行動通訊網路之移動管理分析

Abstract

隨著行動通訊硬體的進步以及手機使用人口的成長，移動管理的重要性越顯增加。移動管理在行動通訊所扮演的角色主要是去追蹤手機用戶的地點，以達到能夠提供通話、傳/收簡訊、行動上網等等的功能；因此，如何利用成本最低的方式去追蹤手機用戶的位置，這其中包含了location update(LU)及paging的概念，便是我們研究的課題。在這篇論文中，我們採用了UMTS以及GSM的歷史通話資料，從這些資料中，我們可以分析出基地台之間的相關性，進而知道他們彼此是否就在鄰近位置；藉由這些歷史資料分析，我們也能夠進一步去規畫整個行動網路的劃分方法。除此之外，本研究也將Long Term Evolution (LTE)的架構一起做考量，也在不同的paging架構下分析出最佳的TA 及TAL規劃方式。最後我們的結果指出在GSM以及UMTS裡的LA-based simultaneous paging的成本會比LTE中TAL-based paging還要低；但若採用一種sequential paging的方式，先page TA，再page TAL的方式，雖然會使paging的時間成本變大，但卻可以大幅地降低LTE的整體成本；除此之外，我們也發現不管在GSM、UMTS還是LTE，若能採用歷史通話資料，一種基於Handoff(HO) pair的這種鄰近基地台paging方式，都能達到最低的成本。

Mobility management is an important design issue of cellular networks. The aim of mobility management is to track where the users are, allowing calls, SMS and other mobile services to be delivered to them. Our purpose is to find an efficient mobility management strategy to minimize the total cost for both of location update (LU) and paging. In this thesis, we use the anonymized records of both UMTS and GSM so that we can learn user mobility patterns between cells. Based on the knowledge of user mobility patterns, we study the optimum planning of location areas (LAs) where a variety of paging strategies are used. In addition, we study the mobility management of Long Term Evolution (LTE) networks. Using the history signaling data, we investigate the optimum TA and TAL planning under a variety of paging schemes. The overall cost includes the location update cost and the paging cost. Based on the number of control messages exchanged in the cellular network, proper costs for location updates and cell paging were used in our analysis. Our analytic results indicate that using simultaneous paging LA-based paging used in GSM and UMTS outperforms TAL-based paging used in LTE. A sequential paging scheme, which pages TA first, and then TAL, can reduce the overall cost of LTE at the cost of longer paging latency. A sequential paging based on the distances between cells in cell neighbor graph provides the minimum overall cost for all generations of cellular network.