無線ATM 網路使用續存性位置管理機制之研究

Study on Survivable Location Management Scheme in Wireless ATM Networks

近年個人行動通訊服務（personal communication service; PCS）蓬勃發展，其中無線通訊中的移動性（mobility）是主要討論的課題，提供使用者可以隨意移動的能力，在行動通訊系統中，尤其位置管理是相當重要的技術之一。位置管理主要目標在處理無線網路下如何有效率地找到無線使用者。本文提出的續存性分散式位置管理（survivable distribution location management; SDLM）機制，是針對固定式無線非同步傳輸模式（wireless asynchronous transfer mode; WATM）網路用分群式（grouping）的方法做階層化（hierarchy）進行改良。除了現行的集中式管理方式外，我們以分散式的概念將網路拓樸在邏輯上重新定義，用分散式來取代集中式的管理，並且納入備援的考量。經模擬證明在一般的網路拓樸下，SDLM 可有效解決集中式HLR（home location register; HLR）負荷太重、傳遞訊息次數過多、以及階層式連線時間過長等缺點。因此，SDLM 可以有效降低位置管理的成本且與現實使用備援的情況相呼應。

In recent years, personal communication service (PCS) technology hasrapidly advanced such that random motion in wireless communications isone of the most discussable issues in the field now. Location managementtherefore has become one of the most important topics to study to enhancethe ability to locate wireless users efficiently. This paper proposes asurvivable distribution location management (SDLM) scheme thatimproves the grouping and hierarchy of the mobile ATM switch in thewireless asynchronous transfer mode (WATM). Different from thetraditional centralised management approach, this paper usesdecentralization and backup concepts instead and attempts to redefine thenetwork topology for decentralized location management. Simulation results allowed us to compare and contrast our results with currentcentralized location management system results, resulting in evidence toindicate that our proposed method more efficiently lowers the cost oflocation management and more readily responds to actual backup systems.