異質無線網路環境下以議價式賽局為基礎之網路選取機制

Abstract

因為各種不同無線網路接取技術的發展，創造了異質網路的環境。為了提供行動用戶無縫式(seamless)的網路接取，讓行動用戶能夠連接到多元異質網路的能力在此環境下是不可或缺的。賦予行動用戶多模(multi-mode)的能力，並且能使他們根據通道狀況或自身的服務品質需求(QoS requirement)選擇更適宜的網路的同時，也能夠考慮到系統業者便是異質網路選擇重要的議題。為了支援高傳輸速率的多媒體服務以及高速的行動用戶，一個CDMA/WMAN/WLAN的異質網路被提出。 在CDMA/WMAN/WLAN的異質網路系統中，為了增加系統吞吐量、減少換手(handoff)的頻率，並且同時保證使用者的服務品質需求，在本篇論文中我們提出了一個以議價式賽局為基礎的網路選取機制。在所定義的議價式賽局中，使用者對網路的喜好程度函式是用來得到行動用戶對服務品質需求的滿足程度，而網路對使用者的喜好程度函式則是用來達到負載平衡(loading balance)及減少換手頻率。藉由行動用戶與網路議價所得到的結果，我們最後會決定一個最合適的接取網路。模擬中顯示我們提出的方法可以減少新使用者被拒絕進入系統中的機率，同時能降低已存在的使用者被強迫中止(forced terminated)的機率。除此之外，換手的頻率也大幅度的下降，並且能符合服務品質需求。

Because of the variety of wireless network technologies, different networks (e.g. CDMA, WLAN, OFDMA-based MAN) create a heterogeneous wireless environments and the network selection problem in such a heterogeneous wireless environments becomes an important issue. In this situation, the mobile terminals with multi-mode have the capability to connect to different types of networks. For the reasons of the fully resource utilization and providing the seamless communications, selecting the most appropriate radio access network will be the main objective. In this thesis, a network selection method that using bargaining game is proposed. We consider the aspect of the user and the network by using predefined utility functions that one can measure the satisfaction of QoS requirements of the call request and the other can measure the suitability that call request is accepted by the network from the perspective of the network. Considering the perspective of the user and the network are different, we use bargaining game to make the decision to maximize system throughput and decreasing the number of handoffs.