運用適應性功率範圍與訊號干擾控制於Wi-Fi網路中的最佳化自我修復演算法

Abstract

Wi-Fi無線通訊已經成為一項在公共區域的基本服務。然而，由於以下幾個原因，造成服務品質不良：其一，可用非干擾的頻道數有限；其二，因隨意佈署存取點的情形將造成更大的干擾；其三，使用者的變動分佈，造成服務區域內傳輸情形不均勻。再者，若存取點發生故障時，造成服務中斷，目前尚未有一套完善自我修復的機制。故本文的研究問題是如何在網路存取點發生故障時，藉由自我修復的機制進行修復，同時考量干擾抑制以提供可靠且穩定的服務。目標是最大化最小的可容忍延遲與實際延遲差異以滿足使用者的需求。但是為求達到其他使用者的公平性，本文提出了一個帶有可變動調整傳輸功率的演算法，藉由調整功率的大小，達成小區呼吸(cell breathing)的概念用以當存取點故障時可自我修復。達成兼具自我修復及使用者公平性的目的。

Wi-Fi wireless communication has become a basic service in public areas. But the quality would not be good due to the influential factors: 1) limited numbers of non-overlapping channels, 2) un-planned deployment will cause interference, and 3) the distribution of customers is changed rapidly. It results the traffic distribution is not uniformed. Moreover, the services may not be available due to the failure of APs(Access Points). There is not a well-defined healing mechanism for solving this problem. In this paper, the problems of AP failure and interference are concerned. We propose a Self-Healing algorithm to provide seamless and reliable service based on scenarios of AP failure. The aim of this work is to maximize the minimum gap between actual delay and tolerable delay, and to satisfy each user's demands simultaneously. Variable transmission power range is adjusted to achieve the optimal solution. Cell breathing is also adopted to solve the problem of AP is out of service. So that user fairness of resource allocation and user's Quality of Service(QoS) can be satisfied.