由於無線通訊及非同步傳輸模式(asynchronous transfer mode; ATM)技術的快速發展，無線ATM網路已經在世界各地扮演非常重要角色。本篇論文著重的特色是在討論以多重載送分碼多工(multi-carrier code division multiple access；MC-CDMA)技術為基底的無線ATM網路。MC-CDMA可在同一時間內使用多個虛擬雜訊碼(pseudorandom noise code; PN codes）傳送資料，使得網路整體輸出率有效提高並且能同時支援不同交通流量。移交管理在無線ATM行動通信系統中是重要的課題。對於軟式移交關係著兩個以上的基地台引導信號的強度的改變，他們有條件去決定是否需要移交。這篇論文主要針對軟式移交管理的研究去解決兩個深具意義的問題來降低移交斷訊率(handoff call dropping probability)，一是熱點細胞(hot-spot cell)，一是資源管理(resource management)。某個基地台服務範圍內突然湧入許多使用者，將會造成此基地台流量過載，形成所謂的熱點細胞，而鄰近基地台可能處於輕載狀態，造成系統流量負載不平衡現象。由於頻寬資源是有限且共享的，因此為了使有限的頻寬資源更有效地使用，我們利用行動台越區移交的機制來減緩流量負載不平衡的現象。我們提出一個完整性流量轉載軟式越區移交機制（complete traffic shedding algorithm for soft handoff；CTSA），藉由調整移交門檻參數來有效地降低基地台服務範圍內的負載。實際上我們是減少過載基地台的移交區域範圍，並不是調整基地台的傳輸功率。位於過載基地台邊緣附近的使用者能夠提早移交到鄰近輕負載的基地台，並延後鄰近基地台的使用者進入過載基地台，來達到減輕負載的效果。另外，在資源管理方面，我們提出一個動態資源管理機制(dynamic resource allocation scheme; DRAS)來改善效能。最後，分析我們的演算法並透過模擬方式與其他已提出的方法互相比較。CTSA和DRAS確實比其他方法有更好的效能。

Worldwide, the role of wireless ATM (Asynchronous Transfer Mode) network has already become very important because of the progress of ATM technique and wireless communications. This thesis focuses on the characteristics of the wireless ATM networks based on multi-carrier code division multiple access (MC-CDMA) technique. MC-CDMA technique can use several pseudorandom noise codes (PN codes) to transmit in the same period to obtain higher throughput and support different traffic streams. Handoff management is an important issue in wireless ATM mobile communication systems. With soft handoff, a conditional decision is made on when to hand off, which depends on the changes in pilot signal strength from the two or more base stations involved. The main aimed of this thesis is to study on soft handoff management, which resolves two significant problems, hot-spot cell and resource management, to decrease handoff call dropping probability. An abrupt increase of mobile users in a specific base station (BS) will make traffic overloaded and become a so-called hot-spot cell, which causes an unbalanced traffic load condition because the traffic load in the neighboring BSs may be light. In order efficiently to utilize a limited bandwidth, it is necessary to use a good mobile handoff strategy to alleviate unbalanced traffic load condition. This thesis proposes a complete traffic shedding algorithm (CTSA) for soft handoff efficiently to alleviate the overloaded traffic in a hot-spot cell by adjusting handoff parameters, which virtually reduces the service coverage of the heavy loaded BS without adjusting the transmission power. The mobile users located in the outer area of the hot-spot cell will early handoff to the neighboring BSs with light traffic load; and the mobile users in the neighboring BSs postpone to handoff to the hot-spot cell, so that the traffic load of the hot-spot cell can be decreased. In addition, in resource management, we propose a dynamic resource allocation scheme (DRAS) to improve performance. After analyzing the proposed algorithm and comparing the other methods by simulation, the performance of CTSA and DRAS algorithms are better than the others.

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