異質無線網路環境下以模擬退火演算法為基礎之群換手決策機制

Abstract

因為各種不同無線網路技術的發展，創造了異質無線網路的環境。為了提供群體(group)存在於大眾交通工具上的行動終端裝置(mobile terminal)無縫的(seamless)網路接取，賦予行動終端裝置多模(multi-mode)的能力讓行動終端裝置能夠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，這些行動終端裝置根據通道狀況回報訊息給基地台進行換手(handover)決定適宜的網路的同時，能夠考慮到使用者的需求以及系統業者的支出便是異質無線網路下群換手決策的重要議題。 在由GSM/EDGE、WCDMA、LTE組成的異質無線網路中，為了降低群體通話阻斷比率、減少換手的頻率、平衡網路之間的交通負載，並且希望保證使用者的服務品質需求(QoS requirement)，在本篇論文中，我們提出了一個以模擬退火(simulated annealing)演算法為基礎並且使用成本函數(cost function)模型來決定群體行動裝置適當網路的群換手決策機制。在模擬結果中顯示我們提出的方法可以有效的降低群體通話阻斷比率，同時能平衡網路之間的負載，除此之外，在群體數量中等時，換手的頻率也有一定幅度的下降，並且能符合品質需求。

Nowadays, a variety of wireless network technologies is developed. Different wireless networks (e.g. GSM/EDGE, WCDMA, LTE) create a heterogeneous wireless network environment. For those multi-mode mobile terminals(MTs), it is important to provide a seamless service for them. When there is a group of MTs stay closely in a vehicle and decide to handover to another networks, it is an important issue to help these MTs to decide a proper target network which is good for both users and the system provider. In this thesis, we tend to reduce the group handover blocking ratio, reduce the number of handover, balance the traffic load between networks, and meet the quality of service (QoS) requirements. Therefore, a simulated annealing based group handover decision scheme using cost function is proposed. In the simulation result, the proposed scheme can reduce the group handover blocking ratio efficiently and balance the load. Besides, when the number of group MTs is not quite large, the number of handover also reductive. Also, it can meet the QoS requirements.