD of the CR algorithm, and allocates appropriate bandwidth for four supported services. Finally, simulation and analytic results reveal that, with versatile bandwidth control, IMACS offers various QoS guarantees and maximizes network throughput irrespective of traffic variation.