在行動電話之個人通訊服務 (Personal Communication Service, PCS) 網路中,由位置更新 (Location Update) 和傳呼 (Paging) 所構成之位置管理 (Location Management) 機制,使人們無論在何時何地都能夠相互溝通。然而隨著電話用戶 (Subscriber) 人數不斷增加,如何在有限頻寬內做有效地管理並且降低其成本將是十分重要且具討戰性的議題。在本論文中,我們提出一個增強型應用移動速率 (Enhanced Velocity-Based) 之位置更新方法,其利用兩個速率相關參數,速率增加時之時間比例和速率減少時之距離比例,並且採取嚴格增加速率與不輕易減少速率的策略來減少可能發生的振盪 (Oscillation) 現象,減少其成本;另外,許多論文在傳呼策略上,都採取環狀 (Ring) 式細胞搜尋,然而這種方式相當浪費頻寬資源,所以我們設計了一個三步驟之角度式傳呼 (Angular Paging) 策略並配合根據速率快慢調整角度的作法以減少其成本。經由建置一個六邊形蜂巢式 (Cellular) 網路移動環境架構的模擬程式,並與應用移動距離 (Distance-Based) 和應用移動速率 (Velocity-Based)的位置管理機制在各種移動模式 (Mobility Pattern) 下作比較,最後模擬數據顯示我們所提出位置管理機制無論在高速率或者低速率的移動情形下其成本效能都為最佳的。

In personal communication service (PCS) networks, location management composed of location update and paging is used to keep track of mobile terminals (MTs) to enable people with MTs to communicate with each other at any time and any place. However, how to efficiently manage locations and reduce related costs under the limited bandwidth is a fundamental and challenging issue as the number of subscribers increasingly grows. In this thesis, we propose an enhanced velocity-based location update scheme with two velocity-related parameters, i.e., time ratio when velocity goes up and distance ratio when velocity goes down. Adopting the strategy of strictly increasing velocity and not easily decreasing velocity, it can avoid oscillations caused by the original velocity-based location update scheme. Additionally, ring-structured paging has been extensively used in many various location management studies in the literature but it wastes much processing resources. Hence, we design a three-step angular paging strategy which adapts the paging angle according to the velocity to reduce the paging cost. Compared with the distance-based and velocity-based location management schemes, it turns out that our proposed location management schemes perform better for both higher and lower velocities through extensive simulations of the cellular network.

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